Multisample matrix-assisted laser desorption source for molecular beams of neutral peptides

International Nuclear Information System (INIS)

Lupulescu, C.; Abd El Rahim, M.; Antoine, R.; Barbaire, M.; Broyer, M.; Dagany, X.; Maurelli, J.; Rayane, D.; Dugourd, Ph.

2006-01-01

We developed and tested a multisample laser desorption source for producing stable molecular beams of neutral peptides. Our apparatus is based on matrix-assisted laser desorption technique. The source consists of 96 different targets which may be scanned by a software control procedure. Examples of molecular beams of neutral peptides are presented, as well as the influence of the different source parameters on the jet

Processing of C60 thin films by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

DEFF Research Database (Denmark)

Canulescu, Stela; Schou, Jørgen; Fæster, Søren

2011-01-01

Thin films of fullerenes (C60) were deposited onto silicon using matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out from a frozen homogeneous dilute solution of C60 in anisole (0.67 wt%), and over a broad range of laser fluences, from 0.15 J/cm2 up to 3.9 J/cm2. MAPLE...

Surface morphology of thin lysozyme films produced by matrix-assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Purice, Andreea; Schou, Jørgen; Pryds, Nini

2007-01-01

Thin films of the protein, lysozyme, have been deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. Frozen targets of 0.3-1.0 wt.% lysozyme dissolved in ultrapure water were irradiated by laser light at 355 mn with a fluence of 2 J/cm(2). The surface quality of the thin....... The concentration of lysozyme in the ice matrix apparently does not play any significant role for the morphology of the film. The morphology obtained with MAPLE has been compared with results for direct laser irradiation of a pressed lysozyme sample (i.e. pulsed laser deposition (PLD)). (C) 2007 Elsevier B.V. All...

Study of ionization process of matrix molecules in matrix-assisted laser desorption ionization

Energy Technology Data Exchange (ETDEWEB)

Murakami, Kazumasa; Sato, Asami; Hashimoto, Kenro; Fujino, Tatsuya, E-mail: fujino@tmu.ac.jp

2013-06-20

Highlights: ► Proton transfer and adduction reaction of matrix in MALDI were studied. ► Hydroxyl group forming intramolecular hydrogen bond was related to the ionization. ► Intramolecular proton transfer in the electronic excited state was the initial step. ► Non-volatile analytes stabilized protonated matrix in the ground state. ► A possible mechanism, “analyte support mechanism”, has been proposed. - Abstract: Proton transfer and adduction reaction of matrix molecules in matrix-assisted laser desorption ionization were studied. By using 2,4,6-trihydroxyacetophenone (THAP), 2,5-dihydroxybenzoic acid (DHBA), and their related compounds in which the position of a hydroxyl group is different, it was clarified that a hydroxyl group forming an intramolecular hydrogen bond is related to the ionization of matrix molecules. Intramolecular proton transfer in the electronic excited state of the matrix and subsequent proton adduction from a surrounding solvent to the charge-separated matrix are the initial steps for the ionization of matrix molecules. Nanosecond pump–probe NIR–UV mass spectrometry confirmed that the existence of analyte molecules having large dipole moment in their structures is necessary for the stabilization of [matrix + H]{sup +} in the electronic ground state.

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

Deposition of matrix-free fullerene films with improved morphology by matrix-assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Canulescu, Stela; Schou, Jørgen; Fæster, Søren

2013-01-01

Thin films of C60 were deposited by matrix-assisted pulsed laser evaporation (MAPLE) from a frozen target of anisole with 0.67 wt% C60. Above a fluence of 1.5 J/cm2 the C60 films are strongly non-uniform and are resulting from transfer of matrix-droplets containing fullerenes. At low fluence...... the fullerene molecules in the films are intact, the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the film. This may indicate a regime of dominant evaporation at low fluence which merges into the MAPLE regime of liquid ejection of the host matrix...

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

Science.gov (United States)

Wang, Ren-Qi; Bao, Kai; Croué, Jean-Philippe; Ng, Siu Choon

2013-11-21

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.

Characterisation of bacteria by matrix-assisted laser desorption/ionisation and electrospray mass spectrometry

NARCIS (Netherlands)

Baar, B.L.M. van

2000-01-01

Chemical analysis for the characterisation of micro-organisms is rapidly evolving, after the recent advent of new ionisation methods in mass spectrometry (MS): electrospray (ES) and matrix-assisted laser desorption/ionisation (MALDI). These methods allow quick characterisation of micro-organisms,

Mesoporous tungsten titanate as matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of biomolecules

International Nuclear Information System (INIS)

Shan Zhe; Han Lu; Yuan Minjia; Deng Chunhui; Zhao Dongyuan; Tu Bo; Yang Pengyuan

2007-01-01

In this paper, mesoporous tungsten titanate (WTiO) with different nano-pore structures was utilized as matrix for the analysis of short peptides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Effect of characteristic features of mesoporous matrices on laser desorption/ionization process was investigated. Experiments showed that the ordered two-dimensional and three-dimensional mesoporous matrices were superior in performance to the non-ordered WTiO matrix. The dramatic enhancement of signal sensitivity by the ordered mesoporous matrices can be reasonably attributed to the ordered structure, which facilitated the understanding on structure-function relationship in mesoporous cavity for laser desorption process of adsorbed biomolecules. With the ordered mesoporous matrix, the short peptides are successfully detected. The presence of trace alkali metal salt effectively increased the analyte ion yields and the MALDI-TOFMS using the inorganic mesoporous matrices displayed a high salt tolerance. The developed technique also showed a satisfactory performance in peptide-mapping and amino-acid sequencing analysis

Matrix-assisted laser-desorption-ionization mass spectrometry of proteins using a free-electron laser

International Nuclear Information System (INIS)

Cramer, R.; Hillenkamp, F.; Haglund, R.

1995-01-01

Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) is one of the most promising techniques for spectral fingerprinting large molecules, such as proteins, oligonucleotides and carbohydrates. In the usual implementation of this technique, the analyte molecule is dissolved in an aromatic liquid matrix material which resonantly absorbs ultraviolet laser light. Resonant absorption by π-π* transitions volatilizes the matrix and initiates subsequent charge transfer to the analyte molecules, which are detected by time-of-flight mass spectrometry. Recent MALDI-MS studies with Er:YAG (2.94 μm) and CO 2 4 (9.4-10.6 μm) lasers suggest that them is significant unexplored potential for mass spectrometry of macromolecules, including oligonucleotide, in the mid-infrared. Preliminary experiments show that it is possible to capitalize on the rich rovibronic absorption spectrum of virtually all organics to initiate resonant desorption in matrix material over the entire range of pH values. However, the mechanism of charge transfer is particularly problematic for infrared MALDI because of the low photon energy. In this paper, we report the results of MALI-MS studies on small proteins using the Vanderbilt FEL and several matrix materials. Proteins with masses up to roughly 6,000 amu were detected with high resolution in a linear time-of-flight mass spectrometer. By varying the pulse duration using a broadband Pockels cell, we have been able to compare the results of relatively long (5 μs) and short (0.1 μs) irradiation on the desorption and ionization processes. Compared to uv-MALDI spectra of identical analytes obtained with a nitrogen laser (337 nm) in the same time-of-flight spectrometer, the infrared results appear to show that the desorption and ionization process goes on over a somewhat longer time scale

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...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Purice, Andreea; Schou, Jørgen; Kingshott, P.

2007-01-01

Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal 2...... microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm(2) and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI......-TOF-MS) analysis demonstrate that the chemistry, molecular weight and polydispersity of the PEG films were identical to the starting material. Studies of the film surface with scanning electron microscopy (SEM) indicate that the Si-substrate is covered by a relatively homogenous PEG film with few bare spots. (c...

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.

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...

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.

Is energy pooling necessary in ultraviolet matrix-assisted laser desorption/ionization?

Science.gov (United States)

Lin, Hou-Yu; Song, Botao; Lu, I-Chung; Hsu, Kuo-Tung; Liao, Chih-Yu; Lee, Yin-Yu; Tseng, Chien-Ming; Lee, Yuan-Tseh; Ni, Chi-Kung

2014-01-15

Energy pooling has been suggested as the key process for generating the primary ions during ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI). In previous studies, decreases in fluorescence quantum yields as laser fluence increased for 2-aminobenzoic acid, 2,5-dihydroxybenzoic acid (2,5-DHB), and 3-hydroxypicolinic acid were used as evidence of energy pooling. This work extends the research to other matrices and addresses whether energy pooling is a universal property in UV-MALDI. Energy pooling was investigated in a time-resolved fluorescence experiment by using a short laser pulse (355 nm, 20 ps pulse width) for excitation and a streak camera (1 ps time resolution) for fluorescence detection. The excited-state lifetime of 2,5-DHB decreased with increases in laser fluence. This suggests that a reaction occurs between two excited molecules, and that energy pooling may be one of the possible reactions. However, the excited-state lifetime of 2,4,6-trihydroxyacetophenone (THAP) did not change with increases in laser fluence. The upper limit of the energy pooling rate constant for THAP is estimated to be approximately 100-500 times smaller than that of 2,5-DHB. The small energy pooling rate constant for THAP indicates that the potential contribution of the energy pooling mechanism to the generation of THAP matrix primary ions should be reconsidered. Copyright © 2013 John Wiley & Sons, Ltd.

Layered double hydroxides/polymer thin films grown by matrix assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Birjega, R.; Matei, A.; Mitu, B.; Ionita, M.D.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest–Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Corobea, M.C. [National R. and S. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021, Bucharest (Romania)

2013-09-30

Due to their highly tunable properties, layered double hydroxides (LDHs) are an emerging class of the favorably layered crystals used for the preparation of multifunctional polymer/layered crystal nanocomposites. In contrast to cationic clay materials with negatively charge layers, LDHs are the only host lattices with positively charged layers (brucite-like), with interlayer exchangeable anions and intercalated water. In this work, the deposition of thin films of Mg and Al based LDH/polymers nanocomposites by laser techniques is reported. Matrix assisted pulsed laser evaporation was the method used for thin films deposition. The Mg–Al LDHs capability to act as a host for polymers and to produce hybrid LDH/polymer films has been investigated. Polyethylene glycol with different molecular mass compositions and ethylene glycol were used as polymers. The structure and surface morphology of the deposited LDH/polymers films were examined by X-ray diffraction, Fourier transform infra-red spectroscopy, atomic force microscopy and scanning electron microscopy. - Highlights: • Hybrid composites deposited by matrix assisted pulsed laser evaporation (MAPLE). • Mg–Al layered double hydroxides (LDH) and polyethylene glycol (PEG) are used. • Mixtures of PEG1450 and LDH were deposited by MAPLE. • Deposited thin films preserve the properties of the starting material. • The film wettability can be controlled by the amount of PEG.

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

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 for...... inhibitor, were quantified by MALDI-time-of-flight (TOF) mass spectrometry.......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...

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.

UV and RIR matrix assisted pulsed laser deposition of organic MEH-PPV films

International Nuclear Information System (INIS)

Toftmann, B.; Papantonakis, M.R.; Auyeung, R.C.Y.; Kim, W.; O'Malley, S.M.; Bubb, D.M.; Horwitz, J.S.; Schou, J.; Johansen, P.M.; Haglund, R.F.

2004-01-01

A comparative study of thin film production based on gentle laser-ablation techniques has been carried out with the luminescent polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene]. Using a free-electron laser films were made by resonant infrared pulsed laser deposition (RIR-PLD). For the first time resonant infrared matrix assisted pulsed laser evaporation (RIR-MAPLE) was successfully demonstrated on a luminescent polymer system. In addition to this, an excimer laser has been used for UV-MAPLE depositions at 193 and 248-nm irradiation. Films deposited onto NaCl and quartz substrates were analyzed by Fourier transform infrared spectroscopy, UV-visible absorbance and photoluminescence. Photoluminescent material was deposited by RIR-MAPLE and 248-nm MAPLE, while the RIR-PLD and 193-nm-MAPLE depositions displayed the smoothest surfaces but did not show photoluminescence

UV and RIR matrix assisted pulsed laser deposition of organic MEH-PPV films

DEFF Research Database (Denmark)

Christensen, Bo Toftmann; Papantonalis, M.R.; Auyeung, R.C.Y.

2004-01-01

-PLD). For the first time resonant infrared matrix assisted pulsed laser evaporation (RIR-MAPLE) was successfully demonstrated on a luminescent polymer system. In addition to this, an excimer laser has been used for UV-MAPLE depositions at 193 and 248-nm irradiation. Films deposited onto NaCl and quartz substrates......A comparative study of thin film production based on gentle laser-ablation techniques has been carried out with the luminescent polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene]. Using a free-electron laser films were made by resonant infrared pulsed laser deposition (RIR...... were analyzed by Fourier transform infrared spectroscopy, UV-visible absorbance and photoluminescence. Photoluminescent material was deposited by RIR-MAPLE and 248-nm MAPLE, while the RIR-PLD and 193-nm-MAPLE depositions displayed the smoothest surfaces but did not show photoluminescence. (C) 2003...

Dansyl-peptides matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) and tandem mass spectrometric (MS/MS) features improve the liquid chromatography/MALDI-MS/MS analysis of the proteome.

Science.gov (United States)

Chiappetta, Giovanni; Ndiaye, Sega; Demey, Emmanuelle; Haddad, Iman; Marino, Gennaro; Amoresano, Angela; Vinh, Joëlle

2010-10-30

Peptide tagging is a useful tool to improve matrix-assisted laser desorption/ionization tandem mass spectrometric (MALDI-MS/MS) analysis. We present a new application of the use of the dansyl chloride (DNS-Cl). DNS-Cl is a specific primary amine reagent widely used in protein biochemistry. It adds a fluorescent dimethylaminonaphthalene moiety to the molecule. The evaluation of MALDI-MS and MS/MS analyses of dansylated peptides shows that dansylation raises the ionization efficiency of the most hydrophilic species compared with the most hydrophobic ones. Consequently, higher Mascot scores and protein sequence coverage are obtained by combining MS and MS/MS data of native and tagged samples. The N-terminal DNS-Cl sulfonation improves the peptide fragmentation and promotes the generation of b-fragments allowing better peptide sequencing. In addition, we set up a labeling protocol based on the microwave chemistry. Peptide dansylation proved to be a rapid and cheap method to improve the performance of liquid chromatography (LC)/MALDI-MS/MS analysis at the proteomic scale in terms of peptide detection and sequence coverage. Copyright © 2010 John Wiley & Sons, Ltd.

Laser desorption ionization mass spectrometry: Recent progress in matrix-free and label-assisted techniques.

Science.gov (United States)

Mandal, Arundhoti; Singha, Monisha; Addy, Partha Sarathi; Basak, Amit

2017-10-13

The MALDI-based mass spectrometry, over the last three decades, has become an important analytical tool. It is a gentle ionization technique, usually applicable to detect and characterize analytes with high molecular weights like proteins and other macromolecules. The earlier difficulty of detection of analytes with low molecular weights like small organic molecules and metal ion complexes with this technique arose due to the cluster of peaks in the low molecular weight region generated from the matrix. To detect such molecules and metal ion complexes, a four-prong strategy has been developed. These include use of alternate matrix materials, employment of new surface materials that require no matrix, use of metabolites that directly absorb the laser light, and the laser-absorbing label-assisted LDI-MS (popularly known as LALDI-MS). This review will highlight the developments with all these strategies with a special emphasis on LALDI-MS. © 2017 Wiley Periodicals, Inc.

Iron oxide nanomatrix facilitating metal ionization in matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Obena, Rofeamor P; Lin, Po-Chiao; Lu, Ying-Wei; Li, I-Che; del Mundo, Florian; Arco, Susan dR; Nuesca, Guillermo M; Lin, Chung-Chen; Chen, Yu-Ju

2011-12-15

The significance and epidemiological effects of metals to life necessitate the development of direct, efficient, and rapid method of analysis. Taking advantage of its simple, fast, and high-throughput features, we present a novel approach to metal ion detection by matrix-functionalized magnetic nanoparticle (matrix@MNP)-assisted MALDI-MS. Utilizing 21 biologically and environmentally relevant metal ion solutions, the performance of core and matrix@MNP against conventional matrixes in MALDI-MS and laser desorption ionization (LDI) MS were systemically tested to evaluate the versatility of matrix@MNP as ionization element. The matrix@MNPs provided 20- to >100-fold enhancement on detection sensitivity of metal ions and unambiguous identification through characteristic isotope patterns and accurate mass (<5 ppm), which may be attributed to its multifunctional role as metal chelator, preconcentrator, absorber, and reservoir of energy. Together with the comparison on the ionization behaviors of various metals having different ionization potentials (IP), we formulated a metal ionization mechanism model, alluding to the role of exciton pooling in matrix@MNP-assisted MALDI-MS. Moreover, the detection of Cu in spiked tap water demonstrated the practicability of this new approach as an efficient and direct alternative tool for fast, sensitive, and accurate determination of trace metal ions in real samples.

Focused Electrospray Deposition for Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

International Nuclear Information System (INIS)

Jeong, Kyung Hwan; Seo, Jong Cheol; Yoon, Hye Joo; Shin, Seung Koo

2010-01-01

Focused electrospray (FES) deposition method is presented for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. FES ion optics consists of two cylindrical focusing electrodes capped with a truncated conical electrode through which an electrospray emitter passes along the cylindrical axis. A spray of charged droplets is focused onto a sample well on a MALDI target plate under atmospheric pressure. The shape and size distributions of matrix crystals are visualized by scanning electron microscope and the mass spectra are obtained by time-of-flight mass spectrometry. Angiotensin II, bradykinin, and substance P are used as test samples, while α-cyano-4-hydroxycinnamic acid and dihydroxybenzoic acid are employed as matrices. FES of a sample/matrix mixture produces fine crystal grains on a 1.3 mm spot and reproducibly yields the mass spectra with little shot-to-shot and spot-to-spot variations. Although FES greatly stabilizes the signals, the space charge due to matrix ions limits the detection sensitivity of peptides. To avoid the space charge problem, we adopted a dual FES/FES mode, which separately deposits matrix and sample by FES in sequence. The dual FES/FES mode reaches the detection sensitivity of 0.88 amol, enabling ultrasensitive detection of peptides by homogeneously depositing matrix and sample under atmospheric pressure

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.

[Special application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry in clinical microbiological diagnostics].

Science.gov (United States)

Nagy, Erzsébet; Abrók, Marianna; Bartha, Noémi; Bereczki, László; Juhász, Emese; Kardos, Gábor; Kristóf, Katalin; Miszti, Cecilia; Urbán, Edit

2014-09-21

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry as a new possibility for rapid identification of bacteria and fungi revolutionized the clinical microbiological diagnostics. It has an extreme importance in the routine microbiological laboratories, as identification of the pathogenic species rapidly will influence antibiotic selection before the final determination of antibiotic resistance of the isolate. The classical methods for identification of bacteria or fungi, based on biochemical tests, are influenced by many environmental factors. The matrix-assisted laser desorption ionization time-of-flight mass spectrometry is a rapid method which is able to identify a great variety of the isolated bacteria and fungi based on the composition of conserved ribosomal proteins. Recently several other applications of the method have also been investigated such as direct identification of pathogens from the positive blood cultures. There are possibilities to identify bacteria from the urine samples in urinary tract infection or from other sterile body fluids. Using selective enrichment broth Salmonella sp from the stool samples can be identified more rapidly, too. The extended spectrum beta-lactamase or carbapenemase production of the isolated bacteria can be also detected by this method helping the antibiotic selection in some cases. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry based methods are suitable to investigate changes in deoxyribonucleic acid or ribonucleic acid, to carry out rapid antibiotic resistance determination or other proteomic analysis. The aim of this paper is to give an overview about present possibilities of using this technique in the clinical microbiological routine procedures.

Hydroxyapatite thin films grown by pulsed laser deposition and matrix assisted pulsed laser evaporation: Comparative study

Science.gov (United States)

Popescu-Pelin, G.; Sima, F.; Sima, L. E.; Mihailescu, C. N.; Luculescu, C.; Iordache, I.; Socol, M.; Socol, G.; Mihailescu, I. N.

2017-10-01

Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) techniques were applied for growing hydroxyapatite (HA) thin films on titanium substrates. All experiments were conducted in a reaction chamber using a KrF* excimer laser source (λ = 248 nm, τFWHM ≈ 25 ns). Half of the samples were post-deposition thermally treated at 500 °C in a flux of water vapours in order to restore crystallinity and improve adherence. Coating surface morphologies and topographies specific to the deposition method were evidenced by scanning electron, atomic force microscopy investigations and profilometry. They were shown to depend on deposition technique and also on the post-deposition treatment. Crystalline structure of the coatings evaluated by X-ray diffraction was improved after thermal treatment. Biocompatibility of coatings, cellular adhesion, proliferation and differentiation tests were conducted using human mesenchymal stem cells (MSCs). Results showed that annealed MAPLE deposited HA coatings were supporting MSCs proliferation, while annealed PLD obtained films were stimulating osteogenic differentiation.

Characterization of polyesters by matrix-assisted laser desorption/ionization and Fourier transform mass spectrometry.

Science.gov (United States)

Mize, Todd H; Simonsick, William J; Amster, I Jonathan

2003-01-01

Two homopolyesters, poly(neopentyl glycol-alt-isophthalic acid) and poly(hexanediol-alt-azelaic acid), and two copolyesters, poly(dipropoxylated bisphenol-A-alt-(isophthalic acid-co-adipic acid)) and poly(neopentyl glycol-alt-(adipic acid-co-isophthalic acid)) were analyzed by internal source matrix assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS). The high resolution and high mass accuracy provided by FTMS greatly facilitate the characterization of the polyester and copolyester samples. Isobaric resolution allows the ion abundances of overlapping isotopic envelopes to be assessed. Repeat units were confirmed and end functionality assigned. Single shot mass spectra of the entire polymeric distribution demonstrate that the dynamic range of this internal MALDI source instrument and the analyzer cell exceeds performance of those previously reported for higher field instruments. Corrections of space charge mass shift effects are demonstrated for the analytes using an external calibrant and (subsequent to confirmation of structure) via internal calibration which removes ambiguity due to space charge differences in calibrant and analyte spectra. Capillary gel permeation chromatography was used to prepare low polydispersity samples from a high polydispersity polyester, improving the measurement of molecular weight distribution two-fold while retaining the benefits of high resolution mass spectrometry for elucidation of oligomer identity.

Matrix-assisted laser desorption/ionization mass spectrometric imaging for the rapid segmental analysis of methamphetamine in a single hair using umbelliferone as a matrix.

Science.gov (United States)

Wang, Hang; Wang, Ying

2017-07-04

Segmental hair analysis offers a longer period for retrospective drug detection than blood or urine. Hair is a keratinous fiber and is strongly hydrophobic. The embedding of drugs in hydrophobic hair at low concentrations makes it difficult for extraction and detection with matrix-assisted laser desorption/ionization (MALDI) coupled with mass spectrometric imaging (MSI). In this study, a single scalp hair was longitudinally cut with a cryostat section to a length of 4 mm and fixed onto a stainless steel MALDI plate. Umbelliferone was used as a new hydrophobic matrix to enrich and assist the ionization efficiency of methamphetamine in the hair sample. MALDI-Fourier transform ion cyclotron resonance (FTICR)-MS profiling and imaging were performed for direct detection and mapping of methamphetamine on the longitudinal sections of the single hair sample in positive ion mode. Using MALDI-MSI, the distribution of methamphetamine was observed throughout five longitudinally sectioned hair samples from a drug abuser. The changes of methamphetamine were also semi-quantified by comparing the ratios of methamphetamine/internal standard (I.S). This method improves the detection sensitivity of target drugs embedded in a hair matrix for imaging with mass spectrometry. The method could provide a detection level of methamphetamine down to a nanogram per milligram incorporated into hair. The results were also compared with the conventional high performance liquid chromatography -tandem mass spectrometry (HPLC-MS/MS) method. Changes in the imaging results over time by the MSI method showed good semi-quantitative correlation to the results from the HPLC-MS/MS method. This study provides a powerful tool for drug abuse control and forensic medicine analysis in a narrow time frame, and a reduction in the sample amount required. Copyright © 2017 Elsevier B.V. All rights reserved.

Assisted inhibition effect of acetylcholinesterase with n-octylphosphonic acid and application in high sensitive detection of organophosphorous pesticides by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry.

Science.gov (United States)

Cai, Tingting; Zhang, Li; Wang, Haoyang; Zhang, Jing; Guo, Yinlong

2011-11-14

A simple and practical approach to improve the sensitivity of acetylcholinesterase (AChE)-inhibited method has been developed for monitoring organophosphorous (OP) pesticide residues. In this work, matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used to detect AChE activity. Due to its good salt-tolerance and low sample consumption, MALDI-FTMS facilitates rapid and high-throughput screening of OP pesticides. Here we describe a new method to obtain low detection limits via employing external reagents. Among candidate compounds, n-octylphosphonic acid (n-Octyl-PA) displays assistant effect to enhance AChE inhibition by OP pesticides. In presence of n-Octyl-PA, the percentages of AChE inhibition still kept correlation with OP pesticide concentrations. The detection limits were improved significantly even by 10(2)-10(3) folds in comparison with conventional enzyme-inhibited methods. Different detection limits of OP pesticides with different toxicities were as low as 0.005 μg L(-1) for high toxic pesticides and 0.05 μg L(-1) for low toxic pesticides. Besides, the reliability of results from this method to analyze cowpea samples had been demonstrated by liquid-chromatography tandem mass spectrometry (LC-MS/MS). The application of this commercial available assistant agent shows great promise to detect OP compounds in complicated biological matrix and broadens the mind for high sensitivity detection of OP pesticide residues in agricultural products. Copyright © 2011 Elsevier B.V. All rights reserved.

Growth of thin films of low molecular weight proteins by matrix assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Matei, Andreea; Schou, Jørgen; Constantinescu, C.

2011-01-01

Thin films of lysozyme and myoglobin grown by matrix assisted pulsed laser evaporation (MAPLE) from a water ice matrix have been investigated. The deposition rate of these two low molecular weight proteins (lysozyme: 14307 amu and myoglobin: 17083 amu) exhibits a maximum of about 1–2 ng/cm2 per....... The results for lysozyme demonstrate that the fragmentation rate of the proteins during the MAPLE process is not influenced by the pH of the water solution prior to freezing....

Characterization of ethylcellulose and hydroxypropyl methylcellulose thin films deposited by matrix-assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Palla-Papavlu, A., E-mail: apalla@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania); Rusen, L.; Dinca, V.; Filipescu, M. [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania); Lippert, T. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania)

2014-05-01

In this study is reported the deposition of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) by matrix-assisted pulsed laser evaporation (MAPLE). Both HPMC and EC were deposited on silicon substrates using a Nd:YAG laser (266 nm, 5 ns laser pulse and 10 Hz repetition rate) and then characterized by atomic force microscopy and Fourier transform infrared spectroscopy. It was found that for laser fluences up to 450 mJ/cm{sup 2} the structure of the deposited HPMC and EC polymer in the thin film resembles to the bulk. Morphological investigations reveal island features on the surface of the EC thin films, and pores onto the HPMC polymer films. The obtained results indicate that MAPLE may be an alternative technique for the fabrication of new systems with desired drug release profile.

Characterization of ethylcellulose and hydroxypropyl methylcellulose thin films deposited by matrix-assisted pulsed laser evaporation

Science.gov (United States)

Palla-Papavlu, A.; Rusen, L.; Dinca, V.; Filipescu, M.; Lippert, T.; Dinescu, M.

2014-05-01

In this study is reported the deposition of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) by matrix-assisted pulsed laser evaporation (MAPLE). Both HPMC and EC were deposited on silicon substrates using a Nd:YAG laser (266 nm, 5 ns laser pulse and 10 Hz repetition rate) and then characterized by atomic force microscopy and Fourier transform infrared spectroscopy. It was found that for laser fluences up to 450 mJ/cm2 the structure of the deposited HPMC and EC polymer in the thin film resembles to the bulk. Morphological investigations reveal island features on the surface of the EC thin films, and pores onto the HPMC polymer films. The obtained results indicate that MAPLE may be an alternative technique for the fabrication of new systems with desired drug release profile.

Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

DEFF Research Database (Denmark)

Rodrigo, K.; Czuba, P.; Toftmann, B.

2006-01-01

The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements...

Detection of Bacteriocins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

OpenAIRE

Rose, Natisha L.; Sporns, Peter; McMullen, Lynn M.

1999-01-01

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection of bacteriocins was investigated. A 30-s water wash of the sample on the MALDI-TOF MS probe was effective in removing contaminants of the analyte. This method was used for rapid detection of nisin, pediocin, brochocin A and B, and enterocin A and B from culture supernatants and for detection of enterocin B throughout its purification.

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.

Fundamentals of laser-assisted fabrication of inorganic and organic films

DEFF Research Database (Denmark)

Schou, Jørgen

2008-01-01

The standard method for producing films by laser-assisted methods, Pulsed Laser Deposition (PLD) will be reviewed. The films considered are usually inorganic films, but also films of organic materials have been produced. Also the deposition of organic films by MAPLE (Matrix Assisted Pulsed Laser...

Benefits of 2.94 μm infrared matrix-assisted laser desorption/ionization for analysis of labile molecules by Fourier transform mass spectrometry

DEFF Research Database (Denmark)

Budnik, Bogdan A.; Jensen, Kenneth Bendix; Jørgensen, Thomas J. D.

2000-01-01

A 2.94 microm Er:YAG laser was used together with a commercial Fourier transform mass spectrometer to study labile biomolecules. The combination has shown superior performance over conventional 337 nm ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) Fourier transform mass...

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....

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.

Direct analysis of triterpenes from high-salt fermented cucumbers using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI)

Science.gov (United States)

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 ioniz...

Generation of CsI cluster ions for mass calibration in matrix-assisted laser desorption/ionization mass spectrometry

NARCIS (Netherlands)

Lou, X.; Dongen, van J.L.J.; Meijer, E.W.

2010-01-01

A simple method was developed for the generation of cesium iodide (CsI) cluster ions up to m/z over 20,000 in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Calibration ions in both positive and negative ion modes can readily be generated from a single MALDI spot of CsI(3)

Application of targeted quantitative proteomics analysis in human cerebrospinal fluid using a liquid chromatography matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometer (LC MALDI TOF/TOF) platform.

Science.gov (United States)

Pan, Sheng; Rush, John; Peskind, Elaine R; Galasko, Douglas; Chung, Kathryn; Quinn, Joseph; Jankovic, Joseph; Leverenz, James B; Zabetian, Cyrus; Pan, Catherine; Wang, Yan; Oh, Jung Hun; Gao, Jean; Zhang, Jianpeng; Montine, Thomas; Zhang, Jing

2008-02-01

Targeted quantitative proteomics by mass spectrometry aims to selectively detect one or a panel of peptides/proteins in a complex sample and is particularly appealing for novel biomarker verification/validation because it does not require specific antibodies. Here, we demonstrated the application of targeted quantitative proteomics in searching, identifying, and quantifying selected peptides in human cerebrospinal spinal fluid (CSF) using a matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometer (MALDI TOF/TOF)-based platform. The approach involved two major components: the use of isotopic-labeled synthetic peptides as references for targeted identification and quantification and a highly selective mass spectrometric analysis based on the unique characteristics of the MALDI instrument. The platform provides high confidence for targeted peptide detection in a complex system and can potentially be developed into a high-throughput system. Using the liquid chromatography (LC) MALDI TOF/TOF platform and the complementary identification strategy, we were able to selectively identify and quantify a panel of targeted peptides in the whole proteome of CSF without prior depletion of abundant proteins. The effectiveness and robustness of the approach associated with different sample complexity, sample preparation strategies, as well as mass spectrometric quantification were evaluated. Other issues related to chromatography separation and the feasibility for high-throughput analysis were also discussed. Finally, we applied targeted quantitative proteomics to analyze a subset of previously identified candidate markers in CSF samples of patients with Parkinson's disease (PD) at different stages and Alzheimer's disease (AD) along with normal controls.

