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Sample records for surface-enhanced laser desorption

  1. Peak quantification in surface-enhanced laser desorption/ionization by using mixture models

    NARCIS (Netherlands)

    Dijkstra, Martijn; Roelofsen, Han; Vonk, Roel J.; Jansen, Ritsert C.

    2006-01-01

    Surface-enhanced laser desorption/ionization (SELDI) time of flight (TOF) is a mass spectrometry technology for measuring the composition of a sampled protein mixture. A mass spectrum contains peaks corresponding to proteins in the sample. The peak areas are proportional to the measured

  2. Optimising the Use of TRIzol-extracted Proteins in Surface Enhanced Laser Desorption/ Ionization (SELDI Analysis

    Directory of Open Access Journals (Sweden)

    Perlaky Laszlo

    2006-03-01

    Full Text Available Abstract Background Research with clinical specimens is always hampered by the limited availability of relevant samples, necessitating the use of a single sample for multiple assays. TRIzol is a common reagent for RNA extraction, but DNA and protein fractions can also be used for other studies. However, little is known about using TRIzol-extracted proteins in proteomic research, partly because proteins extracted from TRIzol are very resistant to solubilization. Results To facilitate the use of TRIzol-extracted proteins, we first compared the ability of four different common solubilizing reagents to solubilize the TRIzol-extracted proteins from an osteosarcoma cell line, U2-OS. Then we analyzed the solubilized proteins by Surface Enhanced Laser Desorption/ Ionization technique (SELDI. The results showed that solubilization of TRIzol-extracted proteins with 9.5 M Urea and 2% CHAPS ([3-[(3-cholamidopropyl-dimethylammonio]propanesulfonate] (UREA-CHAPS was significantly better than the standard 1% SDS in terms of solubilization efficiency and the number of detectable ion peaks. Using three different types of SELDI arrays (CM10, H50, and IMAC-Cu, we demonstrated that peak detection with proteins solubilized by UREA-CHAPS was reproducible (r > 0.9. Further SELDI analysis indicated that the number of ion peaks detected in TRIzol-extracted proteins was comparable to a direct extraction method, suggesting many proteins still remain in the TRIzol protein fraction. Conclusion Our results suggest that UREA-CHAPS performed very well in solubilizing TRIzol-extracted proteins for SELDI applications. Protein fractions left over after TRIzol RNA extraction could be a valuable but neglected source for proteomic or biochemical analysis when additional samples are not available.

  3. Preanalytical and analytical variation of surface-enhanced laser desorption-ionization time-of-flight mass spectrometry of human serum

    DEFF Research Database (Denmark)

    Albrethsen, Jakob; Bøgebo, Rikke; Olsen, Jesper

    2006-01-01

    BACKGROUND: Surface-enhanced laser desorption-ionization time-of-flight (SELDI-TOF) mass spectrometry of human serum is a potential diagnostic tool in human diseases. In the present study, the preanalytical and analytical variation of SELDI-TOF mass spectrometry of serum was assessed in healthy...... was 18% (6%-34%, n=4) for 16 peaks, and inter-individual CV was 38% (16%-56%, n=16) for 20 peaks. CONCLUSIONS: The pre-analytical and analytical conditions of SELDI-TOF mass spectrometry of serum have a significant impact on the protein peaks, with the number of peaks low and the assay variation high...

  4. Application of surface-enhanced laser desorption/ionization time-of-flight mass spectrometry coupled with an artificial neural network model for the diagnosis of hepatocellular carcinoma.

    Science.gov (United States)

    Hu, Qiongying; Huang, Yuanshuai; Wang, Zhuan; Tao, Hualin; Liu, Jinbo; Yan, Li; Wang, Kaizheng

    2012-09-01

    There are no satisfactory biomarkers for hepatocellular carcinoma (HCC). The surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) technique has been used to identify biomarkers for cancer. Four hundred thirty five serum samples were tested by SELDI-TOF-MS matching on a gold chip. Samples were assigned to a training set and a testing set according to collection order. The training set was used to identify statistically significant peaks and to develop the artificial neural network (ANN) model for diagnosing HCC. The testing set was used in a blind test to validate the diagnostic efficiency of the ANN model. A total of 75 proteins that differed between patients and controls were identified (pcontrols. The ANN is a new method for diagnosing and identifying HCC.

  5. Identification of protein biomarkers in Dupuytren's contracture using surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS).

    Science.gov (United States)

    O'Gorman, David; Howard, Jeffrey C; Varallo, Vincenzo M; Cadieux, Peter; Bowley, Erin; McLean, Kris; Pak, Brian J; Gan, Bing Siang

    2006-06-01

    To study the protein expression profiles associated with Dupuytren's contracture (DC) to identify potential disease protein biomarkers (PBM) using a proteomic technology--Surface Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS). Normal and disease palmar fascia from DC patients were analyzed using Ciphergen's SELDI-TOF-MS Protein Biological System II (PBSII) ProteinChip reader. Analysis of the resulting SELDI-TOF spectra was carried out using the peak cluster analysis program (BioMarker Wizard, Ciphergen). Common peak clusters were then filtered using a bootstrap algorithm called SAM (Significant Analysis of Microarrays) for increased fidelity in our analysis. Several differentially expressed low molecular weight (mass standard deviation for both methods of biomarker-rich low molecular weight region of the human proteome. Application of such novel technology may help clinicians to focus on specific molecular abnormalities in diseases with no known molecular pathogenesis, and uncover therapeutic and/or diagnostic targets.

  6. Identifying serum biomarkers for ovarian cancer by screening with surface-enhanced laser desorption/ionization mass spectrometry and the artificial neural network.

    Science.gov (United States)

    Yang, Jing; Zhu, Yanhui; Guo, Hongyan; Wang, Xiuyun; Gao, Ronglian; Zhang, Lufang; Zhao, Yangyu; Zhang, Xiaowei

    2013-05-01

    The purpose of this study was to screen potential serum tumor biomarkers for the diagnosis of ovarian cancer. The study includes 3 sets. The first set of patients included 37 ovarian cancers and 31 healthy women (healthy controls). The second set included 42 ovarian cancers, 33 patients with benign ovarian tumor, and 29 healthy women (noncancer controls). The third set included 39 ovarian cancers and 35 patients with benign ovarian tumor (benign controls). Serum samples from ovarian cancers, healthy controls, noncancer controls, and benign controls were analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. A 3-peak model (peaks of mass-to-charge ratio values at 5766.379 d, 5912.586 d, and 11695.56 d) was established in the training set that discriminated cancer from noncancer with high sensitivity (10/11, 90.90%) and specificity (19/20, 95.00%). The peaks corresponding to 3 potential biomarkers increased significantly with the degree of malignancy. The proteins represented by these 3 peaks are biomarker candidates for ovarian cancer diagnosis and/or monitoring treatment response.

  7. Biomarker research for moyamoya disease in cerebrospinal fluid using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Maruwaka, Mikio; Yoshikawa, Kazuhiro; Okamoto, Sho; Araki, Yoshio; Sumitomo, Masaki; Kawamura, Akino; Yokoyama, Kinya; Wakabayashi, Toshihiko

    2015-01-01

    Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by steno-occlusive change in bilateral internal carotid arteries with unknown etiology. To discover biomarker candidates in cerebrospinal fluid from MMD patients, proteome analysis was performed by the surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Three peptides, 4473Da, 4475Da, and 6253Da, were significantly elevated in MMD group. A positive correlation between 4473Da peptide and postoperative angiogenesis was determined. Twenty MMD patients were enrolled in this pilot study, including 11 pediatric cases less than 18 years of age (mean age, 8.67 years) and 9 adult MMD patients (mean age, 38.1 years). This study also includes 17 control cases with the mean age of 27.9 years old. In conclusion, 4473Da peptide is supposed to be a reliable biomarker of MMD. 4473Da peptide showed higher intensity peaks especially in younger MMD patients, and it was proved to be highly related to postoperative angiogenesis. Further study is needed to show how 4473Da peptide is involved with the etiology and the onset of MMD. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  8. A prototype methodology combining surface-enhanced laser desorption/ionization protein chip technology and artificial neural network algorithms to predict the chemoresponsiveness of breast cancer cell lines exposed to Paclitaxel and Doxorubicin under in vitro conditions.

    Science.gov (United States)

    Mian, Shahid; Ball, Graham; Hornbuckle, Jo; Holding, Finn; Carmichael, James; Ellis, Ian; Ali, Selman; Li, Geng; McArdle, Stephanie; Creaser, Colin; Rees, Robert

    2003-09-01

    An ability to predict the likelihood of cellular response towards particular chemotherapeutic agents based upon protein expression patterns could facilitate the identification of biological molecules with previously undefined roles in the process of chemoresistance/chemosensitivity, and if robust enough these patterns might also be exploited towards the development of novel predictive assays. To ascertain whether proteomic based molecular profiling in conjunction with artificial neural network (ANN) algorithms could be applied towards the specific recognition of phenotypic patterns between either control or drug treated and chemosensitive or chemoresistant cellular populations, a combined approach involving MALDI-TOF matrix-assisted laser desorption/ionization-time of flight mass spectrometry, Ciphergen protein chip technology and ANN algorithms have been applied to specifically identify proteomic 'fingerprints' indicative of treatment regimen for chemosensitive (MCF-7, T47D) and chemoresistant (MCF-7/ADR) breast cancer cell lines following exposure to Doxorubicin or Paclitaxel. The results indicate that proteomic patterns can be identified by ANN algorithms to correctly assign 'class' for treatment regimen (e.g. control/drug treated or chemosensitive/chemoresistant) with a high degree of accuracy using boot-strap statistical validation techniques and that biomarker ion patterns indicative of response/non-response phenotypes are associated with MCF-7 and MCF-7/ADR cells exposed to Doxorubicin. We have also examined the predictive capability of this approach towards MCF-7 and T47D cells to ascertain whether prediction could be made based upon treatment regimen irrespective of cell lineage. Models were identified that could correctly assign class (control or Paclitaxel treatment) for 35/38 samples of an independent dataset. A similar level of predictive capability was also found (> 92%; n = 28) when proteomic patterns derived from the drug resistant cell line MCF-7

  9. Laser desorption mass spectrometry for molecular diagnosis

    Science.gov (United States)

    Chen, C. H. Winston; Taranenko, N. I.; Zhu, Y. F.; Allman, S. L.; Tang, K.; Matteson, K. J.; Chang, L. Y.; Chung, C. N.; Martin, Steve; Haff, Lawrence

    1996-04-01

    Laser desorption mass spectrometry has been used for molecular diagnosis of cystic fibrosis. Both 3-base deletion and single-base point mutation have been successfully detected by clinical samples. This new detection method can possibly speed up the diagnosis by one order of magnitude in the future. It may become a new biotechnology technique for population screening of genetic disease.

  10. Deuterium desorption from tungsten using laser heating

    Directory of Open Access Journals (Sweden)

    J.H. Yu

    2017-08-01

    Full Text Available Retention and desorption of hydrogenic species need to be accurately modeled to predict the tritium inventory of next generation fusion devices, which is needed both for tritium fuel recovery and for tritium safety concerns. In this paper, experiments on thermal desorption of deuterium from intrinsic polycrystalline tungsten defects using laser heating are compared to TMAP-7 modeling. The samples during deuterium plasma exposure were at a temperature of 373K for this benchmark study with ion fluence of 0.7–1.0 ×1024Dm−2. Following plasma exposure, a fiber laser (λ= 1100nm heated the samples to peak surface temperatures ranging from ∼500 to 1400K with pulse widths from 10ms to 1s, and 1 to 10 pulses applied to each sample. The remaining deuterium retention was measured using temperature programmed desorption (TPD. Results show that > 95% of deuterium is desorbed when the peak surface temperature reached ∼950K for > 1s. TMAP-7 is used to predict deuterium desorption from tungsten for a range of surface temperatures and heating durations, and is compared to previous work on desorption from beryllium codeposits.

  11. Substrate-Enhanced Micro Laser Desorption Ionization Mass Spectrometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne Research, Inc. and the University of Massachusetts at Amherst will collaborate to develop laser desorption ionization (LDI) mass spectrometric analysis of...

  12. The controlled pulsed laser deposition of Ag nanoparticle arrays for surface enhanced Raman scattering.

    Science.gov (United States)

    D'Andrea, C; Neri, F; Ossi, P M; Santo, N; Trusso, S

    2009-06-17

    An effective method for the production of surface enhanced Raman scattering (SERS) active substrates is presented. Nanostructured silver thin films are pulsed laser deposited in an argon atmosphere. The films consist of arrays of nanoparticles whose size is controlled by the Ar pressure. The surface morphology of the films can be tuned by the laser pulse number. Nanoparticle size is calculated by a phenomenological model taking into account the dynamics of the laser generated silver plasma. The SERS activity of the films is investigated by Raman scattering of adsorbed rhodamine 6G at different concentrations.

  13. Laser desorption mass spectrometry for biomolecule detection and its applications

    Science.gov (United States)

    Winston Chen, C. H.; Sammartano, L. J.; Isola, N. R.; Allman, S. L.

    2001-08-01

    During the past few years, we developed and used laser desorption mass spectrometry for biomolecule detections. Matrix-assisted laser desorption/ionization (MALDI) was successfully used to detect DNA fragments with the size larger than 3000 base pairs. It was also successfully used to sequence DNA with both enzymatic and chemical degradation methods to produce DNA ladders. We also developed MALDI with fragmentation for direct DNA sequencing for short DNA probes. Since laser desorption mass spectrometry for DNA detection has the advantages of fast speed and no need of labeling, it has a great potential for molecular diagnosis for disease and person identification by DNA fingerprinting. We applied laser desorption mass spectrometry to succeed in the diagnosis of cystic fibrosis and several other nerve degenerative diseases such as Huntington's disease. We also succeeded in demonstrating DNA typing for forensic applications.

  14. Laser desorption mass spectrometry for biomolecule detection and its applications

    International Nuclear Information System (INIS)

    Winston Chen, C.H.; Allman, S.L.; Sammartano, L.J.; Isola, N.R.

    2001-01-01

    During the past few years, we developed and used laser desorption mass spectrometry for biomolecule detections. Matrix-assisted laser desorption/ionization (MALDI) was successfully used to detect DNA fragments with the size larger than 3000 base pairs. It was also successfully used to sequence DNA with both enzymatic and chemical degradation methods to produce DNA ladders. We also developed MALDI with fragmentation for direct DNA sequencing for short DNA probes. Since laser desorption mass spectrometry for DNA detection has the advantages of fast speed and no need of labeling, it has a great potential for molecular diagnosis for disease and person identification by DNA fingerprinting. We applied laser desorption mass spectrometry to succeed in the diagnosis of cystic fibrosis and several other nerve degenerative diseases such as Huntington's disease. We also succeeded in demonstrating DNA typing for forensic applications

  15. Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Lina [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Franzka, Steffen [Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany); Biener, Monika; Biener, Jürgen [Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 (United States); Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany)

    2016-06-30

    Graphical abstract: - Highlights: • Photothermal laser processing is used to modify the surface structure of nanoporous gold. • Laser-fabricated structures exhibit pore sizes in the range from 25 nm to 200 nm and higher. • Ru-dye-functionalized surface structures are used in surface-enhanced Raman spectroscopy (SERS) studies. • Raman peak intensities of N719, a commercial Ru-dye, exhibit a strong dependence on the pore size. • Maximum Raman peak intensities are observed for small pore sizes close to 25 nm. - Abstract: Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

  16. Desorption by Femtosecond Laser Pulses : An Electron-Hole Effect?

    OpenAIRE

    D. M., NEWNS; T. F., HEINZ; J. A., MISEWICH; IBM Research Division, T. J. Watson Research Center; IBM Research Division, T. J. Watson Research Center; IBM Research Division, T. J. Watson Research Center

    1992-01-01

    Desorption of molecules from metal surfaces induced by femtosecond visible laser pulses has been reported. Since the lattice temperature rise is insufficient to explain desorption, an electronic mechanism is clearly responsible. It is shown that a theory based on direct coupling between the center-of-mass degree of freedom of the adsorbate and the electron-hole excitations of the substrate provides a satisfactory explanation of the various experimental findings.

  17. Laser writing of single-crystalline gold substrates for surface enhanced Raman spectroscopy

    Science.gov (United States)

    Singh, Astha; Sharma, Geeta; Ranjan, Neeraj; Mittholiya, Kshitij; Bhatnagar, Anuj; Singh, B. P.; Mathur, Deepak; Vasa, Parinda

    2017-07-01

    Surface enhanced Raman scattering (SERS) spectroscopy, a powerful contemporary tool for studying low-concentration analytes via surface plasmon induced enhancement of local electric field, is of utility in biochemistry, material science, threat detection, and environmental studies. We have developed a simple, fast, scalable, and relatively low-cost optical method of fabricating and characterizing large-area, reusable and broadband SERS substrates with long storage lifetime. We use tightly focused, intense infra-red laser pulses to write gratings on single-crystalline, Au (1 1 1) gold films on mica which act as SERS substrates. Our single-crystalline SERS substrates compare favourably, in terms of surface quality and roughness, to those fabricated in poly-crystalline Au films. Tests show that our SERS substrates have the potential of detecting urea and 1,10-phenantroline adulterants in milk and water, respectively, at 0.01 ppm (or lower) concentrations.

  18. Desorption and ionization processes in laser mass spectrometry

    International Nuclear Information System (INIS)

    Peyl, G.J.Q. van der.

    1984-01-01

    In this thesis results are reported from a study on the desorption- and ionization process initiated by infra-red laser irradiation (LDMS) or ion bombardment (SIMS) of thin organic sample layers. The study is especially focused on the formation of quasimolecular ions under these conditions. Results of these investigations can be used for a better optimization of the LDMS and SIMS techniques in organic mass spectrometry. First, an overview is given of laser desorption mass spectrometry. Next, the coupling of the laser energy into the organic sample layer is investigated. It is concluded that the laser energy is primarily absorbed by the substrate material and not by the organic overlayer. The formation of quasi-molecular ions, either in the gas phase or in the substrate surface is investigated. The final section reports kinetic energy distributions for ions sputtered from organic solids and liquids. (Auth.)

  19. Overview literature on matrix assisted laser desorption ionization ...

    Indian Academy of Sciences (India)

    Unknown

    Overview literature on matrix assisted laser desorption ionization mass spectroscopy (MALDI MS): basics and its applications in characterizing polymeric materials. R N JAGTAP* and A H AMBRE. Polymer Engineering and Technology Department, University of Mumbai, Institute of Chemical Technology,. Mumbai 400 019 ...

  20. Surface-Enhanced Raman Scattering Activity of Ag/graphene/polymer Nanocomposite Films Synthesized by Laser Ablation

    Czech Academy of Sciences Publication Activity Database

    Siljanovska Petreska, G.; Blazevska-Gilev, J.; Fajgar, Radek; Tomovska, R.

    2014-01-01

    Roč. 564, AUG 1 (2014), s. 115-120 ISSN 0040-6090 Grant - others:NATO SfP(US) 984399 Institutional support: RVO:67985858 Keywords : laser ablation * surface-enhanced raman scattering * nanocomposite s * graphene * rhodamine 6G Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.759, year: 2014

  1. Investigations into ultraviolet matrix-assisted laser desorption

    Energy Technology Data Exchange (ETDEWEB)

    Heise, Theodore W. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    Matrix-assisted laser desorption (MALD) is a technique for converting large biomolecules into gas phase ions. Some characteristics of the commonly used uv matrices are determined. Solubilities in methanol range from 0.1 to 0.5 M. Solid phase absorption spectra are found to be similar to solution, but slightly red-shifted. Acoustic and quartz crystal microbalance signals are investigated as possible means of uv-MALD quantitation. Evidence for the existence of desorption thresholds is presented. Threshold values are determined to be in the range of 2 to 3 MW/cm2. A transient imaging technique based on laser-excited fluorescence for monitoring MALD plumes is described. Sensitivity is well within the levels required for studying matrix-assisted laser desorption, where analyte concentrations are significantly lower than those in conventional laser desorption. Results showing the effect of film morphology, particularly film thickness, on plume dynamics are presented. In particular, MALD plumes from thicker films tend to exhibit higher axial velocities. Fluorescent labeling of protein and of DNA is used to allow imaging of their uv-MALD generated plumes. Integrated concentrations are available with respect to time, making it possible to assess the rate of fragmentation. The spatial and temporal distributions are important for the design of secondary ionization schemes to enhance ion yields and for the optimization of ion collection in time-of-flight MS instruments to maximize resolution. Such information could also provide insight into whether ionization is closely associated with the desorption step or whether it is a result of subsequent collisions with the matrix gas (e.g., proton transfer). Although the present study involves plumes in a normal atmosphere, adaptation to measurements in vacuum (e.g., inside a mass spectrometer) should be straightforward.

  2. [Serum diagnosis of head and neck squamous cell carcinoma using surface-enhanced desorption ionization mass spectrometry and artificial neural network analyses].

    Science.gov (United States)

    Cao, Su-Mei; Guo, Xiang; Chen, Fu-Jin; Yang, An-Kui; Chen, Wen-Kuan; Li, Ning-Wei

    2007-07-01

    The early diagnosis of head and neck squamous cell carcinoma (HNSCC) is the key factor that affecting the treatment result. We performed surface-enhanced desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) using a multi-layer artificial neural network (ANN) to develop and evaluate a proteomic diagnosis approach for HNSCC. Serum samples from 74 HNSCC patients and 146 healthy individuals were randomized into training set (148 samples) and test set (72 samples). At first, we detected the training set of samples using SELDI mass spectrometry and WCX2 (weak cation-exchange) chips. Using a multi-layer ANN with a back propagation algorithm, we identified a proteomic pattern that could discriminate cancer from control samples in the training set. The discovered pattern was then used to determine the accuracy of the classification system in the test set. Four top-scored peaks, at m/z (mass/charge) ratio of 4 469 u, 5 924 u, 8 926 u, and 16 697 u, were finally selected as the potential biomarkers for detection of HNSCC with both sensitivity and specificity of 100.0% in the training set. The classifier predicted the HNSCC with sensitivity of 85.7%(18/21) and specificity of 96.1%(49/51) in the test set. SELDI profiling is a useful tool to accurately identify patients with HNSCC.

  3. Characterization and surface-enhanced Raman spectral probing of silver hydrosols prepared by two-wavelength laser ablation and fragmentation

    Czech Academy of Sciences Publication Activity Database

    Šmejkal, P.; Šišková, K.; Vlčková, B.; Pfleger, Jiří; Šloufová, Ivana; Šlouf, Miroslav; Mojzeš, P.

    2003-01-01

    Roč. 59, č. 10 (2003), s. 2321-2329 ISSN 1386-1425. [International Conference on Raman Spectroscopy Applied to the Earth Sciences /5./. Prague, 12.06.2002-15.06.2002] R&D Projects: GA ČR GA203/01/1013 Institutional research plan: CEZ:AV0Z4050913 Keywords : surface-enhanced Raman spectroscopy * silver hydrosols * two-wavelength laser ablation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.315, year: 2003

  4. Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Kostko, Oleg; Takahashi, Lynelle K.; Ahmed, Musahid

    2011-04-05

    There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly discussed.

  5. Gold nanolenses generated by laser ablation-efficient enhancing structure for surface enhanced Raman scattering analytics and sensing.

    Science.gov (United States)

    Kneipp, Janina; Li, Xiangting; Sherwood, Margaret; Panne, Ulrich; Kneipp, Harald; Stockman, Mark I; Kneipp, Katrin

    2008-06-01

    Nanoaggregates formed by metal spheres of different radii and interparticle distances represent finite, deterministic, self-similar systems that efficiently concentrate optical fields and act as "nanolenses". Here we verify experimentally the theoretical concept of nanolenses and explore their potential as enhancing nanostructures in surface enhanced Raman scattering (SERS). Self-similar structures formed by gold nanospheres of different sizes are generated by laser ablation from solid gold into water. These nanolenses exhibit SERS enhancement factors on the order of 10(9). The "chemically clean" preparation process provides several advantages over chemically prepared nanoaggregates and makes the stable and biocompatible gold nanolenses potent enhancing structures for various analytical and sensing applications.

  6. Laser desorption ionization and peptide sequencing on laser induced silicon microcolumn arrays

    Science.gov (United States)

    Vertes, Akos [Reston, VA; Chen, Yong [San Diego, CA

    2011-12-27

    The present invention provides a method of producing a laser-patterned silicon surface, especially silicon wafers for use in laser desorption ionization (LDI-MS) (including MALDI-MS and SELDI-MS), devices containing the same, and methods of testing samples employing the same. The surface is prepared by subjecting a silicon substrate to multiple laser shots from a high-power picosecond or femtosecond laser while in a processing environment, e.g., underwater, and generates a remarkable homogenous microcolumn array capable of providing an improved substrate for LDI-MS.

  7. Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Naoko Goto-Inoue

    2010-12-01

    Full Text Available Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS is a powerful tool that enables the simultaneous detection and identification of biomolecules in analytes. MALDI-imaging mass spectrometry (MALDI-IMS is a two-dimensional MALDI-mass spectrometric technique used to visualize the spatial distribution of biomolecules without extraction, purification, separation, or labeling of biological samples. MALDI-IMS has revealed the characteristic distribution of several biomolecules, including proteins, peptides, amino acids, lipids, carbohydrates, and nucleotides, in various tissues. The versatility of MALDI-IMS has opened a new frontier in several fields such as medicine, agriculture, biology, pharmacology, and pathology. MALDI-IMS has a great potential for discovery of unknown biomarkers. In this review, we describe the methodology and applications of MALDI-IMS for biological samples.

  8. Laser Desorption Mass Spectrometry for DNA Sequencing and Analysis

    Science.gov (United States)

    Chen, C. H. Winston; Taranenko, N. I.; Golovlev, V. V.; Isola, N. R.; Allman, S. L.

    1998-03-01

    Rapid DNA sequencing and/or analysis is critically important for biomedical research. In the past, gel electrophoresis has been the primary tool to achieve DNA analysis and sequencing. However, gel electrophoresis is a time-consuming and labor-extensive process. Recently, we have developed and used laser desorption mass spectrometry (LDMS) to achieve sequencing of ss-DNA longer than 100 nucleotides. With LDMS, we succeeded in sequencing DNA in seconds instead of hours or days required by gel electrophoresis. In addition to sequencing, we also applied LDMS for the detection of DNA probes for hybridization LDMS was also used to detect short tandem repeats for forensic applications. Clinical applications for disease diagnosis such as cystic fibrosis caused by base deletion and point mutation have also been demonstrated. Experimental details will be presented in the meeting. abstract.

  9. Ionization Mechanism of Matrix-Assisted Laser Desorption/Ionization

    Science.gov (United States)

    Lu, I.-Chung; Lee, Chuping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2015-07-01

    In past studies, mistakes in determining the ionization mechanism in matrix-assisted laser desorption/ionization (MALDI) were made because an inappropriate ion-to-neutral ratio was used. The ion-to-neutral ratio of the analyte differs substantially from that of the matrix in MALDI. However, these ratios were not carefully distinguished in previous studies. We begin by describing the properties of ion-to-neutral ratios and reviews early experimental measurements. A discussion of the errors committed in previous theoretical studies and a comparison of recent experimental measurements follow. We then describe a thermal proton transfer model and demonstrate how the model appropriately describes ion-to-neutral ratios and the total ion intensity. Arguments raised to challenge thermal ionization are then discussed. We demonstrate how none of the arguments are valid before concluding that thermal proton transfer must play a crucial role in the ionization process of MALDI.

  10. Laser desorption mass spectrometry for DNA analysis and sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.H.; Taranenko, N.I.; Tang, K.; Allman, S.L.

    1995-03-01

    Laser desorption mass spectrometry has been considered as a potential new method for fast DNA sequencing. Our approach is to use matrix-assisted laser desorption to produce parent ions of DNA segments and a time-of-flight mass spectrometer to identify the sizes of DNA segments. Thus, the approach is similar to gel electrophoresis sequencing using Sanger`s enzymatic method. However, gel, radioactive tagging, and dye labeling are not required. In addition, the sequencing process can possibly be finished within a few hundred microseconds instead of hours and days. In order to use mass spectrometry for fast DNA sequencing, the following three criteria need to be satisfied. They are (1) detection of large DNA segments, (2) sensitivity reaching the femtomole region, and (3) mass resolution good enough to separate DNA segments of a single nucleotide difference. It has been very difficult to detect large DNA segments by mass spectrometry before due to the fragile chemical properties of DNA and low detection sensitivity of DNA ions. We discovered several new matrices to increase the production of DNA ions. By innovative design of a mass spectrometer, we can increase the ion energy up to 45 KeV to enhance the detection sensitivity. Recently, we succeeded in detecting a DNA segment with 500 nucleotides. The sensitivity was 100 femtomole. Thus, we have fulfilled two key criteria for using mass spectrometry for fast DNA sequencing. The major effort in the near future is to improve the resolution. Different approaches are being pursued. When high resolution of mass spectrometry can be achieved and automation of sample preparation is developed, the sequencing speed to reach 500 megabases per year can be feasible.

  11. Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001)

    DEFF Research Database (Denmark)

    Frigge, R.; Hoger, T.; Siemer, B.

    2010-01-01

    Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states...... of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms-1 for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential....

  12. Detection of organic colorants in historical painting layers using UV laser ablation surface-enhanced Raman microspectroscopy.

    Science.gov (United States)

    Cesaratto, Anna; Leona, Marco; Lombardi, John R; Comelli, Daniela; Nevin, Austin; Londero, Pablo

    2014-12-22

    Surface-enhanced Raman spectroscopy (SERS) has been increasingly used in the study of works of art to identify organic pigments and dyes in paintings, which (depending on the material) are difficult or not possible to detect by other current methods. The application of SERS to the study of paintings has been limited, however, by the lack of a sampling approach with sufficient sensitivity and spatial resolution. We show that ultraviolet laser ablation (LA) sampling coupled with SERS detection can be successfully used to study paint layers. LA-SERS permitted the isolation of signals from colorants in individual thin paint layers in sample cross-sections, avoiding contamination from adjacent layers. These results expand the range of analytical applications of SERS demonstrating how the technique can be used to sensitively detect minor organic components in complex matrices. While this is fundamental for the study of cultural heritage, it is also relevant in other fields such as forensic analysis, food science, and pharmacology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Laser desorption mass spectrometry for fast DNA analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.H.; Ch`ang, L.Y.; Taranenko, N.I.; Allman, S.L.; Tang, K.; Matteson, K.J.

    1995-09-01

    During the past few years, major effort has been directed toward developing mass spectrometry to measure biopolymers because of the great potential benefit to biomedical research. Hellenkamp and his co-workers were the first to report that large polypeptide molecules can be ionized and detected without significant fragmentation when a greater number of nicotinic acid molecules are used as a matrix. This method is now well known as matrix-assisted laser desorption/ionization (MALDI). Since then, various groups have reported measurements of very large proteins by MALDI. Reliable protein analysis by MALDI is more or less well established. However, the application of MALDI to nucleic acids analysis has been found to be much more difficult. Most research on the measurement of nucleic acid by MALDI were stimulated by the Human Genome Project. Up to now, the only method for reliable routine analysis of nucleic acid is gel electrophoresis. Different sizes of nucleic acids can be separated in gel medium when a high electric field is applied to the gel. However, the time needed to separate different sizes of DNA segments usually takes from several minutes to several hours. If MALDI can be successfully used for nucleic acids analysis, the analysis time can be reduced to less than I millisecond. In addition, no tagging with radioactive materials or chemical dyes is needed. In this work, we will review recent progress related to MALDI for DNA analysis.

  14. Laser desorption mass spectrometry for point mutation detection

    Energy Technology Data Exchange (ETDEWEB)

    Taranenko, N.I.; Chung, C.N.; Zhu, Y.F. [Oak Ridge National Lab., TN (United States)] [and others

    1996-10-01

    A point mutation can be associated with the pathogenesis of inherited or acquired diseases. Laser desorption mass spectrometry coupled with allele specific polymerase chain reaction (PCR) was first used for point mutation detection. G551D is one of several mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene present in 1-3% of the mutant CFTR alleles in most European populations. In this work, two different approaches were pursued to detect G551D point mutation in the cystic fibrosis gene. The strategy is to amplify the desired region of DNA template by PCR using two primers that overlap one base at the site of the point mutation and which vary in size. If the two primers based on the normal sequence match the target DNA sequence, a normal PCR product will be produced. However, if the alternately sized primers that match the mutant sequence recognize the target DNA, an abnormal PCR product will be produced. Thus, the mass spectrometer can be used to identify patients that are homozygous normal, heterozygous for a mutation or homozygous abnormal at a mutation site. Another approach to identify similar mutations is the use of sequence specific restriction enzymes which respond to changes in the DNA sequence. Mass spectrometry is used to detect the length of the restriction fragments generated by digestion of a PCR generated target fragment. 21 refs., 10 figs., 2 tabs.

  15. Laser desorption mass spectrometry for point mutation detection

    Energy Technology Data Exchange (ETDEWEB)

    Taranenko, N.I.; Chung, C.N.; Zhu, Y.F. [Oak Ridge National Lab., TN (United States)] [and others

    1996-12-31

    A point mutation can be associated with the pathogenesis of inherited or acquired diseases. Laser desorption mass spectrometry coupled with allele specific polymerase chain reaction (PCR) was first used for point mutation detection. G551D is one of several mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene present in 1-3% of the mutant CFTR alleles in most European populations. In this work, two different approaches were pursued to detect G551D point mutation in the cystic fibrosis gene. The strategy is to amplify the desired region of DNA template by PCR using two primers that overlap one base at the site of the point mutation and which vary in size. If the two primers based on the normal sequence match the target DNA sequence, a normal PCR product will be produced. However, if the alternately sized primers that match the mutant sequence recognize the target DNA, an abnormal PCR product will be produced. Thus, the mass spectrometer can be used to identify patients that are homozygous normal, heterozygous for a mutation or homozygous abnormal at a mutation site. Another approach to identify similar mutations is the use of sequence specific restriction enzymes which respond to changes in the DNA sequence. Mass spectrometry is used to detect the length of the restriction fragments by digestion of a PCR generated target fragment. 21 refs., 10 figs., 2 tabs.

  16. Optical laser-induced CO desorption from Ru(0001) monitored with a free-electron X-ray laser

    DEFF Research Database (Denmark)

    Öberg, H.; Gladh, J.; Dell'Angela, M.

    2015-01-01

    (~1.4 eV at 2000 K). Experimental pump-probe X-ray absorption/X-ray emission spectroscopy indicates population of a precursor state to desorption upon laser-excitation of the system (Dell'Angela et al., 2013). Computing spectra along the desorption path confirms the picture of a weakly bound transient...

  17. Ambient Femtosecond Laser Vaporization and Nanosecond Laser Desorption Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Flanigan, Paul; Levis, Robert

    2014-06-01

    Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 1013 W cm-2 desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.

  18. Plasmon-less surface enhanced Raman spectra induced by self-organized networks of silica nanoparticles produced by femtosecond lasers.

    Science.gov (United States)

    Bellouard, Yves; Block, Erica; Squier, Jeff; Gobet, Jean

    2017-05-01

    Raman spectroscopy is the workhorse for label-free analysis of molecules. It relies on the inelastic scattering of incoming monochromatic light impinging molecules of interest. This effect leads to a very weak emission of light spectrum that provides a signature of the molecules being observed. Considerable efforts have been made over the last decades, in particular with the development of Surface Enhanced Raman Spectroscopy (SERS), to enhance the intensity of the emitted signal so that ultimately, traces of molecules can be detected. Here, we show that dense self-organized networks of quasi-monodisperse nanoparticles redepositing during femtosecond laser ablation of trenches in fused silica can lead to a significant field enhancement effect, enabling the Raman detection of a single-molecule layer deposited on the surface (so called monolayer). Unlike previously reported for SERS experiments, here, there is no metal layer promoting plasmonics effects causing localized field enhancement. The method for producing SERS substrates is therefore quite straightforward and low cost.

  19. Airborne laser-spark for ambient desorption/ionisation.

    Science.gov (United States)

    Bierstedt, Andreas; Riedel, Jens

    A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die

  20. Coupling laser desorption with gas chromatography and ion mobility spectrometry for improved olive oil characterisation.

    Science.gov (United States)

    Liedtke, Sascha; Seifert, Luzia; Ahlmann, Norman; Hariharan, Chandrasekhara; Franzke, Joachim; Vautz, Wolfgang

    2018-07-30

    The investigation of volatile compounds in the headspace of liquid samples can often be used for detailed and non-destructive characterisation of the sample. This has great potential for process control or the characterisation of food samples, such as olive oil. We investigated, for the first time, the plume of substances released from olive oil droplets by laser desorption in a feasibility study and applied ion mobility spectrometry coupled to rapid GC pre-separation to enhance selectivity. Our investigation demonstrated that significantly more substances can be detected and quantified via laser desorption than in the usual headspace, enabling a rapid (5-10 min), sensitive (low ng/g range) and comprehensive analysis of the sample, with the potential for quality control and fraud identification. Therefore, laser desorption provides a useful sampling tool for characterising liquids in many applications, requiring only a few µL of sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Surface-assisted laser desorption ionization mass spectrometry techniques for application in forensics.

    Science.gov (United States)

    Guinan, Taryn; Kirkbride, Paul; Pigou, Paul E; Ronci, Maurizio; Kobus, Hilton; Voelcker, Nicolas H

    2015-01-01

    Matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) is an excellent analytical technique for the rapid and sensitive analysis of macromolecules (>700 Da), such as peptides, proteins, nucleic acids, and synthetic polymers. However, the detection of smaller organic molecules with masses below 700 Da using MALDI-MS is challenging due to the appearance of matrix adducts and matrix fragment peaks in the same spectral range. Recently, nanostructured substrates have been developed that facilitate matrix-free laser desorption ionization (LDI), contributing to an emerging analytical paradigm referred to as surface-assisted laser desorption ionization (SALDI) MS. Since SALDI enables the detection of small organic molecules, it is rapidly growing in popularity, including in the field of forensics. At the same time, SALDI also holds significant potential as a high throughput analytical tool in roadside, work place and athlete drug testing. In this review, we discuss recent advances in SALDI techniques such as desorption ionization on porous silicon (DIOS), nano-initiator mass spectrometry (NIMS) and nano assisted laser desorption ionization (NALDI™) and compare their strengths and weaknesses with particular focus on forensic applications. These include the detection of illicit drug molecules and their metabolites in biological matrices and small molecule detection from forensic samples including banknotes and fingerprints. Finally, the review highlights recent advances in mass spectrometry imaging (MSI) using SALDI techniques. © 2014 Wiley Periodicals, Inc.

  2. Bioaerosol detection by aerosol TOF-mass spectrometry: Application of matrix assisted laser desorption/ionisation

    NARCIS (Netherlands)

    Wuijckhuijse, A.L. van; Stowers, M.A.; Kientz, Ch.E.; Marijnissen, J.C.M.; Scarlett, B.

    2000-01-01

    In previous publications the use of an aerosol time of flight mass spectrometer was reported for the on-line measurements of aerosols (Weiss 1997, Kievit 1995). The apparatus is capable of measuring the size as well as the chemical composition, by the use of Laser Desorption/Ionisation (LDI), of an

  3. Laser Desorption Mass Spectrometry for High Throughput DNA Analysis and Its Applications

    Energy Technology Data Exchange (ETDEWEB)

    Allman, S.L.; Chen, C.H.; Golovlev, V.V.; Isola, N.R.; Matteson, K.J.; Potter, N.T.; Taranenko, N.I.

    1999-01-23

    Laser desorption mass spectrometry (LDMS) has been developed for DNA sequencing, disease diagnosis, and DNA Fingerprinting for forensic applications. With LDMS, the speed of DNA analysis can be much faster than conventional gel electrophoresis. No dye or radioactive tagging to DNA segments for detection is needed. LDMS is emerging as a new alternative technology for DNA analysis.

  4. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    Science.gov (United States)

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  5. Laser desorption mass spectrometry for high-throughput DNA analysis and its applications

    Science.gov (United States)

    Chen, C. H. Winston; Golovlev, Valeri V.; Taranenko, N. I.; Allman, S. L.; Isola, Narayana R.; Potter, N. T.; Matteson, K. J.; Chang, Linus Y.

    1999-05-01

    Laser desorption mass spectrometry (LDMS) has been developed for DNA sequencing, disease diagnosis, and DNA fingerprinting for forensic applications. With LDMS, the speed of DNA analysis can be much faster than conventional gel electrophoresis. No dye or radioactive tagging to DNA segments for detection is needed. LDMS is emerging as a new alternative technology for DNA analysis.

  6. Laser desorption and time-of-flight mass spectrometry. Fundamentals .Applications; Desorption laser et spectrometrie de masse par temps de vol. Aspects fondamentaux. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chaurand, P.

    1994-11-01

    Time-of-flight mass spectrometry is a very powerful technique for the analysis of heavy molecular ions (100 000 u and more). The ejection in the gas phase and the ionization of these molecules is now possible through the MALDI technique (Matrix Assisted Laser Desorption Ionization). This technique consists in mixing the heavy molecules to be analysed with a organic matrix which absorbs at the wavelength of the laser. The necessary irradiance are of the order of 10{sup 6} W/cm{sup 2}. In these conditions we have shown that the mass resolutions are optimum and that the relative mass accuracies are of the order of 10{sup -4}. We have also demonstrated that the emission angle of the molecular ions in MALDI depends on the incident angle of the laser light. During the desorption process, the molecular ions are emitted in the opposite direction of the incident laser light. This effect is particularly important for the design of the accelerating stage of the time-of-flight spectrometers. Problems relative to the detection of these heavy molecular ions have been studied in details between 0.5 10{sup 4} m/s and 10{sup 5} m/s. The velocity threshold of the electronic emission is lower than the value of 0.5 10{sup 4} m/s. The relation between the electronic emission and the projectile velocity is complex. Finally, examples on mass identification of C{sub 60} molecules and derivated C{sub 60} are presented. Desorption methods are compared. (author). 32 refs., 34 figs.

  7. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

    2007-04-15

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12{+-}1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3x{omega} Nd:YAG laser in air, SF{sub 6} or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

  8. Laser-induced desorption of organic molecules from front- and back-irradiated metal foils

    International Nuclear Information System (INIS)

    Zinovev, Alexander V.; Veryovkin, Igor V.; Pellin, Michael J.

    2009-01-01

    Laser-Induced Acoustic Desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the Single Photon Ionization (SPI) method combined with time-of-flight mass-spectrometry (TOF MS), desorbed flux in LIAD was examined and compared to that from direct laser desorption (LD). Molecules of various organic dyes were used in experiments. Translational velocities of the desorbed intact molecules did not depend on the desorbing laser intensity, which implies the presence of more sophisticated mechanism of energy transfer than the direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. The results of our experiments indicate that the LIAD phenomenon cannot be described in terms of a simple mechanical shake-off nor the direct laser desorption. Rather, they suggest that multi-step energy transfer processes are involved. Possible qualitative mechanism of LIAD that are based on formation of non-equilibrium energy states in the adsorbate-substrate system are proposed and discussed.

  9. Surface profiling of lithium with a laser-desorption mass-spectrometer microprobe

    International Nuclear Information System (INIS)

    Bickel, G.A.; Adams, H.M.

    1999-01-01

    A laser-desorption mass-spectrometer microprobe has been developed to profile Li distributions on the crevice surfaces of Cr-plated rolled-joint hubs. A single laser pulse is used to desorb and ionize the surface species followed by detection of Li + in a time-of-flight mass spectrometer. Images of the surface Li distribution are obtained with are solution of <10 μm. These images are directly compared with Li images from the more conventional secondary ion mass spectrometry technique and evaluated with respect to surface topographical features measured by secondary electron microscopy and atomic force microscopy. The laser-desorption images are shown to provide the same qualitative information as that available from secondary ion mass spectrometry. (author)

  10. Towards matrix-free femtosecond-laser desorption mass spectrometry for in situ space research.

    Science.gov (United States)

    Moreno-García, Pavel; Grimaudo, Valentine; Riedo, Andreas; Tulej, Marek; Wurz, Peter; Broekmann, Peter

    2016-04-30

    There is an increasing interest in the quest for low molecular weight biomarkers that can be studied on extra-terrestrial objects by direct laser desorption mass spectrometry (LD-MS). Although molecular structure investigations have recently been carried out by direct LD-MS approaches, there is still a lack of suitable instruments for implementation on a spacecraft due to weight, size and power consumption demands. In this contribution we demonstrate the feasibility of LD-MS structural analysis of molecular species by a miniature laser desorption-ionization mass spectrometer (instrument name LMS) originally designed for in situ elemental and isotope analysis of solids in space research. Direct LD-MS studies with molecular resolution were carried out by means of a Laser Ablation/Ionization Mass Spectrometry (LIMS) technique. Two polymer samples served as model systems: neutral polyethylene glycol (PEG) and cationic polymerizates of imidazole and epichlorohydrin (IMEP). Optimal conditions for molecular fragmentation could be identified for both polymers by tuning the laser energy and the instrument-sample distance. PEG and IMEP polymers show sufficient stability over a relatively wide laser energy range. Under mild LD conditions only moderate fragmentation of the polymers takes place so that valuable structural characterization based on fragment ions can be achieved. As the applied laser pulse energy rises, the abundance of fragment ions increases, reaches a plateau and subsequently drops down due to more severe fragmentation and atomization of the polymers. At this final stage, usually referred to as laser ablation, only elemental/isotope analysis can be achieved. Our investigations demonstrate the versatility of the LMS instrument that can be tuned to favourable laser desorption conditions that successfully meet molecule-specific requirements and deliver abundant fragment ion signals with detailed structural information. Overall, the results show promise for use in

  11. Laser desorption and time-of-flight mass spectrometry. Fundamentals .Applications

    International Nuclear Information System (INIS)

    Chaurand, P.

    1994-11-01

    Time-of-flight mass spectrometry is a very powerful technique for the analysis of heavy molecular ions (100 000 u and more). The ejection in the gas phase and the ionization of these molecules is now possible through the MALDI technique (Matrix Assisted Laser Desorption Ionization). This technique consists in mixing the heavy molecules to be analysed with a organic matrix which absorbs at the wavelength of the laser. The necessary irradiance are of the order of 10 6 W/cm 2 . In these conditions we have shown that the mass resolutions are optimum and that the relative mass accuracies are of the order of 10 -4 . We have also demonstrated that the emission angle of the molecular ions in MALDI depends on the incident angle of the laser light. During the desorption process, the molecular ions are emitted in the opposite direction of the incident laser light. This effect is particularly important for the design of the accelerating stage of the time-of-flight spectrometers. Problems relative to the detection of these heavy molecular ions have been studied in details between 0.5 10 4 m/s and 10 5 m/s. The velocity threshold of the electronic emission is lower than the value of 0.5 10 4 m/s. The relation between the electronic emission and the projectile velocity is complex. Finally, examples on mass identification of C 60 molecules and derivated C 60 are presented. Desorption methods are compared. (author). 32 refs., 34 figs

  12. Surface enhanced thermo lithography

    KAUST Repository

    Coluccio, Maria Laura

    2017-01-13

    We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a conventional Raman set-up to transfer geometrical patterns from a template of metal NPs clusters into a layer of thermo sensitive Polyphthalaldehyde (PPA) polymer. Temperature profile on the devices depends on specific arrangements of silver nanoparticles. In plane temperature variations may be controlled with (i) high nano-meter spatial precision and (ii) single Kelvin temperature resolution on varying the shape, size and spacing of metal nanostructures. This scheme can be used to generate strongly localized heat amplifications for applications in nanotechnology, surface enhanced thermo-lithography (SETL), biology and medicine (for space resolved cell ablation and treatment), nano-chemistry.

  13. Silver nanoparticles as matrix for laser desorption/ionization mass spectrometry of peptides

    International Nuclear Information System (INIS)

    Hua Lin; Chen Jianrong; Ge Liya; Tan, Swee Ngin

    2007-01-01

    Silver nanoparticle synthesized from chemical reduction has been successfully utilized as a matrix in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of peptides. Acting as a substrate to adsorb analytes, as well as a transmission medium for UV laser, silver nanoparticle was found to assist in the desorption/ionization of peptides with little or no induced fragmentation. The size of the nanoparticle was typically in the range of 160 ± 20 nm. One of the key advantages of silver nanoparticle for peptides analysis is its simple step for on-probe sample preparation. In addition, it also minimizes the interferences of sodium dodecyl sulfate (SDS) surfactant background signal, resulting in cleaner mass spectra and more sensitive signal, when compared to α-cyano-4-hydroxycinnamic acid (CCA) matrix

  14. Fossil fuel characterization using laser desorption mass spectrometry: Applications and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, J.E.; Winans, R.E.

    1995-08-01

    Laser desorption mass spectroscopy (LDMS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI) are applicable to the high molecular weight compounds in fossil fuels which resist intact ionization. LD or MALDI of coals and extracts do not show reproducible ion intensity over mass 2000. This paper describes the scope and limitations of LD and MALD in time-of-flight mass spectrometers applied to high molecular weight molecules such as proteins and polymers. Coal was also analyzed. It is concluded that the sample preparation step is perhaps the most important part in MALDI. Observed high mass ions in coal may be from contaminant proteins. Optimal matrices must be found. Finally, the mass spectrum is senstive to number average molecular weight; a low value, however, does not preclude presence of high molecular weight species.

  15. Influence of fs-laser desorption on target normal sheath accelerated ions

    Directory of Open Access Journals (Sweden)

    G. Hoffmeister

    2013-04-01

    Full Text Available We report on the effects of fs-laser desorption on the ion acceleration induced by the target normal sheath acceleration (TNSA mechanism. The experiment was performed at the Lawrence Livermore National Laboratory (LLNL using the 100 TW Callisto laser of the Jupiter Laser Facility (JLF. Thin metal foils (Au, Cu, and Al with thicknesses ranging from 10 to 20  μm were irradiated by a variable number of low intensity (∼10^{12}  W/cm^{2} laser pulses, the last one arriving 100 ms before the main pulse. With these short pulses water vapor and hydrocarbon contaminations could stepwise be removed from the target surface. Substantial modifications of the TNSA-ion energy spectra were observed such as diminished proton energy and intensity, the absence of low-charged ion states, increased particle numbers for C^{4+} and O^{6+} ions in the higher energetic part of their particle spectra as well as the acceleration of target ions. The controlled application of fs-laser desorption on the laser-ion acceleration thus strongly influences the ion spectra and offers the possibility of selecting a targeted range of ion species for the acceleration to higher energies due to the systematic removal of contamination layers.

  16. The Examination of Synthetic Organic Pigments in Modern Works of Art by Raman Microscopy and Laser Desorption Ionziation Mass Spectrometry

    Science.gov (United States)

    Lomax, S. Q.; Lomax, J. F.; De-Luca Westrate, A.

    2014-06-01

    Raman spectroscopy in combination with laser desorption ionization mass spectrometry was used to examine samples from modern works of art by artists including Mark Rothko, Barnett Newman, and José de Rivera to identify the pigments present.

  17. Matrix-assisted laser desorption and electrospray ionization mass spectrometry of carminic acid isolated from cochineal

    Science.gov (United States)

    Maier, Marta S.; Parera, Sara D.; Seldes, Alicia M.

    2004-04-01

    Carminic acid, isolated from cochineal, was analyzed by matrix-assisted laser desorption/ionization (MALDI) and electrospray mass spectrometry (ESI-MS). Application of both techniques to the analysis of carminic acid suspended in linseed oil and applied to a piece of canvas, demonstrated the ability of MALDI and ESI-MS to identify this organic dye in a mixture as those used in easel painting.

  18. Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

    DEFF Research Database (Denmark)

    Andersen, Jens S.; Svensson, B; Roepstorff, P

    1996-01-01

    Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...

  19. Matrix-assisted laser desorption fourier transform mass spectrometry for biological compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hettich, R.; Buchanan, M.

    1990-01-01

    The recent development of matrix-assisted UV laser desorption (LD) mass spectrometry has made possible the ionization and detection of extremely large molecules (with molecular weights exceeding 100,000 Daltons). This technique has generated enormous interest in the biological community for the direct examination of large peptides and oligonucleotides. Although this matrix-assisted ionization method has been developed and used almost exclusively with time-of-flight (TOF) mass spectrometers, research is currently in progress to demonstrate this technique with trapped ion mass spectrometers, such as Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The potential capabilities of FTMS for wide mass range, high resolution measurement, and ion trapping experiments suggest that this instrumental technique should be useful for the detailed structural characterization of large ions generated by the matrix-assisted technique. We have recently demonstrated that matrix-assisted ultraviolet laser desorption can be successfully used with FTMS for the ionization of small peptides. The objective of this report is to summarize the application and current limitations of matrix-assisted laser desorption FTMS for the characterization of peptides and oligonucleotides at the isomeric level. 4 refs., 3 figs., 2 tabs.

  20. Laser-Modified Surface Enhances Osseointegration and Biomechanical Anchorage of Commercially Pure Titanium Implants for Bone-Anchored Hearing Systems

    Science.gov (United States)

    Omar, Omar; Simonsson, Hanna; Palmquist, Anders; Thomsen, Peter

    2016-01-01

    Osseointegrated implants inserted in the temporal bone are a vital component of bone-anchored hearing systems (BAHS). Despite low implant failure levels, early loading protocols and simplified procedures necessitate the application of implants which promote bone formation, bone bonding and biomechanical stability. Here, screw-shaped, commercially pure titanium implants were selectively laser ablated within the thread valley using an Nd:YAG laser to produce a microtopography with a superimposed nanotexture and a thickened surface oxide layer. State-of-the-art machined implants served as controls. After eight weeks’ implantation in rabbit tibiae, resonance frequency analysis (RFA) values increased from insertion to retrieval for both implant types, while removal torque (RTQ) measurements showed 153% higher biomechanical anchorage of the laser-modified implants. Comparably high bone area (BA) and bone-implant contact (BIC) were recorded for both implant types but with distinctly different failure patterns following biomechanical testing. Fracture lines appeared within the bone ~30–50 μm from the laser-modified surface, while separation occurred at the bone-implant interface for the machined surface. Strong correlations were found between RTQ and BIC and between RFA at retrieval and BA. In the endosteal threads, where all the bone had formed de novo, the extracellular matrix composition, the mineralised bone area and osteocyte densities were comparable for the two types of implant. Using resin cast etching, osteocyte canaliculi were observed directly approaching the laser-modified implant surface. Transmission electron microscopy showed canaliculi in close proximity to the laser-modified surface, in addition to a highly ordered arrangement of collagen fibrils aligned parallel to the implant surface contour. It is concluded that the physico-chemical surface properties of laser-modified surfaces (thicker oxide, micro- and nanoscale texture) promote bone bonding

  1. Brominated Tyrosine and Polyelectrolyte Multilayer Analysis by Laser Desorption VUV Postionization and Secondary Ion Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    University of Illinois at Chicago; Blaze, Melvin M. T.; Takahashi, Lynelle; Zhou, Jia; Ahmed, Musahid; Gasper, Gerald; Pleticha, F. Douglas; Hanley, Luke

    2011-03-14

    The small molecular analyte 3,5-dibromotyrosine (Br2Y) and chitosan-alginate polyelectrolyte multilayers (PEM) with and without adsorbed Br2Y were analyzed by laser desorption postionization mass spectrometry (LDPI-MS). LDPI-MS using 7.87 eV laser and tunable 8 ? 12.5 eV synchrotron vacuum ultraviolet (VUV) radiation found that desorption of clusters from Br2Y films allowed detection by≤8 eV single photon ionization. Thermal desorption and electronic structure calculations determined the ionization energy of Br2Y to be ~;;8.3?0.1 eV and further indicated that the lower ionization energies of clusters permitted their detection at≤8 eV photon energies. However, single photon ionization could only detect Br2Y adsorbed within PEMs when using either higher photon energies or matrix addition to the sample. All samples were also analyzed by 25 keV Bi3 + secondary ion mass spectrometry (SIMS), with the negative ion spectra showing strong parent ion signal which complemented that observed by LDPI-MS. The negative ion SIMS depended strongly on the high electron affinity of this specific analyte and the analyte?s condensed phase environment.

  2. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

    Science.gov (United States)

    Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

  3. Laser-induced construction of multi-branched CuS nanodendrites with excellent surface-enhanced Raman scattering spectroscopy in repeated applications.

    Science.gov (United States)

    Li, Shuang; Zhang, Hua; Xu, Linlin; Chen, Ming

    2017-07-10

    We report on the successful fabrication of multi-branched CuS nanodendrites with average branch length of about 20 nm by laser ablation of bulk Cu target in thioacetamide (TAA) solution. During the nucleation of Cu and S species, the accurate anisotropic growth should be attributed to an ultra-rapid acid etching process by laser-induced TAA hydrolyzing reaction. Interestingly, the semiconductor CuS nanodendrites provide pronounced surface enhanced Raman scattering (SERS) properties with noble-metal comparable activity and a detection limit as low as ~10 -10 M, approaching the requirement (~nM) for single molecule detection. More importantly, after SERS analysis, the crystal violet (CV) probe molecules can be effectively removed from the substrate by 1064nm laser irradiation-induced moderate thermal treatment. Therefore, the unique and distinctive advantage is that the as-prepared CuS nanodendrites exhibit excellent reusability for 60 cycles of repeated SERS analyses. The low-cost CuS semiconductor nanodendrites with enhanced SERS properties should be established as a prominent SERS-based ultrasensitive probe in the repeated applications.

  4. Surface enhanced 316L/SiC nano-composite coatings via laser cladding and following cold-swaging process

    Science.gov (United States)

    Li, Yuhang; Gao, Shiyou

    2017-10-01

    Cold-swaging is one of a cold deformation processes, and ceramic-reinforcement nano-composite coatings can effectively improve the performance of metal matrix surface. Therefore, the two processes are innovatively combined to further improve the surface properties of the metal matrix in this paper. The microstructure and surface properties of the laser cladding 316L + 10 wt% SiC nano-composite coatings were examined through designed experiments after cold-swaging by self-developed hydraulic machine. Furthermore, the coatings were compared with those without cold-swaging coatings at the same time. The result shows that the cold-swaging process can further enhance the tensile strength, micro-hardness and the wear resistance of the composite coating. This study can be used as a reference for further strengthening of laser cladding nano-composite coatings in future research.

  5. Laser Desorption of Tryptophan from Tryptophan-HCl Salt on a Graphite Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Jun; Kim, Jeong Jin; Kang, Hyuk [Ajou University, Suwon (Korea, Republic of)

    2016-03-15

    Laser spectroscopy of biological molecules in the gas phase has been pioneered by Levy and coworkers when they first produced a supersonic molecular beam of tryptophan (Trp) and obtained its electronic spectrum. They were able to obtain enough vapor pressure needed for spectroscopy by heating a powder sample of Trp, although a special thermal spray was used to minimize fragmentation during heating. Many amine compounds, including biomolecules like amino acids and peptides, are usually available only as HCl salt form in order to prevent oxidation in air. Chemical processing is required to recover a neutral amine compound from its salt, thus limiting the applicability of laser-desorption spectroscopy of biomolecules. The experimental setup is a standard molecular beam machine composed of a pulsed valve with a laser-desorption module in a vacuum chamber, a second buffer chamber, a skimmer that separates the first and the second chambers, and a third vacuum chamber that is a time-of-flight mass spectrometer (TOF MS)

  6. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F; Hanley, Luke

    2010-08-04

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.

  7. Cosmetic Analysis Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI

    Directory of Open Access Journals (Sweden)

    Rodrigo Ramos Catharino

    2013-03-01

    Full Text Available A new “omic” platform—Cosmetomics—that proves to be extremely simple and effective in terms of sample preparation and readiness for data acquisition/interpretation is presented. This novel approach employing Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI for cosmetic analysis has proven to readily identify and quantify compounds of interest. It also allows full control of all the production phases, as well as of the final product, by integration of both analytical and statistical data. This work has focused on products of daily use, namely nail polish, lipsticks and eyeliners of multiple brands sold in the worldwide market.

  8. Desorption/ablation of lithium fluoride induced by extreme ultraviolet laser radiation

    Czech Academy of Sciences Publication Activity Database

    Blejchař, T.; Nevrlý, V.; Vašinek, M.; Dostál, M.; Kozubková, M.; Dlabka, J.; Stachoň, M.; Juha, Libor; Bitala, P.; Zelinger, Zdeněk; Pira, Peter; Wild, J.

    2016-01-01

    Roč. 61, č. 2 (2016), s. 131-138 ISSN 0029-5922. [PLASMA 2015 : International Conference on Research and Applications of Plasmas. Warsaw, 07.09.2015-11.09.2015] R&D Projects: GA ČR(CZ) GAP108/11/1312 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : desorption * fluid dynamics * lithium fluoride * numerical simulation * plume expansion * pulsed laser ablation Subject RIV: BL - Plasma and Gas Discharge Physics; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 0.760, year: 2016

  9. Investigation of thin ZnO layers in view of laser desorption-ionization

    Energy Technology Data Exchange (ETDEWEB)

    Grechnikov, A A; Borodkov, A S [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow (Russian Federation); Georgieva, V B [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Alimpiev, S S; Nikiforov, S M; Simanovsky, Ya O [General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow (Russian Federation); Dimova-Malinovska, D; Angelov, O I, E-mail: lazarova@issp.bas.b [Laboratory for Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  10. Drawing a different picture with pencil lead as matrix-assisted laser desorption/ionization matrix for fullerene derivatives.

    Science.gov (United States)

    Nye, Leanne C; Hungerbühler, Hartmut; Drewello, Thomas

    2018-02-01

    Inspired by reports on the use of pencil lead as a matrix-assisted laser desorption/ionization matrix, paving the way towards matrix-free matrix-assisted laser desorption/ionization, the present investigation evaluates its usage with organic fullerene derivatives. Currently, this class of compounds is best analysed using the electron transfer matrix trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene] malononitrile (DCTB), which was employed as the standard here. The suitability of pencil lead was additionally compared to direct (i.e. no matrix) laser desorption/ionization-mass spectrometry. The use of (DCTB) was identified as the by far gentler method, producing spectra with abundant molecular ion signals and much reduced fragmentation. Analytically, pencil lead was found to be ineffective as a matrix, however, appears to be an extremely easy and inexpensive method for producing sodium and potassium adducts.

  11. Interpretation of laser desorption mass spectra of unexpected inorganic species found in a cosmetic sample of forensic interest: fingernail polish.

    Science.gov (United States)

    O'Neill, Emily; Harrington, Danielle; Allison, John

    2009-08-01

    When analytes containing color are irradiated with a pulsed UV laser in the ion source of a mass spectrometer, molecules such as dyes or pigments absorb energy, resulting in their desorption and ionization. This method, laser desorption mass spectrometry (LDMS), has been used successfully to analyze colorants of forensic interest in a wide variety of materials. Here, we present and interpret the most complex of such spectra obtained to date from a sample of fingernail polish. Interpretation of the spectrum provides a unique opportunity to characterize the laser desorption mass spectra of some unexpected inorganic materials found in cosmetics, such as "broken glass", cyanide compounds, and heavy metals. Also, the possibility of a useful forensic database of LDMS spectra of fingernail polishes is considered.

  12. Incoherent production reactions of positive and negative ions in matrix-assisted laser desorption/ionization.

    Science.gov (United States)

    Liu, Bo-Hong; Lee, Yuan Tseh; Wang, Yi-Sheng

    2009-06-01

    Utilizing synchronized dual-polarity matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, we found good evidence of the incoherent production of positive and negative matrix ions. Using thin, homogeneous 2,5-dehydroxybenzoic acid (DHB) matrix films, positive and negative matrix ions were found to appear at different threshold laser fluences. The presence of molecular matrix ions of single charge polarity suggests that the existence of DHB ion-pairs may not be a prerequisite in MALDI. Photoelectrons induced by the laser excitation may assist the production of negative DHB ions, as shown in experiments conducted with stainless steel and glass substrates. At high laser fluences, the relative yield of positive and negative matrix ions remained constant when homogeneous matrix films were used, but it fluctuated significantly with inhomogeneous crystal morphology. This result is also inconsistent with the hypothesis that matrix ion-pairs are essential primary ions. Evidence from both low and high laser fluences suggests that the productions of positive and negative matrix ions in MALDI may occur via independent pathways.

  13. Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jill R. Scott; Beizhan Yan; Daphne L. Stoner; J. Michelle Kotler; Nancy W. Hinman

    2007-04-01

    Identification of mineral-associated biosignatures is of significance for retrieving biochemical information from geological records here on Earth and detecting signs of life on other planets, such as Mars. The importance of the geomatrix for identifying amino acids (e.g., histidine, threonine, and cysteine) and small proteins (e.g., gramicidin S) was investigated by laser desorption Fourier transform mass spectrometry. The investigated geomatrices include analogues of Fe-bearing minerals such as hematite and Na-bearing evaporites (e.g., halite). Samples were prepared by two methods: 1) application of analyte to the geomatrix surface and 2) production of homogenous analyte:geomatrix mixtures. Comparison of the two sample preparation methods revealed that the mixing method produces a better signal/noise ratio than surface application for the analyses of amino acids. The composition of the geomatrix has a profound influence on the detection of biomolecules. Peaks corresponding to the cation-attached biomolecular ions were observed for the Na-bearing evaporite analogue. No detectable peaks for the biomolecular ion species were observed when the biomolecules were associated with Fe-bearing minerals. Instead, only minor peaks were observed that may correspond to ions from fragments of the biomolecules. Depending on the underlying mineral composition, geomatrix-assisted laser desorption/ionization shows promise for directly identifying biosignatures associated with minerals.

  14. Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

    International Nuclear Information System (INIS)

    Najam-ul-Haq, M.; Rainer, M.; Schwarzenauer, T.; Huck, C.W.; Bonn, G.K.

    2006-01-01

    Biomarkers play a potential role in the early detection and diagnosis of a disease. Our aim is to derivatize carbon nanotubes for exploration of the differences in human body fluids e.g. serum, through matrix assisted laser desorption ionisation/time of flight mass spectrometry (MALDI/TOF-MS) that can be related to disease and subsequently to be employed in the biomarker discovery process. This application we termed as the material enhanced laser desorption ionisation (MELDI). The versatility of this technology is meant to increase the amount of information from biological samples on the protein level, which will have a major impact to serve the cause of diagnostic markers. Serum peptides and proteins are immobilized on derivatized carbon nanotubes, which function as binding material. Protein-loaded suspension is placed on a stainless steel target or buckypaper on aluminum target for direct analysis with MALDI-MS. The elution method to wash the bound proteins from carbon nanotubes was employed to compare with the direct analysis procedure. Elution is carried out by MALDI matrix solution to get them out of the entangled nanotubes, which are difficult to desorb by laser due to the complex nanotube structures. The advantage of these optimized methods compared to the conventional screening methods is the improved sensitivity, selectivity and the short analysis time without prior albumin and immunoglobulin depletion. The comparison of similarly modified diamond and carbon nanotubes exhibit differences in their nature to bind the proteins out of serum due to the differences in their physical characteristics. Infrared (IR) spectroscopy provided hint for the presence of tertiary amine peak at the crucial chemical step of iminodiacetic acid addition to acid chloride functionality on carbon nanotubes. Atomic absorption spectroscopy (AAS) was utilized to quantitatively measure the copper capacity of these derivatized carbon nanotubes which is a direct measure of capacity of

  15. Detection of trace ink compounds in erased handwritings using electrospray-assisted laser desorption ionization mass spectrometry.

    Science.gov (United States)

    Kao, Yi-Ying; Cheng, Sy-Chyi; Cheng, Chu-Nian; Shiea, Jentaie; Ho, Hsiu-O

    2014-06-01

    Writings made with erasable pens on paper surfaces can either be rubbed off with an eraser or rendered invisible by changing the temperature of the ink. However, trace ink compounds still remain in the paper fibers even after rubbing or rendering. The detection of these ink compounds from erased handwritings will be helpful in knowing the written history of the paper. In this study, electrospray-assisted laser desorption ionization/mass spectrometry was used to characterize trace ink compounds remaining in visible and invisible ink lines. The ink compounds were desorbed from the paper surface by irradiating the handwritings with a pulsed laser beam; the desorbed analytes were subsequently ionized in an electrospray plume and detected by a quadrupole time-of-flight mass spectrometry mass analyzer. Because of the high spatial resolution of the laser beam, electrospray-assisted laser desorption ionization/mass spectrometry analysis resulted in minimal damage to the sample documents. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS): peering into the cup of Jamshid.

    Science.gov (United States)

    Valentino, L A

    2014-05-01

    The complex process underlying the development of blood-induced joint disease remains mysterious. Novel technologies such as matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) to examine protein signatures may provide clues into the process. © 2014 John Wiley & Sons Ltd.

  17. Development of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) for plant metabolite analysis

    Energy Technology Data Exchange (ETDEWEB)

    Korte, Andrew R [Iowa State Univ., Ames, IA (United States)

    2014-12-01

    This thesis presents efforts to improve the methodology of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) as a method for analysis of metabolites from plant tissue samples. The first chapter consists of a general introduction to the technique of MALDI-MSI, and the sixth and final chapter provides a brief summary and an outlook on future work.

  18. Phenotypic identification of Porphyromonas gingivalis validated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    NARCIS (Netherlands)

    Rams, Thomas E; Sautter, Jacqueline D; Getreu, Adam; van Winkelhoff, Arie J

    OBJECTIVE: Porphyromonas gingivalis is a major bacterial pathogen in human periodontitis. This study used matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to assess the accuracy of a rapid phenotypic identification scheme for detection of cultivable P.

  19. Laser-induced desorption determinations of surface diffusion on Rh(111)

    International Nuclear Information System (INIS)

    Seebauer, E.G.; Schmidt, L.D.

    1987-01-01

    Surface diffusion of hydrogen, deuterium and CO on Rh(111) has been investigated by laser-induced thermal desorption (LITD) and compared with previous results for these species on Pt(111) and on other metals. For deuterium in the coverage range 0.02 0 - 8 x 10 -2 cm 2 /s, with a diffusion activation energy 3.7 0 rises from 10 -3 to 10 -2 cm 2 /s between θ = 0.01 and 0.40. Values of E/sub diff/ on different surfaces appear to correlate with differences in heats of adsorption in different binding states which form saddle point configurations in surface diffusion. In addition, oxidation reactions on Rh and on several other transition metal surfaces may be limited to CO or H surface diffusion. 30 refs., 3 figs., 1 tab

  20. MALDI (matrix assisted laser desorption ionization) Imaging Mass Spectrometry (IMS) of skin: Aspects of sample preparation.

    Science.gov (United States)

    de Macedo, Cristiana Santos; Anderson, David M; Schey, Kevin L

    2017-11-01

    MALDI (matrix assisted laser desorption ionization) Imaging Mass Spectrometry (IMS) allows molecular analysis of biological materials making possible the identification and localization of molecules in tissues, and has been applied to address many questions on skin pathophysiology, as well as on studies about drug absorption and metabolism. Sample preparation for MALDI IMS is the most important part of the workflow, comprising specimen collection and preservation, tissue embedding, cryosectioning, washing, and matrix application. These steps must be carefully optimized for specific analytes of interest (lipids, proteins, drugs, etc.), representing a challenge for skin analysis. In this review, critical parameters for MALDI IMS sample preparation of skin samples will be described. In addition, specific applications of MALDI IMS of skin samples will be presented including wound healing, neoplasia, and infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Direct Surface Analysis of Fungal Species by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, Nancy B.(BATTELLE (PACIFIC NW LAB)); Wahl, Jon H.(BATTELLE (PACIFIC NW LAB)); Kingsley, Mark T.(BATTELLE (PACIFIC NW LAB)); Wahl, Karen L.(BATTELLE (PACIFIC NW LAB))

    2001-12-01

    Intact spores and/or hyphae of Aspergillus niger, Rhizopus oryzae, Trichoderma reesei and Phanerochaete chrysosporium are analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This study investigates various methods of sample preparation and matrices to determine optimum collection and analysis criteria for fungal analysis by MALDI-MS. Fungi are applied to the MALDI sample target as untreated, sonicated, acid/heat treated, or blotted directly from the fungal culture with double-stick tape. Ferulic acid or sinapinic acid matrix solution is layered over the dried samples and analyzed by MALDI-MS. Statistical analysis of the data show that simply using double stick tape to collect and transfer to a MALDI sample plate typically worked as well as the other preparation methods, but requires the least sample handling.

  2. A Simple Sonication Improves Protein Signal in Matrix-Assisted Laser Desorption Ionization Imaging

    Science.gov (United States)

    Lin, Li-En; Su, Pin-Rui; Wu, Hsin-Yi; Hsu, Cheng-Chih

    2018-02-01

    Proper matrix application is crucial in obtaining high quality matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI). Solvent-free sublimation was essentially introduced as an approach of homogeneous coating that gives small crystal size of the organic matrix. However, sublimation has lower extraction efficiency of analytes. Here, we present that a simple sonication step after the hydration in standard sublimation protocol significantly enhances the sensitivity of MALDI MSI. This modified procedure uses a common laboratory ultrasonicator to immobilize the analytes from tissue sections without noticeable delocalization. Improved imaging quality with additional peaks above 10 kDa in the spectra was thus obtained upon sonication treatment. [Figure not available: see fulltext.

  3. Laser desorption ionization mass spectrometry of peptides on a hybrid CHCA organic-inorganic matrix.

    Science.gov (United States)

    Fleith, Clément; Cantel, Sonia; Subra, Gilles; Mehdi, Ahmad; Ciccione, Jeremie; Martinez, Jean; Enjalbal, Christine

    2014-08-07

    We report applications of new hybrid organic-inorganic silica based materials as laser desorption/ionization (LDI)-promoting surfaces for high-throughput identification of peptides. The driving force of our work was to design a new material composed of a conventional MALDI matrix covalently attached to silica with a high organic/inorganic ratio in order to improve the UV absorption by such LDI hybrid matrices. Amorphous CHCA-functionalized silica presenting an organic content up to 1.3 mmol g(-1) (around 40% in weight from TGA and elementary analysis measurements) gave very interesting LDI performances in terms of detection sensitivity as well as relative ionization discrepancy (spectral suppression) through the analyses of small synthetic peptide mixtures (550-1300 Da) taking CHCA and amorphous silica as model matrices for control experiments.

  4. Manganese oxide nanoparticle-assisted laser desorption/ionization mass spectrometry for medical applications

    Directory of Open Access Journals (Sweden)

    Shu Taira, Kenji Kitajima, Hikaru Katayanagi, Eiichiro Ichiishi and Yuko Ichiyanagi

    2009-01-01

    Full Text Available We prepared and characterized manganese oxide magnetic nanoparticles (d =5.6 nm and developed nanoparticle-assited laser desorption/ionization (nano-PALDI mass spectrometry. The nanoparticles had MnO2 and Mn2O3 cores conjugated with hydroxyl and amino groups, and showed paramagnetism at room temperature. The nanoparticles worked as an ionization assisting reagent in mass spectroscopy. The mass spectra showed no background in the low m/z. The nanoparticles could ionize samples of peptide, drug and proteins (approx. 5000 Da without using matrix, i.e., 2,5-dihydroxybenzoic acid (DHB, 4-hydroxy-α-cinnamic acid (CHCA and liquid matrix, as conventional ionization assisting reagents. Post source decay spectra by nano-PALDI mass spectrometry will yield information of the chemical structure of analytes.

  5. Surface-Assisted Laser Desorption Ionization of Low Molecular Organic Substances on Oxidized Porous Silicon

    Science.gov (United States)

    Shmigol, I. V.; Alekseev, S. A.; Lavrynenko, O. Yu.; Zaitsev, V. N.; Barbier, D.; Pokrovskiy, V. A.

    Desorption/ionization on silicon (DIOS) mass spectra of methylene blue (MB+Cl-) were studied using p+-type oxidized monofunctional porous silicon (PS-OX mono ) free layers. Reduction/protonation processes of methylene blue (MB) dye were investigated. It was shown that SiH x terminal sites on oxidized surface of porous silicon (PS-OX) are not the rate-determining factor for the reduction/protonation in DIOS. Tunneling of electron through the dielectric layer of nanostructures on silicon surface under effect of local electrostatic and electromagnetic fields is considered to be the most significant factor of adsorbate-adsorbent electron exchange and further laser-induced ion formation.

  6. Tissue imaging with a stigmatic mass microscope using laser desorption/ionization

    Science.gov (United States)

    Awazu, Kunio; Hazama, Hisanao; Hamanaka, Tomonori; Aoki, Jun; Toyoda, Michisato; Naito, Yasuhide

    2012-03-01

    A novel stigmatic mass microscope using laser desorption/ionization and a multi-turn time-of-flight mass spectrometer, MULTUM-IMG, has been developed. Stigmatic ion images of crystal violet masked by a fine square mesh grid with a 12.7 μm pitch were clearly observed, and the estimated spatial resolution was about 3 μm in the linear mode with a 20-fold ion optical magnification. Tissue sections of a brain and eyes of a mouse stained with crystal violet and methylene blue were observed in the linear mode, and the stigmatic total ion images of crystal violet and methylene blue agreed well with the optical photomicrograph of the same sections. Especially, the fine structure in the cornea tissue was clearly observed with a spatial resolution in the range of micrometers. Although the total measurement time of the stigmatic ion image for the whole-eye section was about 59 minutes using a laser with a 10 Hz repetition rate, the measurement time could be reduced to about 35 s using a laser with a 1 kHz repetition rate and automation of measurements. The stigmatic mass microscope developed in this research should be suitable for high-spatial resolution and high-throughput imaging mass spectrometry for pathology, pharmacokinetics, and so on.

  7. Quantum dynamics of STM and laser induced desorption of atoms and molecules from surfaces

    CERN Document Server

    Boendgen, G

    2001-01-01

    The manipulation of atoms and molecules at solid surfaces by electronic excitations with electrons (or holes) emitted from the tip of a scanning tunneling microscope (STM) or with laser radiation is both of applied and fundamental interest, e.g. for micro- and nanostructuring of materials, the clarification of elementary (catalytic) reaction mechanisms and for the question of how to treat the quantum dynamics of a laser or STM driven 'system' (the adsorbate) in contact with a dissipative (energy-withdrawing) 'bath' (the substrate). Desorption induced by electronic transitions (DIET) and its variant DIMET (M = multiple) are among the simplest possible 'reactions' of adsorbate-surface systems; usually involving extremely short-lived electronically excited intermediates. In this thesis, the ultra-short dynamics of directly (localised to the adsorbate-substrate complex) and indirectly (i.e., through the substrate) stimulated DIET and DIMET processes was studied for Si(100)-(2x1):H(D) and Pt(111):NO. Isotope effec...

  8. Identification of organic pigments in automotive coatings using laser desorption mass spectrometry.

    Science.gov (United States)

    Stachura, Sylwia; Desiderio, Vincent J; Allison, John

    2007-05-01

    When one looks at an automotive coating, one sees color due to pigments. Modern organic pigments, with high molar absorptivities, may be only minor components of the mixture. Laser desorption mass spectrometry (LDMS) has been shown to be a useful tool for the analysis of colorants such as pen ink dyes. Here, LDMS is used to determine its utility for the identification of pigments, in simple media and in more complex paints. Small paint chips can be introduced into the LDMS instrument, and when an ultraviolet laser is focused on a portion of a chip, ions representative of the pigment(s) are selectively formed. Some pigments such as quinacridones and copper phthalocyanine are very stable and are desorbed and ionized intact. In contrast, benzimidazolones, which contain some single-skeletal bonds, form fragment ions. This method proves to be sensitive and convenient, as no sample preparation is required. The presence of inorganic pigments in addition to modern organic pigments can be determined, and pigments can be directly identified in actual automotive paint chip samples.

  9. Tandem Mass Spectrometry on a Miniaturized Laser Desorption Time-of-Flight Mass Spectrometer

    Science.gov (United States)

    Li, Xiang; Cornish, Timothy; Getty, Stephanie A.; Brinckerhoff, William B.

    2016-01-01

    Tandem mass spectrometry (MSMS) is a powerful and widely-used technique for identifying the molecular structure of organic constituents of a complex sample. Application of MSMS to the study of unknown planetary samples on a remote space mission would contribute to our understanding of the origin, evolution, and distribution of extraterrestrial organics in our solar system. Here we report on the realization of MSMS on a miniaturized laser desorption time-of-flight mass spectrometer (LD-TOF-MS), which is one of the most promising instrument types for future planetary missions. This achievement relies on two critical components: a curved-field reflectron and a pulsed-pin ion gate. These enable use of the complementary post-source decay (PSD) and laser-assisted collision induced dissociation (L-CID) MSMS methods on diverse measurement targets with only modest investment in instrument resources such as volume and weight. MSMS spectra of selected molecular targets in various organic standards exhibit excellent agreement when compared with results from a commercial, laboratory-scale TOF instrument, demonstrating the potential of this powerful technique in space and planetary environments.

  10. Electroless plating of silver nanoparticles on porous silicon for laser desorption/ionization mass spectrometry

    Science.gov (United States)

    Yan, Hong; Xu, Ning; Huang, Wen-Yi; Han, Huan-Mei; Xiao, Shou-Jun

    2009-03-01

    An improved DIOS (desorption ionization on porous silicon) method for laser desorption/ionization mass spectrometry (LDI MS) by electroless plating of silver nanoparticles (AgNPs) on porous silicon (PSi) was developed. By addition of 4-aminothiophenol (4-ATP) into the AgNO3 plating solution, the plating speed can be slowed down and simultaneously 4-ATP self-assembled monolayers (SAMs) on AgNPs (4-ATP/AgNPs) were formed. Both AgNPs and 4-ATP/AgNPs coated PSi substrates present much higher stability, sensitivity and reproducibility for LDI MS than the un-treated porous silicon ones. Their shelf life in air was tested for several weeks to a month and their mass spectra still displayed the same high quality and sensitivity as the freshly prepared ones. And more 4-ATP SAMs partly play a role of matrix to increase the ionization efficiency. A small organic molecule of tetrapyridinporphyrin (TPyP), oligomers of polyethylene glycol (PEG 400 and 2300), and a peptide of oxytocin were used as examples to demonstrate the feasibility of the silver-plated PSi as a matrix-free-like method for LDI MS. This approach can obtain limits of detection to femtomoles for TPyP, subpicomoles for oxytocin, and picomoles for PEG 400 and 2300, comparable to the traditional matrix method and much better than the DIOS method. It simplifies the sample preparation as a matrix-free-like method without addition of matrix molecules and homogenizes the sample spread over the spot for better and more even mass signals.

  11. Calibration of matrix-assisted laser desorption/ionization time-of-flight peptide mass fingerprinting spectra

    DEFF Research Database (Denmark)

    Hjernø, Karin; Højrup, Peter

    2007-01-01

    This chapter describes a number of aspects important for calibration of matrix-assisted laser desorption/ionization time-of-flight spectra prior to peptide mass fingerprinting searches. Both multipoint internal calibration and mass defect-based calibration is illustrated. The chapter describes how...... potential internal calibrants, like tryptic autodigest peptides and keratin-related peptides, can be identified and used for high-precision calibration. Furthermore, the construction of project/user-specific lists of potential calibrants is illustrated....

  12. Calibration of matrix-assisted laser desorption/ionization time-of-flight peptide mass fingerprinting spectra

    DEFF Research Database (Denmark)

    Hjernø, Karin; Højrup, Peter

    2007-01-01

    This chapter describes a number of aspects important for calibration of matrix-assisted laser desorption/ionization time-of-flight spectra prior to peptide mass fingerprinting searches. Both multipoint internal calibration and mass defect-based calibration is illustrated. The chapter describes ho...... potential internal calibrants, like tryptic autodigest peptides and keratin-related peptides, can be identified and used for high-precision calibration. Furthermore, the construction of project/user-specific lists of potential calibrants is illustrated....

  13. ADVANCED APPLICATIONS OF MATRIX ASSISTED LASER DESORPTION IONIZATION – TIME OF FLIGHT (MALDI-TOF) MASS SPECTROMETRY IN FOOD LIPIDOMICS

    OpenAIRE

    Picariello, Gianluca

    2013-01-01

    The application of matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) to the study of lipids has been long underestimated due to a series of intrinsic limitations associated to the technique, including the interference of matrix ion signals in the low m/z region, the natural tendency of lipids to fragment even under the “soft” ionization conditions of MALDI, the scarce reproducibility of the analysis, the inability in discriminating positional regioi...

  14. Nanoparticle-assisted laser desorption/ionization mass spectrometry: Novel sample preparation methods and nanoparticle screening for plant metabolite imaging

    Energy Technology Data Exchange (ETDEWEB)

    Yagnik, Gargey B. [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    The main goal of the presented research is development of nanoparticle based matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). This dissertation includes the application of previously developed data acquisition methods, development of novel sample preparation methods, application and comparison of novel nanoparticle matrices, and comparison of two nanoparticle matrix application methods for MALDI-MS and MALDI-MS imaging.

  15. Matrix-assisted laser desorption/ionization matrices for negative mode metabolomics.

    Science.gov (United States)

    Fagerer, Stephan R; Nielsen, Simone; Ibáñez, Alfredo; Zenobi, Renato

    2013-01-01

    Matrix-assisted laser desorption/ionization (MALDI) has been shown to be highly sensitive for analyzing low-mass compounds such as metabolites if the right matrix is used. 9-aminoacridine (9AA) is the most commonly employed matrix for negative mode MALDI-MS in metabolomics. However, matrix interferences and the strongly varying sensitivity for different metabolites make a search for alternative matrices desirable, in order to identify compounds with a different chemical background and/or favoring a different range of analytes. We tested the performance of a series of potential negative mode MALDI matrices with a mix of 29 metabolites containing amino acids, nucleotide phosphates and Krebs cycle intermediates. While ethacridine lactate was found to provide limits of detection (LODs) in the low femtomole range for nucleotide phosphates, amino acids and Krebs cycle intermediates in the low picomole range, 4-amino-2-methylquinoline showed LODs in the picomole range for most metabolites, but is capable of ionizing a broader range of analytes than both 9AA and ethacridine.

  16. Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

    Science.gov (United States)

    Bibi, Aisha; Ju, Huangxian

    2016-04-01

    A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Rapid drug detection in oral samples by porous silicon assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Lowe, Rachel D; Guild, Georgia E; Harpas, Peter; Kirkbride, Paul; Hoffmann, Peter; Voelcker, Nicolas H; Kobus, Hilton

    2009-11-01

    The demand for analysis of oral fluid for illicit drugs has arisen with the increased adoption of roadside testing, particularly in countries where changes in legislation allow random roadside testing of drivers for the presence of a palette of illicit drugs such as methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA) and Delta9-tetrahydrocannabinol (THC). Oral samples are currently tested for such drugs at the roadside using an immunoassay-based commercial test kit. Positive roadside tests are sent for confirmatory laboratory analysis, traditionally by means of gas chromatography/mass spectrometry (GC/MS). We present here an alternative rapid analysis technique, porous silicon assisted laser desorption/ionization time-of-flight mass spectrometry (pSi LDI-MS), for the high-throughput analysis of oral fluids. This technique alleviates the need for sample derivatization, requires only sub-microliter sample volumes and allows fast analysis (of the order of seconds). In this study, the application of the technique is demonstrated with real samples from actual roadside testing. The analysis of oral samples resulted in detection of MA and MDMA with no extraction and analysis of THC after ethyl acetate extraction. We propose that, subject to miniaturization of a suitable mass spectrometer, this technique is well suited to underpin the deployment of oral fluid testing in the clinic, workplace and on the roadside. Copyright 2009 John Wiley & Sons, Ltd.

  18. Design and Characterization of a High-power Laser-induced Acoustic Desorption (LIAD) Probe Coupled with a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer

    OpenAIRE

    Shea, Ryan C.; Habicht, Steven C.; Vaughn, Weldon E.; Kenttämaa, Hilkka I.

    2007-01-01

    We report here the construction and characterization of a high-power laser-induced acoustic desorption (LIAD) probe designed for Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometers to facilitate analysis of non-volatile, thermally labile compounds. This “next generation” LIAD probe offers significant improvements in sensitivity and desorption efficiency for analytes with larger molecular weights via the use of higher laser irradiances. Unlike the previous probes which utiliz...

  19. Developments and Applications of Electrophoresis and Small Molecule Laser Desorption Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hui [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Ultra-sensitive native fluorescence detection of proteins with miniaturized one- and two-dimensional polyacrylamide gel electrophoresis was achieved with laser side-entry excitation, which provides both high excitation power and low background level. The detection limit for R-phycoerythrin protein spots in 1-D SDS-PAGE was as low as 15 fg, which corresponds to 40 thousand molecules only. The average detection limit of six standard native proteins was 5 pg per band and the dynamic range spanned more than 3 orders of magnitude. Approximately 150 protein spots from 30 ng of total Escherichia coli extraction were detected on a 0.8 cm x 1 cm gel in two-dimensional separation. Estrogen-DNA adducts as 4-OHE1(E2)-1-N3Ade and 4-OHEI(E2)-2-NacCys were hypothesized as early risk assessment of prostate and breast cancers. Capillary electrophoresis, luminescence/absorption spectroscopy and LC-MS were used to characterize and detect these adducts. Monoclonal antibodies against each individual adduct were developed and used to enrich such compounds from urine samples of prostate and breast cancer patients as well as healthy people. Adduct 4-OHE1-1-N3Ade was detected at much higher level in urine from subjects with prostate cancer patients compared to healthy males. The same adduct and 4-OHEI-2-NacCys were also detected at a much higher level in urine from a woman with breast carcinoma than samples from healthy controls. These two DNA adducts may serve as novel biomarkers for early diagnostic of cancers. The adsorption properties of R-phycoerythrin (RPE), on the fused-silica surface were studied using capillary electrophoresis (CE) and single molecule spectroscopy. The band shapes and migration times were measured in CE. Adsorption and desorption events were recorded at the single-molecule level by imaging of the evanescent-field layer using total internal reflection. The adsorbed RPE molecules on the fused-silica prism surface were

  20. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  1. A laser desorption-electron impact ionization ion trap mass spectrometer for real-time analysis of single atmospheric particles

    Science.gov (United States)

    Simpson, E. A.; Campuzano-Jost, P.; Hanna, S. J.; Robb, D. B.; Hepburn, J. H.; Blades, M. W.; Bertram, A. K.

    2009-04-01

    A novel aerosol ion trap mass spectrometer combining pulsed IR laser desorption with electron impact (EI) ionization for single particle studies is described. The strengths of this instrument include a two-step desorption and ionization process to minimize matrix effects; electron impact ionization, a universal and well-characterized ionization technique; vaporization and ionization inside the ion trap to improve sensitivity; and an ion trap mass spectrometer for MSn experiments. The instrument has been used for mass spectral identification of laboratory generated pure aerosols in the 600 nm-1.1 [mu]m geometric diameter range of a variety of aromatic and aliphatic compounds, as well as for tandem mass spectrometry studies (up to MS3) of single caffeine particles. We investigate the effect of various operational parameters on the mass spectrum and fragmentation patterns. The single particle detection limit of the instrument was found to be a 325 nm geometric diameter particle (8.7 × 107 molecules or 22 fg) for 2,4-dihydroxybenzoic acid. Lower single particle detection limits are predicted to be attainable by modifying the EI pulse. The use of laser desorption-electron impact (LD-EI) in an ion trap is a promising technique for determining the size and chemical composition of single aerosol particles in real time.

  2. Depth profiling of inks in authentic and counterfeit banknotes by electrospray laser desorption ionization/mass spectrometry.

    Science.gov (United States)

    Kao, Yi-Ying; Cheng, Sy-Chyi; Cheng, Chu-Nian; Shiea, Jentaie

    2016-01-01

    Electrospray laser desorption ionization is an ambient ionization technique that generates neutrals via laser desorption and ionizes those neutrals in an electrospray plume and was utilized to characterize inks in different layers of copy paper and banknotes of various currencies. Depth profiling of inks was performed on overlapping color bands on copy paper by repeatedly scanning the line with a pulsed laser beam operated at a fixed energy. The molecules in the ink on a banknote were desorbed by irradiating the banknote surface with a laser beam operated at different energies, with results indicating that different ions were detected at different depths. The analysis of authentic $US100, $100 RMB and $1000 NTD banknotes indicated that ions detected in 'color-shifting' and 'typography' regions were significantly different. Additionally, the abundances of some ions dramatically changed with the depth of the aforementioned regions. This approach was used to distinguish authentic $1000 NTD banknotes from counterfeits. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Desorption of H atoms from graphite (0001) using XUV free electron laser pulses

    DEFF Research Database (Denmark)

    Siemer, B.; Olsen, Thomas; Hoger, T.

    2010-01-01

    The desorption of neutral H atoms from graphite with femtosecond XUV pulses is reported. The velocity distribution of the atoms peaks at extremely low kinetic energies. A DFT-based electron scattering calculation traces this distribution to desorption out of specific adsorption sites on graphite......, and identifies the highest vibrational state in the adsorbate potential as a major source for the slow atoms. It is evident that multiple electron scattering processes are required for this desorption. A direct electronic excitation of a repulsive hydrogen-carbon bond seems not to be important....

  4. A laser desorption ionization/matrix-assisted laser desorption ionization target system applicable for three distinct types of instruments (LinTOF/curved field RTOF, LinTOF/RTOF and QqRTOF) with different performance characteristics from three vendors.

    Science.gov (United States)

    Rados, Edita; Pittenauer, Ernst; Frank, Johannes; Varmuza, Kurt; Allmaier, Günter

    2018-04-30

    We have developed a target system which enables the use of only one target (i.e. target preparation set) for three different laser desorption ionization (LDI)/matrix-assisted laser desorption ionization (MALDI) mass spectrometric instruments. The focus was on analysing small biomolecules with LDI for future use of the system for the study of meteorite samples (carbonaceous chondrites) using devices with different mass spectrometric performance characteristics. Three compounds were selected due to their potential presence in meteoritic chondrites: tryptophan, 2-deoxy-d-ribose and triphenylene. They were prepared (with and without MALDI matrix, i.e. MALDI and LDI) and analysed with three different mass spectrometers (LinTOF/curved field RTOF, LinTOF/RTOF and QqRTOF). The ion sources of two of the instruments were run at high vacuum, and one at intermediate pressure. Two devices used a laser wavelength of 355 nm and one a wavelength of 337 nm. The developed target system operated smoothly with all devices. Tryptophan, 2-deoxy-d-ribose and triphenylene showed similar desorption/ionization behaviour for all instruments using the LDI mode. Interestingly, protonated tryptophan could be observed only with the LinTOF/curved field RTOF device in LDI and MALDI mode, while sodiated molecules were observed with all three instruments (in both ion modes). Deprotonated tryptophan was almost completely obscured by matrix ions in the MALDI mode whereas LDI yielded abundant deprotonated molecules. The presented target system allowed successful analyses of the three compounds using instruments from different vendors with only one preparation showing different analyser performance characteristics. The elemental composition with the QqRTOF analyser and the high-energy 20 keV collision-induced dissociation fragmentation will be important in identifying unknown compounds in chondrites. © 2018 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd.

  5. The Characterization of Laser Ablation Patterns and a New Definition of Resolution in Matrix Assisted Laser Desorption Ionization Imaging Mass Spectrometry (MALDI-IMS)

    Science.gov (United States)

    O'Rourke, Matthew B.; Raymond, Benjamin B. A.; Padula, Matthew P.

    2017-05-01

    Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) is a technique that has seen a sharp rise in both use and development. Despite this rapid adoption, there have been few thorough investigations into the actual physical mechanisms that underlie the acquisition of IMS images. We therefore set out to characterize the effect of IMS laser ablation patterns on the surface of a sample. We also concluded that the governing factors that control spatial resolution have not been correctly defined and therefore propose a new definition of resolution.

  6. A Compact, Solid-State UV (266 nm) Laser System Capable of Burst-Mode Operation for Laser Ablation Desorption Processing

    Science.gov (United States)

    Arevalo, Ricardo, Jr.; Coyle, Barry; Paulios, Demetrios; Stysley, Paul; Feng, Steve; Getty, Stephanie; Binkerhoff, William

    2015-01-01

    Compared to wet chemistry and pyrolysis techniques, in situ laser-based methods of chemical analysis provide an ideal way to characterize precious planetary materials without requiring extensive sample processing. In particular, laser desorption and ablation techniques allow for rapid, reproducible and robust data acquisition over a wide mass range, plus: Quantitative, spatially-resolved measurements of elemental and molecular (organic and inorganic) abundances; Low analytical blanks and limits-of-detection ( ng g-1); and, the destruction of minimal quantities of sample ( g) compared to traditional solution and/or pyrolysis analyses (mg).

  7. Direct analysis of samples by mass spectrometry: From elements to bio-molecules using laser ablation inductively couple plasma mass spectrometry and laser desorption/ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Perdian, David C. [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Mass spectrometric methods that are able to analyze solid samples or biological materials with little or no sample preparation are invaluable to science as well as society. Fundamental research that has discovered experimental and instrumental parameters that inhibit fractionation effects that occur during the quantification of elemental species in solid samples by laser ablation inductively coupled plasma mass spectrometry is described. Research that determines the effectiveness of novel laser desorption/ionization mass spectrometric methods for the molecular analysis of biological tissues at atmospheric pressure and at high spatial resolution is also described. A spatial resolution is achieved that is able to analyze samples at the single cell level.

  8. A new approach for detection of explosives based on ion mobility spectrometry and laser desorption/ionization on porous silicon

    Science.gov (United States)

    Kuzishchin, Yury; Kotkovskii, Gennadii; Martynov, Igor; Dovzhenko, Dmitriy; Chistyakov, Alexander

    2016-05-01

    We demonstrate a new way for detection ultralow concentration of explosives in this study. It combines an ion mobility spectrometry (IMS) and a promising method of laser desorption/ionization on silicon (DIOS). The DIOS is widely used in mass spectrometry due to the possibility of small molecule detection and high sensitivity. It is known that IMS based on laser ion source is a power method for the fast detection of ultralow concentration of organic molecules. However requirement of using high energy pulse ultraviolet laser increases weight and size of the device. The use of DIOS in an ion source of IMS could decrease energy pulse requirements and allows one to construct both compact and high sensitive device for analyzing gas and liquid probes. On the other hand mechanisms of DIOS in gas media is poorly studied, especially in case of nitroaromatic compounds. The investigation of the desorption/ionization on porous silicon (pSi) surface of nitroaromatic compounds has been carried out for 2,4,6-trinitrotoluene (TNT) using IMS and mass spectrometry (MS). It has been demonstrated that TNT ion formation in a gas medium is a complicated process and includes both an electron emission from the pSi surface with subsequent ion-molecular reactions in a gas phase and a proton transfer between pSi surface and TNT molecule.

  9. Detection and mapping of Cannabinoids in single hair samples through rapid derivatization- Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

    OpenAIRE

    Beasley, Emma; Francese, Simona; Bassindale, Thomas

    2016-01-01

    The sample preparation method reported in this work has permitted for the first time the application of Matrix Assisted Laser Desorption Ionization Mass Spectrometry Profiling and Imaging (MALDI-MSP and MALDI-MSI) for the detection and mapping of cannabinoids in a single hair sample. MALDI-MSI analysis of hair samples has recently been suggested as an alternative technique to traditional methods of GC-MS and LC-MS due to simpler sample preparation, the ability to detect a narrower time frame ...

  10. Phosphopeptide detection and sequencing by matrix-assisted laser desorption/ionization quadrupole time-of-flight tandem mass spectrometry

    DEFF Research Database (Denmark)

    Bennett, Keiryn L; Stensballe, Allan; Podtelejnikov, Alexandre V

    2002-01-01

    A prototype matrix-assisted laser desorption/ionization quadrupole time-of-flight (MALDI-TOF) tandem mass spectrometer was used to sequence a series of phosphotyrosine-, phosphothreonine- and phosphoserine-containing peptides. The high mass resolution and mass accuracy of the instrument allowed...... ion at m/z 216.04 was observed in these MALDI low-energy CID tandem mass spectra. Elimination of phosphate groups was evident from the triphosphorylated peptide but not from the monophosphorylated species. The main fragmentation pathway for the synthetic phosphothreonine-containing peptide...

  11. Pigments and proteins in green bacterial chlorosomes studied by matrix-assisted laser desorption ionization mass spectrometry

    DEFF Research Database (Denmark)

    Persson, S; Sönksen, C P; Frigaard, N-U

    2000-01-01

    We have used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for mass determination of pigments and proteins in chlorosomes, the light-harvesting organelles from the photosynthetic green sulfur bacterium Chlorobium tepidum. By applying a small volume (1...... homologs in a small amount of green bacterial cells. In addition to information on pigments, the MALDI spectra also contained peaks from chlorosome proteins. Thus we have been able with high precision to confirm the molecular masses of the chlorosome proteins CsmA and CsmE which have been previously...

  12. Fusobacterium nucleatum subspecies identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Nie, Shuping; Tian, Baoyu; Wang, Xiaowei; Pincus, David H; Welker, Martin; Gilhuley, Kathleen; Lu, Xuedong; Han, Yiping W; Tang, Yi-Wei

    2015-04-01

    We explored the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of Fusobacterium nucleatum subspecies. MALDI-TOF MS spectra of five F. nucleatum subspecies (animalis, fusiforme, nucleatum, polymorphum, and vincentii) were analyzed and divided into four distinct clusters, including subsp. animalis, nucleatum, polymorphum, and fusiforme/vincentii. MALDI-TOF MS with the modified SARAMIS database further correctly identified 28 of 34 F. nucleatum clinical isolates to the subspecies level. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

    International Nuclear Information System (INIS)

    Huang, H; Shi, H; Chen, W; Yu, Y; Lin, D; Xu, Q; Feng, S; Lin, J; Huang, Z; Li, Y; Chen, R

    2013-01-01

    This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites. (letter)

  14. Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging

    Directory of Open Access Journals (Sweden)

    Millar A Harvey

    2011-07-01

    Full Text Available Abstract Matrix-Assisted Laser Desorption/Ionisation (MALDI mass spectrometry imaging (MSI uses the power of high mass resolution time of flight (ToF mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

  15. Rapid detection of undesired cosmetic ingredients by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Ouyang, Jie; An, Dongli; Chen, Tengteng; Lin, Zhiwei

    2017-10-01

    In recent years, cosmetic industry profits soared due to the widespread use of cosmetics, which resulted in illicit manufacturers and products of poor quality. Therefore, the rapid and accurate detection of the composition of cosmetics has become crucial. At present, numerous methods, such as gas chromatography and liquid chromatography-mass spectrometry, were available for the analysis of cosmetic ingredients. However, these methods present several limitations, such as failure to perform comprehensive and rapid analysis of the samples. Compared with other techniques, matrix-assisted laser desorption ionization time-of-flight mass spectrometry offered the advantages of wide detection range, fast speed and high accuracy. In this article, we briefly summarized how to select a suitable matrix and adjust the appropriate laser energy. We also discussed the rapid identification of undesired ingredients, focusing on antibiotics and hormones in cosmetics.

  16. Spatially resolved protein hydrogen exchange measured by matrix-assisted laser desorption ionization in-source decay

    DEFF Research Database (Denmark)

    Rand, Kasper D; Bache, Nicolai; Nedertoft, Morten M

    2011-01-01

    Mass spectrometry has become a powerful tool for measuring protein hydrogen exchange and thereby reveal the structural dynamics of proteins in solution. Here we describe the successful application of a matrix-assisted laser desorption ionization (MALDI) mass spectrometry approach based on in......-source decay (ISD) to measure spatially resolved amide backbone hydrogen exchange. By irradiating deuterated protein molecules in a crystalline matrix with a high laser fluence, they undergo prompt fragmentation. Spatially resolved deuteration levels are readily obtained by mass analysis of consecutive...... fragment ions. MALDI ISD analysis of deuterated cytochrome c yielded an extensive series of c-fragment ions which originate from cleavage of nearly all N-C(α) bonds (Cys17 to Glu104) allowing for a detailed analysis of the deuterium content of the backbone amides. While hydrogen scrambling can be major...

  17. Ion-to-Neutral Ratios and Thermal Proton Transfer in Matrix-Assisted Laser Desorption/Ionization

    Science.gov (United States)

    Lu, I.-Chung; Chu, Kuan Yu; Lin, Chih-Yuan; Wu, Shang-Yun; Dyakov, Yuri A.; Chen, Jien-Lian; Gray-Weale, Angus; Lee, Yuan-Tseh; Ni, Chi-Kung

    2015-07-01

    The ion-to-neutral ratios of four commonly used solid matrices, α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (2,5-DHB), sinapinic acid (SA), and ferulic acid (FA) in matrix-assisted laser desorption/ionization (MALDI) at 355 nm are reported. Ions are measured using a time-of-flight mass spectrometer combined with a time-sliced ion imaging detector. Neutrals are measured using a rotatable quadrupole mass spectrometer. The ion-to-neutral ratios of CHCA are three orders of magnitude larger than those of the other matrices at the same laser fluence. The ion-to-neutral ratios predicted using the thermal proton transfer model are similar to the experimental measurements, indicating that thermal proton transfer reactions play a major role in generating ions in ultraviolet-MALDI.

  18. Laser desorption/ionization mass spectrometry on nanostructured semiconductor substrates: DIOS(TM) and QuickMass(TM)

    Science.gov (United States)

    Law, K. P.

    2010-02-01

    In the era of systems biology, new analytical platforms are under demand. Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a promising high throughput laser mass spectrometry approach that has attracted a lot of attention, and has been commercialized. Another substrate material manufactured by physical method has also been made commercially available under the trade name of QuickMass(TM). These two commercial substrates, DIOS(TM) and QuickMass(TM), were investigated independently from the manufacturers and were characterized by a number of advanced surface techniques. This work determined (1) the correlation between the substrate physicochemical properties and their LDI activity, (2) the feasibility of metabolic profiling from complex biological matrices and (3) the laser desorption/ionization mechanism. The DIOS(TM) substrate was characterized with a thick nano-sized porous layer, a high surface concentration of fluorocarbon and silicon oxides and super-hydrophobicity. In contrast, the QuickMass(TM) substrate consisted of a non-porous germanium thin-film. The relatively high ionization efficiency obtained from the DIOS(TM) substrate was contributed to the fluorosilane manufacturing processes and its porous morphology. Despite the QuickMass(TM) substrate being less effective, it was noted that the use of germanium affords a self-cleaning mechanism and suppresses background interference of mass spectra. The suitability of DIOS(TM) substrates for metabolic profiling of complex biological matrices was demonstrated. DIOS mass spectra of human blood plasma, human urine and animal liver tissue extracts were produced. Suitable extraction methods were found to be important, but relatively simplified approaches were sufficient. Further investigations of the DIOS desorption/ionization mechanism were carried out. The previously proposed sub-surface state reaction could be a molten-solid interfacial state reaction of the substrate and this had a significant

  19. Detection of trace organics in Mars analog samples containing perchlorate by laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Li, Xiang; Danell, Ryan M; Brinckerhoff, William B; Pinnick, Veronica T; van Amerom, Friso; Arevalo, Ricardo D; Getty, Stephanie A; Mahaffy, Paul R; Steininger, Harald; Goesmann, Fred

    2015-02-01

    Evidence from recent Mars missions indicates the presence of perchlorate salts up to 1 wt % level in the near-surface materials. Mixed perchlorates and other oxychlorine species may complicate the detection of organic molecules in bulk martian samples when using pyrolysis techniques. To address this analytical challenge, we report here results of laboratory measurements with laser desorption mass spectrometry, including analyses performed on both commercial and Mars Organic Molecule Analyzer (MOMA) breadboard instruments. We demonstrate that the detection of nonvolatile organics in selected spiked mineral-matrix materials by laser desorption/ionization (LDI) mass spectrometry is not inhibited by the presence of up to 1 wt % perchlorate salt. The organics in the sample are not significantly degraded or combusted in the LDI process, and the parent molecular ion is retained in the mass spectrum. The LDI technique provides distinct potential benefits for the detection of organics in situ on the martian surface and has the potential to aid in the search for signs of life on Mars.

  20. An investigation of liquid secondary ion and laser desorption mass spectroscopy for the analysis of planar chromatograms

    Energy Technology Data Exchange (ETDEWEB)

    Dunphy, J.C.

    1990-11-01

    In the work described in this dissertation, interfaces between two mass spectrometric methods, liquid secondary ion mass spectrometry (LSIMS) and laser desorption/ionization Fourier transform mass spectrometry (LD/FTMS), and thin-layer chromatography (TLC) and slab gel electrophoresis were developed for bioanalytical applications. In an investigation of direct LSIMS for TLC analysis (TLC/LSIMS), mass spectra of bile acids and bile salts were characterized directly from high-performance TLC plates. The scanning ability of the LSIMS instrument was used to generate spatial profiles of the characteristic bile acid ions in the mass spectra. A procedure for the analysis of bile salts in dog bile was developed involving an extraction step, followed by TLC separation and direct TLC/LSIMS detection and semi-quantitation. For peptides, an experiment called selected-sequence monitoring'' was developed to locate target peptides related in structure in complex mixtures developed on TLC plates. Ions characteristic of the bradykinin and enkephalin peptides were used to generate spatial profiles of members of those peptide families on TLC plates. Using a Fourier transform mass spectrometer (FTMS), a fundamental investigation was conducted into the factors affecting the quality of analytical data obtained using direct laser desorption/ionization to produce mass spectra from TLC plates.

  1. Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Sangwon [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS protocols with various alternative assisting materials were developed and applied to many biological systems of interest. Colloidal graphite was used as a matrix for IMS of small molecules for the first time and methodologies for analyses of small metabolites in rat brain tissues, fruits, and plant tissues were developed. With rat brain tissues, the signal enhancement for cerebroside species by colloidal graphite was observed and images of cerebrosides were successfully generated by IMS. In addition, separation of isobaric lipid ions was performed by imaging tandem MS. Directly from Arabidopsis flowers, flavonoids were successfully profiled and heterogeneous distribution of flavonoids in petals was observed for the first time by graphite-assisted LDI(GALDI) IMS.

  2. The Effect of Collimating Lens Focusing on Laser Beam Shape in Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS)

    Science.gov (United States)

    O'Rourke, Matthew B.; Raymond, Benjamin B. A.; Djordjevic, Steven P.; Padula, Matthew P.

    2018-01-01

    Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time.

  3. The Effect of Collimating Lens Focusing on Laser Beam Shape in Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS)

    Science.gov (United States)

    O'Rourke, Matthew B.; Raymond, Benjamin B. A.; Djordjevic, Steven P.; Padula, Matthew P.

    2018-03-01

    Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time.

  4. Design and performance of a matrix-assisted laser desorption time-of-flight mass spectrometer utilizing a pulsed nitrogen laser

    International Nuclear Information System (INIS)

    Brown, R.S.; Gilfrich, N.L.

    1991-01-01

    The design considerations and experimental performance of a linear time-of-flight mass spectrometer are reported for performing matrix-assisted laser desorption studies. A simple pulsed gas-discharge nitrogen laser (337.1 nm) is successfully used in contrast to the more widely used frequency-quadrupled (266 nm) or frequency-tripled (355 nm) Nd:YAG solid-state laser. Optical considerations in utilizing the pulsed nitrogen laser are discussed and a simple optical arrangement is described which allows for suitable imaging of the poor spatial beam profile of the pulsed nitrogen laser. Laser spot sizes of 150x450 μm are obtainable. As with the frequency-tripled Nd:YAG laser, sinapic acid is found to be the most useful matrix for producing protonated molecular species from proteins. Appropriate laser power levels are determined, as matrix/sample levels. Adequate response for most small to medium molecular weight proteins is obtained for less than 1 pmol of sample. A simple einsel lens incorporated into the ion source does not appear to provide any significant focusing on the laser-desorbed ions; however, a constant d.c. voltage applied to beam stirring plates enhances the ion signal significantly. Selective, pulsed deflection of the low-mass ions produced from the matrix is also utilized to prevent excessive saturation of the microchannel plate ion detector. High source potentials are found to provide improved resolution and sensitivity in comparison with lower source potentials combined with post-acceleration at the detector. Representative mass spectra of several proteins and peptides are presented. Increased formation of photoinduced adduct ions are observed in comparison with that reported for matrix-assisted laser desorption experiments utilizing a Nd:YAG laser and significant amounts of dimer and trimer ions are produced. Significantly more peak broadening than would normally be expected is observed above 20000 u. This may be due to the post-acceleration design of

  5. Electronically driven adsorbate excitation mechanism in femtosecond-pulse laser desorption

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Hedegård, Per; Heinz, T. F.

    1995-01-01

    a systematic theoretical treatment of this coupling process in the language of an electronic friction, which generates Langevin noise in the adsorbate center-of-mass degrees of freedom, while the electronic degrees of freedom are at a high temperature. Starting from an influence-functional path......-integral description, a simple formula for the electronic friction is defined which is valid at all electronic temperatures. At low temperatures the formalism makes contact with the electronic friction appearing in the theory of adsorbate vibrational damping, whereas at high temperatures comparable with the adsorbate...... electronic excitation energies the friction becomes strongly temperature dependent due to dominance by virtual excitations between different adsorbate potential energy surfaces. The former regime is related to the electronic friction model for the desorption process, and the latter to the desorption induced...

  6. Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer

    International Nuclear Information System (INIS)

    Zhong Hongying; Fu Jieying; Wang Xiaoli; Zheng Shi

    2012-01-01

    Highlights: ► Irradiation of photons with energies more than the band gap generates electron–hole pairs. ► Electron tunneling probability is dependent on the electron mobility. ► Tunneling electrons are captured by charge deficient atoms. ► Unpaired electrons induce cleavages of chemical bonds. - Abstract: Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ = 355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO 2 nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry.

  7. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 2. Surface-Enhanced Raman Spectroscopy - Recent Advancement of Raman Spectroscopy. Ujjal Kumar Sur. General Article Volume 15 Issue 2 February 2010 pp 154-164 ...

  8. Some characteristics of matrix-assisted UV laser desorption/ionization mass spectrometric analysis of large proteins

    Science.gov (United States)

    Perera, I. K.; Kantartzoglou, S.; Dyer, P. E.

    1996-12-01

    We have performed experiments to explore the characteristics of the matrix-assisted laser desorption/ionization (MALDI) process and to ascertain optimal operational conditions for observing intact molecular ions of large proteins. In this study, several methods have been adopted for the preparation of analyte samples. Of these, the samples prepared with the simple dried-droplet method were found to be the most suitable for the generation of the large molecular clusters, while the near-uniform spin-coated samples were observed to produce highly reproducible molecular ion signals of relatively high mass resolutions. A resulting mass spectrum which illustrates the formation of cluster ions up to the 26-mer [26M+H]+ of bovine insulin corresponding to a mass of about 150,000 Da, is presented. The effect of fluence on the extent of clustering of protein molecules has been studied, the results revealing the existence of an optimum fluence for detecting the large cluster ions. Investigations have also indicated that the use of polyethylene-coated metallic substrates as sample supports can considerably reduce the fragmentation of the matrix/analyte molecular ions and the desorption of "neat" MALDI matrices deposited on these polyethylene-coated sample probes enhance their aggregation, forming up to the heptamer [7M+H]+ of the matrix, ferulic acid. The dependence of the mass resolution on the applied acceleration voltage and the desorption fluence has been examined and the results obtained are discussed in terms of a simple analysis of the linear time-of-flight mass spectrometer. A spectrum of chicken egg lysozyme (M~14,306) displaying the high mass resolutions (M/[Delta]M~690) that can be attained when the mass spectrometer is operated in the reflectron mode is also presented.

  9. Detecting Biosignatures Associated with Minerals by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transorm Mass Spectromety (GALDI-FTMS)

    Energy Technology Data Exchange (ETDEWEB)

    C. Doc Richardson; J. Michelle Kotler; Nancy W. Hinman; Timothy R. McJunkin; Jill R. Scott

    2008-07-01

    The ability to detect carbon signatures that can be linked to complex, possibly biogenic, organic molecules is imperative in research into the origin and distribution of life in our solar system particularly when used in conjunction with inorganic, mineralogical, and isotopic signatures that provide strong evidence for geochemical influences of living organisms on their environment. Ideally, the method used to detect these signatures must (i) accurately and automatically translate the organic and other information into usable forms, (ii) precisely distinguish such information from alternative compositions, (iii) operate with high spatial resolution coupled with precise location abilities, and (iv) require little to no sample preparation because of the potential for contamination. Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform mass spectrometer (FTMS) has been used to determine the presence of bio/organic molecules (BOM) associated with different minerals and mineraloids including oxide, sulfate, carbonate, chloride, and silicate minerals. BOM is defined as an organic structure that can be produced by living organisms or derived from another organic compound made by living organisms (i.e., degradation product). GALDI requires no sample preparation because the mineral matrix assists desorption. Ultimately, however, the detectability of BOM is controlled by the desorption efficiency, ionization efficiency, and the specific experimental conditions. Results from experiments with combinations of known BOM and mineral standards indicated that the detectability of BOM increased with decreasing concentration, contrary to most analytical procedures. Results suggest that BOM when combined with certain minerals is more easily detected than when combined with other minerals. Such conclusions can guide selection of appropriate samples for sample return missions.

  10. Ionization in matrix-assisted laser desorption/ionization: singly charged molecular ions are the lucky survivors.

    Science.gov (United States)

    Karas, M; Glückmann, M; Schäfer, J

    2000-01-01

    A new model for the ionization processes in UV matrix-assisted laser desorption/ionization (MALDI) which accounts for the major phenomena observed is presented and discussed. The model retains elements of earlier approaches, such as photoionization and photochemical reactions, but it redefines these in the light of new working questions, most importantly why only singly charged ions are detected. Based on experimental evidence, the formation of singly and multiply charged clusters by a deficiency/excess of ions and also by photoionization and subsequent photochemical processes is pointed out to be the major ionization processes, which typically occur in parallel. The generation of electrons and their partial loss into the surrounding vacuum and solid, on the one hand, results in a positively charged ion-neutral plume facilitating a high overall ionization yield. On the other hand, these electrons, and also the large excess of protonated matrix ions in the negative ion mode, induce effective ion reneutralization in the plume. These neutralization processes are most effective for the highly charged cluster ions initially formed. Their fragmentation behaviour is evidenced in fast metastable fragmentation characteristics and agrees well with an electron capture dissociation mechanism and the enthalpy transfer upon neutralization forms the rationale for the prominent fragmentation and intense chemical noise accompanying successful MALDI. Within the course of the paper, cross-correlations with other desorption/ionization techniques and with earlier discussions on their mechanisms are drawn. Copyright 2000 John Wiley & Sons, Ltd.

  11. Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    David Rudd

    2015-03-01

    Full Text Available Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS methods namely nanostructure-assisted laser desorption ionisation (NALDI and desorption ionisation on porous silicon (DIOS surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples.

  12. Matrix-Assisted Laser Desorption Ionization Mass Spectrometry Imaging for Peptide and Protein Analyses: A Critical Review of On-Tissue Digestion

    NARCIS (Netherlands)

    Cillero-Pastor, B.; Heeren, R.M.A.

    2013-01-01

    Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has established itself among the plethora of mass spectrometry applications. In the biomedical field, MALDI-MSI is being more frequently recognized as a new method for the discovery of biomarkers and targets of

  13. Natural products in Glycyrrhiza glabra (licorice) rhizome imaged at the cellular level by atmospheric pressure matrix-assisted laser desorption/ionization tandem mass spectrometry imaging

    DEFF Research Database (Denmark)

    Li, Bin; Bhandari, Dhaka Ram; Janfelt, Christian

    2014-01-01

    The rhizome of Glycyrrhiza glabra (licorice) was analyzed by high-resolution mass spectrometry imaging and tandem mass spectrometry imaging. An atmospheric pressure matrix-assisted laser desorption/ionization imaging ion source was combined with an orbital trapping mass spectrometer in order...

  14. Differentiation of Clinically Relevant mucorales Rhizopus microsporus and R. arrhizus by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)

    NARCIS (Netherlands)

    Dolatabadi, S.; Kolecka, A.; Versteeg, Matthijs; de Hoog, Sybren G; Boekhout, Teun

    This study addresses the usefulness of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) for reliable identification of the two most frequently occuring clinical species of Rhizopus, namely R. arrhizus with its two varieties arrhizus and delemar and R.

  15. Identification of Fatty Acids, Phospholipids, and Their Oxidation Products Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry and Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Harmon, Christopher W.; Mang, Stephen A.; Greaves, John; Finlayson-Pitts, Barbara J.

    2010-01-01

    Electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have found increasing application in the analysis of biological samples. Using these techniques to solve problems in analytical chemistry should be an essential component of the training of undergraduate chemists. We…

  16. Identification of medically relevant species of arthroconidial yeasts by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry

    NARCIS (Netherlands)

    Kolecka, A.; Khayhan, K.; Groenewald, M.; Theelen, B.; Arabatzis, M.; Velegraki, A.; Kostrzewa, M.; Mares, M.; Taj-Aldeen, S.J.; Boekhout, T.

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar,

  17. Alkaloid profiling of the Chinese herbal medicine Fuzi by combination of matrix-assisted laser desorption ionization mass spectrometry with liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Wang, J.; Heijden, R. van der; Spijksma, G.; Reijmers, T.; Wang, M.; Xu, G.; Hankemeier, T.; Greef, J. van der

    2009-01-01

    A matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) method was developed for the high throughput and robust qualitative profiling of alkaloids in Fuzi-the processed lateral roots of the Chinese herbal medicine Aconitum carmichaeli Debx (A. carmichaeli). After optimization,

  18. Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment

    Science.gov (United States)

    Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

    2011-01-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

  19. Design and characterization of a high-power laser-induced acoustic desorption probe coupled with a fourier transform ion cyclotron resonance mass spectrometer.

    Science.gov (United States)

    Shea, Ryan C; Habicht, Steven C; Vaughn, Weldon E; Kenttämaa, Hilkka I

    2007-04-01

    We report here the construction and characterization of a high-power laser-induced acoustic desorption (LIAD) probe designed for Fourier transform ion cyclotron resonance mass spectrometers to facilitate analysis of nonvolatile, thermally labile compounds. This "next generation" LIAD probe offers significant improvements in sensitivity and desorption efficiency for analytes with larger molecular weights via the use of higher laser irradiances. Unlike the previous probes which utilized a power-limiting optical fiber to transmit the laser pulses through the probe, this probe employs a set of mirrors and a focusing lens. At the end of the probe, the energy from the laser pulses propagates through a thin metal foil as an acoustic wave, resulting in desorption of neutral molecules from the opposite side of the foil. Following desorption, the molecules can be ionized by electron impact or chemical ionization. Almost an order of magnitude greater power density (up to 5.0x10(9) W/cm2) is achievable on the backside of the foil with the high-power LIAD probe compared to the earlier LIAD probes (maximum power density approximately 9.0x10(8) W/cm2). The use of higher laser irradiances is demonstrated not to cause fragmentation of the analyte. The use of higher laser irradiances increases sensitivity since it results in the evaporation of a greater number of molecules per laser pulse. Measurement of the average velocities of LIAD-evaporated molecules demonstrates that higher laser irradiances do not correlate with higher velocities of the gaseous analyte molecules.

  20. Design and Characterization of a High-power Laser-induced Acoustic Desorption (LIAD) Probe Coupled with a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer

    Science.gov (United States)

    Shea, Ryan C.; Habicht, Steven C.; Vaughn, Weldon E.; Kenttämaa, Hilkka I.

    2008-01-01

    We report here the construction and characterization of a high-power laser-induced acoustic desorption (LIAD) probe designed for Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometers to facilitate analysis of non-volatile, thermally labile compounds. This “next generation” LIAD probe offers significant improvements in sensitivity and desorption efficiency for analytes with larger molecular weights via the use of higher laser irradiances. Unlike the previous probes which utilized a power limiting optical fiber to transmit the laser pulses through the probe, this probe employs a set of mirrors and a focusing lens. At the end of the probe, the energy from the laser pulses propagates through a thin metal foil as an acoustic wave, resulting in desorption of neutral molecules from the opposite side of the foil. Following desorption, the molecules can be ionized by electron impact or chemical ionization. Almost an order of magnitude greater power density (up to 5.0 × 109 W/cm2) is achievable on the backside of the foil with the high-power LIAD probe compared to the earlier LIAD probes (maximum power density ~9.0 × 108 W/cm2). The use of higher laser irradiances is demonstrated not to cause fragmentation of the analyte. The use of higher laser irradiances increases sensitivity since it results in the evaporation of a greater number of molecules per laser pulse. Measurement of the average velocities of LIAD evaporated molecules demonstrates that higher laser irradiances do not correlate with higher velocities of the gaseous analyte molecules. PMID:17319645

  1. Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry for the Investigation of Proteins and Peptides

    Science.gov (United States)

    Burnum, Kristin E.; Frappier, Sara L.; Caprioli, Richard M.

    2008-07-01

    Mass spectrometry (MS) is an excellent technology for molecular imaging because of its high data dimensionality. MS can monitor thousands of individual molecular data channels measured as mass-to-charge (m/z). We describe the use of matrix-assisted laser desorption/ionization (MALDI) MS for the image analysis of proteins, peptides, lipids, drugs, and metabolites in tissues. We discuss the basic instrumentation and sample preparation methods needed to produce high-resolution images and high image reproducibility. Matrix-addition protocols are briefly discussed along with normal operating procedures, and selected biological and medical applications of MALDI imaging MS are described. We give examples of both two- and three-dimensional imaging, including normal mouse embryo implantation, sperm maturation in mouse epididymis, protein distributions in brain sections, protein alterations as a result of drug administration, and protein changes in brain due to neurodegeneration and tumor formation. Advantages of this technology and future challenges for its improvement are discussed.

  2. Identification of Haemophilus influenzae and Haemophilus haemolyticus by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Bruin, J P; Kostrzewa, M; van der Ende, A; Badoux, P; Jansen, R; Boers, S A; Diederen, B M W

    2014-02-01

    Generally accepted laboratory methods that have been used for decades do not reliably distinguish between H. influenzae and H. haemolyticus isolates. H. haemolyticus strains are often incorrectly identified as nontypeable Haemophilus influenzae (NTHi). To distinguish H. influenzae from H. haemolyticus we have created a new database on the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) bio-typer 2 and compared the results with routine determination of Haemophilus (growth requirement for X and V factor), and multilocus sequence typing (MLST). In total we have tested 277 isolates, 244 H. influenzae and 33 H. haemolyticus. Using MLST as the gold standard, the agreement of MALDI-TOF MS was 99.6 %. MALDI-TOF MS allows reliable and rapid discrimination between H. influenzae and H. haemolyticus.

  3. Structural characterization of phospholipids by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    Marto, J A; White, F M; Seldomridge, S; Marshall, A G

    1995-11-01

    Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode.

  4. Laser desorption/ionization mass spectrometry of dye-sensitized solar cells: identification of the dye-electrolyte interaction.

    Science.gov (United States)

    Ellis, Hanna; Leandri, Valentina; Hagfeldt, Anders; Boschloo, Gerrit; Bergquist, Jonas; Shevchenko, Denys

    2015-05-01

    Dye-sensitized solar cells (DSCs) have great potential to provide sustainable electricity from sunlight. The photoanode in DSCs consists of a dye-sensitized metal oxide film deposited on a conductive substrate. This configuration makes the photoanode a perfect sample for laser desorption/ionization mass spectrometry (LDI-MS). We applied LDI-MS for the study of molecular interactions between a dye and electrolyte on the surface of a TiO2 photoanode. We found that a dye containing polyoxyethylene groups forms complexes with alkali metal cations from the electrolyte, while a dye substituted with alkoxy groups does not. Guanidinium ion forms adducts with neither of the two dyes. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Testing anionic spacers by SERRS (surface-enhanced resonance Raman scattering) of a cationic free-base porphyrin in systems with laser-ablated Ag colloids

    Czech Academy of Sciences Publication Activity Database

    Šmejkal, P.; Vlčková, B.; Procházka, M.; Mojzeš, P.; Pfleger, Jiří

    1999-01-01

    Roč. 19, č. 2 (1999), s. 243-247 ISSN 0924-2031 R&D Projects: GA ČR GA203/97/0259; GA ČR GA202/98/P139; GA AV ČR KSK4050111 Grant - others:GA UK(XC) 219/96/B/CH Institutional research plan: CEZ:AV0Z4050913 Keywords : laser ablation * porphyrin * SERRS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.848, year: 1999

  6. Ultrafast Desorption by Impulsive Vibrational Excitation (DIVE). Applications in laser surgery, mass spectrometry and towards ultimate limits in biodiagnosis

    International Nuclear Information System (INIS)

    Ren, Ling

    2015-07-01

    The prospects for minimally invasive surgery, spatial imaging with mass spectrometry and rapid high throughput biodiagnosis require new means of tissue incision and biomolecule extraction with conserved molecular structure. Towards this aim, a laser ablation process is utilized in this dissertation, which is capable of performing precise tissue incision with minimal collateral damage and extracting intact biological entities with conserved biological functions. The method is based on the recently developed Picosecond Infrared Laser (PIRL) designed to excite selectively the water vibrational modes under the condition of ultrafast Desorption by Impulsive Vibrational Excitation (DIVE). The basic concept is that the selectively excited water molecules act as propellant to ablate whole biological complexes into the plume, faster than any thermal deleterious effect or fragmentation that would mask molecular identities.The PIRL ablation under DIVE condition is applied for the first time to six types of ocular tissues, rendering precise and minimally invasive incisions in a well-controlled and reproducible way. An eminent demonstration is the contact-free and applanation-free corneal trephination with the PIRL. Mass spectrometry and other analytical techniques show that great abundance of proteins with various molecular weights are extracted from the tissue by the PIRL ablation, and that fragmentation or other chemical alternation does not occur to the proteins in the ablation plume. With various microscope imaging and biochemical analysis methods, nano-scale single protein molecules, viruses and cells in the ablation plume are found to be morphologically and functionally identical to their corresponding controls. The PIRL ablation provides a new means to push the frontiers of laser surgery in ophthalmology and can be applied to resolve chemical activities in situ and in vivo. The most important finding is the conserved nature of the extracted biological entities

  7. IN-SITU PROBING OF RADIATION-INDUCED PROCESSING OF ORGANICS IN ASTROPHYSICAL ICE ANALOGS-NOVEL LASER DESORPTION LASER IONIZATION TIME-OF-FLIGHT MASS SPECTROSCOPIC STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Gudipati, Murthy S.; Yang Rui, E-mail: gudipati@jpl.nasa.gov, E-mail: ryang73@ustc.edu [University of Maryland (United States)

    2012-09-01

    Understanding the evolution of organic molecules in ice grains in the interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons and ions is critical to our understanding of the connection between ISM and solar systems. Our study is aimed at reaching this goal of looking directly into radiation-induced processing in these ice grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar to matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe molecules embedded in water-ice at 5 K show for the first time that hydrogenation and oxygenation are the primary chemical reactions that occur in astrophysical ice analogs when subjected to Ly{alpha} radiation. We found that hydrogenation can occur over several unsaturated bonds and the product distribution corresponds to their stabilities. Multiple hydrogenation efficiency is found to be higher at higher temperatures (100 K) compared to 5 K-close to the interstellar ice temperatures. Hydroxylation is shown to have similar efficiencies at 5 K or 100 K, indicating that addition of O atoms or OH radicals to pre-ionized PAHs is a barrierless process. These studies-the first glimpses into interstellar ice chemistry through analog studies-show that once accreted onto ice grains PAHs lose their PAH spectroscopic signatures through radiation chemistry, which could be one of the reason for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks.

  8. IN-SITU PROBING OF RADIATION-INDUCED PROCESSING OF ORGANICS IN ASTROPHYSICAL ICE ANALOGS—NOVEL LASER DESORPTION LASER IONIZATION TIME-OF-FLIGHT MASS SPECTROSCOPIC STUDIES

    International Nuclear Information System (INIS)

    Gudipati, Murthy S.; Yang Rui

    2012-01-01

    Understanding the evolution of organic molecules in ice grains in the interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons and ions is critical to our understanding of the connection between ISM and solar systems. Our study is aimed at reaching this goal of looking directly into radiation-induced processing in these ice grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar to matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe molecules embedded in water-ice at 5 K show for the first time that hydrogenation and oxygenation are the primary chemical reactions that occur in astrophysical ice analogs when subjected to Lyα radiation. We found that hydrogenation can occur over several unsaturated bonds and the product distribution corresponds to their stabilities. Multiple hydrogenation efficiency is found to be higher at higher temperatures (100 K) compared to 5 K—close to the interstellar ice temperatures. Hydroxylation is shown to have similar efficiencies at 5 K or 100 K, indicating that addition of O atoms or OH radicals to pre-ionized PAHs is a barrierless process. These studies—the first glimpses into interstellar ice chemistry through analog studies—show that once accreted onto ice grains PAHs lose their PAH spectroscopic signatures through radiation chemistry, which could be one of the reason for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks.

  9. Femtosecond Laser Desorption of Thin Polymer Films from a Dielectric Surface

    Directory of Open Access Journals (Sweden)

    Mercadier L.

    2013-11-01

    Full Text Available We desorb polymer films from fused silica with a femtosecond laser and characterize the results by atomic force microscopy. Our study as a function of beam geometry and energy reveals two ways of achieving spatially controlled nanodesorption.

  10. Single-Particle Time-of-Flight Mass Spectrometry Utilizing a Femtosecond Desorption and Ionization Laser.

    Science.gov (United States)

    Zawadowicz, Maria A; Abdelmonem, Ahmed; Mohr, Claudia; Saathoff, Harald; Froyd, Karl D; Murphy, Daniel M; Leisner, Thomas; Cziczo, Daniel J

    2015-12-15

    Single-particle time-of-flight mass spectrometry has now been used since the 1990s to determine particle-to-particle variability and internal mixing state. Instruments commonly use 193 nm excimer or 266 nm frequency-quadrupled Nd:YAG lasers to ablate and ionize particles in a single step. We describe the use of a femtosecond laser system (800 nm wavelength, 100 fs pulse duration) in combination with an existing single-particle time-of-flight mass spectrometer. The goal of this project was to determine the suitability of a femtosecond laser for single-particle studies via direct comparison to the excimer laser (193 nm wavelength, ∼10 ns pulse duration) usually used with the instrument. Laser power, frequency, and polarization were varied to determine the effect on mass spectra. Atmospherically relevant materials that are often used in laboratory studies, ammonium nitrate and sodium chloride, were used for the aerosol. Detection of trace amounts of a heavy metal, lead, in an ammonium nitrate matrix was also investigated. The femtosecond ionization had a large air background not present with the 193 nm excimer and produced more multiply charged ions. Overall, we find that femtosecond laser ablation and ionization of aerosol particles is not radically different than that provided by a 193 nm excimer.

  11. Molecular dynamics investigation of desorption and ion separation following picosecond infrared laser (PIRL) ablation of an ionic aqueous protein solution

    Science.gov (United States)

    Zou, J.; Wu, C.; Robertson, W. D.; Zhigilei, L. V.; Miller, R. J. D.

    2016-11-01

    Molecular dynamics simulations were performed to characterize the ablation process induced by a picosecond infrared laser (PIRL) operating in the regime of desorption by impulsive vibrational excitation (DIVE) of a model peptide (lysozyme)/counter-ion system in aqueous solution. The simulations were performed for ablation under typical experimental conditions found within a time-of-flight mass spectrometer (TOF-MS), that is in vacuum with an applied electric field (E = ± 107 V/m), for up to 2 ns post-ablation and compared to the standard PIRL-DIVE ablation condition (E = 0 V/m). Further, a simulation of ablation under an extreme field condition (E = 1010 V/m) was performed for comparison to extend the effective dynamic range of the effect of the field on charge separation. The results show that the plume dynamics were retained under a typical TOF-MS condition within the first 1 ns of ablation. Efficient desorption was observed with more than 90% of water molecules interacting with lysozyme stripped off within 1 ns post-ablation. The processes of ablation and desolvation of analytes were shown to be independent of the applied electric field and thus decoupled from the ion separation process. Unlike under the extreme field conditions, the electric field inside a typical TOF-MS was shown to modify the ions' motion over a longer time and in a soft manner with no enhancement to fragmentation observed as compared to the standard PIRL-DIVE. The study indicates that the PIRL-DIVE ablation mechanism could be used as a new, intrinsically versatile, and highly sensitive ion source for quantitative mass spectrometry.