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.

Laser-induced ion emission during polymer deposition from a flash-frozen water ice matrix

DEFF Research Database (Denmark)

Rodrigo, K.; Toftmann, Bo; Schou, Jørgen

2004-01-01

Flash-frozen water solutions of 1% weight PEG (polyethylene glycol) at -50 degreesC were used as targets at a laser wavelength of 355 nm for polymer deposition with Matrix-Assisted Pulsed Laser Evaporation (MAPLE). For medium laser fluences the transfer of PEG material to the substrate was accomp......Flash-frozen water solutions of 1% weight PEG (polyethylene glycol) at -50 degreesC were used as targets at a laser wavelength of 355 nm for polymer deposition with Matrix-Assisted Pulsed Laser Evaporation (MAPLE). For medium laser fluences the transfer of PEG material to the substrate...

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.

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

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...

DIFFERENTIATION OF AEROMONAS ISOLATES OBTAINED FROM DRINKING WATER DISTRIBUTION SYSTEM USING MATRIX-ASSISTED LASER DESCRIPTION/IONIZATION-MASS SPECTROMETRY (MALDI-MS)

Science.gov (United States)

The genus Aeromonas is one of several medically significant genera that have gained prominence due to their evolving taxonomy and controversial role in human diseases. In this study, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was used to analyze the...

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. Graphical Abstract ᅟ.

Study of titania nanorod films deposited by matrix-assisted pulsed laser evaporation as a function of laser fluence

Science.gov (United States)

Caricato, A. P.; Belviso, M. R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Rella, R.; Taurino, A.

2011-11-01

Chemically synthesized brookite titanium dioxide (TiO2) nanorods with average diameter and length dimensions of 3-4 nm and 35-50 nm, respectively, were deposited by the matrix-assisted pulsed laser evaporation technique. A toluene nanorod solution was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser ( λ=248 nm, τ=20 ns) at the repetition rate of 10 Hz, at different fluences (25 to 350 mJ/cm2). The deposited films were structurally characterized by high-resolution scanning and transmission electron microscopy. single-crystal Si wafers and carbon-coated Cu grids were used as substrates. Structural analyses evidenced the occurrence of brookite-phase crystalline nanospheres coexisting with individually distinguishable TiO2 nanorods in the films deposited at fluences varying from 50 to 350 mJ/cm2. Nanostructured TiO2 films comprising only nanorods were deposited by lowering the laser fluence to 25 mJ/cm2. The observed shape and phase transitions of the nanorods are discussed taking into account the laser-induced heating effects, reduced melting temperature and size-dependent thermodynamic stability of nanoscale TiO2.

Nonlinear optical studies on 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

Energy Technology Data Exchange (ETDEWEB)

Matei, Andreea [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Marinescu, Maria, E-mail: maria.marinescu@chimie.unibuc.ro [UB - University of Bucharest, Faculty of Chemistry, 90-92 Şoseaua Panduri, Sector 5, RO-010184, Bucharest (Romania); Constantinescu, Catalin, E-mail: catalin.constantinescu@inflpr.ro [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Ion, Valentin; Mitu, Bogdana [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Ionita, Iulian [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); UB - University of Bucharest, Faculty of Physics, 405 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Dinescu, Maria [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Emandi, Ana [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); UB - University of Bucharest, Faculty of Chemistry, 90-92 Şoseaua Panduri, Sector 5, RO-010184, Bucharest (Romania)

2016-06-30

Graphical abstract: - Highlights: • A newly synthesized ferrocene-derivative exhibits SHG potential. • Matrix-assisted pulsed laser evaporation is employed for thin film fabrication. • The optical properties of the films are investigated, presented and discussed. • At maximum laser output power, the SHG signal is strongly influenced by thin film thickness. - Abstract: We present results on a new, laboratory synthesized ferrocene-derivative, i.e. 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid. Thin films with controlled thickness are deposited by matrix-assisted pulsed laser evaporation (MAPLE), on quartz and silicon substrates, with the aim of evaluating the nonlinear optical properties for potential optoelectronic applications. Dimethyl sulfoxide was used as matrix, with 1% wt. concentration of the guest compound. The frozen target is irradiated by using a Nd:YAG laser (4ω/266 nm, 7 ns pulse duration, 10 Hz repetition rate), at low fluences ranging from 0.1 to 1 J/cm{sup 2}. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to probe the surface morphology of the films. Fourier transform infrared (FTIR) and Raman spectroscopy reveal similar structure of the thin film material when compared to the starting material. The optical properties of the thin films are investigated by spectroscopic-ellipsometry (SE), and the refractive index dependence with respect to temperature is studied. The second harmonic generation (SHG) potential is assessed by using a femtosecond Ti:sapphire laser (800 nm, 60–100 fs pulse duration, 80 MHz repetition rate), at 200 mW maximum output power, revealing that the SHG signal intensity is strongly influenced by the films’ thickness.

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

A novel magnet focusing plate for matrix-assisted laser desorption/ionization analysis of magnetic bead-bound analytes.

Science.gov (United States)

Gode, David; Volmer, Dietrich A

2013-05-15

Magnetic beads are often used for serum profiling of peptide and protein biomarkers. In these assays, the bead-bound analytes are eluted from the beads prior to mass spectrometric analysis. This study describes a novel matrix-assisted laser desorption/ionization (MALDI) technique for direct application and focusing of magnetic beads to MALDI plates by means of dedicated micro-magnets as sample spots. Custom-made MALDI plates with magnetic focusing spots were made using small nickel-coated neodymium micro-magnets integrated into a stainless steel plate in a 16 × 24 (384) pattern. For demonstrating the proof-of-concept, commercial C-18 magnetic beads were used for the extraction of a test compound (reserpine) from aqueous solution. Experiments were conducted to study focusing abilities, the required laser energies, the influence of a matrix compound, dispensing techniques, solvent choice and the amount of magnetic beads. Dispensing the magnetic beads onto the micro-magnet sample spots resulted in immediate and strong binding to the magnetic surface. Light microscope images illustrated the homogeneous distribution of beads across the surfaces of the magnets, when the entire sample volume containing the beads was pipetted onto the surface. Subsequent MALDI analysis of the bead-bound analyte demonstrated excellent and reproducible ionization yields. The surface-assisted laser desorption/ionization (SALDI) properties of the strongly light-absorbing γ-Fe2O3-based beads resulted in similar ionization efficiencies to those obtained from experiments with an additional MALDI matrix compound. This feasibility study successfully demonstrated the magnetic focusing abilities for magnetic bead-bound analytes on a novel MALDI plate containing small micro-magnets as sample spots. One of the key advantages of this integrated approach is that no elution steps from magnetic beads were required during analyses compared with conventional bead experiments. Copyright © 2013 John Wiley

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.

Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites

Science.gov (United States)

Quadrini, Fabrizio; Squeo, Erica Anna; Prosperi, Claudia

2010-01-01

A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force) were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a strong interpenetration of adjacent layers was observed.

Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Rusen, L. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele, Bucharest (Romania); Mitu, B.; Filipescu, M.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania)

2013-08-01

Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm{sup −2}. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

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. Graphical Abstract ᅟ.

Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation Of Inorganic Nanoparticles And Organic/Inorganic Hybrid Nanocomposites

Science.gov (United States)

Pate, Ryan; Lantz, Kevin R.; Dhawan, Anuj; Vo-Dinh, Tuan; Stiff-Roberts, Adrienne D.

2010-10-01

In this research, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been used to deposit different classes of inorganic nanoparticles, including bare, un-encapsulated ZnO and Au nanoparticles, as well as ligand-encapsulated CdSe colloidal quantum dots (CQDs). RIR-MAPLE has been used for thin-film deposition of different organic/inorganic hybrid nanocomposites using some of these inorganic nanoparticles, including CdSe CQD-poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-(1-cyanovinylene)phenylene] (MEH-CN-PPV) nanocomposites and Au nanoparticle-poly(methyl methacrylate) (PMMA) nanocomposites. The unique contribution of this research is that a technique is demonstrated for the deposition of organic-based thin-films requiring solvents with bond energies that do not have to be resonant with the laser energy. By creating an emulsion of solvent and ice in the target, RIR-MAPLE using a 2.94 μm laser can deposit most material systems because the hydroxyl bonds in the ice component of the emulsion matrix are strongly resonant with the 2.94 μm laser. In this way, the types of materials that can be deposited using RIR-MAPLE has been significantly expanded. Furthermore, materials with different solvent bond energies can be co-deposited without concern for material degradation and without the need to specifically tune the laser energy to each material solvent bond energy, thereby facilitating the realization of organic/inorganic hybrid nanocomposite thin-films. In addition to the structural characterization of the inorganic nanoparticle and hybrid nanocomposite thin-films deposited using this RIR-MAPLE technique, optical characterization is presented to demonstrate the potential of such films for optoelectronic device applications.

Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation Of Inorganic Nanoparticles And Organic/Inorganic Hybrid Nanocomposites

International Nuclear Information System (INIS)

Pate, Ryan; Lantz, Kevin R.; Stiff-Roberts, Adrienne D.; Dhawan, Anuj; Vo-Dinh, Tuan

2010-01-01

In this research, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been used to deposit different classes of inorganic nanoparticles, including bare, un-encapsulated ZnO and Au nanoparticles, as well as ligand-encapsulated CdSe colloidal quantum dots (CQDs). RIR-MAPLE has been used for thin-film deposition of different organic/inorganic hybrid nanocomposites using some of these inorganic nanoparticles, including CdSe CQD-poly[2-methoxy-5-(2'-ethylhexyloxy )-1,4-(1-cyanovinylene)phenylene](MEH-CN-PPV) nanocomposites and Au nanoparticle-poly(methyl methacrylate)(PMMA) nanocomposites. The unique contribution of this research is that a technique is demonstrated for the deposition of organic-based thin-films requiring solvents with bond energies that do not have to be resonant with the laser energy. By creating an emulsion of solvent and ice in the target, RIR-MAPLE using a 2.94 μm laser can deposit most material systems because the hydroxyl bonds in the ice component of the emulsion matrix are strongly resonant with the 2.94 μm laser. In this way, the types of materials that can be deposited using RIR-MAPLE has been significantly expanded. Furthermore, materials with different solvent bond energies can be co-deposited without concern for material degradation and without the need to specifically tune the laser energy to each material solvent bond energy, thereby facilitating the realization of organic/inorganic hybrid nanocomposite thin-films. In addition to the structural characterization of the inorganic nanoparticle and hybrid nanocomposite thin-films deposited using this RIR-MAPLE technique, optical characterization is presented to demonstrate the potential of such films for optoelectronic device applications.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: a new possibility for the identification and typing of anaerobic bacteria.

Science.gov (United States)

Nagy, Elizabeth

2014-01-01

Anaerobic bacteria predominate in the normal flora of humans and are important, often life-threatening pathogens in mixed infections originating from the indigenous microbiota. The isolation and identification of anaerobes by phenotypic and DNA-based molecular methods at a species level is time-consuming and laborious. Following the successful adaptation of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the routine laboratory identification of bacteria, the extensive development of a database has been initiated to use this method for the identification of anaerobic bacteria. Not only frequently isolated anaerobic species, but also newly recognized and taxonomically rearranged genera and species can be identified using direct smear samples or whole-cell protein extraction, and even phylogenetically closely related species can be identified correctly by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Typing of anaerobic bacteria on a subspecies level, determination of antibiotic resistance and direct identification of blood culture isolates will revolutionize anaerobe bacteriology in the near future.

Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites

Directory of Open Access Journals (Sweden)

Claudia Prosperi

2010-01-01

Full Text Available A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a stronginterpenetration of adjacent layers was observed.

Uniform thin films of TiO2 nanoparticles deposited by matrix-assisted pulsed laser evaporation

International Nuclear Information System (INIS)

Caricato, A.P.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Spadavecchia, J.; Tunno, T.; Valerini, D.

2007-01-01

We report morphological and optical properties of a colloidal TiO 2 nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1 μm in size was noticed. Form UV-vis transmission spectra, recorded in the 200-800 nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO 2 nanoparticle thin films

Matrix-assisted laser desorption/ionization mass spectrometry for the structural characterization of modified oligonucleotides

International Nuclear Information System (INIS)

Hurst, G.B.; Hettich, R.L.; Buchanan, M.V.; Stemmler, E.A.

1993-01-01

Matrix-assisted laser desorption ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry (FTMS) and MALDI time-of-flight mass spectrometry (TOFMS) are being used to characterize conditions for the efficient desorption and ionization of normal and modified nucleic acid components. Basic and acidic matrix materials have been evaluated on the components. Basic and acidic matrix materials have been evaluated on the FTMS and TOFMS. Using MALDI-FTMS at 355 nm, less fragmentation has been observed using 2,5-dihydroxybenzoic acid, while more extensive fragmentation is observed for basic matrices, such as 1,5-diaminonaphthalene and 9-aminophenanthrene. Elevation of the cell pressure by the addition of Ar or CO 2 provides collisional cooling of desorbed ions, resulting in an enhancement of [M--H] - and structurally significant high-mass fragment ions. Using MALDI-TOFMS at 337 nm, fragmentation is significantly reduced relative to that observed on the FTMS, perhaps as a consequence of the longer times required for FTMS detection. On the FTMS and TOFMS, cluster ions have been observed in the negative ion mode when metal ions are present in the 2,5-dihydroxybenzoic acid matrix. Metal ion additions and clusters with matrix salts have also been observed for dinucleotides. Applications of MALDI-FTMS and MALDI-TOF to the detection of hydroxylated PAH nucleoside adducts are presented

Functionalized porphyrin conjugate thin films deposited by matrix assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Iordache, S. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, A.C.; Popescu, C.E.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Ciucu, A.A. [University of Bucharest, Faculty of Chemistry, Bucharest (Romania); Balan, A.; Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Fagadar-Cosma, E. [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Ave. 24, 300223-Timisoara (Romania); Chrisey, D.B. [Tulane University, Departments of Physics and Biomedical Engineering, New Orleans, LA 70118 (United States)

2013-08-01

We report on the deposition of nanostructured porphyrin-base, 5(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin thin films by matrix assisted pulsed laser evaporation onto silicon substrates with screen-printed electrodes. AFM investigations have shown that at 400 mJ/cm{sup 2} fluence a topographical transition takes place from the platelet-like stacking porphyrin-based nanostructures in a perpendicular arrangement to a quasi-parallel one both relative to the substrate surface. Raman spectroscopy has shown that the chemical structure of the deposited thin films is preserved for fluences within the range of 200–300 mJ/cm{sup 2}. Cyclic voltammograms have demonstrated that the free porphyrin is appropriate as a single mediator for glucose in a specific case of screen-printed electrodes, suggesting potential for designing a new class of biosensors.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry for direct bacterial identification from positive blood culture pellets.

Science.gov (United States)

Prod'hom, Guy; Bizzini, Alain; Durussel, Christian; Bille, Jacques; Greub, Gilbert

2010-04-01

An ammonium chloride erythrocyte-lysing procedure was used to prepare a bacterial pellet from positive blood cultures for direct matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectrometry analysis. Identification was obtained for 78.7% of the pellets tested. Moreover, 99% of the MALDI-TOF identifications were congruent at the species level when considering valid scores. This fast and accurate method is promising.

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…

Photoluminescence of Eu-doped LiYF4 thin films grown by pulsed laser deposition and matrix-assisted pulsed laser evaporation

International Nuclear Information System (INIS)

Stokker-Cheregi, F; Matei, A; Dinescu, M; Secu, C E; Secu, M

2014-01-01

Matrix-assisted pulsed laser evaporation (MAPLE) has been investigated as an alternative to the pulsed laser deposition (PLD) technique for Eu 3+ -doped crystalline LiYF 4 thin-films deposition. MAPLE assumes laser ablation of a frozen target made of the material of interest diluted in a solvent, rather than that of a bulk target, of either pressed powder or single crystal, used in the case of PLD. Our approach stems from the assumption that laser ablation of a frozen dilute target would result in thin films with improved morphology, as compared to PLD. Indeed, we find that roughness values of samples obtained by the MAPLE technique are four times lower than in the case of PLD. A lower transmittance was noticed for PLD obtained layers with respect to those grown by MAPLE due to strong scattering of light by the morphological defects. Photoluminescence spectra are showing characteristic Eu 3+ -ion luminescence bands at 578, 591, 612, 650 and 698 nm ( 5 D 0  →  7 F J ); crystal field splitting of the bands indicates dopant ions incorporation in the host material during transfer by either PLD or MAPLE. (paper)

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.

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

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.

Nanoparticle Thin Films for Gas Sensors Prepared by Matrix Assisted Pulsed Laser Evaporation

Directory of Open Access Journals (Sweden)

Roberto Rella

2009-04-01

Full Text Available The matrix assisted pulsed laser evaporation (MAPLE technique has been used for the deposition of metal dioxide (TiO2, SnO2 nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al2O3 substrates. A rather uniform distribution of TiO2 nanoparticles with an average size of about 10 nm and of SnO2 nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit towards ethanol and acetone are presented.

Nanoparticle thin films for gas sensors prepared by matrix assisted pulsed laser evaporation.

Science.gov (United States)

Caricato, Anna Paola; Luches, Armando; Rella, Roberto

2009-01-01

The matrix assisted pulsed laser evaporation (MAPLE) technique has been used for the deposition of metal dioxide (TiO(2), SnO(2)) nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al(2)O(3) substrates. A rather uniform distribution of TiO(2) nanoparticles with an average size of about 10 nm and of SnO(2) nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG) inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit) towards ethanol and acetone are presented.

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Direct Bacterial Identification from Positive Blood Culture Pellets ▿

OpenAIRE

Prod'hom, Guy; Bizzini, Alain; Durussel, Christian; Bille, Jacques; Greub, Gilbert

2010-01-01

An ammonium chloride erythrocyte-lysing procedure was used to prepare a bacterial pellet from positive blood cultures for direct matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectrometry analysis. Identification was obtained for 78.7% of the pellets tested. Moreover, 99% of the MALDI-TOF identifications were congruent at the species level when considering valid scores. This fast and accurate method is promising.

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.

Organic/hybrid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

Science.gov (United States)

Stiff-Roberts, Adrienne D.; Ge, Wangyao

2017-12-01

Some of the most exciting materials research in the 21st century attempts to resolve the challenge of simulating, synthesizing, and characterizing new materials with unique properties designed from first principles. Achievements in such development for organic and organic-inorganic hybrid materials make them important options for electronic and/or photonic devices because they can impart multi-functionality, flexibility, transparency, and sustainability to emerging systems, such as wearable electronics. Functional organic materials include small molecules, oligomers, and polymers, while hybrid materials include inorganic nanomaterials (such as zero-dimensional quantum dots, one-dimensional carbon nanotubes, or two-dimensional nanosheets) combined with organic matrices. A critically important step to implementing new electronic and photonic devices using such materials is the processing of thin films. While solution-based processing is the most common laboratory technique for organic and hybrid materials, vacuum-based deposition has been critical to the commercialization of organic light emitting diodes based on small molecules, for example. Therefore, it is desirable to explore vacuum-based deposition of organic and hybrid materials that include larger macromolecules, such as polymers. This review article motivates the need for physical vapor deposition of polymeric and hybrid thin films using matrix-assisted pulsed laser evaporation (MAPLE), which is a type of pulsed laser deposition. This review describes the development of variations in the MAPLE technique, discusses the current understanding of laser-target interactions and growth mechanisms for different MAPLE variations, surveys demonstrations of MAPLE-deposited organic and hybrid materials for electronic and photonic devices, and provides a future outlook for the technique.

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.

Design challenges for matrix assisted pulsed laser evaporation and infrared resonant laser evaporation equipment

Science.gov (United States)

Greer, James A.

2011-11-01

Since the development of the Matrix Assisted Pulsed Laser Evaporation (MAPLE) process by the Naval Research Laboratory (NRL) in the late 1990s, MAPLE has become an active area of research for the deposition of a variety of polymer, biological, and organic thin films. As is often the case with advancements in thin-film deposition techniques new technology sometimes evolves by making minor or major adjustments to existing deposition process equipment and techniques. This is usually the quickest and least expensive way to try out new ideas and to "push the envelope" in order to obtain new and unique scientific results as quickly as possible. This process of "tweaking" current equipment usually works to some degree, but once the new process is further refined overall designs for a new deposition tool based on the critical attributes of the new process typically help capitalize more fully on the all the salient features of the new and improved process. This certainly has been true for the MAPLE process. In fact the first MAPLE experiments the polymer/solvent matrix was mixed and poured into a copper holder held at LN2 temperature on a laboratory counter top. The holder was then quickly placed onto a LN2 cooled reservoir in a vacuum deposition chamber and placed in a vertical position on a LN2 cooled stage and pumped down as quickly as possible. If the sample was not placed into the chamber quickly enough the frozen matrix would melt and drip into the bottom of the chamber onto the chambers main gate valve making a bit of a mess. However, skilled and motivated scientists usually worked quickly enough to make this process work most of the time. The initial results from these experiments were encouraging and led to several publications which sparked considerable interest in this newly developed technique Clearly this approach provided the vision that MAPLE was a viable deposition process, but the equipment was not optimal for conducting MAPLE experiments on a regular basis

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.

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry identification of large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G

DEFF Research Database (Denmark)

Salgård Jensen, Christian; Dam-Nielsen, Casper; Arpi, Magnus

2015-01-01

BACKGROUND: The aim of this study was to investigate whether large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G can be adequately identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF). Previous studies show varying...

Quantitative analysis of polyhexamethylene guanidine (PHMG) oligomers via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with an ionic-liquid matrix.

Science.gov (United States)

Yoon, Donhee; Lee, Dongkun; Lee, Jong-Hyeon; Cha, Sangwon; Oh, Han Bin

2015-01-30

Quantifying polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with a conventional crystalline matrix generally suffers from poor sample-to-sample or shot-to-shot reproducibility. An ionic-liquid matrix has been demonstrated to mitigate these reproducibility issues by providing a homogeneous sample surface, which is useful for quantifying polymers. In the present study, we evaluated the use of an ionic liquid matrix, i.e., 1-methylimidazolium α-cyano-4-hydroxycinnamate (1-MeIm-CHCA), to quantify polyhexamethylene guanidine (PHMG) samples that impose a critical health hazard when inhaled in the form of droplets. MALDI-TOF mass spectra were acquired for PHMG oligomers using a variety of ionic-liquid matrices including 1-MeIm-CHCA. Calibration curves were constructed by plotting the sum of the PHMG oligomer peak areas versus PHMG sample concentration with a variety of peptide internal standards. Compared with the conventional crystalline matrix, the 1-MeIm-CHCA ionic-liquid matrix had much better reproducibility (lower standard deviations). Furthermore, by using an internal peptide standard, good linear calibration plots could be obtained over a range of PMHG concentrations of at least 4 orders of magnitude. This study successfully demonstrated that PHMG samples can be quantitatively characterized by MALDI-TOFMS with an ionic-liquid matrix and an internal standard. Copyright © 2014 John Wiley & Sons, Ltd.

Current status of matrix-assisted laser desorption ionisation-time of flight mass spectrometry in the clinical microbiology laboratory.

Science.gov (United States)

Kok, Jen; Chen, Sharon C A; Dwyer, Dominic E; Iredell, Jonathan R

2013-01-01

The integration of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) into many clinical microbiology laboratories has revolutionised routine pathogen identification. MALDI-TOF MS complements and has good potential to replace existing phenotypic identification methods. Results are available in a more clinically relevant timeframe, particularly in bacteraemic septic shock. Novel applications include strain typing and the detection of antimicrobial resistance, but these are not widely used. This review discusses the technical aspects, current applications, and limitations of MALDI-TOF MS.

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.

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

Short communication: Identification of subclinical cow mastitis pathogens in milk by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Barreiro, J R; Ferreira, C R; Sanvido, G B; Kostrzewa, M; Maier, T; Wegemann, B; Böttcher, V; Eberlin, M N; dos Santos, M V

2010-12-01

Subclinical mastitis is a common and easily disseminated disease in dairy herds. Its routine diagnosis via bacterial culture and biochemical identification is a difficult and time-consuming process. In this work, we show that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows bacterial identification with high confidence and speed (1 d for bacterial growth and analysis). With the use of MALDI-TOF MS, 33 bacterial culture isolates from milk of different dairy cows from several farms were analyzed, and the results were compared with those obtained by classical biochemical methods. This proof-of-concept case demonstrates the reliability of MALDI-TOF MS bacterial identification, and its increased selectivity as illustrated by the additional identification of coagulase-negative Staphylococcus species and mixed bacterial cultures. Matrix-assisted laser desorption-ionization mass spectrometry considerably accelerates the diagnosis of mastitis pathogens, especially in cases of subclinical mastitis. More immediate and efficient animal management strategies for mastitis and milk quality control in the dairy industry can therefore be applied. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

Deposition of Methylammonium Lead Triiodide by Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

Science.gov (United States)

Barraza, E. Tomas; Dunlap-Shohl, Wiley A.; Mitzi, David B.; Stiff-Roberts, Adrienne D.

2018-02-01

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) was used to deposit the metal-halide perovskite (MHP) CH3NH3PbI3 (methylammonium lead triiodide, or MAPbI), creating phase-pure films. Given the moisture sensitivity of these crystalline, multi-component organic-inorganic hybrid materials, deposition of MAPbI by RIR-MAPLE required a departure from the use of water-based emulsions as deposition targets. Different chemistries were explored to create targets that properly dissolved MAPbI components, were stable under vacuum conditions, and enabled resonant laser energy absorption. Secondary phases and solvent contamination in the resulting films were studied through Fourier transform infrared (FTIR) absorbance and x-ray diffraction (XRD) measurements, suggesting that lingering excess methylammonium iodide (MAI) and low-vapor pressure solvents can distort the microstructure, creating crystalline and amorphous non-perovskite phases. Thermal annealing of films deposited by RIR-MAPLE allowed for excess solvent to be evaporated from films without degrading the MAPbI structure. Further, it was demonstrated that RIR-MAPLE does not require excess MAI to create stoichiometric films with optoelectronic properties, crystal structure, and film morphology comparable to films created using more established spin-coating methods for processing MHPs. This work marks the first time a MAPLE-related technique was used to deposit MHPs.

Influence of Culture Media on Detection of Carbapenem Hydrolysis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

Science.gov (United States)

Ramos, Ana Carolina; Carvalhaes, Cecília Godoy; Cordeiro-Moura, Jhonatha Rodrigo; Rockstroh, Anna Carolina; Machado, Antonia Maria Oliveira; Gales, Ana Cristina

2016-07-01

In this study, we evaluated the influence of distinct bacterial growth media on detection of carbapenemase hydrolysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. False-negative results were observed for OXA-25-, OXA-26-, and OXA-72-producing Acinetobacter baumannii isolates grown on MacConkey agar medium. The other culture media showed 100% sensitivity and 100% specificity for detecting carbapenemase. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Rapid and efficient proteolysis through laser-assisted immobilized enzyme reactors.

Science.gov (United States)

Zhang, Peng; Gao, Mingxia; Zhu, Shaochun; Lei, Jie; Zhang, Xiangmin

2011-11-25

In this report, laser radiation (808nm) for the first time was employed to enhance the efficiency of proteolysis through immobilized enzyme reactor (IMER). IMER based monolithic support was prepared in the fused-silica capillary via a simple two-step procedure including acryloylation on trypsin surface and in situ aqueous polymerization/immobilization. The feasibility and high efficiency of the laser-assisted IMER were demonstrated by the digestion of bovine serum albumin (BSA), cytochrome c (Cyt-c) and β-casein. The digestion process was achieved in 60s. The peptides were identified by MALDI-TOF-MS, yielding the sequence coverage of 33% for BSA, 73% for Cyt-c and 22% for β-casein. The comparisons between the in-solution digestion and on IMER reaction with/without laser assistance were made. To further confirm its efficiency in proteome analysis, the laser-assisted IMER was also applied to the analysis of one fraction of human serum sample through two-dimensional (2-D) separation of strong anion exchange/reversed-phase liquid chromatography (SAX/RPLC). After a database search, 49 unique peptides corresponding to 5 proteins were identified. The results showed that the laser-assisted IMER provides a promising platform for the high-throughput protein identification. Copyright © 2011 Elsevier B.V. All rights reserved.

Mass spectrometry imaging of illicit drugs in latent fingerprints by matrix-free and matrix-assisted desorption/ionization techniques.

Science.gov (United States)

Skriba, Anton; Havlicek, Vladimir

2018-02-01

Compared with classical matrix-assisted laser-desorption ionization mass spectrometry (MALDI), the matrix free-based strategies generate a cleaner background, without significant noise or interference coming from an applied matrix, which is beneficial for the analysis of small molecules, such as drugs of abuse. In this work, we probed the detection efficiency of methamphetamine, heroin and cocaine in nanostructure-assisted laser desorption-ionization (NALDI) and desorption electrospray ionization and compared the sensitivity of these two matrix-free tools with a standard MALDI mass spectrometry experiment. In a typical mass spectrometry imaging (MSI) setup, papillary line latent fingerprints were recorded as a mixture a common skin fatty acid or interfering cosmetics with a drug. In a separate experiment, all drugs (1 µL of 1 μM standard solution) were detected by all three ionization techniques on a target. In the case of cocaine and heroin, NALDI mass spectrometry was the most sensitive and revealed signals even from 0.1 μM solution. The drug/drug contaminant (fatty acid or cosmetics) MSI approach could be used by law enforcement personnel to confirm drug abusers of having come into contact with the suspected drug by use of fingerprint scans at time of apprehension which can aid in reducing the work of lab officials.

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry for caspofungin susceptibility testing of Candida and Aspergillus species.

Science.gov (United States)

De Carolis, Elena; Vella, Antonietta; Florio, Ada R; Posteraro, Patrizia; Perlin, David S; Sanguinetti, Maurizio; Posteraro, Brunella

2012-07-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated for testing susceptibility to caspofungin of wild-type and fks mutant isolates of Candida and Aspergillus. Complete essential agreement was observed with the CLSI reference method, with categorical agreement for 94.1% of the Candida isolates tested. Thus, MALDI-TOF MS is a reliable and accurate method to detect fungal isolates with reduced caspofungin susceptibility.

Emerging and Future Applications of Matrix-Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry in the Clinical Microbiology Laboratory: A Report of the Association for Molecular Pathology.

Science.gov (United States)

Doern, Christopher D; Butler-Wu, Susan M

2016-11-01

The performance of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MS) for routine bacterial and yeast identification as well as direct-from-blood culture bottle identification has been thoroughly evaluated in the peer-reviewed literature. Microbiologists are now moving beyond these methods to apply MS to other areas of the diagnostic process. This review discusses the emergence of advanced matrix-assisted laser desorption ionization time-of-flight MS applications, including the identification of filamentous fungi and mycobacteria and the current and future state of antimicrobial resistance testing. Copyright © 2016 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

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.

Distribution of erlotinib in rash and normal skin in cancer patients receiving erlotinib visualized by matrix assisted laser desorption/ionization mass spectrometry imaging.