  12. Tailored nanopost arrays (NAPA) for laser desorption ionization in mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Walker, Bennett N.; Stolee, Jessica A.; Retterer, Scott T.

    2016-11-08

    The production and use of semiconducting nanopost arrays made by nanofabrication is described herein. These nanopost arrays (NAPA) provide improved laser ionization yields and controllable fragmentation with switching or modulation capabilities for mass spectrometric detection and identification of samples deposited on them.

  13. Basic poly(propylene glycols) as reference compounds for internal mass calibration in positive-ion matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Gross, Jürgen H

    2017-12-01

    Basic poly(propylene glycols), commercially available under the trade name Jeffamine, are evaluated for their potential use as internal mass calibrants in matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry. Due to their basic amino endgroups Jeffamines are expected to deliver [M+H] + ions in higher yields than neutral poly(propylene glycols) or poly(ethylene glycols). Aiming at accurate mass measurements and molecular formula determinations by matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry, four Jeffamines (M-600, M-2005, D-400, D-230) were thus compared. As a result, Jeffamine M-2005 is introduced as a new mass calibrant for positive-ion matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry in the range of m/z 200-1200 and the reference mass list is provided. While Jeffamine M-2005 is compatible with α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, and 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile matrix, its use in combination with 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile provides best results due to low laser fluence requirements. Applications to PEG 300, PEG 600, the ionic liquid trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)-trifluorophosphate, and [60]fullerene demonstrate mass accuracies of 2-5 ppm.

  14. Two-Step Resonance-Enhanced Desorption Laser Mass Spectrometry for In Situ Analysis of Organic-Rich Environments

    Science.gov (United States)

    Getty, S. A.; Grubisic, A.; Uckert, K.; Li, X.; Cornish, T.; Cook, J. E.; Brinckerhoff, W. B.

    2016-01-01

    A wide diversity of planetary surfaces in the solar system represent high priority targets for in situ compositional and contextual analysis as part of future missions. The planned mission portfolio will inform our knowledge of the chemistry at play on Mars, icy moons, comets, and primitive asteroids, which can lead to advances in our understanding of the interplay between inorganic and organic building blocks that led to the evolution of habitable environments on Earth and beyond. In many of these environments, the presence of water or aqueously altered mineralogy is an important indicator of habitable environments that are present or may have been present in the past. As a result, the search for complex organic chemistry that may imply the presence of a feedstock, if not an inventory of biosignatures, is naturally aligned with targeted analyses of water-rich surface materials. Here we describe the two-step laser mass spectrometry (L2MS) analytical technique that has seen broad application in the study of organics in meteoritic samples, now demonstrated to be compatible with an in situ investigation with technique improvements to target high priority planetary environments as part of a future scientific payload. An ultraviolet (UV) pulsed laser is used in previous and current embodiments of laser desorption/ionization mass spectrometry (LDMS) to produce ionized species traceable to the mineral and organic composition of a planetary surface sample. L2MS, an advanced technique in laser mass spectrometry, is selective to the aromatic organic fraction of a complex sample, which can provide additional sensitivity and confidence in the detection of specific compound structures. Use of a compact two-step laser mass spectrometer prototype has been previously reported to provide specificity to key aromatic species, such as PAHs, nucleobases, and certain amino acids. Recent improvements in this technique have focused on the interaction between the mineral matrix and the

  15. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry: protocol standardization and database expansion for rapid identification of clinically important molds.

    Science.gov (United States)

    Paul, Saikat; Singh, Pankaj; Rudramurthy, Shivaprakash M; Chakrabarti, Arunaloke; Ghosh, Anup K

    2017-12-01

    To standardize the matrix-assisted laser desorption ionization-time of flight mass spectrometry protocols and expansion of existing Bruker Biotyper database for mold identification. Four different sample preparation methods (protocol A, B, C and D) were evaluated. On analyzing each protein extraction method, reliable identification and best log scores were achieved through protocol D. The same protocol was used to identify 153 clinical isolates. Of these 153, 123 (80.3%) were accurately identified by using existing database and remaining 30 (19.7%) were not identified due to unavailability in database. On inclusion of missing main spectrum profile in existing database, all 153 isolates were identified. Matrix-assisted laser desorption ionization-time of flight mass spectrometry can be used for routine identification of clinically important molds.

  16. Identification of Wheat Varieties Using Matrix-assisted Laser Desorption/Ionisation Time-of-flight Mass Spectrometry and an Artificial Neural network

    DEFF Research Database (Denmark)

    Bloch, Helle Aagaard; Kesmir, Can; Petersen, Marianne Kjerstine

    1999-01-01

    A novel tool for variety identification of wheat (Triticum aestivum L,) has been developed: an artificial neural network (ANN) is used to classify the gliadin fraction analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The robustness of this no......A novel tool for variety identification of wheat (Triticum aestivum L,) has been developed: an artificial neural network (ANN) is used to classify the gliadin fraction analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The robustness...... of this novel method with respect to various experimental parameters has been tested, The results can be summarised: (i) With this approach 97% of the wheat varieties can be classified correctly with a corresponding correlation coefficient of 1.0, (ii) The method is fast since the time of extracting gliadins...

  17. Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for species identification of nonfermenting Gram-negative bacilli.

    Science.gov (United States)

    Almuzara, Marisa; Barberis, Claudia; Traglia, Germán; Famiglietti, Angela; Ramirez, Maria Soledad; Vay, Carlos

    2015-05-01

    Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) to identify 396 Nonfermenting Gram-Negative Bacilli clinical isolates was evaluated in comparison with conventional phenotypic tests and/or molecular methods. MALDI-TOF MS identified to species level 256 isolates and to genus or complex level 112 isolates. It identified 29 genera including uncommon species. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

    OpenAIRE

    Megumi Sakurai; Taro Sato; Jiawei Xu; Soichi Sato; Tatsuya Fujino

    2018-01-01

    Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe....

  19. Principles of hydrogen radical mediated peptide/protein fragmentation during matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Asakawa, Daiki

    2016-07-01

    Matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) is a very easy way to obtain large sequence tags and, thereby, reliable identification of peptides and proteins. Recently discovered new matrices have enhanced the MALDI-ISD yield and opened new research avenues. The use of reducing and oxidizing matrices for MALDI-ISD of peptides and proteins favors the production of fragmentation pathways involving "hydrogen-abundant" and "hydrogen-deficient" radical precursors, respectively. Since an oxidizing matrix provides information on peptide/protein sequences complementary to that obtained with a reducing matrix, MALDI-ISD employing both reducing and oxidizing matrices is a potentially useful strategy for de novo peptide sequencing. Moreover, a pseudo-MS(3) method provides sequence information about N- and C-terminus extremities in proteins and allows N- and C-terminal side fragments to be discriminated within the complex MALDI-ISD mass spectrum. The combination of high mass resolution of a Fourier transform-ion cyclotron resonance (FTICR) analyzer and the software suitable for MALDI-ISD facilitates the interpretation of MALDI-ISD mass spectra. A deeper understanding of the MALDI-ISD process is necessary to fully exploit this method. Thus, this review focuses first on the mechanisms underlying MALDI-ISD processes, followed by a discussion of MALDI-ISD applications in the field of proteomics. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:535-556, 2016. © 2014 Wiley Periodicals, Inc.

  20. Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging in the Study of Gastric Cancer: A Mini Review

    Directory of Open Access Journals (Sweden)

    Andrew Smith

    2017-12-01

    Full Text Available Gastric cancer (GC is one of the leading causes of cancer-related deaths worldwide and the disease outcome commonly depends upon the tumour stage at the time of diagnosis. However, this cancer can often be asymptomatic during the early stages and remain undetected until the later stages of tumour development, having a significant impact on patient prognosis. However, our comprehension of the mechanisms underlying the development of gastric malignancies is still lacking. For these reasons, the search for new diagnostic and prognostic markers for gastric cancer is an ongoing pursuit. Modern mass spectrometry imaging (MSI techniques, in particular matrix-assisted laser desorption/ionisation (MALDI, have emerged as a plausible tool in clinical pathology as a whole. More specifically, MALDI-MSI is being increasingly employed in the study of gastric cancer and has already elucidated some important disease checkpoints that may help us to better understand the molecular mechanisms underpinning this aggressive cancer. Here we report the state of the art of MALDI-MSI approaches, ranging from sample preparation to statistical analysis, and provide a complete review of the key findings that have been reported in the literature thus far.

  1. Metal-assisted polyatomic SIMS and laser desorption/ionization for enhanced small molecule imaging of bacterial biofilms.

    Science.gov (United States)

    Dunham, Sage J B; Comi, Troy J; Ko, Kyungwon; Li, Bin; Baig, Nameera F; Morales-Soto, Nydia; Shrout, Joshua D; Bohn, Paul W; Sweedler, Jonathan V

    2016-06-04

    Mass spectrometry imaging (MSI) has become an important analytical tool for many sectors of science and medicine. As the application of MSI expands into new areas of inquiry, existing methodologies must be adapted and improved to meet emerging challenges. Particularly salient is the need for small molecule imaging methods that are compatible with complex multicomponent systems, a challenge that is amplified by the effects of analyte migration and matrix interference. With a focus on microbial biofilms from the opportunistic pathogen Pseudomonas aeruginosa, the relative advantages of two established microprobe-based MSI techniques-polyatomic secondary ion mass spectrometry (SIMS) and laser desorption/ionization-are compared, with emphasis on exploring the effect of surface metallization on small molecule imaging. A combination of qualitative image comparison and multivariate statistical analysis demonstrates that sputtering microbial biofilms with a 2.5 nm layer of gold selectively enhances C60-SIMS ionization for several molecular classes including rhamnolipids and 2-alkyl-quinolones. Metallization also leads to the reduction of in-source fragmentation and subsequent ionization of media-specific background polymers, which improves spectral purity and image quality. These findings show that the influence of metallization upon ionization is strongly dependent on both the surface architecture and the analyte class, and further demonstrate that metal-assisted C60-SIMS is a viable method for small molecule imaging of intact molecular ions in complex biological systems.

  2. Matrix-assisted laser desorption/ionization mass spectrometric analysis of aliphatic biodegradable photoluminescent polymers using new ionic liquid matrices.

    Science.gov (United States)

    Serrano, Carlos A; Zhang, Yi; Yang, Jian; Schug, Kevin A

    2011-05-15

    In this study, two novel ionic liquid matrices (ILMs), N,N-diisopropylethylammonium 3-oxocoumarate and N,N-diisopropylethylammonium dihydroxymonooxoacetophenoate, were tested for the structural elucidation of recently developed aliphatic biodegradable polymers by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The polymers, formed by a condensation reaction of three components, citric acid, octane diol, and an amino acid, are fluorescent, but the exact mechanism behind their luminescent properties has not been fully elucidated. In the original studies, which introduced the polymer class (J. Yang et al., Proc. Natl. Acad. Sci. USA 2009, 106, 10086-10091), a hyper-conjugated cyclic structure was proposed as the source for the photoluminescent behavior. With the use of the two new ILMs, we present evidence that supports the presence of the proposed cyclization product. In addition, the new ILMs, when compared with a previously established ILM, N,N-diisopropylethylammonium α-cyano-3-hydroxycinnimate, provided similar signal intensities and maintained similar spectral profiles. This research also established that the new ILMs provided good spot-to-spot reproducibility and high ionization efficiency compared with corresponding crystalline matrix preparations. Many polymer features revealed through the use of the ILMs could not be observed with crystalline matrices. Ultimately, the new ILMs highlighted the composition of the synthetic polymers, as well as the loss of water that was expected for the formation of the proposed cyclic structure on the polymer backbone. Copyright © 2011 John Wiley & Sons, Ltd.

  3. Laser Desorption/Ionization Mass Spectrometric Imaging of Endogenous Lipids from Rat Brain Tissue Implanted with Silver Nanoparticles

    Science.gov (United States)

    Muller, Ludovic; Baldwin, Kathrine; Barbacci, Damon C.; Jackson, Shelley N.; Roux, Aurélie; Balaban, Carey D.; Brinson, Bruce E.; McCully, Michael I.; Lewis, Ernest K.; Schultz, J. Albert; Woods, Amina S.

    2017-08-01

    Mass spectrometry imaging (MSI) of tissue implanted with silver nanoparticulate (AgNP) matrix generates reproducible imaging of lipids in rodent models of disease and injury. Gas-phase production and acceleration of size-selected 8 nm AgNP is followed by controlled ion beam rastering and soft landing implantation of 500 eV AgNP into tissue. Focused 337 nm laser desorption produces high quality images for most lipid classes in rat brain tissue (in positive mode: galactoceramides, diacylglycerols, ceramides, phosphatidylcholines, cholesteryl ester, and cholesterol, and in negative ion mode: phosphatidylethanolamides, sulfatides, phosphatidylinositol, and sphingomyelins). Image reproducibility in serial sections of brain tissue is achieved within imaging of brain tissues spotted with pure standards was used to demonstrate that Ag cationized ceramide and diacylglycerol ions are from intact, endogenous species. In contrast, almost all Ag cationized fatty acid ions are a result of fragmentations of numerous lipid types having the fatty acid as a subunit. Almost no argentated intact fatty acid ions come from the pure fatty acid standard on tissue.

  4. Identification and localization of trauma-related biomarkers using matrix assisted laser desorption/ionization imaging mass spectrometry

    Science.gov (United States)

    Jones, Kirstin; Reilly, Matthew A.; Glickman, Randolph D.

    2017-02-01

    Current treatments for ocular and optic nerve trauma are largely ineffective and may have adverse side effects; therefore, new approaches are needed to understand trauma mechanisms. Identification of trauma-related biomarkers may yield insights into the molecular aspects of tissue trauma that can contribute to the development of better diagnostics and treatments. The conventional approach for protein biomarker measurement largely relies on immunoaffinity methods that typically can only be applied to analytes for which antibodies or other targeting means are available. Matrix assisted laser-assisted desorption/ionization imaging mass spectrometry (MALDI-IMS) is a specialized application of mass spectrometry that not only is well suited to the discovery of novel or unanticipated biomarkers, but also provides information about the spatial localization of biomarkers in tissue. We have been using MALDI-IMS to find traumarelated protein biomarkers in retina and optic nerve tissue from animal models subjected to ocular injury produced by either blast overpressure or mechanical torsion. Work to date by our group, using MALDI-IMS, found that the pattern of protein expression is modified in the injured ocular tissue as soon as 24 hr post-injury, compared to controls. Specific proteins may be up- or down-regulated by trauma, suggesting different tissue responses to a given injury. Ongoing work is directed at identifying the proteins affected and mapping their expression in the ocular tissue, anticipating that systematic analysis can be used to identify targets for prospective therapies for ocular trauma.

  5. Analysis of Microbial Mixtures by Matrix-assisted Laser Desorption/Ionization time-of-flight Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, Karen L.; Wunschel, Sharon C.; Jarman, Kristin H.; Valentine, Nancy B.; Petersen, Catherine E.; Kingsley, Mark T.; Zartolas, Kimberly A.; Saenz, Adam J.

    2002-12-15

    Many different laboratories are currently developing mass-spectrometric techniques to analyze and identify microorganisms. However, minimal work has been done with mixtures of bacteria. To demonstrate that microbial mixtures could be analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), mixed bacterial cultures were analyzed in a double-blind fashion. Nine different bacterial species currently in our MALDI-MS fingerprint library were used to generate 50 different simulated mixed bacterial cultures similar to that done for an initial blind study previously reported.(1) The samples were analyzed by MALDI-MS with automated data extraction and analysis algorithms developed in our laboratory. The components present in the sample were identified correctly to the species level in all but one of the samples. However, correctly eliminating closely related organisms was challenging for the current algorithms, especially in differentiating Serratia marcescens, Escherichia coli, and Yersinia enterocolitica, which have some similarities in their MALDI-MS fingerprints. Efforts to improve the specificity of the algorithms are in progress.

  6. Newborn screening by matrix-assisted laser desorption/ionization mass spectrometry based on parylene-matrix chip.

    Science.gov (United States)

    Kim, Jo-Il; Noh, Joo-Yoon; Kim, Mira; Park, Jong-Min; Song, Hyun-Woo; Kang, Min-Jung; Pyun, Jae-Chul

    2017-08-01

    Newborn screening for diagnosis of phenylketonuria, homocystinuria, and maple syrup urine disease have been conducted by analyzing the concentration of target amino acids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) based on parylene-matrix chip. Parylene-matrix chip was applied to MALDI-ToF MS analysis reducing the matrix peaks significantly at low mass-to-charge ratio range (m/z  0.98) and the LODs were ranging from 9.0 to 22.9 μg/mL. Effect of proteins in serum was estimated by comparing MALDI-ToF mass spectra of amino acids-spiked serum before and after the methanol extraction. Interference of other amino acids on analysis of target analyte was determined to be insignificant. From these results, MALDI-ToF MS based on parylene-matrix chip could be applicable to medical diagnosis of neonatal metabolic disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Novel ionic liquid matrices for qualitative and quantitative detection of carbohydrates by matrix assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Zhao, Xiaoyong; Shen, Shanshan; Wu, Datong; Cai, Pengfei; Pan, Yuanjiang

    2017-09-08

    Analysis of carbohydrates based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still challenging and researchers have been devoting themselves to efficient matrices discovery. In the present study, the design, synthesis, qualitative and quantitative performance of non-derivative ionic liquid matrices (ILMs) were reported. DHB/N-methylaniline (N-MA) and DHB/N-ethylaniline (N-EA), performing best for carbohydrate detection, have been screened out. The limit of detection for oligosaccharide provided by DHB/N-MA and DHB/N-EA were as low as 10 fmol. DHB/N-MA and DHB/N-EA showed significantly higher ion generation efficiency than DHB. The comparison of capacity to probe polysaccharide between these two ILMs and DHB also revealed their powerful potential. Their outstanding performance were probably due to lower proton affinities and stronger UV absorption at λ = 355 nm. What is more, taking DHB/N-MA as an example, quantitative analysis of fructo-oligosaccharide mixtures extracted and identified from rice noodles has been accomplished sensitively using an internal standard method. Overall, DHB/N-MA and DHB/N-EA exhibited excellent performance and might be significant sources as the carbohydrate matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Laser desorption/ionization time-of-flight mass spectrometry of triacylglycerols and other components in fingermark samples.

    Science.gov (United States)

    Emerson, Beth; Gidden, Jennifer; Lay, Jackson O; Durham, Bill

    2011-03-01

    The chemical composition of fingermarks could potentially be important for determining investigative leads, placing individuals at the time of a crime, and has applications as biomarkers of disease. Fingermark samples containing triacylglycerols (TAGs) and other components were analyzed using laser desorption/ionization (LDI) time-of-flight mass spectrometry (TOF MS). Only LDI appeared to be useful for this application while conventional matrix-assisted LDI-TOF MS was not. Tandem MS was used to identify/confirm selected TAGs. A limited gender comparison, based on a simple t-distribution and peaks intensities, indicated that two TAGs showed gender specificity at the 95% confidence level and two others at 97.5% confidence. Because gender-related TAGs differences were most often close to the standard deviation of the measurements, the majority of the TAGs showed no gender specificity. Thus, LDI-TOF MS is not a reliable indicator of gender based on fingermark analysis. Cosmetic ingredients present in some samples were identified. © 2011 American Academy of Forensic Sciences.

  9. Glycine identification in natural jarosites using laser desorption Fourier transform mass spectrometry: implications for the search for life on Mars.

    Science.gov (United States)

    Kotler, J Michelle; Hinman, Nancy W; Yan, Beizhan; Stoner, Daphne L; Scott, Jill R

    2008-04-01

    The jarosite group minerals have received increasing attention since the discovery of jarosite on the martian surface by the Mars Exploration Rover Opportunity. Given that jarosite can incorporate foreign ions within its structure, we have investigated the use of jarosite as an indicator of aqueous and biological processes on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide. One of the ions from the natural jarosites has been attributed to glycine because it was systematically observed in combinations of glycine with synthetic ammonium and potassium jarosites, Na(2)SO(4) and K(2)SO(4). The ability to observe these organic signatures in jarosite samples with an in situ instrumental technique, such as the one employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  10. Differentiation of Microbial Species and Strains in Coculture Biofilms by Multivariate Analysis of Laser Desorption Postionization Mass Spectra

    Energy Technology Data Exchange (ETDEWEB)

    University of Illinois at Chicago; Montana State University; Bhardwaj, Chhavi; Cui, Yang; Hofstetter, Theresa; Liu, Suet Yi; Bernstein, Hans C.; Carlson, Ross P.; Ahmed, Musahid; Hanley, Luke

    2013-04-01

    7.87 to 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze biofilms comprised of binary cultures of interacting microorganisms. The effect of photon energy was examined using both tunable synchrotron and laser sources of VUV radiation. Principal components analysis (PCA) was applied to the MS data to differentiate species in Escherichia coli-Saccharomyces cerevisiae coculture biofilms. PCA of LDPI-MS also differentiated individual E. coli strains in a biofilm comprised of two interacting gene deletion strains, even though these strains differed from the wild type K-12 strain by no more than four gene deletions each out of approximately 2000 genes. PCA treatment of 7.87 eV LDPI-MS data separated the E. coli strains into three distinct groups two ?pure? groups and a mixed region. Furthermore, the ?pure? regions of the E. coli cocultures showed greater variance by PCA when analyzed by 7.87 eV photon energies than by 10.5 eV radiation. Comparison of the 7.87 and 10.5 eV data is consistent with the expectation that the lower photon energy selects a subset of low ionization energy analytes while 10.5 eV is more inclusive, detecting a wider range of analytes. These two VUV photon energies therefore give different spreads via PCA and their respective use in LDPI-MS constitute an additional experimental parameter to differentiate strains and species.

  11. Probing of Metabolites in Finely Powdered Plant Material by Direct Laser Desorption Ionization Mass Spectrometry

    Science.gov (United States)

    Musharraf, Syed Ghulam; Ali, Arslan; Choudhary, M. Iqbal; Atta-ur-Rahman

    2014-04-01

    Natural products continue to serve as an important source of novel drugs since the beginning of human history. High-throughput techniques, such as MALDI-MS, can be techniques of choice for the rapid screening of natural products in plant materials. We present here a fast and reproducible matrix-free approach for the direct detection of UV active metabolites in plant materials without any prior sample preparation. The plant material is mechanically ground to a fine powder and then sieved through different mesh sizes. The collected plant material is dispersed using 1 μL solvent on a target plate is directly exposed to Nd:YAG 335 nm laser. The strategy was optimized for the analysis of plant metabolites after study of the different factors affecting the reproducibility and effectiveness of the analysis, including particle sizes effects, types of solvents used to disperse the sample, and the part of the plant analyzed. Moreover, several plant species, known for different classes of metabolites, were screened to establish the generality of the approach. The developed approach was validated by the characterization of withaferin A and nicotine in the leaves of Withania somnifera and Nicotiana tabacum, respectively, through comparison of its MS/MS data with the standard compound. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques were used for the tissue imaging purposes. This approach can be used to directly probe small molecules in plant materials as well as in herbal and pharmaceutical formulations for fingerprinting development.

  12. Negative Ion In-Source Decay Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Sequencing Acidic Peptides.

    Science.gov (United States)

    McMillen, Chelsea L; Wright, Patience M; Cassady, Carolyn J

    2016-05-01

    Matrix-assisted laser desorption/ionization (MALDI) in-source decay was studied in the negative ion mode on deprotonated peptides to determine its usefulness for obtaining extensive sequence information for acidic peptides. Eight biological acidic peptides, ranging in size from 11 to 33 residues, were studied by negative ion mode ISD (nISD). The matrices 2,5-dihydroxybenzoic acid, 2-aminobenzoic acid, 2-aminobenzamide, 1,5-diaminonaphthalene, 5-amino-1-naphthol, 3-aminoquinoline, and 9-aminoacridine were used with each peptide. Optimal fragmentation was produced with 1,5-diaminonphthalene (DAN), and extensive sequence informative fragmentation was observed for every peptide except hirudin(54-65). Cleavage at the N-Cα bond of the peptide backbone, producing c' and z' ions, was dominant for all peptides. Cleavage of the N-Cα bond N-terminal to proline residues was not observed. The formation of c and z ions is also found in electron transfer dissociation (ETD), electron capture dissociation (ECD), and positive ion mode ISD, which are considered to be radical-driven techniques. Oxidized insulin chain A, which has four highly acidic oxidized cysteine residues, had less extensive fragmentation. This peptide also exhibited the only charged localized fragmentation, with more pronounced product ion formation adjacent to the highly acidic residues. In addition, spectra were obtained by positive ion mode ISD for each protonated peptide; more sequence informative fragmentation was observed via nISD for all peptides. Three of the peptides studied had no product ion formation in ISD, but extensive sequence informative fragmentation was found in their nISD spectra. The results of this study indicate that nISD can be used to readily obtain sequence information for acidic peptides.

  13. Combined analysis of 1,3-benzodioxoles by crystalline sponge X-ray crystallography and laser desorption ionization mass spectrometry.

    Science.gov (United States)

    Hayashi, Yukako; Ohara, Kazuaki; Taki, Rika; Saeki, Tomomi; Yamaguchi, Kentaro

    2018-03-12

    The crystalline sponge (CS) method, which employs single-crystal X-ray diffraction to determine the structure of an analyte present as a liquid or an oil and having a low melting point, was used in combination with laser desorption ionization mass spectrometry (LDI-MS). 1,3-Benzodioxole derivatives were encapsulated in CS and their structures were determined by combining X-ray crystallography and MS. After the X-ray analysis, the CS was subjected to imaging mass spectrometry (IMS) with an LDI spiral-time-of-flight mass spectrometer (TOF-MS). The ion detection area matched the microscopic image of the encapsulated CS. In addition, the accumulated 1D mass spectra showed that fragmentation of the guest molecule (hereafter, guest) can be easily visualized without any interference from the fragment ions of CS except for two strong ion peaks derived from the tridentate ligand TPT (2,4,6-tris(4-pyridyl)-1,3,5-triazine) of the CS and its fragment. X-ray analysis clearly showed the presence of the guest as well as the π-π, CH-halogen, and CH-O interactions between the guest and the CS framework. However, some guests remained randomly diffused in the nanopores of CS. In addition, the detection limit was less than sub-pmol order based on the weight and density of CS determined by X-ray analysis. Spectroscopic data, such as UV-vis and NMR, also supported the encapsulation of the guest through the interaction between the guest and CS components. The results denote that the CS-LDI-MS method, which combines CS, X-ray analysis and LDI-MS, is effective for structure determination.

  14. Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

    Directory of Open Access Journals (Sweden)

    Anne Mayer-Scholl

    Full Text Available Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology.

  15. Direct Matrix-Assisted Laser Desorption-Ionisation (MALDI) Mass-Spectrometry Bacteria Profiling for Identifying and Characterizing Pathogens.

    Science.gov (United States)

    Ilina, E N

    2009-04-01

    This study examines the features and limitations of direct Matrix-Assisted Laser Desorption-Ionisation (MALDI) mass-spectrometry profiling of bacterial cells for investigating a microbial population. The optimal laboratory protocol, including crude bacteria lyses by a solution of 50% acetonitrile, 2.5% trifluoroacetic acid, and using α-cyano-4-hydroxy cinnamic acid as the MALDI matrix, has been developed. Two different bacteria species were under investigation, and representative mass spectra from 278 strains of Neisseria gonorrhoeae and 22 strains of Helicobacter pylori have been analyzed. It's known that both bacteria demonstrate a variable degree of polymorphism. For N. gonorrhoeae, the MALDI mass spectra that was collected possessed about 70 peaks, 20 of which were good reproducible ones. In spite of the fact that three peaks were found with differing spectra in some strains, little diversity in the N. gonorrhoeae population was revealed. This fact indicates the prospects in using direct MALDI mass-spectrometry profiling for gonococcus identification. In the case of H. pylori strains, the variety in the collected mass-spectra was shown to be essential. Only five peaks were present in more than 70% of strains, and a single mass value was common for all spectra. While these data call into question the possibility of the reliable species identification of H. pylori using this approach, the intraspecies differentiation of strains was offered. Good association between MALDI profile distributions and the region of strain isolation have been found. Thus, the suggested direct MALDI mass-spectrometry profiling strategy, coupled with special analysis software, seems promising for the species identification of N. gonorrhoeae but is assumed insufficient for H. pylori species determination. At the same time, this would create a very good chance for an epidemiological study of such variable bacteria as H. pylori.

  16. Differentiation of Streptococcus pneumoniae conjunctivitis outbreak isolates by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Williamson, Yulanda M; Moura, Hercules; Woolfitt, Adrian R; Pirkle, James L; Barr, John R; Carvalho, Maria Da Gloria; Ades, Edwin P; Carlone, George M; Sampson, Jacquelyn S

    2008-10-01

    Streptococcus pneumoniae (pneumococcus [Pnc]) is a causative agent of many infectious diseases, including pneumonia, septicemia, otitis media, and conjunctivitis. There have been documented conjunctivitis outbreaks in which nontypeable (NT), nonencapsulated Pnc has been identified as the etiological agent. The use of mass spectrometry to comparatively and differentially analyze protein and peptide profiles of whole-cell microorganisms remains somewhat uncharted. In this report, we discuss a comparative proteomic analysis between NT S. pneumoniae conjunctivitis outbreak strains (cPnc) and other known typeable or NT pneumococcal and streptococcal isolates (including Pnc TIGR4 and R6, Streptococcus oralis, Streptococcus mitis, Streptococcus pseudopneumoniae, and Streptococcus pyogenes) and nonstreptococcal isolates (including Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus) as controls. cPnc cells and controls were grown to mid-log phase, harvested, and subsequently treated with a 10% trifluoroacetic acid-sinapinic acid matrix mixture. Protein and peptide fragments of the whole-cell bacterial isolate-matrix combinations ranging in size from 2 to 14 kDa were evaluated by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Additionally Random Forest analytical tools and dendrogramic representations (Genesis) suggested similarities and clustered the isolates into distinct clonal groups, respectively. Also, a peak list of protein and peptide masses was obtained and compared to a known Pnc protein mass library, in which a peptide common and unique to cPnc isolates was tentatively identified. Information gained from this study will lead to the identification and validation of proteins that are commonly and exclusively expressed in cPnc strains which could potentially be used as a biomarker in the rapid diagnosis of pneumococcal conjunctivitis.

  17. Identification of Tsetse (Glossina spp. using matrix-assisted laser desorption/ionisation time of flight mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Antje Hoppenheit

    Full Text Available Glossina (G. spp. (Diptera: Glossinidae, known as tsetse flies, are vectors of African trypanosomes that cause sleeping sickness in humans and nagana in domestic livestock. Knowledge on tsetse distribution and accurate species identification help identify potential vector intervention sites. Morphological species identification of tsetse is challenging and sometimes not accurate. The matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS technique, already standardised for microbial identification, could become a standard method for tsetse fly diagnostics. Therefore, a unique spectra reference database was created for five lab-reared species of riverine-, savannah- and forest- type tsetse flies and incorporated with the commercial Biotyper 3.0 database. The standard formic acid/acetonitrile extraction of male and female whole insects and their body parts (head, thorax, abdomen, wings and legs was used to obtain the flies' proteins. The computed composite correlation index and cluster analysis revealed the suitability of any tsetse body part for a rapid taxonomical identification. Phyloproteomic analysis revealed that the peak patterns of G. brevipalpis differed greatly from the other tsetse. This outcome was comparable to previous theories that they might be considered as a sister group to other tsetse spp. Freshly extracted samples were found to be matched at the species level. However, sex differentiation proved to be less reliable. Similarly processed samples of the common house fly Musca domestica (Diptera: Muscidae; strain: Lei did not yield any match with the tsetse reference database. The inclusion of additional strains of morphologically defined wild caught flies of known origin and the availability of large-scale mass spectrometry data could facilitate rapid tsetse species identification in the future.

  18. Performance of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates.

    Science.gov (United States)

    Denis, Julie; Machouart, Marie; Morio, Florent; Sabou, Marcela; Kauffmann-LaCroix, Catherine; Contet-Audonneau, Nelly; Candolfi, Ermanno; Letscher-Bru, Valérie

    2017-01-01

    The genus Malassezia comprises commensal yeasts on human skin. These yeasts are involved in superficial infections but are also isolated in deeper infections, such as fungemia, particularly in certain at-risk patients, such as neonates or patients with parenteral nutrition catheters. Very little is known about Malassezia epidemiology and virulence. This is due mainly to the difficulty of distinguishing species. Currently, species identification is based on morphological and biochemical characteristics. Only molecular biology techniques identify species with certainty, but they are time-consuming and expensive. The aim of this study was to develop and evaluate a matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) database for identifying Malassezia species by mass spectrometry. Eighty-five Malassezia isolates from patients in three French university hospitals were investigated. Each strain was identified by internal transcribed spacer sequencing. Forty-five strains of the six species Malassezia furfur, M. sympodialis, M. slooffiae, M. globosa, M. restricta, and M. pachydermatis allowed the creation of a MALDI-TOF database. Forty other strains were used to test this database. All strains were identified by our Malassezia database with log scores of >2.0, according to the manufacturer's criteria. Repeatability and reproducibility tests showed a coefficient of variation of the log score values of Malassezia database allows easy, fast, and reliable identification of Malassezia species. Implementation of this database will contribute to a better, more rapid identification of Malassezia species and will be helpful in gaining a better understanding of their epidemiology. Copyright © 2016 Denis et al.

  19. Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates

    Science.gov (United States)

    Machouart, Marie; Morio, Florent; Sabou, Marcela; Kauffmann-LaCroix, Catherine; Contet-Audonneau, Nelly; Candolfi, Ermanno; Letscher-Bru, Valérie

    2016-01-01

    ABSTRACT The genus Malassezia comprises commensal yeasts on human skin. These yeasts are involved in superficial infections but are also isolated in deeper infections, such as fungemia, particularly in certain at-risk patients, such as neonates or patients with parenteral nutrition catheters. Very little is known about Malassezia epidemiology and virulence. This is due mainly to the difficulty of distinguishing species. Currently, species identification is based on morphological and biochemical characteristics. Only molecular biology techniques identify species with certainty, but they are time-consuming and expensive. The aim of this study was to develop and evaluate a matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) database for identifying Malassezia species by mass spectrometry. Eighty-five Malassezia isolates from patients in three French university hospitals were investigated. Each strain was identified by internal transcribed spacer sequencing. Forty-five strains of the six species Malassezia furfur, M. sympodialis, M. slooffiae, M. globosa, M. restricta, and M. pachydermatis allowed the creation of a MALDI-TOF database. Forty other strains were used to test this database. All strains were identified by our Malassezia database with log scores of >2.0, according to the manufacturer's criteria. Repeatability and reproducibility tests showed a coefficient of variation of the log score values of Malassezia database allows easy, fast, and reliable identification of Malassezia species. Implementation of this database will contribute to a better, more rapid identification of Malassezia species and will be helpful in gaining a better understanding of their epidemiology. PMID:27795342

  20. Identification of organic pigments in tattoo inks and permanent make-up using laser desorption ionisation mass spectrometry.

    Science.gov (United States)

    Niederer, Markus; Hauri, Urs; Kroll, Lydia; Hohl, Christopher

    2017-01-01

    Nowadays, about 12% of the European and 20% of the US population are tattooed. Rising concerns regarding consumer safety, led to legal restrictions on tattoo and permanent make-up (PMU) inks. Restrictions also include bans on certain colourants. Both ink types use organic pigments for colour-giving, plus inorganic pigments for white and black and colour tones. Pigments are only sparingly soluble in common solvents and occur as suspended particles in the ink matrix. Their detection and identification therefore pose a major challenge for laboratories involved in monitoring the legal compliance of tattoo inks and PMU. We overcame this challenge by developing a direct laser desorption ionisation time-of-flight mass spectrometry method, which included an easy sample clean up. The method proved to be capable of detecting and identifying organic pigments in almost all of the tested ink samples. Method validation and routine deployment during market surveys showed the method to be fit for purpose. Pigment screening of 396 tattoo inks and 55 PMU taken from the Swiss market between 2009 and 2017 lead to the following conclusions: Pigment variety is much greater in tattoo inks (18) than in PMU (10); four prohibited pigments (Pigment Green 7, Pigment Red 122, Pigment Violet 19 and 23) were found in both ink types; for PMU, these four pigments made up 12% of the pigment findings, compared to 32% for tattoo inks. Therefore, legal compliance of PMU was at a higher level. A comparison of pigments found with those declared on tattoo ink labels clearly showed that banned pigments are rarely declared, but rather masked by listing non present legal pigments and label forging; therefore, highlighting the urgency of widespread market controls.

  1. Rapid screening of mixed edible oils and gutter oils by matrix-assisted laser desorption/ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Tsz-Tsun; So, Pui-Kin; Zheng, Bo [Food Safety and Technology Research Centre, State Key Laboratory of Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom Kowloon, Hong Kong Special Administrative Region (China); Shenzhen Key Laboratory of Food Biological Safety Control and State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of The Hong Kong Polytechnic University, Shenzhen (China); Yao, Zhong-Ping, E-mail: zhongping.yao@polyu.edu.hk [Food Safety and Technology Research Centre, State Key Laboratory of Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom Kowloon, Hong Kong Special Administrative Region (China); Shenzhen Key Laboratory of Food Biological Safety Control and State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of The Hong Kong Polytechnic University, Shenzhen (China)

    2015-07-16

    Highlights: • Simplified sample preparation method for direct analysis of edible oils by MALDI-MS. • Establishment of a preliminary MALDI-MS spectral database of edible oils. • Rapid screening of mixed edible oils and gutter oils. - Abstract: Authentication of edible oils is a long-term issue in food safety, and becomes particularly important with the emergence and wide spread of gutter oils in recent years. Due to the very high analytical demand and diversity of gutter oils, a high throughput analytical method and a versatile strategy for authentication of mixed edible oils and gutter oils are highly desirable. In this study, an improved matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method has been developed for direct analysis of edible oils. This method involved on-target sample loading, automatic data acquisition and simple data processing. MALDI-MS spectra with high quality and high reproducibility have been obtained using this method, and a preliminary spectral database of edible oils has been set up. The authenticity of an edible oil sample can be determined by comparing its MALDI-MS spectrum and principal component analysis (PCA) results with those of its labeled oil in the database. This method is simple and the whole process only takes several minutes for analysis of one oil sample. We demonstrated that the method was sensitive to change in oil compositions and can be used for measuring compositions of mixed oils. The capability of the method for determining mislabeling enables it for rapid screening of gutter oils since fraudulent mislabeling is a common feature of gutter oils.

  2. Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Megumi Sakurai

    2018-03-01

    Full Text Available Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO as the matrix. Salicylic acid (Sal, glucuronic acid (Glu, ibuprofen (Ibu, and tyrosine (Tyr were ionized as deprotonated species (carboxylate anions by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe. Measurements of model peptides, angiotensin II (AngII and substance P (SubP, were also carried out but the obtained peak intensities were very low. In order to explain this result, the interaction between CdTe and AngII was confirmed by diffuse reflectance spectroscopy. The results suggest that electrostatic binding between semiconductor nanoparticles and AngII prevented the efficient desorption of AngII into the gas phase.

  3. Comparison of inert supports in laser desorption/ionization mass spectrometry of peptides: pencil lead, porous silica gel, DIOS-chip and NALDI target.

    Science.gov (United States)

    Shenar, Nawar; Cantel, Sonia; Martinez, Jean; Enjalbal, Christine

    2009-08-01

    In the search for alternative inert surfaces replacing silicon chips in Desorption/Ionization On porous Silicon (DIOS)-like mass spectrometry analyses, nanostructured silicon-based NALDI chips were evaluated in Laser Desorption/Ionization (LDI) of peptides. Comparisons were made using commercially available DIOS chips (MassPREP-DIOS-target), amorphous carbon powder from lead pencil and porous silica gel used for chromatographic purposes as reference supports. A set of synthetic model peptides presenting variable amino acid sequences of various lengths was analyzed under all conditions. The LDI responses of the four 'matrix-free' techniques were compared, especially in terms of peptide detection sensitivity and overall experiment robustness. Copyright (c) 2009 John Wiley & Sons, Ltd.

  4. Laser Desorption Ionization of As2Ch3 (Ch = S, Se, and Te) Chalcogenides Using Quadrupole Ion Trap Time-of-Flight Mass Spectrometry: A Comparative Study

    Science.gov (United States)

    Mawale, Ravi Madhukar; Ausekar, Mayuri Vilas; Prokeš, Lubomír; Nazabal, Virginie; Baudet, Emeline; Halenkovič, Tomáš; Bouška, Marek; Alberti, Milan; Němec, Petr; Havel, Josef

    2017-12-01

    Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As2Ch3 (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S p +/- and As m +/- ) and 34 binary (As m S p +/- ) species for As2S3 glass, 2 unary (Se q +/- ) and 26 binary (As m Se q +/- ) species for As2Se3 glass, 7 unary (Te r +/- ) and 23 binary (As m Te r +/- ) species for As2Te3 material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials. [Figure not available: see fulltext.

  5. Quantitation of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry using (18)O-labeled internal standards

    DEFF Research Database (Denmark)

    Mirgorodskaya, O A; Kozmin, Y P; Titov, M I

    2000-01-01

    for the tested sample by enzymatic hydrolysis of the same sample (with known concentration) in (18)O-water. A mathematical algorithm was developed which uses the isotopic patterns of the substance, the internal standard, and the substance/internal standard mixture for accurate quantitation of the substance......A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards...

  6. In situ liquid-liquid extraction as a sample preparation method for matrix-assisted laser desorption/ionization MS analysis of polypeptide mixtures

    DEFF Research Database (Denmark)

    Kjellström, Sven; Jensen, Ole Nørregaard

    2003-01-01

    A novel liquid-liquid extraction (LLE) procedure was investigated for preparation of peptide and protein samples for matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). LLE using ethyl acetate as the water-immiscible organic solvent enabled segregation of hydrophobic...... and hydrophilic polypeptides in mixtures, thereby reducing the complexity of mass spectra obtained by MALDI MS. The LLE technique was optimized for rapid and sensitive in situ (on-target) sample preparation for MALDI MS analysis of proteins and peptides at low-picomole and subpicomole levels. Addition of MALDI...

  7. Performance of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Aspergillus, Scedosporium, and Fusarium spp. in the Australian Clinical Setting.

    Science.gov (United States)

    Sleiman, Sue; Halliday, Catriona L; Chapman, Belinda; Brown, Mitchell; Nitschke, Joanne; Lau, Anna F; Chen, Sharon C-A

    2016-08-01

    We developed an Australian database for the identification of Aspergillus, Scedosporium, and Fusarium species (n = 28) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In a challenge against 117 isolates, species identification significantly improved when the in-house-built database was combined with the Bruker Filamentous Fungi Library compared with that for the Bruker library alone (Aspergillus, 93% versus 69%; Fusarium, 84% versus 42%; and Scedosporium, 94% versus 18%, respectively). Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  8. Species identification of clinical isolates of anaerobic bacteria: a comparison of two matrix-assisted laser desorption ionization-time of flight mass spectrometry systems

    DEFF Research Database (Denmark)

    Justesen, Ulrik Stenz; Holm, Anette; Knudsen, Elisa

    2011-01-01

    We compared two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems (Shimadzu/SARAMIS and Bruker) on a collection of consecutive clinically important anaerobic bacteria (n = 290). The Bruker system had more correct identifications to the species level...... (67.2% versus 49.0%), but also more incorrect identifications (7.9% versus 1.4%). The system databases need to be optimized to increase identification levels. However, MALDI-TOF MS in its present version seems to be a fast and inexpensive method for identification of most clinically important...

  9. Structure Determination of β-Glucans from Ganoderma lucidum with Matrix-assisted Laser Desorption/ionization (MALDI Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Wen-Bin Yang

    2008-08-01

    Full Text Available A novel method that uses matrix-assisted laser desorption/ionization (MALDI mass spectrometry to analyze molecular weight and sequencing of glucan in Ganoderma lucidum is presented. Thus, β-glucan, which was isolated from fruiting bodies of G. lucidum, was measured in a direct and fast way using MALDI mass spectrometry. In addition, tandem mass spectrometry of permethylated glucans of G. lucidum, dextran, curdlan and maltohexaose were also pursued and different fragment patterns were obtained. The G. lucidum glucan structure was determined and this method for linkage analysis of permethylated glucan has been proven feasible.

  10. Species determination of Culicoides biting midges via peptide profiling using matrix-assisted laser desorption ionization mass spectrometry.

    Science.gov (United States)

    Uhlmann, Katrin R; Gibb, Sebastian; Kalkhof, Stefan; Arroyo-Abad, Uriel; Schulz, Claudia; Hoffmann, Bernd; Stubbins, Francesca; Carpenter, Simon; Beer, Martin; von Bergen, Martin; Feltens, Ralph

    2014-08-24

    Culicoides biting midges are vectors of bluetongue and Schmallenberg viruses that inflict large-scale disease epidemics in ruminant livestock in Europe. Methods based on morphological characteristics and sequencing of genetic markers are most commonly employed to differentiate Culicoides to species level. Proteomic methods, however, are also increasingly being used as an alternative method of identification. These techniques have the potential to be rapid and may also offer advantages over DNA-based techniques. The aim of this proof-of-principle study was to develop a simple MALDI-MS based method to differentiate Culicoides from different species by peptide patterns with the additional option of identifying discriminating peptides. Proteins extracted from 7 Culicoides species were digested and resulting peptides purified. Peptide mass fingerprint (PMF) spectra were recorded using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and peak patterns analysed in R using the MALDIquant R package. Additionally, offline liquid chromatography (LC) MALDI-TOF tandem mass spectrometry (MS/MS) was applied to determine the identity of peptide peaks in one exemplary MALDI spectrum obtained using an unfractionated extract. We showed that the majority of Culicoides species yielded reproducible mass spectra with peak patterns that were suitable for classification. The dendrogram obtained by MS showed tentative similarities to a dendrogram generated from cytochrome oxidase I (COX1) sequences. Using offline LC-MALDI-TOF-MS/MS we determined the identity of 28 peptide peaks observed in one MALDI spectrum in a mass range from 1.1 to 3.1 kDa. All identified peptides were identical to other dipteran species and derived from one of five highly abundant proteins due to an absence of available Culicoides data. Shotgun mass mapping by MALDI-TOF-MS has been shown to be compatible with morphological and genetic identification of specimens. Furthermore

  11. Phenotypic identification of Porphyromonas gingivalis validated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Rams, Thomas E; Sautter, Jacqueline D; Getreu, Adam; van Winkelhoff, Arie J

    2016-05-01

    Porphyromonas gingivalis is a major bacterial pathogen in human periodontitis. This study used matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to assess the accuracy of a rapid phenotypic identification scheme for detection of cultivable P. gingivalis in human subgingival plaque biofilms. A total of 314 fresh cultivable subgingival isolates from 38 adults with chronic periodontitis were presumptively identified on anaerobically-incubated enriched Brucella blood agar primary isolation plates as P. gingivalis based on dark-pigmented colony morphology, lack of a brick-red autofluorescence reaction under long-wave ultraviolet light, and a positive CAAM fluorescence test for trypsin-like enzyme activity. Each presumptive P. gingivalis isolate, and a panel of other human subgingival bacterial species, were subjected to MALDI-TOF mass spectrometry analysis using a benchtop mass spectrometer equipped with software containing mass spectra for P. gingivalis in its reference library of bacterial protein profiles. A MALDI-TOF mass spectrometry log score of ≥1.7 was required for species identification of the subgingival isolates. All 314 (100%) presumptive P. gingivalis subgingival isolates were confirmed as P. gingivalis with MALDI-TOF mass spectrometry analysis (Cohen's kappa coefficient = 1.0). MALDI-TOF mass spectrometry log scores between 1.7 and 1.9, and ≥2.0, were found for 92 (29.3%) and 222 (70.7%), respectively, of the presumptive P. gingivalis clinical isolates. No other tested bacterial species was identified as P. gingivalis by MALDI-TOF mass spectrometry. Rapid phenotypic identification of cultivable P. gingivalis in human subgingival biofilm specimens was found to be 100% accurate with MALDI-TOF mass spectrometry. These findings provide validation for the continued use of P. gingivalis research data based on this species identification methodology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (GALDI-FTICR-MS)

    Energy Technology Data Exchange (ETDEWEB)

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; J. Michelle Kotler; Jill R. Scott

    2008-10-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) has been employed to determine how effectively bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO-2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition ofC18H39O7Na-. Anatural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination were estimated to be 3 parts per trillion or~7 zeptomoles (10-21) per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTICR-MS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  13. Contribution of thermal energy to initial ion production in matrix-assisted laser desorption/ionization observed with 2,4,6-trihydroxyacetophenone.

    Science.gov (United States)

    Lai, Yin-Hung; Chen, Bo-Gaun; Lee, Yuan Tseh; Wang, Yi-Sheng; Lin, Sheng Hsien

    2014-08-15

    Although several reaction models have been proposed in the literature to explain matrix-assisted laser desorption/ionization (MALDI), further study is still necessary to explore the important ionization pathways that occur under the high-temperature environment of MALDI. 2,4,6-Trihydroxyacetophenone (THAP) is an ideal compound for evaluating the contribution of thermal energy to an initial reaction with minimum side reactions. Desorbed neutral THAP and ions were measured using a crossed-molecular beam machine and commercial MALDI-TOF instrument, respectively. A quantitative model incorporating an Arrhenius-type desorption rate derived from transition state theory was proposed. Reaction enthalpy was calculated using GAUSSIAN 03 software with dielectric effect. Additional evidence of thermal-induced proton disproportionation was given by the indirect ionization of THAP embedded in excess fullerene molecules excited by a 450 nm laser. The quantitative model predicted that proton disproportionation of THAP would be achieved by thermal energy converted from a commonly used single UV laser photon. The dielectric effect reduced the reaction Gibbs free energy considerably even when the dielectric constant was reduced under high-temperature MALDI conditions. With minimum fitting parameters, observations of pure THAP and THAP mixed with fullerene both agreed with predictions. Proton disproportionation of solid THAP was energetically favorable with a single UV laser photon. The quantitative model revealed an important initial ionization pathway induced by the abrupt heating of matrix crystals. In the matrix crystals, the dielectric effect reduced reaction Gibbs free energy under typical MALDI conditions. The result suggested that thermal energy plays an important role in the initial ionization reaction of THAP. Copyright © 2014 John Wiley & Sons, Ltd.

  14. The effect of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry instrumentation parameters on the matrix-assisted laser desorption/ionization simulated size exclusion chromatography number-mass, average-weight and polydispersity values of dextran against corresponding values obtained by size exclusion chromatography.

    Science.gov (United States)

    Bashir, S; Giannakopulos, A E; Liu, J

    2017-12-01

    The matrix-assisted laser desorption/ionization simulated size exclusion chromatography (SECPC) average-number mass, weight average and polydispersity of dextran 1000 were determined by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry. The instrument parameters were varied and the SECPC value determined via the Bruker XMASS software was compared to the value obtained from aqueous-phase size exclusion chromatography. The aqueous-phase size exclusion chromatography values for average-number mass, weight average and polydispersity were 1223 Da, 1500 Da and 1.23 (1010 Da, 1270 Da and 1.26 from manufacturer), whereas the SECPC value varied on the instrumental parameters. The factors that had the greatest effect on the average-number mass, weight average and polydispersity were: (most effect on SECPC value) laser attenuation > matrix-analyte molar concentration > matrix-analyte molar ratios > delay extraction time > solvent-system composition > detector delay (least effect on SECPC value). The oligosaccharide signal distribution as a function of laser attenuation indicate that two distinct regions exist in dextran 1000, where one corresponds to the higher mass oligosaccharides (hexasaccharide or greater), while another region corresponds to lower oligosaccharides (tetra-saccharide). This distribution depends upon the crystallization of the biopolymer and the efficiency of desorption/ionization, which yields the SECPC value. There was broad agreement between the SECPC values and size exclusion chromatography values for dextran, although the polydispersity indicated by SECPC was less than size exclusion chromatography (1.10 vs. 1.26). It can be shown that for narrow polydisperse biopolymers the instrumental conditions are less critical in the determination of average-number mass, weight average and polydispersity, although the SECPC Mn, and weight average values are often higher than the corresponding values

  15. Development of decision tree software and protein profiling using surface enhanced laser desorption/ionization-time of flight-mass spectrometry (SELDI-TOF-MS) in papillary thyroid cancer

    International Nuclear Information System (INIS)

    Yoon, Joon Kee; An, Young Sil; Park, Bok Nam; Yoon, Seok Nam; Lee, Jun

    2007-01-01

    The aim of this study was to develop a bioinformatics software and to test it in serum samples of papillary thyroid cancer using mass spectrometry (SELDI-TOF-MS). Development of 'Protein analysis' software performing decision tree analysis was done by customizing C4.5. Sixty-one serum samples from 27 papillary thyroid cancer, 17 autoimmune thyroiditis, 17 controls were applied to 2 types of protein chips, CM10 (weak cation exchange) and IMAC3 (metal binding - Cu). Mass spectrometry was performed to reveal the protein expression profiles. Decision trees were generated using 'Protein analysis' software, and automatically detected biomarker candidates. Validation analysis was performed for CM10 chip by random sampling. Decision tree software, which can perform training and validation from profiling data, was developed. For CM10 and IMAC3 chips, 23 of 113 and 8 of 41 protein peaks were significantly different among 3 groups (ρ < 0.05), respectively. Decision tree correctly classified 3 groups with an error rate of 3.3% for CM10 and 2.0% for IMAC3, and 4 and 7 biomarker candidates were detected respectively. In 2 group comparisons, all cancer samples were correctly discriminated from non-cancer samples (error rate = 0%) for CM10 by single node and for IMAC3 by multiple nodes. Validation results from 5 test sets revealed SELDI-TOF-MS and decision tree correctly differentiated cancers from non-cancers (54/55, 98%), while predictability was moderate in 3 group classification (36/55, 65%). Our in-house software was able to successfully build decision trees and detect biomarker candidates, therefore it could be useful for biomarker discovery and clinical follow up of papillary thyroid cancer

  16. Identification of cysteinylated transthyretin, a predictive biomarker of treatment response to partially hydrolyzed guar gum in type 2 diabetes rats, by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Naito, Yuji; Ichikawa, Hiroshi; Akagiri, Satomi; Uchiyama, Kazuhiko; Takagi, Tomohisa; Handa, Osamu; Yasukawa, Zenta; Tokunaga, Makoto; Ishihara, Noriyuki; Okubo, Tsutomu; Mukai, Jun; Ohki, Makoto; Uchida, Kagehiro; Yoshikawa, Toshikazu

    2016-01-01

    Recent evidence has indicated that total fiber intake is inversely related to type 2 diabetes risk. The present study aimed to investigate the effects of chronic administration of partially hydrolyzed guar gum (PHGG), a water-soluble dietary fiber, on the occurrence of diabetes and its complications, fatty liver and nephropathy. We also identified predictive serum biomarkers of treatment response to PHGG by mass spectroscopy-based proteomic analysis using Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a good model of human non-insulin-dependent diabetes mellitus. In this study, at 5 weeks of age, OLETF rats and control strain Long-Evans Tokushima Otsuka (LETO) rats were fed a control diet or a high-fiber diet (5% PHGG) for 57 weeks. Body weight, food intake, oral glucose tolerance test, plasma insulin levels, and urine glucose and protein levels were regularly measured. Oral glucose tolerance tests (OGTT) and storage of serum in a deep freezer were conducted at the beginning of the experiment and every 4 weeks after overnight fasting during the experiments. PHGG treatment affected neither meal patterns nor the body weight of OLETF and LETO rats. Repeated measure analysis of variance revealed significant differences in fasting plasma glucose and plasma glucose at 2 h after OGTT between control OLETF (OLETF-C) rats and OLETF rats treated with PHGG (OLETF-F). The glucose response determined by the area under the curve of OGTT was significantly greater in OLETF-C rats than that in OLETF-F rats at 25 weeks of age. HOMA-IR, an index of insulin resistance, increased at 25 weeks of age in OLETF-C rats, while this increase was significantly inhibited in OLETF-F rats. At 62 weeks of age, PHGG treatment significantly improved hepatic steatosis as well as renal mesangial matrix accumulation in OLETF rats. To identify the risk marker for diabetes mellitus by SELDI-TOF MS, we collected sera from 21-week-old individuals. Among the 12 specific peaks that were risk marker candidates for diabetes mellitus, the m/z 13,720 peak was identified as that of cysteinylated transthyretin by sequencing of four tryptic peptides using tandem mass spectrometry and peak distribution around the m/z 13,720 peak in the SELDI-TOF spectra. In conclusion, we found that chronic treatment with PHGG improved insulin resistance, delayed the onset of diabetes, and inhibited the development of diabetic complications, as well as identified cysteinylated transthyretin as a predictive biomarker of treatment response to PHGG in OLETF rats.

  17. Fungal pigments inhibit the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of darkly pigmented fungi.

    Science.gov (United States)

    Buskirk, Amanda D; Hettick, Justin M; Chipinda, Itai; Law, Brandon F; Siegel, Paul D; Slaven, James E; Green, Brett J; Beezhold, Donald H

    2011-04-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to discriminate moniliaceous fungal species; however, darkly pigmented fungi yield poor fingerprint mass spectra that contain few peaks of low relative abundance. In this study, the effect of dark fungal pigments on the observed MALDI mass spectra was investigated. Peptide and protein samples containing varying concentrations of synthetic melanin or fungal pigments extracted from Aspergillus niger were analyzed by MALDI-TOF and MALDI-qTOF (quadrupole TOF) MS. Signal suppression was observed in samples containing greater than 250ng/μl pigment. Microscopic examination of the MALDI sample deposit was usually heterogeneous, with regions of high pigment concentration appearing as black. Acquisition of MALDI mass spectra from these darkly pigmented regions of the sample deposit yielded poor or no [M+H](+) ion signal. In contrast, nonpigmented regions within the sample deposit and hyphal negative control extracts of A. niger were not inhibited. This study demonstrated that dark fungal pigments inhibited the desorption/ionization process during MALDI-MS; however, these fungi may be successfully analyzed by MALDI-TOF MS when culture methods that suppress pigment expression are used. The addition of tricyclazole to the fungal growth media blocks fungal melanin synthesis and results in less melanized fungi that may be analyzed by MALDI-TOF MS. Published by Elsevier Inc.

  18. Lateral velocity distributions in laser-induced desorption of CO from Cr{sub 2}O{sub 3}(0001): experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Borowski, S.; Kluener, T.; Freund, H.J. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195, Berlin (Germany); Klinkmann, I.; Al-Shamery, K. [Fachbereich 9, Carl v. Ossietzky Universitaet Oldenburg, Postfach 2503, 26111, Oldenburg (Germany); Pykavy, M.; Staemmler, V. [Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum, Universitaetsstrasse 150, 44780, Bochum (Germany)

    2004-01-01

    Quantum state resolved determination of lateral velocity distributions in laser-induced desorption of CO from a Cr{sub 2}O{sub 3}(0001) surface is investigated. Experimentally, Doppler profiles are obtained via a (1+1{sup '})-REMPI detection scheme for various rovibrational states and desorption velocities. The experimental findings are directly compared to theoretical results from high-dimensional stochastic quantum dynamical wave packet calculations based on complete first-principles potential energy surfaces. Reasonable quantitative agreement between experiment and theory concerning the total width as well as the full width at half maximum of the lateral velocity distributions is found. Depending on the rotational state a single-peaked or a double-peaked shape of the Doppler profiles is predicted theoretically. In order to support our theoretical predictions we suggest refined experimental investigations of the state-resolved Doppler profiles with an enhanced signal to noise ratio and further theoretical studies concerning the nature of the electronically excited intermediate. (orig.)

  19. Classification of wheat varieties: Use of two-dimensional gel electrophoresis for varieties that can not be classified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry and an artificial neural network

    DEFF Research Database (Denmark)

    Jacobsen, Susanne; Nesic, Ljiljana; Petersen, Marianne Kjerstine

    2001-01-01

    Analyzing a gliadin extract by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI- TOF-MS) combined with an artificial neural network (ANN) is a suitable method for identification of wheat varieties. However, the ANN can not distinguish between all different wheat...

  20. Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality : Effect of sample preparation on MALDI-MS of synthetic polymers

    NARCIS (Netherlands)

    Kooijman, Pieter C.; Kok, Sander; Honing, Maarten

    2017-01-01

    Rationale: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides detailed and in-depth information about the molecular characteristics of synthetic polymers. To obtain the most accurate results the sample preparation parameters should be chosen to suit the sample and the

  1. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Analysis of Gram-Positive, Catalase-Negative Cocci Not Belonging to the Streptococcus or Enterococcus Genus and Benefits of Database Extension

    DEFF Research Database (Denmark)

    Christensen, Jens Jørgen; Dargis, Rimtas; Hammer, Monja

    2012-01-01

    Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry with a Bruker Daltonics microflex LT system was applied to 90 well-characterized catalase-negative, Gram-positive cocci not belonging to the streptococci or enterococci. Biotyper version 2.0.43.1 software...

  2. Localization of an O-glycosylated site in the recombinant barley alpha-amylase 1 produced in yeast and correction of the amino acid sequence using matrix-assisted laser desorption/ionization mass spectrometry of peptide mixtures

    DEFF Research Database (Denmark)

    Andersen, Jens S.; Søgaard, M; Svensson, B

    1994-01-01

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of peptide mixtures was used to characterize recombinant barley alpha-amylase 1, produced in yeast. Three peptide mixtures were generated by cleavage with CNBr, digestion with endoproteinase Lys-C and Asp-N, respectively...

  3. Classification of wheat varieties: Use of two-dimensional gel electrophoresis for varieties that can not be classified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry and an artificial neural network

    DEFF Research Database (Denmark)

    Jacobsen, Susanne; Nesic, Ljiljana; Petersen, Marianne Kjerstine

    2001-01-01

    Analyzing a gliadin extract by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI- TOF-MS) combined with an artificial neural network (ANN) is a suitable method for identification of wheat varieties. However, the ANN can not distinguish between all different wheat...... not be separated by MALDI-TOF-MS and NN....

  4. The importance of matrix-assisted laser desorption ionization–time of flight mass spectrometry for correct identification of Clostridium difficile isolated from chromID C. difficile chromogenic agar

    Directory of Open Access Journals (Sweden)

    Jonathan H.K. Chen

    2017-10-01

    Full Text Available The clinical workflow of using chromogenic agar and matrix-assisted laser desorption ionization time-of-fight mass spectrometry (MALDI-TOF MS for Clostridium difficile identification was evaluated. The addition of MALDI-TOF MS identification after the chromID C. difficile chromogenic agar culture could significantly improve the diagnostic accuracy of C. difficile.

  5. Reproducibility of serum protein profiling by systematic assessment using solid-phase extraction and matrix-assisted laser desorption/ionization mass spectrometry

    DEFF Research Database (Denmark)

    Callesen, Anne K; Christensen, René Depont; Madsen, Jonna S

    2008-01-01

    was determined by enumeration and analysis of protein signals that were detected in at least six out of nine spectra obtained by three triplicate analyses of one serum sample.A candidate for best overall performance as evaluated by the number of peaks generated and the reproducibility of mass spectra was found...... among the tested methods. Up to 418 reproducible peaks were detected in one cancer serum sample. These protein peaks can be part of a possible diagnostic profile, suggesting that this sample preparation method and data acquisition approach is suitable for large-scale analysis of serum samples......Protein profiling of human serum by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) is potentially a new diagnostic tool for early detection of human diseases, including cancer. Sample preparation is a key issue in MALDI MS and the analysis of complex samples such as serum...

  6. Quantification of captopril in urine through surface-assisted laser desorption/ionization mass spectrometry using 4-mercaptobenzoic acid-capped gold nanoparticles as an internal standard.

    Science.gov (United States)

    Chen, Wen-Tsen; Chiang, Cheng-Kang; Lin, Yang-Wei; Chang, Huan-Tsung

    2010-05-01

    We have developed a new internal standard method for the determination of the concentration of captopril (CAP) through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using gold nanoparticles (Au NPs). This approach provided linearity for CAP over the concentration range 2.5-25 microM (R(2) = 0.987), with a limit of detection (signal-to-noise ratio = 3) of 1.0 microM. The spot-to-spot variations in the concentration of CAP through SALDI-MS analyses performed in the absence and presence of the internal standard were 26% and 9%, respectively (15 measurements). This approach provides simplicity, accuracy, precision, and great reproducibility to the determination of the levels of CAP in human urine samples. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  7. Metabolomic Analysis of Oxidative and Glycolytic Skeletal Muscles by Matrix-Assisted Laser Desorption/IonizationMass Spectrometric Imaging (MALDI MSI)

    Science.gov (United States)

    Tsai, Yu-Hsuan; Garrett, Timothy J.; Carter, Christy S.; Yost, Richard A.

    2015-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers that have different physiological, morphological, biochemical, and histological characteristics. In this work, skeletal muscles extensor digitorum longus, soleus, and whole gastrocnemius were analyzed by matrix-assisted laser desorption/ionization mass spectrometry to characterize small molecule metabolites of oxidative and glycolytic muscle fiber types as well as to visualize biomarker localization. Multivariate data analysis such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed to extract significant features. Different metabolic fingerprints were observed from oxidative and glycolytic fibers. Higher abundances of biomolecules such as antioxidant anserine as well as acylcarnitines were observed in the glycolytic fibers, whereas taurine and some nucleotides were found to be localized in the oxidative fibers.

  8. Detection and Quantification of 4-Methylimidazole in Cola by Matrix-assisted Laser Desorption Ionization Mass Spectrometry with Fe2O3 Nanoparticles on Zeolite.

    Science.gov (United States)

    Fujii, Yosuke; Ding, Yuqi; Umezawa, Taichi; Akimoto, Takafumi; Xu, Jiawei; Uchida, Takashi; Fujino, Tatsuya

    2018-01-01

    Food additives generally used in carbonated drinks, such as 4-methylimidazole (4MI), caffeine (Caf?), citric acid (CA), and aspartame (Apm), were measured by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) using nanometer-sized particles of iron oxide (Fe 2 O 3 NPs). The quantification of 4MI in Coca Cola (C-cola) was carried out. In order to improve the reproducibility of the peak intensities, Fe 2 O 3 NPs loaded on ZSM5 zeolite were used as the matrix for quantification. By using 2-ethylimidazole (2EI) as the internal standard, the amount of 4MI in C-cola was determined to range from 88 to 65 μg/355 mL. The results agree with the published value (approx. 72 μg/355 mL). It was found that MALDI using Fe 2 O 3 was applicable to the quantification of 4MI in C-cola.

  9. Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of clinically important yeast species.

    Science.gov (United States)

    Stevenson, Lindsay G; Drake, Steven K; Shea, Yvonne R; Zelazny, Adrian M; Murray, Patrick R

    2010-10-01

    We evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of yeast species. Using Bruker Daltonics MALDI BioTyper software, we created a spectral database library with m/z ratios of 2,000 to 20,000 Da for 109 type and reference strains of yeast (44 species in 8 genera). The database was tested for accuracy by use of 194 clinical isolates (23 species in 6 genera). A total of 192 (99.0%) of the clinical isolates were identified accurately by MALDI-TOF MS. The MALDI-TOF MS-based method was found to be reproducible and accurate, with low consumable costs and minimal preparation time.

  10. Correlation between phosphorylation ratios by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis and radioactivities by radioactive assay.

    Science.gov (United States)

    Tsuchiya, Akira; Asai, Daisuke; Kang, Jeong-Hun; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

    2012-02-15

    To investigate the correlation between the counts per minute (CPM) by radioactivity assay and the phosphorylation ratio by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, we prepared 136 peptide substrates. The correlation coefficient of phosphorylation ratios to CPM was 0.77 for all samples. However, the more the numbers of positively charged amino acids increased, the more the correlation coefficient increased. Although positively charged amino acids can have an effect on the correlation results, MALDI-TOF MS analysis is a useful means for monitoring phosphorylated peptide and protein kinase activity instead of radioactivity assays. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Analysis of low molecular weight acids by negative mode matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Shroff, Rohit; Muck, Alexander; Svatos, Ales

    2007-01-01

    Free 9-aminoacridine base is demonstrated to be a suitable matrix for negative mode matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOFMS) analysis of a wide range of low molecular weight organic acids including aliphatic (from acetic to palmitic acid), aromatic acids, phytohormones (e.g. jasmonic and salicylic acids), and amino acids. Low limits of quantitation in the femtomolar range (jasmonic - 250 fmol; caffeic - 160 fmol and salicylic - 12.5 fmol) and linear detector response over two concentration orders in the pico- and femtomolar range are extremely encouraging for the direct study of such acids in complex biological matrices. Copyright (c) 2007 John Wiley & Sons, Ltd.

  12. Inkjet-printed gold nanoparticle surfaces for the detection of low molecular weight biomolecules by laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Marsico, Alyssa L M; Creran, Brian; Duncan, Bradley; Elci, S Gokhan; Jiang, Ying; Onasch, Timothy B; Wormhoudt, Joda; Rotello, Vincent M; Vachet, Richard W

    2015-11-01

    Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstract ᅟ.

  13. Solid sampling technique for direct detection of condensed tannins in bark by matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Ishida, Yasuyuki; Kitagawa, Kuniyuki; Goto, Kuniyoshi; Ohtani, Hajime

    2005-01-01

    A novel method for the direct analysis of condensed tannin components in bark was developed on the basis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with a simple solid sampling technique. The MALDI mass spectra obtained from the wood (bark) powder sample clearly showed a series of peaks corresponding to the sodium ion adducts of condensed tannin oligomers up to around m/z 3000. The results indicate that the condensed tannins in the bark sample used in this work mostly consist of combinations of flavan-3-ol units such as profisetinidin (PF), prorobinetinidin (PR) and prodelphinidin (PD), at least up to 10-mers (m/z approximately 3000).

  14. Direct Analysis of Triterpenes from High-Salt Fermented Cucumbers Using Infrared Matrix-Assisted Laser Desorption Electrospray Ionization (IR-MALDESI)

    Science.gov (United States)

    Ekelöf, Måns; McMurtrie, Erin K.; Nazari, Milad; Johanningsmeier, Suzanne D.; Muddiman, David C.

    2017-02-01

    High-salt samples present a challenge to mass spectrometry (MS) analysis, particularly when electrospray ionization (ESI) is used, requiring extensive sample preparation steps such as desalting, extraction, and purification. In this study, infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) coupled to a Q Exactive Plus mass spectrometer was used to directly analyze 50-μm thick slices of cucumber fermented and stored in 1 M sodium chloride brine. From the several hundred unique substances observed, three triterpenoid lipids produced by cucumbers, β-sitosterol, stigmasterol, and lupeol, were putatively identified based on exact mass and selected for structural analysis. The spatial distribution of the lipids were imaged, and the putative assignments were confirmed by tandem mass spectrometry performed directly on the same cucumber, demonstrating the capacity of the technique to deliver confident identifications from highly complex samples in molar concentrations of salt without the need for sample preparation.

  15. Hippocampal lipid differences in Alzheimer's disease: a human brain study using matrix-assisted laser desorption/ionization-imaging mass spectrometry.

    Science.gov (United States)

    Mendis, Lakshini H S; Grey, Angus C; Faull, Richard L M; Curtis, Maurice A

    2016-10-01

    Alzheimer's disease (AD), the leading cause of dementia, is pathologically characterized by β-amyloid plaques and tau tangles. However, there is also evidence of lipid dyshomeostasis-mediated AD pathology. Given the structural diversity of lipids, mass spectrometry is a useful tool for studying lipid changes in AD. Although there have been a few studies investigating lipid changes in the human hippocampus in particular, there are few reports on how lipids change in each hippocampal subfield (e.g., Cornu Ammonis [CA] 1-4, dentate gyrus [DG] etc.). Since each subfield has its own function, we postulated that there could be lipid changes that are unique to each. We used matrix-assisted laser desorption/ionization-imaging mass spectrometry to investigate specific lipid changes in each subfield in AD. Data from the hippocampus region of six age- and gender-matched normal and AD pairs were analyzed with SCiLS lab 2015b software (SCiLS GmbH, Germany; RRID:SCR_014426), using an analysis workflow developed in-house. Hematoxylin, eosin, and luxol fast blue staining were used to precisely delineate each anatomical hippocampal subfield. Putative lipid identities, which were consistent with published data, were assigned using MS/MS. Both positively and negatively charged lipid ion species were abundantly detected in normal and AD tissue. While the distribution pattern of lipids did not change in AD, the abundance of some lipids changed, consistent with trends that have been previously reported. However, our results indicated that the majority of these lipid changes specifically occur in the CA1 region. Additionally, there were many lipid changes that were specific to the DG. Matrix-assisted laser desorption/ionization-imaging mass spectrometry and our analysis workflow provide a novel method to investigate specific lipid changes in hippocampal subfields. Future work will focus on elucidating the role that specific lipid differences in each subfield play in AD pathogenesis.

  16. Micro- and Nanopatterning of Functional Organic Monolayers on Oxide-Free Silicon by Laser-Induced Photothermal Desorption

    NARCIS (Netherlands)

    Scheres, L.; Klingebiel, B.; Maat, ter J.; Giesbers, M.; Jong, de J.H.S.G.M.; Hartmann, N.; Zuilhof, H.

    2010-01-01

    The photothermal laser patterning of functional organic monolayers, prepared on oxide-free hydrogen-terminated silicon, and subsequent backfilling of the laser-written lines with a second organic monolayer that differs in its terminal functionality, is described. Since the thermal monolayer

  17. Applicability of a two-step laser desorption-ionization aerosol time-of-flight mass spectrometer for determination of chemical composition of ultrafine aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.

    2013-11-01

    This thesis is based on the construction of a two-step laser desorption-ionization aerosol time-of-flight mass spectrometer (laser AMS), which is capable of measuring 10 to 50 nm aerosol particles collected from urban and rural air at-site and in near real time. The operation and applicability of the instrument was tested with various laboratory measurements, including parallel measurements with filter collection/chromatographic analysis, and then in field experiments in urban environment and boreal forest. Ambient ultrafine aerosol particles are collected on a metal surface by electrostatic precipitation and introduced to the time-of-flight mass spectrometer (TOF-MS) with a sampling valve. Before MS analysis particles are desorbed from the sampling surface with an infrared laser and ionized with a UV laser. The formed ions are guided to the TOF-MS by ion transfer optics, separated according to their m/z ratios, and detected with a micro channel plate detector. The laser AMS was used in urban air studies to quantify the carbon cluster content in 50 nm aerosol particles. Standards for the study were produced from 50 nm graphite particles, suspended in toluene, with 72 hours of high power sonication. The results showed the average amount of carbon clusters (winter 2012, Helsinki, Finland) in 50 nm particles to be 7.2% per sample. Several fullerenes/fullerene fragments were detected during the measurements. In boreal forest measurements, the laser AMS was capable of detecting several different organic species in 10 to 50 nm particles. These included nitrogen-containing compounds, carbon clusters, aromatics, aliphatic hydrocarbons, and oxygenated hydrocarbons. A most interesting event occurred during the boreal forest measurements in spring 2011 when the chemistry of the atmosphere clearly changed during snow melt. On that time concentrations of laser AMS ions m/z 143 and 185 (10 nm particles) increased dramatically. Exactly at the same time, quinoline concentrations

  18. Nanophotonics with Surface Enhanced Coherent Raman Microscopy

    Science.gov (United States)

    Fast, Alexander

    extended samples' surfaces can be visualized with a nanoscale axial resolution providing topographic information. Finally, a platform for coherently interrogating single molecules is presented. Single-molecule limit SE-CARS on non-resonant molecules is achieved by means of 3D local field confinement in the nanojunctions between two spherical gold nanoparticles. Localized plasmon resonance of the dimer nanostructure confines the probe volume down to 1 nm3 and provides the local field enhancement necessary to reach single-molecule detection limit. Nonlinear excitation of Raman vibrations in SE-CARS microspectroscopy allows for higher image acquisition rates than in conventionally used single-molecule surface enhanced Raman spectroscopy (SERS). Therefore, data throughput is significantly improved while preserving spectral information despite the presence of the metal. Data simultaneously acquired from hundreds of nanoantennas allows to establish the peak enhancement factor from the observed count rates and define the maximum allowed local-field that preserves the integrity of the antenna. These results are paramount for the future design of time resolved single-molecule studies with multiple pulsed laser excitations, required for single-molecule coherence manipulation and quantum computing.

  19. High-spatial and high-mass resolution imaging of surface metabolites of Arabidopsis thaliana by laser desorption-ionization mass spectrometry using colloidal silver.

    Science.gov (United States)

    Jun, Ji Hyun; Song, Zhihong; Liu, Zhenjiu; Nikolau, Basil J; Yeung, Edward S; Lee, Young Jin

    2010-04-15

    High-spatial resolution and high-mass resolution techniques are developed and adopted for the mass spectrometric imaging of epicuticular lipids on the surface of Arabidopsis thaliana. Single cell level spatial resolution of approximately 12 mum was achieved by reducing the laser beam size by using an optical fiber with 25 mum core diameter in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer and improved matrix application using an oscillating capillary nebulizer. Fine chemical images of a whole flower were visualized in this high spatial resolution showing substructure of an anther and single pollen grains at the stigma and anthers. The LTQ-Orbitrap with a MALDI ion source was adopted to achieve MS imaging in high mass resolution. Specifically, isobaric silver ion adducts of C29 alkane (m/z 515.3741) and C28 aldehyde (m/z 515.3377), indistinguishable in low-resolution LTQ, can now be clearly distinguished and their chemical images could be separately constructed. In the application to roots, the high spatial resolution allowed molecular MS imaging of secondary roots and the high mass resolution allowed direct identification of lipid metabolites on root surfaces.

  20. High-Spatial and High-Mass Resolution Imaging of Surface Metabolites of Arabidopsis thaliana by Laser Desorption-Ionization Mass Spectrometry Using Colloidal Silver

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Ji Hyun; Song, Zhihong; Liu, Zhenjiu; Nikolau, Basil J.; Yeung, Edward S.; and Lee, Young Jin

    2010-03-17

    High-spatial resolution and high-mass resolution techniques are developed and adopted for the mass spectrometric imaging of epicuticular lipids on the surface of Arabidopsis thaliana. Single cell level spatial resolution of {approx}12 {micro}m was achieved by reducing the laser beam size by using an optical fiber with 25 {micro}m core diameter in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer and improved matrix application using an oscillating capillary nebulizer. Fine chemical images of a whole flower were visualized in this high spatial resolution showing substructure of an anther and single pollen grains at the stigma and anthers. The LTQ-Orbitrap with a MALDI ion source was adopted to achieve MS imaging in high mass resolution. Specifically, isobaric silver ion adducts of C29 alkane (m/z 515.3741) and C28 aldehyde (m/z 515.3377), indistinguishable in low-resolution LTQ, can now be clearly distinguished and their chemical images could be separately constructed. In the application to roots, the high spatial resolution allowed molecular MS imaging of secondary roots and the high mass resolution allowed direct identification of lipid metabolites on root surfaces.

  1. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric imaging of synthetic polymer sample spots prepared using ionic liquid matrices.

    Science.gov (United States)

    Gabriel, Stefan J; Pfeifer, Dietmar; Schwarzinger, Clemens; Panne, Ulrich; Weidner, Steffen M

    2014-03-15

    Polymer sample spots for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) prepared by the dried-droplet method often reveal ring formation accompanied by possible segregation of matrix and sample molecules as well as of the polymer homologs itself. Since the majority of sample spots are prepared by this simple and fast method, a matrix or sample preparation method that excludes such segregation has to be found. Three different ionic liquid matrices based on conventionally used aromatic compounds for MALDI-TOF MS were prepared. The formation of ionic liquids was proven by (1) H NMR spectroscopy. MALDI-Imaging mass spectrometry was applied to monitor the homogeneity. Our results show a superior sample spot homogeneity using ionic liquid matrices. Spots could be sampled several times without visible differences in the mass spectra. A frequently observed loss of matrix in the mass spectrometer vacuum was not observed. The necessary laser irradiance was reduced, which resulted in less polymer fragmentation. Ionic liquid matrices can be used to overcome segregation, a typical drawback of conventional MALDI dried-droplet preparations. Homogeneous sample spots are easy to prepare, stable in the MS vacuum and, thereby, improve the reproducibility of MALDI. Copyright © 2014 John Wiley & Sons, Ltd.

  2. The composition of liquid atmospheric pressure matrix-assisted laser desorption/ionization matrices and its effect on ionization in mass spectrometry.

    Science.gov (United States)

    Ryumin, Pavel; Cramer, Rainer

    2018-07-12

    New liquid atmospheric pressure (AP) matrix-assisted laser desorption/ionization (MALDI) matrices that produce predominantly multiply charged ions have been developed and evaluated with respect to their performance for peptide and protein analysis by mass spectrometry (MS). Both the chromophore and the viscous support liquid in these matrices were optimized for highest MS signal intensity, S/N values and maximum charge state. The best performance in both protein and peptide analysis was achieved employing light diols as matrix support liquids (e.g. ethylene glycol and propylene glycol). Investigating the influence of the chromophore, it was found that 2,5-dihydroxybenzoic acid resulted in a higher analyte ion signal intensity for the analysis of small peptides; however, larger molecules (>17 kDa) were undetectable. For larger molecules, a sample preparation based on α-cyano-4-hydroxycinnammic acid as the chromophore was developed and multiply protonated analytes with charge states of more than 50 were detected. Thus, for the first time it was possible to detect with MALDI MS proteins as large as ∼80 kDa with a high number of charge states, i.e. m/z values below 2000. Systematic investigations of various matrix support liquids have revealed a linear dependency between laser threshold energy and surface tension of the liquid MALDI sample. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Detection and imaging of chrome yellow (lead chromate) in latent prints, solid residues, and minerals by laser-desorption/ionization mass spectrometry (LDI-MS).

    Science.gov (United States)

    Zheng, Z; Pavlov, J; Attygalle, A B

    2017-06-01

    In the past, chrome yellow (lead chromate, PbCrO 4 ), a bright orange-red substance, has been widely used as an inorganic pigment in the production of paints, coatings, and plastics. Herein, we demonstrate that laser desorption/ionization mass spectrometry (LDI-MS) is a powerful tool for the detection of lead chromate in solid residues. In fact, lead chromate in trace amounts is easily detectable by LDI-MS even from residues left as latent prints. For example, a latent print obtained by stamping the exposed laterally cut surface of a pencil over 50 years old on an acetonitrile-moistened paper, was successfully imaged for both lead and chromate using a Synapt G2 HDMS mass spectrometer. After rastering the print with a 355 nm laser beam and recording positive- and negative-ion mass spectra over the range m/z 50-1200, we generated false-color 'heat maps' (single-ion images) for 208 Pb +• (m/z 207.98) and Cr 2 O 6 -• (m/z 199.85). The heat maps matched closely with the faint visual image of the pencil imprint. Moreover, our results confirmed that lead chromate was used in the pigment coatings of old pencils. Evidently, LDI-MS imaging is an efficient procedure to survey for the presence of lead and chromate in minerals and other materials. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Molecular imaging of banknote and questioned document using solvent-free gold nanoparticle-assisted laser desorption/ionization imaging mass spectrometry.

    Science.gov (United States)

    Tang, Ho-Wai; Wong, Melody Yee-Man; Chan, Sharon Lai-Fung; Che, Chi-Ming; Ng, Kwan-Ming

    2011-01-01

    Direct chemical analysis and molecular imaging of questioned documents in a non/minimal-destructive manner is important in forensic science. Here, we demonstrate that solvent-free gold-nanoparticle-assisted laser desorption/ionization mass spectrometry is a sensitive and minimal destructive method for direct detection and imaging of ink and visible and/or fluorescent dyes printed on banknotes or written on questioned documents. Argon ion sputtering of a gold foil allows homogeneous coating of a thin layer of gold nanoparticles on banknotes and checks in a dry state without delocalizing spatial distributions of the analytes. Upon N(2) laser irradiation of the gold nanoparticle-coated banknotes or checks, abundant ions are desorbed and detected. Recording the spatial distributions of the ions can reveal the molecular images of visible and fluorescent ink printed on banknotes and determine the printing order of different ink which may be useful in differentiating real banknotes from fakes. The method can also be applied to identify forged parts in questioned documents, such as number/writing alteration on a check, by tracing different writing patterns that come from different pens.

  5. Gas-phase ionization/desolvation processes and their effect on protein charge state distribution under matrix-assisted laser desorption/ionization conditions.

    Science.gov (United States)

    Alves, Sandra; Fournier, Françoise; Afonso, Carlo; Wind, Franck; Tabet, Jean-Claude

    2006-01-01

    The charge state distribution of proteins was studied as a function of experimental conditions, to improve the understanding of the matrix-assisted laser desorption/ionization (MALDI) mechanisms. The relative abundances of the multiply-charged ions appear to be a function of the matrix chosen, the laser fluence and the matrix-to-analyte molar ratio. A correlation is found between the matrix proton affinity and the yield of singly- versus multiply-charged ions. These results are in good agreement with a model in which gas-phase intracluster reactions play a significant role in analyte ion formation. A new model for endothermic desolvation processes in ultraviolet/MALDI is presented and discussed. It is based upon the existence of highly-charged precursor clusters and, complementary to the ion survivor model of Karas et al., assumes that two energy-dependent processes exist: (i) a soft desolvation involving consecutive losses of neutral matrix molecules, leading to a multiply-charged analyte and (ii) hard desolvation leading to a low charge state analyte, by consecutive losses of charged matrix molecules. These desolvations pathways are discussed in terms of kinetically limited processes. The efficiency of the two competitive desolvation processes seems related to the internal energy carried away by clusters during ablation.

  6. A method to detect metal-drug complexes and their interactions with pathogenic bacteria via graphene nanosheet assist laser desorption/ionization mass spectrometry and biosensors.

    Science.gov (United States)

    Abdelhamid, Hani Nasser; Wu, Hui-Fen

    2012-11-02

    A new method was proposed to probe the interactions between transition metals of Fe(II), Fe(III), Cu(II) with a non steroidal anti-inflammatory drug (NSAID), flufenamic acid (FF) using graphene as a matrix for Graphene assisted laser desorption ionization mass spectrometry (GALDI-MS). Metal-drug complexation was confirmed via UV absorption spectroscopy, fluorescence spectroscopy, pH meter, and change in solution conductivity. The optimal molar ratios for these complexation interactions are stoichiometry 1:2 in both Cu(II) and Fe(II) complexes, and 1:3 in Fe(III) complexes at physiological pH (7.4). Metal complexation of the drug could enhance fluorescence for 20 fold which is due to the charge transfer reaction or increase rigidity of the drug. The main interaction between graphene and flufenamic acid is the П-П interaction which allows us to probe the metal-drug complexation. The GALDI-MS could sensitively detect the drug at m/z 281.0 Da (protonated molecule) with detection limit 2.5 pmol (1.0 μM) and complexation at m/z 661.0, 654.0 and 933.0 Da corresponding to [Cu(II)(FF)(2)(H(2)O)(2)+H](+), [Fe(II)(FF)(2)(H(2)O)(2)+H](+) and [Fe(III) (FF)(3)(H(2)O)(2)+H](+), respectively (with limit of detection (LOD) 2.0 pmol (10.0 μM). Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) spectra show change in the protein profile of intact pathogenic bacteria (Pseudomonas aeroginosa, Staphylococcus aureus). The change in the ionization ability (mainly proton affinity) of pathogenic bacteria may be due to the interactions between the bacteria with the drug (or its complexes). Shielding carboxylic group by metals and increase the hydrophilicity could enhance the biocompatibility of complexes toward the pathogenic bacteria which can be used as biosensors with high sensitivity and lowest detectable concentrations are in the range of 3.3×10(3)-3.9×10(4) cfu mL(-1) with large linear dynamic range. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. A method to detect metal–drug complexes and their interactions with pathogenic bacteria via graphene nanosheet assist laser desorption/ionization mass spectrometry and biosensors

    International Nuclear Information System (INIS)

    Abdelhamid, Hani Nasser; Wu, Hui-Fen

    2012-01-01

    Highlights: ► Probe transition metals-complexes based on noncovalent functionalized graphene for MALDI-MS. ► Study interaction of transition metals complexes with pathogenic bacteria. ► Propose a new biosensor for two pathogenic bacteria. - Abstract: A new method was proposed to probe the interactions between transition metals of Fe(II), Fe(III), Cu(II) with a non steroidal anti-inflammatory drug (NSAID), flufenamic acid (FF) using graphene as a matrix for Graphene assisted laser desorption ionization mass spectrometry (GALDI-MS). Metal–drug complexation was confirmed via UV absorption spectroscopy, fluorescence spectroscopy, pH meter, and change in solution conductivity. The optimal molar ratios for these complexation interactions are stoichiometry 1:2 in both Cu(II) and Fe(II) complexes, and 1:3 in Fe(III) complexes at physiological pH (7.4). Metal complexation of the drug could enhance fluorescence for 20 fold which is due to the charge transfer reaction or increase rigidity of the drug. The main interaction between graphene and flufenamic acid is the Π–Π interaction which allows us to probe the metal–drug complexation. The GALDI-MS could sensitively detect the drug at m/z 281.0 Da (protonated molecule) with detection limit 2.5 pmol (1.0 μM) and complexation at m/z 661.0, 654.0 and 933.0 Da corresponding to [Cu(II)(FF) 2 (H 2 O) 2 + H] + , [Fe(II)(FF) 2 (H 2 O) 2 + H] + and [Fe(III) (FF) 3 (H 2 O) 2 + H] + , respectively (with limit of detection (LOD) 2.0 pmol (10.0 μM). Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) spectra show change in the protein profile of intact pathogenic bacteria (Pseudomonas aeroginosa, Staphylococcus aureus). The change in the ionization ability (mainly proton affinity) of pathogenic bacteria may be due to the interactions between the bacteria with the drug (or its complexes). Shielding carboxylic group by metals and increase the hydrophilicity could enhance the biocompatibility of complexes

  8. Laser Desorption/Ionization-Time of Flight (LDI-TOF and Matrix-Assisted Laser Desorption/Ionization - Time of Flight (MALDI – TOF mass spectrometry of an Algerian asphaltene

    Directory of Open Access Journals (Sweden)

    T. Fergoug

    2017-09-01

    Full Text Available Both LDI-TOF and MALDI-TOF Mass spectroscopy experiments of an Algerian asphaltene derived from a deposit were performed. LDI mass experiments were conducted for both linear and reflectron modes under laser wavelength/attenuation variation. The different LDI-Mass spectra show that mass distribution depends on experimental condition for masses below 1000 amu and that the average molecular weight is around 650 for the polar fraction and beyond 1000 amu for non-polar ones. The use of different matrices as CHCA, HABA and Dithranol changes slightly the aspect of the spectra.

  9. Matrix Assisted and/or Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of WO3 Clusters Formation in Gas Phase. Nanodiamonds, Fullerene, and Graphene Oxide Matrices

    Science.gov (United States)

    Ausekar, Mayuri Vilas; Mawale, Ravi Madhukar; Pazdera, Pavel; Havel, Josef

    2018-01-01

    The formation of W x O y +●/-● clusters in the gas phase was studied by laser desorption ionization (LDI) and matrix assisted laser desorption ionization (MALDI) of solid WO3. LDI produced (WO3) n + ●/- ● (n = 1-7) clusters. In MALDI, when using nano-diamonds (NDs), graphene oxide (GO), or fullerene (C60) matrices, higher mass clusters were generated. In addition to (WO3) n -● clusters, oxygen-rich or -deficient species were found in both LDI and MALDI (with the total number of clusters exceeding one hundred ≈ 137). This is the first time that such matrices have been used for the generation of(WO3) n +●/-● clusters in the gas phase, while new high mass clusters (WO3) n -● (n = 12-19) were also detected. [Figure not available: see fulltext.

  10. Matrix Assisted and/or Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of WO3 Clusters Formation in Gas Phase. Nanodiamonds, Fullerene, and Graphene Oxide Matrices

    Science.gov (United States)

    Ausekar, Mayuri Vilas; Mawale, Ravi Madhukar; Pazdera, Pavel; Havel, Josef

    2018-03-01

    The formation of W x O y +●/-● clusters in the gas phase was studied by laser desorption ionization (LDI) and matrix assisted laser desorption ionization (MALDI) of solid WO3. LDI produced (WO3) n + ●/- ● ( n = 1-7) clusters. In MALDI, when using nano-diamonds (NDs), graphene oxide (GO), or fullerene (C60) matrices, higher mass clusters were generated. In addition to (WO3) n -● clusters, oxygen-rich or -deficient species were found in both LDI and MALDI (with the total number of clusters exceeding one hundred ≈ 137). This is the first time that such matrices have been used for the generation of(WO3) n + ●/-● clusters in the gas phase, while new high mass clusters (WO3) n -● ( n = 12-19) were also detected. [Figure not available: see fulltext.

  11. Capillary isoelectric focusing of probiotic bacteria from cow's milk in tapered fused silica capillary with off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification

    Czech Academy of Sciences Publication Activity Database

    Horká, Marie; Karásek, Pavel; Šalplachta, Jiří; Růžička, F.; Vykydalová, Marie; Kubesová, Anna; Dráb, V.; Roth, Michal; Šlais, Karel

    2013-01-01

    Roč. 788, JUL (2013), s. 193-199 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GAP106/12/0522; GA MV VG20102015023 Institutional support: RVO:68081715 Keywords : capillary isoelectric focusing * matrix-assisted laser desorption/ionization time-of-flight mass spectrometry * lactic acid bacteria Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.517, year: 2013

  12. Structure determination of two conotoxins from Conus textile by a combination of matrix-assisted laser desorption/ionization time-of-flight and electrospray ionization mass spectrometry and biochemical methods

    DEFF Research Database (Denmark)

    Kalume, D E; Stenflo, J; Czerwiec, E

    2000-01-01

    Two highly modified conotoxins from the mollusc Conus textile, epsilon-TxIX and Gla(1)-TxVI, were characterized by matrix-assisted laser desorption/ionization and electrospray mass spectrometry and also by electrospray ionization tandem and triple mass spectrometry in combination with enzymatic c...... esterification was found necessary for the site-specific assignment of the Gla residues in the peptides....

  13. Ghost peaks observed after atmospheric pressure matrix-assisted laser desorption/ionization experiments may disclose new ionization mechanism of matrix-assisted hypersonic velocity impact ionization.

    Science.gov (United States)

    Moskovets, Eugene

    2015-08-30

    Understanding the mechanisms of matrix-assisted laser desorption/ionization (MALDI) promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample had been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laser-less matrix-assisted ionization. An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser had been turned off and the MALDI sample removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly and doubly charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. The observations were partially consistent

  14. Detection of α-defensin in blister fluids as potential biomarkers for bullous pemphigoid patients by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.

    Science.gov (United States)

    Wu, Ching-Ying; Lo, Li-Hua; Su, Hung; Shiea, Jentaie

    2018-04-01

    Bullous pemphigoid (BP) is a chronic blistering disease that manifests as multiple tense bullae on the limbs and body. Detecting biomarkers present in skin fluids may assist in the early diagnosis and treatment of BP. In this study, a modern mass spectrometric method was developed for screening biomarkers in blister fluids collected from patients. Blister fluids collected from BP patients and physically injured patients were analyzed and compared using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The blister fluids were mixed with MALDI matrix solution on the target plate; after drying, they were analyzed by MALDI-TOF MS. Alpha-defensins 1-3 were detected in the samples collected from all BP patients and absent in all patients with physical injuries. Therefore, alpha-defensins 1-3 are potential biomarkers for BP and can be used to differentiate between blisters caused by BP and those caused by physical injuries. Compared to traditional skin biopsy methods that use immunofluorescent stains, analyzing biomarkers in blister fluids using MALDI-TOF is a more rapid and less invasive method. MALDI-TOF-MS is a non-invasive and efficient method that is able to rapidly distinguish between blisters caused by BP and those caused by physical injuries. Copyright © 2018. Published by Elsevier B.V.

  15. Hydrazide and hydrazine reagents as reactive matrices for matrix-assisted laser desorption/ionization mass spectrometry to detect steroids with carbonyl groups.

    Science.gov (United States)

    Shigeri, Yasushi; Yasuda, Akikazu; Sakai, Masamichi; Ikeda, Shinya; Arakawa, Ryuichi; Sato, Hiroaki; Kinumi, Tomoya

    2015-01-01

    Fifty-one reagents (37 hydrazides and 14 hydrazines) were examined to determine if they could function as reactive matrices for the detection of steroids with carbonyl groups in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Among these reagents, 3-hydroxy-2-naphthoic acid hydrazide reacted most efficiently with steroids with carbonyl groups, allowing detection of them at the 1pmol level. Results from accurate mass measurement with a JMS-S3000 Spiral-TOF suggested that the ion peaks corresponding to the protonated fragment of a hydrazone were observed, in addition to the protonated molecular peaks of the resulting hydrazones ([M(D)+H](+)) and their sodium adduct ([M(D)+Na](+)). 3-Hydroxy-2-naphthoic acid hydrazide also could detect cortisol (1.93ng) spiked in a human serum certified reference material, as well as cortisone and cortisol in a human saliva sample collected in the morning. Using a combination of 3-hydroxy-2-naphthoic acid hydrazide and α- cyano-4-hydroxycinammic acid (CHCA) (3-hydroxy-2-naphthoic acid hydrazide:CHCA=4:1, v/v), even cortisone and cortisol in a human saliva sample collected in the afternoon, when levels are typically low, could be detected effectively.

  16. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass-Spectrometry (MALDI-TOF MS Based Microbial Identifications: Challenges and Scopes for Microbial Ecologists

    Directory of Open Access Journals (Sweden)

    Parveen Rahi

    2016-08-01

    Full Text Available Matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS based biotyping is an emerging technique for high-throughput and rapid microbial identification. Due to its relatively higher accuracy, comprehensive database of clinically important microorganisms and low-cost compared to other microbial identification methods, MALDI-TOF MS has started replacing existing practices prevalent in clinical diagnosis. However, applicability of MALDI-TOF MS in the area of microbial ecology research is still limited mainly due to the lack of data on non-clinical microorganisms. Intense research activities on cultivation of microbial diversity by conventional as well as by innovative and high-throughput methods has substantially increased the number of microbial species known today. This important area of research is in urgent need of rapid and reliable method(s for characterization and de-replication of microorganisms from various ecosystems. MALDI-TOF MS based characterization, in our opinion, appears to be the most suitable technique for such studies. Reliability of MALDI-TOF MS based identification method depends mainly on accuracy and width of reference databases, which need continuous expansion and improvement. In this review, we propose a common strategy to generate MALDI-TOF MS spectral database and advocated its sharing, and also discuss the role of MALDI-TOF MS based high-throughput microbial identification in microbial ecology studies.

  17. Negative Ion Laser Desorption/Ionization Time-of-Flight Mass Spectrometric Analysis of Small Molecules Using Graphitic Carbon Nitride Nanosheet Matrix.

    Science.gov (United States)

    Lin, Zian; Zheng, Jiangnan; Lin, Guo; Tang, Zhi; Yang, Xueqing; Cai, Zongwei

    2015-08-04

    Ultrathin graphitic carbon nitride (g-C3N4) nanosheets served as a novel matrix for the detection of small molecules by negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was described for the first time. In comparison with conventional organic matrices and graphene matrix, the use of g-C3N4 nanosheet matrix showed free matrix background interference and increased signal intensity in the analysis of amino acids, nucleobases, peptides, bisphenols (BPs), and nitropolycyclic aromatic hydrocarbons (nitro-PAHs). A systematic comparison of g-C3N4 nanosheets with positive and negative ion modes revealed that mass spectra produced by g-C3N4 nanosheets in negative ion mode were featured by singly deprotonated ion without matrix interference, which was rather different from the complicated alkali metal complexes in positive ion mode. Good salt tolerance and reproducibility allowed the determination of 1-nitropyrene (1-NP) in sewage, and its corresponding detection limit was lowered to 1 pmol. In addition, the ionization mechanism of the g-C3N4 nanosheets as matrix was also discussed. The work expands its application scope of g-C3N4 nanosheets and provides an alternative approach for small molecules.

  18. Gas-Phase Stability of Negatively Charged Organophosphate Metabolites Produced by Electrospray Ionization and Matrix-Assisted Laser Desorption/Ionization

    Science.gov (United States)

    Asakawa, Daiki; Mizuno, Hajime; Toyo'oka, Toshimasa

    2017-12-01

    The formation mechanisms of singly and multiply charged organophosphate metabolites by electrospray ionization (ESI) and their gas phase stabilities were investigated. Metabolites containing multiple phosphate groups, such as adenosine 5'-diphosphate (ADP), adenosine 5'-triphosphate (ATP), and D- myo-inositol-1,4,5-triphosphate (IP3) were observed as doubly deprotonated ions by negative-ion ESI mass spectrometry. Organophosphates with multiple negative charges were found to be unstable and often underwent loss of PO3 -, although singly deprotonated analytes were stable. The presence of fragments due to the loss of PO3 - in the negative-ion ESI mass spectra could result in the misinterpretation of analytical results. In contrast to ESI, matrix-assisted laser desorption ionization (MALDI) produced singly charged organophosphate metabolites with no associated fragmentation, since the singly charged anions are stable. The stability of an organophosphate metabolite in the gas phase strongly depends on its charge state. The fragmentations of multiply charged organophosphates were also investigated in detail through density functional theory calculations. [Figure not available: see fulltext.

  19. Stabilization of sialic acids in N-linked oligosaccharides and gangliosides for analysis by positive ion matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Powell, A K; Harvey, D J

    1996-01-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry of oligosaccharides and gangliosides normally causes loss of sialic acid, particularly when alpha-cyano-4-hydroxycinnamic acid is used as the matrix. In addition, the potential signal is split because both positive and, to a greater extent, negative ions are formed while signals are frequently complicated as the result of partial alkali-salt formation. In order to stabilize the sialic acid moieties under MALDI conditions and to divert all of the signal into the positive-ion mode, a method involving their conversion into methyl esters has been developed. The method is relatively rapid and produces strong positive-ion signals from N-linked oligosaccharides containing sialic acid and from gangliosides. The latter compounds are stable, even in the presence of alpha-cyano-4-hydroxycinnamic acid. They give abundant molecular (MNa+) ions, but with sufficient residual in-source fragmentation to allow the sequence of the sugar chain to be determined. The sialic acid residue is stable after methylation, irrespective of its linkage to the parent molecule.

  20. Quantitative analysis of poly- and perfluoroalkyl compounds in water matrices using high resolution mass spectrometry: optimization for a laser diode thermal desorption method.

    Science.gov (United States)

    Munoz, Gabriel; Vo Duy, Sung; Budzinski, Hélène; Labadie, Pierre; Liu, Jinxia; Sauvé, Sébastien

    2015-06-30

    An alternative analysis technique for the quantitation of 15 poly- and perfluoroalkyl substances (PFASs) in water matrices is reported. Analysis time between each sample was reduced to less than 20s, all target molecules being analyzed in a single run with the use of laser diode thermal desorption atmospheric pressure chemical ionization (LDTD/APCI) coupled with high resolution accurate mass (HRMS) orbitrap mass spectrometry. LDTD optimal settings were investigated using either one-factor-at-a-time or experimental design methodologies, while orbitrap parameters were optimized simultaneously by means of a Box-Behnken design. Following selection of an adequate sample concentration and purification procedure based on solid-phase extraction and graphite clean-up, the method was validated in an influent wastewater matrix. Environmentally significant limits of detection were reported (0.3-4ngL(-1) in wastewater and 0.03-0.2ngL(-1) in surface water) and out of the 15 target analytes, 11 showed excellent accuracies (±20% of the target values) and recovery rates (75-125%). The method was successfully applied to a selection of environmental samples, including wastewater samples in 7 locations across Canada, as well as surface and tap water samples from the Montreal region, providing insights into the degree of PFAS contamination in this area. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Identification of Lactobacillus from the saliva of adult patients with caries using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Yifei Zhang

    Full Text Available Matrix-assisted laser desorption/ionization (MALDI time-of-flight (TOF mass spectrometry (MS has been presented as a superior method for the detection of microorganisms in body fluid samples (e.g., blood, saliva, pus, etc. However, the performance of MALDI-TOF MS in routine identification of caries-related Lactobacillus isolates from saliva of adult patients with caries has not been determined. In the present study, we introduced a new MALDI-TOF MS system for identification of lactobacilli. Saliva samples were collected from 120 subjects with caries. Bacteria were isolated and cultured, and each isolate was identified by both 16S rRNA sequencing and MALDI-TOF MS. The identification results obtained by MALDI-TOF MS were concordant at the genus level with those of conventional 16S rRNA-based sequencing for 88.6% of lactobacilli (62/70 and 95.5% of non-lactobacilli (21/22. Up to 96 results could be obtained in parallel on a single MALDI target, suggesting that this is a reliable high-throughput approach for routine identification of lactobacilli. However, additional reference strains are necessary to increase the sensitivity and specificity of species-level identification.

  2. A novel cluster of Mycobacterium abscessus complex revealed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Suzuki, Hiromichi; Yoshida, Shiomi; Yoshida, Atsushi; Okuzumi, Katsuko; Fukusima, Atsuhito; Hishinuma, Akira

    2015-12-01

    Mycobacterium abscessus complex is a rapidly growing mycobacterium consisting of 3 subspecies, M. abscessus, Mycobacterium massiliense, and Mycobacterium bolletii. However, rapid and accurate species identification is difficult. We first evaluated a suitable protocol of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for distinguishing these subspecies. Then, we studied spectral signals by MALDI-TOF MS in 59 M. abscessus, 42 M. massiliense, and 2 M. bolletii. Among several specific spectral signals, 4 signals clearly differentiate M. massiliense from the other 2 subspecies, M. abscessus and M. bolletii. Moreover, 6 of the 42 M. massiliense isolates showed a spectral pattern similar to M. abscessus. These isolates correspond to the distinctive class of M. massiliense (cluster D) which is closer to M. abscessus by the previous variable number tandem repeat analysis. These results indicate that MALDI-TOF MS is not only useful for the identification of 3 subspecies of M. abscessus complex but also capable of distinguishing clusters of M. massiliense. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Analysis of cancer cell lipids using matrix-assisted laser desorption/ionization 15-T Fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    Yang, Hyo-Jik; Park, Kyu Hwan; Lim, Dong Wan; Kim, Hyun Sik; Kim, Jeongkwon

    2012-03-30

    A combination of methodologies using the extremely high mass accuracy and resolution of 15-T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) was introduced for the identification of intact cancer cell phospholipids. Lipids from a malignant glioma cell line were initially analyzed at a resolution of >200,000 and identified by setting the mass tolerance to ±1 mDa using matrix-assisted laser desorption/ionization (MALDI) 15-T FT-ICR MS in positive ion mode. In most cases, a database search of potential lipid candidates using the exact masses of the lipids yielded only one possible chemical composition. Extremely high mass accuracy (800,000), yielded well-resolved isotopic fine structures allowing for the identification of lipids by MALDI 15-T FT-ICR MS without using tandem mass spectrometric (MS/MS) analysis. Using this method, a total of 38 unique lipids were successfully identified. Copyright © 2012 John Wiley & Sons, Ltd.

  4. Differentiation of Lactobacillus brevis strains using Matrix-Assisted-Laser-Desorption-Ionization-Time-of-Flight Mass Spectrometry with respect to their beer spoilage potential.

    Science.gov (United States)

    Kern, Carola C; Vogel, Rudi F; Behr, Jürgen

    2014-06-01

    Lactobacillus (L.) brevis is one of the most frequently encountered bacteria in beer-spoilage incidents. As the species Lactobacillus brevis comprises strains showing varying ability to grow in beer, ranging from growth in low hopped wheat to highly hopped pilsner beer, differentiation and classification of L. brevis with regard to their beer-spoiling ability is of vital interest for the brewing industry. Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) has been shown as a powerful tool for species and sub-species differentiation of bacterial isolates and is increasingly used for strain-level differentiation. Seventeen L. brevis strains, representative of different spoilage types, were characterized according to their tolerance to iso-alpha-acids and their growth in wheat-, lager- and pilsner beer. MALDI-TOF MS spectra were acquired to perform strain-level identification, cluster analysis and biomarker detection. Strain-level identification was achieved in 90% out of 204 spectra. Misidentification occurred nearly exclusively among strains belonging to the same spoilage type. Though spectra of strongly beer-spoiling strains showed remarkable similarity, no decisive single markers were detected to be present in all strains of one group. However, MALDI-TOF MS spectra can be reliably assigned to the corresponding strain and thus allow to track single strains and connect them to their physiological properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

    Science.gov (United States)

    Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

    2013-01-01

    Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

  6. Gold nanoparticles bridging infra-red spectroscopy and laser desorption/ionization mass spectrometry for direct analysis of over-the-counter drug and botanical medicines.

    Science.gov (United States)

    Chau, Siu-Leung; Tang, Ho-Wai; Ng, Kwan-Ming

    2016-05-05

    With a coating of gold nanoparticles (AuNPs), over-the-counter (OTC) drugs and Chinese herbal medicine granules in KBr pellets could be analyzed by Fourier Transform Infra-red (FT-IR) spectroscopy and Surface-assisted Laser Desorption/Ionization mass spectrometry (SALDI-MS). FT-IR spectroscopy allows fast detection of major active ingredient (e.g., acetaminophen) in OTC drugs in KBr pellets. Upon coating a thin layer of AuNPs on the KBr pellet, minor active ingredients (e.g., noscapine and loratadine) in OTC drugs, which were not revealed by FT-IR, could be detected unambiguously using AuNPs-assisted LDI-MS. Moreover, phytochemical markers of Coptidis Rhizoma (i.e. berberine, palmatine and coptisine) could be quantified in the concentrated Chinese medicine (CCM) granules by the SALDI-MS using standard addition method. The quantitative results matched with those determined by high-performance liquid chromatography with ultraviolet detection. Being strongly absorbing in UV yet transparent to IR, AuNPs successfully bridged FT-IR and SALDI-MS for direct analysis of active ingredients in the same solid sample. FT-IR allowed the fast analysis of major active ingredient in drugs, while SALDI-MS allowed the detection of minor active ingredient in the presence of excipient, and also quantitation of phytochemicals in herbal granules. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Species determination and characterization of developmental stages of ticks by whole-animal matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Karger, Axel; Kampen, Helge; Bettin, Barbara; Dautel, Hans; Ziller, Mario; Hoffmann, Bernd; Süss, Jochen; Klaus, Christine

    2012-04-01

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of crude bacterial samples has been introduced as a very cost-efficient and rapid, yet highly informative tool to identify and classify bacteria. The potential of this approach to characterize whole animals, so far preferentially insects, is only evolving. Here, a simple protocol was developed to perform MALDI-MS analysis on extracts from whole ticks of 7 species and 4 developmental stages. Using commercially available software designed for the identification of bacteria, a reference database of spectra was constructed that allowed the species determination of ticks using larvae, nymphs, or adult individuals as starting material. Cluster analysis on the basis of MALDI mass spectra indicated that the primary determinant for the mass spectra was the species, followed by the developmental stages, which formed distinct clusters within the given species. With certain limitations, species identification was also possible using body parts and engorged animals. Spectra of developing Ixodes ricinus eggs showed dramatic changes with time, suggesting that, beyond its usefulness for species determination, MALDI-typing may have applications in developmental biology. Copyright © 2012 Elsevier GmbH. All rights reserved.

  8. Proteogenomic biomarkers for identification of Francisella species and subspecies by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry.

    Science.gov (United States)

    Durighello, Emie; Bellanger, Laurent; Ezan, Eric; Armengaud, Jean

    2014-10-07

    Francisella tularensis is the causative agent of tularemia. Because some Francisella strains are very virulent, this species is considered by the Centers for Disease Control and Prevention to be a potential category A bioweapon. A mass spectrometry method to quickly and robustly distinguish between virulent and nonvirulent Francisella strains is desirable. A combination of shotgun proteomics and whole-cell matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry on the Francisella tularensis subsp. holarctica LVS defined three protein biomarkers that allow such discrimination: the histone-like protein HU form B, the 10 kDa chaperonin Cpn10, and the 50S ribosomal protein L24. We established that their combined detection by whole-cell MALDI-TOF spectrum could enable (i) the identification of Francisella species, and (ii) the prediction of their virulence level, i.e., gain of a taxonomical level with the identification of Francisella tularensis subspecies. The detection of these biomarkers by MALDI-TOF mass spectrometry is straightforward because of their abundance and the absence of other abundant protein species closely related in terms of m/z. The predicted molecular weights for the three biomarkers and their presence as intense peaks were confirmed with MALDI-TOF/MS spectra acquired on Francisella philomiragia ATCC 25015 and on Francisella tularensis subsp. tularensis CCUG 2112, the most virulent Francisella subspecies.

  9. Discrimination of Bacillus anthracis Spores by Direct in-situ Analysis of Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Youngsu; Lee, Jonghee; Kim, Seongsoo [Agency for Defense Development, Daejeon (Korea, Republic of)

    2013-09-15

    The rapid and accurate identification of biological agents is a critical step in the case of bio-terror and biological warfare attacks. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been widely used for the identification of microorganisms. In this study, we describe a method for the rapid and accurate discrimination of Bacillus anthracis spores using MALDI-TOF MS. Our direct in-situ analysis of MALDI-TOF MS does not involve subsequent high-resolution mass analyses and sample preparation steps. This method allowed the detection of species-specific biomarkers from each Bacillus spores. Especially, B. anthracis spores had specific biomarker peaks at 2503, 3089, 3376, 6684, 6698, 6753, and 6840 m/z. Cluster and PCA analyses of the mass spectra of Bacillus spores revealed distinctively separated clusters and within-groups similarity. Therefore, we believe that this method is effective in the real-time identification of biological warfare agents such as B. anthracis as well as other microorganisms in the field.

  10. Discrimination of Bacillus anthracis Spores by Direct in-situ Analysis of Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry

    International Nuclear Information System (INIS)

    Jeong, Youngsu; Lee, Jonghee; Kim, Seongsoo

    2013-01-01

    The rapid and accurate identification of biological agents is a critical step in the case of bio-terror and biological warfare attacks. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been widely used for the identification of microorganisms. In this study, we describe a method for the rapid and accurate discrimination of Bacillus anthracis spores using MALDI-TOF MS. Our direct in-situ analysis of MALDI-TOF MS does not involve subsequent high-resolution mass analyses and sample preparation steps. This method allowed the detection of species-specific biomarkers from each Bacillus spores. Especially, B. anthracis spores had specific biomarker peaks at 2503, 3089, 3376, 6684, 6698, 6753, and 6840 m/z. Cluster and PCA analyses of the mass spectra of Bacillus spores revealed distinctively separated clusters and within-groups similarity. Therefore, we believe that this method is effective in the real-time identification of biological warfare agents such as B. anthracis as well as other microorganisms in the field

  11. De Novo Sequencing of Tryptic Phosphopeptides Using Matrix-Assisted Laser Desorption/Ionization Based Tandem Mass Spectrometry with Hydrogen Atom Attachment.

    Science.gov (United States)

    Asakawa, Daiki; Takahashi, Hidenori; Iwamoto, Shinichi; Tanaka, Koichi

    2018-02-20

    Phosphorylation is the most abundant protein modification, and tandem mass spectrometry (MS/MS) with radical-based fragmentation techniques has proven to be a promising method for phosphoproteomic applications, owing to its ability to determine phosphorylation sites on proteins. The radical-induced fragmentation technique involves the attachment or abstraction of hydrogen to peptides in an ion trap mass spectrometer, in a process called hydrogen attachment/abstraction dissociation (HAD), which has only been recently developed. In the present investigation, we have analyzed model phosphopeptides and phosphoprotein digests using HAD-MS/MS, combined with matrix-assisted laser desorption/ionization (MALDI), in order to demonstrate the usefulness of the HAD-MS/MS-based analytical method. The tryptic peptides were categorized as arginine- and lysine-terminated peptides, and MALDI HAD-MS/MS is found to facilitate the sequencing of arginine-terminated tryptic peptides, because of the selective observation of C-terminal side fragment ions. In contrast, MALDI HAD-MS/MS of lysine-terminated tryptic peptides produced both N- and C-terminal side fragments, such that the mass spectra were complex. The guanidination of peptide converted lysine into homoarginine, which facilitated the interpretation of MALDI HAD-MS/MS mass spectra. The present method was useful for de novo sequencing of tryptic phosphopeptides.

  12. Rapid identification and typing of Yersinia pestis and other Yersinia species by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

    Science.gov (United States)

    Ayyadurai, Saravanan; Flaudrops, Christophe; Raoult, Didier; Drancourt, Michel

    2010-11-12

    Accurate identification is necessary to discriminate harmless environmental Yersinia species from the food-borne pathogens Yersinia enterocolitica and Yersinia pseudotuberculosis and from the group A bioterrorism plague agent Yersinia pestis. In order to circumvent the limitations of current phenotypic and PCR-based identification methods, we aimed to assess the usefulness of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) protein profiling for accurate and rapid identification of Yersinia species. As a first step, we built a database of 39 different Yersinia strains representing 12 different Yersinia species, including 13 Y. pestis isolates representative of the Antiqua, Medievalis and Orientalis biotypes. The organisms were deposited on the MALDI-TOF plate after appropriate ethanol-based inactivation, and a protein profile was obtained within 6 minutes for each of the Yersinia species. When compared with a 3,025-profile database, every Yersinia species yielded a unique protein profile and was unambiguously identified. In the second step of analysis, environmental and clinical isolates of Y. pestis (n = 2) and Y. enterocolitica (n = 11) were compared to the database and correctly identified. In particular, Y. pestis was unambiguously identified at the species level, and MALDI-TOF was able to successfully differentiate the three biotypes. These data indicate that MALDI-TOF can be used as a rapid and accurate first-line method for the identification of Yersinia isolates.

  13. Enzyme-coupled nanoparticles-assisted laser desorption ionization mass spectrometry for searching for low-mass inhibitors of enzymes in complex mixtures.

    Science.gov (United States)

    Salwiński, Aleksander; Da Silva, David; Delépée, Raphaël; Maunit, Benoît

    2014-04-01

    In this report, enzyme-coupled magnetic nanoparticles (EMPs) were shown to be an effective affinity-based tool for finding specific interactions between enzymatic targets and the low-mass molecules in complex mixtures using classic MALDI-TOF apparatus. EMPs used in this work act as nonorganic matrix enabling ionization of small molecules without any interference in the low-mass range (enzyme-coupled nanoparticles-assisted laser desorption ionization MS, ENALDI MS) and simultaneously carry the superficial specific binding sites to capture inhibitors present in a studied mixture. We evaluated ENALDI approach in two complementary variations: 'ion fading' (IF-ENALDI), based on superficial adsorption of inhibitors and 'ion hunting' (IH-ENALDI), based on selective pre-concentration of inhibitors. IF-ENALDI was applied for two sets of enzyme-inhibitor pairs: tyrosinase-glabridin and trypsin-leupeptin and for the real plant sample: Sparrmannia discolor leaf and stem methanol extract. The efficacy of IH-ENALDI was shown for the pair of trypsin-leupeptin. Both ENALDI approaches pose an alternative for bioassay-guided fractionation, the common method for finding inhibitors in the complex mixtures.

  14. A novel matrix-assisted laser desorption/ionisation mass spectrometry imaging based methodology for the identification of sexual assault suspects.

    Science.gov (United States)

    Bradshaw, Robert; Wolstenholme, Rosalind; Blackledge, Robert D; Clench, Malcolm R; Ferguson, Leesa S; Francese, Simona

    2011-02-15

    An increase in the use of condoms by sexual offenders has been observed. This is likely to be due both to the risk of sexually transmitted diseases and to prevent the transfer of DNA evidence. In this scenario the detection of condom lubricants at a crime scene could aid in proving corpus delicti. Here we show a novel application of Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) for mapping the fingermark ridge pattern simultaneously to the detection of the condom lubricant within the fingermark itself. Two condom brands have been investigated to prove the concept. Condoms were handled producing lubricant-contaminated fingermarks. Images of the ridge pattern were obtained simultaneously to the detection of two lubricants, even several weeks after the fingermark deposition. The results therefore show the potential of MALDI MSI to link the suspect (identification through fingermark ridge pattern) to the crime (detection of condom lubricant) in one analysis. This would enable forensic scientists to provide evidence with stronger support in alleged cases of sexual assault. Copyright © 2011 John Wiley & Sons, Ltd.

  15. Identification of pathogenic microorganisms directly from positive blood vials by matrix-assisted laser desorption/ionization time of flight mass spectrometry

    DEFF Research Database (Denmark)

    Nonnemann, Bettina; Tvede, Michael; Bjarnsholt, Thomas

    2013-01-01

    Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) is a promising and fast method for identifying fungi and bacteria directly from positive blood cultures. Various pre-treatment methods for MALDI-TOF MS identification have been reported for this purpose. In......-house results for identification of bacterial colonies by MALDI-TOF MS using a cut-off score of 1.5 did not reduce the diagnostic accuracy compared with the recommended cut-off score of 1.8. A 3-month consecutive study of positive blood cultures was carried out in our laboratory to evaluate whether......% with the value of 1.5. The overall identification rate was 63% (cut-off 1.5) and 54% (cut-off 1.8). Seventy-seven per cent of fungal species were identified with both log scores. MALDI-TOF MS was in this study found to be a powerful tool in fast diagnosis of Gram-negative bacteria and fungi and to a lesser...

  16. Matrix-assisted laser desorption ionization-time of flight mass spectrometry: a fundamental shift in the routine practice of clinical microbiology.

    Science.gov (United States)

    Clark, Andrew E; Kaleta, Erin J; Arora, Amit; Wolk, Donna M

    2013-07-01

    Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the "nuts and bolts" of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care.

  17. Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: a Fundamental Shift in the Routine Practice of Clinical Microbiology

    Science.gov (United States)

    Clark, Andrew E.; Kaleta, Erin J.; Arora, Amit

    2013-01-01

    SUMMARY Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the “nuts and bolts” of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care. PMID:23824373

  18. Identification of medically relevant species of arthroconidial yeasts by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Kolecka, Anna; Khayhan, Kantarawee; Groenewald, Marizeth; Theelen, Bart; Arabatzis, Michael; Velegraki, Aristea; Kostrzewa, Markus; Mares, Mihai; Taj-Aldeen, Saad J; Boekhout, Teun

    2013-08-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories.

  19. Identification of Medically Relevant Species of Arthroconidial Yeasts by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    Science.gov (United States)

    Kolecka, Anna; Khayhan, Kantarawee; Groenewald, Marizeth; Theelen, Bart; Arabatzis, Michael; Velegraki, Aristea; Kostrzewa, Markus; Mares, Mihai; Taj-Aldeen, Saad J.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories. PMID:23678074

  20. Cultivable Methylobacterium species diversity in rice seeds identified with whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis.

    Science.gov (United States)

    Okumura, Marie; Fujitani, Yoshiko; Maekawa, Masahiko; Charoenpanich, Jittima; Murage, Hunja; Kimbara, Kazuhide; Sahin, Nurettin; Tani, Akio

    2017-02-01

    Methylobacterium species are methylotrophic bacteria that widely inhabit plant surfaces. In addition to studies on methylotrophs as model organisms, research has also been conducted on their mechanism of plant growth promotion as well as the species-species specificity of plant-microbe interaction. We employed whole-cell matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (WC-MS) analysis, which enables the rapid and accurate identification of bacteria at the species level, to identify Methylobacterium isolates collected from the rice seeds of different cultivars harvested in Japan, Thailand, and Kenya. Rice seeds obtained from diverse geographical locations showed different communities of Methylobacterium species. We found that M. fujisawaense, M. aquaticum, M. platani, and M. radiotolerans are the most frequently isolated species, but none were isolated as common species from 18 seed samples due to the highly biased communities in some samples. These findings will contribute to the development of formulations containing selected species that promote rice growth, though it may be necessary to customize the formulations depending on the cultivars and farm conditions. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  1. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria.

    Science.gov (United States)

    Ojima-Kato, Teruyo; Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources.

  2. Evaluation of a simple protein extraction method for species identification of clinically relevant staphylococci by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Matsuda, Naoto; Matsuda, Mari; Notake, Shigeyuki; Yokokawa, Hirohide; Kawamura, Yoshiaki; Hiramatsu, Keiichi; Kikuchi, Ken

    2012-12-01

    In clinical microbiology, bacterial identification is labor-intensive and time-consuming. A solution for this problem is the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In this study, we evaluated a modified protein extraction method of identification performed on target plates (on-plate extraction method) with MALDI-TOF (Bruker Microflex LT with Biotyper version 3.0) and compared it to 2 previously described methods: the direct colony method and a standard protein extraction method (standard extraction method). We evaluated the species of 273 clinical strains and 14 reference strains of staphylococci. All isolates were characterized using the superoxide dismutase A sequence as a reference. For the species identification, the on-plate, standard extraction, and direct colony methods identified 257 isolates (89.5%), 232 isolates (80.8%), and 173 isolates (60.2%), respectively, with statistically significant differences among the three methods (P extraction method is at least as good as standard extraction in identification rate and has the advantage of a shorter processing time.

  3. Flexible xxx-asp/asn and gly-xxx residues of equine cytochrome C in matrix-assisted laser desorption/ionization in-source decay mass spectrometry.

    Science.gov (United States)

    Takayama, Mitsuo

    2012-01-01

    The backbone flexibility of a protein has been studied from the standpoint of the susceptibility of amino acid residues to in-source decay (ISD) in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Residues more susceptible to MALDI-ISD, namely Xxx-Asp/Asn and Gly-Xxx, were identified from the discontinuous intense peak of c'-ions originating from specific cleavage at N-Cα bonds of the backbone of equine cytochrome c. The identity of the residues susceptible to ISD was consistent with the known flexible backbone amides as estimated by hydrogen/deuterium exchange (HDX) experiments. The identity of these flexible amino acid residues (Asp, Asn, and Gly) is consistent with the fact that these residues are preferred in flexible secondary structure free from intramolecular hydrogen-bonded structures such as α-helix and β-sheet. The MALDI-ISD spectrum of equine cytochrome c gave not only intense N-terminal side c'-ions originating from N-Cα bond cleavage at Xxx-Asp/Asn and Gly-Xxx residues, but also C-terminal side complement z'-ions originating from the same cleavage sites. The present study implies that MALDI-ISD can give information about backbone flexibility of proteins, comparable with the protection factors estimated by HDX.

  4. Flexible Xxx–Asp/Asn and Gly–Xxx Residues of Equine Cytochrome c in Matrix-Assisted Laser Desorption/Ionization In-Source Decay Mass Spectrometry

    Science.gov (United States)

    Takayama, Mitsuo

    2012-01-01

    The backbone flexibility of a protein has been studied from the standpoint of the susceptibility of amino acid residues to in-source decay (ISD) in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Residues more susceptible to MALDI-ISD, namely Xxx–Asp/Asn and Gly–Xxx, were identified from the discontinuous intense peak of c′-ions originating from specific cleavage at N–Cα bonds of the backbone of equine cytochrome c. The identity of the residues susceptible to ISD was consistent with the known flexible backbone amides as estimated by hydrogen/deuterium exchange (HDX) experiments. The identity of these flexible amino acid residues (Asp, Asn, and Gly) is consistent with the fact that these residues are preferred in flexible secondary structure free from intramolecular hydrogen-bonded structures such as α-helix and β-sheet. The MALDI-ISD spectrum of equine cytochrome c gave not only intense N-terminal side c′-ions originating from N–Cα bond cleavage at Xxx–Asp/Asn and Gly–Xxx residues, but also C-terminal side complement z′-ions originating from the same cleavage sites. The present study implies that MALDI-ISD can give information about backbone flexibility of proteins, comparable with the protection factors estimated by HDX. PMID:24349908

  5. Direct Analysis of hCGβcf Glycosylation in Normal and Aberrant Pregnancy by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Ray K. Iles

    2014-06-01

    Full Text Available The analysis of human chorionic gonadotropin (hCG in clinical chemistry laboratories by specific immunoassay is well established. However, changes in glycosylation are not as easily assayed and yet alterations in hCG glycosylation is associated with abnormal pregnancy. hCGβ-core fragment (hCGβcf was isolated from the urine of women, pregnant with normal, molar and hyperemesis gravidarum pregnancies. Each sample was subjected to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS analysis following dithiothreitol (DTT reduction and fingerprint spectra of peptide hCGβ 6–40 were analyzed. Samples were variably glycosylated, where most structures were small, core and largely mono-antennary. Larger single bi-antennary and mixtures of larger mono-antennary and bi-antennary moieties were also observed in some samples. Larger glycoforms were more abundant in the abnormal pregnancies and tri-antennary carbohydrate moieties were only observed in the samples from molar and hyperemesis gravidarum pregnancies. Given that such spectral profiling differences may be characteristic, development of small sample preparation for mass spectral analysis of hCG may lead to a simpler and faster approach to glycostructural analysis and potentially a novel clinical diagnostic test.

  6. Discrimination of Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Mani, Rinosh J; Thachil, Anil J; Ramachandran, Akhilesh

    2017-09-01

    Accurate and timely identification of infectious etiologies is of great significance in veterinary microbiology, especially for critical diseases such as strangles, a highly contagious disease of horses caused by Streptococcus equi subsp. equi. We evaluated a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platform for use in species- and subspecies-level identification of S. equi isolates from horses and compared it with an automated biochemical system. We used 25 clinical isolates each of S. equi subsp. equi and S. equi subsp. zooepidemicus. Using the MALDI-TOF MS platform, it was possible to correctly identify all 50 isolates to the species level. Unique mass peaks were identified in the bacterial peptide mass spectra generated by MALDI-TOF MS, which can be used for accurate subspecies-level identification of S. equi. Mass peaks (mass/charge, m/ z) 6,751.9 ± 1.4 (mean ± standard deviation) and 5,958.1 ± 1.3 were found to be unique to S. equi subsp. equi and S. equi subsp. zooepidemicus, respectively. The automated biochemical system correctly identified 47 of 50 of the isolates to the species level as S. equi, whereas at the subspecies level, 24 of 25 S. equi subsp. equi isolates and 22 of 25 S. equi subsp. zooepidemicus isolates were correctly identified. Our results indicate that MALDI-TOF MS can be used for accurate species- and subspecies-level identification of S. equi.

  7. Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Mycobacterium species, Nocardia species, and Other Aerobic Actinomycetes.

    Science.gov (United States)

    Buckwalter, S P; Olson, S L; Connelly, B J; Lucas, B C; Rodning, A A; Walchak, R C; Deml, S M; Wohlfiel, S L; Wengenack, N L

    2016-02-01

    The value of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria and yeasts is well documented in the literature. Its utility for the identification of mycobacteria and Nocardia spp. has also been reported in a limited scope. In this work, we report the specificity of MALDI-TOF MS for the identification of 162 Mycobacterium species and subspecies, 53 Nocardia species, and 13 genera (totaling 43 species) of other aerobic actinomycetes using both the MALDI-TOF MS manufacturer's supplied database(s) and a custom database generated in our laboratory. The performance of a simplified processing and extraction procedure was also evaluated, and, similar to the results in an earlier literature report, our viability studies confirmed the ability of this process to inactivate Mycobacterium tuberculosis prior to analysis. Following library construction and the specificity study, the performance of MALDI-TOF MS was directly compared with that of 16S rRNA gene sequencing for the evaluation of 297 mycobacteria isolates, 148 Nocardia species isolates, and 61 other aerobic actinomycetes isolates under routine clinical laboratory working conditions over a 6-month period. MALDI-TOF MS is a valuable tool for the identification of these groups of organisms. Limitations in the databases and in the ability of MALDI-TOF MS to rapidly identify slowly growing mycobacteria are discussed. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  8. Recent advances in matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) for in situ analysis of endogenous molecules in plants.

    Science.gov (United States)

    Qin, Liang; Zhang, Yawen; Liu, Yaqin; He, Huixin; Han, Manman; Li, Yanyan; Zeng, Maomao; Wang, Xiaodong

    2018-04-17

    Mass spectrometry imaging (MSI) as a label-free and powerful imaging technique enables in situ evaluation of a tissue metabolome and/or proteome, becoming increasingly popular in the detection of plant endogenous molecules. The characterization of structure and spatial information of endogenous molecules in plants are both very important aspects to better understand the physiological mechanism of plant organism. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a commonly-used tissue imaging technique, which requires matrix to assist in situ detection of a variety of molecules on the surface of a tissue section. In previous studies, MALDI-MSI was mostly used for the detection of molecules from animal tissue sections, compared to plant samples due to cell structural limitations, such as plant cuticles, epicuticular waxes, and cell walls. Despite the enormous progress that has been made in tissue imaging, there is still a challenge for MALDI-MSI suitable for the imaging of endogenous compounds in plants. This review summarises the recent advances in MALDI-MSI, focusing on the application of in situ detection of endogenous molecules in different plant organs, i.e. root, stem, leaf, flower, fruit, and seed. Further improvements on instrumentation sensitivity, matrix selection, image processing and sample preparation will expand the application of MALDI-MSI in plant research. Copyright © 2018 John Wiley & Sons, Ltd.

  9. Decision peptide-driven: a free software tool for accurate protein quantification using gel electrophoresis and matrix assisted laser desorption ionization time of flight mass spectrometry.

    Science.gov (United States)

    Santos, Hugo M; Reboiro-Jato, Miguel; Glez-Peña, Daniel; Nunes-Miranda, J D; Fdez-Riverola, Florentino; Carvallo, R; Capelo, J L

    2010-09-15

    The decision peptide-driven tool implements a software application for assisting the user in a protocol for accurate protein quantification based on the following steps: (1) protein separation through gel electrophoresis; (2) in-gel protein digestion; (3) direct and inverse (18)O-labeling and (4) matrix assisted laser desorption ionization time of flight mass spectrometry, MALDI analysis. The DPD software compares the MALDI results of the direct and inverse (18)O-labeling experiments and quickly identifies those peptides with paralleled loses in different sets of a typical proteomic workflow. Those peptides are used for subsequent accurate protein quantification. The interpretation of the MALDI data from direct and inverse labeling experiments is time-consuming requiring a significant amount of time to do all comparisons manually. The DPD software shortens and simplifies the searching of the peptides that must be used for quantification from a week to just some minutes. To do so, it takes as input several MALDI spectra and aids the researcher in an automatic mode (i) to compare data from direct and inverse (18)O-labeling experiments, calculating the corresponding ratios to determine those peptides with paralleled losses throughout different sets of experiments; and (ii) allow to use those peptides as internal standards for subsequent accurate protein quantification using (18)O-labeling. In this work the DPD software is presented and explained with the quantification of protein carbonic anhydrase. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  10. Evaluation of two matrix-assisted laser desorption ionization-time of flight mass spectrometry systems for identification of viridans group streptococci.

    Science.gov (United States)

    Kärpänoja, P; Harju, I; Rantakokko-Jalava, K; Haanperä, M; Sarkkinen, H

    2014-05-01

    In this study, the performances of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, MALDI Biotyper (Bruker Daltonics) and VITEK MS (bioMérieux), were evaluated in the identification of viridans group streptococci. Two collections of isolates were tested with both methods. From a panel of type collection strains (n = 54), MALDI Biotyper gave correct species-level identification for 51/54 (94 %) strains and 37/54 (69 %) strains for the VITEK MS in vitro diagnostic (IVD) method. Additionally, a collection of blood cultures isolates which had been characterized earlier with partial sequencing of 16S rRNA (n = 97) was analyzed. MALDI Biotyper classified 89 % and VITEK MS 93 % of these correctly to the group level. Comparison of species-level identification from the blood culture collection was possible for 36 strains. MALDI Biotyper identified 75 % and VITEK MS 97 % of these strains consistently. Among the clinical isolates, MALDI Biotyper misidentified 36 strains as Streptococcus pneumoniae. Nevertheless, our results suggest that the current MALDI-TOF methods are a good alternative for the identification of viridans streptococci and do perform as well as or better than commercial phenotypical methods.