Science.gov (United States)

Nishimura, Meiko; Hayashi, Mitsuhiro; Mizutani, Yu; Takenaka, Kei; Imamura, Yoshinori; Chayahara, Naoko; Toyoda, Masanori; Kiyota, Naomi; Mukohara, Toru; Aikawa, Hiroaki; Fujiwara, Yasuhiro; Hamada, Akinobu; Minami, Hironobu

2018-04-06

The development of skin rashes is the most common adverse event observed in cancer patients treated with epidermal growth factor receptor-tyrosine kinase inhibitors such as erlotinib. However, the pharmacological evidence has not been fully revealed. Erlotinib distribution in the rashes was more heterogeneous than that in the normal skin, and the rashes contained statistically higher concentrations of erlotinib than adjacent normal skin in the superficial skin layer (229 ± 192 vs. 120 ± 103 ions/mm 2 ; P = 0.009 in paired t -test). LC-MS/MS confirmed that the concentration of erlotinib in the skin rashes was higher than that in normal skin in the superficial skin layer (1946 ± 1258 vs. 1174 ± 662 ng/cm 3 ; P = 0.028 in paired t -test). The results of MALDI-MSI and LC-MS/MS were well correlated (coefficient of correlation 0.879, P distribution of erlotinib in the skin tissue was visualized using non-labeled MALDI-MSI. Erlotinib concentration in the superficial layer of the skin rashes was higher than that in the adjacent normal skin. We examined patients with advanced pancreatic cancer who developed skin rashes after treatment with erlotinib and gemcitabine. We biopsied both the rash and adjacent normal skin tissues, and visualized and compared the distribution of erlotinib within the skin using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). The tissue concentration of erlotinib was also measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with laser microdissection.

Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Caspofungin Susceptibility Testing of Candida and Aspergillus Species

Science.gov (United States)

De Carolis, Elena; Vella, Antonietta; Florio, Ada R.; Posteraro, Patrizia; Perlin, David S.; Posteraro, Brunella

2012-01-01

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for testing susceptibility to caspofungin of wild-type and fks mutant isolates of Candida and Aspergillus. Complete essential agreement was observed with the CLSI reference method, with categorical agreement for 94.1% of the Candida isolates tested. Thus, MALDI-TOF MS is a reliable and accurate method to detect fungal isolates with reduced caspofungin susceptibility. PMID:22535984

Semiconductor Nanomaterials-Based Fluorescence Spectroscopic and Matrix-Assisted Laser Desorption/Ionization (MALDI Mass Spectrometric Approaches to Proteome Analysis

Directory of Open Access Journals (Sweden)

Suresh Kumar Kailasa

2013-12-01

Full Text Available Semiconductor quantum dots (QDs or nanoparticles (NPs exhibit very unusual physico-chemcial and optical properties. This review article introduces the applications of semiconductor nanomaterials (NMs in fluorescence spectroscopy and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS for biomolecule analysis. Due to their unique physico-chemical and optical properties, semiconductors NMs have created many new platforms for investigating biomolecular structures and information in modern biology. These semiconductor NMs served as effective fluorescent probes for sensing proteins and cells and acted as affinity or concentrating probes for enriching peptides, proteins and bacteria proteins prior to MALDI-MS analysis.

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…

In Situ Analysis of Bacterial Lipopeptide Antibiotics by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Science.gov (United States)

Debois, Delphine; Ongena, Marc; Cawoy, Hélène; De Pauw, Edwin

2016-01-01

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a technique developed in the late 1990s enabling the two-dimensional mapping of a broad variety of biomolecules present at the surface of a sample. In many applications including pharmaceutical studies or biomarker discovery, the distribution of proteins, lipids or drugs, and metabolites may be visualized within tissue sections. More recently, MALDI MSI has become increasingly applied in microbiology where the versatility of the technique is perfectly suited to monitor the metabolic dynamics of bacterial colonies. The work described here is focused on the application of MALDI MSI to map secondary metabolites produced by Bacilli, especially lipopeptides, produced by bacterial cells during their interaction with their environment (bacteria, fungi, plant roots, etc.). This chapter addresses the advantages and challenges that the implementation of MALDI MSI to microbiological samples entails, including detailed protocols on sample preparation (from both microbiologist and mass spectrometrist points of view), matrix deposition, and data acquisition and interpretation. Lipopeptide images recorded from confrontation plates are also presented.

Identification of barley and rye varieties using matrix- assisted laser desorption/ionisation time-of-flight mass spectrometry with neural networks

DEFF Research Database (Denmark)

Bloch, H.A.; Petersen, Marianne Kjerstine; Sperotto, Maria Maddalena

2001-01-01

developed, which combines analysis of alcohol-soluble wheat proteins (gliadins) using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry with neural networks. Here we have applied the same method for the identification of both barley (Hordeum vulgare L.) and rye (Secale cereale L.......) varieties. For barley, 95% of the mass spectra were correctly classified. This is an encouraging result, since in earlier experiments only a grouping into subsets of varieties was possible. However, the method was not useful in the classification of rye, due to the strong similarity between mass spectra...

Detection and quantification of neurotensin in human brain tissue by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

DEFF Research Database (Denmark)

Gobom, J; Kraeuter, K O; Persson, R

2000-01-01

A method was developed for mass spectrometric detection of neurotensin (NT)-like immunoreactivity and quantification of NT in human brain tissue. The method is based on immunoprecipitation followed by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF......-MS). The identity of the major component of the immunoprecipitates as neurotensin was confirmed by fragment ion analysis on an electrospray ionization quadrupole time-of-flight instrument. MALDI-TOF-MS quantification of NT was achieved using stable-isotope-labeled NT as the internal standard, yielding an error...

A novel type of matrix for surface-assisted laser desorption-ionization mass spectrometric detection of biomolecules using metal-organic frameworks.

Science.gov (United States)

Fu, Chien-Ping; Lirio, Stephen; Liu, Wan-Ling; Lin, Chia-Her; Huang, Hsi-Ya

2015-08-12

A 3D metal-organic framework (MOF) nanomaterial as matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and tandem mass spectrometry (MS/MS) was developed for the analysis of complex biomolecules. Unlike other nanoparticle matrices, this MOF nanomaterial does not need chemical modification prior to use. An exceptional signal reproducibility as well as very low background interferences in analyzing mono-/di-saccharides, peptides and complex starch digests demonstrate its high potential for biomolecule assays, especially for small molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser-assisted fabrication of materials

CERN Document Server

Manna, Indranil

2013-01-01

Laser assisted fabrication involves shaping of materials using laser as a source of heat. It can be achieved by removal of materials (laser assisted cutting, drilling, etc.), deformation (bending, extrusion), joining (welding, soldering) and addition of materials (surface cladding or direct laser cladding). This book on ´Laser assisted Fabrication’ is aimed at developing in-depth engineering concepts on various laser assisted macro and micro-fabrication techniques with the focus on application and a review of the engineering background of different micro/macro-fabrication techniques, thermal history of the treated zone and microstructural development and evolution of properties of the treated zone.

Minimizing matrix effect by femtosecond laser ablation and ionization in elemental determination.

Science.gov (United States)

Zhang, Bochao; He, Miaohong; Hang, Wei; Huang, Benli

2013-05-07

Matrix effect is unavoidable in direct solid analysis, which usually is a leading cause of the nonstoichiometric effect in quantitative analysis. In this research, experiments were carried out to study the overall characteristics of atomization and ionization in laser-solid interaction. Both nanosecond (ns) and femtosecond (fs) lasers were applied in a buffer-gas-assisted ionization source coupled with an orthogonal time-of-flight mass spectrometer. Twenty-nine solid standards of ten different matrices, including six metals and four dielectrics, were analyzed. The results indicate that the fs-laser mode offers more stable relative sensitivity coefficients (RSCs) with irradiance higher than 7 × 10(13) W·cm(-2), which could be more reliable in the determination of element composition of solids. The matrix effect is reduced by half when the fs-laser is employed, owing to the fact that the fs-laser ablation and ionization (fs-LAI) incurs an almost heat-free ablation process and creates a dense plasma for the stable ionization.

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

for serum protein profiling we investigated a range of sample preparation techniques and developed a statistical method based on repeated analyses for evaluation of protein-profiling performance of MALDI MS. Two different solid-phase extraction (SPE) methods were investigated, namely custom......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......-made microcolumns and commercially available magnetic beads. Using these two methods, nineteen different sample preparation methods for serum profiling by MALDI MS were systematically tested with regard to matrix selection, stationary phase, selectivity, and reproducibility. Microcolumns were tested with regard...

Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

Energy Technology Data Exchange (ETDEWEB)

Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

2014-02-15

Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

International Nuclear Information System (INIS)

Visan, A.; Grossin, D.; Stefan, N.; Duta, L.; Miroiu, F.M.; Stan, G.E.; Sopronyi, M.; Luculescu, C.; Freche, M.; Marsan, O.; Charvilat, C.; Ciuca, S.; Mihailescu, I.N.

2014-01-01

Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ FWHM ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite

Ceria nanocubic-ultrasonication assisted dispersive liquid-liquid microextraction coupled with matrix assisted laser desorption/ionization mass spectrometry for pathogenic bacteria analysis.

Science.gov (United States)

Abdelhamid, Hani Nasser; Bhaisare, Mukesh L; Wu, Hui-Fen

2014-03-01

A new ceria (CeO2) nanocubic modified surfactant is used as the basis of a novel nano-based microextraction technique for highly sensitive detection of pathogenic bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). The technique uses ultrasound enhanced surfactant-assisted dispersive liquid-liquid microextraction (UESA-DLLME) with and without ceria (CeO2) followed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). In order to achieve high separation efficiency, we investigated the influential parameters, including extraction time of ultrasonication, type and volume of the extraction solvent and surfactant. Among various surfactants, the cationic surfactants can selectively offer better extraction efficiency on bacteria analysis than that of the anionic surfactants due to the negative charges of bacteria cell membranes. Extractions of the bacteria lysate from aqueous samples via UESA-DLLME-MALDI-MS were successfully achieved by using cetyltrimethyl ammonium bromide (CTAB, 10.0 µL, 1.0×10(-3) M) as surfactants in chlorobenzene (10.0 µL) and chloroform (10.0 µL) as the optimal extracting solvent for P. aeruginosa and S. aureus, respectively. Ceria nanocubic was synthesized, and functionalized with CTAB (CeO2@CTAB) and then characterized using transmission electron microscopy (TEM) and optical spectroscopy (UV and FTIR). CeO2@CTAB demonstrates high extraction efficiency, improve peaks ionization, and enhance resolution. The prime reasons for these improvements are due to the large surface area of nanoparticles, and its absorption that coincides with the wavelength of MALDI laser (337 nm, N2 laser). CeO2@CTAB-based microextraction offers lowest detectable concentrations tenfold lower than that of without nanoceria. The present approach has been successfully applied to detect pathogenic bacteria at low concentrations of 10(4)-10(5) cfu/mL (without ceria) and at 10(3)-10(4) cfu/mL (with ceria) from bacteria suspensions. Finally, the

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...... matrix to the organic solvent enhanced the efficiency of the LLE-MALDI MS method for analysis of hydrophobic peptides and proteins. LLE-MALDI MS enabled the detection of the hydrophobic membrane protein bacteriorhodopsin as a component in a simple protein mixture. Peptide mixtures containing...... phosphorylated, glycosylated, or acylated peptides were successfully separated and analyzed by the in situ LLE-MALDI MS technique and demonstrate the potential of this method for enhanced separation and structural analysis of posttranslationally modified peptides in proteomics research....

Influence of secondary structure on in-source decay of protein in matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Takayama, Mitsuo; Osaka, Issey; Sakakura, Motoshi

2012-01-01

The susceptibility of the N-Cα bond of the peptide backbone to specific cleavage by in-source decay (ISD) in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was studied from the standpoint of the secondary structure of three proteins. A naphthalene derivative, 5-amino-1-naphtol (5,1-ANL), was used as the matrix. The resulting c'-ions, which originate from the cleavage at N-Cα bonds in flexible secondary structures such as turn and bend, and are free from intra-molecular hydrogen-bonded α-helix structure, gave relatively intense peaks. Furthermore, ISD spectra of the proteins showed that the N-Cα bonds of specific amino acid residues, namely Gly-Xxx, Xxx-Asp, and Xxx-Asn, were more susceptible to MALDI-ISD than other amino acid residues. This is in agreement with the observation that Gly, Asp and Asn residues usually located in turns, rather than α-helix. The results obtained indicate that protein molecules embedded into the matrix crystal in the MALDI experiments maintain their secondary structures as determined by X-ray crystallography, and that MALDI-ISD has the capability for providing information concerning the secondary structure of protein.

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...... microL) of a concentrated suspension of isolated chlorosomes directly to the target of the mass spectrometer we have been able to detect bacteriochlorophyll a and all the major homologs of bacteriochlorophyll c. The peak heights of the different bacteriochlorophyll c homologs in the MALDI spectra were...... proportional to peak areas obtained from HPLC analysis of the same sample. The same result was also obtained when whole cells of Chl. tepidum were applied to the target, indicating that MALDI-MS can provide a rapid method for obtaining a semiquantitative determination or finger-print of the bacteriochlorophyll...

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.

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.

Fundamental study of hydrogen-attachment-induced peptide fragmentation occurring in the gas phase and during the matrix-assisted laser desorption/ionization process.

Science.gov (United States)

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

2018-05-09

Mass spectrometry with hydrogen-radical-mediated fragmentation techniques has been used for the sequencing of proteins/peptides. The two methods, matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) and hydrogen attachment/abstraction dissociation (HAD) are known as hydrogen-radical-mediated fragmentation techniques. MALDI-ISD occurs during laser induced desorption processes, whereas HAD utilizes the association of hydrogen with peptide ions in the gas phase. In this study, the general mechanisms of MALDI-ISD and HAD of peptides were investigated. We demonstrated the fragmentation of four model peptides and investigated the fragment formation pathways using density functional theory (DFT) calculations. The current experimental and computational joint study indicated that MALDI-ISD and HAD produce aminoketyl radical intermediates, which immediately undergo radical-induced cleavage at the N-Cα bond located on the C-terminal side of the radical site, leading to the c'/z˙ fragment pair. In the case of MALDI-ISD, the z˙ fragments undergo a subsequent reaction with the matrix to give z' and matrix adducts of the z fragments. In contrast, the c' and z˙ fragments react with hydrogen atoms during the HAD processes, and various fragment species, such as c˙, c', z˙ and z', were observed in the HAD-MS/MS mass spectra.

Performance of matrix-assisted laser desorption-time of flight mass spectrometry for identification of clinical yeast isolates

DEFF Research Database (Denmark)

Rosenvinge, Flemming S; Dzajic, Esad; Knudsen, Elisa

2013-01-01

Accurate and fast yeast identification is important when treating patients with invasive fungal disease as susceptibility to antifungal agents is highly species related. Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) provides a powerful tool with a clear potential...... spectra output, all 13 isolates were correctly identified, resulting in an overall identification performance of 92%. No misidentifications occurred with the two systems. Of the routine isolates one laboratory identified 99/99 (100%) and 90/99 (91%) to species level by Saramis/Axima and conventional...... identification, respectively, whereas the other laboratory identified 83/98 (85%) to species level by both BioTyper/Bruker and conventional identification. Both MALDI-TOF-MS systems are fast, have built-in databases that cover the majority of clinically relevant Candida species, and have an accuracy...

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...

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.

Determination of ibuprofen enantiomers in breast milk using vortex-assisted matrix solid-phase dispersion and direct chiral liquid chromatography.

Science.gov (United States)

León-González, M E; Rosales-Conrado, N

2017-09-08

A mixture of β-cyclodextrin (β-CD) and primary and secondary amine (PSA) sorbents was employed for the extraction and quantification of ibuprofen enantiomers from human breast milk, combining a vortex-assisted matrix solid-phase dispersion method (MSPD) and direct chiral liquid chromatography (CLC) with ultraviolet detection (UV). The MSPD sample preparation procedure was optimized focusing on both the type and amount of dispersion/sorption sorbents and the nature of the elution solvent, in order to obtain acceptable recoveries and avoiding enantiomer conversion. These MSPD parameters were optimized with the aid of an experimental design approach. Hence, a factorial design was used for identification of the main variables affecting the extraction process of ibuprofen enantiomers. Under optimum selected conditions, MSPD combined with direct CLC-UV was successfully applied for ibuprofen enantiomeric determination in breast milk at enantiomer levels between 0.15 and 6.0μgg -1 . The proposed analytical method also provided good repeatability, with relative standard deviations of 6.4% and 8.3% for the intra-day and inter-day precision, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Nanocomposited coatings produced by laser-assisted process to prevent silicone hydogels from protein fouling and bacterial contamination

International Nuclear Information System (INIS)

Huang, Guobang; Chen, Yi; Zhang, Jin

2016-01-01

Graphical abstract: Nanocomposited-coating was deposited on silicone hydrogel by using the matrix-assisted pulsed laser evaporation (MAPLE) process. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel, and can inhibit the bacterial growth efficiently. - Highlights: • We developed a nanocomposited coating to prevent silicone hydrogel from biofouling. • Matrix-assisted pulsed laser evaporation can deposit inorganic–organic nanomaterials. • The designed nanocomposited coating reduces protein absorption by over 50%. • The designed nanocomposited coating shows significant antimicrobial efficiency. - Abstract: Zinc oxide (ZnO) nanoparticles incorporating with polyethylene glycol (PEG) were deposited together on the surface of silicone hydrogel through matrix-assisted pulsed laser evaporation (MAPLE). In this process, frozen nanocomposites (ZnO–PEG) in isopropanol were irradiated under a pulsed Nd:YAG laser at 532 nm for 1 h. Our results indicate that the MAPLE process is able to maintain the chemical backbone of polymer and prevent the nanocomposite coating from contamination. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel. The cytotoxicity study shows that the ZnO–PEG nanocomposites deposited on silicone hydrogels do not impose the toxic effect on mouse NIH/3T3 cells. In addition, MAPLE-deposited ZnO–PEG nanocomposites can inhibit the bacterial growth significantly.

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 to o...... and saponins in legume species, combing the spatially resolved chemical information with morphological details at the microscopic level. Furthermore, the technique offers a scheme capable of high-throughput profiling of metabolites in plant tissues....

Study of temperature dependence and angular distribution of poly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

International Nuclear Information System (INIS)

Caricato, A.P.; Anni, M.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Tunno, T.; Valerini, D.

2009-01-01

Poly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on Si substrates at different temperatures (-16, 30, 50 and 70 deg. C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 deg. C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material.

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

Femtosecond-laser assisted cell reprogramming

Science.gov (United States)

Breunig, Hans Georg; Uchugonova, Aisada; Batista, Ana; König, Karsten

2017-02-01

Femtosecond-laser pulses can assist to transfect cells by creating transient holes in the cell membrane, thus making them temporarily permeable for extraneous genetic material. This procedure offers the advantage of being completely "virus free" since no viruses are used for the delivery and integration of gene factors into the host genome and, thereby, avoiding serious side effects which so far prevent clinical application. Unfortunately, focusing of the laser radiation onto individual cell membranes is quite elaborate and time consuming. Regarding these obstacles, we briefly review two optical setups for fast, efficient and high throughput laser-assisted cell transfection based on femtosecond laser pulse excitation. The first setup aims at assisting the transfection of adherent cells. It comprises of a modified laser-scanning microscope with beamshaping optics as well as home-made software to automate the detection, targeting and laser-irradiation process. The second setup aims at laser-assisted transfection of non-adherent cells in suspension which move in a continuous flow through the laser focus region. The setup allows to address a large number of cells, however, with much lower transfection efficiency than the individual-cell targeting approach.

Transcanalicular laser-assisted dacryocystorhinostomy.

Science.gov (United States)

Rosen, N; Barak, A; Rosner, M

1997-09-01

Current techniques of laser-assisted dacryocystorhinostomy are mostly endonasal. In this report, the authors describe their technique of laser-assisted dacryocystorhinostomy performed through the canaliculi and the surgical results they achieved. Fourteen patients with nasolacrimal duct obstruction underwent transcanalicular laser-assisted dacryocystorhinostomy. The bony ostium was perforated using a fiber optic-transmitting, giant-pulse Nd:YAG laser, with an energy of 0.5 to 4 J per pulse. The total energy used to create an ostium was 18 to 34 J. A silicone tube was inserted through the canaliculi and the ostium into the nasal cavity and kept in place for 5 to 7 months. Patients were observed for 18 to 22 months. Nine of the 14 patients (64%) reported the disappearance of epiphora following surgery. In 3 patients, no relief of epiphora was obtained. In 1 patient the operation was not completed because of severe nasal bleeding. In another, tearing began 12 months after surgery (6 months after tube removal). Transcanalicular laser-assisted dacryocystorhinostomy is a potentially useful method for performing dacryocystorhinostomy. Technical modifications and improvements are needed to increase the success rate.

Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

Directory of Open Access Journals (Sweden)

Chih-Ping Yen

2016-08-01

Full Text Available The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP, and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE for application to dye-sensitized solar cell (DSSC is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

Capsule Typing of Haemophilus influenzae by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

Science.gov (United States)

Månsson, Viktor; Gilsdorf, Janet R; Kahlmeter, Gunnar; Kilian, Mogens; Kroll, J Simon; Riesbeck, Kristian; Resman, Fredrik

2018-03-01

Encapsulated Haemophilus influenzae strains belong to type-specific genetic lineages. Reliable capsule typing requires PCR, but a more efficient method would be useful. We evaluated capsule typing by using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Isolates of all capsule types (a-f and nontypeable; n = 258) and isogenic capsule transformants (types a-d) were investigated. Principal component and biomarker analyses of mass spectra showed clustering, and mass peaks correlated with capsule type-specific genetic lineages. We used 31 selected isolates to construct a capsule typing database. Validation with the remaining isolates (n = 227) showed 100% sensitivity and 92.2% specificity for encapsulated strains (a-f; n = 61). Blinded validation of a supplemented database (n = 50) using clinical isolates (n = 126) showed 100% sensitivity and 100% specificity for encapsulated strains (b, e, and f; n = 28). MALDI-TOF mass spectrometry is an accurate method for capsule typing of H. influenzae.

Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Yen, Chih-Ping [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Yu, Pin-Feng [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Wang, Jyhpyng [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China); Lin, Jiunn-Yuan [Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Chen, Yen-Mu [SuperbIN Co., Ltd., Taipei 114, Taiwan (China); Chen, Szu-yuan, E-mail: sychen@ltl.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China)

2016-08-15

The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP), and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE) for application to dye-sensitized solar cell (DSSC) is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

Composite biocompatible hydroxyapatite-silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation

International Nuclear Information System (INIS)

Miroiu, F.M.; Socol, G.; Visan, A.; Stefan, N.; Craciun, D.; Craciun, V.; Dorcioman, G.; Mihailescu, I.N.; Sima, L.E.; Petrescu, S.M.; Andronie, A.; Stamatin, I.; Moga, S.; Ducu, C.

2010-01-01

The aim of this study was to obtain biomimetic inorganic-organic thin films as coatings for metallic medical implants. These contain hydroxyapatite, the inorganic component of the bony tissues, and a natural biopolymer - silk fibroin - added in view to induce the surface functionalization. Hydroxyapatite (HA), silk fibroin (FIB) and composite HA-FIB films were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in order to compare their physical and biological performances as coatings on metallic prostheses. We used an excimer laser source (KrF*, λ = 248 nm, τ = 25 ns) operated at 10 Hz repetition rate. Coatings were deposited on quartz, Si and Ti substrates and then subjected to physical (FTIR, XRD, AFM, SEM) analyses, correlated with the results of the cytocompatibility in vitro tests. The hybrid films were synthesized from frozen targets of aqueous suspensions with 3:2 or 3:4 weight ratio of HA:FIB. An appropriate stoichiometric and functional transfer was obtained for 0.4-0.5 J/cm 2 laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm -1 amide II, 1654 cm -1 amide I, 1243 cm -1 amide III, while the peak from 1027 cm -1 appeared only for HA and composite films. Osteosarcoma SaOs2 cells cultured 72 h on FIB and HA-FIB films showed increased viability, good spreading and normal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

Composite biocompatible hydroxyapatite-silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation

Energy Technology Data Exchange (ETDEWEB)

Miroiu, F.M., E-mail: marimona.miroiu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Socol, G.; Visan, A.; Stefan, N.; Craciun, D.; Craciun, V.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Sima, L.E.; Petrescu, S.M. [Institute of Biochemistry, Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest (Romania); Andronie, A.; Stamatin, I. [3Nano-SAE Alternative Energy Sources-University of Bucharest, Faculty of Physics, 409 Atomistilor Street, RO-77125, Magurele-Ilfov (Romania); Moga, S.; Ducu, C. [University of Pitesti, Targul din Vale Str, no. 1, 110040 Pitesti (Romania)

2010-05-25

The aim of this study was to obtain biomimetic inorganic-organic thin films as coatings for metallic medical implants. These contain hydroxyapatite, the inorganic component of the bony tissues, and a natural biopolymer - silk fibroin - added in view to induce the surface functionalization. Hydroxyapatite (HA), silk fibroin (FIB) and composite HA-FIB films were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in order to compare their physical and biological performances as coatings on metallic prostheses. We used an excimer laser source (KrF*, {lambda} = 248 nm, {tau} = 25 ns) operated at 10 Hz repetition rate. Coatings were deposited on quartz, Si and Ti substrates and then subjected to physical (FTIR, XRD, AFM, SEM) analyses, correlated with the results of the cytocompatibility in vitro tests. The hybrid films were synthesized from frozen targets of aqueous suspensions with 3:2 or 3:4 weight ratio of HA:FIB. An appropriate stoichiometric and functional transfer was obtained for 0.4-0.5 J/cm{sup 2} laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm{sup -1} amide II, 1654 cm{sup -1} amide I, 1243 cm{sup -1} amide III, while the peak from 1027 cm{sup -1} appeared only for HA and composite films. Osteosarcoma SaOs2 cells cultured 72 h on FIB and HA-FIB films showed increased viability, good spreading and normal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

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.

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.

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.

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...

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.

2016-01-01

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). PMID:27252460

Novel, Improved Sample Preparation for Rapid, Direct Identification from Positive Blood Cultures Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry

OpenAIRE

Schubert, Sören; Weinert, Kirsten; Wagner, Chris; Gunzl, Beatrix; Wieser, Andreas; Maier, Thomas; Kostrzewa, Markus

2011-01-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used for rapid and reliable identification of bacteria and yeast grown on agar plates. Moreover, MALDI-TOF MS also holds promise for bacterial identification from blood culture (BC) broths in hospital laboratories. The most important technical step for the identification of bacteria from positive BCs by MALDI-TOF MS is sample preparation to remove blood cells and host proteins. We present a m...

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.

The influence of wavelength, temporal sequencing, and pulse duration on resonant infrared matrix-assisted laser processing of polymer films

Science.gov (United States)

O'Malley, S. M.; Schoeffling, Jonathan; Jimenez, Richard; Zinderman, Brian; Yi, SunYong; Bubb, D. M.

2014-06-01

We have carried out a systematic investigation of laser ablation plume interactions in resonant infrared matrix-assisted pulsed laser evaporation. The laser source utilized in this study was a mid-infrared OPO capable of dual sequential ns pulses with adjustable delay ranging from 1 to 100 μs. This unique capability enabled us both to probe the ablation plume with a second laser pulse, and to effectively double the laser fluence. The primary ablation target used for this study consisted of poly(methyl methacrylate) dissolved in a binary mixture of methanol and toluene. Both the critical thermodynamic and optical properties of the binary mixture were determined and used to interpret our results. We found that deposition rates associated with single pulse irradiation tracks with the optical absorption coefficient in the spectral range from 2,700 to 3,800 nm. In the case of dual sequential pulses, discrepancies in this trend have been linked to the rate of change in the optical absorption coefficient with temperature. The influence of fluence on deposition rate was found to follow a sigmoidal dependence. Surface roughness was observed to have a diametrically opposed trend with pulse delay depending on whether the OH or CH vibrational mode was excited. In the case of CH excitation, we suggest that the rougher films are due to the absorbance of the second pulse by droplets within the plume containing residual solvent which leads to the formation of molecular balloons and hence irregularly shaped features on the substrate.

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.

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...

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...

Films of brookite TiO2 nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO2 gas-sensing layers

Science.gov (United States)

Caricato, A. P.; Buonsanti, R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Taurino, A.; Rella, R.

2011-09-01

Titanium dioxide (TiO2) nanorods in the brookite phase, with average dimensions of 3-4 nm × 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO2) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm2 and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of ˜150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 nanorods and crystalline spherical nanoparticles with an average diameter of ˜13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO2 mixed in dry air were obtained.

Thin films of polymer blends deposited by matrix-assisted pulsed laser evaporation: Effects of blending ratios

International Nuclear Information System (INIS)

Paun, Irina Alexandra; Ion, Valentin; Moldovan, Antoniu; Dinescu, Maria

2011-01-01

In this work, we show successful use of matrix-assisted pulsed laser evaporation (MAPLE) for obtaining thin films of PEG:PLGA blends, in the view of their use for controlled drug delivery. In particular, we investigate the influence of the blending ratios on the characteristics of the films. We show that the roughness of the polymeric films is affected by the ratio of each polymer within the blend. In addition, we perform Fourier transformed infrared spectroscopy (FTIR) measurements and we find that the intensities ratios of the infrared absorption bands of the two polymers are consistent with the blending ratios. Finally, we assess the optical constants of the polymeric films by spectroscopic ellipsometry (SE). We point out that the blending ratios exert an influence on the optical characteristics of the films and we validate the SE results by atomic force microscopy and UV-vis spectrophotometry. In all, we stress that the ratios in which the two polymers are blended have significant impact on the morphology, chemical structure and optical characteristics of the polymeric films deposited by MAPLE.

The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

Science.gov (United States)

Rogers, Kevin; Milnes, John; Gormally, John

1993-02-01

Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

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.

21 CFR 884.6200 - Assisted reproduction laser system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Assisted reproduction laser system. 884.6200... (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction Devices § 884.6200 Assisted reproduction laser system. (a) Identification. The assisted reproduction laser system is a device...

Temperature responsive functional polymeric thin films obtained by matrix assisted pulsed laser evaporation for cells attachment–detachment study

Energy Technology Data Exchange (ETDEWEB)

Rusen, L. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Mitu, B. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering, IFIN HH, Magurele, Bucharest (Romania); Dinescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania)

2014-05-01

Multifunctional thin films used as thermoresponsive substrate for engineering cell sheets represent an important area in tissue engineering. As the morphology and the chemical characteristics of the thin films directly control their interaction with cells, it is important to correlate these characteristics with the biological answer. In this study, thermally sensitive poly(N-isopropylacrylamide), (pNIPAAm) thin films were prepared by matrix assisted pulsed laser evaporation and utilized in L929 cell adhesion and detachment studies. Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used to determine the pNIPAAm thin films chemical and morphological characteristics. The FTIR data demonstrated that the functional groups in the MAPLE-deposited films remained intact for fluences in the range of 200–600 mJ cm{sup −2}. Within this fluence range, the AFM topographical studies showed that the roughness of the coatings was dependent on laser fluence and the obtained surfaces were characterized by a granular aspect. L929 cell viability studies onto the pNIPAAm coatings showed little or no toxic effect for fluences below 600 mJ cm{sup −2}, while for higher fluences, viability was decreased with more than 50%. The adhesion and detachment of the cell was found to be mainly dependent on the film surface morphology.