  11. Differentiation of clinically relevant Mucorales Rhizopus microsporus and R. arrhizus by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Dolatabadi, Somayeh; Kolecka, Anna; Versteeg, Matthijs; de Hoog, Sybren G; Boekhout, Teun

    2015-07-01

    This study addresses the usefulness of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS for reliable identification of the two most frequently occurring clinical species of Rhizopus, namely Rhizopus arrhizus with its two varieties, arrhizus and delemar, and Rhizopus microsporus. The test-set comprised 38 isolates of clinical and environmental origin previously identified by internal transcribed spacer (ITS) sequencing of rDNA. Multi-locus sequence data targeting three gene markers (ITS, ACT, TEF ) showed two monophylic clades for Rhizopus arrhizus and Rhizopus microsporus (bootstrap values of 99 %). Cluster analysis confirmed the presence of two distinct clades within Rhizopus arrhizus representing its varieties arrhizus and delemar. The MALDI Biotyper 3.0 Microflex LT platform (Bruker Daltonics) was used to confirm the distinction between Rhizopus arrhizus and Rhizopus microsporus and the presence of two varieties within the species Rhizopus arrhizus. An in-house database of 30 reference main spectra (MSPs) was initially tested for correctness using commercially available databases of Bruker Daltonics. By challenging the database with the same strains of which an in-house database was created, automatic identification runs confirmed that MALDI-TOF MS is able to recognize the strains at the variety level. Based on principal component analysis, two MSP dendrograms were created and showed concordance with the multi-locus tree; thus, MALDI-TOF MS is a useful tool for diagnostics of mucoralean species.

  12. Ammonium Sulfate Improves Detection of Hydrophilic Quaternary Ammonium Compounds through Decreased Ion Suppression in Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry.

    Science.gov (United States)

    Sugiyama, Eiji; Masaki, Noritaka; Matsushita, Shoko; Setou, Mitsutoshi

    2015-11-17

    Hydrophilic quaternary ammonium compounds (QACs) include derivatives of carnitine (Car) or choline, which are known to have essential bioactivities. Here we developed a technique for improving the detection of hydrophilic QACs using ammonium sulfate (AS) in matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). In MALDI mass spectrometry for brain homogenates, the addition of AS greatly increased the signal intensities of Car, acetylcarnitine (AcCar), and glycerophosphocholine (GPC) by approximately 300-, 700-, and 2500-fold. The marked improvement required a higher AS concentration than that needed for suppressing the potassium adduction on phosphatidylcholine and 2,5-dihydroxybenzoic acid. Adding AS also increased the signal intensities of Car, AcCar, and GPC by approximately 10-, 20-, and 40-fold in MALDI-IMS. Consequently, the distributions of five hydrophilic QACs (Car, AcCar, GPC, choline, and phosphocholine) were simultaneously visualized by this technique. The distinct mechanism from other techniques such as improved matrix application, derivatization, or postionization suggests the great potential of AS addition to achieve higher sensitivity of MALDI-IMS for various analytes.

  13. High resolution detection of high mass proteins up to 80,000 Da via multifunctional CdS quantum dots in laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Ke, Yaotang; Kailasa, Suresh Kumar; Wu, Hui-Fen; Chen, Zhen-Yu

    2010-11-15

    CdS quantum dots (∼ 5 nm) are used as multifunctional nanoprobes as an effective matrix for large proteins, peptides and as affinity probes for the enrichment of tryptic digest proteins (lysozyme, myoglobin and cytochrome c) in laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS). The use of CdS quantum dots (CdS QDs) as the matrix allows acquisition of high resolution LDI mass spectra for large proteins (5000-80,000 Da). The enhancement of mass resolution is especially notable for large proteins such as BSA, HSA and transferrin (34-49 times) when compared with those obtained by using SA as the matrix. This technique demonstrates the potentiality of LDI-TOF-MS as an appropriate analytical tool for the analysis of high-molecular-weight biomolecules with high mass resolution. In addition, CdS QDs are also used as matrices for background-free detection of small biomolecules (peptides) and as affinity probes for the enrichment of tryptic digest proteins in LDI-TOF-MS. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Hydrophilic interaction chromatography coupled matrix assisted laser desorption/ionization mass spectrometry for molecular analysis of organic compounds in medicines, tea, and coffee

    KAUST Repository

    Wang, Renqi

    2013-01-01

    Natural occurring organic compounds from food, natural organic matter, as well as metabolic products have received intense attention in current chemical and biological studies. Examination of unknown compounds in complex sample matrices is hampered by the limited choices for data readout and molecular elucidation. Herein, we report a generic method of hydrophilic interaction chromatography (HILIC) coupled with matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the rapid characterization of ingredients in pharmaceutical compounds, tea, and coffee. The analytes were first fractionated using a cationic HILIC column prior to MALDI-MS analyses. It was found that the retention times of a compound arising from different samples were consistent under the same conditions. Accordingly, molecules can be readily characterized by both the mass and chromatographic retention time. The retention behaviors of acidic and basic compounds on the cationic HILIC column were found to be significantly influenced by the pH of mobile phases, whereas neutral compounds depicted a constant retention time at different pH. The general HILIC-MALDI-MS method is feasible for fast screening of naturally occurring organic compounds. A series of homologs can be determined if they have the same retention behavior. Their structural features can be elucidated by considering their mass differences and hydrophilic properties as determined by HILIC chromatogram. © 2013 The Royal Society of Chemistry.

  15. Improved procedures for N-terminal sulfonation of peptides for matrix-assisted laser desorption/ionization post-source decay peptide sequencing.

    Science.gov (United States)

    Wang, Dongxia; Kalb, Suzanne R; Cotter, Robert J

    2004-01-01

    Post source decay (PSD) analysis of precursor ions generated from matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a powerful tool for amino acid sequencing and primary structure analysis of proteins. N-Terminal sulfonation has become an effective derivatization strategy in facilitating de novo peptide sequencing by the formation of predominate y-type ion series in MALDI PSD spectra. Recently, an effective and inexpensive N-terminal derivatization method has been reported using 4-sulfophenyl isothiocyanate (SPITC) as the derivatization reagent (J. Mass. Spectrom. 2003; 38: 373-377). In this paper, we report an improvement in the derivatization procedure with this reagent that involves replacing an organic co-reagent with other chemicals and eliminating the use of organic solvent. The method is demonstrated on a model peptide and on tryptic digests of two proteins. The results indicate that the improved sulfonation reaction can be implemented with high efficiency under aqueous conditions and that the sensitivity of mass detection can be increased considerably. Copyright 2003 John Wiley & Sons, Ltd.

  16. Safety and Accuracy of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Highly Pathogenic Organisms

    Science.gov (United States)

    Rudrik, James T.; Perry, Michael J.; Sullivan, Maureen M.; Reiter-Kintz, Wanda; Lee, Philip A.; Pettit, Denise; Tran, Anthony; Swaney, Erin

    2017-01-01

    ABSTRACT Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) sample preparation methods, including the direct, on-plate formic acid, and ethanol/formic acid tube extraction methods, were evaluated for their ability to render highly pathogenic organisms nonviable and safe for handling in a biosafety level 2 laboratory. Of these, the tube extraction procedure was the most successful, with none of the tested strains surviving this sample preparation method. Tube extracts from several agents of bioterrorism and their near neighbors were analyzed in an eight-laboratory study to examine the utility of the Bruker Biotyper and Vitek MS MALDI-TOF MS systems and their in vitro diagnostic (IVD), research-use-only, and Security-Relevant databases, as applicable, to accurately identify these agents. Forty-six distinct strains of Bacillus anthracis, Yersinia pestis, Francisella tularensis, Burkholderia mallei, Burkholderia pseudomallei, Clostridium botulinum, Brucella melitensis, Brucella abortus, Brucella suis, and Brucella canis were extracted and distributed to participating laboratories for analysis. A total of 35 near-neighbor isolates were also analyzed. PMID:29021156

  17. Proteomic analysis of serum in patients with non-alcoholic steatohepatitis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Ulukaya, Engin; Yilmaz, Yusuf; Moshkovskii, Sergei; Karpova, Maria; Pyatnitskiy, Mikhail; Atug, Ozlen; Dolar, Enver

    2009-01-01

    We sought to investigate whether serum proteomic pattern analysis obtained using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF-MS) may help to diagnose non-alcoholic steatohepatitis (NASH) in the setting of non-alcoholic fatty liver disease (NAFLD). We enrolled 80 patients with biopsy-proven NAFLD and 19 healthy comparison subjects. Patients with NAFLD were classified according to their liver histology as having definite NASH (n = 48), borderline NASH (n = 22) or simple steatosis (n = 10). Liver ultrasound scanning was performed to assess the degree of steatosis. Mass spectra of serum samples were obtained using a Ultraflex II mass spectrometer. The highest accuracy for NASH diagnostics was reached using 15 peaks. Corresponding sensitivity and specificity values were 73.95% +/- 3.38% and 88.71% +/- 1.39%, respectively. However, mass spectra did not allow us to distinguish NASH from simple steatosis. We conclude that proteomic analyses of serum samples from NAFLD patients by MALDI TOF-MS do not seem to have a major clinical value for diagnosing NASH. However, the identification of 15 peaks in our study may help to further elucidate the pathophysiology of NASH and merits further investigation.

  18. Glycine Identification in Natural Jarosites Using Laser-Desorption Fourier Transform Mass Spectrometry: Implications for the search for life on Mars

    Energy Technology Data Exchange (ETDEWEB)

    J. Michelle Kotler; Nancy W. Hinman; Beizhan Yan; Daphne L. Stoner; Jill R. Scott

    2008-04-01

    The jarosite group minerals have received increasing attention since the discovery of jarosite by the Mars Exploration Rover-Opportunity on the Martian surface. The mineral group has the ability to incorporate foreign ions in its structure leading to investigations regarding its use as an indicator of aqueous and/or biological activity on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various worldwide locations. One of the organic cluster ions has been attributed to glycine based on results from combinations of glycine with synthetic jarosite and K2SO4. The ability to observe these organic signatures in jarosite samples with an “in situ” instrumental technique, such as employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  19. Analysis of trimethoprim, lincomycin, sulfadoxin and tylosin in swine manure using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry.

    Science.gov (United States)

    Solliec, Morgan; Massé, Daniel; Sauvé, Sébastien

    2014-10-01

    A new extraction method coupled to a high throughput sample analysis technique was developed for the determination of four veterinary antibiotics. The analytes belong to different groups of antibiotics such as chemotherapeutics, sulfonamides, lincosamides and macrolides. Trimethoprim (TMP), sulfadoxin (SFX), lincomycin (LCM) and tylosin (TYL) were extracted from lyophilized manure using a sonication extraction. McIlvaine buffer and methanol (MeOH) were used as extraction buffers, followed by cation-exchange solid phase extraction (SPE) for clean-up. Analysis was performed by laser diode thermal desorption-atmospheric pressure chemical-ionization (LDTD-APCI) tandem mass spectrometry (MS/MS) with selected reaction monitoring (SRM) detection. The LDTD is a high throughput sample introduction method that reduces total analysis time to less than 15s per sample, compared to minutes when using traditional liquid chromatography (LC). Various SPE parameters were optimized after sample extraction: the stationary phase, the extraction solvent composition, the quantity of sample extracted and sample pH. LDTD parameters were also optimized: solvent deposition, carrier gas, laser power and corona discharge. The method limit of detection (MLD) ranged from 2.5 to 8.3 µg kg(-1) while the method limit of quantification (MLQ) ranged from 8.3 to 28µgkg(-1). Calibration curves in the manure matrix showed good linearity (R(2)≥ 0.996) for all analytes and the interday and intraday coefficients of variation were below 14%. Recoveries of analytes from manure ranged from 53% to 69%. The method was successfully applied to real manure samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A second-generation ionic liquid matrix-assisted laser desorption/ionization matrix for effective mass spectrometric analysis of biodegradable polymers.

    Science.gov (United States)

    Berthod, Alain; Crank, Jeffrey A; Rundlett, Kimber L; Armstrong, Daniel W

    2009-11-01

    A second generation ionic liquid matrix (ILM), N,N-diisopropylethylammonium alpha-cyano-4-hydroxycinnamate (DEA-CHCA), was developed for the characterization of polar biodegradable polymers. It is compared with five solid matrices typically used for the characterization of these polymers and one other new ILM. It is shown that use of the ILM, DEA-CHCA, allows maximum signal with minimum laser intensity which minimizes polymer degradation. In these conditions, the DEA-CHCA ILM is able to assist in the ionization of analytes in an efficient but soft manner. These qualities produce spectra that allow an accurate and sensitive determination of the number average molecular weights, weight average m.w., and polydispersity index of labile polar polymers. With such polymers, many solid matrices produce spectra showing extensive polymer degradation leading to the underestimation of molecular weights. The distribution of intact analyte peaks obtained with the ILM DEA-CHCA allows for identification of the fine structure of complex copolymers. ILMs were much less susceptible to effects of extraction delay times on molecular weight determination than were solid matrices. The liquid nature of the matrix is an important reason for the outstanding results obtained for labile analyte polymers. No comparable results could be obtained with any known solid matrices or other ILMs. In many cases, the manufacturers' listed molecular weights and polydispersity measurements for biodegradable polymers are determined by size-exclusion chromatography and the data obtained by that method may differ considerably from the high-precision matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results presented here. Copyright 2009 John Wiley & Sons, Ltd.

  1. 1,8-Bis(dimethylamino)naphthalene/9-aminoacridine: A new binary matrix for lipid fingerprinting of intact bacteria by matrix assisted laser desorption ionization mass spectrometry

    International Nuclear Information System (INIS)

    Calvano, C.D.; Monopoli, A.; Ditaranto, N.; Palmisano, F.

    2013-01-01

    Graphical abstract: -- Highlights: •New binary matrix for less ionizable lipid analysis with no interfering peaks. •Combined MALDI and X-ray photoelectron spectroscopy (XPS) analyses. •Fast lipid fingerprint on Gram positive and Gram negative bacteria by MALDI MS. •Mapping of phospholipids by XPS imaging. •Very fast membrane lipid extraction procedure. -- Abstract: The effectiveness of a novel binary matrix composed of 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge) and 9-aminoacridine (9AA) for the direct lipid analysis of whole bacterial cells by matrix assisted laser desorption ionization mass spectrometry (MALDI MS) is demonstrated. Deprotonated analyte signals nearly free of matrix-related ions were observed in negative ion mode. The effect of the most important factors (laser energy, pulse voltage, DMAN/9AA ratio, analyte/matrix ratio) was investigated using a Box–Behnken response surface design followed by multi-response optimization in order to simultaneously maximize signal-to-noise (S/N) ratio and resolution. The chemical surface composition of single or mixed matrices was explored by X-ray photoelectron spectroscopy (XPS). Moreover, XPS imaging was used to map the spatial distribution of a model phospholipid in single or binary matrices. The DMAN/9AA binary matrix was then successfully applied to the analysis of intact Gram positive (Lactobacillus sanfranciscensis) or Gram negative (Escherichia coli) microorganisms. About fifty major membrane components (free fatty acids, mono-, di- and tri-glycerides, phospholipids, glycolipids and cardiolipins) were quickly and easily detected over a mass range spanning from ca. 200 to ca. 1600 m/z. Moreover, mass spectra with improved S/N ratio (compared to single matrices), reduced chemical noise and no formation of matrix-clusters were invariably obtained demonstrating the potential of this binary matrix to improve sensitivity

  2. Layer-by-layer thin film of reduced graphene oxide and gold nanoparticles as an effective sample plate in laser-induced desorption/ionization mass spectrometry.

    Science.gov (United States)

    Kuo, Tsung-Rong; Wang, Di-Yan; Chiu, Yu-Chen; Yeh, Yun-Chieh; Chen, Wei-Ting; Chen, Ching-Hui; Chen, Chun-Wei; Chang, Huan-Cheng; Hu, Cho-Chun; Chen, Chia-Chun

    2014-01-27

    This work demonstrated a simple platform for rapid and effective surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) measurements based on the layer structure of reduced graphene oxide (rGO) and gold nanoparticles. A multi-layer thin film was fabricated by alternate layer-by-layer depositions of rGO and gold nanoparticles (LBL rGO/AuNP). The flat and clean two-dimensional film was served as the sample plate and also functioned as the matrix in SALDI-TOF MS. By simply one-step deposition of analytes onto the LBL rGO/AuNP sample plate, the MS measurements of various homogeneous samples were ready to execute. The optimization of MS signal was reached by the variation of the layer numbers of rGO and gold nanoparticles. Also, the small molecules including amino acids, carbohydrates and peptides were successfully analyzed in SALDI-TOF MS using the LBL rGO/AuNP sample plate. The results showed that the signal intensity, S N(-1) ratio and reproducibility of SALDI-TOF spectra have been significantly improved in comparison to the uses of gold nanoparticles or α-cyano-4-hydroxy-cinnamic acid (CHCA) as the assisted matrixes. Taking the advantages of the unique properties of rGO and gold nanoparticles, the ready-to-use MS sample plate, which could absorb and dissipate laser energy to analytes quite efficiently and homogeneously, has shown great commercial potentials for MS applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. The photobase generator nifedipine as a novel matrix for the detection of polyphenols in matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Nguyen, Huu-Nghi; Tanaka, Mitsuru; Komabayashi, Genki; Matsui, Toshiro

    2016-10-01

    Matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is widely used for the detection and analysis of ionizable compounds. However, the method has less potential for the analysis of neutral compounds, such as polyphenols, owing to their lack of favorable proton-attachment or -removal groups. In this study, we reported for the first time that nifedipine (2,6-dimethyl-3,5-dicarbomethoxy-4-(2-nitrophenyl)-1,4-dihydropyridine), which is a strong photobase generator commonly used in polymerization, can abstract protons from neutral compounds in negative mode-MALDI experiments. When nifedipine (5 mg/ml) was used as a matrix reagent, the limit of detection (LOD) for epigallocatechin-3-O-gallate (EGCG) was determined to be 100 fmol/spot, which constitutes >50-fold improvement compared to the LOD obtained when trans-3-indoleacrylic acid, a matrix reagent previously reported for polyphenol detection, was used. Of the dihydropyridines investigated, only nifedipine facilitated the detection of EGCG, suggesting that the nitrosophenyl pyridine derivative of nifedipine formed by photoreduction under laser irradiation at 355 nm plays a crucial role in detecting polyphenols in negative mode. Reduced MS detection of 5-O-methylnaringenin indicated that nifedipine may preferably remove a proton from the 5-position OH group in the A ring of the flavonoid skeleton. The significant MS detection by nifedipine was extensively observed for polyphenols including flavones, flavonones, chalcones, stilbenoids and phenolic acids. In conclusion, nifedipine can act as a novel matrix for improving polyphenol detection by MALDI-MS in negative mode. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Gas phase ultraviolet and infrared spectroscopy on a partial peptide of β2-adrenoceptor SIVSF-NH2 by a laser desorption supersonic jet technique.

    Science.gov (United States)

    Ishiuchi, Shun-Ichi; Yamada, Kohei; Oba, Hikari; Wako, Hiromichi; Fujii, Masaaki

    2016-08-17

    Laser desorption supersonic jet laser spectroscopy has been applied to a penta-peptide, Ser-Ile-Val-Ser-Phe-NH2 (SIVSF-NH2), which is a partial sequence of a binding site in a β2-adrenaline receptor protein. By comparing the resonance enhanced multiphoton ionization spectrum with the ultraviolet-ultraviolet hole burning (HB) spectrum, it is concluded that only a single conformer exists. The infrared (IR) spectrum of the X-H stretching region, measured by IR dip spectroscopy, shows that all of the OH and NH groups form hydrogen bonds. The structure of SIVSF-NH2 is assigned by the combination of a force field calculation (CONFLEX) and quantum chemical calculations both in S0 and S1. Over 20 000 stable conformations, given by CONFLEX, are classified into 6987 groups and 1068 groups in which all of the NH and OH bonds are hydrogen-bonded are selected. The most stable structure in each group was geometrically optimized by density functional theory (DFT) calculations, and theoretical IR spectra were calculated for the conformers for which the energies are within 10 kJ mol(-1) of the most stable one. It has been found that the most stable and the secondmost stable conformers well-reproduce the observed IR spectrum. The vibrational frequencies in S1 were also calculated for these two conformers. According to the reproduction of the vibrational frequencies in the HB spectrum, the structure of SIVSF-NH2 is assigned to the most stable conformer, which forms a hydrogen-bonded structure corresponding to a compact, distorted version of the beta hairpin of peptides and proteins.

  5. 1,8-Bis(dimethylamino)naphthalene/9-aminoacridine: A new binary matrix for lipid fingerprinting of intact bacteria by matrix assisted laser desorption ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Calvano, C.D., E-mail: cosimadamiana.calvano@uniba.it [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Monopoli, A.; Ditaranto, N. [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Palmisano, F. [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Centro Interdipartimentale di Ricerca S.M.A.R.T., Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy)

    2013-10-10

    Graphical abstract: -- Highlights: •New binary matrix for less ionizable lipid analysis with no interfering peaks. •Combined MALDI and X-ray photoelectron spectroscopy (XPS) analyses. •Fast lipid fingerprint on Gram positive and Gram negative bacteria by MALDI MS. •Mapping of phospholipids by XPS imaging. •Very fast membrane lipid extraction procedure. -- Abstract: The effectiveness of a novel binary matrix composed of 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge) and 9-aminoacridine (9AA) for the direct lipid analysis of whole bacterial cells by matrix assisted laser desorption ionization mass spectrometry (MALDI MS) is demonstrated. Deprotonated analyte signals nearly free of matrix-related ions were observed in negative ion mode. The effect of the most important factors (laser energy, pulse voltage, DMAN/9AA ratio, analyte/matrix ratio) was investigated using a Box–Behnken response surface design followed by multi-response optimization in order to simultaneously maximize signal-to-noise (S/N) ratio and resolution. The chemical surface composition of single or mixed matrices was explored by X-ray photoelectron spectroscopy (XPS). Moreover, XPS imaging was used to map the spatial distribution of a model phospholipid in single or binary matrices. The DMAN/9AA binary matrix was then successfully applied to the analysis of intact Gram positive (Lactobacillus sanfranciscensis) or Gram negative (Escherichia coli) microorganisms. About fifty major membrane components (free fatty acids, mono-, di- and tri-glycerides, phospholipids, glycolipids and cardiolipins) were quickly and easily detected over a mass range spanning from ca. 200 to ca. 1600 m/z. Moreover, mass spectra with improved S/N ratio (compared to single matrices), reduced chemical noise and no formation of matrix-clusters were invariably obtained demonstrating the potential of this binary matrix to improve sensitivity.

  6. Ultrafast surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Keller, Emily L; Brandt, Nathaniel C; Cassabaum, Alyssa A; Frontiera, Renee R

    2015-08-07

    Ultrafast surface-enhanced Raman spectroscopy (SERS) with pico- and femtosecond time resolution has the ability to elucidate the mechanisms by which plasmons mediate chemical reactions. Here we review three important technological advances in these new methodologies, and discuss their prospects for applications in areas including plasmon-induced chemistry and sensing at very low limits of detection. Surface enhancement, arising from plasmonic materials, has been successfully incorporated with stimulated Raman techniques such as femtosecond stimulated Raman spectroscopy (FSRS) and coherent anti-Stokes Raman spectroscopy (CARS). These techniques are capable of time-resolved measurement on the femtosecond and picosecond time scale and can be used to follow the dynamics of molecules reacting near plasmonic surfaces. We discuss the potential application of ultrafast SERS techniques to probe plasmon-mediated processes, such as H2 dissociation and solar steam production. Additionally, we discuss the possibilities for high sensitivity SERS sensing using these stimulated Raman spectroscopies.

  7. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, S.; Xiao, Sanshui

    2012-01-01

    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (10(10)). (C) 2012 Optical Society of America...

  8. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, Søren; Xiao, Sanshui

    2012-01-01

    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (1010)....

  9. Surface enhanced raman spectroscopy on chip

    DEFF Research Database (Denmark)

    Hübner, Jörg; Anhøj, Thomas Aarøe; Zauner, Dan

    2007-01-01

    In this paper we report low resolution surface enhanced Raman spectra (SERS) conducted with a chip based spectrometer. The flat field spectrometer presented here is fabricated in SU-8 on silicon, showing a resolution of around 3 nm and a free spectral range of around 100 nm. The output facet...... fiber. The obtained spectra show that chip based spectrometer together with the SERS active surface can be used as Raman sensor....

  10. Enhanced Laser Desorption/Ionization Mass Spectrometric Detection of Biomolecules Using Gold Nanoparticles, Matrix, and the Coffee Ring Effect.

    Science.gov (United States)

    Marsico, Alyssa L M; Duncan, Bradley; Landis, Ryan F; Tonga, Gulen Yesilbag; Rotello, Vincent M; Vachet, Richard W

    2017-03-07

    Nanomaterials have been extensively used as alternate matrices to minimize the low molecular weight interferences observed in typical MALDI but such nanomaterials typically do not improve the spot-to-spot variability that is commonly seen. In this work, we demonstrate that nanoparticles and low matrix concentrations (ring by taking advantage of the "coffee ring" effect. Concentration of the samples in this way leads to enhanced signals when compared to conventional MALDI, with higher m/z analytes being enhanced to the greatest extent. Moreover, the ionization suppression often observed in samples with high salt concentrations can be overcome by preparing samples in this way. The ring that is formed is readily visible, allowing the laser to be focused only on spots that contain analyte. The coffee-ring effect represents a new mode by which nanomaterials can be used to enhance the MALDI-based detection of biomolecules.

  11. [Surface-enhanced Raman spectroscopy analysis of thiabendazole pesticide].

    Science.gov (United States)

    Lin, Lei; Wu, Rui-mei; Liu, Mu-hua; Wang, Xiao-bin; Yan, Lin-yuan

    2015-02-01

    Surface-enhanced Raman spectroscopy (SERS) technique was used to analyze the Raman peaks of thiabendazole pesticides in the present paper. Surface enhanced substrates of silver nanoparticle were made based on microwave technology. Raman signals of thiabendazole were collected by laser Micro-Raman spectrometer with 514. 5 and 785 nm excitation wavelengths, respectively. The Raman peaks at different excitation wavelengths were analyzed and compared. The Raman peaks 782 and 1 012 at 785 nm excitation wavelength were stronger, which were C--H out-of-plane vibrations. While 1284, 1450 and 1592 cm(-1) at 514.5 nm excitation wavelength were stronger, which were vng and C==N stretching. The study results showed that the intensity of Raman peak and Raman shift at different excitation wavelengths were different And strong Raman signals were observed at 782, 1012, 1284, 1450 and 1592 cm(-1) at 514.5 and 785 nm excitation wavelengths. These characteristic vibrational modes are characteristic Raman peaks of carbendazim pesticide. The results can provide basis for the rapid screening of pesticide residue in agricultural products and food based on Raman spectrum.

  12. Structure and Composition of Air-Plane Soots and Surrogates Analyzed by Raman Spectroscopy and Laser/Ions Desorption Mass Spectrometry

    Science.gov (United States)

    Ortega, Ismael; Chazallon, Bertrand; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier; Salm, François; Delhaye, David; Gaffié, Daniel; Yon, Jérôme

    2015-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. An aircraft exhaust plume contains species emitted by the engines, species formed in the plume from the emitted species and atmospheric species that become entrained into the plume. The majority of emitted species (gases and soot particles) are produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Emissions of soot particles by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied since many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. Most likely one of the reasons behind these discrepancies resides in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g. with respect to fuel or combustion techniques. In this work, we use Raman microscopy (266, 514 and 785 nm excitation) and ablation techniques (SIMS, Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particles produced from air-plane at different engine regimes simulating a landing and taking-off (LTO) cycle. First, the spectral parameters of the first-order Raman band of various soot samples, collected from three different sources in the frame of the MERMOSE project (http://mermose.onera.fr/): PowerJet SaM-146 turbofan (four engine regimes), CAST generator (propane fuel, four different global equivalence ratios), and Kerosene laboratory flame

  13. Surface-enhanced Raman fiberoptic sensors for remote monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, D.L.; Alarie, J.P.; Vo-Dinh, T. [Oak Ridge National Lab., TN (United States). Health Sciences Research Div.

    1995-09-01

    A new sensor design for remote surface-enhanced Raman scattering (SERS) measurements has been developed for environmental applications. The design features the modification of an optical fiber using layers of alumina microparticles and silver coatings for inducing the SERS effect at the sensing probe. A single fiber carries both the laser excitation and the SERS signal radiation, keeping optical parameters at the remote tip simple and consistent. The small tip size achievable with this configuration also demonstrates potential of this new design as a microsensor for in-situ measurement in microenvironments. Details of sensor tip fabrication and optical system design are described. SERS spectra of aqueous environmental samples acquired in-situ using the SERS sensor are also presented to illustrate the effectiveness of the SERS sensor.

  14. Coumarins as new matrices for matrix-assisted laser-desorption/ionization Fourier transform ion cyclotron resonance mass spectrometric analysis of hydrophobic compounds

    International Nuclear Information System (INIS)

    Wang, Hang; Dai, Bona; Liu, Bin; Lu, Han

    2015-01-01

    Highlights: • Coumarins were used as new MALDI matrices. • Coumarins were used for MALDI-FT ICR MS detection of hydrophobic compounds. • DCA had improvement in detection sensitivity, stability, selectivity and reproducibility. • DCA was applied to sterols detection in yeast cells. - Abstract: Hydrophobic compounds with hydroxyl, aldehyde or ketone groups are generally difficult to detect using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), because these compounds have low proton affinity and are poorly ionized by MALDI. Herein, coumarins have been used as new matrices for MALDI-MS analysis of a variety of hydrophobic compounds with low ionization efficiency, including steroids, coenzyme Q10, a cyclic lipopeptide and cholesterol oleate. Five coumarins, including coumarin, umbelliferone, esculetin, 7-hydroxycoumarin-3-carboxylic acid (HCA) and 6,7-dihydroxycoumarin-3-carboxylic acid (DCA), were compared with the conventional matrices of 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA). Coumarins with hydroxyl or carboxylic acid groups enabled detection. Taking DCA as an example, this matrix proved to be superior to DHB or CHCA in detection sensitivity, stability, spot-to-spot and sample-to-sample reproducibility, and accuracy. DCA increased the stability of the target compounds and decreased the loss of water. The [M + Na] + peaks were observed for all target compounds by adding NaCl as an additive, and the [M − H 2 O + H] + and [M + H] + peaks decreased. DCA was selected for the identification of sterols in yeast cells, and thirteen sterols were detected by Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry. This work demonstrates the potential of DCA as a new matrix for detection of hydrophobic molecules by MALDI-MS and provides an alternative tool for screening sterols in antifungal research

  15. Site-specific binding of a water molecule to the sulfa drugs sulfamethoxazole and sulfisoxazole: a laser-desorption isomer-specific UV and IR study.

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W

    2018-02-20

    To determine the preferred water molecule binding sites of the polybasic sulfa drugs sulfamethoxazole (SMX) and sulfisoxazole (SIX), we have studied their monomers and monohydrated complexes through laser-desorption conformer-specific UV and IR spectroscopy. Both the SMX and SIX monomer adopt a single conformer in the molecular beam. On the basis of their conformer-specific IR spectra in the NH stretch region, these conformers were assigned to the SMX and SIX global minimum structures, both exhibiting a staggered sulfonamide group and an intramolecular C-HO[double bond, length as m-dash]S hydrogen bond. The SMX-H 2 O and SIX-H 2 O complexes each adopt a single isomer in the molecular beam. Their isomeric structures were determined based on their isomer-specific IR spectra in the NH/OH stretch region. Quantum Theory of Atoms in Molecules analysis of the calculated electron densities revealed that in the SMX-H 2 O complex the water molecule donates an O-HN hydrogen bond to the heterocycle nitrogen atom and accepts an N-HO hydrogen bond from the sulfonamide NH group. In the SIX-H 2 O complex, however, the water molecule does not bind to the heterocycle but instead donates an O-HO[double bond, length as m-dash]S hydrogen bond to the sulfonamide group and accepts an N-HO hydrogen bond from the sulfonamide NH group. Both water complexes are additionally stabilized by a C ph -HOH 2 hydrogen bond. Interacting Quantum Atoms analysis suggests that all intermolecular hydrogen bonds are dominated by the short-range exchange-correlation contribution.

  16. Rapid, simple, and highly sensitive analysis of drugs in biological samples using thin-layer chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Kuwayama, Kenji; Tsujikawa, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

    2012-01-01

    Rapid and precise identification of toxic substances is necessary for urgent diagnosis and treatment of poisoning cases and for establishing the cause of death in postmortem examinations. However, identification of compounds in biological samples using gas chromatography and liquid chromatography coupled with mass spectrometry entails time-consuming and labor-intensive sample preparations. In this study, we examined a simple preparation and highly sensitive analysis of drugs in biological samples such as urine, plasma, and organs using thin-layer chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry (TLC/MALDI/MS). When the urine containing 3,4-methylenedioxymethamphetamine (MDMA) without sample dilution was spotted on a thin-layer chromatography (TLC) plate and was analyzed by TLC/MALDI/MS, the detection limit of the MDMA spot was 0.05 ng/spot. The value was the same as that in aqueous solution spotted on a stainless steel plate. All the 11 psychotropic compounds tested (MDMA, 4-hydroxy-3-methoxymethamphetamine, 3,4-methylenedioxyamphetamine, methamphetamine, p-hydroxymethamphetamine, amphetamine, ketamine, caffeine, chlorpromazine, triazolam, and morphine) on a TLC plate were detected at levels of 0.05-5 ng, and the type (layer thickness and fluorescence) of TLC plate did not affect detection sensitivity. In addition, when rat liver homogenate obtained after MDMA administration (10 mg/kg) was spotted on a TLC plate, MDMA and its main metabolites were identified using TLC/MALDI/MS, and the spots on a TLC plate were visualized by MALDI/imaging MS. The total analytical time from spotting of intact biological samples to the output of analytical results was within 30 min. TLC/MALDI/MS enabled rapid, simple, and highly sensitive analysis of drugs from intact biological samples and crude extracts. Accordingly, this method could be applied to rapid drug screening and precise identification of toxic substances in poisoning cases and

  17. Coumarins as new matrices for matrix-assisted laser-desorption/ionization Fourier transform ion cyclotron resonance mass spectrometric analysis of hydrophobic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hang, E-mail: hangwang@sjtu.edu.cn [Instrumental Analysis Center, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240 (China); Dai, Bona [Instrumental Analysis Center, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240 (China); Liu, Bin [Key Laboratory of Kidney Disease Pathogenesis and Intervention of Hubei Province, College of Medicine, Hubei Polytechnic University, Huangshi, Hubei 435003 (China); Lu, Han [Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine (SJTU-SM), 197, Rui Jin Er Road, Shanghai 200025 (China)

    2015-07-02

    Highlights: • Coumarins were used as new MALDI matrices. • Coumarins were used for MALDI-FT ICR MS detection of hydrophobic compounds. • DCA had improvement in detection sensitivity, stability, selectivity and reproducibility. • DCA was applied to sterols detection in yeast cells. - Abstract: Hydrophobic compounds with hydroxyl, aldehyde or ketone groups are generally difficult to detect using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), because these compounds have low proton affinity and are poorly ionized by MALDI. Herein, coumarins have been used as new matrices for MALDI-MS analysis of a variety of hydrophobic compounds with low ionization efficiency, including steroids, coenzyme Q10, a cyclic lipopeptide and cholesterol oleate. Five coumarins, including coumarin, umbelliferone, esculetin, 7-hydroxycoumarin-3-carboxylic acid (HCA) and 6,7-dihydroxycoumarin-3-carboxylic acid (DCA), were compared with the conventional matrices of 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA). Coumarins with hydroxyl or carboxylic acid groups enabled detection. Taking DCA as an example, this matrix proved to be superior to DHB or CHCA in detection sensitivity, stability, spot-to-spot and sample-to-sample reproducibility, and accuracy. DCA increased the stability of the target compounds and decreased the loss of water. The [M + Na]{sup +} peaks were observed for all target compounds by adding NaCl as an additive, and the [M − H{sub 2}O + H]{sup +} and [M + H]{sup +} peaks decreased. DCA was selected for the identification of sterols in yeast cells, and thirteen sterols were detected by Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry. This work demonstrates the potential of DCA as a new matrix for detection of hydrophobic molecules by MALDI-MS and provides an alternative tool for screening sterols in antifungal research.

  18. Imaging Mass Spectrometry by Matrix-Assisted Laser Desorption/Ionization and Stress-Strain Measurements in Iontophoresis Transepithelial Corneal Collagen Cross-Linking

    Directory of Open Access Journals (Sweden)

    Paolo Vinciguerra

    2014-01-01

    Full Text Available Purpose. To compare biomechanical effect, riboflavin penetration and distribution in transepithelial corneal collagen cross-linking with iontophoresis (I-CXL, with standard cross linking (S-CXL and current transepithelial protocol (TE-CXL. Materials and Methods. The study was divided into two different sections, considering, respectively, rabbit and human cadaver corneas. In both sections corneas were divided according to imbibition protocols and irradiation power. Imaging mass spectrometry by matrix-assisted laser desorption/ionization (MALDI-IMS and stress-strain measurements were used. Forty-eight rabbit and twelve human cadaver corneas were evaluated. Results. MALDI-IMS showed a deep riboflavin penetration throughout the corneal layers with I-CXL, with a roughly lower concentration in the deepest layers when compared to S-CXL, whereas with TE-CXL penetration was considerably less. In rabbits, there was a significant increase (by 71.9% and P=0.05 in corneal rigidity after I-CXL, when compared to controls. In humans, corneal rigidity increase was not significantly different among the subgroups. Conclusions. In rabbits, I-CXL induced a significant increase in corneal stiffness as well as better riboflavin penetration when compared to controls and TE-CXL but not to S-CXL. Stress-strain in human corneas did not show significant differences among techniques, possibly because of the small sample size of groups. In conclusion, I-CXL could be a valid alternative to S-CXL for riboflavin delivery in CXL, preserving the epithelium.

  19. Identification of Coagulase-Negative Staphylococci from Bovine Intramammary Infection by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    Science.gov (United States)

    Gonçalves, Juliano Leonel; Barreiro, Juliana Regina; Braga, Patrícia Aparecida de Campos; Prada e Silva, Luis Felipe; Eberlin, Marcos Nogueira

    2014-01-01

    Coagulase-negative staphylococci (CoNS) are among the main pathogens causing bovine intramammary infection (IMI) in many countries. However, one of the limitations related to the specific diagnosis of CoNS is the lack of an accurate, rapid, and convenient method that can differentiate the bacterial species comprising this group. The aim of this study was to evaluate the ability of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) to accurately identify CoNS species in dairy cow IMI. In addition, the study aimed to determine the frequency of CoNS species causing bovine IMI. A total of 108 bacterial isolates were diagnosed as CoNS by microbiological cultures from two milk samples collected from 21 dairy herds; the first sample was collected at the cow level (i.e., 1,242 composite samples from all quarters), while the second sample was collected at the mammary quarter level (i.e., 1,140 mammary samples collected from 285 cows). After CoNS isolation was confirmed by microbiological culture for both samples, all CoNS isolates (n = 108) were genotypically differentiated by PCR restriction fragment length polymorphism (RFLP) analysis of a partial groEL gene sequence and subjected to the MALDI-TOF MS identification procedure. MALDI-TOF MS correctly identified 103 (95.4%) of the CoNS isolates identified by PCR-RFLP at the species level. Eleven CoNS species isolated from bovine IMI were identified by PCR-RFLP, and the most prevalent species was Staphylococcus chromogenes (n = 80; 74.1%). In conclusion, MALDI-TOF MS may be a reliable alternative method for differentiating CoNS species causing bovine IMI. PMID:24622096

  20. Reliable and reproducible method for rapid identification of Nocardia species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Toyokawa, Masahiro; Kimura, Keigo; Nishi, Isao; Sunada, Atsuko; Ueda, Akiko; Sakata, Tomomi; Asari, Seishi

    2013-01-01

    Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been challenged for the identification of Nocardia species. However, the standard ethanol-formic acid extraction alone is insufficient in allowing the membrane proteins of Nocardia species to be ionized by the matrix. We therefore aimed to establish our new extraction method for the MALDI-TOF MS-based identification of Nocardia species isolates. Our modified extraction procedure is through dissociation in 0.5% Tween-20 followed by bacterial heat-inactivation, mechanical breaking of the cell wall by acid-washed glass beads and protein extraction with formic acid and acetonitrile. As reference methods for species identification, full-length 16S rRNA gene sequencing and some phenotypical tests were used. In a first step, we made our own Nocardia database by analyzing 13 strains (13 different species including N. elegans, N. otitidiscaviarum, N. asiatica, N. abscessus, N. brasiliensis, N. thailandica, N. farcinica, N. nova, N. mikamii, N. cyriacigeorgica, N. asteroids, Nocardiopsis alba, and Micromonospora sp.) and registered to the MALDI BioTyper database. Then we established our database. The analysis of 12 challenge strains using the our database gave a 100% correct identification, including 8 strains identified to the species level and 4 strains to the genus level (N. elegans, N. nova, N. farcinica, Micromonospora sp.) according to the manufacture's log score specifications. In the estimation of reproducibility of our method intended for 4 strains, both within-run and between-run reproducibility were excellent. These data indicates that our method for rapid identification of Nocardia species is with reliability, reproducibility and cost effective.

  1. Disulfide bond assignment in human interleukin-7 by matrix-assisted laser desorption/ionization mass spectroscopy and site-directed cysteine to serine mutational analysis.

    Science.gov (United States)

    Cosenza, L; Sweeney, E; Murphy, J R

    1997-12-26

    Interleukin-7 (IL-7) is a proteinaceous biological response modifier that has a bioactive tertiary structure dependent on disulfide bond formation. Disulfide bond assignments in human (h)IL-7 are based upon the results of matrix-assisted laser desorption/ionization (MALDI) mass spectroscopy and Cys to Ser mutational analyses. A gene encoding the hIL-7 was synthesized incorporating Escherichia coli codon usage bias and was used to express biologically active protein as determined by stimulation of precursor B-cell proliferation. MALDI mass spectroscopic analysis of trypsin-digested hIL-7 was performed and compared with the anticipated results of a simulated tryptic digestion. Many of the anticipated hIL-7 tryptic fragments were detected including one with a molecular mass equivalent to the sum of two polypeptides linked through a disulfide bond formed from Cys residues (Cys3 and Cys142). Subsequently, Cys to Ser substitution mutational analyses were performed. A hIL-7 variant with all six Cys substituted with Ser was found to be biologically inactive (EC50 > 1 x 10(-7) M). In contrast, a family of single disulfide bond-forming variants of hIL-7 were constructed by reintroducing Cys pairs (Cys3-Cys142, Cys35-Cys130, and Cys48-Cys93), and each could stimulate cell proliferation with an EC50 of 4 x 10(-9), 2 x 10(-8), and 2 x 10(-9) M, respectively. In single disulfide bond-forming mutants of hIL-7, the ability to stimulate cell proliferation was abolished in the presence of 2 mM dithiothreitol. The results presented strongly suggest that only a single disulfide bond is required for hIL-7 to form a tertiary structure capable of stimulating precursor B-cell proliferation.

  2. High-throughput identification of bacteria and yeast by matrix-assisted laser desorption ionization-time of flight mass spectrometry in conventional medical microbiology laboratories.

    Science.gov (United States)

    van Veen, S Q; Claas, E C J; Kuijper, Ed J

    2010-03-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitable for high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. First, we evaluated MALDI-TOF MS using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (Vitek-II, API, and biochemical tests). Discrepancies were analyzed by molecular analysis of the 16S genes. Of 327 isolates, 95.1% were identified correctly to genus level, and 85.6% were identified to species level by MALDI-TOF MS. Second, we performed a prospective validation study, including 980 clinical isolates of bacteria and yeasts. Overall performance of MALDI-TOF MS was significantly better than conventional biochemical systems for correct species identification (92.2% and 83.1%, respectively) and produced fewer incorrect genus identifications (0.1% and 1.6%, respectively). Correct species identification by MALDI-TOF MS was observed in 97.7% of Enterobacteriaceae, 92% of nonfermentative Gram-negative bacteria, 94.3% of staphylococci, 84.8% of streptococci, 84% of a miscellaneous group (mainly Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella [HACEK]), and 85.2% of yeasts. MALDI-TOF MS had significantly better performance than conventional methods for species identification of staphylococci and genus identification of bacteria belonging to HACEK group. Misidentifications by MALDI-TOF MS were clearly associated with an absence of sufficient spectra from suitable reference strains in the MALDI-TOF MS database. We conclude that MALDI-TOF MS can be implemented easily for routine identification of bacteria (except for pneumococci and viridans streptococci) and yeasts in a medical microbiological laboratory.

  3. Rapid detection of carbapenem resistance in Acinetobacter baumannii using matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Marie Kempf

    Full Text Available Rapid detection of carbapenem-resistant Acinetobacter baumannii strains is critical and will benefit patient care by optimizing antibiotic therapies and preventing outbreaks. Herein we describe the development and successful application of a mass spectrometry profile generated by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF that utilized the imipenem antibiotic for the detection of carbapenem resistance in a large series of A. baumannii clinical isolates from France and Algeria. A total of 106 A. baumannii strains including 63 well-characterized carbapenemase-producing and 43 non-carbapenemase-producing strains, as well as 43 control strains (7 carbapenem-resistant and 36 carbapenem-sensitive strains were studied. After an incubation of bacteria with imipenem for up to 4 h, the mixture was centrifuged and the supernatant analyzed by MALDI-TOF MS. The presence and absence of peaks representing imipenem and its natural metabolite was analyzed. The result was interpreted as positive for carbapenemase production if the specific peak for imipenem at 300.0 m/z disappeared during the incubation time and if the peak of the natural metabolite at 254.0 m/z increased as measured by the area under the curves leading to a ratio between the peak for imipenem and its metabolite being <0.5. This assay, which was applied to the large series of A. baumannii clinical isolates, showed a sensitivity of 100.0% and a specificity of 100.0%. Our study is the first to demonstrate that this quick and simple assay can be used as a routine tool as a point-of-care method for the identification of A. baumannii carbapenemase-producers in an effort to prevent outbreaks and the spread of uncontrollable superbugs.

  4. Identification of organic pigments in tattoo inks and permanent make-up using laser desorption ionisation mass spectrometry [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Markus Niederer

    2018-01-01

    Full Text Available Nowadays, about 12% of the European and 20% of the US population are tattooed. Rising concerns regarding consumer safety, led to legal restrictions on tattoo and permanent make-up (PMU inks. Restrictions also include bans on certain colourants. Both ink types use organic pigments for colour-giving, plus inorganic pigments for white and black and colour tones. Pigments are only sparingly soluble in common solvents and occur as suspended particles in the ink matrix. Their detection and identification therefore pose a major challenge for laboratories involved in monitoring the legal compliance of tattoo inks and PMU. We overcame this challenge by developing a direct laser desorption ionisation time-of-flight mass spectrometry method, which included an easy sample clean up. The method proved to be capable of detecting and identifying organic pigments in almost all of the tested ink samples. Method validation and routine deployment during market surveys showed the method to be fit for purpose. Pigment screening of 396 tattoo inks and 55 PMU taken from the Swiss market between 2009 and 2017 lead to the following conclusions: Pigment variety is much greater in tattoo inks (18 than in PMU (10; four prohibited pigments (Pigment Green 7, Pigment Red 122, Pigment Violet 19 and 23 were found in both ink types; for PMU, these four pigments made up 12% of the pigment findings, compared to 32% for tattoo inks. Therefore, legal compliance of PMU was at a higher level. A comparison of pigments found with those declared on tattoo ink labels clearly showed that banned pigments are rarely declared, but rather masked by listing non present legal pigments and label forging; therefore, highlighting the urgency of widespread market controls.

  5. Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: A novel statistical approach for quality scoring.

    Science.gov (United States)

    Kooijman, Pieter C; Kok, Sander J; Weusten, Jos J A M; Honing, Maarten

    2016-05-05

    Preparation of samples according to an optimized method is crucial for accurate determination of polymer sample characteristics by Matrix-Assisted Laser Desorption Ionization (MALDI) analysis. Sample preparation conditions such as matrix choice, cationization agent, deposition technique or even the deposition volume should be chosen to suit the sample of interest. Many sample preparation protocols have been developed and employed, yet finding the optimal sample preparation protocol remains a challenge. Because an objective comparison between the results of diverse protocols is not possible, "gut-feeling" or "good enough" is often decisive in the search for an optimum. This implies that sub-optimal protocols are used, leading to a loss of mass spectral information quality. To address this problem a novel analytical strategy based on MALDI imaging and statistical data processing was developed in which eight parameters were formulated to objectively quantify the quality of sample deposition and optimal MALDI matrix composition and finally sum up to an overall quality score of the sample deposition. These parameters can be established in a fully automated way using commercially available mass spectrometry imaging instruments without any hardware adjustments. With the newly developed analytical strategy the highest quality MALDI spots were selected, resulting in more reproducible and more valuable spectra for PEG in a variety of matrices. Moreover, our method enables an objective comparison of sample preparation protocols for any analyte and opens up new fields of investigation by presenting MALDI performance data in a clear and concise way. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Identification and characterization of Clostridium botulinum group III field strains by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Bano, Luca; Drigo, Ilenia; Tonon, Elena; Pascoletti, Simone; Puiatti, Cinzia; Anniballi, Fabrizio; Auricchio, Bruna; Lista, Florigio; Montecucco, Cesare; Agnoletti, Fabrizio

    2017-12-01

    Animal botulism is primarily due to botulinum neurotoxin (BoNT) types C, D or their chimeric variants C/D or D/C, produced by Clostridium botulinum group III, which appears to include the genetically indistinguishable Clostridium haemolyticum and Clostridium novyi. In the present study, we used matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI TOF MS) to identify and characterize 81 BoNT-producing Clostridia isolated in 47 episodes of animal botulism. The instrument's default database, containing no entries for Clostridium botulinum, permitted reliable identification of 26 strains at the genus level. Although supplementation of the database with reference strains enhanced the instrument's ability to identify the neurotoxic strains at the genus level, resolution was not sufficient to recognize field strains at species level. Characterization by MALDI TOF confirmed the well-documented phenotypic and genetic differences between Clostridium botulinum strains of serotypes normally implicated in human botulism (A, B, E, F) and other Clostridium species able to produce BoNTs type C and D. The chimeric and non-chimeric field strains grouped separately. In particular, very low similarity was found between two non-chimeric type C field strains isolated in the same outbreak and the other field strains. This difference was comparable with the differences among the various Clostridia species included in the study. Characterization by MALDI TOF confirmed that BoNT-producing Clostridia isolated from animals are closely related and indistinguishable at the species level from Clostridium haemolyticum and Clostridium novyi reference strains. On the contrary, there seem to be substantial differences among chimeric and some non-chimeric type C strains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Detection of ricin in complex samples by immunocapture and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Duriez, Elodie; Fenaille, François; Tabet, Jean-Claude; Lamourette, Patricia; Hilaire, Didier; Becher, François; Ezan, Eric

    2008-09-01

    Ricin, the toxin component of Ricinus communis is considered as a potential chemical weapon. Several complementary techniques are required to confirm its presence in environmental samples. Here, we report a method combining immunocapture and analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the accurate detection of different species of R. communis. Liquid environmental samples were applied to magnetic particles coated with a monoclonal antibody directed against the B-chain of the toxin. After acidic elution, tryptic peptides of the A- and B-chains were obtained by accelerated digestion with trypsin in the presence of acetonitrile. Of the 20 peptides observed by MALDI-TOF MS, three were chosen for detection ( m/ z 1013.6, m/ z 1310.6 and m/ z 1728.9, which correspond to peptides 161-LEQLAGNLR-169, 150-YTFAFGGNYDR-160, and 233-SAPDPSVITLENSWGR-248, respectively). Their selection was based on several parameters such as detection sensitivity, specificity toward ricin forms and absence of isotopic overlap with unrelated peptides. To increase assay reproducibility, stable isotope-labeled peptides were incorporated during the sample preparation phase. The final assay has a limit of detection estimated at approximately 50 ng/mL ( approximately 0.8 nM) of ricin in buffer. No interference was observed when the assay was applied to ricin-spiked milk samples. In addition, several varieties of R. communis or from different geographical origins were also shown to be detectable. The present assay provides a new tool with a total analytical time of approximately 5 h, which is particularly relevant in the context of a bioterrorist incident.

  8. Use of 1,5-diaminonaphthalene to combine matrix-assisted laser desorption/ionization in-source decay fragmentation with hydrogen/deuterium exchange.

    Science.gov (United States)

    Lemaire, Pascale; Debois, Delphine; Smargiasso, Nicolas; Quinton, Loïc; Gabelica, Valérie; De Pauw, Edwin A

    2013-08-30

    In-Source Decay (ISD) in Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry is a fast and easy top-down activation method. Our objective is to find a suitable matrix to locate the deuterons following in-solution hydrogen/deuterium exchange (HDX). This matrix must circumvent the commonly encountered undesired back-exchange reactions, in order to preserve the regioselective deuteration pattern. The 1,5-diaminonaphthalene (1,5-DAN) matrix is known to be suitable for MALDI-ISD fragmentation. MALDI Mass Spectrometry Imaging (MSI) was employed to compare 1,5-DAN and other commonly used MALDI matrices with respect to the extent of back-exchange and the uniformity of the H/D exchange profiles within the MALDI spots. We tested the back-exchange on the highly sensitive amyloid-beta peptide (1-40), and proved the regioselectivity on ubiquitin and β-endorphin. MALDI-MSI results show that 1,5-DAN leads to the least back-exchange over all the spot. MALDI-ISD fragmentation combined with H/D exchange using 1,5-DAN matrix was validated by localizing deuterons in native ubiquitin. Results agree with previous data obtained by Nuclear Magnetic Resonance (NMR) and Electron Transfer Dissociation (ETD). Moreover, 1,5-DAN matrix was used to study the H/D exchange profile of the methanol-induced helical structure of β-endorphin, and the relative protection can be explained by the polarity of residues involved in hydrogen bond formation. We found that controlling crystallization is the most important parameter when combining H/D exchange with MALDI. The 1,5-DAN matrix is characterized by a fast crystallization kinetics, and therefore gives robust and reliable H/D exchange profiles using MALDI-ISD. Copyright © 2013 John Wiley & Sons, Ltd.

  9. Laser desorption single-conformation UV and IR spectroscopy of the sulfonamide drug sulfanilamide, the sulfanilamide-water complex, and the sulfanilamide dimer.

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W

    2017-06-07

    We have studied the conformational preferences of the sulfonamide drug sulfanilamide, its dimer, and its monohydrated complex through laser desorption single-conformation UV and IR spectroscopy in a molecular beam. Based on potential energy curves for the inversion of the anilinic and the sulfonamide NH 2 groups calculated at DFT level, we suggest that the zero-point level wave function of the sulfanilamide monomer is appreciably delocalized over all four conformer wells. The sulfanilamide dimer, and the monohydrated complex each exhibit a single isomer in the molecular beam. The isomeric structures of the sulfanilamide dimer and the monohydrated sulfanilamide complex were assigned based on their conformer-specific IR spectra in the NH and OH stretch region. Quantum Theory of Atoms in Molecules (QTAIM) analysis of the calculated electron density in the water complex suggests that the water molecule is bound side-on in a hydrogen bonding pocket, donating one O-HO[double bond, length as m-dash]S hydrogen bond and accepting two hydrogen bonds, a NHO and a CHO hydrogen bond. QTAIM analysis of the dimer electron density suggests that the C i symmetry dimer structure exhibits two dominating N-HO[double bond, length as m-dash]S hydrogen bonds, and three weaker types of interactions: two CHO bonds, two CHN bonds, and a chalcogen OO interaction. Most interestingly, the molecular beam dimer structure closely resembles the R dimer unit - the dimer unit with the greatest interaction energy - of the α, γ, and δ crystal polymorphs. Interacting Quantum Atoms analysis provides evidence that the total intermolecular interaction in the dimer is dominated by the short-range exchange-correlation contribution.

  10. Rapid identification of Bacillus anthracis spores in suspicious powder samples by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Dybwad, Marius; van der Laaken, Anton L; Blatny, Janet Martha; Paauw, Armand

    2013-09-01

    Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory-based matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis method for identifying B. anthracis spores in suspicious powder samples. A reference library containing 22 different Bacillus sp. strains or hoax materials was constructed and coupled with a novel classification algorithm and standardized processing protocol for various powder samples. The method's limit of B. anthracis detection was determined to be 2.5 × 10(6) spores, equivalent to a 55-μg sample size of the crudest B. anthracis-containing powder discovered during the 2001 Amerithrax incidents. The end-to-end analysis method was able to successfully discriminate among samples containing B. anthracis spores, closely related Bacillus sp. spores, and commonly encountered hoax materials. No false-positive or -negative classifications of B. anthracis spores were observed, even when the analysis method was challenged with a wide range of other bacterial agents. The robustness of the method was demonstrated by analyzing samples (i) at an external facility using a different MALDI-TOF MS instrument, (ii) using an untrained operator, and (iii) using mixtures of Bacillus sp. spores and hoax materials. Taken together, the observed performance of the analysis method developed demonstrates its potential applicability as a rapid, specific, sensitive, robust, and cost-effective laboratory-based analysis tool for resolving incidents involving suspicious powders in less than 30 min.

  11. Identification of Bacillus anthracis by using matrix-assisted laser desorption ionization-time of flight mass spectrometry and artificial neural networks.

    Science.gov (United States)

    Lasch, Peter; Beyer, Wolfgang; Nattermann, Herbert; Stämmler, Maren; Siegbrecht, Enrico; Grunow, Roland; Naumann, Dieter

    2009-11-01

    This report demonstrates the applicability of a combination of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and chemometrics for rapid and reliable identification of vegetative cells of the causative agent of anthrax, Bacillus anthracis. Bacillus cultures were prepared under standardized conditions and inactivated according to a recently developed MS-compatible inactivation protocol for highly pathogenic microorganisms. MALDI-TOF MS was then employed to collect spectra from the microbial samples and to build up a database of bacterial reference spectra. This database comprised mass peak profiles of 374 strains from Bacillus and related genera, among them 102 strains of B. anthracis and 121 strains of B. cereus. The information contained in the database was investigated by means of visual inspection of gel view representations, univariate t tests for biomarker identification, unsupervised hierarchical clustering, and artificial neural networks (ANNs). Analysis of gel views and independent t tests suggested B. anthracis- and B. cereus group-specific signals. For example, mass spectra of B. anthracis exhibited discriminating biomarkers at 4,606, 5,413, and 6,679 Da. A systematic search in proteomic databases allowed tentative assignment of some of the biomarkers to ribosomal protein or small acid-soluble proteins. Multivariate pattern analysis by unsupervised hierarchical cluster analysis further revealed a subproteome-based taxonomy of the genus Bacillus. Superior classification accuracy was achieved when supervised ANNs were employed. For the identification of B. anthracis, independent validation of optimized ANN models yielded a diagnostic sensitivity of 100% and a specificity of 100%.

  12. Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Molds of the Fusarium Genus

    Science.gov (United States)

    Stubbe, Dirk; De Cremer, Koen; Piérard, Denis; Normand, Anne-Cécile; Piarroux, Renaud; Detandt, Monique; Hendrickx, Marijke

    2014-01-01

    The rates of infection with Fusarium molds are increasing, and a diverse number of Fusarium spp. belonging to different species complexes can cause infection. Conventional species identification in the clinical laboratory is time-consuming and prone to errors. We therefore evaluated whether matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a useful alternative. The 289 Fusarium strains from the Belgian Coordinated Collections of Microorganisms (BCCM)/Institute of Hygiene and Epidemiology Mycology (IHEM) culture collection with validated sequence-based identities and comprising 40 species were used in this study. An identification strategy was developed, applying a standardized MALDI-TOF MS assay and an in-house reference spectrum database. In vitro antifungal testing was performed to assess important differences in susceptibility between clinically relevant species/species complexes. We observed that no incorrect species complex identifications were made by MALDI-TOF MS, and 82.8% of the identifications were correct to the species level. This success rate was increased to 91% by lowering the cutoff for identification. Although the identification of the correct species complex member was not always guaranteed, antifungal susceptibility testing showed that discriminating between Fusarium species complexes can be important for treatment but is not necessarily required between members of a species complex. With this perspective, some Fusarium species complexes with closely related members can be considered as a whole, increasing the success rate of correct identifications to 97%. The application of our user-friendly MALDI-TOF MS identification approach resulted in a dramatic improvement in both time and accuracy compared to identification with the conventional method. A proof of principle of our MALDI-TOF MS approach in the clinical setting using recently isolated Fusarium strains demonstrated its validity. PMID:25411180

  13. N-Alkylpyridinium isotope quaternization for matrix-assisted laser desorption/ionization Fourier transform mass spectrometric analysis of cholesterol and fatty alcohols in human hair

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hang; Wang Haoyang; Zhang Li; Zhang Jing [Shanghai Mass Spectrometry Center, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032 (China); Guo Yinlong, E-mail: ylguo@sioc.ac.cn [Shanghai Mass Spectrometry Center, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032 (China)

    2011-03-25

    Isotope-coded reagents have been developed for labeling of amino acids, phenols and fatty acids, but not for alcohols. In this work, a simple reaction based on direct N-alkylpyridinium isotope quaternization (NAPIQ) was developed for mild derivatization of cholesterol and fatty alcohols. Different from the conventional quaternary reagents with cations on themselves, two simple and charge-neutral reagents: pyridine and d{sub 5}-pyridine directly attached N-cationic tag onto the target compounds in the presence of trifluoromethanesulfonic anhydride (Tf{sub 2}O) without tedious sample preparation. The derivatization completed in 5 min and achieved charge labeling of the target compounds, which significantly improved the detection limits of analytes by 10{sup 3}-folds in further analysis by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS). The use of commercially available d{sub 0}/d{sub 5}-pyridine pairs facilitated isotope-coded chemical derivatization and avoided the use of isotope-labeled internal standards; the excess pyridine did not affect the signals of analytes. Utility of the NAPIQ method was examined in the identification of cholesterol and fatty alcohols in small amount of human hair sample (<0.5 mg). The fluctuation of total cholesterol in human body was profiled during time by quantitatively comparing the different segments of a single strand of hair. This study combines the direct pyridinium quaternization with MALDI-FTMS, which offers a perspective and an alternative tool for the identification and quantification of substances in biological matrix by comparing d{sub 0}/d{sub 5} pairs, especially when isotope-labeled internal standards are unavailable.

  14. Characterization of petroleum products by laser-induced acoustic desorption in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer

    Science.gov (United States)

    Pinkston, David S.

    Many petroleum products, in particular large nonpolar saturated hydrocarbons, have proven difficult to analyze via mass spectrometry due to their low volatility, lack of basic or acidic groups needed for most ionization methods, and low activation energies for fragmentation after ionization. The above limitation has been addressed by using laser-induced acoustic desorption (LIAD) to evaporate nonvolatile and thermally labile petroleum components for analysis in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The gaseous neutral analytes were ionized by electron impact. Model compounds were studied first to test the viability of this method. After that, different types of asphaltenes were characterized successfully. For example, the molecular weight distribution of a North American asphaltene was determined. A comparison between asphaltene samples obtained from different geographical locations showed distinct molecular weight characteristics, possibly allowing for the determination of an unknown asphaltene sample's geographic origin. Asphaltenes were also characterized via electrospray ionization (ESI) in a linear quadrupole ion trap (LQIT). The observed molecular weight distribution had an extended tail past 2000 Da. Collision-activated dissociation (CAD) experiments on isolated ions revealed that water aggregation was present in this analysis. The observed molecular weight distribution of asphaltenes reduced dramatically when water was eliminated from the system. The usefulness of a new chemical ionization reagent, ClMn(H2O) +, is also discussed. This reagent has been shown to ionize hydrocarbons without fragmentation to yield [ClMnR]+, where R is the hydrocarbon, thus providing molecular weight information. CAD of the [ClMnR]+ ions is demonstrated to allow the differentiation of isomeric hydrocarbons. Finally, the LIAD/ClMn(H2O)+ mass spectrometric method was applied to the successful analysis of various petroleum fractions and asphaltene

  15. Chemical analysis of pharmaceuticals and explosives in fingermarks using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.

    Science.gov (United States)

    Kaplan-Sandquist, Kimberly; LeBeau, Marc A; Miller, Mark L

    2014-02-01

    Chemical analysis of latent fingermarks, "touch chemistry," has the potential of providing intelligence or forensically relevant information. Matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF MS) was used as an analytical platform for obtaining mass spectra and chemical images of target drugs and explosives in fingermark residues following conventional fingerprint development methods and MALDI matrix processing. There were two main purposes of this research: (1) develop effective laboratory methods for detecting drugs and explosives in fingermark residues and (2) determine the feasibility of detecting drugs and explosives after casual contact with pills, powders, and residues. Further, synthetic latent print reference pads were evaluated as mimics of natural fingermark residue to determine if the pads could be used for method development and quality control. The results suggest that artificial amino acid and sebaceous oil residue pads are not suitable to adequately simulate natural fingermark chemistry for MALDI/TOF MS analysis. However, the pads were useful for designing experiments and setting instrumental parameters. Based on the natural fingermark residue experiments, handling whole or broken pills did not transfer sufficient quantities of drugs to allow for definitive detection. Transferring drugs or explosives in the form of powders and residues was successful for preparing analytes for detection after contact with fingers and deposition of fingermark residue. One downfall to handling powders was that the analyte particles were easily spread beyond the original fingermark during development. Analyte particles were confined in the original fingermark when using transfer residues. The MALDI/TOF MS was able to detect procaine, pseudoephedrine, TNT, and RDX from contact residue under laboratory conditions with the integration of conventional fingerprint development methods and MALDI matrix. MALDI/TOF MS is a nondestructive

  16. Matrix-assisted laser desorption/ionization mass spectrometry imaging of cell cultures for the lipidomic analysis of potential lipid markers in human breast cancer invasion.

    Science.gov (United States)

    Wang, Shujuan; Chen, Xiaowu; Luan, Hemi; Gao, Dan; Lin, Shuhai; Cai, Zongwei; Liu, Jianjun; Liu, Hongxia; Jiang, Yuyang

    2016-02-28

    Breast cancer is the leading cause of cancer death among women worldwide. Identification of lipid targets that play a role in breast cancer invasion may advance our understanding of the rapid progression of cancer and may lead to the development of new biomarkers for the disease. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) was applied for the lipidomic profiling of two poorly invasive and two highly invasive breast cancer cell lines to identify the differentially accumulated lipids related to the invasive phenotype. The four cell lines were individually grown on indium tin oxide (ITO)-coated glass slides, analyzed as cell cultures. The raster width and matrix for detection were optimized to improve detection sensitivity. Optimized MSI measurements were performed directly on the cell culture with 9-aminoacridine as matrix, resulting in 215 endogenous compounds detected in positive ion mode and 267 endogenous compounds in negative ion mode in all the four cell lines, representing the largest group of analytes that have been analyzed from cells by a single MSI study. In highly invasive cell lines, 31 lipids including phosphatidylglycerol (PG) and phosphatidic acids were found upregulated and eight lipids including sphingomyelin (SM) downregulated in negative ion mode. The products of de novo fatty acid synthesis incorporated into membrane phospholipids, like oleic-acid-containing PG, may be involved in mitochondrial dysfunction and thus affect the invasion of breast cancer cells. The deficiency of SM may be related to the disruption of apoptosis in highly invasive cancer cells. This work uncovered more analytes in cells by MSI than previous reports, providing a better visualization and novel insights to advance our understanding of the relationship between rapid progression of breast cancer and lipid metabolism. The most altered lipids may aid the discovery of diagnostic markers and therapeutic targets of breast cancer. Copyright

  17. Efficient identification of Malassezia yeasts by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Kolecka, A; Khayhan, K; Arabatzis, M; Velegraki, A; Kostrzewa, M; Andersson, A; Scheynius, A; Cafarchia, C; Iatta, R; Montagna, M T; Youngchim, S; Cabañes, F J; Hoopman, P; Kraak, B; Groenewald, M; Boekhout, T

    2014-02-01

    Infections caused by Malassezia yeasts are most likely underdiagnosed, because fatty acid supplementation is needed for growth. Rapid identification of Malassezia species is essential for appropriate treatment of Malassezia-related skin infections, fungaemia and nosocomial outbreaks in neonates, children and adults and can be life-saving for those patients. Ma-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been reported to be a rapid and reliable diagnostic tool to identify clinically important yeasts, but so far no data have been reported on identification of Malassezia isolates with this technique. To create an extensive database of main mass spectra (MSPs) that will allow quick identification of Malassezia species by MALDI-TOF MS. An in-house library of 113 MSPs was created from 48 reference strains from the CBS-KNAW yeast collection. The in-house library was challenged with two test sets of Malassezia strains, namely 165 reference strains from the CBS collection and 338 isolates collected in Greece, Italy, Sweden and Thailand. MALDI-TOF MS allowed correct identification of all 14 Malassezia spp. MALDI-TOF MS results were concordant with those of sequence analyses of the internal transcribed spacers (ITS1/ITS2) and the D1/D2 domains of the large subunit of the ribosomal DNA. Implementation of the MALDI-TOF MS system as a routine identification tool will contribute to correct identification of Malassezia yeasts with minimal effort and in a short turnaround time, which is especially important for the rapid identification of Malassezia in skin diseases and nosocomial outbreaks. © 2013 British Association of Dermatologists.