Rapid Identification of Intact Staphylococcal Bacteriophages Using Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry

Directory of Open Access Journals (Sweden)

Dana Štveráková

2018-04-01

Full Text Available Staphylococcus aureus is a major causative agent of infections associated with hospital environments, where antibiotic-resistant strains have emerged as a significant threat. Phage therapy could offer a safe and effective alternative to antibiotics. Phage preparations should comply with quality and safety requirements; therefore, it is important to develop efficient production control technologies. This study was conducted to develop and evaluate a rapid and reliable method for identifying staphylococcal bacteriophages, based on detecting their specific proteins using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS profiling that is among the suggested methods for meeting the regulations of pharmaceutical authorities. Five different phage purification techniques were tested in combination with two MALDI-TOF MS matrices. Phages, either purified by CsCl density gradient centrifugation or as resuspended phage pellets, yielded mass spectra with the highest information value if ferulic acid was used as the MALDI matrix. Phage tail and capsid proteins yielded the strongest signals whereas the culture conditions had no effect on mass spectral quality. Thirty-seven phages from Myoviridae, Siphoviridae or Podoviridae families were analysed, including 23 siphophages belonging to the International Typing Set for human strains of S. aureus, as well as phages in preparations produced by Microgen, Bohemia Pharmaceuticals and MB Pharma. The data obtained demonstrate that MALDI-TOF MS can be used to effectively distinguish between Staphylococcus-specific bacteriophages.

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.

Fast screening of short-chain chlorinated paraffins in indoor dust samples by graphene-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Huang, Xiu; Liu, Qian; Gao, Wei; Wang, Yawei; Nie, Zhou; Yao, Shouzhuo; Jiang, Guibin

2018-03-01

As an important class of emerging chemical contaminants, short-chain chlorinated paraffins (SCCPs) are considered as one of the most challenging groups of compounds to analyze. In this paper, we report a new method for fast screening of SCCPs based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with graphene as a matrix and 2,5,6,9-tetrachlorodecane as an internal standard. We found that the use of graphene as MALDI matrix generated high peak intensities for SCCPs while producing few background noises. The ion fragmentation mechanisms of SCCPs in MALDI are discussed in detail. Under the optimized conditions, much lower detection limits of SCCP congeners (0.1-5ng/mL) than those reported previously were obtained. Other distinct advantages such as short analysis time and simplified sample preparation procedures are also demonstrated. The method was successfully applied in fast screening of SCCPs in indoor dust samples and monitoring of human exposure levels to SCCPs, and the results were verified by gas chromatography coupled to negative chemical ionization quadrupole time-of-flight high-resolution mass spectrometry. This work not only offers a new promising tool for SCCP studies, but also further demonstrates the promise of graphene as a new generation of MALDI matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

An in-house assay is superior to Sepsityper for direct matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry identification of yeast species in blood cultures.

Science.gov (United States)

Bidart, Marie; Bonnet, Isabelle; Hennebique, Aurélie; Kherraf, Zine Eddine; Pelloux, Hervé; Berger, François; Cornet, Muriel; Bailly, Sébastien; Maubon, Danièle

2015-05-01

We developed an in-house assay for the direct identification, by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, of yeasts in blood culture. Sixty-one representative strains from 12 species were analyzed in spiked blood cultures. Our assay accurately identified 95 of 107 (88.8%) positive blood cultures and outperformed the commercial Sepsityper kit (81.7% identification). Copyright © 2015, American Society for Microbiology. All Rights Reserved.

MoS_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

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 samples.

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.

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.

Matrix-assisted peptide synthesis on nanoparticles.

Science.gov (United States)

Khandadash, Raz; Machtey, Victoria; Weiss, Aryeh; Byk, Gerardo

2014-09-01

We report a new method for multistep peptide synthesis on polymeric nanoparticles of differing sizes. Polymeric nanoparticles were functionalized via their temporary embedment into a magnetic inorganic matrix that allows multistep peptide synthesis. The matrix is removed at the end of the process for obtaining nanoparticles functionalized with peptides. The matrix-assisted synthesis on nanoparticles was proved by generating various biologically relevant peptides. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite.

Science.gov (United States)

Omrani, Ladan Ranjbar; Farjadfar, Shayan; Pedram, Parham; Sadray, Sima; Kamangar, Sedighe Sadat Hashemi; Chiniforoush, Nasim

2017-06-30

Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

Dispensing pico to nanolitre of a natural hydrogel by laser-assisted bioprinting

Directory of Open Access Journals (Sweden)

Deiwick Andrea

2011-03-01

Full Text Available Abstract Background Laser-assisted bioprinting of multi-cellular replicates in accordance with CAD blueprint may substantially improve our understandings of fundamental aspects of 3 D cell-cell and cell-matrix interactions in vitro. For predictable printing results, a profound knowledge about effects of different processing parameters is essential for realisation of 3 D cell models with well-defined cell densities. Methods Time-resolved imaging of the hydrogel jet dynamics and quantitative assessment of the dependence of printed droplet diameter on the process characteristics were conducted. Results The existence of a counterjet was visualised, proving the bubble collapsing theory for the jet formation. Furthermore, by adjusting the viscosity and height of the applied hydrogel layer in combination with different laser pulse energies, the printing of volumes in the range of 10 to 7000 picolitres was demonstrated. Additionally, the relationship between the viscosity and the layer thickness at different laser pulse energies on the printed droplet volume was identified. Conclusions These findings are essential for the advancement of laser-assisted bioprinting by enabling predictable printing results and the integration of computational methods in the generation of 3 D multi-cellular constructs.

Respiratory complications after diode-laser-assisted tonsillotomy.

Science.gov (United States)

Fischer, Miloš; Horn, Iris-Susanne; Quante, Mirja; Merkenschlager, Andreas; Schnoor, Jörg; Kaisers, Udo X; Dietz, Andreas; Kluba, Karsten

2014-08-01

Children with certain risk factors, such as comorbidities or severe obstructive sleep apnea syndrome (OSAS) are known to require extended postoperative monitoring after adenotonsillectomy. However, there are no recommendations available for diode-laser-assisted tonsillotomy. A retrospective chart review of 96 children who underwent diode-laser-assisted tonsillotomy (07/2011-06/2013) was performed. Data for general and sleep apnea history, power of the applied diode-laser (λ = 940 nm), anesthesia parameters, the presence of postoperative respiratory complications and postoperative healing were evaluated. After initially uncomplicated diode-laser-assisted tonsillotomy, an adjustment of post-anesthesia care was necessary in 16 of 96 patients due to respiratory failure. Respiratory complications were more frequent in younger children (3.1 vs. 4.0 years, p = 0.049, 95 % CI -1.7952 to -0.0048) and in children who suffered from nocturnal apneas (OR = 5.00, p diode-laser power higher than 13 W could be identified as a risk factor for the occurrence of a postoperative oropharyngeal edema (OR = 3.45, p diode-laser-assisted tonsillotomy. We recommend a reduced diode-laser power (<13 W) to reduce oropharyngeal edema.

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.

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

Science.gov (United States)

Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

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.

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

Rapid identification of pathogens directly from blood culture bottles by Bruker matrix-assisted laser desorption laser ionization-time of flight mass spectrometry versus routine methods.

Science.gov (United States)

Jamal, Wafaa; Saleem, Rola; Rotimi, Vincent O

2013-08-01

The use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of microorganisms directly from blood culture is an exciting dimension to the microbiologists. We evaluated the performance of Bruker SepsiTyper kit™ (STK) for direct identification of bacteria from positive blood culture. This was done in parallel with conventional methods. Nonrepetitive positive blood cultures from 160 consecutive patients were prospectively evaluated by both methods. Of 160 positive blood cultures, the STK identified 114 (75.6%) isolates and routine conventional method 150 (93%). Thirty-six isolates were misidentified or not identified by the kit. Of these, 5 had score of >2.000 and 31 had an unreliable low score of <1.7. Four of 8 yeasts were identified correctly. The average turnaround time using the STK was 35 min, including extraction steps and 30:12 to 36:12 h with routine method. The STK holds promise for timely management of bacteremic patients. Copyright © 2013 Elsevier Inc. All rights reserved.

Corona discharge secondary ionization of laser desorbed neutral molecules from a liquid matrix at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Turney, Kevin [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States); Harrison, W.W. [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States)]. E-mail: harrison@chem.ufl.edu

2006-06-15

Matrix assisted laser desorption/ionization (MALDI) is studied at atmospheric pressure using liquid sampling methods. A time-of-flight mass spectrometer couples to an open sample stage accessed by a UV laser for desorption and ionization. Also coupled to the sampling state is a corona discharge for auxiliary ionization of desorbed neutral molecules. The interaction of the laser desorption and corona ionization is studied for a range of desorption conditions, showing enhanced analyte ionization, but the effect is analytically advantageous only at low desorption rates. The effect of corona discharge voltage was also explored. The decoupling of neutral molecule formation and subsequent ionization provides an opportunity to study each process separately.

Corona discharge secondary ionization of laser desorbed neutral molecules from a liquid matrix at atmospheric pressure

International Nuclear Information System (INIS)

Turney, Kevin; Harrison, W.W.

2006-01-01

Matrix assisted laser desorption/ionization (MALDI) is studied at atmospheric pressure using liquid sampling methods. A time-of-flight mass spectrometer couples to an open sample stage accessed by a UV laser for desorption and ionization. Also coupled to the sampling state is a corona discharge for auxiliary ionization of desorbed neutral molecules. The interaction of the laser desorption and corona ionization is studied for a range of desorption conditions, showing enhanced analyte ionization, but the effect is analytically advantageous only at low desorption rates. The effect of corona discharge voltage was also explored. The decoupling of neutral molecule formation and subsequent ionization provides an opportunity to study each process separately

On plate graphite supported sample processing for simultaneous lipid and protein identification by matrix assisted laser desorption ionization mass spectrometry.

Science.gov (United States)

Calvano, Cosima Damiana; van der Werf, Inez Dorothé; Sabbatini, Luigia; Palmisano, Francesco

2015-05-01

The simultaneous identification of lipids and proteins by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) after direct on-plate processing of micro-samples supported on colloidal graphite is demonstrated. Taking advantages of large surface area and thermal conductivity, graphite provided an ideal substrate for on-plate proteolysis and lipid extraction. Indeed proteins could be efficiently digested on-plate within 15 min, providing sequence coverages comparable to those obtained by conventional in-solution overnight digestion. Interestingly, detection of hydrophilic phosphorylated peptides could be easily achieved without any further enrichment step. Furthermore, lipids could be simultaneously extracted/identified without any additional treatment/processing step as demonstrated for model complex samples such as milk and egg. The present approach is simple, efficient, of large applicability and offers great promise for protein and lipid identification in very small samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry in Clinical Microbiology: What Are the Current Issues?

Science.gov (United States)

van Belkum, Alex; Welker, Martin; Pincus, David; Charrier, Jean Philippe; Girard, Victoria

2017-11-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized the identification of microbial species in clinical microbiology laboratories. MALDI-TOF-MS has swiftly become the new gold-standard method owing to its key advantages of simplicity and robustness. However, as with all new methods, adoption of the MALDI-TOF MS approach is still not widespread. Optimal sample preparation has not yet been achieved for several applications, and there are continuing discussions on the need for improved database quality and the inclusion of additional microbial species. New applications such as in the field of antimicrobial susceptibility testing have been proposed but not yet translated to the level of ease and reproducibility that one should expect in routine diagnostic systems. Finally, during routine identification testing, unexpected results are regularly obtained, and the best methods for transmitting these results into clinical care are still evolving. We here discuss the success of MALDI-TOF MS in clinical microbiology and highlight fields of application that are still amenable to improvement. © The Korean Society for Laboratory Medicine.

Peptidylation for the determination of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Tang, Feng; Cen, Si-Ying; He, Huan; Liu, Yi; Yuan, Bi-Feng; Feng, Yu-Qi

2016-05-23

Determination of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been a great challenge in the analytical research field. Here we developed a universal peptide-based derivatization (peptidylation) strategy for the sensitive analysis of low-molecular-weight compounds by MALDI-TOF-MS. Upon peptidylation, the molecular weights of target analytes increase, thus avoiding serious matrix ion interference in the low-molecular-weight region in MALDI-TOF-MS. Since peptides typically exhibit good signal response during MALDI-TOF-MS analysis, peptidylation endows high detection sensitivities of low-molecular-weight analytes. As a proof-of-concept, we analyzed low-molecular-weight compounds of aldehydes and thiols by the developed peptidylation strategy. Our results showed that aldehydes and thiols can be readily determined upon peptidylation, thus realizing the sensitive and efficient determination of low-molecular-weight compounds by MALDI-TOF-MS. Moreover, target analytes also can be unambiguously detected in biological samples using the peptidylation strategy. The established peptidylation strategy is a universal strategy and can be extended to the sensitive analysis of various low-molecular-weight compounds by MALDI-TOF-MS, which may be potentially used in areas such as metabolomics.

Evaluation of matrix-assisted laser desorption/ionization time of flight mass spectrometry for the identification of ceratopogonid and culicid larvae.

Science.gov (United States)

Steinmann, I C; Pflüger, V; Schaffner, F; Mathis, A; Kaufmann, C

2013-03-01

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the rapid identification of ceratopogonid larvae. Optimal sample preparation as evaluated with laboratory-reared biting midges Culicoides nubeculosus was the homogenization of gut-less larvae in 10% formic acid, and analysis of 0.2 mg/ml crude protein homogenate mixed with SA matrix at a ratio of 1:1.5. Using 5 larvae each of 4 ceratopogonid species (C. nubeculosus, C. obsoletus, C. decor, and Dasyhelea sp.) and of 2 culicid species (Aedes aegypti, Ae. japonicus), biomarker mass sets between 27 and 33 masses were determined. In a validation study, 67 larvae belonging to the target species were correctly identified by automated database-based identification (91%) or manual full comparison (9%). Four specimens of non-target species did not yield identification. As anticipated for holometabolous insects, the biomarker mass sets of adults cannot be used for the identification of larvae, and vice versa, because they share only very few similar masses as shown for C. nubeculosus, C. obsoletus, and Ae. japonicus. Thus, protein profiling by MALDI-TOF as a quick, inexpensive and accurate alternative tool is applicable to identify insect larvae of vector species collected in the field.

Detection of lung cancer using plasma protein profiling by matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Shevchenko, Valeriy E; Arnotskaya, Natalia E; Zaridze, David G

2010-01-01

There are no satisfactory plasma biomarkers which are available for the early detection and monitoring of lung cancer, one of the most frequent cancers worldwide. The aim of this study is to explore the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) to plasma proteomic patterns to distinguish lung cancer patients from healthy individuals. The EDTA plasma samples have been pre-fractionated using magnetic bead kits functionalized with weak cation exchange coatings. We compiled MS protein profiles for 90 patients with squamous cell carcinomas (SCC) and compared them with profiles from 187 healthy controls. The MALDI-ToF spectra were analyzed statistically using ClinProTools bioinformatics software. Depending on the sample used, up to 441 peaks/spectrum could be detected in a mass range of 1000-20,000 Da; 33 of these proteins had statistically differential expression levels between SCC and control plasma (P 90%) in external validation test. These results suggest that plasma MALDI-ToF MS protein profiling can distinguish patients with SCC and also from healthy individuals with relatively high sensitivity and specificity and that MALDI- ToF MS is a potential tool for the screening of lung cancer.

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.

Films of brookite TiO{sub 2} nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO{sub 2} gas-sensing layers

Energy Technology Data Exchange (ETDEWEB)

Caricato, A.P.; Cesaria, M.; Luches, A.; Martino, M. [University of Salento, Department of Physics, Lecce (Italy); Buonsanti, R. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); Catalano, M.; Manera, M.G.; Taurino, A.; Rella, R. [IMM-CNR, Institute for Microelectronics and Microsystems, Lecce (Italy); Cozzoli, P.D. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); University of Salento, Department of Innovation Engineering, Lecce (Italy)

2011-09-15

Titanium dioxide (TiO{sub 2}) nanorods in the brookite phase, with average dimensions of 3-4 nm x 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO{sub 2}) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm{sup 2} and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of {proportional_to}150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO{sub 2} nanorods and crystalline spherical nanoparticles with an average diameter of {proportional_to}13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO{sub 2} mixed in dry air were obtained. (orig.)

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.

Fast and reliable diagnosis of XDR Acinetobacter baumannii meningitis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Brunetti, Grazia; Ceccarelli, Giancarlo; Giordano, Alessandra; Navazio, Anna Sara; Vittozzi, Pietro; Venditti, Mario; Raponi, Giammarco

2018-01-01

Bacterial meningitis is a medical emergency needing quick and timely diagnosis. Even though meningitis caused by Acinetobacter baumannii is relatively rare, it is associated with high mortality rates especially in neurosurgery patients and represents a serious therapeutic problem due to the limited penetration of effective antibiotics into the cerebrospinal fluid. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) has been effectively used as a rapid method for microbial identification. In this case report we identified A. baumanni by MALDI-TOF technique directly from the CSF drawn from the external ventricular drainage of a patient with severe confusional state and signs of meningism. Simultaneously the antibiotic susceptibility test was performed by automated method from the pellet of the broth-enriched sample. The MALDI-TOF technique allowed microbial identification in less than 30 minutes, and the susceptibility test result was available in eight hours, thus allowing a fast diagnosis ready for prompt and targeted antimicrobial therapy.

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...... the Sepsityper™ Kit (Bruker Daltonics) with Biotyper 2.0 software could be used as a fast diagnostic tool for bacteria and fungi and whether a 1.5 cut-off score could improve species identification compared with the recommended score of 1.8. Two hundred and fifty-six positive blood vials from 210 patients and 19...

Rapid identification of bacteria in positive blood culture broths by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Stevenson, Lindsay G; Drake, Steven K; Murray, Patrick R

2010-02-01

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a rapid, accurate method for identifying bacteria and fungi recovered on agar culture media. We report herein a method for the direct identification of bacteria in positive blood culture broths by MALDI-TOF mass spectrometry. A total of 212 positive cultures were examined, representing 32 genera and 60 species or groups. The identification of bacterial isolates by MALDI-TOF mass spectrometry was compared with biochemical testing, and discrepancies were resolved by gene sequencing. No identification (spectral score of blood culture broth. Of the bacteria with a spectral score of > or = 1.7, 162 (95.3%) of 170 isolates were correctly identified. All 8 isolates of Streptococcus mitis were misidentified as being Streptococcus pneumoniae isolates. This method provides a rapid, accurate, definitive identification of bacteria within 1 h of detection in positive blood cultures with the caveat that the identification of S. pneumoniae would have to be confirmed by an alternative test.

Plasma wave detection in laser spectroscopy and gas chromatography

International Nuclear Information System (INIS)

Franzke, J.; Irmer, A. von; Veza, D.; Niemax, K.

1995-01-01

Frequency changes of plasma oscillations in low-pressure discharges are used for sensitive detection of atomic or molecular trace gases. Analyte selectivity can be either obtained by resonant laser excitation or by gas chromatography

Simultaneous determination of phenolic compounds in Equisetum palustre L. by ultra high performance liquid chromatography with tandem mass spectrometry combined with matrix solid-phase dispersion extraction.

Science.gov (United States)

Wei, Zuofu; Pan, Youzhi; Li, Lu; Huang, Yuyang; Qi, Xiaolin; Luo, Meng; Zu, Yuangang; Fu, Yujie

2014-11-01

A method based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with tandem mass spectrometry is presented for the extraction and determination of phenolic compounds in Equisetum palustre. This method combines the high efficiency of matrix solid-phase dispersion extraction and the rapidity, sensitivity, and accuracy of ultra high performance liquid chromatography with tandem mass spectrometry. The influential parameters of the matrix solid-phase dispersion extraction were investigated and optimized. The optimized conditions were as follows: silica gel was selected as dispersing sorbent, the ratio of silica gel to sample was selected to be 2:1 (400/200 mg), and 8 mL of 80% methanol was used as elution solvent. Furthermore, a fast and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the determination of nine phenolic compounds in E. palustre. This method was carried out within <6 min, and exhibited satisfactory linearity, precision, and recovery. Compared with ultrasound-assisted extraction, the proposed matrix solid-phase dispersion procedure possessed higher extraction efficiency, and was more convenient and time saving with reduced requirements on sample and solvent amounts. All these results suggest that the developed method represents an excellent alternative for the extraction and determination of active components in plant matrices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prospective study on laser-assisted laparascopic partial nephrectomy

Science.gov (United States)

Sroka, Ronald; Hennig, Georg; Zilinberg, Katja; Khoder, Wael Y.

2012-02-01

Introduction: Developments in laparoscopic partial nephrectomy (LPN) opened a demand for surgical tools compatible with laparoscopic manipulations to make laser assisted technique safe, feasible and reproducible. Warm ischemia and bleeding during laparoscopic partial nephrectomy place technical constraints on surgeons. Therefore it was the aim to develop a safe and effective laser assisted partial nephrectomy technique without need for ischemia. Patients and methods: A diode laser emitting light at 1318nm in cw mode was coupled into a bare fibre (core diameter 600 μm) thus able to transfer up to 100W to the tissue. After dry lab experience, a total of 10 patients suffering from kidney malformations underwent laparoscopic/retroperitoneoscopic partial nephrectomy. Clinically, postoperative renal function and serum c-reactive protein (CRP) were monitored. Laser induced coagulation depth and effects on resection margins were evaluated. Demographic, clinical and follow-up data are presented. Using a commercial available fibre guidance instrument for lanringeal intervention, the demands on an innovative laser fibre guidance instrument for the laser assisted laparoscopic partial nephrectomy (LLPN) are summarized. Results: Overall, all laparascopic intervention were succesfull and could be performed without conversion to open surgery. Mean operative time and mean blood loss were comparable to conventional open and laparascopic approaches. Laser assisted resection of the kidney tissue took max 15min. After extirpation of the tumours all patients showed clinical favourable outcome during follow up period. Tumour sizes were measured to be up 5cm in diameter. The depth of the coagulation on the removed tissue ranged between laser assisted coagulated after removal. The sealing of the surface was induced by a slightly larger coagulation margin, but could not measured so far. Based on this experiences a simple and easy to use instrument described serving also for suction and

Identification of Candida species isolated from vulvovaginitis using matrix assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Alizadeh, Majid; Kolecka, Anna; Boekhout, Teun; Zarrinfar, Hossein; Ghanbari Nahzag, Mohamad A; Badiee, Parisa; Rezaei-Matehkolaei, Ali; Fata, Abdolmajid; Dolatabadi, Somayeh; Najafzadeh, Mohammad J

2017-12-01

Vulvovaginal candidiasis (VVC) is a common problem in women. The purpose of this study was to identify Candida isolates by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) from women with vulvovaginitis that were referred to Ghaem Hospital, Mashhad, Iran. This study was conducted on 65 clinical samples isolated from women that were referred to Ghaem Hospital. All specimens were identified using phenotyping techniques, such as microscopy and culture on Sabouraud dextrose agar and corn meal agar. In addition, all isolates were processed for MALDI-TOF MS identification. Out of the 65 analyzed isolates, 61 (94%) samples were recognized by MALDI-TOF MS. However, the remaining four isolates (6%) had no reliable identification. According to the results, C. albicans (58.5%) was the most frequently isolated species, followed by C. tropicalis (16.9%), C. glabrata (7.7%), C. parapsilosis (7.7%), and guilliermondii (3.1%). As the findings indicated, MALDI TOF MS was successful in the identification of clinical Candida species. C. albicans was identified as the most common Candida species isolated from the women with VVC. Moreover, C. tropicalis was the most common species among the non- albicans Candida species.

Using solvent-free sample preparation to promote protonation of poly(ethylene oxide)s with labile end-groups in matrix-assisted laser desorption/ionisation.

Science.gov (United States)

Mazarin, Michael; Phan, Trang N T; Charles, Laurence

2008-12-01

Protonation is usually required to observe intact ions during matrix-assisted laser desorption/ionization (MALDI) of polymers containing fragile end-groups while cation adduction induces chain-end degradation. These polymers, generally obtained via living free radical polymerization techniques, are terminated with a functionality in which a bond is prone to homolytic cleavage, as required by the polymerization process. A solvent-free sample preparation method was used here to avoid salt contaminant from the solvent traditionally used in the dried-droplet MALDI procedure. Solvent-based and solvent-free sample preparations were compared for a series of three poly(ethylene oxide) polymers functionalized with a labile end-group in a nitroxide-mediated polymerization reaction, using 2,4,6-trihydroxyacetophenone (THAP) as the matrix without any added salt. Intact oligomer ions could only be produced as protonated molecules in solvent-free MALDI while sodium adducts of degraded polymers were formed from the dried-droplet samples. Although MALDI analysis was performed at the laser threshold, fragmentation of protonated macromolecules was still observed to occur. However, in contrast to sodiated molecules, dissociation of protonated oligomers does not involve the labile C--ON bond of the end-group. As the macromolecule size increased, protonation appeared to be less efficient and sodium adduction became the dominant ionization process, although no sodium salt was added in the preparation. Formation of sodiated degraded macromolecules would be dictated by increasing cation affinity as the size of the oligomers increases and would reveal the presence of salts at trace levels in the MALDI samples.

Assisting Gas Optimization in CO2 Laser Welding

DEFF Research Database (Denmark)

Gong, Hui; Olsen, Flemming Ove

1996-01-01

High quality laser welding is achieved under the condition of optimizing all process parameters. Assisting gas plays an important role for sound welds. In the conventional welding process assisting gas is used as a shielding gas to prevent that the weld seam oxidates. In the laser welding process...... assisting gas is also needed to control the laser induced plasma.Assisting gas is one of the most important parameters in the laser welding process. It is responsible for obtaining a quality weld which is characterized by deep penetration, no interior imperfections, i.e. porosity, no crack, homogeneous seam...... surface, etc. In this work a specially designed flexible off-axis nozzle capable of adjusting the angle of the nozzle, the diameter of the nozzle, and the distance between the nozzle end and the welding zone is tested. In addition to the nozzle parameters three gases, Nitrogen, Argon, and Helium...

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

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.

ADAM 12 cleaves extracellular matrix proteins and correlates with cancer status and stage

DEFF Research Database (Denmark)

Roy, Roopali; Wewer, Ulla M; Zurakowski, David

2004-01-01

-Sepharose affinity chromatography followed by protein identification by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Four peptides were identified that spanned the amino acid sequence of ADAM 12. Immunoblot analysis using ADAM 12-specific antibodies detected an approximately 68-k......Da band identified as the mature form of ADAM 12. To characterize catalytic properties of ADAM 12, full-length ADAM 12-S was expressed in COS-7 cells and purified. Substrate specificity studies demonstrated that ADAM 12-S degrades gelatin, type IV collagen, and fibronectin but not type I collagen...... or casein. Gelatinase activity of ADAM 12 was completely abrogated by zinc chelators 1,10-phenanthroline and EDTA and was partially inhibited by the hydroxamate inhibitor Marimastat. Endogenous matrix metalloprotease inhibitor TIMP-3 inhibited activity. To validate our initial identification of this enzyme...

Proteome-based bacterial identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS): A revolutionary shift in clinical diagnostic microbiology.

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Nomura, Fumio

2015-06-01

Rapid and accurate identification of microorganisms, a prerequisite for appropriate patient care and infection control, is a critical function of any clinical microbiology laboratory. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a quick and reliable method for identification of microorganisms, including bacteria, yeast, molds, and mycobacteria. Indeed, there has been a revolutionary shift in clinical diagnostic microbiology. In the present review, the state of the art and advantages of MALDI-TOF MS-based bacterial identification are described. The potential of this innovative technology for use in strain typing and detection of antibiotic resistance is also discussed. This article is part of a Special Issue entitled: Medical Proteomics. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification of Blood Culture Isolates Directly from Positive Blood Cultures by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and a Commercial Extraction System: Analysis of Performance, Cost, and Turnaround Time

OpenAIRE

Lagacé-Wiens, Philippe R. S.; Adam, Heather J.; Karlowsky, James A.; Nichol, Kimberly A.; Pang, Paulette F.; Guenther, Jodi; Webb, Amanda A.; Miller, Crystal; Alfa, Michelle J.

2012-01-01

Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry represents a revolution in the rapid identification of bacterial and fungal pathogens in the clinical microbiology laboratory. Recently, MALDI-TOF has been applied directly to positive blood culture bottles for the rapid identification of pathogens, leading to reductions in turnaround time and potentially beneficial patient impacts. The development of a commercially available extraction kit (Bruker Sepsit...

Dye-enhanced protein solders and patches in laser-assisted tissue welding.

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Small, W; Heredia, N J; Maitland, D J; Da Silva, L B; Matthews, D L

1997-01-01

This study examines the use of dye-enhanced protein bonding agents in 805 nm diode laser-assisted tissue welding. A comparison of an albumin liquid solder and collagen solid-matrix patches used to repair arteriotomies in an in vitro porcine model is presented. Extrinsic bonding media in the form of solders and patches have been used to enhance the practice of laser tissue welding. Preferential absorption of the laser wavelength has been achieved by the incorporation of chromophores. Both the solder and the patch included indocyanine green dye (ICG) to absorb the 805 nm continuous-wave diode laser light used to perform the welds. Solder-mediated welds were divided into two groups (high power/short exposure and low power/long exposure), and the patches were divided into three thickness groups ranging from 0.1 to 1.3 mm. The power used to activate the patches was constant, but the exposure time was increased with patch thickness. Burst pressure results indicated that solder-mediated and patched welds yielded similar average burst strengths in most cases, but the patches provided a higher success rate (i.e., more often exceeded 150 mmHg) and were more consistent (i.e., smaller standard deviation) than the solder. The strongest welds were obtained using 1.0-1.3 mm thick patches, while the high power/short exposure solder group was the weakest. Though the solder and patches yielded similar acute weld strengths, the solid-matrix patches facilitated the welding process and provided consistently strong welds. The material properties of the extrinsic agents influenced their performance.

A peptidomic approach for monitoring and characterising peptide cyanotoxins produced in Italian lakes by matrix-assisted laser desorption/ionisation and quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Ferranti, Pasquale; Nasi, Antonella; Bruno, Milena; Basile, Adriana; Serpe, Luigi; Gallo, Pasquale

2011-05-15

In recent years, the occurrence of cyanobacterial blooms in eutrophic freshwaters has been described all over the world, including most European countries. Blooms of cyanobacteria may produce mixtures of toxic secondary metabolites, called cyanotoxins. Among these, the most studied are microcystins, a group of cyclic heptapeptides, because of their potent hepatotoxicity and activity as tumour promoters. Other peptide cyanotoxins have been described whose structure and toxicity have not been thoroughly studied. Herein we present a peptidomic approach aimed to characterise and quantify the peptide cyanotoxins produced in two Italian lakes, Averno and Albano. The procedure was based on matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry mass spectrometry (MALDI-TOF-MS) analysis for rapid detection and profiling of the peptide mixture complexity, combined with liquid chromatography/electrospray ionisation quadrupole time-of- flight tandem mass spectrometry (LC/ESI-Q-TOF-MS/MS) which provided unambiguous structural identification of the main compounds, as well as accurate quantitative analysis of microcystins. In the case of Lake Averno, a novel variant of microcystin-RR and two novel anabaenopeptin variants (Anabaenopeptins B(1) and Anabaenopeptin F(1)), presenting homoarginine in place of the commonly found arginine, were detected and characterised. In Lake Albano, the peculiar peptide patterns in different years were compared, as an example of the potentiality of the peptidomic approach for fast screening analysis, prior to fine structural analysis and determination of cyanotoxins, which included six novel aeruginosin variants. This approach allows for wide range monitoring of cyanobacteria blooms, and to collect data for evaluating possible health risks to consumers, through the panel of the compounds produced along different years. Copyright © 2011 John Wiley & Sons, Ltd.

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

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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.

Laser assisted hybrid additive manufacturing of thermoelectric modules

Science.gov (United States)

Zhang, Tao; Tewolde, Mahder; Longtin, Jon P.; Hwang, David J.

2017-02-01

Thermoelectric generators (TEGs) are an attractive means to produce electricity, particular from waste heat applications. However, TEGs are almost exclusively manufactured as flat, rigid modules of limited size and shape, and therefore an appropriate mounting for intimate contact of TEGs modules onto arbitrary surfaces represents a significant challenge. In this study, we introduce laser assisted additive manufacturing method to produce multi-layered thermoelectric generator device directly on flat and non-flat surfaces for waste heat recovery. The laser assisted processing spans from laser scribing of thermal sprayed thin films, curing of dispensed thermoelectric inks and selective laser sintering to functionalize thermoelectric materials.

Rapid Quantification of 25-Hydroxyvitamin D3 in Human Serum by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

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Qi, Yulin; Müller, Miriam; Stokes, Caroline S.; Volmer, Dietrich A.

2018-04-01

LC-MS/MS is widely utilized today for quantification of vitamin D in biological fluids. Mass spectrometric assays for vitamin D require very careful method optimization for precise and interference-free, accurate analyses however. Here, we explore chemical derivatization and matrix-assisted laser desorption/ionization (MALDI) as a rapid alternative for quantitative measurement of 25-hydroxyvitamin D3 in human serum, and compare it to results from LC-MS/MS. The method implemented an automated imaging step of each MALDI spot, to locate areas of high intensity, avoid sweet spot phenomena, and thus improve precision. There was no statistically significant difference in vitamin D quantification between the MALDI-MS/MS and LC-MS/MS: mean ± standard deviation for MALDI-MS—29.4 ± 10.3 ng/mL—versus LC-MS/MS—30.3 ± 11.2 ng/mL (P = 0.128)—for the sum of the 25-hydroxyvitamin D epimers. The MALDI-based assay avoided time-consuming chromatographic separation steps and was thus much faster than the LC-MS/MS assay. It also consumed less sample, required no organic solvents, and was readily automated. In this proof-of-concept study, MALDI-MS readily demonstrated its potential for mass spectrometric quantification of vitamin D compounds in biological fluids.

Direct matrix-assisted laser desorption ionization time-of-flight mass spectrometry improves appropriateness of antibiotic treatment of bacteremia.

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Anne L M Vlek

Full Text Available Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS allows the identification of microorganisms directly from positive blood culture broths. Use of the MALDI-TOF MS for rapid identification of microorganisms from blood culture broths can reduce the turnaround time to identification and may lead to earlier appropriate treatment of bacteremia. During February and April 2010, direct MALDI-TOF MS was routinely performed on all positive blood cultures. During December 2009 and March 2010 no direct MALDI-TOF MS was used. Information on antibiotic therapy was collected from the hospital and intensive care units' information systems from all positive blood cultures during the study period. In total, 253 episodes of bacteremia were included of which 89 during the intervention period and 164 during the control period. Direct performance of MALDI-TOF MS on positive blood culture broths reduced the time till species identification by 28.8-h and was associated with an 11.3% increase in the proportion of patients receiving appropriate antibiotic treatment 24 hours after blood culture positivity (64.0% in the control period versus 75.3% in the intervention period (p0.01. Routine implementation of this technique increased the proportion of patients on adequate antimicrobial treatment within 24 hours.

Direct matrix-assisted laser desorption ionization time-of-flight mass spectrometry improves appropriateness of antibiotic treatment of bacteremia.

Science.gov (United States)

Vlek, Anne L M; Bonten, Marc J M; Boel, C H Edwin

2012-01-01

Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows the identification of microorganisms directly from positive blood culture broths. Use of the MALDI-TOF MS for rapid identification of microorganisms from blood culture broths can reduce the turnaround time to identification and may lead to earlier appropriate treatment of bacteremia. During February and April 2010, direct MALDI-TOF MS was routinely performed on all positive blood cultures. During December 2009 and March 2010 no direct MALDI-TOF MS was used. Information on antibiotic therapy was collected from the hospital and intensive care units' information systems from all positive blood cultures during the study period. In total, 253 episodes of bacteremia were included of which 89 during the intervention period and 164 during the control period. Direct performance of MALDI-TOF MS on positive blood culture broths reduced the time till species identification by 28.8-h and was associated with an 11.3% increase in the proportion of patients receiving appropriate antibiotic treatment 24 hours after blood culture positivity (64.0% in the control period versus 75.3% in the intervention period (p0.01)). Routine implementation of this technique increased the proportion of patients on adequate antimicrobial treatment within 24 hours.

Direct identification of bacteria in blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: a new methodological approach.

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Kroumova, Vesselina; Gobbato, Elisa; Basso, Elisa; Mucedola, Luca; Giani, Tommaso; Fortina, Giacomo

2011-08-15

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been demonstrated to be a powerful tool for the rapid identification of bacteria from growing colonies. In order to speed up the identification of bacteria, several authors have evaluated the usefulness of this MALDI-TOF MS technology for the direct and quick identification bacteria from positive blood cultures. The results obtained so far have been encouraging but have also shown some limitations, mainly related to the bacterial growth and to the presence of interference substances belonging to the blood cultures. In this paper, we present a new methodological approach that we have developed to overcome these limitations, based mainly on an enrichment of the sample into a growing medium before the extraction process, prior to mass spectrometric analysis. The proposed method shows important advantages for the identification of bacterial strains, yielding an increased identification score, which gives higher confidence in the results. Copyright © 2011 John Wiley & Sons, Ltd.

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.

MALDI-MS analysis and theoretical evaluation of olanzapine as a UV laser desorption ionization (LDI) matrix.

Science.gov (United States)

Musharraf, Syed Ghulam; Ameer, Mariam; Ali, Arslan

2017-01-05

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) being soft ionization technique, has become a method of choice for high-throughput analysis of proteins and peptides. In this study, we have explored the potential of atypical anti-psychotic drug olanzapine (OLZ) as a matrix for MALDI-MS analysis of peptides aided with the theoretical studies. Seven small peptides were employed as target analytes to check performance of olanzapine and compared with conventional MALDI matrix α-cyano-4-hydroxycinnamic acid (HCCA). All peptides were successfully detected when olanzapine was used as a matrix. Moreover, peptides angiotensin Ι and angiotensin ΙΙ were detected with better S/N ratio and resolution with this method as compared to their analysis by HCCA. Computational studies were performed to determine the thermochemical properties of olanzapine in order to further evaluate its similarity to MALDI matrices which were found in good agreement with the data of existing MALDI matrices. Copyright © 2016. Published by Elsevier B.V.

Identification of Enterobacteriaceae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using the VITEK MS system.

Science.gov (United States)

Richter, S S; Sercia, L; Branda, J A; Burnham, C-A D; Bythrow, M; Ferraro, M J; Garner, O B; Ginocchio, C C; Jennemann, R; Lewinski, M A; Manji, R; Mochon, A B; Rychert, J A; Westblade, L F; Procop, G W

2013-12-01

This multicenter study evaluated the accuracy of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry identifications from the VITEK MS system (bioMérieux, Marcy l'Etoile, France) for Enterobacteriaceae typically encountered in the clinical laboratory. Enterobacteriaceae isolates (n = 965) representing 17 genera and 40 species were analyzed on the VITEK MS system (database v2.0), in accordance with the manufacturer's instructions. Colony growth (≤72 h) was applied directly to the target slide. Matrix solution (α-cyano-4-hydroxycinnamic acid) was added and allowed to dry before mass spectrometry analysis. On the basis of the confidence level, the VITEK MS system provided a species, genus only, or no identification for each isolate. The accuracy of the mass spectrometric identification was compared to 16S rRNA gene sequencing performed at MIDI Labs (Newark, DE). Supplemental phenotypic testing was performed at bioMérieux when necessary. The VITEK MS result agreed with the reference method identification for 96.7% of the 965 isolates tested, with 83.8% correct to the species level and 12.8% limited to a genus-level identification. There was no identification for 1.7% of the isolates. The VITEK MS system misidentified 7 isolates (0.7 %) as different genera. Three Pantoea agglomerans isolates were misidentified as Enterobacter spp. and single isolates of Enterobacter cancerogenus, Escherichia hermannii, Hafnia alvei, and Raoultella ornithinolytica were misidentified as Klebsiella oxytoca, Citrobacter koseri, Obesumbacterium proteus, and Enterobacter aerogenes, respectively. Eight isolates (0.8 %) were misidentified as a different species in the correct genus. The VITEK MS system provides reliable mass spectrometric identifications for Enterobacteriaceae.

Specific Cα-C Bond Cleavage of β-Carbon-Centered Radical Peptides Produced by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Science.gov (United States)

Nagoshi, Keishiro; Yamakoshi, Mariko; Sakamoto, Kenya; Takayama, Mitsuo

2018-04-01

Radical-driven dissociation (RDD) of hydrogen-deficient peptide ions [M - H + H]·+ has been examined using matrix-assisted laser dissociation/ionization in-source decay mass spectrometry (MALDI-ISD MS) with the hydrogen-abstracting matrices 4-nitro-1-naphthol (4,1-NNL) and 5-nitrosalicylic acid (5-NSA). The preferential fragment ions observed in the ISD spectra include N-terminal [a] + ions and C-terminal [x]+, [y + 2]+, and [w]+ ions which imply that β-carbon (Cβ)-centered radical peptide ions [M - Hβ + H]·+ are predominantly produced in MALDI conditions. RDD reactions from the peptide ions [M - Hβ + H]·+ successfully explains the fact that both [a]+ and [x]+ ions arising from cleavage at the Cα-C bond of the backbone of Gly-Xxx residues are missing from the ISD spectra. Furthermore, the formation of [a]+ ions originating from the cleavage of Cα-C bond of deuterated Ala(d3)-Xxx residues indicates that the [a]+ ions are produced from the peptide ions [M - Hβ + H]·+ generated by deuteron-abstraction from Ala(d3) residues. It is suggested that from the standpoint of hydrogen abstraction via direct interactions between the nitro group of matrix and hydrogen of peptides, the generation of the peptide radical ions [M - Hβ + H]·+ is more favorable than that of the α-carbon (Cα)-centered radical ions [M - Hα + H]·+ and the amide nitrogen-centered radical ions [M - HN + H]·+, while ab initio calculations indicate that the formation of [M - Hα + H]·+ is energetically most favorable. [Figure not available: see fulltext.

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.

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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

Laser assisted tunneling in a Tonks–Girardeau gas

International Nuclear Information System (INIS)

Lelas, Karlo; Drpić, Nikola; Dubček, Tena; Buljan, Hrvoje; Jukić, Dario; Pezer, Robert

2016-01-01

We investigate the applicability of laser assisted tunneling in a strongly interacting one-dimensional (1D) Bose gas (the Tonks–Girardeau gas) in optical lattices. We find that the stroboscopic dynamics of the Tonks–Girardeau gas in a continuous Wannier–Stark-ladder potential, supplemented with laser assisted tunneling, effectively realizes the ground state of 1D hard-core bosons in a discrete lattice with nontrivial hopping phases. We compare observables that are affected by the interactions, such as the momentum distribution, natural orbitals and their occupancies, in the time-dependent continuous system, to those of the ground state of the discrete system. Stroboscopically, we find an excellent agreement, indicating that laser assisted tunneling is a viable technique for realizing novel ground states and phases with hard-core 1D Bose gases. (paper)

Ion yields in UV-MALDI mass spectrometry as a function of excitation laser wavelength and optical and physico-chemical properties of classical and halogen-substituted MALDI matrixes.

Science.gov (United States)

Soltwisch, Jens; Jaskolla, Thorsten W; Hillenkamp, Franz; Karas, Michael; Dreisewerd, Klaus

2012-08-07

The laser wavelength constitutes a key parameter in ultraviolet-matrix-assisted laser desorption ionization-mass spectrometry (UV-MALDI-MS). Optimal analytical results are only achieved at laser wavelengths that correspond to a high optical absorption of the matrix. In the presented work, the wavelength dependence and the contribution of matrix proton affinity to the MALDI process were investigated. A tunable dye laser was used to examine the wavelength range between 280 and 355 nm. The peptide and matrix ion signals recorded as a function of these irradiation parameters are displayed in the form of heat maps, a data representation that furnishes multidimensional data interpretation. Matrixes with a range of proton affinities from 809 to 866 kJ/mol were investigated. Among those selected are the standard matrixes 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA) as well as five halogen-substituted cinnamic acid derivatives, including the recently introduced 4-chloro-α-cyanocinnamic acid (ClCCA) and α-cyano-2,4-difluorocinnamic acid (DiFCCA) matrixes. With the exception of DHB, the highest analyte ion signals were obtained toward the red side of the peak optical absorption in the solid state. A stronger decline of the molecular analyte ion signals generated from the matrixes was consistently observed at the low wavelength side of the peak absorption. This effect is mainly the result of increased fragmentation of both analyte and matrix ions. Optimal use of multiply halogenated matrixes requires adjustment of the excitation wavelength to values below that of the standard MALDI lasers emitting at 355 (Nd:YAG) or 337 nm (N(2) laser). The combined data provide new insights into the UV-MALDI desorption/ionization processes and indicate ways to improve the analytical sensitivity.

Parameters in fractional laser assisted delivery of topical anesthetics: Role of laser type and laser settings.

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Meesters, Arne A; Nieboer, Marilin J; Kezic, Sanja; de Rie, Menno A; Wolkerstorfer, Albert

2018-05-07

Efficacy of topical anesthetics can be enhanced by pretreatment of the skin with ablative fractional lasers. However, little is known about the role of parameters such as laser modality and laser density settings in this technique. Aims of this study were to compare the efficacy of pretreatment with two different ablative fractional laser modalities, a CO 2 laser and an Er:YAG laser, and to assess the role of laser density in ablative fractional laser assisted topical anesthesia. In each of 15 healthy subjects, four 10 × 10 mm test regions on the back were randomized to pretreatment (70-75 μm ablation depth) with CO 2 laser at 5% density, CO 2 laser at 15% density, Er:YAG laser at 5% density or Er:YAG laser at 15% density. Articaine hydrochloride 40 mg/ml + epinephrine 10 μg/ml solution was applied under occlusion to all four test regions. After 15 minutes, a pass with the CO 2 laser (1,500 μm ablation depth) was administered as pain stimulus to each test region. A reference pain stimulus was given on unanesthetized skin. The main outcome parameter, pain, was scored on a 0-10 visual analogue scale (VAS) after each pain stimulus. Median VAS scores were 1.50 [CO 2 5%], 0.50 [CO 2 15%], 1.50 [Er:YAG 5%], 0.43 [Er:YAG 15%], and 4.50 [unanesthetized reference]. VAS scores for all pretreated test regions were significantly lower compared to the untreated reference region (P laser pretreated regions. However, VAS scores were significantly lower at 15% density compared to 5% density for both for the CO 2 laser (P laser (P laser was considered slightly more painful than pretreatment with Er:YAG laser by the subjects. Fractional laser assisted topical anesthesia is effective even with very low energy settings and an occlusion time of only 15 minutes. Both the CO 2 laser and the Er:YAG laser can be used to assist topical anesthesia although the CO 2 laser pretreatment is experienced as more painful. In our study settings, using articaine

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.

Exploration of polyamide structure-property relationships by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Barrère, Caroline; Rejaibi, Majed; Curat, Aurélien; Hubert-Roux, Marie; Lavanant, Hélène; Afonso, Carlos; Kebir, Nasreddine; Desilles, Nicolas; Lecamp, Laurence; Burel, Fabrice; Loutelier-Bourhis, Corinne

2014-08-15

Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm ). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate. Six different PA copolymers with molecular weights around 3500 g mol(-1) were synthesized with varying proportions of different co-monomers (amino-acid AB/di-amine AA/di-acid BB). Their melting temperature, enthalpy change and crystallinity rate were measured by DSC and X-ray diffraction. Their structural characterization was carried out by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Because of the poor solubility of PA, a solvent-free sample preparation strategy was used with 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix and sodium iodide as the cationizing agent. The different proportions of the repeating unit types led to the formation of PA with melting temperatures ranging from 115°C to 185°C. The structural characterization of these samples by MALDI-TOF-MS revealed a collection of different ion distributions with different sequences of repeating units (AA, BB; AB/AA, BB and AB) in different proportions according to the mixture of monomers used in the synthesis. The relative intensities of these ion distributions were related to sample complexity and structure. They were correlated to DSC and X-ray results, to explain the observed physical properties. The structural information obtained by MALDI-TOF-MS provided a better understanding of the variation of the PA melting temperature and established a structure-properties relationship. This work will allow future PA designs to be monitored. Copyright

Direct identification of bacteria from positive BacT/ALERT blood culture bottles using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry.

Science.gov (United States)

Mestas, Javier; Felsenstein, Susanna; Bard, Jennifer Dien

2014-11-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is a fast and robust method for the identification of bacteria. In this study, we evaluate the performance of a laboratory-developed lysis method (LDT) for the rapid identification of bacteria from positive BacT/ALERT blood culture bottles. Of the 168 positive bottles tested, 159 were monomicrobial, the majority of which were Gram-positive organisms (61.0% versus 39.0%). Using a cut-off score of ≥1.7, 80.4% of the organisms were correctly identified to the species level, and the identification rate of Gram-negative organisms (90.3%) was found to be significantly greater than that of Gram-positive organisms (78.4%). The simplicity and cost-effectiveness of the LDT enable it to be fully integrated into the routine workflow of the clinical microbiology laboratory, allowing for rapid identification of Gram-positive and Gram-negative bacteria within an hour of blood culture positivity. Copyright © 2014 Elsevier Inc. All rights reserved.

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

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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.

Laser Surface Treatment and Modification of Aluminum Alloy Matrix Composites

Science.gov (United States)

Abbass, Muna Khethier

2018-02-01

The present work aimed to study the laser surface treatment and modification of Al-4.0%Cu-1.0%Mg alloy matrix composite reinforced with 10%SiC particles produced by stir casting. The specimens of the base alloy and composite were irradiated with an Nd:YAG laser of 1000 mJ, 1064 nm and 3 Hz . Dry wear test using the pin-on -disc technique at different sliding times (5-30 min) at a constant applied load and sliding speed were performed before and after laser treatment. Micro hardness and wear resistance were increased for all samples after laser hardening treatment. The improvement of these properties is explained by microstructural homogenization and grain refinement of the laser treated surface. Modification and refinement of SiC particles and grain refinement in the microstructure of the aluminum alloy matrix (α-Al) were observed by optical and SEM micrographs. The highest increase in hardness was 21.4% and 26.2% for the base alloy and composite sample respectively.

Microfluidic Isoelectric Focusing of Amyloid Beta Peptides Followed by Micropillar-Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry.

Science.gov (United States)

Mikkonen, Saara; Jacksén, Johan; Roeraade, Johan; Thormann, Wolfgang; Emmer, Åsa

2016-10-18

A novel method for preconcentration and purification of the Alzheimer's disease related amyloid beta (Aβ) peptides by isoelectric focusing (IEF) in 75 nL microchannels combined with their analysis by micropillar-matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) is presented. A semiopen chip-based setup, consisting of open microchannels covered by a lid of a liquid fluorocarbon, was used. IEF was performed in a mixture of four small and chemically well-defined amphoteric carriers, glutamic acid, aspartyl-histidine (Asp-His), cycloserine (cSer), and arginine, which provided a stepwise pH gradient tailored for focusing of the C-terminal Aβ peptides with a pI of 5.3 in the boundary between cSer and Asp-His. Information about the focusing dynamics and location of the foci of Aβ peptides and other compounds was obtained using computer simulation and by performing MALDI-MS analysis directly from the open microchannel. With the established configuration, detection was performed by direct sampling of a nanoliter volume containing the focused Aβ peptides from the microchannel, followed by deposition of this volume onto a chip with micropillar MALDI targets. In addition to purification, IEF preconcentration provides at least a 10-fold increase of the MALDI-MS-signal. After immunoprecipitation and concentration of the eluate in the microchannel, IEF-micropillar-MALDI-MS is demonstrated to be a suitable platform for detection of Aβ peptides in human cerebrospinal fluid as well as in blood plasma.

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.

Laser cladding of wear resistant metal matrix composite coatings

International Nuclear Information System (INIS)

Yakovlev, A.; Bertrand, Ph.; Smurov, I.

2004-01-01

A number of coatings with wear-resistant properties as well as with a low friction coefficient are produced by laser cladding. The structure of these coatings is determined by required performance and realized as metal matrix composite (MMC), where solid lubricant serves as a ductile matrix (e.g. CuSn), reinforced by appropriate ceramic phase (e.g. WC/Co). One of the engineered coating with functionally graded material (FGM) structure has a dry friction coefficient 0.12. Coatings were produced by coaxial injection of powder blend into the zone of laser beam action. Metallographic and tribological examinations were carried out confirming the advanced performance of engineered coatings

Preliminary results of laser-assisted sealing of hand-sewn canine esophageal anastomoses

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Auteri, Joseph S.; Oz, Mehmet C.; Sanchez, Juan A.; Bass, Lawrence S.; Jeevanandam, Valluvan; Williams, Matthew R.; Smith, Craig R.; Treat, Michael R.

1991-07-01

Dehiscence rates of esophageal anastomoses range between 5 and 20%. Causative factors include ischemia, tension, foreign body reaction, microabscesses, and the negative pressure within the thoracic cavity. Laser assisted tissue sealing (LATS) has been shown to decrease anastomotic leakage rates in other tissues. Using a canine model the efficacy of LATS in enhancing single layer hand swen intrathoracic esophageal anastomoses was assessed. Via a left thoracotomy, paired two centimeter transverse incisions (one laser sealed, one control) were made in the proximal and distal esophagus in nine dogs. Both were sewn using a single layer of 4-0 polyglycolic acid. A combination of albumin (0.2 cc), sodium hyaluronate (0.4 cc), and indocyanine green (1 gtt) was applied to one of the randomly chosen hand sewn repairs. The albumin/hyaluronate combination is used to provide a protein matrix across the anastomosis for ingrowth of fibroblasts. Indocyanine green dye selectively absorbs at OM805 nm which matches the output of the diode laser (808 +/- 1 nm), thus improving uptake of laser energy by the targeted tissues. The anastomosis was then exposed to continuous wave diode laser energy for OM2 minutes at a power density of 9.6 W/cm2. The esophagus was recovered either at the time of sealing or two days postoperatively and infused with saline under pressure. Bursting pressures were considered the point of initial saline leakage. At time 0 there was no significant difference in bursting pressures between the LATS group and controls. However, at two days postoperatively controls burst at 121 +/- 14 mmHg while the laser assisted anastomoses burst at 295 +/- 35 mmHg (p anastomoses revealed minimal thermal injury to the mucosal surface initially, with some regeneration of mucosal lining at two days postoperatively. No foreign body reaction to the solder was noted. Laser reinforcement of single layer hand sewn esophageal anastomoses appears to increase bursting pressure and may result

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.

Evaluation of synthase and hemisynthase activities of glucosamine-6-phosphate synthase by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Gaucher-Wieczorek, Florence; Guérineau, Vincent; Touboul, David; Thétiot-Laurent, Sophie; Pelissier, Franck; Badet-Denisot, Marie-Ange; Badet, Bernard; Durand, Philippe

2014-08-01

Glucosamine-6-phosphate synthase (GlmS, EC 2.6.1.16) catalyzes the first and rate-limiting step in the hexosamine biosynthetic pathway, leading to the synthesis of uridine-5'-diphospho-N-acetyl-D-glucosamine, the major building block for the edification of peptidoglycan in bacteria, chitin in fungi, and glycoproteins in mammals. This bisubstrate enzyme converts D-fructose-6-phosphate (Fru-6P) and L-glutamine (Gln) into D-glucosamine-6-phosphate (GlcN-6P) and L-glutamate (Glu), respectively. We previously demonstrated that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) allows determination of the kinetic parameters of the synthase activity. We propose here to refine the experimental protocol to quantify Glu and GlcN-6P, allowing determination of both hemisynthase and synthase parameters from a single assay kinetic experiment, while avoiding interferences encountered in other assays. It is the first time that MALDI-MS is used to survey the activity of a bisubstrate enzyme. Copyright © 2014 Elsevier Inc. All rights reserved.

Laser assisted drug delivery: a review of an evolving technology.

Science.gov (United States)

Sklar, Lindsay R; Burnett, Christopher T; Waibel, Jill S; Moy, Ronald L; Ozog, David M

2014-04-01

Topically applied drugs have a relatively low cutaneous bioavailability. This article reviews the existing applications of laser assisted drug delivery, a means by which the permeation of topically applied agents can be enhanced into the skin. The existing literature suggests that lasers are a safe and effective means of enhancing the delivery of topically applied agents through the skin. The types of lasers most commonly studied in regards to drug delivery are the carbon dioxide (CO2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) lasers. Both conventional ablative and fractional ablative modalities have been utilized and are summarized herein. The majority of the existing studies on laser assisted drug delivery have been performed on animal models and additional human studies are needed. Laser assisted drug delivery is an evolving technology with potentially broad clinical applications. Multiple studies demonstrate that laser pretreatment of the skin can increase the permeability and depth of penetration of topically applied drug molecules for both local cutaneous and systemic applications. © 2014 Wiley Periodicals, Inc.

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.

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

2016-01-01

ABSTRACT 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. PMID:27795344

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.

Ghost peaks observed after AP-MALDI experiment may disclose new ionization mechanism of matrix assisted hypersonic velocity impact ionization

Science.gov (United States)

Moskovets, Eugene

2015-01-01

RATIONALE Understanding the mechanisms of 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 has 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 laserless matrix-assisted ionization. METHODS An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser was turned off and MALDI sample was 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. RESULTS 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. CONCLUSIONS The observations were partially consistent with a model of

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.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for rapid identification of fungal rhinosinusitis pathogens.

Science.gov (United States)

Huang, Yanfei; Wang, Jinglin; Zhang, Mingxin; Zhu, Min; Wang, Mei; Sun, Yufeng; Gu, Haitong; Cao, Jingjing; Li, Xue; Zhang, Shaoya; Lu, Xinxin

2017-03-01

Filamentous fungi are among the most important pathogens, causing fungal rhinosinusitis (FRS). Current laboratory diagnosis of FRS pathogens mainly relies on phenotypic identification by culture and microscopic examination, which is time consuming and expertise dependent. Although matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS has been employed to identify various fungi, its efficacy in the identification of FRS fungi is less clear. A total of 153 FRS isolates obtained from patients were analysed at the Clinical Laboratory at the Beijing Tongren Hospital affiliated to the Capital Medical University, between January 2014 and December 2015. They were identified by traditional phenotypic methods and Bruker MALDI-TOF MS (Bruker, Biotyper version 3.1), respectively. Discrepancies between the two methods were further validated by sequencing. Among the 153 isolates, 151 had correct species identification using MALDI-TOF MS (Bruker, Biot 3.1, score ≥2.0 or 2.3). MALDI-TOF MS enabled identification of some very closely related species that were indistinguishable by conventional phenotypic methods, including 1/10 Aspergillus versicolor, 3/20 Aspergillus flavus, 2/30 Aspergillus fumigatus and 1/20 Aspergillus terreus, which were misidentified by conventional phenotypic methods as Aspergillus nidulans, Aspergillus oryzae, Aspergillus japonicus and Aspergillus nidulans, respectively. In addition, 2/2 Rhizopus oryzae and 1/1 Rhizopus stolonifer that were identified only to the genus level by the phenotypic method were correctly identified by MALDI-TOF MS. MALDI-TOF MS is a rapid and accurate technique, and could replace the conventional phenotypic method for routine identification of FRS fungi in clinical microbiology laboratories.

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

International Nuclear Information System (INIS)

Ng, Tsz-Tsun; So, Pui-Kin; Zheng, Bo; Yao, Zhong-Ping

2015-01-01

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

New bio-active, antimicrobial and adherent coatings of nanostructured carbon double-reinforced with silver and silicon by Matrix-Assisted Pulsed Laser Evaporation for medical applications

Science.gov (United States)

Duta, L.; Ristoscu, C.; Stan, G. E.; Husanu, M. A.; Besleaga, C.; Chifiriuc, M. C.; Lazar, V.; Bleotu, C.; Miculescu, F.; Mihailescu, N.; Axente, E.; Badiceanu, M.; Bociaga, D.; Mihailescu, Ion N.

2018-05-01

We report on Matrix-Assisted Pulsed Laser Evaporation (MAPLE) deposition of Carbon thin films, simple or reinforced with intended concentrations of Ag and Si. A KrF∗ (λ = 248 nm, τFWHM ≤ 25 ns, ν = 10 Hz) excimer laser was used for irradiation. The effect of a post-deposition thermal treatment in vacuum was studied. Besides detailed morphological, compositional, structural and pull-out adherence characterizations, the potential of the carbonaceous films for medical applications was investigated in vitro by anti-biofilm and cytocompatibility assays. The microscopic images evidenced no delaminations. Micro-Raman spectroscopy revealed a graphitization tendency depending on preparation conditions, thermal treatment and reinforcing agents' presence. Adherence values improved considerably after thermal treatment. In vitro biological evaluation showed that the films containing ∼1.85 at.% Ag were non-cytotoxic for MG63 cells, while eliciting a limited antimicrobial activity. The increase of Ag content to 3.6 at.% results in a significant enhancement of antimicrobial activity, whilst maintaining the cytotoxic action and adherence characteristics at acceptable levels. We propose a new class of metamaterials based on C reinforced with Ag and Si obtained by MAPLE for medical applications, i.e. the prevention and treatment of various infections associated with biofilms developed on implants and other medical equipments.

Matrix Optical Absorption in UV-MALDI MS.

Science.gov (United States)

Robinson, Kenneth N; Steven, Rory T; Bunch, Josephine

2018-03-01

In ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS) matrix compound optical absorption governs the uptake of laser energy, which in turn has a strong influence on experimental results. Despite this, quantitative absorption measurements are lacking for most matrix compounds. Furthermore, despite the use of UV-MALDI MS to detect a vast range of compounds, investigations into the effects of laser energy have been primarily restricted to single classes of analytes. We report the absolute solid state absorption spectra of the matrix compounds α-cyano-4-hydroxycinnamic acid (CHCA), para-nitroaniline (PNA), 2-mercaptobenzothiazole (MBT), 2,5-dihydroxybenzoic acid (2,5-DHB), and 2,4,6-trihydroxyacetophenone (THAP). The desorption/ionization characteristics of these matrix compounds with respect to laser fluence was investigated using mixed systems of matrix with either angiotensin II, PC(34:1) lipid standard, or haloperidol, acting as representatives for typical classes of analyte encountered in UV-MALDI MS. The first absolute solid phase spectra for PNA, MBT, and THAP are reported; additionally, inconsistencies between previously published spectra for CHCA are resolved. In light of these findings, suggestions are made for experimental optimization with regards to matrix and laser wavelength selection. The relationship between matrix optical cross-section and wavelength-dependant threshold fluence, fluence of maximum ion yield, and R, a new descriptor for the change in ion intensity with fluence, are described. A matrix cross-section of 1.3 × 10 -17 cm -2 was identified as a potential minimum for desorption/ionization of analytes. Graphical Abstract ᅟ.

Rapid identification of bacteria in positive blood culture by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

Schmidt, V; Jarosch, A; März, P; Sander, C; Vacata, V; Kalka-Moll, W

2012-03-01

Blood culture is probably the most significant specimen used for the diagnosis of bacterial infections, especially for bloodstream infections. In the present study, we compared the resin-containing BD BACTEC™ Plus-Aerobic (Becton Dickinson), non-charcoal-containing BacT/Alert(®) SA (bioMérieux), and charcoal-containing BacT/Alert(®) FA (bioMérieux) blood culture bottles with direct identification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 103 bacterial isolates, from clinical blood cultures, representing the most frequent 13 genera and 24 species were examined. Bacteria were extracted from positive blood culture broth by density centrifugation and then subjected to identification by MALDI-TOF MS using two different volumes and chemical treatments. Overall, correct identification by MALDI-TOF MS was obtained for the BD BACTEC™ Plus-Aerobic, BacT/Alert(®) SA, and BacT/Alert(®) FA blood culture bottles in 72%, 45.6%, and 23%, respectively, for gram-negative bacteria in 86.6%, 69.2%, and 47.1%, respectively, and for gram-positive bacteria in 60.0%, 28.8%, and 5.4%, respectively. The lack of identification was observed mainly with viridans streptococci. Depending on the blood culture bottles used in routine diagnostic procedures and the protocol for bacterial preparation, the applied MALDI-TOF MS represents an efficient and rapid method for direct bacterial identification.

Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

Science.gov (United States)

Widder, Lukas; Brennerb, Josef; Huttera, Herbert

2014-01-01

To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends.

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry rapid detection of carbapenamase activity in Acinetobacter baumannii isolates

Directory of Open Access Journals (Sweden)

Noha Abouseada

2017-01-01

Full Text Available Introduction: Carbapenamase-producing Acinetobacter baumannii are an increasing threat in hospitals and Intensive Care Units. Accurate and rapid detection of carbapenamase producers has a great impact on patient improvement and aids in implementation of infection control measures. Aim: In this study, we describe the use of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI TOF MS to identify carbapenamase-producing A. baumannii isolates in up to 3 h. Isolates and Methods: A total of 50 A. baumannii isolates (of which 39 were carabapenamase producers were tested using MALDI TOF MS. Isolates were incubated for 3 h with 0.25 mg/ml up to 2 mg/ml of imipenem (IMP at 37°C. Supernatants were analysed by MALDI TOF to analyse peaks corresponding to IMP (300 Da and an IMP metabolite (254 Da using UltrafleXtreme (Bruker Daltonics, Bremen, Germany. Results: All carbapenamase-producing isolates were evidenced by the disappearance or reduction in intensity of the 300 Da peak of IPM and the appearance of a 254 Da peak of the IPM metabolite. In isolates that did not produce carbapenamase, the IPM 300 Da peak remained intact. Conclusion: MALDI TOF is a promising tool in the field of diagnostic microbiology that has the ability to transfer identification and antimicrobial susceptibility testing time from days to hours.

Ceramic matrix composites by microwave assisted CVI

International Nuclear Information System (INIS)

Currier, R.P.; Devlin, D.J.

1993-01-01

Chemical vapor infiltration (CVI) processes for producing continuously reinforced ceramic composites are reviewed. Potential advantages of microwave assisted CVI are noted and numerical studies of microwave assisted CVI are reviewed. The models predict inverted thermal gradients in fibrous ceramic preforms subjected to microwave radiation and suggest processing strategies for achieving uniformly dense composites. Comparisons are made to experimental results on silicon-based composite systems. The role played by the relative ability of fiber and matrix to dissipate microwave energy is noted. Results suggest that microwave induced inverted gradients can be exploited to promote inside-out densification. 10 refs., 2 figs

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

Science.gov (United States)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

The sensitivity of direct identification from positive BacT/ALERT™ (bioMérieux) blood culture bottles by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is low.

Science.gov (United States)

Szabados, F; Michels, M; Kaase, M; Gatermann, S

2011-02-01

Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been presented as a novel method for the direct identification of bacteria from positive blood culture bottles. The rate of the MALDI TOF MS-based identification in the present study from positive BacT/ALERT (bioMérieux, Marcy l'Etoile, France) blood culture bottles was 30%, which is far below the previously reported sensitivities using the BACTEC (Becton Dickinson, Franklin Lakes, NJ, USA) system. We also found evidence that the Biotyper algorithm did not identify a second pathogen in cases of positive BacT/ALERT blood culture bottles containing two different species. © 2010 The Authors. Journal Compilation © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Thermo- and pH-responsive polymer brushes-grafted gigaporous polystyrene microspheres as a high-speed protein chromatography matrix.

Science.gov (United States)

Qu, Jian-Bo; Xu, Yu-Liang; Liu, Jun-Yi; Zeng, Jing-Bin; Chen, Yan-Li; Zhou, Wei-Qing; Liu, Jian-Guo

2016-04-08

Dual thermo- and pH-responsive chromatography has been proposed using poly(N-isopropylacrylamide-co-butyl methacrylate-co-N,N-dimethylaminopropyl acrylamide) (P(NIPAM-co-BMA-co-DMAPAAM)) brushes grafted gigaporous polystyrene microspheres (GPM) as matrix. Atom transfer radical polymerization (ATRP) initiator was first coupled onto GPM through Friedel-Crafts acylation with 2-bromoisobutyryl bromide. The dual-responsive polymer brushes were then grafted onto GPM via surface-initiated ATRP. The surface composition, gigaporous structure, protein adsorption and dual-responsive chromatographic properties of the matrix (GPM-P(NIPAM-co-BMA-co-DMAPAAM) were characterized in detail. Results showed that GPM were successfully grafted with thermoresponsive cationic polymer brushes and that the gigaporous structure was well maintained. A column packed with GPM-P(NIPAM-co-BMA-co-DMAPAAM presented low backpressure, good permeability and appreciable thermo-responsibility. By changing pH of the mobile phase and temperature of the column in turn, the column can separate three model proteins at the mobile phase velocity up to 2528cmh(-1). A separation mechanism of this matrix was also proposed. All results indicate that the dual thermo- and pH-responsive chromatography matrix has great potentials in 'green' high-speed protein chromatography. Copyright © 2016 Elsevier B.V. All rights reserved.

In vitro behavior of human mesenchymal stem cells on poly(N-isopropylacrylamide) based biointerfaces obtained by matrix assisted pulsed laser evaporation

Science.gov (United States)

Icriverzi, Madalina; Rusen, Laurentiu; Sima, Livia Elena; Moldovan, Antoniu; Brajnicov, Simona; Bonciu, Anca; Mihailescu, Natalia; Dinescu, Maria; Cimpean, Anisoara; Roseanu, Anca; Dinca, Valentina

2018-05-01

The use of smart coatings with tunable characteristics in bioengineering fields is directly correlated with the surface chemical and topographical properties, the method of preparation, and also with the type of cells implied for the specific application. In this work, a versatile surface modification technique based on the use of lasers (Matrix-Assisted Pulsed Laser Evaporation (MAPLE)) was used to yield poly(N-isopropylacrylamide) (pNIPAM) and its derivatives (amine, azide and amide terminated pNIPAM) functional and termoresponsive thin films. Surface properties of pNIPAM and its derivative films such as morphology, roughness and hydrophobic/hydrophilic character, as well as the thermoresponsive capacity were investigated by atomic force microscopy and contact angle measurements. The chemical characteristics of the pNIPAM based thin films were analysed by Fourier Transform Infrared Spectroscopy (FTIR). The chemical functionality was kept for all the samples obtained by MAPLE and the thermoresponse was demonstrated by the change in the contact angle and thickness values when the temperature was shifted from 37 °C to 24 °C for all the materials tested, with a smaller change for maleimide terminated pNIPAM. Biological assays performed in vitro (fluorescence microscopy and Scanning Electron Microscopy (SEM)) confirmed the conditioning of the early mesenchymal stem cell (MSC) growth by specific chemistry of the coatings. The cell imaging analysis revealed no cytotoxic effect of pNIPAM surfaces irrespective of type of functionalization. An increased proliferation rate of the cells grown on pNIPAM-azide surfaces and a lower cell density on pNIPAM-maleimide surfaces compared to the pNIPAM surfaces was observed, which can direct their use to potential surfaces in regenerative medicine approaches.

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.

Laser-assisted shape selective fragmentation of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kazakevich, P.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Simakin, A.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation)]. E-mail: shafeev@kapella.gpi.ru; Viau, G. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Soumare, Y. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Bozon-Verduraz, F. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France)

2007-07-31

Experimental results are presented on laser-assisted fragmentation of gold-containing nanoparticles suspended in liquids (either ethanol or water). Two kinds of nanoparticles are considered: (i) elongated Au nanorods synthesized by laser ablation of a gold target immersed in liquid phase; (ii) gold-covered NiCo nanorods with high aspect ratio ({theta} {approx} 10) synthesized by wet chemistry processes. The shape selectivity induced by laser fragmentation of these nanorods is gained via tuning the wavelength of laser radiation into different parts of the spectrum of their plasmon resonance corresponding to different aspect ratios {theta}. Fragmentation is performed using three laser wavelengths, involving a Cu vapour laser (510 and 578 nm) and a Nd:YAG (1064 nm). Nanoparticles are characterized by UV-vis spectrometry, Transmission Electron Microscopy (TEM). The effect of laser pulse duration (nanosecond against picosecond range) is also studied in the case of fragmentation with an IR laser radiation.

Laser Assisted Free-Free Transition in Electron - Atom Collision

Science.gov (United States)

Sinha, C.; Bhatia, A. K.

2011-01-01

Free-free transition is studied for electron-Hydrogen atom system in ground state at very low incident energies in presence of an external homogeneous, monochromatic and linearly polarized laser field. The incident electron is considered to be dressed by the laser in a non perturbative manner by choosing the Volkov solutions in both the channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the effect of electron exchange, short range as well as of the long range interactions. Laser assisted differential as well as elastic total cross sections are calculated for single photon absorption/emission in the soft photon limit, the laser intensity being much less than the atomic field intensity. A strong suppression is noted in the laser assisted cross sections as compared to the field free situations. Significant difference is noted in the singlet and the triplet cross sections.

Discrimination of Aspergillus isolates at the species and strain level by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry fingerprinting.

Science.gov (United States)

Hettick, Justin M; Green, Brett J; Buskirk, Amanda D; Kashon, Michael L; Slaven, James E; Janotka, Erika; Blachere, Francoise M; Schmechel, Detlef; Beezhold, Donald H

2008-09-15

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to generate highly reproducible mass spectral fingerprints for 12 species of fungi of the genus Aspergillus and 5 different strains of Aspergillus flavus. Prior to MALDI-TOF MS analysis, the fungi were subjected to three 1-min bead beating cycles in an acetonitrile/trifluoroacetic acid solvent. The mass spectra contain abundant peaks in the range of 5 to 20kDa and may be used to discriminate between species unambiguously. A discriminant analysis using all peaks from the MALDI-TOF MS data yielded error rates for classification of 0 and 18.75% for resubstitution and cross-validation methods, respectively. If a subset of 28 significant peaks is chosen, resubstitution and cross-validation error rates are 0%. Discriminant analysis of the MALDI-TOF MS data for 5 strains of A. flavus using all peaks yielded error rates for classification of 0 and 5% for resubstitution and cross-validation methods, respectively. These data indicate that MALDI-TOF MS data may be used for unambiguous identification of members of the genus Aspergillus at both the species and strain levels.

Multi-imaging of Cytokinin and Abscisic Acid on the Roots of Rice (Oryza sativa) Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

Science.gov (United States)

Shiono, Katsuhiro; Hashizaki, Riho; Nakanishi, Toyofumi; Sakai, Tatsuko; Yamamoto, Takushi; Ogata, Koretsugu; Harada, Ken-Ichi; Ohtani, Hajime; Katano, Hajime; Taira, Shu

2017-09-06

Plant hormones act as important signaling molecules that regulate responses to abiotic stress as well as plant growth and development. Because their concentrations of hormones control the physiological responses in the target tissue, it is important to know the distributions and concentrations in the tissues. However, it is difficult to determine the hormone concentration on the plant tissue as a result of the limitations of conventional methods. Here, we report the first multi-imaging of two plant hormones, one of cytokinin [i.e., trans-zeatin (tZ)] and abscisic acid (ABA) using a new technology, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) imaging. Protonated signals of tZ (m/z 220.1) and ABA (m/z 265.3) were chosen on longitudinal sections of rice roots for MS imaging. tZ was broadly distributed about 40 mm behind the root apex but was barely detectable at the apex, whereas ABA was mainly detected at the root apex. Multi-imaging using MALDI-TOF-MS enabled the visualization of the localization and quantification of plant hormones. Thus, this tool is applicable to a wide range of plant species growing under various environmental conditions.

Visualization of dynamic change in contraction-induced lipid composition in mouse skeletal muscle by matrix-assisted laser desorption/ionization imaging mass spectrometry.

Science.gov (United States)

Goto-Inoue, Naoko; Manabe, Yasuko; Miyatake, Shouta; Ogino, Shinya; Morishita, Ai; Hayasaka, Takahiro; Masaki, Noritaka; Setou, Mitsutoshi; Fujii, Nobuharu L

2012-06-01

Lipids in skeletal muscle play a fundamental role both in normal muscle metabolism and in disease states. Skeletal muscle lipid accumulation is associated with several chronic metabolic disorders, including obesity, insulin resistance, and type 2 diabetes. However, it is poorly understood whether the lipid composition of skeletal muscle changes by contraction, due to the complexity of lipid molecular species. In this study, we used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to investigate changes in skeletal muscle lipid composition induced by contraction. We successfully observed the reduction of diacylglycerol and triacylglycerol, which are generally associated with muscle contraction. Interestingly, we found the accumulation of some saturated and mono-unsaturated fatty acids and poly-unsaturated fatty acids containing phosphatidylcholine in contracted muscles. Moreover, the distributions of several types of lipid were changed by contraction. Our results show that changes in the lipid amount, lipid composition, and energy metabolic activity can be evaluated in each local spot of cells and tissues at the same time using MALDI-IMS. In conclusion, MALDI-IMS is a powerful tool for studying lipid changes associated with contractions.

Laser-assisted delivery of topical methotrexate - in vitro investigations

DEFF Research Database (Denmark)

Taudorf, Elisabeth Hjardem

2016-01-01

of the correlation between laser parameters and tissue effects was used to deliver methotrexate (MTX) topically through microscopic ablation zones (MAZs) of precise dimensions. MTX is a well-known chemotherapeutic and anti-inflammatory drug that may cause systemic adverse effects, and topical delivery is thus......Ablative fractional lasers (AFXL) are increasingly used to treat dermatological disorders and to facilitate laser-assisted topical drug delivery. In this thesis, laser-tissue interactions generated by stacked pulses with a miniaturized low-power 2,940 nm AFXL were characterized (study I). Knowledge...... zones of varying thickness. The ratio of skin deposition versus transdermal permeation was constant, regardless of MAZ depth. Impact of transport kinetics on AFXL-assisted topical MTX delivery: MTX accumulated rapidly in AFXL-processed skin. MTX was detectable in mid-dermis after 15 min. and saturated...

Dual ultrasonic-assisted dispersive liquid-liquid microextraction coupled with microwave-assisted derivatization for simultaneous determination of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol by ultra high performance liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Zhao, Xian-En; Lv, Tao; Zhu, Shuyun; Qu, Fei; Chen, Guang; He, Yongrui; Wei, Na; Li, Guoliang; Xia, Lian; Sun, Zhiwei; Zhang, Shijuan; You, Jinmao; Liu, Shu; Liu, Zhiqiang; Sun, Jing; Liu, Shuying

2016-03-11

This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4'-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser assisted robotic surgery in cornea transplantation

Science.gov (United States)

Rossi, Francesca; Micheletti, Filippo; Magni, Giada; Pini, Roberto; Menabuoni, Luca; Leoni, Fabio; Magnani, Bernardo

2017-03-01

Robotic surgery is a reality in several surgical fields, such as in gastrointestinal surgery. In ophthalmic surgery the required high spatial precision is limiting the application of robotic system, and even if several attempts have been designed in the last 10 years, only some application in retinal surgery were tested in animal models. The combination of photonics and robotics can really open new frontiers in minimally invasive surgery, improving the precision, reducing tremor, amplifying scale of motion, and automating the procedure. In this manuscript we present the preliminary results in developing a vision guided robotic platform for laser-assisted anterior eye surgery. The robotic console is composed by a robotic arm equipped with an "end effector" designed to deliver laser light to the anterior corneal surface. The main intended application is for laser welding of corneal tissue in laser assisted penetrating keratoplasty and endothelial keratoplasty. The console is equipped with an integrated vision system. The experiment originates from a clear medical demand in order to improve the efficacy of different surgical procedures: when the prototype will be optimized, other surgical areas will be included in its application, such as neurosurgery, urology and spinal surgery.

Dependence of laser assisted cleaning of clad surfaces on the laser fluence

International Nuclear Information System (INIS)

Nilaya, J.P.; Raote, P.; Sai Prasad, M.B.; Biswas, D.J.; Aniruddha Kumar

2005-01-01

The decontamination factor is studied as a function of laser fluence for three kinds of clad surfaces viz., plain zircaloy, autoclaved zircaloy and SS with cesium as the test contamination. It has been found that the decontamination factor exhibits a maximal behaviour with the laser fluence and its maximum value occurs at different laser fluences in the three cases. The maximal behaviour is attributed to reduced coupling of energy from the laser beam to the substrate due to the initiation of surface-assisted optical breakdown. The results obtained in the experiment carried out in helium environment qualitatively support this explanation (author)

CO2-laser-assisted processing of glass fiber-reinforced thermoplastic composites

Science.gov (United States)

Brecher, Christian; Emonts, Michael; Schares, Richard Ludwig; Stimpfl, Joffrey

2013-02-01

To fully exploit the potential of fiber-reinforced thermoplastic composites (FRTC) and to achieve a broad industrial application, automated manufacturing systems are crucial. Investigations at Fraunhofer IPT have proven that the use of laser system technology in processing FRTC allows to achieve high throughput, quality, flexibility, reproducibility and out-of-autoclave processing simultaneously. As 90% of the FRP in Europe1 are glass fiber-reinforced a high impact can be achieved by introducing laser-assisted processing with all its benefits to glass fiber-reinforced thermoplastics (GFRTC). Fraunhofer IPT has developed the diode laser-assisted tape placement (laying and winding) to process carbon fiber-reinforced thermoplastic composites (CFRTC) for years. However, this technology cannot be transferred unchanged to process milky transparent GFRTC prepregs (preimpregnated fibers). Due to the short wavelength (approx. 980 nm) and therefore high transmission less than 20% of the diode laser energy is absorbed as heat into non-colored GFRTC prepregs. Hence, the use of a different wave length, e.g. CO2-laser (10.6 μm) with more than 90% laser absorption, is required to allow the full potential of laser-assisted processing of GFRTC. Also the absorption of CO2-laser radiation at the surface compared to volume absorption of diode laser radiation is beneficial for the interlaminar joining of GFRTC. Fraunhofer IPT is currently developing and investigating the CO2-laser-assisted tape placement including new system, beam guiding, process and monitoring technology to enable a resource and energy efficient mass production of GFRP composites, e.g. pipes, tanks, masts. The successful processing of non-colored glass fiber-reinforced Polypropylene (PP) and Polyphenylene Sulfide (PPS) has already been proven.

Laser-assisted printing of alginate long tubes and annular constructs

International Nuclear Information System (INIS)

Yan Jingyuan; Huang Yong; Chrisey, Douglas B

2013-01-01

Laser-assisted printing such as laser-induced forward transfer has been well studied to pattern or fabricate two-dimensional constructs. In particular, laser printing has found increasing biomedical applications as an orifice-free cell and organ printing approach, especially for highly viscous biomaterials and biological materials. Unfortunately, there have been very few studies on the efficacy of three-dimensional printing performance of laser printing. This study has investigated the feasibility of laser tube printing and the effects of sodium alginate concentration and operating conditions such as the laser fluence and laser spot size on the printing quality during laser-assisted printing of alginate annular constructs (short tubes) with a nominal diameter of 3 mm. It is found that highly viscous materials such as alginate can be printed into well-defined long tubes and annular constructs. The tube wall thickness and tube outer diameter decrease with the sodium alginate concentration, while they first increase, then decrease and finally increase again with the laser fluence. The sodium alginate concentration dominates if the laser fluence is low, and the laser fluence dominates if the sodium alginate concentration is low. (paper)

Combustion-assisted laser cutting of a difficult-to-machine superalloy

International Nuclear Information System (INIS)

Molian, P.A.

1992-01-01

In laser cutting, the largest single application of lasers in manufacturing, the assist gas plays an important role in affecting the cutting performance. The assist gas is usually oxygen or an inert gas. In this paper acetylene and oxygen was employed to create combustion reactions during CO 2 laser cutting that enabled an improvement in the cutting speed, and cut quality of a difficult-to-machine superalloy. A comparison with laser cutting of a plain carbon steel under identical conditions was also made to determine the usefulness of combustion energy. Results indicate that both cutting speed and quality are enhanced by the reduction in the viscosity of slag formed during cutting (which assisted in ejection of the slag through the bottom of the kerf) due to the heat released by the acetylene burning inside the kerf. Correlations of experimental data with a theoretical model provided the influence of combustion power and gas-flow power on the cutting phenomena

Multivariate analysis of matrix-assisted laser desorption/ionization mass spectrometric data related to glycoxidation products of human globins in nephropathic patients.

Science.gov (United States)

Lapolla, Annunziata; Ragazzi, Eugenio; Andretta, Barbara; Fedele, Domenico; Tubaro, Michela; Seraglia, Roberta; Molin, Laura; Traldi, Pietro

2007-06-01

To clarify the possible pathogenetic role of oxidation products originated from the glycation of proteins, human globins from nephropathic patients have been studied by matrix-assisted laser desorption/ionization mass spectrometry (MALDI), revealing not only unglycated and monoglycated globins, but also a series of different species. For the last ones, structural assignments were tentatively done on the basis of observed masses and expectations for the Maillard reaction pattern. Consequently, they must be considered only propositive, and the discussion which will follow must be considered in this view. In our opinion this approach does not seem to compromise the intended diagnostic use of the data because distinctions are valid even if the assignments are uncertain. We studied nine healthy subjects and 19 nephropathic patients and processed the data obtained from the MALDI spectra using a multivariate analysis. Our results showed that multivariate analytical techniques enable differential aspects of the profile of molecular species to be identified in the blood of end stage nephropathic patients. A correct grouping can be achieved by principal component analysis (PCA) and the results suggest that several products involved in carbonyl stress exist in nephropathic patients. These compounds may have a relevant role as specific markers of the pathological state.

Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.

Science.gov (United States)

Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

2014-05-01

The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems.

Straylight before and after hyperopic laser in situ keratomileusis or laser-assisted subepithelial keratectomy

NARCIS (Netherlands)

Lapid-Gortzak, Ruth; van der Linden, Jan Willem; van der Meulen, Ivanka J. E.; Nieuwendaal, Carla P.; Mourits, Maarten P.; van den Berg, Thomas J. T. P.

2010-01-01

PURPOSE To compare straylight values before and 3 months after hyperopic laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) and determine the cause of any change SETTING Private refractive surgery clinic, Driebergen, The Netherlands DESIGN Comparative case

Straylight measurements in laser in situ keratomileusis and laser-assisted subepithelial keratectomy for myopia

NARCIS (Netherlands)

Lapid-Gortzak, Ruth; van der Linden, Jan Willem; van der Meulen, Ivanka; Nieuwendaal, Carla; van den Berg, Tom

2010-01-01

PURPOSE: To compare straylight values before and 3 months after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) and to analyze the causes of any change. SETTING: Private refractive surgery clinic, Driebergen, The Netherlands. METHODS: Straylight was measured

Effect of laser energy, substrate film thickness and bioink viscosity on viability of endothelial cells printed by Laser-Assisted Bioprinting

Science.gov (United States)

Catros, Sylvain; Guillotin, Bertrand; Bačáková, Markéta; Fricain, Jean-Christophe; Guillemot, Fabien

2011-04-01

Biofabrication of three dimensional tissues by Laser-Assisted Bioprinting (LAB) implies to develop specific strategies for assembling the extracellular matrix (ECM) and cells. Possible strategies consist in (i) printing cells onto or in the depth of ECM layer and/or (ii) printing bioinks containing both cells and ECM-like printable biomaterial. The aim of this article was to evaluate combinatorial effects of laser pulse energy, ECM thickness and viscosity of the bioink on cell viability. A LAB workstation was used to print Ea.hy926 endothelial cells onto a quartz substrate covered with a film of ECM mimicking Matrigel™. Hence, effect of laser energy, Matrigel™ film thickness and bioink viscosity was addressed for different experimental conditions (8-24 μJ, 20-100 μm and 40-110 mPa s, respectively). Cell viability was assessed by live/dead assay performed 24 h post-printing. Results show that increasing the laser energy tends to augment the cell mortality while increasing the thickness of the Matrigel™ film and the viscosity of the bioink support cell viability. Hence, critical printing parameters influencing high cell viability have been related to the cell landing conditions and more specifically to the intensity of the cell impacts occurring at the air-ECM interface and at the ECM-glass interface.

Identification of Cronobacter species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with an optimized analysis method.

Science.gov (United States)

Wang, Qi; Zhao, Xiao-Juan; Wang, Zi-Wei; Liu, Li; Wei, Yong-Xin; Han, Xiao; Zeng, Jing; Liao, Wan-Jin

2017-08-01

Rapid and precise identification of Cronobacter species is important for foodborne pathogen detection, however, commercial biochemical methods can only identify Cronobacter strains to genus level in most cases. To evaluate the power of mass spectrometry based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) for Cronobacter species identification, 51 Cronobacter strains (eight reference and 43 wild strains) were identified by both MALDI-TOF MS and 16S rRNA gene sequencing. Biotyper RTC provided by Bruker identified all eight reference and 43 wild strains as Cronobacter species, which demonstrated the power of MALDI-TOF MS to identify Cronobacter strains to genus level. However, using the Bruker's database (6903 main spectra products) and Biotyper software, the MALDI-TOF MS analysis could not identify the investigated strains to species level. When MALDI-TOF MS analysis was performed using the combined in-house Cronobacter database and Bruker's database, bin setting, and unweighted pair group method with arithmetic mean (UPGMA) clustering, all the 51 strains were clearly identified into six Cronobacter species and the identification accuracy increased from 60% to 100%. We demonstrated that MALDI-TOF MS was reliable and easy-to-use for Cronobacter species identification and highlighted the importance of establishing a reliable database and improving the current data analysis methods by integrating the bin setting and UPGMA clustering. Copyright © 2017. Published by Elsevier B.V.

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

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.

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.

Water ice as a matrix for film production by matrix-assisted pulsed laser evaporation (MAPLE)

International Nuclear Information System (INIS)

Rodrigo, K; Schou, J; Toftmann, B; Pedrys, R

2007-01-01

We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above -50deg. C of the target holder the deposition rate increases strongly, but the evaporation pressure in the MAPLE chamber also increases drastically

Water ice as a matrix for film production by matrix assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Rodrigo, Katarzyna Agnieszka; Schou, Jørgen; Christensen, Bo Toftmann

2007-01-01

We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above -50 degrees C...... of the target holder the deposition rate increases strongly, but the evaporation pressure in the MAPLE chamber also increases drastically....

The differences in matrix effect between supercritical fluid chromatography and reversed phase liquid chromatography coupled to ESI/MS.

Science.gov (United States)

Svan, Alfred; Hedeland, Mikael; Arvidsson, Torbjörn; Pettersson, Curt E

2018-02-13

For many sample matrices, matrix effects are a troublesome phenomenon using the electrospray ionization source. The increasing use of supercritical fluid chromatography with CO 2 in combination with the electrospray ionization source for MS detection is therefore raising questions: is the matrix effect behaving differently using SFC in comparison with reversed phase LC? This was investigated using urine, plasma, influent- and effluent-wastewater as sample matrices. The matrix effect was evaluated using the post-extraction addition method and through post-column infusions. Matrix effect profiles generated from the post-column infusions in combination with time of flight-MS detection provided the most valuable information for the study. The combination of both qualitative and semi-quantitative information with the ability to use HRMS-data for identifying interfering compounds from the same experiment was very useful, and has to the authors' knowledge not been used this way before. The results showed that both LC and SFC are affected by matrix effects, however differently depending on sample matrix. Generally, both suppressions and enhancements were seen, with a higher amount of enhancements for LC, where 65% of all compounds and all sample matrices were enhanced, compared to only 7% for SFC. Several interferences were tentatively identified, with phospholipids, creatinine, and metal ion clusters as examples of important interferences, with different impact depending on chromatographic technique. SFC needs a different strategy for limiting matrix interferences, owing to its almost reverse retention order compared to RPLC. Copyright © 2017 Elsevier B.V. All rights reserved.

Mass Spectrometry for Research and Application in Therapeutic Drug Monitoring or Clinical and Forensic Toxicology.

Science.gov (United States)

Maurer, Hans H

2018-04-30

This paper reviews current applications of various hyphenated low- and high-resolution mass spectrometry techniques in the field of therapeutic drug monitoring and clinical/forensic toxicology in both research and practice. They cover gas chromatography, liquid chromatography, matrix-assisted laser desorption ionization, or paper spray ionization coupled to quadrupole, ion trap, time-of-flight, or Orbitrap mass analyzers.

Direct detection of the plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae in infected rice seedlings using matrix assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Kajiwara, Hideyuki

2016-01-01

The plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae were directly detected in extracts from infected rice seedlings by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method did not require culturing of the pathogens on artificial medium. In the MALDI-TOF MS analysis, peaks originating from bacteria were found in extracts from infected rice seedlings. The spectral peaks showed significantly high scores, in spite of minor differences in spectra. The spectral peaks originating from host plant tissues did not affect this direct MALDI-TOF MS analysis for the rapid identification of plant pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.

Translational medicine in the field of ablative fractional laser (AFXL)-assisted drug delivery

DEFF Research Database (Denmark)

Haedersdal, Merete; Erlendsson, Andrés M; Paasch, Uwe

2016-01-01

Ablative fractional lasers enhance uptake of topical therapeutics and the concept of fractional laser-assisted drug delivery has now been taken into clinical practice. Objectives We systematically reviewed preclinical data and clinical evidence for fractional lasers to enhance drug uptake...... level of evidence was reached for actinic keratoses treated with methylaminolevulinate for photodynamic therapy (level IB, 5 randomized controlled trials), substantiating superior and long-lasting efficacy versus conventional photodynamic therapy. No adverse events were reported, but ablative fractional...... laser-assisted drug delivery implies risks of systemic drug absorption, especially when performed over large skin areas. Conclusions Fractional laser-assisted drug delivery is beneficial in enhancing preclinical and clinical outcomes for certain skin conditions....

Delineation of Stenotrophomonas maltophilia isolates from cystic fibrosis patients by fatty acid methyl ester profiles and matrix-assisted laser desorption/ionization time-of-flight mass spectra using hierarchical cluster analysis and principal component analysis.

Science.gov (United States)

Vidigal, Pedrina Gonçalves; Mosel, Frank; Koehling, Hedda Luise; Mueller, Karl Dieter; Buer, Jan; Rath, Peter Michael; Steinmann, Joerg

2014-12-01

Stenotrophomonas maltophilia is an opportunist multidrug-resistant pathogen that causes a wide range of nosocomial infections. Various cystic fibrosis (CF) centres have reported an increasing prevalence of S. maltophilia colonization/infection among patients with this disease. The purpose of this study was to assess specific fingerprints of S. maltophilia isolates from CF patients (n = 71) by investigating fatty acid methyl esters (FAMEs) through gas chromatography (GC) and highly abundant proteins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and to compare them with isolates obtained from intensive care unit (ICU) patients (n = 20) and the environment (n = 11). Principal component analysis (PCA) of GC-FAME patterns did not reveal a clustering corresponding to distinct CF, ICU or environmental types. Based on the peak area index, it was observed that S. maltophilia isolates from CF patients produced significantly higher amounts of fatty acids in comparison with ICU patients and the environmental isolates. Hierarchical cluster analysis (HCA) based on the MALDI-TOF MS peak profiles of S. maltophilia revealed the presence of five large clusters, suggesting a high phenotypic diversity. Although HCA of MALDI-TOF mass spectra did not result in distinct clusters predominantly composed of CF isolates, PCA revealed the presence of a distinct cluster composed of S. maltophilia isolates from CF patients. Our data suggest that S. maltophilia colonizing CF patients tend to modify not only their fatty acid patterns but also their protein patterns as a response to adaptation in the unfavourable environment of the CF lung. © 2014 The Authors.

Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: characterization by internal transcribed spacer, β-Tubulin, and calmodulin gene sequencing, metabolic fingerprinting, and matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Tam, Emily W T; Chen, Jonathan H K; Lau, Eunice C L; Ngan, Antonio H Y; Fung, Kitty S C; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

2014-04-01

Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, β-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. β-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability.

Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: Characterization by Internal Transcribed Spacer, β-Tubulin, and Calmodulin Gene Sequencing, Metabolic Fingerprinting, and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Science.gov (United States)

Tam, Emily W. T.; Chen, Jonathan H. K.; Lau, Eunice C. L.; Ngan, Antonio H. Y.; Fung, Kitty S. C.; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung

2014-01-01

Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, β-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. β-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability. PMID:24452174

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

High laser-fluence deposition of organic materials in water ice matrices by ''MAPLE''

DEFF Research Database (Denmark)

Christensen, Bo Toftmann; Rodrigo, K.; Schou, Jørgen

2005-01-01

Matrix assisted pulsed laser evaporation (MAPLE) is a deposition technique for organic material. Water ice was used as a matrix for the biotechnologically important guest material, polyethylene glycol (PEG), for concentrations from 0.5 to 4 wt.%. The target was irradiated with 6 ns laser pulses...

Microorganisms direct identification from blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Ferreira, L; Sánchez-Juanes, F; Porras-Guerra, I; García-García, M I; García-Sánchez, J E; González-Buitrago, J M; Muñoz-Bellido, J L

2011-04-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows a fast and reliable bacterial identification from culture plates. Direct analysis of clinical samples may increase its usefulness in samples in which a fast identification of microorganisms can guide empirical treatment, such as blood cultures (BC). Three hundred and thirty BC, reported as positive by the automated BC incubation device, were processed by conventional methods for BC processing, and by a fast method based on direct MALDI-TOF MS. Three hundred and eighteen of them yield growth on culture plates, and 12 were false positive. The MALDI-TOF MS-based method reported that no peaks were found, or the absence of a reliable identification profile, in all these false positive BC. No mixed cultures were found. Among these 318 BC, we isolated 61 Gram-negatives (GN), 239 Gram-positives (GP) and 18 fungi. Microorganism identifications in GN were coincident with conventional identification, at the species level, in 83.3% of BC and, at the genus level, in 96.6%. In GP, identifications were coincident with conventional identification in 31.8% of BC at the species level, and in 64.8% at the genus level. Fungaemia was not reliably detected by MALDI-TOF. In 18 BC positive for Candida species (eight C. albicans, nine C. parapsilosis and one C. tropicalis), no microorganisms were identified at the species level, and only one (5.6%) was detected at the genus level. The results of the present study show that this fast, MALDI-TOF MS-based method allows bacterial identification directly from presumptively positive BC in a short time (<30 min), with a high accuracy, especially when GN bacteria are involved. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Laser-assisted vacuum arc extreme ultraviolet source: a comparison of picosecond and nanosecond laser triggering

Science.gov (United States)

Beyene, Girum A.; Tobin, Isaac; Juschkin, Larissa; Hayden, Patrick; O'Sullivan, Gerry; Sokell, Emma; Zakharov, Vassily S.; Zakharov, Sergey V.; O'Reilly, Fergal

2016-06-01

Extreme ultraviolet (EUV) light generation by hybrid laser-assisted vacuum arc discharge plasmas, utilizing Sn-coated rotating-disc-electrodes, was investigated. The discharge was initiated by localized ablation of the liquid tin coating of the cathode disc by a laser pulse. The laser pulse, at 1064 nm, was generated by Nd:YAG lasers with variable energy from 1 to 100 mJ per pulse. The impact of shortening the laser pulse from 7 ns to 170 ps on the EUV generation has been investigated in detail. The use of ps pulses resulted in an increase in emission of EUV radiation. With a fixed discharge energy of ~4 J, the EUV conversion efficiency tends to plateau at ~2.4  ±  0.25% for the ps laser pulses, while for the ns pulses, it saturates at ~1.7  ±  0.3%. Under similar discharge and laser energy conditions, operating the EUV source with the ps-triggering resulted also in narrower spectral profiles of the emission in comparison to ns-triggering. The results indicate an advantage in using ps-triggering in laser-assisted discharges to produce brighter plasmas required for applications such as metrology.

Identification by Molecular Methods and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry and Antifungal Susceptibility Profiles of Clinically Significant Rare Aspergillus Species in a Referral Chest Hospital in Delhi, India.

Science.gov (United States)

Masih, Aradhana; Singh, Pradeep K; Kathuria, Shallu; Agarwal, Kshitij; Meis, Jacques F; Chowdhary, Anuradha

2016-09-01

Aspergillus species cause a wide spectrum of clinical infections. Although Aspergillus fumigatus and Aspergillus flavus remain the most commonly isolated species in aspergillosis, in the last decade, rare and cryptic Aspergillus species have emerged in diverse clinical settings. The present study analyzed the distribution and in vitro antifungal susceptibility profiles of rare Aspergillus species in clinical samples from patients with suspected aspergillosis in 8 medical centers in India. Further, a matrix-assisted laser desorption ionization-time of flight mass spectrometry in-house database was developed to identify these clinically relevant Aspergillus species. β-Tubulin and calmodulin gene sequencing identified 45 rare Aspergillus isolates to the species level, except for a solitary isolate. They included 23 less common Aspergillus species belonging to 12 sections, mainly in Circumdati, Nidulantes, Flavi, Terrei, Versicolores, Aspergillus, and Nigri Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identified only 8 (38%) of the 23 rare Aspergillus isolates to the species level. Following the creation of an in-house database with the remaining 14 species not available in the Bruker database, the MALDI-TOF MS identification rate increased to 95%. Overall, high MICs of ≥2 μg/ml were noted for amphotericin B in 29% of the rare Aspergillus species, followed by voriconazole in 20% and isavuconazole in 7%, whereas MICs of >0.5 μg/ml for posaconazole were observed in 15% of the isolates. Regarding the clinical diagnoses in 45 patients with positive rare Aspergillus species cultures, 19 (42%) were regarded to represent colonization. In the remaining 26 patients, rare Aspergillus species were the etiologic agent of invasive, chronic, and allergic bronchopulmonary aspergillosis, allergic fungal rhinosinusitis, keratitis, and mycetoma. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Identification by Molecular Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Antifungal Susceptibility Profiles of Clinically Significant Rare Aspergillus Species in a Referral Chest Hospital in Delhi, India

Science.gov (United States)

Masih, Aradhana; Singh, Pradeep K.; Kathuria, Shallu; Agarwal, Kshitij

2016-01-01

Aspergillus species cause a wide spectrum of clinical infections. Although Aspergillus fumigatus and Aspergillus flavus remain the most commonly isolated species in aspergillosis, in the last decade, rare and cryptic Aspergillus species have emerged in diverse clinical settings. The present study analyzed the distribution and in vitro antifungal susceptibility profiles of rare Aspergillus species in clinical samples from patients with suspected aspergillosis in 8 medical centers in India. Further, a matrix-assisted laser desorption ionization–time of flight mass spectrometry in-house database was developed to identify these clinically relevant Aspergillus species. β-Tubulin and calmodulin gene sequencing identified 45 rare Aspergillus isolates to the species level, except for a solitary isolate. They included 23 less common Aspergillus species belonging to 12 sections, mainly in Circumdati, Nidulantes, Flavi, Terrei, Versicolores, Aspergillus, and Nigri. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identified only 8 (38%) of the 23 rare Aspergillus isolates to the species level. Following the creation of an in-house database with the remaining 14 species not available in the Bruker database, the MALDI-TOF MS identification rate increased to 95%. Overall, high MICs of ≥2 μg/ml were noted for amphotericin B in 29% of the rare Aspergillus species, followed by voriconazole in 20% and isavuconazole in 7%, whereas MICs of >0.5 μg/ml for posaconazole were observed in 15% of the isolates. Regarding the clinical diagnoses in 45 patients with positive rare Aspergillus species cultures, 19 (42%) were regarded to represent colonization. In the remaining 26 patients, rare Aspergillus species were the etiologic agent of invasive, chronic, and allergic bronchopulmonary aspergillosis, allergic fungal rhinosinusitis, keratitis, and mycetoma. PMID:27413188

Matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry of beta-(1 --> 3), beta-(1 --> 4)-xylans from Nothogenia fastigiata using nor-harmane as matrix.

Science.gov (United States)

Fukuyama, Yuko; Kolender, Adriana A; Nishioka, Masae; Nonami, Hiroshi; Matulewicz, María C; Erra-Balsells, Rosa; Cerezo, Alberto S

2005-01-01

Three xylan fractions isolated from the red seaweed Nothogenia fastigiata (Nemaliales) were analyzed by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOFMS). UV-MALDI-TOFMS was carried out in the linear and reflectron modes, and as routine in the positive and negative ion modes. Of the several matrices tested, nor-harmane was the only effective one giving good spectra in the positive ion mode. The number-average molar masses of two of the fractions, calculated from the distribution profiles, were lower than those determined previously by (1)H NMR analysis, suggesting a decrease in the ionization efficiency with increasing molecular weight; weight-average molar mass and polydispersity index were also determined. As the xylans retained small but significant quantities of calcium salts, the influence of added Ca(2+) as CaCl(2) on UV-MALDI-MS was investigated. The simultaneous addition of sodium chloride and calcium chloride was also analyzed. Addition of sodium chloride did not change the distribution profile of the native sample showing that the inhibitory effect is due to Ca(2+) and not to Cl(-). Addition of calcium chloride with 1:1 analyte/salt molar ratio gave spectra with less efficient desorption/ionization of oligomers; the signals of these oligomers were completely suppressed when the addition of the salt became massive (1:100 analyte/salt molar ratio). Copyright (c) 2005 John Wiley & Sons, Ltd.

Pulsed laser deposition of the lysozyme protein: an unexpected “Inverse MAPLE” process

DEFF Research Database (Denmark)

Schou, Jørgen; Matei, Andreea; Constantinescu, Catalin

2012-01-01

Films of organic materials are commonly deposited by laser assisted methods, such as MAPLE (matrix-assisted pulsed laser evaporation), where a few percent of the film material in the target is protected by a light-absorbing volatile matrix. Another possibility is to irradiate the dry organic...... the ejection and deposition of lysozyme. This can be called an “inverse MAPLE” process, since the ratio of “matrix” to film material in the target is 10:90, which is inverse of the typical MAPLE process where the film material is dissolved in the matrix down to several wt.%. Lysozyme is a well-known protein...

Laser-assisted vascular anastomosis

Science.gov (United States)

Kao, Race L.; Tsao-Wu, George; Magovern, George J.

1990-06-01

The milliwatt CO2 laser and a thermal activated binding compound (20% serum albumin) were used for microvascular anastomoses. Under general anesthesia, the femoral arteries (0.7 to 1.0 mm diameter) of 6 rats were isolated. After the left femoral artery in each rat was clamped and transected, the vessel was held together with 3 equidistant 10-0 Xomed sutures. The cut edges were coated 3 to 4 times with the albumin solution and sealed with the CO2 laser (power density = 120 W/cm2). The binding compound solidified to a translucent tensile substance which supported the anastomosis until self healing and repair were achieved. The right femoral artery was used as sham operated control. Complete hemostasis and patency were observed in every case immediately and at 1, 3, and 6 months following surgery. The binding compound absorbed most of the laser energy thus minimizing thermal injury to the underlying tissue. Mongrel dogs weighing 28 to 33 kg were anesthetized and prepared for sterile surgical procedures. In 5 dogs, the femoral and jugular veins were exposed, transected, and anastomosed using a CO2 laser (Sharplan 1040) with the binding compound. In another 12 dogs, cephalic veins were isolated and used for aortocoronary artery bypass procedures. The Sharplan 1040 CO2 laser and 20% albumin solution were utilized to complete the coronary anastomoses in 6 dogs, and 6 dogs were used as controls by suturing the vessels. Again, hemostasis, patency, and minimal tissue damage were observed immediately and 6 weeks after the procedures. Improved surgical results, reduced operating time, minimized tissue damage, and enhanced anastomotic integrity are the advantages of laser assisted vascular anastomosis with a thermal activated binding compound.

Evaluation of VITEK mass spectrometry (MS), a matrix-assisted laser desorption ionization time-of-flight MS system for identification of anaerobic bacteria.

Science.gov (United States)

Lee, Wonmok; Kim, Myungsook; Yong, Dongeun; Jeong, Seok Hoon; Lee, Kyungwon; Chong, Yunsop

2015-01-01

By conventional methods, the identification of anaerobic bacteria is more time consuming and requires more expertise than the identification of aerobic bacteria. Although the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems are relatively less studied, they have been reported to be a promising method for the identification of anaerobes. We evaluated the performance of the VITEK MS in vitro diagnostic (IVD; 1.1 database; bioMérieux, France) in the identification of anaerobes. We used 274 anaerobic bacteria isolated from various clinical specimens. The results for the identification of the bacteria by VITEK MS were compared to those obtained by phenotypic methods and 16S rRNA gene sequencing. Among the 249 isolates included in the IVD database, the VITEK MS correctly identified 209 (83.9%) isolates to the species level and an additional 18 (7.2%) at the genus level. In particular, the VITEK MS correctly identified clinically relevant and frequently isolated anaerobic bacteria to the species level. The remaining 22 isolates (8.8%) were either not identified or misidentified. The VITEK MS could not identify the 25 isolates absent from the IVD database to the species level. The VITEK MS showed reliable identifications for clinically relevant anaerobic bacteria.

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.

Laser assisted removal of fixed contamination from metallic substrate

International Nuclear Information System (INIS)

Kumar, Aniruddha; Prasad, Manisha; Prakash, Tej; Shail, Shailini; Bhatt, R.B.; Behere, P.G.; Mohd Afzal; Kumar, Arun; Biswas, D.J.

2015-01-01

A single mode pulsed fiber laser was used to remove fixed contamination from stainless steel substrate by ablation. Samples were simulated by electro-deposition technique with 232 U as the test contaminant. Laser power, repetition rate, laser beam scanning speed and number of passes were optimised to obtain the desired ablation depth in the substrate. Ablation depth varying between few microns to few hundreds of microns could be achieved through careful control of these processing parameters. The absence of any activity in laser treated samples provided experimental signature of the efficacy of the laser assisted removal of fixed contamination. (author)

Comparison of Vitek Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Versus Conventional Methods in Candida Identification.

Science.gov (United States)

Keçeli, Sema Aşkın; Dündar, Devrim; Tamer, Gülden Sönmez

2016-02-01

Candida species are generally identified by conventional methods such as germ tube or morphological appearance on corn meal agar, biochemical methods using API kits and molecular biological methods. Alternative to these methods, rapid and accurate identification methods of microorganisms called matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDİ-TOF MS) has recently been described. In this study, Candida identification results by API Candida kit, API 20C AUX kit and identifications on corn meal agar (CMA) are compared with the results obtained on Vitek-MS. All results were confirmed by sequencing internal transcribed spacer (ITS) regions of rDNA. Totally, 97 Candida strains were identified by germ tube test, CMA, API and Vitek-MS. Vitek-MS results were compatible with 74.2 % of API 20C AUX and 81.4 % of CMA results. The difference between the results of API Candida and API 20C AUX was detected. The ratio of discrepancy between Vitek-MS and API 20C AUX was 25.8 %. Candida species mostly identified as C. famata or C. tropicalis by and not compatible with API kits were identified as C. albicans by Vitek-MS. Sixteen Candida species having discrepant results with Vitek-MS, API or CMA were randomly chosen, and ITS sequence analysis was performed. The results of sequencing were compatible 56.2 % with API 20C AUX, 50 % with CMA and 93.7 % with Vitek-MS. When compared with conventional identification methods, MS results are more reliable and rapid for Candida identification. MS system may be used as routine identification method in clinical microbiology laboratories.

Direct identification of pathogens from positive blood cultures using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry.

Science.gov (United States)

Rodríguez-Sánchez, B; Sánchez-Carrillo, C; Ruiz, A; Marín, M; Cercenado, E; Rodríguez-Créixems, M; Bouza, E

2014-07-01

In recent years, matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has proved a rapid and reliable method for the identification of bacteria and yeasts that have already been isolated. The objective of this study was to evaluate this technology as a routine method for the identification of microorganisms directly from blood culture bottles (BCBs), before isolation, in a large collection of samples. For this purpose, 1000 positive BCBs containing 1085 microorganisms have been analysed by conventional phenotypic methods and by MALDI-TOF MS. Discrepancies have been resolved using molecular methods: the amplification and sequencing of the 16S rRNA gene or the Superoxide Dismutase gene (sodA) for streptococcal isolates. MALDI-TOF predicted a species- or genus-level identification of 81.4% of the analysed microorganisms. The analysis by episode yielded a complete identification of 814 out of 1000 analysed episodes (81.4%). MALDI-TOF identification is available for clinicians within hours of a working shift, as oppose to 18 h later when conventional identification methods are performed. Moreover, although further improvement of sample preparation for polymicrobial BCBs is required, the identification of more than one pathogen in the same BCB provides a valuable indication of unexpected pathogens when their presence may remain undetected in Gram staining. Implementation of MALDI-TOF identification directly from the BCB provides a rapid and reliable identification of the causal pathogen within hours. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

A survey of useful salt additives in matrix-assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry of lipids: introducing nitrates for improved analysis.

Science.gov (United States)

Griffiths, Rian L; Bunch, Josephine

2012-07-15

Matrix-assisted laser desorption/ionization (MALDI) is a powerful technique for the direct analysis of lipids in complex mixtures and thin tissue sections, making it an extremely attractive method for profiling lipids in health and disease. Lipids are readily detected as [M+H](+), [M+Na](+) and [M+K](+) ions in positive ion MALDI mass spectrometry (MS) experiments. This not only decreases sensitivity, but can also lead to overlapping m/z values of the various adducts of different lipids. Additives can be used to promote formation of a particular adduct, improving sensitivity, reducing spectral complexity and enhancing structural characterization in collision-induced dissociation (CID) experiments. Li(+), Na(+), K(+), Cs(+) and NH(4)(+) cations were considered as a range of salt types (acetates, chlorides and nitrates) incorporated into DHB matrix solutions at concentrations between 5 and 80 mM. The study was extended to evaluate the effect of these additives on CID experiments of a lipid standard, after optimization of collision energy parameters. Experiments were performed on a hybrid quadrupole time-of-flight (QqTOF) instrument. The systematic evaluation of new and existing additives in MALDI-MS and MS/MS of lipids demonstrated the importance of additive cation and anion choice and concentration for tailoring spectral results. The recommended choice of additive depends on the desired outcomes of the experiment to be performed (MS or MS/MS). Nitrates are found to be particularly useful additives for lipid analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Sliding wear resistance of metal matrix composite layers prepared by high power laser

NARCIS (Netherlands)

Ocelik, Vaclav; Matthews, D; de Hosson, Jeff

2005-01-01

Two laser surface engineering techniques, Laser Cladding and Laser Melt Injection (LMI), were used to prepare three different metal matrix composite layers with a thickness of about 1 mm and approximately 25-30% volume fraction of ceramic particles. SiC/Al-8Si, WC/Ti-6Al-4V and TiB2/Ti-6Al-4V layers

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.

Application of laser assisted cold spraying process for metal deposition

CSIR Research Space (South Africa)

Tlotleng, Monnamme

2014-02-01

Full Text Available Laser assisted cold spraying (LACS) process is a hybrid technique that uses laser and cold spray to deposit solid powders on metal substrates. For bonding to occur, the particle velocities must be supersonic which are achieved by entraining...

Matrix-assisted laser desorption/ionization time-of-flight and nano-electrospray ionization ion trap mass spectrometric characterization of 1-cyano-2-substituted-benz[f]isoindole derivatives of peptides for fluorescence detection

DEFF Research Database (Denmark)

Linnemayr, K; Brückner, A; Körner, R

1999-01-01

A series of hexa- to decapeptides (molecular mass range 800-1200) were labeled with naphthalene-2,3-dicarboxaldehyde, which preferentially reacts with the primary amino groups of a peptide. A highly stable peptide conjugate is formed, which allows selective analysis by fluorescence at excitation...... and emission wavelengths of 420 and 490 nm, respectively. After removal of unreacted compounds, the peptide conjugates were characterized by matrix-assisted laser desorption/ionization (MALDI) time-of-flight and nano-electrospray ionization (ESI) ion trap mass spectrometry. They readily form both [M + H]+ ions...... by MALDI and both [M + H]+ and [M + 2H]2+ ions by ESI. Furthermore, the fragmentation behavior of the N-terminally tagged peptides, exhibiting an uncharged N-terminus, was investigated applying post-source decay fragmentation with a curved field reflector and collision-induced dissociation...

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.

A microwave-mediated saponification of galactosylceramide and galactosylceramide I3-sulfate and identification of their lyso-compounds by delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

Taketomi, T; Hara, A; Uemura, K; Kurahashi, H; Sugiyama, E

1996-07-16

Small amounts of galactosylceramide (cerebroside) and galactosylceramide I3-sulfate (sulfatide) obtained from porcine spinal cord and equine kidney were deacylated by a rapid method of microwave-mediated saponification to prepare their lyso-compounds. Mass spectra of their protonated or deprotonated molecular ion peaks were detected by recently developed new technology of a delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometer with reflector detector in positive or negative ion mode. Long chain bases of lysocerebroside and lysosulfatide were different between porcine spinal cord and equine kidney, but similar to each other in the same organ, suggesting their common synthetic pathway. It is noted that the new rapid method can be similarly applied to the deacylation of both cerebroside and sulfatide in contrast to our classical method which was able to be applied to cerebroside, but not to sulfatide.

Recent advances in femtosecond laser-assisted cataract surgery

Directory of Open Access Journals (Sweden)

Zhao-Jie Chu

2013-07-01

Full Text Available Perfect vision and fewer complications is our goal in cataract surgery, femtosecond laser-assisted cataract surgery hold the promise. Applications of femtosecond laser technology for capsulotomy, nuclear fragmentation and corneal incision in cataract surgery bring a new level of accuracy, reproducibility and predictability over the current cataract surgery. The femtosecond laser produces capsulotomies that are more precise, accurate, reproducible, and stronger than those created with the conventional manual technique, and further helps maintain proper positioning of the IOL. Femtosecond laser in nuclear fragmentation lead to a lower effective phacoemulsification time, and the corneal incision is more stable. But currently there are some complications and a clear learning curve associated with the use of femtosecond lasers for cataract surgery. The long-term safety and visual outcomes still need further investigation.

Fractional CO(2) laser-assisted drug delivery

DEFF Research Database (Denmark)

Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A

2010-01-01

Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

International Nuclear Information System (INIS)

Shaji, S.; Garcia, L.V.; Loredo, S.L.; Krishnan, B.

2017-01-01

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb_2S_3) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb_2S_3 thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb_2S_3 thin films for optoelectronic applications.

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Garcia, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Loredo, S.L. [Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, PIIT, Apodaca, Nuevo León (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); and others

2017-01-30

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb{sub 2}S{sub 3}) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb{sub 2}S{sub 3} thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb{sub 2}S{sub 3} thin films for optoelectronic applications.

Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

Science.gov (United States)

Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

2015-12-01

The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

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.

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

Applications of copolymer for rapid identification of bacteria in blood culture broths using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

Ashizawa, Kazuho; Murata, Syota; Terada, Takashi; Ito, Daisuke; Bunya, Masaru; Watanabe, Koji; Teruuchi, Yoko; Tsuchida, Sachio; Satoh, Mamoru; Nishimura, Motoi; Matsushita, Kazuyuki; Sugama, Yuji; Nomura, Fumio

2017-08-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) can be used to identify pathogens in blood culture samples. However, sample pretreatment is needed for direct identification of microbes in blood culture bottles. Conventional protocols are complex and time-consuming. Therefore, in this study, we developed a method for collecting bacteria using polyallylamine-polystyrene copolymer for application in wastewater treatment technology. Using representative bacterial species Escherichia coli and Staphylococcus capitis, we found that polyallylamine-polystyrene can form visible aggregates with bacteria, which can be identified using MALDI-TOF MS. The processing time of our protocol was as short as 15min. Hemoglobin interference in MALDI spectra analysis was significantly decreased in our method compared with the conventional method. In a preliminary experiment, we evaluated the use of our protocol to identify clinical isolates from blood culture bottles. MALDI-TOF MS-based identification of 17 strains from five bacterial species (E. coli, Klebsiella pneumoniae, Enterococcus faecalis, S. aureus, and S. capitis) collected by our protocol was satisfactory. Prospective large-scale studies are needed to further evaluate the clinical application of this novel and simple method of collecting bacteria in blood culture bottles. Copyright © 2017 Elsevier B.V. All rights reserved.

Making Molecular Balloons in Laser-Induced Explosive Boiling of Polymer Solutions

International Nuclear Information System (INIS)

Leveugle, Elodie; Sellinger, Aaron; Fitz-Gerald, James M.; Zhigilei, Leonid V.

2007-01-01

The effect of the dynamic molecular rearrangements leading to compositional segregation is revealed in coarse-grained molecular dynamics simulations of short pulse laser interaction with a polymer solution in a volatile matrix. An internal release of matrix vapor at the onset of the explosive boiling of the overheated liquid is capable of pushing polymer molecules to the outskirts of a transient bubble, forming a polymer-rich surface layer enclosing the volatile matrix material. The results explain unexpected 'deflated balloon' structures observed in films deposited by the matrix-assisted pulsed laser evaporation technique

High performance organic distributed Bragg reflector lasers fabricated by dot matrix holography.

Science.gov (United States)

Wan, Wenqiang; Huang, Wenbin; Pu, Donglin; Qiao, Wen; Ye, Yan; Wei, Guojun; Fang, Zongbao; Zhou, Xiaohong; Chen, Linsen

2015-12-14

We report distributed Bragg reflector (DBR) polymer lasers fabricated using dot matrix holography. Pairs of distributed Bragg reflector mirrors with variable mirror separations are fabricated and a novel energy transfer blend consisting of a blue-emitting conjugated polymer and a red-emitting one is spin-coated onto the patterned substrate to complete the device. Under optical pumping, the device emits sing-mode lasing around 622 nm with a bandwidth of 0.41 nm. The working threshold is as low as 13.5 μJ/cm² (~1.68 kW/cm²) and the measured slope efficiency reaches 5.2%. The distributed feedback (DFB) cavity and the DBR cavity resonate at the same lasing wavelength while the DFB laser shows a much higher threshold. We further show that flexible DBR lasers can be conveniently fabricated through the UV-imprinting technique by using the patterned silica substrate as the mold. Dot matrix holography represents a versatile approach to control the number, the size, the location and the orientation of DBR mirrors, thus providing great flexibility in designing DBR lasers.

Species Identification and Delineation of Pathogenic Mucorales by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

Science.gov (United States)

Shao, Jin; Wan, Zhe; Li, Ruoyu; Yu, Jin

2018-04-01

This study aimed to validate the effectiveness of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based identification of filamentous fungi of the order Mucorales. A total of 111 isolates covering six genera preserved at the Research Center for Medical Mycology of Peking University were selected for MALDI-TOF MS analysis. We emphasized the study of 23 strains of Mucor irregularis predominantly isolated from patients in China. We first used the Bruker Filamentous Fungi library (v1.0) to identify all 111 isolates. To increase the identification rate, we created a compensatory in-house database, the Beijing Medical University (BMU) database, using 13 reference strains covering 6 species, including M. irregularis , Mucor hiemalis , Mucor racemosus , Cunninghamella bertholletiae , Cunninghamella phaeospora , and Cunninghamella echinulata All 111 isolates were then identified by MALDI-TOF MS using a combination of the Bruker library and BMU database. MALDI-TOF MS identified 55 (49.5%) and 74 (66.7%) isolates at the species and genus levels, respectively, using the Bruker Filamentous Fungi library v1.0 alone. A combination of the Bruker library and BMU database allowed MALDI-TOF MS to identify 90 (81.1%) and 111 (100%) isolates at the species and genus levels, respectively, with a significantly increased accuracy rate. MALDI-TOF MS poorly identified Mucorales when the Bruker library was used alone due to its lack of some fungal species. In contrast, this technique perfectly identified M. irregularis after main spectrum profiles (MSPs) of relevant reference strains were added to the Bruker library. With an expanded Bruker library, MALDI-TOF MS is an effective tool for the identification of pathogenic Mucorales. Copyright © 2018 American Society for Microbiology.

Convergence of anatomy, technology, and therapeutics: a review of laser-assisted drug delivers.

Science.gov (United States)

Brauer, Jeremy A; Krakowski, Andrew C; Bloom, Bradley S; Nguyen, Tuyet A; Geronemus, Roy G

2014-12-01

This is a very exciting time in cutaneous laser surgery with an ever-expanding therapeutic armamentarium and an increased sophistication of available technology. These recent trends have allowed for both a rapid development of interest and exploration of laser-assisted drug delivery and its potential applications. We review the current literature on anatomy, technology, and therapeutics as it relates to laser-assisted drug delivery. The focus of our review is on two areas of interest that have received much attention to date - photodynamic therapy in the treatment of actinic keratoses and nonmelanoma skin cancers as well as the treatment of scarring. We will also discuss potential complications of existing modalities used independently and in laser-assisted drug delivery and conclude with future indications for this burgeoning therapeutic methodology.

Journal of Biosciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Heparin-binding proteins (HBPs) are essential constituents of human seminal fluid, which bind to sperm lipids containing the phosphorylcholine group and mediate the fertilization process. We utilized a proteomic set-up consisting of affinity chromatography, isoelectric focusing (IEF) coupled with matrix-assisted laser ...

Comparison of the external physical damages between laser-assisted and mechanical immobilized human sperm using scanning electronic microscopy.

Directory of Open Access Journals (Sweden)

David Y L Chan

Full Text Available We aim to visualize the external physical damages and distinct external phenotypic effects between mechanical and laser-assisted immobilized human spermatozoa using scanning electronic microscopy (SEM. Human spermatozoa were immobilized mechanically or with laser assistance for SEM examination and the membrane integrities were checked on both types of immobilized spermatozoa. We found evidence of external damages at SEM level on mechanically kinked sperm, but not on laser-assisted immobilized sperm. Although no external damage was found on laser-assist immobilized sperm, there were two distinct types of morphological changes when spermatozoa were stricken by infra-red laser. Coiled tails were immediately formed when Laser pulse was applied to the sperm end piece area, whereas laser applied to the sperm principal piece area resulted in a sharp bend of sperm tails. Sperm immobilized by laser did not exhibit any morphological change if the laser did not hit within the on-screen central target zone or if the laser hit the sperm mid piece or head. Our modified membrane integrity assay revealed that the external membrane of more than half of the laser-assisted immobilized sperm remained intact. In conclusion, mechanical immobilization produced membrane damages whilst laser-assisted immobilization did not result in any external membrane damages besides morphological changes at SEM level.