  18. Mechanism for odd-electron anion generation of dihydroxybenzoic acid isomers in matrix-assisted laser desorption/ionization mass spectrometry with density functional theory calculations.

    Science.gov (United States)

    Yamagaki, Tohru; Takeuchi, Michika; Watanabe, Takehiro; Sugahara, Kohtaro; Takeuchi, Takae

    2016-12-30

    Proton and radical are transferred between matrices and matrix and analyte in matrix-assisted laser desorption/ionization (MALDI) and these transfers drive ionization of analytes. The odd-electron anion [M-2H] •- was generated in dihydroxybenzoic acids (DHBs) and the ion abundance of the 2,5-DHB was the highest among six DHB isomers. We were interested in the mechanism of the ion generation of the odd-electron anion. The observed [M-2H] •- and [M-3H] - ions, which were generated with the hydrogen radical removed from the phenolic hydroxyl groups (OH) in DHB isomers, were analyzed using negative-ion MALDI-MS. The enthalpy for ion generation and their stable structures were calculated using the density functional theory (DFT) calculation program Gaussian 09 with the B3LYP functional and the 6-31+G(d) basis set. The number of observed [M-2H] •- and [M-3H] - ions of the DHB isomers was dependent on the positions of the phenolic OH groups in the DHB isomers because the carboxy group interacts with the ortho OH group due to neighboring group participation, as confirmed from the stable structures of the [M-2H] •- anions calculated with the Gaussian 09 program. The DHB isomers were placed into three categories according to the number of the ions. Odd-electron anions ([M-2H] •- ) and [M-2H • -H] - ([M-3H] - ) ions were generated from DHB isomers due to removal of the hydrogen radical from the phenolic groups. The enthalpy for ion generation revealed that ion formation proceeds via a two-step pathway through the [M-M] - ion as an intermediate. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd.

  19. Quantification of the PR-39 cathelicidin compound in porcine blood by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Smolira, Anna; Hałas, Stanisław; Wessely-Szponder, Joanna

    2015-10-15

    The PR-39 porcine cathelicidin occurs naturally in animal neutrophils. Its main function is antimicrobial activity, which potentially can be used in antibiotic treatments in veterinary medicine. Investigations concerning such a use require the detection and quantification of PR-39 in a given sample. The aim of this work is to determine the concentration of PR-39 contained in porcine blood. Prior to matrix-assisted laser desorption/ionization (MALDI) analysis, the porcine blood sample was subjected to crude extraction in order to release the active form of PR-39 from the neutrophil granules. Next, gel filtration chromatography was performed to separate PR-39 from other cathelicidins present in porcine blood. Positive ion MALDI time-of-flight (TOF) mass spectra of the resulting portion of lyophilisate with unknown PR-39 content were acquired in linear mode. To quantify PR-39 in the lyophilisate sample, the standard addition method was applied. The PR-39 concentration obtained in the lyophilisate sample was then converted into the peptide concentration in porcine blood. The linear fit function of the constructed calibration curve indicates an excellent correlation between the PR-39 peak intensity and the added quantity of synthetic PR-39 (R(2) = 0.994) and a low relative standard deviation of the slope = 1.98%. From the x-intercept of the straight line, we estimated the PR-39 concentration in porcine blood to be 20.5 ± 4.6 ng/mL. The MALDI method was successfully applied for the quantitative analysis of PR-39 found in porcine blood. Compared with other available methods, it is relatively easy, inexpensive and not time-consuming. Despite the method having lower accuracy than the enzyme-linked immunosorbent assay (ELISA), the results obtained here, by a much simpler method, are in good agreement with the literature data. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Rapid Screening of Epidemiologically Important Salmonella enterica subsp. enterica Serovars by Whole-Cell Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry ▿

    Science.gov (United States)

    Dieckmann, Ralf; Malorny, Burkhard

    2011-01-01

    Currently, 2,610 different Salmonella serovars have been described according to the White-Kauffmann-Le Minor scheme. They are routinely differentiated by serotyping, which is based on the antigenic variability at lipopolysaccharide moieties (O antigens), flagellar proteins (H1 and H2 antigens), and capsular polysaccharides (Vi antigens). The aim of this study was to evaluate the potential of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for rapid screening and identification of epidemiologically important Salmonella enterica subsp. enterica serovars based on specific sets of serovar-identifying biomarker ions. By analyzing 913 Salmonella enterica subsp. enterica strains representing 89 different serovars using MALDI-TOF mass spectrometry, several potentially serovar-identifying biomarker ions were selected. Based on a combination of genus-, species-, subspecies-, and serovar-identifying biomarker ions, a decision tree classification algorithm was derived for the rapid identification of the five most frequently isolated Salmonella enterica serovars, Enteritidis, Typhimurium/4,[5],12:i:-, Virchow, Infantis, and Hadar. Additionally, sets of potentially serovar-identifying biomarker ions were detected for other epidemiologically interesting serovars, such as Choleraesuis, Heidelberg, and Gallinarum. Furthermore, by using a bioinformatic approach, sequence variations corresponding to single or multiple amino acid exchanges in several biomarker proteins were tentatively assigned. The inclusivity and exclusivity of the specific sets of serovar-identifying biomarker ions for the top 5 serovars were almost 100%. This study shows that whole-cell MALDI-TOF mass spectrometry can be a rapid method for prescreening S. enterica subsp. enterica isolates to identify epidemiologically important serovars and to reduce sample numbers that have to be subsequently analyzed using conventional serotyping by slide agglutination techniques. PMID

  1. Application of Multiplex PCR Coupled with Matrix-Assisted Laser Desorption Ionization-Time of Flight Analysis for Simultaneous Detection of 21 Common Respiratory Viruses.

    Science.gov (United States)

    Zhang, Chi; Xiao, Yan; Du, Jiang; Ren, Lili; Wang, Jianwei; Peng, Junping; Jin, Qi

    2015-08-01

    Respiratory infections continue to pose a significant threat to human health. It is important to accurately and rapidly detect respiratory viruses. To compensate for the limits of current respiratory virus detection methods, we developed a 24-plex analysis (common respiratory virus-mass spectrometry [CRV-MS]) that can simultaneously detect and identify 21 common respiratory viruses based on a matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system. To evaluate the efficacy of the CRV-MS method, we used 102 samples that were confirmed positive for these common respiratory viruses. All tests using the CRV-MS method were effective, with no cross-reactivity observed with other common respiratory viruses. To confirm the usefulness of the CRV-MS method, we screened 336 nasal and throat swabs that were collected from adults or children with suspected viral acute respiratory tract infections using the CRV-MS method and consensus PCR/reverse transcription-PCR (RT-PCR) methods. Excluding four RNase P-negative samples, the CRV-MS and consensus PCR/RT-PCR methods detected respiratory viruses in 92.5% (307/332) and 89.5% (297/332) of the samples, respectively. The two methods yielded identical results for 306 (92.2%) samples, including negative results for 25 samples (7.5%) and positive results for 281 samples (84.6%). Differences between the two methods may reflect their different sensitivities. The CRV-MS method proved to be sensitive and robust, and it can be used in large-scale epidemiological studies of common respiratory virus infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  2. Matrix-assisted laser-desorption/ionization mass spectrometric imaging of olanzapine in a single hair using esculetin as a matrix.

    Science.gov (United States)

    Wang, Hang; Wang, Ying; Wang, Ge; Hong, Lizhi

    2017-07-15

    Matrix-assisted laser desorption/ionization-mass spectrometric imaging (MALDI-MSI) for the analysis of intact hair is a powerful tool for monitoring changes in drug consumption. The embedding of a low drug concentration in the hydrophobic hair matrix makes it difficult to extract and detect, and requires an improved method to increase detection sensitivity. In this study, an MSI method using MALDI-Fourier transform ion cyclotron resonance was developed for direct identification and imaging of olanzapine in hair samples using the positive ion mode. Following decontamination, scalp hair samples from an olanzapine user were scraped from the proximal to the distal end three times, and 5mm hair sections were fixed onto an Indium-Tin-Oxide (ITO)-coated microscopic glass slide. Esculetin (6,7-dihydroxy-2H-chromen-2-one) was used as a new hydrophobic matrix to increase the affinity, extraction and ionization efficiency of olanzapine in the hair samples. The spatial distribution of olanzapine was observed using five single hairs from the same drug user. This matrix improves the affinity of olanzapine in hair for molecular imaging with mass spectrometry. This method may provide a detection power for olanzapine to the nanogram level per 5mm hair. Time course changes in the MSI results were also compared with quantitative HPLC-MS/MS for each 5mm segment of single hair shafts selected from the MALDI target. MALDI imaging intensities in single hairs showed good semi-quantitative correlation with the results from conventional HPLC-MS/MS. MALDI-MSI is suitable for monitoring drug intake with a high time resolution. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Organic salt NEDC (N-naphthylethylenediamine dihydrochloride) assisted laser desorption ionization mass spectrometry for identification of metal ions in real samples.

    Science.gov (United States)

    Hou, Jian; Chen, Suming; Zhang, Ning; Liu, Huihui; Wang, Jianing; He, Qing; Wang, Jiyun; Xiong, Shaoxiang; Nie, Zongxiu

    2014-07-07

    The significance of metals in life and their epidemiological effects necessitate the development of a direct, efficient, and rapid method of analysis. The matrix assisted laser desorption/ionization technique is on the horns of a dilemma of metal analysis as the conventional matrixes have high background in the low mass range. An organic salt, NEDC (N-naphthylethylenediamine dihydrochloride), is applied as a matrix for identification of metal ions in the negative ion mode in the present work. Sixteen metal ions, Ba(2+), Ca(2+), Cd(2+), Ce(3+), Co(2+), Cu(2+), Fe(3+), Hg(2+), K(+), Mg(2+), Mn(2+), Na(+), Ni(2+), Pb(2+), Sn(2+) and Zn(2+), in the form of their chloride-adducted clusters were systematically tested. Mass spectra can provide unambiguous identification through accurate mass-to-charge ratios and characteristic isotope patterns. Compared to ruthenium ICP standard solution, tris(2,2'-bipyridyl)dichlororuthenium(ii) (C30H24N6Cl2Ru) can form organometallic chloride adducts to discriminate from the inorganic ruthenium by this method. After evaluating the sensitivity for Ca, Cu, Mg, Mn, Pb and Zn and plotting their quantitation curves of signal intensity versus concentration, we determined magnesium concentration in lake water quantitatively to be 5.42 mg L(-1) using the standard addition method. There is no significant difference from the result obtained with ICP-OES, 5.8 mg L(-1). Human urine and blood were also detected to ascertain the multi-metal analysis ability of this strategy in complex samples. At last, we explored its applicability to tissue slice and visualized sodium and potassium distribution by mass spectrometry imaging in the normal Kunming mouse brain.

  4. The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for rapid bacterial identification in patients with smear-positive bacterial meningitis.

    Science.gov (United States)

    Bishop, B; Geffen, Y; Plaut, A; Kassis, O; Bitterman, R; Paul, M; Neuberger, A

    2018-02-01

    To assess the potential of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in rapid identification of bacteria from smear-positive cerebrospinal fluid (CSF) in a cohort of patients with meningitis. Single-centre observational study, including adults and children with community-acquired or postneurosurgical bacterial meningitis. Meningitis was defined using established criteria. Samples of CSF that had a positive CSF Gram stain were directly examined by MALDI-TOF-MS. Identification was considered accurate when identical to the CSF culture or PCR results (species and genus level). Laboratory workers performing the MALDI-TOF-MS and interpreting its results were blinded to the direct smear results, except for the fact that it was positive. MALDI-TOF-MS results were not conveyed to clinicians. MALDI-TOF-MS was tested on 44 CSF samples; ten samples were obtained from patients with community-acquired meningitis, and 34 samples were from patients with postneurosurgical meningitis. The assay identified bacteria correctly in 17/21 of the samples with Gram-negative rods observed on the direct smear, all obtained from patients who had undergone neurosurgery, (sensitivity 81%, 95% CI 64.2%-97.7%). In the postneurosurgical group, Gram-positive cocci were identified correctly in only 1/11 (9.1%) of the samples, and Candida species were not identified in two samples. Among patients with community-acquired meningitis, the assay did not identify Streptococcus pneumoniae in eight of eight samples, Neisseria meningitidis in one sample (1/1), and Streptococcus agalactiae in one sample (1/1). We found MALDI-TOF-MS to be useful in the rapid identification of Gram-negative rods directly from smear-positive CSF samples, but not of Gram-positive bacteria. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  5. Rapid Detection and Identification of Candidemia by Direct Blood Culturing on Solid Medium by Use of Lysis-Centrifugation Method Combined with Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Idelevich, Evgeny A; Grünastel, Barbara; Becker, Karsten

    2017-01-01

    Candida sepsis is a life-threatening condition with increasing prevalence. In this study, direct blood culturing on solid medium using a lysis-centrifugation procedure enabled successful Candida species identification by matrix-assisted laser desorption-ionization time of flight mass spectrometry on average 3.8 h (Sabouraud agar) or 7.4 h (chocolate agar) before the positivity signal for control samples in Bactec mycosis-IC/F or Bactec Plus aerobic/F bottles, respectively. Direct culturing on solid medium accelerated candidemia diagnostics compared to that with automated broth-based systems. Copyright © 2016 American Society for Microbiology.

  6. Identification of bovine-associated coagulase-negative staphylococci by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using a direct transfer protocol.

    Science.gov (United States)

    Cameron, M; Barkema, H W; De Buck, J; De Vliegher, S; Chaffer, M; Lewis, J; Keefe, G P

    2017-03-01

    This study evaluated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) for the identification of bovine-associated coagulase-negative staphylococci (CNS), a heterogeneous group of different species. Additionally, we aimed to expand the MALDI-ToF MS database with new reference spectra as required to fill the gaps within the existing commercial spectral library. A total of 258 isolates of CNS were used in the study, covering 16 different CNS species. The majority of the isolates were previously identified by rpoB gene sequencing (n = 219), and the remainder were identified by sequencing of 16S rRNA, hsp60, or both rpoB and hsp60. The genotypic identification was considered the gold standard identification. All MALDI-ToF MS identifications were carried out using the direct transfer method. In a preliminary evaluation (n = 32 isolates; 2 of each species) with the existing commercial database, MALDI-ToF MS showed a typeability of 81% (26/32) and an accuracy of 96% (25/26). In the main evaluation (n = 226 isolates), MALDI-ToF MS with the existing commercial Biotyper (Bruker Daltonics Inc., Billerica, MA) database achieved a typeability of 92.0% (208/226) and an accuracy of 99.5% (207/208). Based on the assessment of the existing commercial database and prior knowledge of the species, a total of 13 custom reference spectra, covering 8 species, were created and added to the commercial database. Using the custom reference spectra expanded database, isolates were identified by MALDI-ToF MS with 100% typeability and 100% accuracy. Whereas the MALDI-ToF MS manufacturer's cutoff for species-level identification is 2.000, the reduction of the species level cutpoint to ≥1.700 improved the species-level identification rates (from 64 to 92% for the existing commercial database) when classifying CNS isolates. Overall, MALDI-ToF MS using the direct transfer method was shown to be a highly reliable tool for the identification of bovine

  7. Detection of AmpC β-lactamase-producing Gram-negative bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Li, C; Ding, S; Huang, Y; Wang, Z; Shen, J; Ling, H; Xu, Y

    2017-11-22

    Rapid detection of AmpC-producing strains of Gram-negative bacteria is beneficial for patient care. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a novel method that has demonstrated the resistance of a strain to β-lactam antibiotics by determining the molecular structure of an antibiotic and its degradation products. To study the detection of AmpC-producing Gram-negative bacteria by MALDI-TOF MS and to determine whether the method can be used in clinical practice. A total of 105 strains were detected by determining their phenotypes and sequence analysis. Sixty-nine well-characterized AmpC-producing and 36 non-AmpC-producing strains were studied. The bacteria were incubated in different reaction buffer solutions (10 mM NH 4 HCO 3 /0.005% sodium dodecyl sulphate at pH 8.0) containing cefotaxime (0.50 mg/mL), ceftazidime (0.25 mg/mL), ceftriaxone (0.50 mg/mL), cefepime (0.50 mg/mL), and cefoxitin (0.25 and 0.50 mg/mL), respectively. The mixture was centrifuged at 13,000 g for 2 min, and the supernatant analysed by MALDI-TOF MS after incubation for 30, 60, 90, 120, and 240 min. Antibiotic hydrolysed and decarboxylated peaks were identified. When incubated for 90 min, hydrolysed cefotaxime formed peaks at 434 and 494 Da, and the sensitivity and specificity for detection of AmpC-producing strains were 85.5% (59/69) and 88.9% (32/36). When incubated for 4 h, hydrolysed ceftazidime formed peaks at 563 and 587 Da, and the sensitivity and specificity were 89.9% (62/69) and 94.5% (34/36), respectively. For hydrolysed ceftriaxone (0.5 mg/mL), cefepime (0.5 mg/mL) and two concentrations of cefoxitin (0.25 and 0.5 mg/mL), no peaks amenable to analysis were identified. This study demonstrated that MALDI-TOF MS can rapidly detect AmpC-producing strains. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Nocardia, Rhodococcus, Kocuria, Gordonia, Tsukamurella, and Listeria Species

    Science.gov (United States)

    Lee, Tai-Fen; Du, Shin-Hei; Teng, Shih-Hua; Liao, Chun-Hsing; Sheng, Wang-Hui; Teng, Lee-Jene

    2014-01-01

    We evaluated whether the Bruker Biotyper matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system provides accurate species-level identifications of 147 isolates of aerobically growing Gram-positive rods (GPRs). The bacterial isolates included Nocardia (n = 74), Listeria (n = 39), Kocuria (n = 15), Rhodococcus (n = 10), Gordonia (n = 7), and Tsukamurella (n = 2) species, which had all been identified by conventional methods, molecular methods, or both. In total, 89.7% of Listeria monocytogenes, 80% of Rhodococcus species, 26.7% of Kocuria species, and 14.9% of Nocardia species (n = 11, all N. nova and N. otitidiscaviarum) were correctly identified to the species level (score values, ≥2.0). A clustering analysis of spectra generated by the Bruker Biotyper identified six clusters of Nocardia species, i.e., cluster 1 (N. cyriacigeorgica), cluster 2 (N. brasiliensis), cluster 3 (N. farcinica), cluster 4 (N. puris), cluster 5 (N. asiatica), and cluster 6 (N. beijingensis), based on the six peaks generated by ClinProTools with the genetic algorithm, i.e., m/z 2,774.477 (cluster 1), m/z 5,389.792 (cluster 2), m/z 6,505.720 (cluster 3), m/z 5,428.795 (cluster 4), m/z 6,525.326 (cluster 5), and m/z 16,085.216 (cluster 6). Two clusters of L. monocytogenes spectra were also found according to the five peaks, i.e., m/z 5,594.85, m/z 6,184.39, and m/z 11,187.31, for cluster 1 (serotype 1/2a) and m/z 5,601.21 and m/z 11,199.33 for cluster 2 (serotypes 1/2b and 4b). The Bruker Biotyper system was unable to accurately identify Nocardia (except for N. nova and N. otitidiscaviarum), Tsukamurella, or Gordonia species. Continuous expansion of the MALDI-TOF MS databases to include more GPRs is necessary. PMID:24759706

  9. Selective reduction of C=C double bonds in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of microcystins.

    Science.gov (United States)

    Deleuze, Christelle; De Pauw, Edwin; Quinton, Loic

    2010-01-01

    Cyanobacteria are photosynthetic bacteria encountered in various aquatic environments. Some of them are able to produce powerful toxins called cyanotoxins. Among cyanotoxins, microcystins (MCs) constitute a group of closely related cyclic heptapeptides. Their sequences are made up of classical amino acids as well as post- translational modified ones. Interestingly, in vivo metabolism of microcystins seems to be greatly dependent on various minor structural differences and particularly those of the seventh amino acid, which can be either dehydroalanine (or a derivative), dehydroaminobutyric acid (or a derivative), serine or alanine. As a consequence, microcystins have been classified on the basis of the nature of this singular amino acid. A major difficulty in the classification of such toxins is that some of them share the same molecular masses and the same molecular formulas. Consequently, a simple mass measurement is not sufficient to determine the structure and the class of a toxin of interest. Heavy and expensive techniques are used to classify them, such as multi-dimensional nuclear magnetic resonance and amino acid analysis. In this work, a new matrix-assisted laser desorption/ionization time-of-flight method leading to an easy classification of MCs is proposed. The methodology relies on the reductive properties of the matrix 1,5-diaminonaphtalene (1,5-DAN) which appears to be able to selectively reduce the double carbon-carbon bond belonging to the seventh amino acid. Moreover, the yield of reduction seems to be influenced by the degree of substitution of this double bond, allowing a discrimination between dehydroalanine and dehydroaminobutyric acid. This selective reduction was confirmed by the study of three synthetic peptides by mass spectrometry and tandem mass spectrometry. According to these results, the use of reductive matrices seems to be promising in the study of microcystins and in their classification. More generally, 1,5-DAN allows the selective

  10. Direct detection of carbapenemase-associated proteins of Acinetobacter baumannii using nanodiamonds coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Chang, Kai-Chih; Chung, Chin-Yi; Yeh, Chen-Hsing; Hsu, Kuo-Hsiu; Chin, Ya-Ching; Huang, Sin-Siang; Liu, Bo-Rong; Chen, Hsi-An; Hu, Anren; Soo, Po-Chi; Peng, Wen-Ping

    2018-04-01

    The appearance and spread of carbapenem-resistant Acinetobacter baumannii (CRAB) pose a challenge for optimization of antibiotic therapies and outbreak preventions. The carbapenemase production can be detected through culture-based methods (e.g. Modified Hodge Test-MHT) and DNA based methods (e.g. Polymerase Chain Reaction-PCR). The culture-based methods are time-consuming, whereas those of PCR assays need only a few hours but due to its specificity, can only detect known genetic targets encoding carbapenem-resistance genes. Therefore, new approaches to detect carbapenemase-producing A. baumannii are of great importance. Here, we have developed a rapid and novel method using detonation nanodiamonds (DNDs) as a platform for concentration and extraction of A. baumannii carbapenemase-associated proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS) analysis. To concentrate and extract the A. baumannii carbapenemase-associated proteins, we tested several protein precipitation conditions and found a 0.5% trifluoroacetic acid (TFA) solution within the bacterial suspension could result in strong ion signals with DNDs. A total of 66 A. baumannii clinical-isolates including 51 carbapenem-resistant strains and 15 carbapenem-susceptible strains were tested. Our result showed that among the 51 carbapenem-resistant strains 49 strains had a signal at m/z ~40,279 (±87); among the 15 carbapenem-susceptible strains, 4 strains showed a signal at m/z ~40,279. With on-diamond digestion, we confirmed that the captured protein at m/z ~40,279 was related to ADC family extended-spectrum class C beta-lactamase, from A. baumannii. Using this ADC family protein as a biomarker (m/z ~ 40,279) for carbapenem susceptibility testing of A. baumannii, the sensitivity and the specificity could reach 96% and 73% as compared to traditional imipenem susceptibility testing (MIC results). However, the sensitivity and specificity of this method

  11. Teaching Microbial Identification with Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS and Bioinformatics Tools

    Directory of Open Access Journals (Sweden)

    Wenfa Ng

    2013-01-01

    Full Text Available Ever since the first observation of “animalcules” under a microscope, and the subsequent discovery of microorganisms of myriad size, shape, pigmentation and motility modes, classification in aid of microbial identification is key to understanding inter-relationships between diverse microbes. Combining universal applicability with robustness, 16S rRNA sequencing is the gold standard for microbial typing; however, recent developments in clinical diagnostics have called attention to a shift towards PCR-independent instrumentation and methods given PCR’s requirement for expensive and complex sample preparation. Using ribosomal proteins as biomarkers for evolutionary relatedness, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS - originally developed for the soft ionization of proteins and peptides in proteomics studies - has been successfully applied to identifying bacteria, archaea, fungi and viruses to the species, and, on occasions, sub-species level. Though experimentally proven and increasingly adopted in the clinic, the relatively low-cost (on a per sample basis and rapid MALDI-TOF MS microbial identification technique, along with its theoretical principles and methodology, is a conspicuous absentee in contemporary microbiology curricula. Motivated by a desire to close the curriculum gap, this article describes a discovery-based activity for teaching microbial identification - using MALDI-TOF MS in combination with open-source genomics and proteomics search tools – while providing tips on mass spectra interpretation and activity implementation for lowering the barrier for classroom adoption. Infused with inquiry-based learning concepts guiding students in identifying microbes from environmental water samples with unknown species diversity, the activity spurs students’ learning by igniting their spirit of inquiry, which leads to better mastery of concepts; a significant departure from

  12. Matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry as a reliable proteomic method for characterization of Escherichia coli and Salmonella isolates.

    Science.gov (United States)

    Shell, Waleed S; Sayed, Mahmoud Lotfy; Allah, Fatma Mohamed Gad; Gamal, Fatma Elzahraa Mohamed; Khder, Afaf Ahmed; Samy, A A; Ali, Abdel Hakam M

    2017-09-01

    Identification of pathogenic clinical bacterial isolates is mainly dependent on phenotypic and genotypic characteristics of the microorganisms. These conventional methods are costive, time-consuming, and need special skills and training. An alternative, mass spectral (proteomics) analysis method for identification of clinical bacterial isolates has been recognized as a rapid, reliable, and economical method for identification. This study was aimed to evaluate and compare the performance, sensitivity and reliability of traditional bacteriology, phenotypic methods and matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry (MALDI-TOF MS) in the identification of clinical Escherichia coli and Salmonella isolates recovered from chickens. A total of 110 samples (cloacal, liver, spleen, and/or gall bladder) were collected from apparently healthy and diseased chickens showing clinical signs as white chalky diarrhea, pasty vent, and decrease egg production as well as freshly dead chickens which showing postmortem lesions as enlarged liver with congestion and enlarged gall bladder from different poultry farms. Depending on colonial characteristics and morphological characteristics, E. coli and Salmonella isolates were recovered and detected in only 42 and 35 samples, respectively. Biochemical identification using API 20E identification system revealed that the suspected E. coli isolates were 33 out of 42 of colonial and morphological identified E. coli isolates where Salmonella isolates were represented by 26 out of 35 of colonial and morphological identified Salmonella isolates. Serological identification of isolates revealed that the most predominant E. coli serotypes were O1 and O78 while the most predominant Salmonella serotype of Salmonella was Salmonella Pullorum. All E. coli and Salmonella isolates were examined using MALDI-TOF MS. In agreement with traditional identification, MADI-TOF MS identified all clinical bacterial samples with valid

  13. Bruker biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Nocardia, Rhodococcus, Kocuria, Gordonia, Tsukamurella, and Listeria species.

    Science.gov (United States)

    Hsueh, Po-Ren; Lee, Tai-Fen; Du, Shin-Hei; Teng, Shih-Hua; Liao, Chun-Hsing; Sheng, Wang-Hui; Teng, Lee-Jene

    2014-07-01

    We evaluated whether the Bruker Biotyper matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system provides accurate species-level identifications of 147 isolates of aerobically growing Gram-positive rods (GPRs). The bacterial isolates included Nocardia (n = 74), Listeria (n = 39), Kocuria (n = 15), Rhodococcus (n = 10), Gordonia (n = 7), and Tsukamurella (n = 2) species, which had all been identified by conventional methods, molecular methods, or both. In total, 89.7% of Listeria monocytogenes, 80% of Rhodococcus species, 26.7% of Kocuria species, and 14.9% of Nocardia species (n = 11, all N. nova and N. otitidiscaviarum) were correctly identified to the species level (score values, ≥ 2.0). A clustering analysis of spectra generated by the Bruker Biotyper identified six clusters of Nocardia species, i.e., cluster 1 (N. cyriacigeorgica), cluster 2 (N. brasiliensis), cluster 3 (N. farcinica), cluster 4 (N. puris), cluster 5 (N. asiatica), and cluster 6 (N. beijingensis), based on the six peaks generated by ClinProTools with the genetic algorithm, i.e., m/z 2,774.477 (cluster 1), m/z 5,389.792 (cluster 2), m/z 6,505.720 (cluster 3), m/z 5,428.795 (cluster 4), m/z 6,525.326 (cluster 5), and m/z 16,085.216 (cluster 6). Two clusters of L. monocytogenes spectra were also found according to the five peaks, i.e., m/z 5,594.85, m/z 6,184.39, and m/z 11,187.31, for cluster 1 (serotype 1/2a) and m/z 5,601.21 and m/z 11,199.33 for cluster 2 (serotypes 1/2b and 4b). The Bruker Biotyper system was unable to accurately identify Nocardia (except for N. nova and N. otitidiscaviarum), Tsukamurella, or Gordonia species. Continuous expansion of the MALDI-TOF MS databases to include more GPRs is necessary. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  14. Analyses of the in vitro non-enzymatic glycation of peptides/proteins by matrix-assisted laser desorption/ionization mass spectrometry

    Science.gov (United States)

    Lee, Bao-Shiang; Krishnanchettiar, Sangeeth; Lateef, Syed Salman; Gupta, Shalini

    2007-01-01

    Non-enzymatic glycation of proteins with the reducing agent glucose is implicated to be responsible for diabetes-derived complications, food browning, and aging. However, the non-enzymatic glycation process of peptides/proteins is not well understood and further research is needed to gain an understanding of the underlying principles involved in diabetes-related complications. In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is used to analyze the in vitro glycation of peptides/proteins. In addition to the physiological conditions, harsh conditions (higher concentration of glucose, higher or lower pH, and higher temperature) are also used in this study. Peptides/proteins are reacted with glucose for up to 120 h at 4 [degree sign]C, 37 [degree sign]C, or 65 [degree sign]C. Single and/or multiple glycations are observed using broad pH conditions (from 10% TFA with pKa of 0.5 to pH 10) at various glucose concentrations (from 0.01 M to 1 M). Data suggest that glucose reacts readily with both peptides and proteins, and the efficiency of the glycation increases with higher temperature, higher pH, higher glucose concentration, or longer incubation time. However, influence of the buffer pH on the efficiency of the glycation of peptides is less pronounced compared to that of proteins. This effect could result from denaturation of proteins at higher pH and the resultant exposure of potential glycation sites. This data could lead to the inference that the glycation process of peptides/proteins would occur but proceed very slowly under the diabetes conditions in vivo (37 [degree sign]C, ~neutral pH, ~0.007 M glucose). Postsource decay and MS/MS results of singly glycated angiotensin I, P14R (PPPPPPPPPPPPPPR), and human adrenocorticotropic hormone (ATCH) fragments 1-13 indicate that glucose reacts with the amino group of the N-terminal of ATCH 1-13 and the guanidino group of the arginine residue of both angiotensin I and P14R.

  15. Detection of Hanganutziu-Deicher antigens in O-glycans from pig heart tissues by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Jeong, Hee-Jin; Adhya, Mausumi; Park, Hae-Min; Kim, Yun-Gon; Kim, Byung-Gee

    2013-01-01

    In the α1,3-galactosyltransferase knockout (α-GalT KO) pig era, identification of the non-Gal epitopes is necessary for successful pig-to-human xenotransplantation. Recently, we successfully detected α-Gal epitopes as well as Hanganutziu-Deicher (H-D) antigens from the N-glycans in the pig heart tissues, which have been considered as promising non-Gal antigens. However, the profiling of O-glycan from pig heart tissues had not been performed owing to the difficulty of O-glycan preparation. In this study, we established the simple and sensitive method to profile O-glycans from pig heart aortic valve, aortic wall, pulmonary valve, pulmonary wall, and cardiac muscle tissues. To liberate O-glycans from the pig heart tissues, we used non-reductive β-elimination reagent and subsequently purified the glycans. After permethylation, the glycans were qualitatively analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The comprehensive O-glycan analysis method was successfully validated using model glycoproteins such as bovine serum fetuin (BSF) and bovine submaxillary gland mucin (BSM) glycoproteins, and their O-glycan profiles were in accordance with the data of previous studies. Next, we applied the method for O-glycan release and characterization to analysis of various pig heart tissues. As a result, total 39, 33, 24, 36, and 25 of O-glycans were detected from aortic valve, aortic wall, pulmonary valve, pulmonary wall, and cardiac muscle, respectively. Furthermore, four in aortic valve, one in aortic wall, one in pulmonary valve, one in pulmonary wall, and one in cardiac muscle were particularly determined as terminally N-glycolylneuraminic acid-linked O-glycans, which is considered to be the H-D antigens. Here, we initially described the O-glycan structures of various pig heart tissues, and additionally, the existence of H-D antigen type O-glycans was firstly identified. These results will be fundamental information

  16. Modified-Atmospheric Pressure-Matrix Assisted Laser Desorption/Ionization Identification of Friction Modifier Additives Oleamide and Ethoxylated Tallow Amines on Varied Metal Target Materials and Tribologically Stressed Steel Surfaces.

    Science.gov (United States)

    Widder, Lukas; Ristic, Andjelka; Brenner, Florian; Brenner, Josef; Hutter, Herbert

    2015-11-17

    For many tasks in failure and damage analysis of surfaces deteriorated in heavy tribological contact, the detailed characterization of used lubricants and their additives is essential. The objective of the presented work is to establish accessibility of tribostressed surfaces for direct characterization via modified atmospheric pressure-matrix assisted laser desorption/ionization-mass spectrometry (m-AP-MALDI-MS). Special target holders were constructed to allow target samples of differing shape and form to fit into the desorption/ionization chamber. The best results of desorption and ionization on different target materials and varying roughnesses were achieved on smooth surfaces with low matrix/substrate interaction. M-AP-MALDI characterization of tribologically stressed steel surfaces after pin-on-disc sliding wear tests (SRV-tribotests) yielded positive identification of used friction modifier additives. Further structure elucidation by electrospray ionization mass spectrometry (ESI-MS) and measurements of worn surfaces by time-of-flight-secondary ion mass spectrometry (TOF-SIMS) accompanied findings about additive behavior and deterioration during tribological contact. Using m-AP-MALDI for direct offline examinations of worn surfaces may set up a quick method for determination of additives used for lubrication and general characterization of a tribological system.

  17. Plasmonic nanostructures for surface enhanced spectroscopic methods.

    Science.gov (United States)

    Jahn, Martin; Patze, Sophie; Hidi, Izabella J; Knipper, Richard; Radu, Andreea I; Mühlig, Anna; Yüksel, Sezin; Peksa, Vlastimil; Weber, Karina; Mayerhöfer, Thomas; Cialla-May, Dana; Popp, Jürgen

    2016-02-07

    A comprehensive review of theoretical approaches to simulate plasmonic-active metallic nano-arrangements is given. Further, various fabrication methods based on bottom-up, self-organization and top-down techniques are introduced. Here, analytical approaches are discussed to investigate the optical properties of isotropic and non-magnetic spherical or spheroidal particles. Furthermore, numerical methods are introduced to research complex shaped structures. A huge variety of fabrication methods are reviewed, e.g. bottom-up preparation strategies for plasmonic nanostructures to generate metal colloids and core-shell particles as well as complex-shaped structures, self-organization as well as template-based methods and finally, top-down processes, e.g. electron beam lithography and its variants as well as nanoimprinting. The review article is aimed at beginners in the field of surface enhanced spectroscopy (SES) techniques and readers who have a general interest in theoretical modelling of plasmonic substrates for SES applications as well as in the fabrication of the desired structures based on methods of the current state of the art.

  18. MoS2/Ag nanohybrid: A novel matrix with synergistic effect for small molecule drugs analysis by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Zhao, Yaju; Deng, Guoqing; Liu, Xiaohui; Sun, Liang; Li, Hui; Cheng, Quan; Xi, Kai; Xu, Danke

    2016-01-01

    This paper reports a facile synthesis of molybdenum disulfide nanosheets/silver nanoparticles (MoS 2 /Ag) hybrid and its use as an effective matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The nanohybrid exerts a strong synergistic effect, leading to high performance detection of small molecule analytes including amino acids, peptides, fatty acids and drugs. The enhancement of laser desorption/ionization (LDI) efficiency is largely attributed to the high surface roughness and large surface area for analyte adsorption, better dispersibility, increased thermal conductivity and enhanced UV energy absorption as compared to pure MoS 2 . Moreover, both Ag nanoparticles and the edge of the MoS 2 layers function as deprotonation sites for proton capture, facilitating the charging process in negative ion mode and promoting formation of negative ions. As a result, the MoS 2 /Ag nanohybrid proves to be a highly attractive matrix in MALDI-TOF MS, with desired features such as high desorption/ionization efficiency, low fragmentation interference, high salt tolerance, and no sweet-spots for mass signal. These characteristic properties allowed for simultaneous analysis of eight different drugs and quantification of acetylsalicylic acid in the spiked human serum. This work demonstrates for the first time the fabrication and application of a novel MoS 2 /Ag hybrid, and provides a new platform for use in the rapid and high throughput analysis of small molecules by mass spectrometry. - Highlights: • MoS 2 /Ag nanohybrid was applied as a novel matrix in negative-ion MALDI-TOF MS. • The MoS 2 /Ag nanohybrid exerted synergistic effect on the detection of small molecules. • The MoS 2 /Ag nanohybrid showed good signal reproducibility and low background interferences comparing to organic matrices. • MoS 2 /Ag allows simultaneous analysis of multiple drugs and quantification of acetylsalicylic acid in spiked serum

  19. MoS2/Ag nanohybrid: A novel matrix with synergistic effect for small molecule drugs analysis by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Zhao, Yaju; Deng, Guoqing; Liu, Xiaohui; Sun, Liang; Li, Hui; Cheng, Quan; Xi, Kai; Xu, Danke

    2016-09-21

    This paper reports a facile synthesis of molybdenum disulfide nanosheets/silver nanoparticles (MoS2/Ag) hybrid and its use as an effective matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The nanohybrid exerts a strong synergistic effect, leading to high performance detection of small molecule analytes including amino acids, peptides, fatty acids and drugs. The enhancement of laser desorption/ionization (LDI) efficiency is largely attributed to the high surface roughness and large surface area for analyte adsorption, better dispersibility, increased thermal conductivity and enhanced UV energy absorption as compared to pure MoS2. Moreover, both Ag nanoparticles and the edge of the MoS2 layers function as deprotonation sites for proton capture, facilitating the charging process in negative ion mode and promoting formation of negative ions. As a result, the MoS2/Ag nanohybrid proves to be a highly attractive matrix in MALDI-TOF MS, with desired features such as high desorption/ionization efficiency, low fragmentation interference, high salt tolerance, and no sweet-spots for mass signal. These characteristic properties allowed for simultaneous analysis of eight different drugs and quantification of acetylsalicylic acid in the spiked human serum. This work demonstrates for the first time the fabrication and application of a novel MoS2/Ag hybrid, and provides a new platform for use in the rapid and high throughput analysis of small molecules by mass spectrometry. Copyright © 2016. Published by Elsevier B.V.

  20. A SIMPLE AND RAPID MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY METHOD TO SCREEN FISH PLASMA SAMPLES FOR ESTROGEN-RESPONSIVE BIOMARKERS

    Science.gov (United States)

    In this study, we describe and evaluate the performance of a simple and rapid mass spectral method for screening fish plasma for estrogen-responsive biomarkers using matrix assisted laster desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) couopled with a short...

  1. CuFe2O4 magnetic nanocrystal clusters as a matrix for the analysis of small molecules by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Lin, Zian; Zheng, Jiangnan; Bian, Wei; Cai, Zongwei

    2015-08-07

    CuFe2O4 magnetic nanocrystal clusters (CuFe2O4 MNCs) were proposed as a new matrix for small molecule analysis by negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the first time. We demonstrated its advantages over conventional organic matrices in the detection of small molecules such as amino acids, peptides, nucleobases, fatty acids, and steroid hormones. A systematic comparison of CuFe2O4 MNCs with different ionization modes revealed that MS spectra obtained for the CuFe2O4 MNC matrix in the negative ion mode was only featured by deprotonated ion peaks with a free matrix background, which was different from the complicated alkali metal adducts produced in the positive ion mode. The developed method was found relatively tolerant to salt contamination and exhibited good reproducibility. A detection limit down to the subpicomolar level was achieved when testosterone was analyzed. In addition, by comparison of the MS spectra obtained from bare Fe3O4 and MFe2O4 MNC (M = Co, Ni, Cu, Zn) matrices, two main factors of MFe2O4 MNC matrices were revealed to play a vital role in assisting the negative ion desorption/ionization (D/I) process: doping transition metals into ferrite nanocrystals favoring laser absorption and energy transfer and a good match between the UV absorption of MFe2O4 MNCs and the excitation of nitrogen laser source facilitating LDI efficiency. This work creates a new branch of application for MFe2O4 MNCs and provides an alternative solution for small molecule analysis.

  2. Surface-enhanced FAST CARS: en route to quantum nano-biophotonics

    Science.gov (United States)

    Voronine, Dmitri V.; Zhang, Zhenrong; Sokolov, Alexei V.; Scully, Marlan O.

    2018-02-01

    Quantum nano-biophotonics as the science of nanoscale light-matter interactions in biological systems requires developing new spectroscopic tools for addressing the challenges of detecting and disentangling weak congested optical signals. Nanoscale bio-imaging addresses the challenge of the detection of weak resonant signals from a few target biomolecules in the presence of the nonresonant background from many undesired molecules. In addition, the imaging must be performed rapidly to capture the dynamics of biological processes in living cells and tissues. Label-free non-invasive spectroscopic techniques are required to minimize the external perturbation effects on biological systems. Various approaches were developed to satisfy these requirements by increasing the selectivity and sensitivity of biomolecular detection. Coherent anti-Stokes Raman scattering (CARS) and surface-enhanced Raman scattering (SERS) spectroscopies provide many orders of magnitude enhancement of chemically specific Raman signals. Femtosecond adaptive spectroscopic techniques for CARS (FAST CARS) were developed to suppress the nonresonant background and optimize the efficiency of the coherent optical signals. This perspective focuses on the application of these techniques to nanoscale bio-imaging, discussing their advantages and limitations as well as the promising opportunities and challenges of the combined coherence and surface enhancements in surface-enhanced coherent anti-Stokes Raman scattering (SECARS) and tip-enhanced coherent anti-Stokes Raman scattering (TECARS) and the corresponding surface-enhanced FAST CARS techniques. Laser pulse shaping of near-field excitations plays an important role in achieving these goals and increasing the signal enhancement.

  3. Desorption in Mass Spectrometry.

    Science.gov (United States)

    Usmanov, Dilshadbek Tursunbayevich; Ninomiya, Satoshi; Chen, Lee Chuin; Saha, Subhrakanti; Mandal, Mridul Kanti; Sakai, Yuji; Takaishi, Rio; Habib, Ahsan; Hiraoka, Kenzo; Yoshimura, Kentaro; Takeda, Sen; Wada, Hiroshi; Nonami, Hiroshi

    2017-01-01

    In mass spectrometry, analytes must be released in the gas phase. There are two representative methods for the gasification of the condensed samples, i.e. , ablation and desorption. While ablation is based on the explosion induced by the energy accumulated in the condensed matrix, desorption is a single molecular process taking place on the surface. In this paper, desorption methods for mass spectrometry developed in our laboratory: flash heating/rapid cooling, Leidenfrost phenomenon-assisted thermal desorption (LPTD), solid/solid friction, liquid/solid friction, electrospray droplet impact (EDI) ionization/desorption, and probe electrospray ionization (PESI), will be described. All the methods are concerned with the surface and interface phenomena. The concept of how to desorb less-volatility compounds from the surface will be discussed.

  4. [The investigation of humic acid by surface-enhanced Raman spectroscopy].

    Science.gov (United States)

    Zhang, Wen-Juan; Li, Ying; Guo, Jin-Jia; Xiao, Qiong; Yu, Li

    2013-05-01

    Humic acid (HA), which are organic compounds widely existing in the oceans, rivers and soil, has important significance for the environmental monitoring of soil and water. In this paper, ai ming at the problem of Surface-enhanced Raman Spectroscopy (SERS) applying for HA detection in water, the characteristics of the humic acid on silver colloids was studied by means of SERS. The influence of laser irradiation time, HA concentrations and pH value on the surface-enhanced effects of HA were investigated. The experimental results show that the SERS spectra of HA is ideal when the laser irradiation time between 20-30 min. The SERS of different HA concentrations was detected. It was found that the relative intensity at 1 379 cm(-1) increased as a linear function of the concentration of HA with correlation coefficient R2 of 0.993. The SERS of HA was found to be very sensitive to pH, the SERS spectra of HA was very weak at neutral pH, but at acidic pH and alkaline pH a remarkable increase of SERS intensity occurred. The SERS of HA in running water was detected too. The experimental results show that it is feasible to detect HA in natural water by means of surface-enhanced Raman spectroscopy.

  5. Application of Matrix-assisted Laser Desorption Ionization Time-of-flight Mass Spectrometry for Identification of Coagulase-negative Staphylococci Isolated from Milk of Cows with Subclinical Mastitis.

    Science.gov (United States)

    Banach, T; Bochniarz, M; Łyp, P; Adaszek, Ł; Wawron, W; Furmaga, B; Skrzypczak, M; Ziętek, J; Winiarczyk, S

    2016-09-01

    The aim of this study was to use matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of coagulase-negative staphylococci (CNS) isolated from the milk of cows with subclinical mastitis. The study material consisted of 33 isolates of CNS, identified by the results of API Staph tests, obtained from the milk of cows with subclinical mastitis. Based on the spectra analyses, MALDI-TOF MS tests of 33 bacterial samples allowed identification of the microorganisms in 27 cases (81.8%). The most frequent cause of subclinical mastitis was found to be Staphylococcus sciuri (39%), while S. vitulinus was detected in 15% of the milk samples. The results obtained indicate that MALDI-TOF MS can be used for the identification of CNS isolated from bovine mastitis as a method supplementary to biochemical tests.

  6. Structure and end-group analysis of complex hexanediol-neopentylglycol-adipic acid copolyesters by matrix-assisted laser desorption/ionization collision-induced dissociation tandem mass spectrometry.

    Science.gov (United States)

    Weidner, Steffen M; Falkenhagen, Jana; Knop, Karin; Thünemann, Andreas

    2009-09-01

    Sequences and end groups of complex copolyesters were determined by fragmentation analysis by means of matrix-assisted laser desorption/ionization collision-induced dissociation tandem mass spectrometry (MALDI CID MS/MS). The complexity of the crude copolyester mixture was reduced by a chromatographic separation followed by a MALDI time-of-flight (TOF) investigation of fractions. Due to overlapping compositional and end-group information a clear assignment of end groups was very difficult. However, the fragmentation of suitable precursor ions resulted in typical fragment ion patterns and, therefore, enabled a fast and unambiguous determination of the end groups and composition of this important class of polymers. Copyright (c) 2009 John Wiley & Sons, Ltd.

  7. Recognition of Streptococcus pseudoporcinus Colonization in Women as a Consequence of Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Group B Streptococcus Identification.

    Science.gov (United States)

    Suwantarat, Nuntra; Grundy, Maureen; Rubin, Mayer; Harris, Renee; Miller, Jo-Anne; Romagnoli, Mark; Hanlon, Ann; Tekle, Tsigereda; Ellis, Brandon C; Witter, Frank R; Carroll, Karen C

    2015-12-01

    During a 14-month period of using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for group B streptococcus (GBS) identification, we recovered 32 (1%) Streptococcus pseudoporcinus isolates from 3,276 GBS screening cultures from female genital sources (25 isolates from pregnant women and 7 from nonpregnant women). An additional two S. pseudoporcinus isolates were identified from a urine culture and a posthysterectomy wound culture. These isolates were found to cross-react with three different GBS antigen agglutination kits, PathoDx (Remel) (93%), Prolex (Pro-Lab Diagnostics) (38%), and Streptex (Remel) (53%). New approaches to bacterial identification in routine clinical microbiology laboratories may affect the prevalence of S. pseudoporcinus. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures – Application to the petroleomic analysis of bio-oils

    Energy Technology Data Exchange (ETDEWEB)

    Hertzog, Jasmine [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Carré, Vincent, E-mail: vincent.carre@univ-lorraine.fr [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Le Brech, Yann [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mackay, Colin Logan [SIRCAMS, School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, Scotland (United Kingdom); Dufour, Anthony [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mašek, Ondřej [UK Biochar Research Center, School of Geosciences, University of Edinburgh, Kings Buildings, Edinburgh, EH9 3JN (United Kingdom); and others

    2017-05-29

    The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to C{sub x}H{sub y}O{sub z} with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture. - Highlights: • Non-targeted mass spectrometry by combining electrospray ionization, atmospheric pressure photoionization and laser/desorption ionization. • Exhaustive description of pyrolytic bio-oil components. • Distinction of sugaric derivatives, lignin derivatives and lipids contained in a woody-based pyrolytic bio-oil.

  9. Surface-assisted laser desorption/ionization time-of-flight mass spectrometry of small drug molecules and high molecular weight synthetic/biological polymers using electrospun composite nanofibers.

    Science.gov (United States)

    Bian, Juan; Olesik, Susan V

    2017-03-27

    Polyacrylonitrile/Nafion®/carbon nanotube (PAN/Nafion®/CNT) composite nanofibers were prepared using electrospinning. These electrospun nanofibers were studied as possible substrates for surface-assisted laser desorption/ionization (SALDI) and matrix-enhanced surface-assisted laser desorption/ionization time-of-flight mass spectrometry (ME-SALDI/TOF-MS) for the first time in this paper. Electrospinning provides this novel substrate with a uniform morphology and a narrow size distribution, where CNTs were evenly and firmly immobilized on polymeric nanofibers. The results show that PAN/Nafion®/CNT nanofibrous mats are good substrates for the analysis of both small drug molecules and high molecular weight polymers with high sensitivity. Markedly improved reproducibility was observed relative to MALDI. Due to the composite formation between the polymers and the CNTs, no contamination of the carbon nanotubes to the mass spectrometer was observed. Furthermore, electrospun nanofibers used as SALDI substrates greatly extended the duration of ion signals of target analytes compared to the MALDI matrix. The proposed SALDI approach was successfully used to quantify small drug molecules with no interference in the low mass range. The results show that verapamil could be detected with a surface concentration of 220 femtomoles, indicating the high detection sensitivity of this method. Analysis of peptides and proteins with the electrospun composite substrate using matrix assisted-SALDI was improved and a low limit of detection of approximately 6 femtomoles was obtained for IgG. Both SALDI and ME-SALDI analyses displayed high reproducibility with %RSD ≤ 9% for small drug molecules and %RSD ≤ 14% for synthetic polymers and proteins.

  10. Ultraviolet laser desorption/ionization mass spectrometry of single-core and multi-core polyaromatic hydrocarbons under variable conditions of collisional cooling: insights into the generation of molecular ions, fragments and oligomers.

    Science.gov (United States)

    Gámez, Francisco; Hortal, Ana R; Martínez-Haya, Bruno; Soltwisch, Jens; Dreisewerd, Klaus

    2014-11-01

    The ultraviolet laser desorption/ionization of polyaromatic hydrocarbons (PAHs) has been investigated under different background pressures of an inert gas (up to 1.2 mbar of N2) in the ion source of a hybrid, orthogonal-extracting time-of-flight mass spectrometer (oTOF-MS). The study includes an ensemble of six model PAHs with isolated single polyaromatic cores and four ones with multiple cross-linked aromatic and polyaromatic cores. In combination with a weak ion extraction field, the variation of the buffer gas pressure allowed to control the degree of collisional cooling of the desorbed PAHs and, thus, to modulate their decomposition into fragments. The dominant fragmentation channels observed are related to dehydrogenation of the PAHs, in most cases through the cleavage of even numbers of C-H bonds. Breakage of C-C bonds leading to the fragmentation of rings, side chains and core linkages is also observed, in particular, at low buffer gas pressures. The precise patterns of the combined fragmentation processes vary significantly between the PAHs. The highest abundances of molecular PAH ions and cleanest mass spectra were consistently obtained at the highest buffer gas pressure of 1.2 mbar. The effective quenching of the fragmentation pathways at this elevated pressure improves the sensitivity and data interpretation for analytical applications, although the fragmentation of side chains and of bonds between (poly)aromatic cores is not completely suppressed in all cases. Moreover, these results suggest that the detected fragments are generated through thermal equilibrium processes rather than as a result of rapid photolysis. This assumption is further corroborated by a laser desorption/ionization post-source decay analysis using an axial time-of-flight MS. In line with these findings, covalent oligomers of the PAHs, which are presumably formed by association of two or more dehydrogenated fragments, are detected with higher abundances at the lower buffer gas

  11. Surface-Enhanced Raman Spectroelectrochemistry of TTF-Modified Self-Assembled Monolayers.

    Science.gov (United States)

    Paxton, Walter F; Kleinman, Samuel L; Basuray, Ashish N; Stoddart, J Fraser; Van Duyne, Richard P

    2011-05-19

    Surface-enhanced Raman spectroscopy (SERS) was used to monitor the response of a self-assembled monolayer (SAM) of a tetrathiafulvalene (TTF) derivative on a gold film-over-nanosphere electrode. The electrochemical response observed was rationalized in terms of the interactions between TTF moieties as the oxidation state was changed. Electrochemical oxidation to form the monocation caused the absorbance of the TTF unit to coincide with both the laser excitation wavelength and the localized surface plasmon resonance (LSPR), resulting in surface-enhanced resonance Raman scattering (SERRS). The vibrational frequency changes that accompany electron transfer afford a high-contrast mechanism that can be used to determine the oxidation state of the TTF unit in an unambiguous manner.

  12. Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators

    Science.gov (United States)

    Anderson, Mark S.

    2013-01-01

    The motivation of this work was to have robust spectroscopic sensors for sensitive detection and chemical analysis of organic and molecular compounds. The solution is to use silica sphere optical resonators to provide surface-enhanced spectroscopic signal. Whispering-gallery mode (WGM) resonators made from silica microspheres were used for surface-enhanced Raman scattering (SERS) without coupling to a plasmonic mechanism. Large Raman signal enhancement is observed by exclusively using 5.08-micron silica spheres with 785-nm laser excitation. The advantage of this non-plasmonic approach is that the active substrate is chemically inert silica, thermally stable, and relatively simple to fabricate. The Raman signal enhancement is broadly applicable to a wide range of molecular functional groups including aliphatic hydrocarbons, siloxanes, and esters. Applications include trace organic analysis, particularly for in situ planetary instruments that require robust sensors with consistent response.

  13. MoS{sub 2}/Ag nanohybrid: A novel matrix with synergistic effect for small molecule drugs analysis by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yaju, E-mail: daisy19900911@hotmail.com [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Deng, Guoqing, E-mail: denggqq@sina.com [Department of Polymer Science and Engineering, Nanjing University, Nanjing, 210023 (China); Liu, Xiaohui, E-mail: lcswyh@126.com [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Sun, Liang, E-mail: sunliang@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Li, Hui, E-mail: lihui@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Cheng, Quan, E-mail: quan.cheng@ucr.edu [Department of Chemistry, University of California, Riverside, CA, 92521 (United States); Xi, Kai, E-mail: xikai@nju.edu.cn [Department of Polymer Science and Engineering, Nanjing University, Nanjing, 210023 (China); Xu, Danke, E-mail: xudanke@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China)

    2016-09-21

    This paper reports a facile synthesis of molybdenum disulfide nanosheets/silver nanoparticles (MoS{sub 2}/Ag) hybrid and its use as an effective matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The nanohybrid exerts a strong synergistic effect, leading to high performance detection of small molecule analytes including amino acids, peptides, fatty acids and drugs. The enhancement of laser desorption/ionization (LDI) efficiency is largely attributed to the high surface roughness and large surface area for analyte adsorption, better dispersibility, increased thermal conductivity and enhanced UV energy absorption as compared to pure MoS{sub 2}. Moreover, both Ag nanoparticles and the edge of the MoS{sub 2} layers function as deprotonation sites for proton capture, facilitating the charging process in negative ion mode and promoting formation of negative ions. As a result, the MoS{sub 2}/Ag nanohybrid proves to be a highly attractive matrix in MALDI-TOF MS, with desired features such as high desorption/ionization efficiency, low fragmentation interference, high salt tolerance, and no sweet-spots for mass signal. These characteristic properties allowed for simultaneous analysis of eight different drugs and quantification of acetylsalicylic acid in the spiked human serum. This work demonstrates for the first time the fabrication and application of a novel MoS{sub 2}/Ag hybrid, and provides a new platform for use in the rapid and high throughput analysis of small molecules by mass spectrometry. - Highlights: • MoS{sub 2}/Ag nanohybrid was applied as a novel matrix in negative-ion MALDI-TOF MS. • The MoS{sub 2}/Ag nanohybrid exerted synergistic effect on the detection of small molecules. • The MoS{sub 2}/Ag nanohybrid showed good signal reproducibility and low background interferences comparing to organic matrices. • MoS{sub 2}/Ag allows simultaneous analysis of multiple drugs and quantification of

  14. Plasmonic dimer antennas for surface enhanced Raman scattering.

    Science.gov (United States)

    Höflich, Katja; Becker, Michael; Leuchs, Gerd; Christiansen, Silke

    2012-05-11

    Electron beam induced deposition (EBID) has recently been developed into a method to directly write optically active three-dimensional nanostructures. For this purpose a metal-organic precursor gas (here dimethyl-gold(III)-acetylacetonate) is introduced into the vacuum chamber of a scanning electron microscope where it is cracked by the focused electron beam. Upon cracking the aforementioned precursor gas, 3D deposits are realized, consisting of gold nanocrystals embedded in a carbonaceous matrix. The carbon content in the deposits hinders direct plasmonic applications. However, it is possible to activate the deposited nanostructures for plasmonics by coating the EBID structures with a continuous silver layer of a few nanometers thickness. Within this silver layer collective motions of the free electron gas can be excited. In this way, EBID structures with their intriguing precision at the nanoscale have been arranged in arrays of free-standing dimer antenna structures with nanometer sized gaps between the antennas that face each other with an angle of 90°. These dimer antenna ensembles can constitute a reproducibly manufacturable substrate for exploiting the surface enhanced Raman effect (SERS). The achieved SERS enhancement factors are of the order of 10⁴ for the incident laser light polarized along the dimer axes. To prove the signal enhancement in a Raman experiment we used the dye methyl violet as a robust test molecule. In future applications the thickness of such a silver layer on the dimer antennas can easily be varied for tuning the plasmonic resonances of the SERS substrate to match the resonance structure of the analytes to be detected.

  15. Raman and Surface Enhanced Raman of Biological Material

    National Research Council Canada - National Science Library

    Guicheteau, Jason A; Gonser, Kristina; Christesen, Steven Dale

    2004-01-01

    .... Vibrational spectroscopic methods such as Raman and surface enhanced Raman scattering (SERS) provide rapid detailed fingerprint information about the molecular composition of biomaterial in a non-destructive manner...

  16. Preparation of surface enhanced Raman substrate and its characterization

    Science.gov (United States)

    Liu, Y.; Wang, J. Y.; Wang, J. Q.

    2017-10-01

    Surface enhanced Raman spectroscopy (SERS) is a fast, convenient and highly sensitive detection technique, and preparing the good effect and repeatable substrate is the key to realize the trace amount and quantitative detection in the field of food safety detection. In this paper, a surface enhanced Raman substrate based on submicrometer silver particles structure was prepared by chemical deposition method, and characterized its structure and optical properties.

  17. Fiber-optic surface-enhanced Raman system for field screening of hazardous compounds

    International Nuclear Information System (INIS)

    Ferrell, T.L.; Goudonnet, J.P.; Arakawa, E.T.; Reddick, R.C.; Gammage, R.B.; Haas, J.W.; James, D.R.; Wachter, E.A.

    1988-01-01

    Surface-enhanced Raman scattering permits identification of compounds adsorbed onto a metal microbase that is microlithographically produced with submicron resolution. Less than one percent of a monolayer of a Raman Active target compound offers a high signal-to-noise ratio. By depositing the microbase on the exterior of a fiber optic cable, convenient field screening or monitoring is permitted. By using highly effective microbases, it is possible to reduce laser power requirements sufficiently to allow an economical, but complete, system to be housed in a suitcase. We shall present details of SERS system of this type and shall show data on samples of interest in the screening of hazardous compounds

  18. Characterization of O-glycosylated precursors of insulin-like growth factor II by matrix-assisted laser desorption/ionization mass spectrometry

    NARCIS (Netherlands)

    Jespersen, S.; Koedam, J.A.; Hoogerbrugge, C.M.; Tjaden, U.R.; Greef, J. van der; Brande, J.L. van den

    1996-01-01

    High molecular weight precursors of insulin-like growth factor II (IGF-II) were isolated from Cohn fraction IV of human plasma by ultrafiltration, affinity chromatography and reversed-phase high-performance liquid chromatography. Molecular weight determination by matrix-assisted laser

  19. Determination of saccharides in fruit juices by capillary electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Žídková, Jitka; Chmelík, Josef

    2001-01-01

    Roč. 36, č. 4 (2001), s. 417-421 ISSN 1076-5174 R&D Projects: GA MZe EP9410 Institutional research plan: CEZ:AV0Z4031919 Keywords : fruit juices * adulteration * matrix-assisted laser deasorption Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.685, year: 2001

  20. Surface-Enhanced Raman Scattering Physics and Applications

    CERN Document Server

    Kneipp, Katrin; Kneipp, Harald

    2006-01-01

    Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. Yet, explaining the enhancement of a spectroscopic signal by fouteen orders of magnitude continues to attract the attention of physicists and chemists alike. And, at the same time and rapidly growing, SERS is becoming a very useful spectroscopic tool with exciting applications in many fields. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This bookl summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.

  1. Resonance surface enhanced Raman optical activity of myoglobin as a result of optimized resonance surface enhanced Raman scattering conditions

    DEFF Research Database (Denmark)

    Abdali, Salim; Johannessen, Christian; Nygaard, Jesper

    2007-01-01

    Using Surface enhanced ROA (SEROA), novel results are achieved by combining Raman Optical Activity (ROA) and resonance Surface Enhanced Raman Scattering (SERRS), applied on myoglobin. The novelty of this work is ascribed the first time reporting on chiral results of a study performed on a protein...... has shown that the SERS effect behaves consequently, depending on the concentration ratio of each component, i.e., myoglobin, Ag colloids and NaCl. Accordingly, it is shown here that SERS intensity has its maximum at certain concentration of these components, whereas below or above this value...

  2. Metal-coated magnetic nanoparticles for surface enhanced Raman ...

    Indian Academy of Sciences (India)

    magnetic properties of these nanoparticles combined with SERS provide a wide range of applications. Keywords. Surface-enhanced Raman scattering; magnetic nanoparticles; core-shell nanostructure; bio-diagnosis. 1. Introduction. In recent years, plasmonic nanostructures exhibiting novel optical properties have attracted ...

  3. Metal-coated magnetic nanoparticles for surface enhanced Raman ...

    Indian Academy of Sciences (India)

    We report the optimization and usage of surfactantless, water dispersible Ag and Au-coated γ–Fe2O3 nanoparticles for applications in surface-enhanced .... After the solvent evaporated, 2 μL of analyte of ∼1 μM concentration was ..... dry soil, and comprised of smooth, distinct, rectangular and square shaped islands, whose ...

  4. Surface enhanced Raman spectra of the organic nonlinear optic ...

    Indian Academy of Sciences (India)

    Wintec

    Institute of Chemistry, University of Opole, Olesksa 48 45-052 Opole, Poland. 1. Present Address: Department of Physics, V.P.S.H.S.S. for ... co-ordination chemistry. Surface-enhanced Raman scattering (SERS), using .... numbers were calculated using analytic second de- rivatives to confirm the convergence to minima on.

  5. Near-Ir surface-enhanced Raman spectrum of lignin

    Science.gov (United States)

    Umesh P. Agarwal; Richard S. Reiner

    2009-01-01

    Compacted powders of commercially available nano- and microparticles of silver were used to successfully induce the surface enhanced Raman scattering (SERS) effect in spruce milled-wood lignin (MWL). For the two silver particle sizes used in this investigation, the spectra were mostly similar. Some general characteristics of the lignin SERS spectrum are described. The...

  6. Asphaltene detection using surface enhanced Raman scattering (SERS).

    Science.gov (United States)

    Alabi, O O; Edilbi, A N F; Brolly, C; Muirhead, D; Parnell, J; Stacey, R; Bowden, S A

    2015-04-28

    Surface enhanced Raman spectroscopy using a gold substrate and excitation at 514 nm can detect sub parts per million quantities of asphaltene and thereby petroleum. This simple format and sensitivity make it transformative for applications including sample triage, flow assurance, environmental protection and analysis of unique one of a kind materials.

  7. Surface-enhanced Raman spectroscopy of DNA bases

    NARCIS (Netherlands)

    Otto, Cornelis; van den Tweel, T.J.J.; de Mul, F.F.M.; Greve, Jan

    1986-01-01

    A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS

  8. Surface enhanced Raman spectroscopy platform based on graphene with one-year stability

    Energy Technology Data Exchange (ETDEWEB)

    Tite, Teddy [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France); Barnier, Vincent [Ecole Nationale Supérieure des Mines, CNRS, Laboratoire Georges Friedel UMR 5307, 158 cours Fauriel, F-42023 Saint-Etienne (France); Donnet, Christophe, E-mail: Christophe.Donnet@univ-st-etienne.fr [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France); Loir, Anne–Sophie; Reynaud, Stéphanie; Michalon, Jean–Yves; Vocanson, Francis; Garrelie, Florence [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France)

    2016-04-01

    We report the synthesis, characterization and use of a robust surface enhanced Raman spectroscopy platform with a stable detection for up to one year of Rhodamine R6G at a concentration of 10{sup −6} M. The detection of aminothiophenol and methyl parathion, as active molecules of commercial insecticides, is further demonstrated at concentrations down to 10{sup −5}–10{sup −6} M. This platform is based on large scale textured few-layer (fl) graphene obtained without any need of graphene transfer. The synthesis route is based on diamond-like carbon films grown by pulsed laser deposition, deposited onto silicon substrates covered by a Ni layer prior to diamond-like carbon deposition. The formation of fl-graphene film, confirmed by Raman spectroscopy and mapping, is obtained by thermal annealing inducing the diffusion of Ni atoms and the concomitant formation of nickel silicide compounds, as identified by Raman and Auger electron spectroscopies. The textured fl-graphene films were decorated with gold nanoparticles to optimize the efficiency of the SERS device to detect organic molecules at low concentrations. - Highlights: • Synthesis of graphene film from amorphous carbon by pulsed laser deposition with nickel catalyst • Large scale textured graphene with nanoscale roughness obtained through nickel silicide formation • Films used for surface enhanced Raman spectroscopy detection of organophosphate compounds • Stability of the SERS platforms over up to one year.

  9. Microorganisms in cryopreserved semen and culture media used in the in vitro production (IVP) of bovine embryos identified by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS).

    Science.gov (United States)

    Zampieri, Dávila; Santos, Vanessa G; Braga, Patrícia A C; Ferreira, Christina R; Ballottin, Daniela; Tasic, Ljubica; Basso, Andréa C; Sanches, Bruno V; Pontes, José H F; da Silva, Bárbara Pereira; Garboggini, Fabiana Fantinatti; Eberlin, Marcos N; Tata, Alessandra

    2013-09-01

    Commercial cattle breeders produce their own herd offspring for the dairy and beef market using artificial insemination. The procedure involves sanitary risks associated with the collection and commercialization of the germplasm, and the in vitro production and transfer of the bovine embryos must be monitored by strict health surveillance. To avoid the spreading of infectious diseases, one must rely on using controlled and monitored germplasm, media, and reagents that are guaranteed free of pathogens. In this article, we investigated the use of a new mass spectrometric approach for fast and accurate identification of bacteria and fungi in bovine semen and in culture media employed in the embryo in vitro production process. The microorganisms isolated from samples obtained in a commercial bovine embryo IVP setting were identified in a few minutes by their conserved peptide/protein profile, obtained applying matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), matched against a commercial database. The successful microorganisms MS identification has been confirmed by DNA amplification and sequencing. Therefore, the MS technique seems to offer a powerful tool for rapid and accurate microorganism identification in semen and culture media samples. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Sensitive analyses of neutral N-glycans using anion-doped liquid matrix G3CA by negative-ion matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Nishikaze, Takashi; Fukuyama, Yuko; Kawabata, Shin-ichirou; Tanaka, Koichi

    2012-07-17

    Negative-ion fragmentation of N-glycans has been proven to be more informative than that of positive-ion. In particular, it defines structural features such as the specific composition of the two antennae and the location of fucose. However, negative-ion formation of neutral N-glycans by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) remains a challenging task, and the detection limit of N-glycans in negative-ion mode is merely at the subpicomole level. Thus, practical applications are limited. In this study, combinations of five liquid matrices and nine anions were used to ionize N-glycans as anionic adducts, and their performances for sensitive analyses were evaluated. The best results were obtained with anion-doped liquid matrix G(3)CA, which consists of p-coumaric acid and 1,1,3,3-tetramethylguanidine; the detection limits of anion adducted N-glycans were 1 fmol/well for NO(3)(-), and 100 amol/well for BF(4)(-). Negative-ion MS(2) spectra of 1 fmol N-glycans were successfully acquired with a sufficient signal-to-noise ratio and were quite useful for MS-based structural determination. The anion-doped G(3)CA matrix opens the way for sensitive and rapid analysis of neutral N-glycans in negative-ion MALDI at a low femtomole level.

  11. Facile Synthesis of N-Doped Carbon Dots as a New Matrix for Detection of Hydroxy-Polycyclic Aromatic Hydrocarbons by Negative-Ion Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Lu, Wenjing; Li, Yong; Li, Ruijin; Shuang, Shaomin; Dong, Chuan; Cai, Zongwei

    2016-05-25

    N-doping carbon dots (N-CDs) were prepared by microwave-assisted pyrolysis of dl-malic acid and ethanolamine as precursors. The material served as an excellent matrix for the detection of the environmental pollutants hydroxy-polycyclic aromatic hydrocarbons (OH-PAHs) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in negative ion mode. The obtained N-CDs exhibited good UV absorption capacity and favorable solubility. The use of the N-CDs matrix exhibited low matrix background interference and was beneficial to improve the signal response due to the specific π-conjugated polyaromatic structure and the doping of nitrogen atoms. The developed method was found to have good reproducibility and sensitivity. The N-CDs as a new matrix also were employed for the detection of OH-PAHs in real PM2.5 samples. The mass concentrations of Σ-hydroxy-pyrene, Σ-dihydroxy-anthraquinone, and Σ-dihydroxy-benzo(a)pyrene on the collected PM2.5 samples ranged from 0.125 to 0.136 ng/m(3), 0.039 to 0.052 ng/m(3), and 0.053 to 0.072 ng/m(3), respectively. This work extends the application field of N-CDs and provides a good candidate of matrix for MALDI-TOF MS detection of environmental pollutants.

  12. Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    Science.gov (United States)

    Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

    2017-12-01

    N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. [Figure not available: see fulltext.

  13. Identification of the degradome of Isp-1, a major intracellular serine protease of Bacillus subtilis, by two-dimensional gel electrophoresis and matrix- assisted laser desorption/ionization-time of flight analysis.

    Science.gov (United States)

    Lee, Ah Young; Goo Park, Sung; Kho, Chang Won; Young Park, Sun; Cho, Sayeon; Lee, Sang Chul; Lee, Do Hee; Myung, Pyung Keun; Park, Byoung Chul

    2004-11-01

    Intracellular serine protease-1 (Isp-1) is a major intracellular serine protease of Bacillus subtilis, whose functions still remain largely unknown. Furthermore, physiological substrates are yet to be determined. To identify Isp-1 substrates, we digested extract obtained from an Isp-1 deficient Bacillus mutant with purified Isp-1 and examined eliminated or decreased spots by two-dimensional gel and matrix-assisted laser desorption/ionization-time of flight analyses. Proteins degraded by Isp-1, termed the Isp-1 degradome, are involved in a variety of cellular functions such as DNA packing, genetic competence, and protein secretion. From the degradome we selected ClpC and EF-Tu as putative Isp-1 substrates and studied their in vitro degradation. ClpC and EF-Tu contain putative cleavage sites for Isp-1. N-terminal sequencing of in vitro proteolytic fragments of ClpC and EF-Tu revealed that these sites are indeed recognized and cleaved by Isp-1. Moreover, the cellular levels of ClpC and EF-Tu were dramatically reduced at the late stationary phase, where the expression level of Isp-1 was greatly increased. These results suggest that the regulated proteolysis of ClpC by Isp-1 plays an important role in the stationary phase adaptive response. This degradomic approach could provide a powerful tool for finding physiological substrates of many proteolytic enzymes whose functions remain to be determined.

  14. Optimization and Evaluation of Magnetic Bead Separation Combined with Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectroscopy (MALDI-TOF MS for Proteins Profiling of Peritoneal Dialysis Effluent

    Directory of Open Access Journals (Sweden)

    Na Guo

    2014-01-01

    Full Text Available Peritoneal dialysis effluent (PDE potentially carries an archive of peptides relevant to pathological processes in abdominal and surrounding tissues. Magnetic beads and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is one such approach that offers a unique tool for profiling of peptides, but this approach has not been used in the PDE analysis. In this study, we developed a strategy for screening PDE proteins <15 kDa and applied this technique to identify potential biomarkers for peritonitis. We examined four kinds of magnetic beads, including a carbon series (C3, C8, weak cation exchange (WCX and immobilized metal-affinity chromatography (IMAC-Cu beads. Samples processed with IMAC-Cu magnetic beads consistently showed more MS signals across all beads within the measured mass range. Moreover, there was no difference in the number and morphology of MS signals between concentrated and unconcentrated samples. The PDE peptidome pattern, based on a panel of 15 peaks, accurately recognized peritonitis PD patients from peritonitis-free patients with sensitivity of 90.5% and specificity of 94.7% respectively. Therefore, IMAC-Cu magnetic beads and unconcentrated samples can be used as a fast and cost-effective approach for sample preparation prior to more in-depth discovery of predictive biomarkers of disease in patients on dialysis.

  15. Utilization of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry for identification of infantile seborrheic dermatitis-causing Malassezia and incidence of culture-based cutaneous Malassezia microbiota of 1-month-old infants.

    Science.gov (United States)

    Yamamoto, Mikachi; Umeda, Yoshiko; Yo, Ayaka; Yamaura, Mariko; Makimura, Koichi

    2014-02-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been utilized for identification of various microorganisms. Malassezia species, including Malassezia restricta, which is associated with seborrheic dermatitis, has been difficult to identify by traditional means. This study was performed to develop a system for identification of Malassezia species with MALDI-TOF-MS and to investigate the incidence and variety of cutaneous Malassezia microbiota of 1-month-old infants using this technique. A Malassezia species-specific MALDI-TOF-MS database was developed from eight standard strains, and the availability of this system was assessed using 54 clinical strains isolated from the skin of 1-month-old infants. Clinical isolates were cultured initially on CHROMagar Malassezia growth medium, and the 28S ribosomal DNA (D1/D2) sequence was analyzed for confirmatory identification. Using this database, we detected and analyzed Malassezia species in 68% and 44% of infants with and without infantile seborrheic dermatitis, respectively. The results of MALDI-TOF-MS analysis were consistent with those of rDNA sequencing identification (100% accuracy rate). To our knowledge, this is the first report of a MALDI-TOF-MS database for major skin pathogenic Malassezia species. This system is an easy, rapid and reliable method for identification of Malassezia. © 2014 Japanese Dermatological Association.

  16. Heterotrophic monitoring at a drinking water treatment plant by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry after different drinking water treatments.

    Science.gov (United States)

    Sala-Comorera, Laura; Blanch, Anicet R; Vilaró, Carles; Galofré, Belén; García-Aljaro, Cristina

    2017-10-01

    The aim of this work was to assess the suitability of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for routine heterotrophic monitoring in a drinking water treatment plant. Water samples were collected from raw surface water and after different treatments during two campaigns over a 1-year period. Heterotrophic bacteria were studied and isolates were identified by MALDI-TOF MS. Moreover, the diversity index and the coefficient of population similarity were also calculated using biochemical fingerprinting of the populations studied. MALDI-TOF MS enabled us to characterize and detect changes in the bacterial community composition throughout the water treatment plant. Raw water showed a large and diverse population which was slightly modified after initial treatment steps (sand filtration and ultrafiltration). Reverse osmosis had a significant impact on the microbial diversity, while the final chlorination step produced a shift in the composition of the bacterial community. Although MALDI-TOF MS could not identify all the isolates since the available MALDI-TOF MS database does not cover all the bacterial diversity in water, this technique could be used to monitor bacterial changes in drinking water treatment plants by creating a specific protein profile database for tracking purposes.

  17. Metabolomic insights into the effects of thyroid hormone on Rana [Lithobates] catesbeiana metamorphosis using whole-body Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging (MALDI-MSI).

    Science.gov (United States)

    Luehr, Teesha C; Koide, Emily M; Wang, Xiaodong; Han, Jun; Borchers, Christoph H; Helbing, Caren C

    2018-02-19

    Anuran metamorphosis involves the transformation of an aquatic tadpole into a juvenile frog. This process is completely dependent upon thyroid hormones (THs). Although much research has been focused on changes in gene expression programs during this postembryonic developmental period, transitions in the metabolic profiles are relatively poorly understood. Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging (MALDI-MSI) is a technique that generates highly multiplexed mass spectra while retaining spatial location information on a thin tissue section. Reconstructed ion heat maps are correlated with morphology of the tissue section for biological interpretation. The present study is the first to use whole-body MALDI-MSI on tadpoles to gain insights into anuran metamorphosis. Approximately 1000 features were detected in each of five tissues examined (brain, eye, liver, notochord, and tail muscle) from premetamorphic North American bullfrog (Rana [Lithobates] catesbeiana) tadpoles. Of these detected metabolites, 1700 were unique and 136 were significantly affected by exposure to 50 nM thyroxine for 48 h. Of the significantly-affected metabolites, 64 features were tentatively identified using the MassTRIX annotation tool. All tissues revealed changes in lipophilic compounds including phosphatidylcholines, phosphatidylinositols, phosphatidylglycerols, phosphatidylethanolamines, and phosphatidylserines. These lipophilic compounds made up the largest portion of significantly-affected metabolites indicating that lipid signaling is a major target of TH action in frog tadpoles. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Evaluation of repetitive-PCR and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for rapid strain typing of Bacillus coagulans.

    Science.gov (United States)

    Sato, Jun; Nakayama, Motokazu; Tomita, Ayumi; Sonoda, Takumi; Hasumi, Motomitsu; Miyamoto, Takahisa

    2017-01-01

    In order to establish rapid and accurate typing method for Bacillus coagulans strains which is important for controlling in some canned foods and tea-based beverages manufacturing because of the high-heat resistance of the spores and high tolerance of the vegetative cells to catechins and chemicals, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and repetitive-PCR (rep-PCR) were evaluated. For this purpose, 28 strains of B. coagulans obtained from various culture collections were tested. DNA sequence analyses of the genes encoding 16S rRNA and DNA gyrase classified the test strains into two and three groups, respectively, regardless of their phenotypes. Both MALDI-TOF MS and rep-PCR methods classified the test strains in great detail. Strains classified in each group showed similar phenotypes, such as carbohydrate utilization determined using API 50CH. In particular, the respective two pairs of strains which showed the same metabolic characteristic were classified into the same group by both MALDI-TOF MS and rep-PCR methods separating from the other strains. On the other hand, the other strains which have the different profiles of carbohydrate utilization were separated into different groups by these methods. These results suggested that the combination of MALDI-TOF MS and rep-PCR analyses was advantageous for the rapid and detailed typing of bacterial strains in respect to both phenotype and genotype.

  19. Evaluation of repetitive-PCR and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS for rapid strain typing of Bacillus coagulans.

    Directory of Open Access Journals (Sweden)

    Jun Sato

    Full Text Available In order to establish rapid and accurate typing method for Bacillus coagulans strains which is important for controlling in some canned foods and tea-based beverages manufacturing because of the high-heat resistance of the spores and high tolerance of the vegetative cells to catechins and chemicals, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS and repetitive-PCR (rep-PCR were evaluated. For this purpose, 28 strains of B. coagulans obtained from various culture collections were tested. DNA sequence analyses of the genes encoding 16S rRNA and DNA gyrase classified the test strains into two and three groups, respectively, regardless of their phenotypes. Both MALDI-TOF MS and rep-PCR methods classified the test strains in great detail. Strains classified in each group showed similar phenotypes, such as carbohydrate utilization determined using API 50CH. In particular, the respective two pairs of strains which showed the same metabolic characteristic were classified into the same group by both MALDI-TOF MS and rep-PCR methods separating from the other strains. On the other hand, the other strains which have the different profiles of carbohydrate utilization were separated into different groups by these methods. These results suggested that the combination of MALDI-TOF MS and rep-PCR analyses was advantageous for the rapid and detailed typing of bacterial strains in respect to both phenotype and genotype.

  20. Comparative evaluation of matrix-assisted laser desorption ionisation-time of flight mass spectrometry and conventional phenotypic-based methods for identification of clinically important yeasts in a UK-based medical microbiology laboratory.

    Science.gov (United States)

    Fatania, Nita; Fraser, Mark; Savage, Mike; Hart, Jason; Abdolrasouli, Alireza

    2015-12-01

    Performance of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) was compared in a side-by side-analysis with conventional phenotypic methods currently in use in our laboratory for identification of yeasts in a routine diagnostic setting. A diverse collection of 200 clinically important yeasts (19 species, five genera) were identified by both methods using standard protocols. Discordant or unreliable identifications were resolved by sequencing of the internal transcribed spacer region of the rRNA gene. MALDI-TOF and conventional methods were in agreement for 182 isolates (91%) with correct identification to species level. Eighteen discordant results (9%) were due to rarely encountered species, hence the difficulty in their identification using traditional phenotypic methods. MALDI-TOF MS enabled rapid, reliable and accurate identification of clinically important yeasts in a routine diagnostic microbiology laboratory. Isolates with rare, unusual or low probability identifications should be confirmed using robust molecular methods. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  1. High-sensitivity matrix-assisted laser desorption/ionization Fourier transform mass spectrometry analyses of small carbohydrates and amino acids using oxidized carbon nanotubes prepared by chemical vapor deposition as matrix.

    Science.gov (United States)

    Wang, Cui-hong; Li, Jian; Yao, Sheng-jun; Guo, Yin-long; Xia, Xing-hua

    2007-12-05

    In matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) analyses of small oligosaccharides and amino acids, high sensitivities for oligosaccharides (10 fmol) were obtained by introducing oxidized carbon nanotubes (CNTs) with short and open-end structure as valuable matrix. The CNTs were deposited in porous anodic alumina (PAA) templates by chemical vapor deposition. Transmission electron microscopy (TEM) images show that those CNTs include low levels of amorphous carbon. Thus, the background interference signals generally caused by amorphous carbon powder in CNTs can be reduced effectively. Experiments also confirmed that the FTMS signal intensity of CNTs prepared in PAA template is much lower than that of commercial multi-wall carbon nanotubes (MCNTs). Moreover, the purified process for CNTs with mixed acid (H2SO4 and HNO3) also contributed to the minimization of background. Intense signals corresponding to alkali cation adduct of neutral carbohydrates and amino acids have been acquired. In addition, reliable quantitative analyses for urine and corn root were also achieved successfully. The present work will open a new way to the application of oxidized CNTs as an effective matrix in MALDI MS research.

  2. Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing.

    Science.gov (United States)

    Gitman, Melissa R; McTaggart, Lisa; Spinato, Joanna; Poopalarajah, Rahgavi; Lister, Erin; Husain, Shahid; Kus, Julianne V

    2017-07-01

    Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods. © Crown copyright 2017.

  3. Global proteomic analysis of plasma from mice infected with Plasmodium berghei ANKA using two dimensional gel electrophoresis and matrix assisted laser desorption ionization-time of flight mass spectrometry

    Directory of Open Access Journals (Sweden)

    Kokwaro Gilbert O

    2011-07-01

    Full Text Available Abstract Background A global proteomic strategy was used to identify proteins, which are differentially expressed in the murine model of severe malaria in the hope of facilitating future development of novel diagnostic, disease monitoring and treatment strategies. Methods Mice (4-week-old CD1 male mice were infected with Plasmodium berghei ANKA strain, and infection allowed to establish until a parasitaemia of 30% was attained. Total plasma and albumin depleted plasma samples from infected and control (non-infected mice were separated by two-dimensional gel electrophoresis (2-DE. After staining, the gels were imaged and differential protein expression patterns were interrogated using image analysis software. Spots of interest were then digested using trypsin and the proteins identified using matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF mass spectrometry (MS and peptide mass fingerprinting software. Results Master gels of control and infected mice, and the corresponding albumin depleted fractions exhibited distinctly different 2D patterns comparing control and infected plasma, respectively. A wide range of proteins demonstrated altered expression including; acute inflammatory proteins, transporters, binding proteins, protease inhibitors, enzymes, cytokines, hormones, and channel/receptor-derived proteins. Conclusions Malaria-infection in mice results in a wide perturbation of the host serum proteome involving a range of proteins and functions. Of particular interest is the increased secretion of anti-inflammatory and anti apoptotic proteins.

  4. Evaluation of species-specific score cutoff values of routinely isolated clinically relevant bacteria using a direct smear preparation for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based bacterial identification.

    Science.gov (United States)

    Szabados, F; Tix, H; Anders, A; Kaase, M; Gatermann, S G; Geis, G

    2012-06-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was introduced a few years ago as a new method for bacterial identification. A variety of studies have been published concerning MALDI-TOF MS-based identification, most of them using culture collections for the validation of the respective databases in a retrospective manner in favor of a parallel investigation. The score cutoff value is of special importance for reliable species identification in the Biotyper database. The score cutoff values suggested by the manufacturer have been validated using a previously published formic acid extraction protocol. In most of the previously published studies investigating the Biotyper database, only little information was given concerning species-specific score values. In addition, the mass spectrometer instruments, the number of replicates, the number of spectra used to calculate a sum-spectrum by the supplied software, and the score cutoff values which have been applied varied within these studies. In this study, we compared a straightforward direct smear preparation and measurement without replicate testing to defined biochemical identifications in a parallel manner. In addition, we described new species-specific score cutoff values for the identification of certain bacteria.

  5. Characterization of Klebsiella isolates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and determination of antimicrobial resistance with VITEK 2 advanced expert system (AES).

    Science.gov (United States)

    Karagöz, Alper; Acar, Sümeyra; Körkoca, Hanifi

    2015-01-01

    The purpose of the study was to evaluate the performance of the VITEK mass spectrometry (MS) (bioMérieux, France) system for the identification of Klebsiella spp. isolated from different sources. Moreover, while assessing the ability of the VITEK 2 automated expert system (AES) to recognize antimicrobial resistance patterns, the researchers have extended the study to compare VITEK 2 with the routine antimicrobial susceptibility testing method. This study tested 51 Klebsiella spp. isolates that were isolated from environmental examples and clinical examples. Results of conventional methods and the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS were compared. Then, any differing results were compared against a reference 16S rRNA gene sequence, and when indicated, a recA sequencing analysis was done. VITEK MS correctly identified 100% of the Klebsiella spp. isolates. There were two K. oxytoca isolates incorrectly identified to the species level with conventional methods according to the 16S rRNA gene sequencing analysis. In addition, a VITEK 2 AST-N261 card was used for the detection of extended spectrum beta-lactamases (ESBL). Using the VITEK 2 AES, ESBL positivity was found at the rate of 16.3% whereas this rate was 4.08% using the disk diffusion method. MALDI-TOF MS is a rapid and accurate method for the identification of Klebsiella spp. Moreover, the bioMérieux AES provides a useful laboratory tool for the interpretation of susceptibility results.

  6. Method for simultaneous imaging of endogenous low molecular weight metabolites in mouse brain using TiO2 nanoparticles in nanoparticle-assisted laser desorption/ionization-imaging mass spectrometry.

    Science.gov (United States)

    Shrivas, Kamlesh; Hayasaka, Takahiro; Sugiura, Yuki; Setou, Mitsutoshi

    2011-10-01

    We report the detection of a group of endogenous low molecular weight metabolites (LMWM) in mouse brain (80-500 Da) using TiO(2) nanoparticles (NPs) in nanoparticle-assisted laser desorption/ionization-imaging mass spectrometry (Nano-PALDI-IMS) without any washing and separation step prior to MS analysis. The identification of metabolites using TiO(2) NPs was compared with a conventional organic matrix 2,5-dihydroxybenzoic acid (DHB) where signals of 179 molecules were specific to TiO(2) NPs, 4 were specific to DHB, and 21 were common to both TiO(2) NPs and DHB. The use of TiO(2) NPs enabled the detection of a higher number of LMWM as compared to DHB and gold NPs as a matrix. This approach is a simple, inexpensive, washing, and separation free for imaging and identification of LMWM in mouse brain. We believe that the biochemical information from distinct regions of the brain using a Nano-PALDI-IMS will be helpful in elucidating the imbalances linked with diseases in biomedical samples.

  7. Classification of protein binders in artist's paints by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry: an evaluation of principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA).

    Science.gov (United States)

    Fremout, Wim; Kuckova, Stepanka; Crhova, Michaela; Sanyova, Jana; Saverwyns, Steven; Hynek, Radovan; Kodicek, Milan; Vandenabeele, Peter; Moens, Luc

    2011-06-15

    Proteomics techniques are increasingly applied for the identification of protein binders in historical paints. The complex nature of paint samples, with different kinds of pigments mixed into, and degradation by long term exposure to light, humidity and temperature variations, requires solid analysis and interpretation methods. In this study matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectra of tryptic-digested paint replicas are subjected to principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) in order to distinguish proteinaceous binders based on animal glues, egg white, egg yolk and milk casein from each other. The most meaningful peptide peaks for a given protein class will be determined, and if possible, annotated with their corresponding amino acid sequence. The methodology was subsequently applied on egg temperas, as well as on animal glues from different species. In the latter small differences in the MALDI-TOF mass spectra can allow the determination of a mammal or sturgeon origin of the glue. Finally, paint samples from the 16(th) century altarpiece of St Margaret of Antioch (Mlynica, Slovakia) were analysed. Several expected peaks are either present in lower abundance or completely missing in these natural aged paints, due to degradation of the paints. In spite of this mammalian glue was identified in the St Margaret samples. Copyright © 2011 John Wiley & Sons, Ltd.

  8. Abattoirs as non-hospital source of extended spectrum beta lactamase producers: confirmed by the double disc synergy test and characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Moses Nkechukwu Ikegbunam

    Full Text Available In this study, the presence of extended spectrum beta lactamase (ESBL producing organisms in abattoirs, a non-hospital community was investigated. The presence of ESBL-producing phenotypes was confirmed by the Double Disc Synergy Test (DDST. Out of the 99 isolates screened for ESBL, 28 (28.3% were confirmed positive. The positive isolates were characterised by using Matrix-Assisted Laser Desorption/Ionization Time of flight Mass Spectrometry. 50% of the isolates were Pseudomonas spp., the rest were different species of Acinetobacter, Stenotrophomonas and Achromobacter. Pseudomonas monteilli and Pseudomonas putida were the most occurring in the intestine. The entire positive ESBL producers were subjected to plasmid curing to ascertain the location of the resistant marker. The result of the plasmid curing indicated that the resistant genes were chromosomally borne. The findings have therefore established the presence of ESBL producing organisms in the gut of animals from abattoirs and the table were the meat are sold, and its rate of occurrence is comparable to hospital ICUs. Abattoir communities could probably be a source of human infection with ESBL expressing pathogens and possible transfer to non-ESBL producers.

  9. Superbasic alkyl-substituted bisphosphazene proton sponges: a new class of deprotonating matrices for negative ion matrix-assisted ionization/laser desorption mass spectrometry of low molecular weight hardly ionizable analytes.

    Science.gov (United States)

    Calvano, C D; Cataldi, T R I; Kögel, J F; Monopoli, A; Palmisano, F; Sundermeyer, J

    2016-07-30

    Here hardly ionizable and low molecular weight compounds are detected in negative ion mode by using novel superbasic proton sponges based on 1,8-bisphosphazenylnaphthalene (PN) as MALDI matrices. Among the selected proton sponges, 1,8-bis(trispyrrolidinophosphazenyl)naphthalene (TPPN) has shown the best behaviour as matrix since it allows the direct detection of intact cholesterol without derivatization also in real challenging samples. Very weakly acidic compounds such as sterols, steroids, fatty alcohols and saccharides were detected in reflectron negative ion mode by a MALDI TOF/TOF system equipped with a neodymium-doped yttrium lithium fluoride (Nd:YLF) laser (345 nm) with typical mass accuracy of 10 ppm. MS/MS experiments were performed by using ambient air as the collision gas. Contrary to traditional MALDI matrices, superbasic proton sponges allowed the easy deprotonation of an alcohol functional group without a previous chemical derivatization step. Experimental evidence indicates that analyte deprotonation is achieved in the condensed phase, i.e. PN superbasic proton sponges operate according to a recently proposed model named matrix assisted ionization/laser desorption (MAILD). A detection limit of 3 pmol/spot of cholesterol (model compound) with a signal-to-noise ratio ≥ 10 was typically obtained. For the first time, the usefulness of novel superbasic proton sponges is demonstrated for MALDI detection of hardly ionizable compounds such as sterols, steroids, fatty alcohols and saccharides. The leading candidate TPPN has been successfully applied for negative ion MAILD-MS analysis of cholesterol, fatty acids and phospholipids in egg yolk and brain tissue extracts. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Utility of imaging mass spectrometry (IMS) by matrix-assisted laser desorption ionization (MALDI) on an ion trap mass spectrometer in the analysis of drugs and metabolites in biological tissues.

    Science.gov (United States)

    Drexler, Dieter M; Garrett, Timothy J; Cantone, Joseph L; Diters, Richard W; Mitroka, James G; Prieto Conaway, Maria C; Adams, Stephen P; Yost, Richard A; Sanders, Mark

    2007-01-01

    The properties and potential liabilities of drug candidate are investigated in detailed ADME assays and in toxicity studies, where findings are placed in context of exposure to dosed drug and metabolites. The complex nature of biological samples may necessitate work-up procedures prior to high performance liquid chromatography-mass spectrometric (HPLC-MS) analysis of endogenous or xenobiotic compounds. This concept can readily be applied to biological fluids such as blood or urine, but in localized samples such as organs and tissues potentially important spatial, thus anatomical, information is lost during sample preparation as the result of homogenization and extraction procedures. However, the localization of test article or spatial identification of metabolites may be critical to the understanding of the mechanism of target-organ toxicity and its relevance to clinical safety. Tissue imaging mass spectrometry (IMS) by matrix-assisted laser desorption ionization (MALDI) and ion trap mass spectrometry (MS) with higher order mass spectrometric scanning functions was utilized for localization of dosed drug or metabolite in tissue. Laser capture microscopy (LCM) was used to obtain related samples from tissue for analyses by standard MALDI-MS and HPLC-MS. In a toxicology study, rats were administered with a high dosage of a prodrug for 2 weeks. Birefringent microcrystalline material (10-25 microm) was observed in histopathologic formalin-fixed tissue samples. Direct analysis by IMS provided the identity of material in the microcrystals as circulating active drug while maintaining spatial orientation. Complementary data from visual cross-polarized light microscopy as well as standard MALDI-MS and HPLC-MS experiments on LCM samples validated the qualitative results obtained by IMS. Furthermore, the HPLC-MS analysis on the LCM samples afforded a semi-quantitative assessment of the crystalline material in the tissue samples. IMS by MALDI ion trap MS proved sensitive

  11. In situ analysis of plant tissue underivatized carbohydrates and on-probe enzymatic degraded starch by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry by using carbon nanotubes as matrix.

    Science.gov (United States)

    Gholipour, Yousef; Nonami, Hiroshi; Erra-Balsells, Rosa

    2008-12-15

    Underivatized carbohydrates of tulip bulb and leaf tissues were characterized in situ by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) by using carbon nanotubes (CNTs) as matrix. Two sample preparation methods--(i) depositing CNTs on the fresh tissue slices placed on the probe and (ii) locating semitransparent tissues on a dried layer of CNTs on the probe--were examined. Furthermore, practicability of in situ starch analysis by MALDI-TOF MS was examined by detection of glucose originated from on-probe amyloglucosidase-catalyzed degradation of starch on the tissue surface. Besides, CNTs could efficiently desorb/ionize natural mono-, di-, and oligosaccharides extracted from tulip bulb tissues as well as glucose resulting from starch enzymatic degradation in vitro. These results were compared with those obtained by in situ MALDI-TOF MS analysis of similar tissues. Positive ion mode showed superior signal reproducibility. CNTs deposited under semitransparent tissue could also desorb/ionize neutral carbohydrates, leading to nearly complete elimination of matrix cluster signals but with an increase in tissue-originated signals. Furthermore, several experiments were carried out to compare the efficiency of 2,5-dihydroxybenzoic acid, nor-harmane, alpha-cyano-4-hydroxycinnamic acid, and CNTs as matrices for MALDI of neutral carbohydrates from the intact plant tissue surface and for enzymatic tissue starch degradation; these results are discussed in brief. Among matrices studied, the lowest laser power was needed to acquire carbohydrate signals with high signal-to-noise ratio and resolution when CNTs were used.

  12. Observing reduction of 4-nitrobenzenthiol on gold nanoparticles in situ using surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ren, Xiaoqian; Tan, Enzhong; Lang, Xiufeng; You, Tingting; Jiang, Li; Zhang, Hongyan; Yin, Penggang; Guo, Lin

    2013-09-14

    In this article, reduction of 4-nitrobenzenthiol (4-NBT) on Au nanoparticles (NPs) was characterized using surface-enhanced Raman scattering (SERS). Plasmon-driven chemical transformation from 4-NBT dimering into p,p'-dimercaptoazobenzene (DMAB) has been investigated on the surface of Au NPs. The laser power-dependent SERS spectra of 4-NBT on the surface of Au substrates were studied, and show that the laser power has an influence on the SERS signals of 4-NBT on Au NPs and production of DMAB by a plasmon-driven surface-catalyzed chemical reaction tends to be much easier under relative high laser power. Furthermore, we have used simple and efficient Au substrates (gold NPs with a size around 45 nm) exhibiting both catalytic properties and SERS activities to monitor the catalytic reaction of surface catalytic reaction process with borohydride solution. The experiments prove that the nitro-to-amino group conversion could be completed by borohydride at ambient conditions on Au substrates. Illuminated with high laser power, 4-NBT molecules and already formed DMAB molecules are further reduced into 4-aminobenzenthiol (4-ABT) by the addition of borohydride, While with low laser power 4-NBT molecules are transformed into 4-ABT with DMAB as the intermediate, which proves Au NPs are a mild and promising catalyst. Our studies might be helpful in extending the understanding of chemical reactions of 4-NBT and related research as well as providing a new strategy synthesis of azo dyes and anilines.

  13. INFRARED MATRIX-ASSISTED LASER DESORPTION ELECTROSPRAY IONIZATION (IR-MALDESI) IMAGING SOURCE COUPLED TO A FT-ICR MASS SPECTROMETER

    Science.gov (United States)

    Robichaud, Guillaume; Barry, Jeremy A.; Garrard, Kenneth P.; Muddiman, David C.

    2013-01-01

    Mass spectrometry imaging (MSI) allows for the direct monitoring of the abundance and spatial distribution of chemical compounds over the surface of a tissue sample. This technology has opened the field of mass spectrometry to numerous innovative applications over the past 15 years. First used with SIMS and MALDI MS that operate under vacuum, interest has grown for mass spectrometry ionization sources that allow for effective imaging but where the analysis can be performed at ambient pressure with minimal or no sample preparation. We introduce here a versatile source for MALDESI imaging analysis coupled to a hybrid LTQ-FT-ICR mass spectrometer. The imaging source offers single shot or multi-shot capability per pixel with full control over the laser repetition rate and mass spectrometer scanning cycle. Scanning rates can be as fast as 1 pixel/second and a spatial resolution of 45 μm was achieved with oversampling. PMID:23208743

  14. Raman and surface enhanced Raman spectroscopic investigation on Lamiaceae plants

    Science.gov (United States)

    Rösch, P.; Popp, J.; Kiefer, W.

    1999-05-01

    The essential oils of Thymus vulgaris and Origanum vulgaris are studied by means of micro-Raman spectroscopy. The containing monoterpenes can be identified by their Raman spectra. Further the essential oils are investigated in their natural environment, the so-called oil cells of these Lamiaceae plants, with surface enhanced Raman spectroscopy (SERS). This method has the advantage to enhance Raman signals and furthermore the SERS effect leads to fluorescence quenching.

  15. Surface enhanced Raman scattering by organic and inorganic semiconductors formed on laterally ordered arrays of Au nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Milekhin, Alexander G., E-mail: milekhin@thermo.isp.nsc.ru [A.V. Rzhanov Institute of Semiconductor Physics, Lavrentiev av. 13, 630090, Novosibirsk (Russian Federation); Novosibirsk State University, Pirogov str. 2, 630090, Novosibirsk (Russian Federation); Yeryukov, Nikolay A., E-mail: yeryukov@isp.nsc.ru [A.V. Rzhanov Institute of Semiconductor Physics, Lavrentiev av. 13, 630090, Novosibirsk (Russian Federation); Sveshnikova, Larisa L.; Duda, Tatyana A.; Rodyakina, Ekaterina E. [A.V. Rzhanov Institute of Semiconductor Physics, Lavrentiev av. 13, 630090, Novosibirsk (Russian Federation); Sheremet, Evgeniya S.; Ludemann, Michael; Gordan, Ovidiu D. [Semiconductor Physics, Chemnitz University of Technology, D-09107, Chemnitz (Germany); Latyshev, Alexander V. [A.V. Rzhanov Institute of Semiconductor Physics, Lavrentiev av. 13, 630090, Novosibirsk (Russian Federation); Novosibirsk State University, Pirogov str. 2, 630090, Novosibirsk (Russian Federation); Zahn, Dietrich R.T. [Semiconductor Physics, Chemnitz University of Technology, D-09107, Chemnitz (Germany)

    2013-09-30

    This work is devoted to the investigation of surface-enhanced Raman scattering by vibrational modes of cobalt phthalocyanine ultrathin films and CuS nanocrystals prepared using by organic molecular beam vapor deposition and the Langmuir–Blodgett technique, respectively, on laterally ordered arrays of Au nanoclusters formed by electron beam lithography on Si and GaAs substrates. The surface-enhanced Raman scattering study of cobalt phthalocyanine films demonstrates the strong dependence of Raman intensity of vibrational modes in cobalt phthalocyanine on the laser excitation wavelength as well as on the size and period of Au nanoclusters. By tuning the optical resonance conditions a maximal enhancement factor of 2 × 10{sup 4} is achieved. The investigation of surface-enhanced Raman scattering by cobalt phthalocyanine deposited on laterally ordered arrays of paired Au nanoclusters (dimers) reveals anisotropic enhancement with respect to polarization of the scattered light parallel or perpendicular to the dimer axis. - Highlights: • Controllable and reproducible Au nanocluster and dimer arrays were fabricated. • Surface enhanced Raman scattering (SERS) by CuS nanocrystals was observed. • SERS by ultrathin cobalt phthalocyanine (CoPc) films was observed. • Dependence of SERS enhancement factor on the size of Au nanoclusters is resonant. • SERS by ultrathin CoPc films formed on Au dimer arrays is polarization dependent.

  16. Sample metallization for performance improvement in desorption/ionization of kilodalton molecules: quantitative evaluation, imaging secondary ion MS, and laser ablation.

    Science.gov (United States)

    Delcorte, A; Bour, J; Aubriet, F; Muller, J-F; Bertrand, P

    2003-12-15

    The metallization procedure, proposed recently for signal improvement in organic secondary ion mass spectrometry (SIMS) (Delcorte, A.; Médard, N.; Bertrand, P. Anal.Chem. 2002, 74, 4955)., has been thoroughly tested for a set of kilodalton molecules bearing various functional groups: Irganox 1010, polystyrene, polyalanine, and copper phthalocyanine. In addition to gold, we evaluate the effect of silver evaporation as a sample treatment prior to static SIMS analysis. Ion yields, damage cross sections, and emission efficiencies are compared for Ag- and Au-metallized molecular films, pristine coatings on silicon, and submonolayers of the same molecules adsorbed on silver and gold. The results are sample-dependent but as an example, the yield enhancement calculated for metallized Irganox films with respect to untreated coatings is larger than 2 orders of magnitude for the quasimolecular ion and a factor of 1-10 for characteristic fragments. Insights into the emission processes of quasimolecular ions from metallized surfaces are deduced from kinetic energy distribution measurements. The advantage of the method for imaging SIMS applications is illustrated by the study of a nonuniform coating of polystyrene oligomers on a 100-microm polypropylene film. The evaporated metal eliminates sample charging and allows us to obtain enhanced quality images of characteristic fragment ions as well as reasonably contrasted chemical mappings for cationized PS oligomers and large PP chain segments. Finally, we report on the benefit of using metal evaporation as a sample preparation procedure for laser ablation mass spectrometry. Our results show that the fingerprint spectra of Au-covered polystyrene, polypropylene, and Irganox films can be readily obtained under 337-nm irradiation, a wavelength for which the absorption of polyolefins is low. This is probably because the gold clusters embedded in the sample surface absorb and transfer the photon energy to the surrounding organic medium.

  17. Universal protocol for the rapid automated detection of carbapenem-resistant Gram-negative bacilli directly from blood cultures by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS).

    Science.gov (United States)

    Oviaño, Marina; Sparbier, Katrin; Barba, Maria José; Kostrzewa, Markus; Bou, Germán

    2016-12-01

    Detection of carbapenemase-producing bacteria directly from blood cultures is a major challenge, as patients with bacteraemia are critically ill. Early detection can be helpful for selection of the most appropriate antibiotic therapy as well as adequate control of outbreaks. In the current study, a novel matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF)-based method was developed for the rapid, automated detection of carbapenemase-producing Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii directly from blood cultures. Carbapenemase activity was determined in 30 min by measuring hydrolysis of imipenem (0.31 mg/mL) in blood cultures spiked with a series of 119 previously characterised isolates, 81 of which carried a carbapenemase enzyme (10 bla KPC , 10 bla VIM , 10 bla NDM , 10 bla IMP , 26 bla OXA-48-type , 9 bla OXA-23 , 1 bla OXA-237 , 3 bla OXA-24 and 2 bla OXA-58 ) . Twenty blood cultures obtained from bacteraemic patients carrying bla OXA-48 -producing isolates were also analysed using the same protocol. Analysis was performed using MALDI-TOF Biotyper ® Compass software, which automatically provides a result of sensitivity or resistance, calculated as the logRQ or ratio of hydrolysis of the antibiotic. This assay is simple to perform, inexpensive, time saving, universal for Gram-negative bacilli, and highly reliable (overall sensitivity and specificity of 98% and 100%, respectively). Moreover, the protocol could be established as a standardised method in clinical laboratories as it does not require specialised training in mass spectrometry. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  18. Evaluation of the Bruker Biotyper and Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry systems for identification of nonfermenting gram-negative bacilli isolated from cultures from cystic fibrosis patients.

    Science.gov (United States)

    Marko, Daniel C; Saffert, Ryan T; Cunningham, Scott A; Hyman, Jay; Walsh, John; Arbefeville, Sophie; Howard, Wanita; Pruessner, Jon; Safwat, Nedal; Cockerill, Franklin R; Bossler, Aaron D; Patel, Robin; Richter, Sandra S

    2012-06-01

    The Bruker Biotyper and Vitek MS matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) instruments were evaluated for the identification of nonfermenting gram-negative bacilli (NFGNB) by a blinded comparison to conventional biochemical or molecular methods. Two hundred NFGNB that were recovered from cultures from cystic fibrosis patients in the University of Iowa Health Care (UIHC) Microbiology Laboratory between 1 January 2006 and 31 October 2010 were sent to Mayo Clinic for analysis with the Bruker Biotyper (software version 3.0) and to bioMérieux for testing with Vitek MS (SARAMIS database version 3.62). If two attempts at direct colony testing failed to provide an acceptable MALDI-TOF identification, an extraction procedure was performed. The MS identifications from both of these systems were provided to UIHC for comparison to the biochemical or molecular identification that had been reported in the patient record. Isolates with discordant results were analyzed by 16S rRNA gene sequencing at UIHC. After discrepancy testing, the Bruker Biotyper result agreed with the biochemical or molecular method, with 72.5% of isolates to the species level, 5.5% to the complex level, and 19% to the genus level (3% not identified). The level of agreement for Vitek MS was 80% species, 3.5% complex, 6% genus, and 3.5% family (7% not identified). Both MS systems provided rapid (≤3 min per isolate) and reliable identifications. The agreement of combined species/complex/genus-level identification with the reference method was higher for the Bruker Biotyper (97% versus 89.5%, P = 0.004) but required an extraction step more often. Species-level agreement with the reference method was similar for both MS systems (72.5% and 80%, P = 0.099).

  19. Optimization of routine identification of clinically relevant Gram-negative bacteria by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry and the Bruker Biotyper.

    Science.gov (United States)

    Ford, Bradley A; Burnham, Carey-Ann D

    2013-05-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) might complement and one day replace phenotypic identification of bacteria in the clinical microbiology laboratory, but there is no consensus standard regarding the requirements for its validation prior to clinical use in the United States. The objective of this study was to assess the preanalytical variables influencing Gram-negative identification by use of the Bruker Biotyper MALDI-TOF MS system, including density of organism spotting on a stainless steel target plate and the direct overlay of organisms with formic acid. A heavy smear with formic acid overlay was either superior or equivalent to alternative smear conditions. Microbiological preanalytical variables were also assayed, such as culture medium, growth temperature, and use of serial subculture. Postanalytical analysis included the application of modified species-level identification acceptance criteria. Biotyper identifications were compared with those using traditional phenotypic methods, and discrepancies were resolved with 16S rRNA gene sequencing. Compared to the recommended score cutoffs of the manufacturer, the application of optimized Biotyper score cutoffs for species-level identification increased the rate of identification by 6.75% for the enteric Gram-negative bacteria and 4.25% for the nonfermenting Gram-negative bacteria. Various incubation temperatures, growth medium types, and repeat subcultures did not result in misidentification. We conclude that the Bruker MALDI Biotyper is a robust system for the identification of Gram-negative organisms in the clinical laboratory and that meaningful performance improvements can be made by implementing simple pre- and postanalytical techniques.

  20. Species level identification of coagulase negative Staphylococcus spp. from buffalo using matrix-assisted laser desorption ionization-time of flight mass spectrometry and cydB real-time quantitative PCR.

    Science.gov (United States)

    Pizauro, Lucas J L; de Almeida, Camila C; Soltes, Glenn A; Slavic, Durda; Rossi-Junior, Oswaldo D; de Ávila, Fernando A; Zafalon, Luiz F; MacInnes, Janet I

    2017-05-01

    Incorrect identification of Staphylococcus spp. can have serious clinical and zoonotic repercussions. Accordingly, the aim of this study was to determine if matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and/or cydB real- time quantitative PCR (qPCR) could be used to accurately identify coagulase negative Staphylococcus spp. (CoNS) obtained from buffalo milk and milking environment samples. Seventy-five of 84 CoNS isolates could be identified to the species level (score value >1.99) using MALDI-TOF MS. However, as determined by cytochrome d ubiquinol oxidase subunit II (cydB) qPCR and by 16S RNA and cydB gene sequencing, 10S. agnetis strains were wrongly identified as S. hyicus by MALDI-TOF MS. In addition, 9 isolates identified by MALDI-TOF only to the genus level (score values between 1.70 and 1.99) could be identified to species by cydB qPCR. Our findings suggest that MALDI-TOF MS is a reliable method for rapid identification of S. chromogenes and S. epidermidis (species of interest both in human and veterinary medicine) and may be able to correctly identify other Staphylococcus spp. However, at present not all Staphylococcus spp. found in buffalo milk can be accurately identified by MALDI-TOF MS and for these organisms, the cydB qPCR developed in the current study may provide a reliable alternative method for rapid identification of CoNS species. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Identification and comparative proteomic study of quail and duck egg white protein using 2-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry analysis.

    Science.gov (United States)

    Hu, S; Qiu, N; Liu, Y; Zhao, H; Gao, D; Song, R; Ma, M

    2016-05-01

    A proteomic study of egg white proteins from 2 major poultry species, namely quail (Coturnix coturnix) and duck (Anas platyrhynchos), was performed with comparison to those of chicken (Gallus gallus) through 2-dimensional polyacrylamide gel electrophoresis (2-DE) analysis. By using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS), 29 protein spots representing 10 different kinds of proteins as well as 17 protein spots designating 9 proteins were successfully identified in quail and duck egg white, respectively. This report suggested a closer relationship between quail and chicken egg white proteome patterns, whereas the duck egg white protein distribution on the 2-DE map was more distinct. In duck egg white, some well-known major proteins, such as ovomucoid, clusterin, extracellular fatty acid-binding protein precursor (ex-FABP), and prostaglandin D2 synthase (PG D2 synthase), were not detected, while two major protein spots identified as "deleted in malignant brain tumors 1" protein (DMBT1) and vitellogenin-2 were found specific to duck in the corresponding range on the 2-DE gel map. These interspecies diversities may be associated with the egg white protein functions in cell defense or regulating/supporting the embryonic development to adapt to the inhabiting environment or reproduction demand during long-term evolution. The findings of this work will give insight into the advantages involved in the application on egg white proteins from various egg sources, which may present novel beneficial properties in the food industry or related to human health. © 2016 Poultry Science Association Inc.

  2. Rapid discrimination of Haemophilus influenzae, H. parainfluenzae, and H. haemolyticus by fluorescence in situ hybridization (FISH) and two matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS) platforms.

    Science.gov (United States)

    Frickmann, Hagen; Christner, Martin; Donat, Martina; Berger, Anja; Essig, Andreas; Podbielski, Andreas; Hagen, Ralf Matthias; Poppert, Sven

    2013-01-01

    Due to considerable differences in pathogenicity, Haemophilus influenzae, H. parainfluenzae and H. haemolyticus have to be reliably discriminated in routine diagnostics. Retrospective analyses suggest frequent misidentifications of commensal H. haemolyticus as H. influenzae. In a multi-center approach, we assessed the suitability of fluorescence in situ hybridization (FISH) and matrix-assisted laser-desorption-ionization time-of-flight mass-spectrometry (MALDI-TOF-MS) for the identification of H. influenzae, H. parainfluenzae and H. haemolyticus to species level. A strain collection of 84 Haemophilus spp. comprising 50 H. influenzae, 25 H. parainfluenzae, 7 H. haemolyticus, and 2 H. parahaemolyticus including 77 clinical isolates was analyzed by FISH with newly designed DNA probes, and two different MALDI-TOF-MS systems (Bruker, Shimadzu) with and without prior formic acid extraction. Among the 84 Haemophilus strains analyzed, FISH led to 71 correct results (85%), 13 uninterpretable results (15%), and no misidentifications. Shimadzu MALDI-TOF-MS resulted in 59 correct identifications (70%), 19 uninterpretable results (23%), and 6 misidentifications (7%), using colony material applied directly. Bruker MALDI-TOF-MS with prior formic acid extraction led to 74 correct results (88%), 4 uninterpretable results (5%) and 6 misidentifications (7%). The Bruker MALDI-TOF-MS misidentifications could be resolved by the addition of a suitable H. haemolyticus reference spectrum to the system's database. In conclusion, no analyzed diagnostic procedure was free of errors. Diagnostic results have to be interpreted carefully and alternative tests should be applied in case of ambiguous test results on isolates from seriously ill patients.

  3. Thymol treatment of bacteria prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis aids in identifying certain bacteria at the subspecies level.

    Science.gov (United States)

    Holland, Ricky D; Wilkes, Jon G; Cooper, Willie M; Alusta, Pierre; Williams, Anna; Pearce, Bruce; Beaudoin, Michael; Buzatu, Dan

    2014-12-15

    The identification of bacteria based on mass spectra produced by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has become routine since its introduction in 1996. The major drawback is that bacterial patterns produced by MALDI are dependent on sample preparation prior to analysis. This results in poor reproducibility in identifying bacterial types and between laboratories. The need for a more broadly applicable and useful sample handling procedure is warranted. Thymol was added to the suspension solvent of bacteria prior to MALDI analysis. The suspension solvent consisted of ethanol, water and TFA. The bacterium was added to the thymol suspension solvent and heated. An aliquot of the bacterial suspension was mixed directly with the matrix solution at a 9:1 ratio, matrix/bacteria solution, respectively. The mixture was then placed on the MALDI plate and allowed to air dry before MALDI analysis. The thymol method improved the quality of spectra and number of peaks when compared to other sample preparation procedures studied. The bacterium-identifying biomarkers assigned to four strains of E. coli were statistically 95% reproducible analyzed on three separate days. The thymol method successfully differentiated between the four E. coli strains. In addition, the thymol procedure could identify nine out of ten S. enterica serovars over a 3-day period and nine S. Typhimurium strains from the other ten serovars 90% of the time over the same period. The thymol method can identify certain bacteria at the sub-species level and yield reproducible results over time. It improves the quality of spectra by increasing the number of peaks when compared to the other sample preparation methods assessed in this study. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA.

  4. Analysis of phloem protein patterns from different organs of Cucurbita maxima Duch. by matrix-assisted laser desorption/ionization time of flight mass spectroscopy combined with sodium dodecyl sulfate polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Kehr, J; Haebel, S; Blechschmidt-Schneider, S; Willmitzer, L; Steup, M; Fisahn, J

    1999-02-01

    Sieve tubes mediate the long-distance transport of nutrients and signals between source and sink organs of plants. To detect mobile phloem proteins that are differentially distributed in source and sink organs of Cucurbita maxima, we used both one-dimensional gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Both techniques revealed that phloem protein patterns depend on the sampling site: whilst several proteins were consistently observed in all phloem samples studied others appeared to occur in a organ-specific manner. For a characterization and identification of distinct phloem polypeptides, two approaches were chosen. First, protein bands resolved by SDS-PAGE were eluted from the polyacrylamide gel and the masses of the proteins were then determined by MALDI-TOF MS. Second, proteins resolved by SDS-PAGE were subjected to proteolytic degradation and the resulting peptides were analyzed by MALDI-TOF MS: the masses of the proteolytic peptides were used for a database search. By the latter approach, three mobile phloem compounds were identified as the phloem-specific protein PP2 (D.E. Bostwick et al., 1992, The Plant Cell 4, 1539-1548) a chymotrypsin and an aspartic proteinase inhibitor. None of the other polypeptides studied corresponded to any of the protein sequences present in the database. Furthermore, MALDI-TOF MS analyses indicated that some of the mobile phloem proteins occur in a covalently modified form and that the extent of the modification depends upon the plant organ.

  5. Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: Effect of sample preparation on MALDI-MS of synthetic polymers.

    Science.gov (United States)

    Kooijman, Pieter C; Kok, Sander; Honing, Maarten

    2017-02-28

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides detailed and in-depth information about the molecular characteristics of synthetic polymers. To obtain the most accurate results the sample preparation parameters should be chosen to suit the sample and the aim of the experiment. Because the underlying principles of MALDI are still not fully known, a priori determination of optimal sample preparation protocols is often not possible. Employing an automated sample preparation quality assessment method recently presented by us we quantified the sample preparation quality obtained using various sample preparation protocols. Six conventional matrices with and without added potassium as a cationization agent and six ionic liquid matrices (ILMs) were assessed using poly(ethylene glycol) (PEG), polytetrahydrofuran (PTHF) and poly(methyl methacrylate) (PMMA) as samples. All sample preparation protocols were scored and ranked based on predefined quality parameters and spot-to-spot repeatability. Clearly distinctive preferences were observed in matrix identity and cationization agent for PEG, PTHF and PMMA, as the addition of an excess of potassium cationization agent results in an increased score for PMMA and a contrasting matrix-dependent effect for PTHF and PEG. The addition of excess cationization agent to sample mixtures dissipates any overrepresentation of high molecular weight polymer species. Our results show reduced ionization efficiency and similar sample deposit homogeneity for all tested ILMs, compared with well-performing conventional MALDI matrices. The results published here represent a start in the unsupervised quantification of sample preparation quality for MALDI samples. This method can select the best sample preparation parameters for any synthetic polymer sample and the results can be used to formulate hypotheses on MALDI principles. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Rapid Differentiation of Haemophilus influenzae and Haemophilus haemolyticus by Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry with ClinProTools Mass Spectrum Analysis.

    Science.gov (United States)

    Chen, Jonathan H K; Cheng, Vincent C C; Wong, Chun-Pong; Wong, Sally C Y; Yam, Wing-Cheong; Yuen, Kwok-Yung

    2017-09-01

    Haemophilus influenzae is associated with severe invasive disease, while Haemophilus haemolyticus is considered part of the commensal flora in the human respiratory tract. Although the addition of a custom mass spectrum library into the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system could improve identification of these two species, the establishment of such a custom database is technically complicated and requires a large amount of resources, which most clinical laboratories cannot afford. In this study, we developed a mass spectrum analysis model with 7 mass peak biomarkers for the identification of H. influenzae and H. haemolyticus using the ClinProTools software. We evaluated the diagnostic performance of this model using 408 H. influenzae and H. haemolyticus isolates from clinical respiratory specimens from 363 hospitalized patients and compared the identification results with those obtained with the Bruker IVD MALDI Biotyper. The IVD MALDI Biotyper identified only 86.9% of H. influenzae (311/358) and 98.0% of H. haemolyticus (49/50) clinical isolates to the species level. In comparison, the ClinProTools mass spectrum model could identify 100% of H. influenzae (358/358) and H. haemolyticus (50/50) clinical strains to the species level and significantly improved the species identification rate (McNemar's test, P mass spectrometry to handle closely related bacterial species when the proprietary spectrum library failed. This approach should be useful for the differentiation of other closely related bacterial species. Copyright © 2017 American Society for Microbiology.

  7. In search of ancient biomarkers: Using femtosecond - Laser Desorption Post Ionization - Mass Spectrometry (fs-LDPI-MS) to map organic compounds within ca. 2.7 Ga samples from the Abitibi greenstone belt, Ontario, Canada

    Science.gov (United States)

    Pasterski, M. J.; Barry, G.; Hanley, L.; Kenig, F. P. H.

    2016-12-01

    One of the major challenges within the field of organic geochemistry is to determine whether an observed biomarker signature was emplaced during sedimentation (indigenous), after sedimentation via the post-depositional migration of fluids (non-indigenous), or during sampling, storage, or analysis (contaminant). Current geochemical techniques (e.g. gas chromatography-mass spectrometry, GC-MS and GCxGC-MS) can effectively determine the composition and structure of the organic constituents of a sample. However, because of the multiple preparatory steps necessary prior to GC-MS analysis (sample crushing, solvent extraction, organic fraction separation) it is impossible to precisely determine the spatial relationship between the host sample and the organic molecules within. We used an MS imaging method developed by Prof. Luke Hanley at the University of Illinois at Chicago, femtosecond-laser desorption post ionization-MS (fs-LDPI-MS), to map the organics within previously characterized ca.2.7 billion year old (Ga) metasediments from the Abitibi greenstone belt near Timmins, ON, Canada. We then compared the MS images to petrographic observations that displayed the distribution of mineral species with well constrained mineralization ages as well as fluid inclusions within the samples. Fluid inclusions are formed during mineralization and have the ability to remain intact over long timescales (up to billions of years), protecting the fluids inside from the introduction of non-indigenous and contaminant biomarkers. Although migrating post-depositional fluids can remineralize sediments, fluid inclusions associated with secondary additions are focused along grain boundaries and microfractures (secondary inclusions), thus, inclusions which are located within grain boundaries can be considered primary and the age of their formation can be determined relative to the host rock. Preliminary results indicate that previously observed biomarkers may be linked to a series of

  8. Source-identifying biomarker ions between environmental and clinical Burkholderia pseudomallei using whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Niyompanich, Suthamat; Jaresitthikunchai, Janthima; Srisanga, Kitima; Roytrakul, Sittiruk; Tungpradabkul, Sumalee

    2014-01-01

    Burkholderia pseudomallei is the causative agent of melioidosis, which is an endemic disease in Northeast Thailand and Northern Australia. Environmental reservoirs, including wet soils and muddy water, serve as the major sources for contributing bacterial infection to both humans and animals. The whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (whole-cell MALDI-TOF MS) has recently been applied as a rapid, accurate, and high-throughput tool for clinical diagnosis and microbiological research. In this present study, we employed a whole-cell MALDI-TOF MS approach for assessing its potency in clustering a total of 11 different B. pseudomallei isolates (consisting of 5 environmental and 6 clinical isolates) with respect to their origins and to further investigate the source-identifying biomarker ions belonging to each bacterial group. The cluster analysis demonstrated that six out of eleven isolates were grouped correctly to their sources. Our results revealed a total of ten source-identifying biomarker ions, which exhibited statistically significant differences in peak intensity between average environmental and clinical mass spectra using ClinProTools software. Six out of ten mass ions were assigned as environmental-identifying biomarker ions (EIBIs), including, m/z 4,056, 4,214, 5,814, 7,545, 7,895, and 8,112, whereas the remaining four mass ions were defined as clinical-identifying biomarker ions (CIBIs) consisting of m/z 3,658, 6,322, 7,035, and 7,984. Hence, our findings represented, for the first time, the source-specific biomarkers of environmental and clinical B. pseudomallei.

  9. On the interaction of peptides with calcium ions as studied by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry: towards peptide fishing using metal ion baits.

    Science.gov (United States)

    Jobst, Karl J; Terlouw, Johan K; Luider, Theo M; Burgers, Peter C

    2008-10-03

    In a previous report [J.W. de Beukelaar, J.W. Gratama, P.A. Sillevis Smitt, G.M. Verjans, J. Kraan, Th.M. Luider, P.C. Burgers, Rapid Commun. Mass Spectrom. 21 (2007) 1282] on the quality assessment of synthetic peptides used in protein-spanning peptide pools by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) we noted that certain peptides showed remarkably intense signals for their calcium-containing analogues. Here we report on a detailed mass spectrometric study of the unimolecular chemistry of these calcium-containing peptides. By integration of the experimental findings with computational results derived from DFT and the CBS-QB3 model chemistry, we have traced the processes induced by Ca(2+) attachment in the peptide ions. Key to our analysis is the observation that all of the studied calcium-bound peptides containing a threonine or serine residue show prominent losses of CH(3)CHO (from threonine) and/or CH(2)O (from serine) in both the positive and the negative ion mode. In the first step, Ca(2+) attaches itself to a negatively charged in-chain carboxylate group. Next, electrophilic attack of the calcium ion on the CH(R)OH group of threonine (RCH(3)) or serine (RH) releases the hydroxyl proton which can then move to a suitable acceptor site, viz. a peptide bond. This leads to the formation of a very stable ionic bidentate structure. Upon collisional activation (MS/MS), this bidentate opens up leading to the loss of the exposed acetaldehyde or formaldehyde molecule, to yield another bidentate structure. MS/MS spectra of selected peptides interacting with other metal ions have also been investigated and it is found that only divalent ions follow the Ca(2+)-induced transformations.

  10. Evaluation of laser diode thermal desorption (LDTD) coupled with tandem mass spectrometry (MS/MS) for support of in vitro drug discovery assays: increasing scope, robustness and throughput of the LDTD technique for use with chemically diverse compound libraries.

    Science.gov (United States)

    Beattie, Iain; Smith, Aaron; Weston, Daniel J; White, Peter; Szwandt, Simon; Sealey, Laura

    2012-02-05

    Within the drug discovery environment, the key process in optimising the chemistry of a structural series toward a potential drug candidate is the design, make and test cycle, in which the primary screens consist of a number of in vitro assays, including metabolic stability, cytochrome P450 inhibition, and time-dependent inhibition assays. These assays are often carried out using multiple drug compounds with chemically diverse structural features, often in a 96 well-plate format for maximum time-efficiency, and are supported using rapid liquid chromatographic (LC) sample introduction with a tandem mass spectrometry (MS/MS) selected reaction monitoring (SRM) endpoint, taking around 6.5 h per plate. To provide a faster time-to-decision at this critical point, there exists a requirement for higher sample throughput and a robust, well-characterized analytical alternative. This paper presents a detailed evaluation of laser diode thermal desorption (LDTD), a relatively new ambient sample ionization technique, for compound screening assays. By systematic modification of typical LDTD instrumentation and workflow, and providing deeper understanding around overcoming a number of key issues, this work establishes LDTD as a practical, rapid alternative to conventional LC-MS/MS in drug discovery, without need for extensive sample preparation or expensive, scope-limiting internal standards. Analysis of both the five and three cytochrome P450 competitive inhibition assay samples by LDTD gave improved sample throughput (0.75 h per plate) and provided comparable data quality as the IC₅₀ values obtained were within 3 fold of those calculated from the LC-MS/MS data. Additionally when applied generically to a chemically diverse library of over 250 proprietary compounds from the AstraZeneca design, make and test cycle, LDTD demonstrated a success rate of 98%. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. A clean-up technology for the simultaneous determination of lysophosphatidic acid and sphingosine-1-phosphate by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using a phosphate-capture molecule, Phos-tag.

    Science.gov (United States)

    Morishige, Jun-ichi; Urikura, Mai; Takagi, Haruko; Hirano, Kaoru; Koike, Tohru; Tanaka, Tamotsu; Satouchi, Kiyoshi

    2010-04-15

    Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are growth factor-like lipids having a phosphate group. The concentrations of these mediator lipids in blood are considered to be potential biomarkers for early detection of cancer or vascular diseases. Here, we report a method for simultaneous determination of LPA and S1P using Phos-tag, a zinc complex that specifically binds to a phosphate-monoester group. Although both LPA and S1P are hydrophilic compounds, we found that they acquire hydrophobic properties when they form complexes with Phos-tag. Based on this finding, we developed a method for the enrichment of LPA and S1P from biological samples. The first partition in a two-phase solvent system consisting of chloroform/methanol/water (1:1:0.9, v/v/v) is conducted for the removal of lipids. LPA and S1P are specifically extracted as Phos-tag complexes at the second partition by adding Phos-tag. The Phos-tag complexes of LPA and S1P are detectable by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and quantifiable based on the relative intensities of ions using 17:0 LPA and C17 S1P as internal standards. The protocol was validated by analyses of these mediator lipids in calf serum, a rat brain and a lung. The clean-up protocol is rapid, requires neither thin-layer chromatography (TLC) nor liquid chromatography (LC), and is applicable to both blood and solid tissue samples. We believe that our protocol will be useful for a routine analysis of LPA and S1P in many clinical samples. 2010 John Wiley & Sons, Ltd.

  12. Comparative proteomic analysis of hen egg white proteins during early phase of embryonic development by combinatorial peptide ligand library and matrix-assisted laser desorption ionization-time of flight.

    Science.gov (United States)

    Liu, Yijun; Qiu, Ning; Ma, Meihu

    2013-07-01

    Little is known regarding the diversification of relative low-abundance proteins in hen egg white that underlie the process of chicken embryonic development. The purpose of this study was to identify changes that may be involved in the development of chick embryos. Comparative proteomic analysis was conducive to revealing the potential biological function of low-abundance proteins and embryonic development demand. In addition, those proteins that are increased in abundance seem to have advantages to be targeted as new biomarkers for animal disease or animal production. However, the huge disparity in abundance in chicken egg white and poor performance of affinity depletion methods were specific challenges. This study applied combinatorial peptide ligand library for expanding the deep proteomics. Two-dimensional gel electrophoresis (2-DE) was performed with the hen embryo egg white, which was obtained from embryos at d 0 and 7. The protein spots showing significant increases were selected for identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry/mass spectrometry (2 mass analyzers for tandem mass spectrometry). Many precursors were identified as strongly increased after 7 d of incubation. They were ovoinhibitor precursor, clusterin precursor, apolipoprotein D precursor, and extracellular fatty acid-binding protein precursor. Moreover, clusterin precursor were observed concentrated in 2 regions: one is the range of molecular weight increase and the other is the range of high pH. In addition, ovalbumin and ovotransferrin were observed in high pH area in a 2-DE map. These findings will give insight into the changes in fertilized egg white proteins during hatching and provide a better understanding of the biochemical changes in the egg development process.

  13. Use of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry for bacterial monitoring in routine analysis at a drinking water treatment plant.

    Science.gov (United States)

    Sala-Comorera, Laura; Vilaró, Carles; Galofré, Belén; Blanch, Anicet R; García-Aljaro, Cristina

    2016-10-01

    The study of bacterial communities throughout a drinking water treatment plant could provide a basic understanding of the effects of water processing that could then be used to improve the management of such plants. However, it is necessary to develop new analytical techniques that are sufficiently efficient, robust and fast for their effective and useful application in routine analysis. The aim of this study is therefore to assess the performance of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), as compared to the PhenePlate™ system, for routine analysis in a drinking water treatment plant. To this end we studied a total of 277 colonies isolated in different seasons and from different points throughout the water treatment process, including: raw water, sand filtration, ultrafiltration, reverse osmosis and chlorination. The colonies were analysed using MALDI-TOF MS by direct deposition of the cells on the plate. The colonies were also biochemically fingerprinted using the PhenePlate™ system, clustered according to their similarity and a representative strain was selected for 16S rRNA gene sequencing and API ® gallery-based identification. The use of MALDI-TOF MS was reliable compared to the PhenePlate™ system and has the advantage of being faster and relatively cheap. Bacteria typing by MALDI-TOF MS is therefore a promising method to replace conventional routine phenotypic methods for the identification of bacteria in drinking water laboratories, thanks to its robustness. The major limiting factor for MALDI-TOF MS is the lack of a suitable mass spectra database; although each laboratory can develop its own library. This methodology will provide a tracking tool for companies to use in risk management and the detection of possible failures in both the water treatment processes and the distribution network, as well as offering characterization of the intrinsic microbial populations. Copyright © 2016 Elsevier Gmb

  14. Implementation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in Routine Clinical Laboratories Improves Identification of Coagulase-Negative Staphylococci and Reveals the Pathogenic Role of Staphylococcus lugdunensis.

    Science.gov (United States)

    Argemi, Xavier; Riegel, Philippe; Lavigne, Thierry; Lefebvre, Nicolas; Grandpré, Nicolas; Hansmann, Yves; Jaulhac, Benoit; Prévost, Gilles; Schramm, Frédéric

    2015-07-01

    The use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for staphylococcal identification is now considered routine in laboratories compared with the conventional phenotypical methods previously used. We verified its microbiological relevance for identifying the main species of coagulase-negative staphylococci (CoNS) by randomly selecting 50 isolates. From 1 January 2007 to 31 August 2008, 12,479 staphylococci were isolated with phenotypic methods, of which 4,594 were identified as Staphylococcus aureus and 7,885 were coagulase negative staphylococci. Using MALDI-TOF MS from 1 January 2011 to 31 August 2012, 14,913 staphylococci were identified, with 5,066 as S. aureus and 9,847 as CoNS. MALDI-TOF MS allowed the identification of approximately 85% of the CoNS strains, whereas only 14% of the CoNS strains were identified to the species level with phenotypic methods because they were often considered contaminants. Furthermore, the use of MALDI-TOF MS revealed the occurrence of recently characterized Staphylococcus species, such as S. pettenkoferi, S. condimenti, and S. piscifermentans. Microbiological relevance analysis further revealed that some species displayed a high rate of microbiological significance, i.e., 40% of the S. lugdunensis strains included in the analysis were associated with infection risk. This retrospective microbiological study confirms the role of MALDI-TOF MS in clinical settings for the identification of staphylococci with clinical consequences. The species distribution reveals the occurrence of the recently identified species S. pettenkoferi and putative virulent species, including S. lugdunensis. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  15. Identification of Clinical Streptococcus pneumoniae Isolates among other Alpha and Nonhemolytic Streptococci by Use of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System

    Science.gov (United States)

    Segonds, Christine; Prere, Marie-Françoise; Marty, Nicole; Oswald, Eric

    2013-01-01

    Discrimination between Streptococcus pneumoniae and its close relatives of the viridans group is a common difficulty in matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry-based identification. In the present study, the performances of the Vitek MS MALDI-TOF mass spectrometry system were assessed using 334 pneumococci, 166 other S. mitis group streptococci, 184 non-S. mitis group streptococci, and 19 related alpha- and nonhemolytic aerobic Gram-positive catalase-negative coccal isolates. Pneumococci had been identified by means of optochin susceptibility and bile solubility or serotyping, and other isolates mainly by use of RapidID32 Strep strips. In case of discordant or low-discrimination results, genotypic methods were used. The sensitivity of the Vitek MS for the identification of S. pneumoniae was 99.1%, since only three bile-insoluble isolates were misidentified as Streptococcus mitis/Streptococcus oralis. Conversely, two optochin-resistant pneumococci were correctly identified (specificity, 100%). Three Streptococcus pseudopneumoniae isolates were also correctly identified. Among nonpneumococcal isolates, 90.8% (n = 335) were correctly identified to the species or subspecies level and 2.4% (n = 9) at the group level. For the remaining 25 isolates, the Vitek MS proposed a bacterial species included in the list of possible species suggested by genotypic methods, except for 4 isolates which were not identified due to the absence of the species in the database. According to our study, the Vitek MS displays performance similar to that of the optochin susceptibility test for routine identification of pneumococcal isolates. Moreover, the Vitek MS is efficient for the identification of other viridans group streptococci and related isolates, provided that the species are included in the database. PMID:23576536

  16. The Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS identification versus biochemical tests: a study with enterobacteria from a dairy cattle environment

    Directory of Open Access Journals (Sweden)

    Naiara Miranda Bento Rodrigues

    Full Text Available Abstract Mastitis adversely affects milk production and in general cows do not regain their full production levels post recovery, leading to considerable economic losses. Moreover the percentage decrease in milk production depends on the specific pathogen that caused the infection and enterobacteria are responsible for this greater reduction. Phenotypic tests are among the currently available methods used worldwide to identify enterobacteria; however they tend to misdiagnose the species despite the multiple tests carried out. On the other hand The Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS technique has been attracting attention for its precise identification of several microorganisms at species level. In the current study, 183 enterobacteria were detected in milk (n = 47 and fecal samples (n = 94 from cows, and samples from water (n = 23 and milk lines (n = 19. All these samples were collected from a farm in Rio de Janeiro with the specific purpose of presenting the MALDI-TOF MS technique as an efficient methodology to identify Enterobacteriaceae from bovine environments. The MALDI-TOF MS technique results matched the biochemical test results in 92.9% (170/183 of the enterobacteria species and the gyrB sequencing confirmed 100% of the proteomic technique results. The amino acid decarboxylation test made the most misidentifications and Enterobacter spp. was the most misidentified genus (76.9%, 10/13. These results aim to clarify the current biochemical errors in enterobacteria identification, considering isolates from a bovine environment, and show the importance for more careful readings of phenotypic tests which are often used in veterinary microbiology laboratories.

  17. Characteristics of glycation and glycation sites of lysozyme by matrix-assisted laser desorption/ionization time of flight/time-of-flight mass spectrometry and Liquid chromatography-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Ruan, Eric Dongliang; Wang, Hui; Ruan, Yuanyuan; Juáreza, Manuel

    2014-01-01

    Protein glycation with reducing sugars through the Maillard reaction is regarded as one of the most important reactions in food chem- istry. Amadori rearrangement products [ARPs] are produced at the initial stage of the Maillard reaction and then advanced glycation products may be formed. We report here that using matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight detection [MALDI-TOF-MS] and electrospray ionization mass spectrometry (ESI-MSJ to monitor the glycation process in lysozyme and the D-glucose model system. MALDI-TOF-MS displayed a heterogeneous distribution of glycation via a total mass shift in spectra. However electrospray ionization mass spectrometry [ESI-MS] data showed that a total of four molecules of glucose reacted with Lysozyme at an increase in molecular weight by a 162 Da unit. Further, we identified the glycation sites of lysozyme by using MALDI-TOF/TOF-MS and Liquid chromatography [LC]-ESI-MS/MS. Besides the two glycation sites of Lys1 and Lys97 identified by MALDI-TOF/TOF-MS, the other two glycation sites of Lys13 and Lys116 were characterized unambiguously by LC-ESI-MS/MS. Both MALDI-TOF/TOF-MS and LC-ESI-MS/ MS provided confidence in the study of the glycation by restricting the number of possible residues through (un]modified ions. The study is useful to monitor and characterize glycation in protein systems based on both MALDI-TOF-MS and ESI-MS. Comparatively, LC-ESI-MS/MS provides more fragments with better recovery for the identification of glycation than MALDI-TOF/TOF-MS.

  18. Analysis of the differentially expressed low molecular weight peptides in human serum via an N-terminal isotope labeling technique combining nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Leng, Jiapeng; Zhu, Dong; Wu, Duojiao; Zhu, Tongyu; Zhao, Ningwei; Guo, Yinlong

    2012-11-15

    Peptidomics analysis of human serum is challenging due to the low abundance of serum peptides and interference from the complex matrix. This study analyzed the differentially expressed (DE) low molecular weight peptides in human serum integrating a DMPITC-based N-terminal isotope labeling technique with nano-liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (nano-LC/MALDI-MS). The workflow introduced a [d(6)]-4,6-dimethoxypyrimidine-2-isothiocyanate (DMPITC)-labeled mixture of aliquots from test samples as the internal standard. The spiked [d(0)]-DMPITC-labeled samples were separated by nano-LC then spotted on the MALDI target. Both quantitative and qualitative studies for serum peptides were achieved based on the isotope-labeled peaks. The DMPITC labeling technique combined with nano-LC/MALDI-MS not only minimized the errors in peptide quantitation, but also allowed convenient recognition of the labeled peptides due to the 6 Da mass difference. The data showed that the entire research procedure as well as the subsequent data analysis method were effective, reproducible, and sensitive for the analysis of DE serum peptides. This study successfully established a research model for DE serum peptides using DMPITC-based N-terminal isotope labeling and nano-LC/MALDI-MS. Application of the DMPITC-based N-terminal labeling technique is expected to provide a promising tool for the investigation of peptides in vivo, especially for the analysis of DE peptides under different biological conditions. Copyright © 2012 John Wiley & Sons, Ltd.

  19. Rapid and easy detection of low-level resistance to vancomycin in methicillin-resistant Staphylococcus aureus by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Asakura, Kota; Azechi, Takuya; Sasano, Hiroshi; Matsui, Hidehito; Hanaki, Hideaki; Miyazaki, Motoyasu; Takata, Tohru; Sekine, Miwa; Takaku, Tomoiku; Ochiai, Tomonori; Komatsu, Norio; Shibayama, Keigo; Katayama, Yuki; Yahara, Koji

    2018-01-01

    Vancomycin-intermediately resistant Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) are associated with treatment failure. hVISA contains only a subpopulation of cells with increased minimal inhibitory concentrations, and its detection is problematic because it is classified as vancomycin-susceptible by standard susceptibility testing and the gold-standard method for its detection is impractical in clinical microbiology laboratories. Recently, a research group developed a machine-learning classifier to distinguish VISA and hVISA from vancomycin-susceptible S. aureus (VSSA) according to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) data. Nonetheless, the sensitivity of hVISA classification was found to be 76%, and the program was not completely automated with a graphical user interface. Here, we developed a more accurate machine-learning classifier for discrimination of hVISA from VSSA and VISA among MRSA isolates in Japanese hospitals by means of MALDI-TOF MS data. The classifier showed 99% sensitivity of hVISA classification. Furthermore, we clarified the procedures for preparing samples and obtaining MALDI-TOF MS data and developed all-in-one software, hVISA Classifier, with a graphical user interface that automates the classification and is easy for medical workers to use; it is publicly available at https://github.com/bioprojects/hVISAclassifier. This system is useful and practical for screening MRSA isolates for the hVISA phenotype in clinical microbiology laboratories and thus should improve treatment of MRSA infections.

  20. The Technical and Biological Reproducibility of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS Based Typing: Employment of Bioinformatics in a Multicenter Study.

    Directory of Open Access Journals (Sweden)

    Michael Oberle

    Full Text Available The technical, biological, and inter-center reproducibility of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF MS typing data has not yet been explored. The aim of this study is to compare typing data from multiple centers employing bioinformatics using bacterial strains from two past outbreaks and non-related strains.Participants received twelve extended spectrum betalactamase-producing E. coli isolates and followed the same standard operating procedure (SOP including a full-protein extraction protocol. All laboratories provided visually read spectra via flexAnalysis (Bruker, Germany. Raw data from each laboratory allowed calculating the technical and biological reproducibility between centers using BioNumerics (Applied Maths NV, Belgium.Technical and biological reproducibility ranged between 96.8-99.4% and 47.6-94.4%, respectively. The inter-center reproducibility showed a comparable clustering among identical isolates. Principal component analysis indicated a higher tendency to cluster within the same center. Therefore, we used a discriminant analysis, which completely separated the clusters. Next, we defined a reference center and performed a statistical analysis to identify specific peaks to identify the outbreak clusters. Finally, we used a classifier algorithm and a linear support vector machine on the determined peaks as classifier. A validation showed that within the set of the reference center, the identification of the cluster was 100% correct with a large contrast between the score with the correct cluster and the next best scoring cluster.Based on the sufficient technical and biological reproducibility of MALDI-TOF MS based spectra, detection of specific clusters is possible from spectra obtained from different centers. However, we believe that a shared SOP and a bioinformatics approach are required to make the analysis robust and reliable.

  1. Yersinia enterocolitica in Diagnostic Fecal Samples from European Dogs and Cats: Identification by Fourier Transform Infrared Spectroscopy and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    Science.gov (United States)

    Stamm, Ivonne; Hailer, Mandy; Depner, Barbara; Kopp, Peter A.

    2013-01-01

    Yersinia enterocolitica is the main cause of yersiniosis in Europe, one of the five main bacterial gastrointestinal diseases of humans. Beside pigs, companion animals, especially dogs and cats, were repeatedly discussed in the past as a possible source of pathogenic Y. enterocolitica. To investigate the presence and types of Y. enterocolitica in companion animals, a total of 4,325 diagnostic fecal samples from dogs and 2,624 samples from cats were tested. The isolates obtained were differentiated by using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and Fourier transform infrared spectroscopy (FT-IR). Isolated Y. enterocolitica strains were bioserotyped. The detection of the ail gene by PCR and confirmation by FT-IR were used as a pathogenicity marker. Y. enterocolitica strains were isolated from 198 (4.6%) of the dog and 8 (0.3%) of the cat fecal samples investigated. One hundred seventy-nine isolates from dogs were analyzed in detail. The virulence factor Ail was detected in 91.6% of isolates. Isolates of biotype 4 (54.7%) and, to a lesser extent, biotypes 2 (23.5%), 3 (11.2%), and 5 (2.2%) were detected. The remaining 8.4% of strains belonged to the ail-negative biotype 1A. All 7 isolates from cats that were investigated in detail were ail positive. These results indicate that companion animals could be a relevant reservoir for a broad range of presumptively human-pathogenic Y. enterocolitica types. MALDI-TOF MS and FT-IR proved to be valuable methods for the rapid identification of Y. enterocolitica, especially in regard to the large number of samples that were investigated in a short time frame. PMID:23284028

  2. Microscale Solubility Measurements of Matrix-Assisted Laser Desorption-Ionization (MALDI) Matrices Using Attenuated Total Reflection (ATR) Fourier Transform Infrared Spectroscopy (FT-IR) Coupled with Partial Least Squares (PLS) Analysis.

    Science.gov (United States)

    Gorre, Elsa; Owens, Kevin G

    2016-11-01

    In this work an attenuated total reflection Fourier transform infrared (FT-IR) absorption based method is used to measure the solubility of two matrix-assisted laser desorption-ionization (MALDI) matrices in a few pure solvents and mixtures of acetonitrile and water using low microliter amounts of solution. Results from a method that averages the values obtained from multiple calibration curves created by manual peak picking are compared to those predicted using a partial least squares (PLS) chemometrics approach. The PLS method provided solubility values that were in good agreement with the manual method with significantly greater ease of analysis. As a test, the solubility of adipic acid in acetone was measured using the two methods of analysis, and the values are in good agreement with solubility values reported in literature. The solubilities of the MALDI matrices α-cyano-4-hydroxy cinnamic acid (CHCA) and sinapinic acid (SA) were measured in a series of mixtures made from acetonitrile (ACN) and water; surprisingly, the results show a highly nonlinear trend. While both CHCA and SA show solubility values of less than 10 mg/mL in the pure solvents, the solubility value for SA increases to 56.3 mg/mL in a 75:25 v/v ACN:water mixture. This can have a significant effect on the matrix-to-analyte ratios in the MALDI experiment when sample protocols call for preparation of a saturated solution of the matrix in the chosen solvent system. © The Author(s) 2016.

  3. Yersinia enterocolitica in diagnostic fecal samples from European dogs and cats: identification by fourier transform infrared spectroscopy and matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    Science.gov (United States)

    Stamm, Ivonne; Hailer, Mandy; Depner, Barbara; Kopp, Peter A; Rau, Jörg

    2013-03-01

    Yersinia enterocolitica is the main cause of yersiniosis in Europe, one of the five main bacterial gastrointestinal diseases of humans. Beside pigs, companion animals, especially dogs and cats, were repeatedly discussed in the past as a possible source of pathogenic Y. enterocolitica. To investigate the presence and types of Y. enterocolitica in companion animals, a total of 4,325 diagnostic fecal samples from dogs and 2,624 samples from cats were tested. The isolates obtained were differentiated by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and Fourier transform infrared spectroscopy (FT-IR). Isolated Y. enterocolitica strains were bioserotyped. The detection of the ail gene by PCR and confirmation by FT-IR were used as a pathogenicity marker. Y. enterocolitica strains were isolated from 198 (4.6%) of the dog and 8 (0.3%) of the cat fecal samples investigated. One hundred seventy-nine isolates from dogs were analyzed in detail. The virulence factor Ail was detected in 91.6% of isolates. Isolates of biotype 4 (54.7%) and, to a lesser extent, biotypes 2 (23.5%), 3 (11.2%), and 5 (2.2%) were detected. The remaining 8.4% of strains belonged to the ail-negative biotype 1A. All 7 isolates from cats that were investigated in detail were ail positive. These results indicate that companion animals could be a relevant reservoir for a broad range of presumptively human-pathogenic Y. enterocolitica types. MALDI-TOF MS and FT-IR proved to be valuable methods for the rapid identification of Y. enterocolitica, especially in regard to the large number of samples that were investigated in a short time frame.

  4. Expression of Raf kinase inhibitor protein in human hepatoma tissues by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight methods.

    Science.gov (United States)

    Tsao, D A; Shiau, Y F; Tseng, C S; Chang, H R

    2016-01-01

    Hepatocellular carcinoma (HCC) is the most common malignant liver tumor. To reduce the mortality and improve the effectiveness of therapy, it is important to search for changes in tumor-specific biomarkers whose function may involve in disease progression and which may be useful as potential therapeutic targets. Materials and Mehtods: In this study, we use two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to observe proteome alterations of 12 tissue pairs isolated from HCC patients: Normal and tumorous tissue. Comparing the tissue types with each other, 40 protein spots corresponding to fifteen differentially expressed between normal and cancer part of HCC patients. Raf kinase inhibitor protein (RKIP), an inhibitor of Raf-mediated activation of mitogen-activated protein kinase/extracellular signal-regulated kinase, may play an important role in cancer metastasis and cell proliferation and migration of human hepatoma cells. RKIP may be considered as a marker for HCC, because its expression level changes considerably in HCC compared with normal tissue. In addition, we used the methods of Western blotting and real time-polymerase chain reaction to analysis the protein expression and gene expression of RKIP. The result showed RKIP protein and gene expression in tumor part liver tissues of HCC patient is lower than peritumorous non-neoplastic liver tissue of the corresponding HCC samples. These results strongly suggest that RKIP may be considered to be a marker for HCC and RKIP are down-regulated in liver cancer cell.

  5. Rapid discrimination of Haemophilus influenzae, H. parainfluenzae, and H. haemolyticus by fluorescence in situ hybridization (FISH and two matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS platforms.

    Directory of Open Access Journals (Sweden)

    Hagen Frickmann

    Full Text Available BACKGROUND: Due to considerable differences in pathogenicity, Haemophilus influenzae, H. parainfluenzae and H. haemolyticus have to be reliably discriminated in routine diagnostics. Retrospective analyses suggest frequent misidentifications of commensal H. haemolyticus as H. influenzae. In a multi-center approach, we assessed the suitability of fluorescence in situ hybridization (FISH and matrix-assisted laser-desorption-ionization time-of-flight mass-spectrometry (MALDI-TOF-MS for the identification of H. influenzae, H. parainfluenzae and H. haemolyticus to species level. METHODOLOGY: A strain collection of 84 Haemophilus spp. comprising 50 H. influenzae, 25 H. parainfluenzae, 7 H. haemolyticus, and 2 H. parahaemolyticus including 77 clinical isolates was analyzed by FISH with newly designed DNA probes, and two different MALDI-TOF-MS systems (Bruker, Shimadzu with and without prior formic acid extraction. PRINCIPAL FINDINGS: Among the 84 Haemophilus strains analyzed, FISH led to 71 correct results (85%, 13 uninterpretable results (15%, and no misidentifications. Shimadzu MALDI-TOF-MS resulted in 59 correct identifications (70%, 19 uninterpretable results (23%, and 6 misidentifications (7%, using colony material applied directly. Bruker MALDI-TOF-MS with prior formic acid extraction led to 74 correct results (88%, 4 uninterpretable results (5% and 6 misidentifications (7%. The Bruker MALDI-TOF-MS misidentifications could be resolved by the addition of a suitable H. haemolyticus reference spectrum to the system's database. In conclusion, no analyzed diagnostic procedure was free of errors. Diagnostic results have to be interpreted carefully and alternative tests should be applied in case of ambiguous test results on isolates from seriously ill patients.

  6. Laser ablation principles and applications

    CERN Document Server

    1994-01-01

    Laser Ablation provides a broad picture of the current understanding of laser ablation and its many applications, from the views of key contributors to the field. Discussed are in detail the electronic processes in laser ablation of semiconductors and insulators, the post-ionization of laser-desorbed biomolecules, Fourier-transform mass spectroscopy, the interaction of laser radiation with organic polymers, laser ablation and optical surface damage, laser desorption/ablation with laser detection, and laser ablation of superconducting thin films.

  7. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  8. In situ surface-enhanced Raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface.

    Science.gov (United States)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin T

    2015-03-03

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (Raman spectroelectrochemistry. The SEC system includes a nanostructured Au surface that serves dual roles as the electrochemical working electrode (WE) and SERS substrate, a microfabricated Pt counter electrode (CE), and an external Ag/AgCl reference electrode (RE). The nanostructured Au WE enables highly sensitive in situ SERS spectroscopy through large and reproducible SERS enhancements, which eliminates the need for resonant wavelength matching of the laser excitation source with the electronic absorption of the target molecule. The new SEC analysis system has the merits of wide applicability to target molecules, small sample volume, and a low detection limit. We demonstrate in situ SERS spectroelectrochemistry measurements of the metalloporphyrin hemin showing shifts of the iron oxidation marker band ν4 with the nanostructured Au working electrode under precise potential control.

  9. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  10. Ultrasensitive detection of phenolic antioxidants by surface enhanced Raman spectroscopy

    Science.gov (United States)

    Ornelas-Soto, N.; Aguilar-Hernández, I. A.; Afseth, N.; López-Luke, T.; Contreras-Torres, F. F.; Wold, J. P.

    2017-08-01

    Surface-Enhanced Raman Spectroscopy (SERS) is a powerful surface-sensitive technique to study the vibrational properties of analytes at very low concentrations. In this study, ferulic acid, p-coumaric acid, caffeic acid and sinapic acid were analyzed by SERS using Ag colloids. Analytes were detected up to 2.5x10-9M. For caffeic acid and coumaric acid, this detection limit has been reached for the first time, as well as the SERS analysis of sinapic acid using silver colloids.

  11. Surface enhanced raman spectroscopy analytical, biophysical and life science applications

    CERN Document Server

    Schlücker, Sebastian

    2013-01-01

    Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.

  12. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  13. Characterization of a Campylobacter fetus-like strain isolated from the faeces of a sick leopard tortoise (Stigmochelys pardalis) using matrix-assisted laser desorption/ionization time of flight as an alternative to bacterial 16S rDNA phylogeny.

    Science.gov (United States)

    Benejat, L; Gravet, A; Sifré, E; Ben Amor, S; Quintard, B; Mégraud, F; Lehours, P

    2014-04-01

    This article describes the isolation and characterization of a Campylobacter-like isolate originating from the faeces of a sick leopard tortoise. Molecular as well as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) characterization suggests that it could correspond to a new Campylobacter species. The major impact of this work is the demonstration that proteomics and especially MALDI-TOF typing can be used as an alternative method to 16S rDNA sequencing for phylogeny and can lead to the discovery of new Campylobacters. © 2013 The Society for Applied Microbiology.

  14. Structural elucidation of AgAsS2 glass by the analysis of clusters formed during laser desorption ionisation applying quadrupole ion trap time-of-flight mass spectrometry.

    Science.gov (United States)

    Mawale, Ravi Madhukar; Alberti, Milan; Zhang, Bo; Fraenkl, Max; Wagner, Tomas; Havel, Josef

    2016-03-15

    The structure of AgA(s)S2 glass, which has a broad range of applications, is still not well understood and a systematic mass spectrometric analysis of AgA(s)S2 glass is currently not available. Elucidation of the structure should help in the development of this material. The AgA(s)S2 glass was prepared by the melt-quenched technique. Laser desorption ionisation (LDI) using quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to follow the generation of Ag(m)As(n)S(x) clusters. The stoichiometry of the clusters generated was determined via collision-induced dissociation (CID) and modelling of isotopic patterns. The AgA(s)S2 glass was characterised by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The LDI of AgA(s)S2 glass leads to the formation of unary (Ag+/− and As(3+)) species, 38 binary (As(n)S(x), Ag(m)S(x)), and 98 ternary (Ag(m)As(n)S(x)) singly charged clusters. The formation of silver-rich nano-grains during AgA(s)S2 glass synthesis has been identified using TEM analysis and also verified by QIT-TOFMS. TOFMS was shown to be a useful technique to study the generation of Ag(m)As(n)S(x )clusters. SEM, TEM and EDX analysis proved that the structure of AgA(s)S2 glass is ‘grain-like’ where grains are either: (1) Silver-rich ‘islands’ (Ag(m,) m up to 39) connected by arsenic and/or sulfur or arsenic sulfide chains or (2) silver sulfide (Ag2S)m (m = 9-20) clusters also similarly inter-connected. This obtained structural information may be useful for the development of ultra-high-density phase-change storage and memory devices using this kind of glass as a base.

  15. Matrix-assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) as a Reliable Tool to Identify Species of Catalase-negative Gram-positive Cocci not Belonging to the Streptococcus Genus.

    Science.gov (United States)

    Almuzara, Marisa; Barberis, Claudia; Velázquez, Viviana Rojas; Ramirez, Maria Soledad; Famiglietti, Angela; Vay, Carlos

    2016-01-01

    To evaluate the performance of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) by using 190 Catalase-negative Gram-Positive Cocci (GPC) clinical isolates. All isolates were identified by conventional phenotypic tests following the proposed scheme by Ruoff and Christensen and MALDI-TOF MS (Bruker Daltonics, BD, Bremen, Germany). Two different extraction methods (direct transfer formic acid method on spot and ethanol formic acid extraction method) and different cut-offs for genus/specie level identification were used. The score cut-offs recommended by the manufacturer (≥ 2.000 for species-level, 1.700 to 1.999 for genus level and genus level, ≥ 1.700 for species-level and score genus or species. MALDI-TOF MS identification was considered correct when the result obtained from MS database agreed with the phenotypic identification result. When both methods gave discordant results, the 16S rDNA or sodA genes sequencing was considered as the gold standard identification method. The results obtained by MS concordant with genes sequencing, although discordant with conventional phenotyping, were considered correct. MS results discordant with 16S or sod A identification were considered incorrect. Using the score cut-offs recommended by the manufacturer, 97.37% and 81.05% were correctly identified to genus and species level, respectively. On the other hand, using lower cut-off scores for identification, 97.89% and 94.21% isolates were correctly identified to genus and species level respectively by MALDI-TOF MS and no significant differences between the results obtained with two extraction methods were obtained. The results obtained suggest that MALDI-TOF MS has the potential of being an accurate tool for Catalase-negative GPC identification even for those species with difficult diagnosis as Helcococcus , Abiotrophia , Granulicatella , among others. Nevertheless, expansion of the library, especially including more strains with

  16. Interlaboratory comparison of sample preparation methods, database expansions, and cutoff values for identification of yeasts by matrix-assisted laser desorption ionization-time of flight mass spectrometry using a yeast test panel.

    Science.gov (United States)

    Vlek, Anneloes; Kolecka, Anna; Khayhan, Kantarawee; Theelen, Bart; Groenewald, Marizeth; Boel, Edwin; Boekhout, Teun

    2014-08-01

    An interlaboratory study using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to determine the identification of clinically important yeasts (n = 35) was performed at 11 clinical centers, one company, and one reference center using the Bruker Daltonics MALDI Biotyper system. The optimal cutoff for the MALDI-TOF MS score was investigated using receiver operating characteristic (ROC) curve analyses. The percentages of correct identifications were compared for different sample preparation methods and different databases. Logistic regression analysis was performed to analyze the association between the number of spectra in the database and the percentage of strains that were correctly identified. A total of 5,460 MALDI-TOF MS results were obtained. Using all results, the area under the ROC curve was 0.95 (95% confidence interval [CI], 0.94 to 0.96). With a sensitivity of 0.84 and a specificity of 0.97, a cutoff value of 1.7 was considered optimal. The overall percentage of correct identifications (formic acid-ethanol extraction method, score ≥ 1.7) was 61.5% when the commercial Bruker Daltonics database (BDAL) was used, and it increased to 86.8% by using an extended BDAL supplemented with a Centraalbureau voor Schimmelcultures (CBS)-KNAW Fungal Biodiversity Centre in-house database (BDAL+CBS in-house). A greater number of main spectra (MSP) in the database was associated with a higher percentage of correct identifications (odds ratio [OR], 1.10; 95% CI, 1.05 to 1.15; P value of 1.7 for the identification of yeasts using MALDI-TOF MS. The inclusion of enough isolates of the same species in the database can enhance the proportion of correctly identified strains. Further optimization of the preparation methods, especially of the direct transfer method, may contribute to improved diagnosis of yeast-related infections. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  17. Ammonia-treated N-(1-naphthyl) ethylenediamine dihydrochloride as a novel matrix for rapid quantitative and qualitative determination of serum free fatty acids by matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yaping [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China); Wang, Yanmin [Department of Clinical Laboratory, Heze Municipal Hospital, Shandong (China); Guo, Shuai; Guo, Yumei; Liu, Hui [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China); Li, Zhili, E-mail: lizhili@ibms.pumc.edu.cn [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China)

    2013-09-10

    Graphical abstract: -- Highlights: •A novel MALDI matrix for the detection of serum free fatty acids is ammonia-treated N-(1-naphthyl) ethylenediamine dihydrochloride. •Multiple point internal standard calibration curves were constructed for nine FFAs, respectively, with excellent correlation coefficients between 0.991 and 0.999. •The MALDI-MS approach was used to rapidly differentiate the patients with and without hyperglycemia and healthy controls. -- Abstract: The blood free fatty acids (FFAs), which provide energy to the cell and act as substrates in the synthesis of fats, lipoproteins, liposaccharides, and eicosanoids, involve in a number of important physiological processes. In the present study, matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) with ammonia-treated N-(1-naphthyl) ethylenediamine dihydrochloride (ATNEDC) as a novel MALDI matrix in a negative ion mode was employed to directly quantify serum FFAs. Multiple point internal standard calibration curves between the concentration ratios of individual fatty acids to internal standard (IS, C{sub 17:0}) versus their corresponding intensity ratios were constructed for C{sub 14:0}, C{sub 16:1}, C{sub 16:0}, C{sub 18:0}, C{sub 18:1}, C{sub 18:2}, C{sub 18:3}, C{sub 20:4}, and C{sub 22:6}, respectively, in their mixture, with correlation coefficients between 0.991 and 0.999 and limits of detection (LODs) between 0.2 and 5.4 μM, along with the linear dynamic range of more than two orders of magnitude. The results indicate that the multiple point internal standard calibration could reduce the impact of ion suppression and improve quantification accuracy in the MALDI mode. The quantitative results of nine FFAs from 339 serum samples, including 161 healthy controls, 118 patients with hyperglycemia and 60 patients without hyperglycemia show that FFAs levels in hyperglycemic patient sera are significantly higher than those in healthy

  18. Nanosensors based on functionalized nanoparticles and surface enhanced raman scattering

    Science.gov (United States)

    Talley, Chad E.; Huser, Thomas R.; Hollars, Christopher W.; Lane, Stephen M.; Satcher, Jr., Joe H.; Hart, Bradley R.; Laurence, Ted A.

    2007-11-27

    Surface-Enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopic technique that utilizes metal surfaces to provide enhanced signals of several orders of magnitude. When molecules of interest are attached to designed metal nanoparticles, a SERS signal is attainable with single molecule detection limits. This provides an ultrasensitive means of detecting the presence of molecules. By using selective chemistries, metal nanoparticles can be functionalized to provide a unique signal upon analyte binding. Moreover, by using measurement techniques, such as, ratiometric received SERS spectra, such metal nanoparticles can be used to monitor dynamic processes in addition to static binding events. Accordingly, such nanoparticles can be used as nanosensors for a wide range of chemicals in fluid, gaseous and solid form, environmental sensors for pH, ion concentration, temperature, etc., and biological sensors for proteins, DNA, RNA, etc.

  19. Applications of the surface enhanced Raman scattering (SERS)

    International Nuclear Information System (INIS)

    Picquart, M.; Haro P, E.; Bernard, S.

    2007-01-01

    Full text: Vibration spectroscopy techniques are used for many times to identify substances, determine molecular structure and quantify them, independently of their physical state. Raman spectroscopy as infrared absorption permit to access the vibration energy levels of molecules. In the second case, the permanent dipolar moment is involved while in the first one it is the polarizability (and the induced dipolar moment). Unfortunately, the classical Raman spectroscopy is low sensitive in particular in the case of biological molecules. On the opposite, the surface enhanced Raman spectroscopy (SERS) offers great potentialities. In this case, the molecules are adsorbed on a rough surface or on nanoparticles of gold or silver and the: signal can be increased by a factor of 10 7 to 10 8 . Moreover, the spectral enhancement is greater for the vibrations of the functional group of the molecule adsorbed on the substrate. In this work, we present the main theoretical bases of SERS, and some results obtain on different systems. (Author)

  20. Raman and Surface-Enhanced Raman Scattering for Biofilm Characterization

    Directory of Open Access Journals (Sweden)

    Seda Keleştemur

    2018-01-01

    Full Text Available Biofilms are a communal way of living for microorganisms in which microorganism cells are surrounded by extracellular polymeric substances (EPS. Most microorganisms can live in biofilm form. Since microorganisms are everywhere, understanding biofilm structure and composition is crucial for making the world a better place to live, not only for humans but also for other living creatures. Raman spectroscopy is a nondestructive technique and provides fingerprint information about an analyte of interest. Surface-enhanced Raman spectroscopy is a form of this technique and provides enhanced scattering of the analyte that is in close vicinity of a nanostructured noble metal surface such as silver or gold. In this review, the applications of both techniques and their combination with other biofilm analysis techniques for characterization of composition and structure of biofilms are discussed.

  1. Surface-enhanced Raman spectroscopy bioanalytical, biomolecular and medical applications

    CERN Document Server

    Procházka, Marek

    2016-01-01

    This book gives an overview of recent developments in RS and SERS for sensing and biosensing considering also limitations, possibilities and prospects of this technique. Raman scattering (RS) is a widely used vibrational technique providing highly specific molecular spectral patterns. A severe limitation for the application of this spectroscopic technique lies in the low cross section of RS. Surface-enhanced Raman scattering (SERS) spectroscopy overcomes this problem by 6-11 orders of magnitude enhancement compared with the standard RS for molecules in the close vicinity of certain rough metal surfaces. Thus, SERS combines molecular fingerprint specificity with potential single-molecule sensitivity. Due to the recent development of new SERS-active substrates, labeling and derivatization chemistry as well as new instrumentations, SERS became a very promising tool for many varied applications, including bioanalytical studies and sensing. Both intrinsic and extrinsic SERS biosensing schemes have been employed to...

  2. Directional surface enhanced Raman scattering on gold nano-gratings

    International Nuclear Information System (INIS)

    Gillibert, Raymond; Yasukuni, Ryohei; Chapelle, Marc Lamy de la; Sarkar, Mitradeep; Bryche, Jean-François; Moreau, Julien; Besbes, Mondher; Canva, Michael; Barbillon, Grégory; Bartenlian, Bernard

    2016-01-01

    Directional plasmon excitation and surface enhanced Raman scattering (SERS) emission were demonstrated for 1D and 2D gold nanostructure arrays deposited on a flat gold layer. The extinction spectrum of both arrays exhibits intense resonance bands that are redshifted when the incident angle is increased. Systematic extinction analysis of different grating periods revealed that this band can be assigned to a propagated surface plasmon of the flat gold surface that fulfills the Bragg condition of the arrays (Bragg mode). Directional SERS measurements demonstrated that the SERS intensity can be improved by one order of magnitude when the Bragg mode positions are matched with either the excitation or the Raman wavelengths. Hybridized numerical calculations with the finite element method and Fourier modal method also proved the presence of the Bragg mode plasmon and illustrated that the enhanced electric field of the Bragg mode is particularly localized on the nanostructures regardless of their size. (paper)

  3. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja

    2010-01-01

    Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives...... molecules adsorbed onto the substrate. The substrates were fabricated in a cleanroom process which only requires two steps to produce well controlled nano-sized high aspect ratio metal pillars. These substrates had superior chemical sensing performance in addition to a more cost effective fabrication...... process compared to existing commercial substrates. Therefore it is believed that these novel substrates will be able to make SERS more applicable in mobile explosives detection systems to be deployed in for example landmine clearance actions....

  4. Detection of volatile organic compounds using surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chang, A S; Maiti, A; Ileri, N; Bora, M; Larson, C C; Britten, J A; Bond, T C

    2012-03-22

    The authors present the detection of volatile organic compounds directly in their vapor phase by surface-enhanced Raman scattering (SERS) substrates based on lithographically-defined two-dimensional rectangular array of nanopillars. The type of nanopillars is known as the tapered pillars. For the tapered pillars, SERS enhancement arises from the nanofocusing effect due to the sharp tip on top. SERS experiments were carried out on these substrates using various concentrations of toluene vapor. The results show that SERS signal from a toluene vapor concentration of ppm level can be achieved, and the toluene vapor can be detected within minutes of exposing the SERS substrate to the vapor. A simple adsorption model is developed which gives results matching the experimental data. The results also show promising potential for the use of these substrates in environmental monitoring of gases and vapors.

  5. Surface-Enhanced Raman Scattering in Molecular Junctions.

    Science.gov (United States)

    Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

    2017-08-18

    Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

  6. Surface-enhanced Raman scattering on gold nanotrenches and nanoholes

    KAUST Repository

    Yue, Weisheng

    2012-04-01

    Dependent effects on edge-to-edge distance and incidence polarization in surface-enhanced Raman Scattering (SERS) were studied in detection of 4-mercaptopyridine (4-MPy) molecules absorbed on gold nanotrenches and nanoholes. The gold nanostructures with controllable size and period were fabricated using electron-beam lithography. Large SERS enhancement in detection of 4-MPy molecules on both nanostructred substrates was observed. The SERS enhancement increased exponentially with decrease of edge to-edge distance for both the nanotrenches and nanoholes while keeping the sizes of the nanotrenches and nanoholes unchanged. Investigation of polarization dependence showed that the SERS enhancement of nanotrenches was much more sensitive to the incidence polarizations than that of nanoholes. © 2012 American Scientific Publishers.

  7. Detection of explosives based on surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Wackerbarth, Hainer; Salb, Christian; Gundrum, Lars; Niederkrüger, Matthias; Christou, Konstantin; Beushausen, Volker; Viöl, Wolfgang

    2010-08-10

    In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.

  8. Engineering Plasmonic Nanopillar Arrays for Surface-enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wu, Kaiyu

    This Ph.D. thesis presents (i) an in-depth understanding of the localized surface plasmon resonances (LSPRs) in the nanopillar arrays (NPs) for surface-enhanced Raman spectroscopy (SERS), and (ii) systematic ways of optimizing the fabrication process of NPs to improve their SERS efficiencies.......e., the particle mode and the cavity mode. The particle mode can be hybridized via leaning of pillars. The LSPR wavelength of the cavity mode is dominant only by the diameter of the Si pillar. The presence of a substrate dramatically changes the intensities of these two LSPR modes, by introducing constructive...... displaying a very large average SERS EF of >108. From a practical point of view, the developed SERS substrates are particularity interesting, since they are easy to handle and store and the fabrication is scalable, facilitating a wide and simple use of SERS in sensing applications....

  9. Horizontal silicon nanowires for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Gebavi, Hrvoje; Ristić, Davor; Baran, Nikola; Mikac, Lara; Mohaček-Grošev, Vlasta; Gotić, Marijan; Šikić, Mile; Ivanda, Mile

    2018-01-01

    The main purpose of this paper is to focus on details of the fabrication process of horizontally and vertically oriented silicon nanowires (SiNWs) substrates for the application of surface-enhanced Raman spectroscopy (SERS). The fabrication process is based on the vapor-liquid-solid method and electroless-assisted chemical etching, which, as the major benefit, resulting in the development of economical, easy-to-prepare SERS substrates. Furthermore, we examined the fabrication of Au coated Ag nanoparticles (NPs) on the SiNWs substrates in such a way as to diminish the influence of silver NPs corrosion, which, in turn, enhanced the SERS time stability, thus allowing for wider commercial applications. The substances on which high SERS sensitivity was proved are rhodamine (R6G) and 4-mercaptobenzoic acid (MBA), with the detection limits of 10-8 M and 10-6 M, respectively.

  10. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Zhou, Ji [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Tang, Bin, E-mail: bin.tang@deakin.edu.au [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Zeng, Tian; Li, Yaling [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Li, Jingliang [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Ye, Yong, E-mail: yeyong@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Wang, Xungai [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia)

    2016-11-15

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  11. Silicon nanohybrid-based surface-enhanced Raman scattering sensors.

    Science.gov (United States)

    Wang, Houyu; Jiang, Xiangxu; Lee, Shuit-Tong; He, Yao

    2014-11-01

    Nanomaterial-based surface-enhanced Raman scattering (SERS) sensors are highly promising analytical tools, capable of ultrasensitive, multiplex, and nondestructive detection of chemical and biological species. Extensive efforts have been made to design various silicon nanohybrid-based SERS substrates such as gold/silver nanoparticle (NP)-decorated silicon nanowires, Au/Ag NP-decorated silicon wafers (AuNP@Si), and so forth. In comparison to free AuNP- and AgNP-based SERS sensors, the silicon nanohybrid-based SERS sensors feature higher enhancement factors (EFs) and excellent reproducibility, since SERS hot spots are efficiently coupled and stabilized through interconnection to the semiconducting silicon substrates. Consequently, in the past decade, giant advancements in the development of silicon nanohybrid-based SERS sensors have been witnessed for myriad sensing applications. In this review, the representative achievements related to the design of high-performance silicon nanohybrid-based SERS sensors and their use for chemical and biological analysis are reviewed in a detailed way. Furthermore, the major opportunities and challenges in this field are discussed from a broad perspective and possible future directions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Assessing Telomere Length Using Surface Enhanced Raman Scattering

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Cui, Yiping

    2014-11-01

    Telomere length can provide valuable insight into telomeres and telomerase related diseases, including cancer. Here, we present a brand-new optical telomere length measurement protocol using surface enhanced Raman scattering (SERS). In this protocol, two single strand DNA are used as SERS probes. They are labeled with two different Raman molecules and can specifically hybridize with telomeres and centromere, respectively. First, genome DNA is extracted from cells. Then the telomere and centromere SERS probes are added into the genome DNA. After hybridization with genome DNA, excess SERS probes are removed by magnetic capturing nanoparticles. Finally, the genome DNA with SERS probes attached is dropped onto a SERS substrate and subjected to SERS measurement. Longer telomeres result in more attached telomere probes, thus a stronger SERS signal. Consequently, SERS signal can be used as an indicator of telomere length. Centromere is used as the inner control. By calibrating the SERS intensity of telomere probe with that of the centromere probe, SERS based telomere measurement is realized. This protocol does not require polymerase chain reaction (PCR) or electrophoresis procedures, which greatly simplifies the detection process. We anticipate that this easy-operation and cost-effective protocol is a fine alternative for the assessment of telomere length.

  13. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    International Nuclear Information System (INIS)

    Liu, Jun; Zhou, Ji; Tang, Bin; Zeng, Tian; Li, Yaling; Li, Jingliang; Ye, Yong; Wang, Xungai

    2016-01-01

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  14. Detection of explosive vapour using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Fang, X.; Ahmad, S. R.

    2009-11-01

    A commercially available nano-structured gold substrate was used for activating surface-enhanced Raman scattering (SERS). Raman spectra of the vapour of explosive material, triacetonetriperoxide (TATP), at trace concentrations produced from adsorbed molecules on such surfaces have been studied. Prominent Raman lines of the explosive molecular species were recorded at a sample temperature of ˜35°C, which is near to human body temperature. For this study, the concentration of the adsorbed TATP molecules on the nano-structured surface was varied by heating the sample to different temperatures and exposing the substrate to the sample vapour for different lengths of time. The intensities of the Raman lines have been found to increase with the increase in temperature and also with the increase in the duration of exposure for a fixed temperature. However, as expected, the Raman intensities have been found to saturate at higher temperatures and longer exposures. These saturation effects of the strengths of the Raman lines in the SERS of TATP vapour have been investigated in this paper. The results indicate that the optimisation for vapour deposition on the surface could be a crucial factor for any quantitative estimate of the concentration of the molecular species adsorbed on the nano-structured substrates.

  15. Rapid surface enhanced Raman scattering detection method for chloramphenicol residues

    Science.gov (United States)

    Ji, Wei; Yao, Weirong

    2015-06-01

    Chloramphenicol (CAP) is a widely used amide alcohol antibiotics, which has been banned from using in food producing animals in many countries. In this study, surface enhanced Raman scattering (SERS) coupled with gold colloidal nanoparticles was used for the rapid analysis of CAP. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 3-21G(d) and 6-31G(d) basis sets to analyze the assignment of vibrations. Affirmatively, the theoretical Raman spectrum of CAP was in complete agreement with the experimental spectrum. They both exhibited three strong peaks characteristic of CAP at 1104 cm-1, 1344 cm-1, 1596 cm-1, which were used for rapid qualitative analysis of CAP residues in food samples. The use of SERS as a method for the measurements of CAP was explored by comparing use of different solvents, gold colloidal nanoparticles concentration and absorption time. The method of the detection limit was determined as 0.1 μg/mL using optimum conditions. The Raman peak at 1344 cm-1 was used as the index for quantitative analysis of CAP in food samples, with a linear correlation of R2 = 0.9802. Quantitative analysis of CAP residues in foods revealed that the SERS technique with gold colloidal nanoparticles was sensitive and of a good stability and linear correlation, and suited for rapid analysis of CAP residue in a variety of food samples.

  16. Semi-quantitative analysis of indigo by surface enhanced resonance Raman spectroscopy (SERRS) using silver colloids

    Science.gov (United States)

    Shadi, I. T.; Chowdhry, B. Z.; Snowden, M. J.; Withnall, R.

    2003-08-01

    In this paper we report for the first time semi-quantitative analysis of indigo using surface enhanced Raman spectroscopy (SERS) and surface enhance resonance Raman spectroscopy (SERRS). Indigo, a dye widely used today in the textile industry, has been used, historically, both as a dye and as a pigment; the latter in both paintings and in printed material. The molecule is uncharged and largely insoluble in most solvents. The application of SERS/SERRS to the semi-quantitative analysis of indigo has been examined using aggregated citrate-reduced silver colloids with appropriate modifications to experimental protocols to both obtain and maximise SERRS signal intensities. Good linear correlations are observed for the dependence of the intensities of the SERRS band at 1151 cm -1 using laser exciting wavelengths of 514.5 nm ( R=0.9985) and 632.8 nm ( R=0.9963) on the indigo concentration over the range 10 -7-10 -5 and 10 -8-10 -5 mol dm -3, respectively. Band intensities were normalised against an internal standard (silver sol band at 243 cm -1). Resonance Raman spectra (RRS) of aqueous solutions of indigo could not be collected because of its low solubility and the presence of strong fluorescence. It was, however, possible to obtain RS and RRS spectra of the solid at each laser excitation wavelength. The limits of detection (L.O.D.) of indigo by SERS and SERRS using 514.5 and 632.8 nm were 9 ppm at both exciting wavelengths. Signal enhancement by SERS and SERRS was highly pH dependent due to the formation of singly protonated and possibly doubly protonated forms of the molecule at acidic pH. The SERS and SERRS data provide evidence to suggest that an excess of monolayer coverage of the dye at the surface of silver colloids is observed at concentrations greater than 7.85×10 -6 mol dm -3 for each exciting wavelength. The data reported herein also strongly suggest the presence of multiple species of the indigo molecule.

  17. [Terahertz-band study on surface enhanced Raman scattering of nanoparticle].

    Science.gov (United States)

    Wu, Yu-Deng; Ren, Guang-Jun; Hao, Yun; Yao, Jian-Quan

    2013-05-01

    Study on surface-enhanced Raman scattering in the terahertz-band proved in that the terahertz-band Raman enhancement also exists. By studing principles of electromagnetic enhancement of surface-enhanced Raman scattering, using the finite difference time-domain method, the electromagnetic enhancement of surface enhanced Raman scattering of nano-particles irradiated by terahertz-wave was simulated, and the enhancement effect of terahertz waves was analyzed. Simulation experiments show that using finite-difference time-domain method could obtain effectively accurate simulation result of nano-particle scattering, proving that for terahertz waves, surface-enhanced effects on the surface of the nano-particle also exist. The results for surface enhanced Raman scattering extended from the visible and infrared to terahertz-band, and provide a basis for application of the combination of surface-enhanced Raman scattering and terahertz-wave.

  18. Surface enhanced Raman spectroscopy on a flat graphene surface

    Science.gov (United States)

    Xu, Weigao; Ling, Xi; Xiao, Jiaqi; Dresselhaus, Mildred S.; Kong, Jing; Xu, Hongxing; Liu, Zhongfan; Zhang, Jin

    2012-01-01

    Surface enhanced Raman spectroscopy (SERS) is an attractive analytical technique, which enables single-molecule sensitive detection and provides its special chemical fingerprints. During the past decades, researchers have made great efforts towards an ideal SERS substrate, mainly including pioneering works on the preparation of uniform metal nanostructure arrays by various nanoassembly and nanotailoring methods, which give better uniformity and reproducibility. Recently, nanoparticles coated with an inert shell were used to make the enhanced Raman signals cleaner. By depositing SERS-active metal nanoislands on an atomically flat graphene layer, here we designed a new kind of SERS substrate referred to as a graphene-mediated SERS (G-SERS) substrate. In the graphene/metal combined structure, the electromagnetic “hot” spots (which is the origin of a huge SERS enhancement) created by the gapped metal nanoislands through the localized surface plasmon resonance effect are supposed to pass through the monolayer graphene, resulting in an atomically flat hot surface for Raman enhancement. Signals from a G-SERS substrate were also demonstrated to have interesting advantages over normal SERS, in terms of cleaner vibrational information free from various metal-molecule interactions and being more stable against photo-induced damage, but with a comparable enhancement factor. Furthermore, we demonstrate the use of a freestanding, transparent and flexible “G-SERS tape” (consisting of a polymer-layer-supported monolayer graphene with sandwiched metal nanoislands) to enable direct, real time and reliable detection of trace amounts of analytes in various systems, which imparts high efficiency and universality of analyses with G-SERS substrates. PMID:22623525

  19. DEPENDENCE OF THE SURFACE-ENHANCED RAMAN SCATTERING SIGNAL ON THE SHAPE OF SILVER NANOSTRUCTURES GROWN IN THE SiO2 /n-Si POROUS TEMPLATE

    Directory of Open Access Journals (Sweden)

    D. V. Yakimchuk

    2017-01-01

    Full Text Available Surface-enhanced Raman scattering is a powerful method used in chemoand biosensorics. The aim of this work was to determine the relationship between the signal of Surface-enhanced Raman scattering and the shape of silver nanostructures under the influence of laser radiation with different power.Plasmonic nanostructures were synthesized in silicon dioxide pores on monocrystalline silicon n-type substrate. The pores were formed using ion-track technology and selective chemical etching. Silver deposition was carried out by galvanic displacement method. Synthesis time was chosen as a parameter that allows controlling the shape of a silver deposit in the pores of silicon dioxide on the surface of single-crystal n-silicon during electrodeless deposition. Deposition time directly effects on the shape of metal nanostructures.Analysis of the dynamics of changing the morphology of the metal deposit showed that as the deposition time increases, the metal evolves from individual metallic crystallites within the pores at a short deposition time to dendritic-like nanostructures at a long time. The dependence of the intensity of Surface-enhanced Raman scattering spectra on the shape of the silver deposit is studied at the powers of a green laser (λ = 532 nm from 2.5 μW to 150 μW on the model dye analyte Rodamin 6G. The optimum shape of the silver deposit and laser power is analyzed from this point of view design of active surfaces for Surface-enhanced Raman scattering with nondestructive control of small concentrations of substances.The silver nanostructures obtained in porous template SiO2 on n-type silicon substrate could be used as plasmon-active surfaces for nondestructive investigations of substances with low concentrations at low laser powers. 

  20. Absorption/desorption in sprays

    International Nuclear Information System (INIS)

    Naimpally, A.

    1987-01-01

    This survey paper shall seek to present the present state of knowledge concerning absorption and desorption in spray chambers. The first part of the paper presents the theories and formulas for the atomization and break-up of sprays in nozzles. Formulas for the average (sauter-mean) diameters are then presented. For the case of absorption processes, the formulas for the dimensionless mass transfer coefficients is in drops. The total; mass transfer is the total of the transfer in individual drops. For the case of desorption of sparingly soluble gases from liquids in a spray chamber, the mass transfer occurs in the spray just at the point of break-up of the jet. Formulas for the desorption of gases are presented

  1. Validation of a Miniaturized Spectrometer for Trace Detection of Explosives by Surface-Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Salvatore Almaviva

    2016-08-01

    Full Text Available Surface-enhanced Raman spectroscopy (SERS measurements of some common military explosives were performed with a table-top micro-Raman system integrated with a Serstech R785 miniaturized device, comprising a spectrometer and detector for near-infrared (NIR laser excitation (785 nm. R785 was tested as the main component of a miniaturized SERS detector, designed for in situ and stand-alone sensing of molecules released at low concentrations, as could happen in the case of traces of explosives found in an illegal bomb factory, where solid microparticles of explosives could be released in the air and then collected on the sensor’s surface, if placed near the factory, as a consequence of bomb preparation. SERS spectra were obtained, exciting samples in picogram quantities on specific substrates, starting from standard commercial solutions. The main vibrational features of each substance were clearly identified also in low quantities. The amount of the sampled substance was determined through the analysis of scanning electron microscope images, while the spectral resolution and the detector sensitivity were sufficiently high to clearly distinguish spectra belonging to different samples with an exposure time of 10 s. A principal component analysis procedure was applied to the experimental data to understand which are the main factors affecting spectra variation across different samples. The score plots for the first three principal components show that the examined explosive materials can be clearly classified on the basis of their SERS spectra.

  2. Surface enhanced imaging and IR spectroscopy of the biological cells on the nanostructured gold film

    Directory of Open Access Journals (Sweden)

    G.I. Dovbeshko

    2017-07-01

    Full Text Available New approach for optical imaging, structural study and cell cultivation based on the effect of the enhancement of optical signals from biomolecules and biological cells near nanostructured rough gold surface is proposed. The surface enhanced IR absorption (SEIRA spectroscopy and confocal microscopy experiments were made using the culture of SPEV (porcine embryonic kidney epithelium transplantable line and fibroblast cells, cultivated and/or adsorbed on the gold substrate. The SEIRA spectra registered from monolayer of the SPEV cells cultivated on the rough gold showed a low frequency shift of about 2 to 7 cm 1 for the most characteristic IR vibrations, compared with those adsorbed from suspension on the same substrate. An enhancement factor of 15…30 was obtained for different molecular vibrations. The confocal microscopy contrast images of the SPEV cells on rough gold substrate were obtained in laser fluorescence mode. This approach opens new possibilities for visualization of the living cells in vivo without staining. The fluorescence of the rough gold surfaces and effects responsible for our findings have been discussed.

  3. Surface-enhanced Raman scattering active gold nanoparticle/nanohole arrays fabricated through electron beam lithography

    Science.gov (United States)

    Wu, Tsunghsueh; Lin, Yang-Wei

    2018-03-01

    Effective surface-enhanced Raman scattering (SERS)-active substrates from gold nanoparticle and gold nanohole arrays were successfully fabricated through electron beam lithography with precise computer-aided control of the unit size and intergap distance. Their SERS performance was evaluated using 4-mercaptobenzoic acid (4-MBA). These gold arrays yielded strong SERS signals under 785 nm laser excitation. The enhancement factors for 4-MBA molecules on the prepared gold nanoparticle and nanohole arrays maxed at 1.08 × 107 and 8.61 × 106, respectively. The observed increase in SERS enhancement was attributed to the localized surface plasmon resonance (LSPR) wavelength shifting toward the near-infrared regime when the gold nanohole diameter increased, in agreement with the theoretical prediction in this study. The contribution of LSPR to the Raman enhancement from nanohole arrays deposited on fluorine-doped tin oxide glass was elucidated by comparing SERS and transmission spectra. This simple fabrication procedure, which entails employing electron beam lithography and the controllability of the intergap distance, suggests highly promising uses of nanohole arrays as functional components in sensing and photonic devices.

  4. Electromagnetic theories of surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin

    2017-07-07

    Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

  5. In situ surface-enhanced raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface

    NARCIS (Netherlands)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan William; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin

    2015-01-01

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (<100 mu L) with a compact three-electrode configuration for in situ surface-enhanced Raman spectroelectrochemistry. The SEC

  6. In situ surface-enhanced Raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface

    NARCIS (Netherlands)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin T

    2015-01-01

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (<100 μL) with a compact three-electrode configuration for in situ surface-enhanced Raman spectroelectrochemistry. The SEC system

  7. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

    2010-01-01

    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  8. Lasers

    OpenAIRE

    Passeron, Thierry

    2012-01-01

    International audience; Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be succesfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-aulait macules should not b...

  9. Laser

    OpenAIRE

    Du, K.; Loosen, P.; Herziger, G.

    1991-01-01

    Laser, consisting of a beam path multiple-folded by means of two cavity end mirrors and having at least one reflector folding the laser beam retroreflectively, the axis of which is arranged offset in parallel to the axis of a further reflector. So that the laser exhibits an improved beam quality while retaining its comparatively low adjustment sensitivity, the beam path is folded at least twice by means of the retoreflective reflector.

  10. SPS Ion Induced Desorption Experiment

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    This experiment will give a study about the induced desorption from heavy ion (Indium ion run from week 45 in SPS T4-H8 area) impacting LHC type graphite collimator. 4 different samples are located in the 4 chambers 90° one to each other: pure graphite, graphite with copper coating, graphite with NEG coating, 316LN stainless steal (reference).

  11. Development of Advanced Surface Enhancement Technology for Decreasing Wear and Corrosion of Equipment Used for Mineral Processing

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Tao; R. Honaker; B. K. Parekh

    2007-09-20

    Equipment wear is a major concern in the mineral processing industry, which dramatically increases the maintenance cost and adversely affects plant operation efficiency. In this research, novel surface treatment technologies, High Density Infrared (HDI) and Laser Surface Engineering (LSE) surface coating processes were developed for the surface enhancement of selected mineral and coal processing equipment. Microstructural and mechanical properties of the coated specimens were characterized. Laboratory-simulated wear tests were conducted to evaluate the tribological performance of the coated components. Test results indicate that the wear resistance of ASTM A36 (raw coal screen section) and can be significantly increased by applying HDI and LSE coating processes. Field testing has been performed using a LSE-treated screen panel and it showed a significant improvement of the service life.

  12. Development of Advanced Surface Enhancement Technology for Decreasing Wear and Corrosion of Equipment Used for Mineral Processing

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Tao; Craig A. Blue

    2006-07-20

    Equipment wear is a major concern in the mineral processing industry, which dramatically increases the maintenance cost and adversely affects plant operation efficiency. In this research, novel surface treatment technologies, High Density Infrared (HDI) and Laser Surface Engineering (LSE) surface coating processes were developed for the surface enhancement of selected mineral processing equipment. Microstructural and mechanical properties of the coated specimens were characterized. Laboratory-simulated wear tests were conducted to evaluate the tribological performance of the coated components. Test results indicate that the wear resistance of ASTM A36 (raw coal screen section) and can be significantly increased by applying HDI and LSE coating processes. Field testing has been performed using a LSE-treated screen panel and it showed a 2 times improvement of the service life.

  13. Lasers.

    Science.gov (United States)

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  14. [Lasers].

    Science.gov (United States)

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  15. Desorption of pyrethroids from suspended solids.

    Science.gov (United States)

    Fojut, Tessa L; Young, Thomas M

    2011-08-01

    Pyrethroid insecticides have been widely detected in sediments at concentrations that can cause toxicity to aquatic organisms. Desorption rates play an important role in determining the bioavailability of hydrophobic organic compounds, such as pyrethroids, because these compounds are more likely to be sorbed to solids in the environment, and times to reach sorptive equilibrium can be long. In the present study, sequential Tenax desorption experiments were performed with three sorbents, three aging times, and four pyrethroids. A biphasic rate model was fit to the desorption data with r(2)  > 0.99, and the rapid and slow compartment desorption rate constants and compartment fractions are reported. Suspended solids from irrigation runoff water collected from a field that had been sprayed with permethrin 1 d before were used in the experiments to compare desorption rates for field-applied pyrethroids with those for laboratory-spiked materials. Suspended solids were used in desorption experiments because suspended solids can be a key source of hydrophobic compounds in surface waters. The rapid desorption rate parameters of field-applied permethrin were not statistically different from those of laboratory spiked permethrin, indicating that desorption of the spiked pyrethroids is comparable to desorption of the pyrethroids added and aged in the field. Sorbent characteristics had the greatest effect on desorption rate parameters; as organic carbon content of the solids increased, the rapid desorption fractions and rapid desorption rate constants both decreased. The desorption rate constant of the slow compartment for sediment containing permethrin aged for 28 d was significantly different compared to aging for 1 d and 7 d, whereas desorption in the rapid and slow compartments did not differ between these treatments. Copyright © 2011 SETAC.

  16. Thermal desorption spectroscopy of palladium and copper on silica

    Science.gov (United States)

    Pierce, Daniel E.; Burns, Richard P.; Gabriel, Kenneth A.

    Thermal desorption spectroscopy of palladium and copper films grown on clean silica substrates was performed using CO2 laser heating. After cleaning the surface by high temperature heating, a controlled, low coverage dose of metal atoms was deposited on the substrate. Temperature ramping was achieved using a constant laser power, the value of which depended on the nature of the metal and substrate as well as the substrate size. At high temperatures (above 1025 K for palladium and above 975 K for copper), metal films vaporize and desorption spectra provide information about the nature of the metal deposit and metal-support interaction. With increasing coverage of palladium on silica, a positive temperature shift in the leading edge of desorption was seen. At higher coverages, above about 2 x 10(exp 15) atoms/sq cm, a common leading edge appears and zero-order kinetic analysis gave E(sub act) values between 3.9 and 4.3 +/- 0.1 eV which can be compared with the value of 3.83 eV for Delta (H(sub vap)) (1200 K) for palladium metal. Similar coverage-dependent properties were not seen for copper on silica; instead, a common desorption leading edge appeared down to submonolayer coverages. Zero-order analysis at about 1 x 10(exp 15) atoms/sq cm gave an E(sub act) of 3.3 +/- 0.1 eV, which is comparable with the value of 3.44 eV for Delta (H(sub vap)) (1100 K) for copper metal.

  17. Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

    Science.gov (United States)

    Pavel, Ioana E.; Alnajjar, Khadijeh S.; Monahan, Jennifer L.; Stahler, Adam; Hunter, Nora E.; Weaver, Kent M.; Baker, Joshua D.; Meyerhoefer, Allie J.; Dolson, David A.

    2012-01-01

    A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by…

  18. Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds

    NARCIS (Netherlands)

    Arraez Roman, D.; Efremov, E.V.; Ariese, F.; Segura Carretero, A.; Gooijer, C.

    2005-01-01

    The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram

  19. Surface enhanced second harmonic generation from macrocycle, catenane, and rotaxane thin films : Experiments and theory

    NARCIS (Netherlands)

    Arfaoui, I.; Bermudez, V.; Bottari, G.; De Nadai, C.; Jalkanen, J.P.; Kajzar, F.; Leigh, D.A.; Lubomska, M.; Mendoza, S.M.; Niziol, J.; Rudolf, Petra; Zerbetto, F.

    2006-01-01

    Surface enhanced second harmonic generation (SE SHG) experiments on molecular structures, macrocycles, catenanes, and rotaxanes, deposited as monolayers and multilayers by vacuum sublimation on silver, are reported. The measurements show that the molecules form ordered thin films, where the highest

  20. Surface enhanced SHG from macrocycle, catenane and rotaxane thin films : experiments and theory.

    NARCIS (Netherlands)

    Arfaoui, I.; Bermudez, V.; De Nadai, C.; Jalkanen, J.-P.; Kajzar, F.; Leigh, D.A.; Lubomska, M.; Mendoza, S.M.; Niziol, J.; Rudolf, Petra; Zerbetto, F.; Grote, JG; Kaino, T; Kajzar, F

    2005-01-01

    Surface enhanced second harmonic generation experiments on supramolecules: macrocycles, catenanes and rotaxanes, monolayers and multilayers deposited by vacuum evaporation on silver layers are reported and described. The measurements show that the molecules are ordered in thin films. The highest

  1. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  2. Microfluidic setup for on-line SERS monitoring using laser induced nanoparticle spots as SERS active substrate

    Directory of Open Access Journals (Sweden)

    Oana-M. Buja

    2017-01-01

    Full Text Available A microfluidic setup which enables on-line monitoring of residues of malachite green (MG using surface-enhanced Raman scattering (SERS is reported. The SERS active substrate was prepared via laser induced synthesis of silver or gold nanoparticles spot on the bottom of a 200 μm inner dimension glass capillary, by focusing the laser beam during a continuous flow of a mixture of silver nitrate or gold chloride and sodium citrate. The described microfluidic setup enables within a few minutes the monitoring of several processes: the synthesis of the SERS active spot, MG adsorption to the metal surface, detection of the analyte when saturation of the SERS signal is reached, and finally, the desorption of MG from the spot. Moreover, after MG complete desorption, the regeneration of the SERS active spot was achieved. The detection of MG was possible down to 10−7 M concentration with a good reproducibility when using silver or gold spots as SERS substrate.

  3. Pulsed laser deposition of bimetallic gold–platinum nanoparticles on cerium oxide and their characterisation by X-ray photoelectron spectroscopy and temperature-programmed desorption of isotopically labelled carbon monoxide

    Czech Academy of Sciences Publication Activity Database

    Plšek, Jan; Bastl, Zdeněk

    2013-01-01

    Roč. 109, MAR 2013 (2013), s. 109-118 ISSN 0021-9517 R&D Projects: GA ČR GA104/08/1501 Institutional support: RVO:61388955 Keywords : pulsed laser deposition * cerium oxide * Au-Pt nanostructures Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.073, year: 2013

  4. Semi-quantitative analysis of indigo carmine, using silver colloids, by surface enhanced resonance Raman spectroscopy (SERRS)

    Science.gov (United States)

    Shadi, I. T.; Chowdhry, B. Z.; Snowden, M. J.; Withnall, R.

    2003-08-01

    The application of surface enhanced resonance Raman spectroscopy (SERRS) to the semi-quantitative analysis of the dye, indigo carmine, has been examined using citrate-reduced silver colloids. Good linear correlations are observed for the dye band at 1580 cm -1 in the concentration range 10 -7-10 -5 and 10 -9-10 -5 mol dm -3, using laser exciting wavelengths of 514.5 [( R=0.9983)] and 632.8 nm [( R=0.9978)], respectively. At concentrations of dye above 10 -6 M the concentration dependence of the SERRS signals is non-linear due to the coverage of the surface of the colloidal particles by the dye being in excess of a full monolayer. At concentrations above 10 -6 M resonance Raman spectroscopy (RRS) can be employed for the quantitative analysis of the dye. An internal standard was used and a good linear correlation ( R=0.997) was observed for the dependence of dye signal intensities at 1580 cm -1 in the concentration range 10 -5-10 -4 M using a laser exciting wavelength of 514.5 nm. The limits of detection of indigo carmine by SERRS (514.5 nm), SERRS (632.8 nm) and solution RRS (514.5 nm) are found to be 0.9, 1 and 38 ppm, respectively.

  5. Surface enhanced Raman optical activity as an ultra sensitive tool for ligand binding analysis

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim

    2007-01-01

    The Surface Enhanced Resonance Raman Scattering (SERRS) and Surface Enhanced Resonance Raman Optical Activity (SERROA) spectra of myoglobin and the myoglobin-azide complex were measured on very dilute samples (100 nM protein) in order to analyze the sensitivity of SERROA spectroscopy when inducing...... upon azide complexation. Application of this method allows for rapid analysis of ligand binding in metalloproteins in dilute aqueous solution and could in the future, when combined with theoretical studies, increase the obtainable structural resolution of proteins beyond that of X-ray analysis....

  6. Surface-enhanced Raman imaging of fractal shaped periodic metal nanostructures

    DEFF Research Database (Denmark)

    Beermann, Jonas; Novikov, Sergey Mikhailovich; Albrektsen, Ole

    2009-01-01

    Surface-enhanced Raman scattering (SERS) from Rhodamine 6G (R6G) homogenously adsorbed on fractal shaped 170-nm-period square arrays formed by 50-nm-high gold nanoparticles (diameters of 80, 100, or 120 nm are constant within each array), fabricated on a smooth gold film by electron-be