Direct identification of bacteria from charcoal-containing blood culture bottles using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

Science.gov (United States)

Wüppenhorst, N; Consoir, C; Lörch, D; Schneider, C

2012-10-01

Several protocols for direct matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) from positive blood cultures are currently used to speed up the diagnostic process of bacteraemia. Identification rates are high and results are accurate for the BACTEC™ system and for charcoal-free bottles. Only a few studies have evaluated protocols for charcoal-containing BacT/ALERT bottles reaching substantially lower identification rates. We established a new protocol for sample preparation from aerobic and anaerobic positive charcoal-containing BacT/ALERT blood culture bottles and measured the protein profiles (n = 167). Then, we integrated this protocol in the routine workflow of our laboratory (n = 212). During the establishment of our protocol, 74.3 % of bacteria were correctly identified to the species level, in 23.4 %, no result and in 2.4 %, a false identification were obtained. Reliable criteria for correct species identification were a score value ≥1.400 and a best match on rank 1-3 of the same species. Identification rates during routine workflow were 77.8 % for correct identification, 20.8 % for not identified samples and 1.4 % for discordant identification. In conclusion, our results indicate that MALDI-TOF MS is possible, even from charcoal-containing blood cultures. Reliable criteria for correct species identification are a score value ≥1.400 and a best match on rank 1-3 of a single species.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for fast and accurate identification of clinically relevant Aspergillus species.

Science.gov (United States)

Alanio, A; Beretti, J-L; Dauphin, B; Mellado, E; Quesne, G; Lacroix, C; Amara, A; Berche, P; Nassif, X; Bougnoux, M-E

2011-05-01

New Aspergillus species have recently been described with the use of multilocus sequencing in refractory cases of invasive aspergillosis. The classical phenotypic identification methods routinely used in clinical laboratories failed to identify them adequately. Some of these Aspergillus species have specific patterns of susceptibility to antifungal agents, and misidentification may lead to inappropriate therapy. We developed a matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)-based strategy to adequately identify Aspergillus species to the species level. A database including the reference spectra of 28 clinically relevant species from seven Aspergillus sections (five common and 23 unusual species) was engineered. The profiles of young and mature colonies were analysed for each reference strain, and species-specific spectral fingerprints were identified. The performance of the database was then tested on 124 clinical and 16 environmental isolates previously characterized by partial sequencing of the β-tubulin and calmodulin genes. One hundred and thirty-eight isolates of 140 (98.6%) were correctly identified. Two atypical isolates could not be identified, but no isolate was misidentified (specificity: 100%). The database, including species-specific spectral fingerprints of young and mature colonies of the reference strains, allowed identification regardless of the maturity of the clinical isolate. These results indicate that MALDI-TOF MS is a powerful tool for rapid and accurate identification of both common and unusual species of Aspergillus. It can give better results than morphological identification in clinical laboratories. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Protein secondary structure and stability determined by combining exoproteolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Villanueva, Josep; Villegas, Virtudes; Querol, Enrique; Avilés, Francesc X; Serrano, Luis

2002-09-01

In the post-genomic era, several projects focused on the massive experimental resolution of the three-dimensional structures of all the proteins of different organisms have been initiated. Simultaneously, significant progress has been made in the ab initio prediction of protein three-dimensional structure. One of the keys to the success of such a prediction is the use of local information (i.e. secondary structure). Here we describe a new limited proteolysis methodology, based on the use of unspecific exoproteases coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), to map quickly secondary structure elements of a protein from both ends, the N- and C-termini. We show that the proteolytic patterns (mass spectra series) obtained can be interpreted in the light of the conformation and local stability of the analyzed proteins, a direct correlation being observed between the predicted and the experimentally derived protein secondary structure. Further, this methodology can be easily applied to check rapidly the folding state of a protein and characterize mutational effects on protein conformation and stability. Moreover, given global stability information, this methodology allows one to locate the protein regions of increased or decreased conformational stability. All of this can be done with a small fraction of the amount of protein required by most of the other methods for conformational analysis. Thus limited exoproteolysis, together with MALDI-TOF MS, can be a useful tool to achieve quickly the elucidation of protein structure and stability. Copyright 2002 John Wiley & Sons, Ltd.

Identification of bacteria in blood culture broths using matrix-assisted laser desorption-ionization Sepsityper™ and time of flight mass spectrometry.

Science.gov (United States)

Kok, Jen; Thomas, Lee C; Olma, Thomas; Chen, Sharon C A; Iredell, Jonathan R

2011-01-01

Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a novel method for the direct identification of bacteria from blood culture broths. We evaluate for the first time, the performance of the MALDI Sepsityper™ Kit and MS for the identification of bacteria compared to standard phenotypic methods using the manufacturer's specified bacterial identification criteria (spectral scores ≥1.700-1.999 and ≥2.000 indicated identification to genus and species level, respectively). Five hundred and seven positive blood culture broths were prospectively examined, of which 379 (74.8%; 358 monomicrobial, 21 polymicrobial) were identified by MALDI-TOF MS; 195 (100%) and 132 (67.7%) of 195 gram-positive; and 163 (100%) and 149 (91.4%) of 163 gram-negative organisms from monomicrobial blood cultures were correctly identified to genus and species level, respectively. Spectral scores blood culture broths, including 31.6% and 32.3% of gram-positive and polymicrobial blood cultures, respectively. Significantly more gram-negative organisms were identified compared to gram-positive organisms at species level (pblood cultures were misidentified, but at species level only; including four monomicrobial blood cultures with Streptococcus oralis/mitis that were misidentified as Streptococcus pneumoniae. Positive predictive values for the direct identification of both gram-positive and gram-negative bacteria from monomicrobial blood culture broths to genus level were 100%. A diagnostic algorithm for positive blood culture broths that incorporates gram staining and MALDI-TOF MS should identify the majority of pathogens, particularly to genus level.

Analysis of a wavelength selectable cascaded DFB laser based on the transfer matrix method

International Nuclear Information System (INIS)

Xie Hongyun; Chen Liang; Shen Pei; Sun Botao; Wang Renqing; Xiao Ying; You Yunxia; Zhang Wanrong

2010-01-01

A novel cascaded DFB laser, which consists of two serial gratings to provide selectable wavelengths, is presented and analyzed by the transfer matrix method. In this method, efficient facet reflectivity is derived from the transfer matrix built for each serial section and is then used to simulate the performance of the novel cascaded DFB laser through self-consistently solving the gain equation, the coupled wave equation and the current continuity equations. The simulations prove the feasibility of this kind of wavelength selectable laser and a corresponding designed device with two selectable wavelengths of 1.51 μm and 1.53 μm is realized by experiments on InP-based multiple quantum well structure. (semiconductor devices)

Titanium Matrix Composite Ti/TiN Produced by Diode Laser Gas Nitriding

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Aleksander Lisiecki

2015-01-01

Full Text Available A high power direct diode laser, emitting in the range of near infrared radiation at wavelength 808–940 nm, was applied to produce a titanium matrix composite on a surface layer of titanium alloy Ti6Al4V by laser surface gas nitriding. The nitrided surface layers were produced as single stringer beads at different heat inputs, different scanning speeds, and different powers of laser beam. The influence of laser nitriding parameters on the quality, shape, and morphology of the surface layers was investigated. It was found that the nitrided surface layers consist of titanium nitride precipitations mainly in the form of dendrites embedded in the titanium alloy matrix. The titanium nitrides are produced as a result of the reaction between molten Ti and gaseous nitrogen. Solidification and subsequent growth of the TiN dendrites takes place to a large extent at the interface of the molten Ti and the nitrogen gas atmosphere. The direction of TiN dendrites growth is perpendicular to the surface of molten Ti. The roughness of the surface layers depends strongly on the heat input of laser nitriding and can be precisely controlled. In spite of high microhardness up to 2400 HV0.2, the surface layers are crack free.

Damage analysis of fiber reinforced resin matrix composites irradiated by CW laser

International Nuclear Information System (INIS)

Wan Hong; Hu Kaiwei; Mu Jingyang; Bai Shuxin

2008-01-01

In this paper, the damage modes of the carbon fiber and the glass fiber reinforced epoxy or bakelite resin matrix composites irradiated by CW laser under different power densities were analyzed, and the changes of the microstructure and the tensile strength of the composites were also researched. When the resin matrix composites were radiated at a power density more than 0.1 kW/cm 2 , the matrix would be decomposed and the tensile properties of the radiated samples were lost over 30% while the carbon fiber hardly damaged and the glass fiber melted. When the power density of the laser was raised to 1 kW/cm 2 , the matrix burned violently and the carbon fiber cloth began to split with some carbon fiber being fractured, therefore, the fracture strength of the radiated sample lost over 80%. The higher the power density of radiation was, the more serious the damage of the sample was. It was also found that the difference of the matrixes had little effect on the damage extent of the composites. The influence of the radiation density on the temperature of the radiated surface of the carbon/resin composite was numerically calculated by ANSYS finite element software and the calculation results coincided with the damage mode of the radiated composites. (authors)

Standardization of phytopharmaceuticals: qualitative evaluation and quantification of carbohydrates in medicinal plants using tlc, matrix free meldi-tof-ms and gc-ms

International Nuclear Information System (INIS)

Qureshi, M.N.; Bonn, G.K.

2014-01-01

Pharmaceutical industry requires reliable and less time consuming procedures for the quality control analysis of raw materials and finished products. The study was focused on thin layer chromatography (TLC), gas chromatography (GC) and matrix free material enhanced laser desorption ionization time of flight mass spectrometry (mf-MELDI-MS). Standards and microwave assisted water extracts from Achillea milleffolium (herb), Althaea officinalis (roots), Equisetum arvense (herb), Juglans regia (leaves), Matricaria chamomella (flowers) and Taraxacum officinale (herb) were the samples used for this study. The presence of mono- (fructose and glucose) and disaccharide (sucrose) in all the plants under study was proved through the TLC analysis. These results were confirmed by the Mf-MELDI-MS experiments. Gas chromatography coupled to mass spectrometry (GC-MS) confirmed the data obtained via TLC and mf-MELDI-MS, delivering additionally quantified values, but needed a long time. A carbohydrate of higher oligomerization degree could not be found. Among the six plants, glucose was found in highest concentration in Taraxacum officinale. Fructose is present in appreciable quantity in Matricaria chamomella while Althaea officinalis has the highest amount of sucrose among the plants under study. (author)

Influencing Factors and Workpiece's Microstructure in Laser-Assisted Milling of Titanium

Science.gov (United States)

Wiedenmann, R.; Liebl, S.; Zaeh, M. F.

Today's lightweight components have to withstand increasing mechanical and thermal loads. Therefore, advanced materials substitute conventional materials like steel or aluminum alloys. Using these high-performance materials the associated costs become prohibitively high. This paper presents the newest fundamental investigations on the hybrid process 'laser-assisted milling' which is an innovative technique to process such materials. The focus is on the validation of a numerical database for a CAD/CAM process control unit which is calculated by using simulation. Prior to that, the influencing factors on a laser-assisted milling process are systematically investigated using Design of Experiments (DoE) to identify the main influencing parameters coming from the laser and the milling operation.

Applications of interface controlled pulsed-laser deposited polymer films in field-effect transistors

Science.gov (United States)

Adil, Danish; Ukah, Ndubuisi; Guha, Suchi; Gupta, Ram; Ghosh, Kartik

2010-03-01

Matrix assisted pulsed laser evaporation, a derivative of pulsed laser deposition (PLD), is an alternative method of depositing polymer and biomaterial films that allows homogeneous film coverage of high molecular weight organic materials for layer-by-layer growth without any laser induced damage. Polyfluorene (PF)-based conjugated polymers have attracted considerable attention in organic field-effect transistors (FETs). A co-polymer of PF (PFB) was deposited as a thin film using matrix assisted PLD employing a KrF excimer laser. Electrical characteristics of FETs fabricated using these PLD grown films were compared to those of FETs using spin-coated films. We show that threshold voltages, on/off ratios, and charge carrier motilities are significantly improved in PLD grown films. This is attributed to an improved dielectric-polymer interface.

Laser-assisted lip repositioning surgery: Novel approach to treat gummy smile

Directory of Open Access Journals (Sweden)

Sana Farista

2017-01-01

Full Text Available Excessive gingival display (EGD resulting in a “gummy smile” is a major esthetic concern with ramifications in an individual's personal and social life. Numerous treatment modalities have been used for the correction of EGD. The present case report describes the successful treatment of a young woman with an excess gingival display caused by a hyperactive upper lip and a mild vertical maxillary excess that was treated with a laser-assisted lip repositioning surgical technique accompanied by gingival recontouring. The procedure was accomplished by laser-assisted removal, through scraping a strip of mucosa from the maxillary buccal vestibule and suturing the mucosa of the lip to the mucogingival junction. This technique resulted in shortened vestibule and restricted the muscle pull of the elevator muscles of the lip, thereby reducing gingival display when the patient smiles. Laser-assisted lip repositioning surgery can be a viable, minimally invasive alternative to orthognathic surgery.

Matrix-assisted laser desorption-ionization mass spectrometry peptide mass fingerprinting for proteome analysis: identification efficiency after on-blot or in-gel digestion with and without desalting procedures.

Science.gov (United States)

Lamer, S; Jungblut, P R

2001-03-10

In theory, peptide mass fingerprinting by matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS) has the potential to identify all of the proteins detected by silver staining on gels. In practice, if the genome of the organism investigated is completely sequenced, using current techniques, all proteins stained by Coomassie Brilliant Blue can be identified. This loss of identification sensitivity of ten to hundred-fold is caused by loss of peptides by surface contacts. Therefore, we performed digestion and transfer of peptides in the lower microl range and reduced the number of steps. The peptide mix obtained from in-gel or on-blot digestion was analyzed directly after digestion or after concentration on POROS R2 beads. Eight protein spots of a 2-DE gel from Mycobacterium bovis BCG were identified using these four preparation procedures for MALDI-MS. Overall, on-blot digestion was as effective as in-gel digestion. Whereas higher signal intensities resulted after concentration, hydrophilic peptides are better detected by direct measurement of the peptide mix without POROS R2 concentration.

Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in comparison to rpoB gene sequencing for species identification of bloodstream infection staphylococcal isolates.

Science.gov (United States)

Spanu, T; De Carolis, E; Fiori, B; Sanguinetti, M; D'Inzeo, T; Fadda, G; Posteraro, B

2011-01-01

As a result of variable expression of biochemical characters, misidentification by conventional phenotypic means often occurs with clinical isolates belonging to Staphylococcus species. Therefore, we evaluated the use of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of 450 blood isolates of the most relevant staphylococcal species, using sequence analysis of the rpoB gene as the reference method. A correct species identification by MALDI-TOF was obtained in 99.3% (447/450), with only three isolates being misidentified. In addition, MALDI-TOF correctly identified all the staphylococcal subspecies studied, including Staphylococcus capitis subsp. capitis and subsp. urealyticus, Staphylococcus cohnii subsp. urealyticus, Staphylococcus hominis subsp. novobiosepticus and subsp. hominis, Staphylococcus saprophyticus subsp. saprophyticus, Staphylococcus schleiferi subsp. schleiferi and Staphylococcus sciuri subsp. sciuri. Thus, MALDI-TOF MS-based species identification of staphylococci can be routinely achieved without any substantial costs for consumables or the time needed for labour-intensive DNA sequence analysis. © 2010 The Authors. Journal Compilation © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Rapid method for direct identification of bacteria in urine and blood culture samples by matrix-assisted laser desorption ionization time-of-flight mass spectrometry: intact cell vs. extraction method.

Science.gov (United States)

Ferreira, L; Sánchez-Juanes, F; Muñoz-Bellido, J L; González-Buitrago, J M

2011-07-01

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is a fast and reliable technology for the identification of microorganisms with proteomics approaches. Here, we compare an intact cell method and a protein extraction method before application on the MALDI plate for the direct identification of microorganisms in both urine and blood culture samples from clinical microbiology laboratories. The results show that the intact cell method provides excellent results for urine and is a good initial method for blood cultures. The extraction method complements the intact cell method, improving microorganism identification from blood culture. Thus, we consider that MALDI-TOF MS performed directly on urine and blood culture samples, with the protocols that we propose, is a suitable technique for microorganism identification, as compared with the routine methods used in the clinical microbiology laboratory. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

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...

Laser assisted embedding of nanoparticles into metallic materials

International Nuclear Information System (INIS)

Lin Dong; Suslov, Sergey; Ye Chang; Liao Yiliang; Liu, C. Richard; Cheng, Gary J.

2012-01-01

This paper reports a methodology of half-embedding nanoparticles into metallic materials. Transparent and opaque nanoparticles are chosen to demonstrate the process of laser assisted nanoparticle embedding. Dip coating method is used to coat transparent or opaque nanoparticle on the surface of metallic material. Nanoparticles are embedded into substrate by laser irradiation. In this study, the mechanism and process of nanoparticle embedding are investigated. It is found both transparent and opaque nanoparticles embedding are with high densities and good uniformities.

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.

Microstructure-sensitive flow stress modeling for force prediction in laser assisted milling of Inconel 718

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Pan Zhipeng

2017-01-01

Full Text Available Inconel 718 is a typical hard-to-machine material that requires thermally enhanced machining technology such as laser-assisted milling. Based upon finite element analysis, this study simulates the forces in the laser-assisted milling process of Inconel 718 considering the effects of grain growth due to γ' and γ" phases. The γ" phase is unstable and becomes the δ phase, which is likely to precipitate at a temperature over 750 °C. The temperature around the center of spot in the experiments is 850 °C, so the phase transformation and grain growth happen throughout the milling process. In the analysis, this study includes the microstructure evolution while accounting for the effects of dynamic recrystallization and grain growth through the Avrami model. The grain growth reduces the yield stress and flow stress, which improves the machinability. In finite element analysis (FEA, several boundary conditions of temperature varying with time are defined to simulate the movement of laser spot, and the constitutive model is described by Johnson-Cook equation. In experiments, this study collects three sets of cutting forces and finds that the predicted values are in close agreements with measurements especially in feed direction, in which the smallest error is around 5%. In another three simulations, this study also examines the effect of laser preheating on the cutting forces by comparison with a traditional milling process without laser assist. When the laser is off, the forces increase in all cases, which prove the softening effect of laser-assisted milling. In addition, when the axial depth of milling increases, the laser has a more significant influence, especially in axial direction, in which the force with laser is more than 18% smaller than the one without laser. Overall, this study validates the influence of laser-assisted milling on Inconel 718 by predicting the cutting forces in FEA.

Characteristics of laser assisted machining for silicon nitride ceramic according to machining parameters

International Nuclear Information System (INIS)

Kim, Jong Do; Lee, Su Jin; Suh, Jeong

2011-01-01

This paper describes the Laser Assisted Machining (LAM) that cuts and removes softened parts by locally heating the ceramic with laser. Silicon nitride ceramics can be machined with general machining tools as well, because YSiAlON, which was made up ceramics, is soften at about 1,000 .deg. C. In particular, the laser, which concentrates on highly dense energy, can locally heat materials and very effectively control the temperature of the heated part of specimen. Therefore, this paper intends to propose an efficient machining method of ceramic by deducing the machining governing factors of laser assisted machining and understanding its mechanism. While laser power is the machining factor that controls the temperature, the CBN cutting tool could cut the material more easily as the material gets deteriorated from the temperature increase by increasing the laser power, but excessive oxidation can negatively affect the quality of the material surface after machining. As the feed rate and cutting depth increase, the cutting force increases and tool lifespan decreases, but surface oxidation also decreases. In this experiment, the material can be cut to 3 mm of cutting depth. And based on the results of the experiment, the laser assisted machining mechanism is clarified

Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography-tandem mass spectrometry.

Science.gov (United States)

Giacinti, Géraldine; Raynaud, Christine; Capblancq, Sophie; Simon, Valérie

2017-02-03

The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS 2 ) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV-vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg -1 , whereas these compounds were not detected in the flesh extracts (<0.05mgkg -1 ). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS 2 . The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts. Copyright © 2016 Elsevier B.V. All rights reserved.

A simple method for rapid microbial identification from positive monomicrobial blood culture bottles through matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

Lin, Jung-Fu; Ge, Mao-Cheng; Liu, Tsui-Ping; Chang, Shih-Cheng; Lu, Jang-Jih

2017-06-30

Rapid identification of microbes in the bloodstream is crucial in managing septicemia because of its high disease severity, and direct identification from positive blood culture bottles through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) can shorten the turnaround time. Therefore, we developed a simple method for rapid microbiological identification from positive blood cultures by using MALDI-TOF MS. We modified previously developed methods to propose a faster, simpler and more economical method, which includes centrifugation and hemolysis. Specifically, our method comprises two-stage centrifugation with gravitational acceleration (g) at 600g and 3000g, followed by the addition of a lysis buffer and another 3000g centrifugation. In total, 324 monomicrobial bacterial cultures were identified. The success rate of species identification was 81.8%, which is comparable with other complex methods. The identification success rate was the highest for Gram-negative aerobes (85%), followed by Gram-positive aerobes (78.2%) and anaerobes (67%). The proposed method requires less than 10 min, costs less than US$0.2 per usage, and facilitates batch processing. We conclude that this method is feasible for clinical use in microbiology laboratories, and can serve as a reference for treatments or further complementary diagnostic testing. Copyright © 2017. Published by Elsevier B.V.

Laser-assisted deposition of thin C60 films

DEFF Research Database (Denmark)

Schou, Jørgen; Canulescu, Stela; Fæster, Søren

Metal and metal oxide films with controlled thickness from a fraction of a monolayer up more than 1000 nm and known stoichiometry can be produced by pulsed laser deposition (PLD) relatively easily, and (PLD) is now a standard technique in all major research laboratories within materials science...... of the matrix material, anisole, with a concentration of 0.67 wt% C60. At laser fluences below 1.5 J/cm2, a dominant fraction of the film molecules are C60 transferred to the substrate without any fragmentation. High-resolution SEM images of MAPLE deposited films reveal large circular features on the surface...

Effect of laser power and scanning speed on laser deposited Ti6Al4V/TiB2 matrix composites

CSIR Research Space (South Africa)

Mokgalaka, MN

2012-10-01

Full Text Available Additive Manufacturing in Industry Conference, Kwa Maritane, Pilanesberg National Park, 31 October-2 November 2012 EFFECT OF LASER POWER AND SCANNING SPEED ON LASER DEPOSITED Ti6Al4V/TiB2 MATRIX COMPOSITES M.N. Mokgalaka2,1, S.L. Pityana1,2, A.P.I...

Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

DEFF Research Database (Denmark)

Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya

2009-01-01

The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for estab...

Speciation of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry†

Science.gov (United States)

Mandrell, Robert E.; Harden, Leslie A.; Bates, Anna; Miller, William G.; Haddon, William F.; Fagerquist, Clifton K.

2005-01-01

Multiple strains of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis isolated from animal, clinical, or food samples have been analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Whole bacterial cells were harvested from colonies or confluent growth on agar and transferred directly into solvent and then to a spot of dried 3-methoxy-4-hydroxycinnamic acid (matrix). Multiple ions in the 5,000- to 15,000-Da mass range were evident in spectra for each strain; one or two ions in the 9,500- to 11,000-Da range were consistently high intensity. “Species-identifying” biomarker ions (SIBIs) were evident from analyses of multiple reference strains for each of the six species, including the genome strains C. jejuni NCTC 11168 and C. jejuni RM1221. Strains grown on nine different combinations of media and atmospheres yielded SIBI masses within ±5 Da with external instrument calibration. The highest-intensity C. jejuni SIBIs were cytosolic proteins, including GroES, HU/HCj, and RplL. Multiple intraspecies SIBIs, corresponding probably to nonsynonymous nucleotide polymorphisms, also provided some intraspecies strain differentiation. MALDI-TOF MS analysis of 75 additional Campylobacter strains isolated from humans, poultry, swine, dogs, and cats revealed (i) associations of SIBI type with source, (ii) strains previously speciated incorrectly, and (iii) “strains” composed of more than one species. MALDI-TOF MS provides an accurate, sensitive, and rapid method for identification of multiple Campylobacter species relevant to public health and food safety. PMID:16204551

Speciation of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Mandrell, Robert E; Harden, Leslie A; Bates, Anna; Miller, William G; Haddon, William F; Fagerquist, Clifton K

2005-10-01

Multiple strains of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis isolated from animal, clinical, or food samples have been analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Whole bacterial cells were harvested from colonies or confluent growth on agar and transferred directly into solvent and then to a spot of dried 3-methoxy-4-hydroxycinnamic acid (matrix). Multiple ions in the 5,000- to 15,000-Da mass range were evident in spectra for each strain; one or two ions in the 9,500- to 11,000-Da range were consistently high intensity. "Species-identifying" biomarker ions (SIBIs) were evident from analyses of multiple reference strains for each of the six species, including the genome strains C. jejuni NCTC 11168 and C. jejuni RM1221. Strains grown on nine different combinations of media and atmospheres yielded SIBI masses within +/-5 Da with external instrument calibration. The highest-intensity C. jejuni SIBIs were cytosolic proteins, including GroES, HU/HCj, and RplL. Multiple intraspecies SIBIs, corresponding probably to nonsynonymous nucleotide polymorphisms, also provided some intraspecies strain differentiation. MALDI-TOF MS analysis of 75 additional Campylobacter strains isolated from humans, poultry, swine, dogs, and cats revealed (i) associations of SIBI type with source, (ii) strains previously speciated incorrectly, and (iii) "strains" composed of more than one species. MALDI-TOF MS provides an accurate, sensitive, and rapid method for identification of multiple Campylobacter species relevant to public health and food safety.

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.

Rapid identification of bacteria from positive blood culture bottles by use of matrix-assisted laser desorption-ionization time of flight mass spectrometry fingerprinting.

Science.gov (United States)

Christner, Martin; Rohde, Holger; Wolters, Manuel; Sobottka, Ingo; Wegscheider, Karl; Aepfelbacher, Martin

2010-05-01

Early and adequate antimicrobial therapy has been shown to improve the clinical outcome in bloodstream infections (BSI). To provide rapid pathogen identification for targeted treatment, we applied matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectrometry fingerprinting to bacteria directly recovered from blood culture bottles. A total of 304 aerobic and anaerobic blood cultures, reported positive by a Bactec 9240 system, were subjected in parallel to differential centrifugation with subsequent mass spectrometry fingerprinting and reference identification using established microbiological methods. A representative spectrum of bloodstream pathogens was recovered from 277 samples that grew a single bacterial isolate. Species identification by direct mass spectrometry fingerprinting matched reference identification in 95% of these samples and worked equally well for aerobic and anaerobic culture bottles. Application of commonly used score cutoffs to classify the fingerprinting results led to an identification rate of 87%. Mismatching mostly resulted from insufficient bacterial numbers and preferentially occurred with Gram-positive samples. The respective spectra showed low concordance to database references and were effectively rejected by score thresholds. Spiking experiments and examination of the respective study samples even suggested applicability of the method to mixed cultures. With turnaround times around 100 min, the approach allowed for reliable pathogen identification at the day of blood culture positivity, providing treatment-relevant information within the critical phase of septic illness.

Microstructure and wear resistance of a laser clad TiC reinforced nickel aluminides matrix composite coating

International Nuclear Information System (INIS)

Chen, Y.; Wang, H.M.

2004-01-01

Wear resistant TiC/(NiAl-Ni 3 Al) composite coating was fabricated on a substrate of electrolyzed nickel by laser cladding using Ni-Al-Ti-C alloy powders. The laser clad coating is metallurgically bonded to the substrate and has a homogenous fine microstructure consisting of the flower-like equiaxed TiC dendrite and the dual phase matrix of NiAl and Ni 3 Al. The intermetallic matrix composite coating exhibits excellent wear resistance under both room- and high-temperature sliding wear test conditions due to the high hardness of TiC coupled with the strong atomic bonds of intermetallic matrix

CdS thin films prepared by laser assisted chemical bath deposition

International Nuclear Information System (INIS)

Garcia, L.V.; Mendivil, M.I.; Garcia Guillen, G.; Aguilar Martinez, J.A.; Krishnan, B.; Avellaneda, D.; Castillo, G.A.; Das Roy, T.K.; Shaji, S.

2015-01-01

Highlights: • CdS thin films by conventional CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • Improved dark conductivity and good photocurrent response for the LACBD CdS. - Abstract: In this work, we report the preparation and characterization of CdS thin films by laser assisted chemical bath deposition (LACBD). CdS thin films were prepared from a chemical bath containing cadmium chloride, triethanolamine, ammonium hydroxide and thiourea under various deposition conditions. The thin films were deposited by in situ irradiation of the bath using a continuous laser of wavelength 532 nm, varying the power density. The thin films obtained during deposition of 10, 20 and 30 min were analyzed. The changes in morphology, structure, composition, optical and electrical properties of the CdS thin films due to in situ irradiation of the bath were analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The thin films obtained by LACBD were nanocrystalline, photoconductive and presented interesting morphologies. The results showed that LACBD is an effective synthesis technique to obtain nanocrystalline CdS thin films having good optoelectronic properties

CdS thin films prepared by laser assisted chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Garcia, L.V.; Mendivil, M.I.; Garcia Guillen, G.; Aguilar Martinez, J.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); CIIDIT – Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Avellaneda, D.; Castillo, G.A.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); CIIDIT – Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

2015-05-01

Highlights: • CdS thin films by conventional CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • Improved dark conductivity and good photocurrent response for the LACBD CdS. - Abstract: In this work, we report the preparation and characterization of CdS thin films by laser assisted chemical bath deposition (LACBD). CdS thin films were prepared from a chemical bath containing cadmium chloride, triethanolamine, ammonium hydroxide and thiourea under various deposition conditions. The thin films were deposited by in situ irradiation of the bath using a continuous laser of wavelength 532 nm, varying the power density. The thin films obtained during deposition of 10, 20 and 30 min were analyzed. The changes in morphology, structure, composition, optical and electrical properties of the CdS thin films due to in situ irradiation of the bath were analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The thin films obtained by LACBD were nanocrystalline, photoconductive and presented interesting morphologies. The results showed that LACBD is an effective synthesis technique to obtain nanocrystalline CdS thin films having good optoelectronic properties.

Fingerprinting of egg and oil binders in painted artworks by matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of lipid oxidation by-products.

Science.gov (United States)

Calvano, C D; van der Werf, I D; Palmisano, F; Sabbatini, L

2011-06-01

A matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based approach was applied for the detection of various lipid classes, such as triacylglycerols (TAGs) and phospholipids (PLs), and their oxidation by-products in extracts of small (50-100 μg) samples obtained from painted artworks. Ageing of test specimens under various conditions, including the presence of different pigments, was preliminarily investigated. During ageing, the TAGs and PLs content decreased, whereas the amount of diglycerides, short-chain oxidative products arising from TAGs and PLs, and oxidized TAGs and PLs components increased. The examination of a series of model paint samples gave a clear indication that specific ions produced by oxidative cleavage of PLs and/or TAGs may be used as markers for egg and drying oil-based binders. Their elemental composition and hypothetical structure are also tentatively proposed. Moreover, the simultaneous presence of egg and oil binders can be easily and unambiguously ascertained through the simultaneous occurrence of the relevant specific markers. The potential of the proposed approach was demonstrated for the first time by the analysis of real samples from a polyptych of Bartolomeo Vivarini (fifteenth century) and a "French school" canvas painting (seventeenth century).

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

Identification of bacteria in blood culture broths using matrix-assisted laser desorption-ionization Sepsityper™ and time of flight mass spectrometry.

Directory of Open Access Journals (Sweden)

Jen Kok

Full Text Available Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS is a novel method for the direct identification of bacteria from blood culture broths. We evaluate for the first time, the performance of the MALDI Sepsityper™ Kit and MS for the identification of bacteria compared to standard phenotypic methods using the manufacturer's specified bacterial identification criteria (spectral scores ≥1.700-1.999 and ≥2.000 indicated identification to genus and species level, respectively. Five hundred and seven positive blood culture broths were prospectively examined, of which 379 (74.8%; 358 monomicrobial, 21 polymicrobial were identified by MALDI-TOF MS; 195 (100% and 132 (67.7% of 195 gram-positive; and 163 (100% and 149 (91.4% of 163 gram-negative organisms from monomicrobial blood cultures were correctly identified to genus and species level, respectively. Spectral scores <1.700 (no identification were obtained in 128/507 (25.2% positive blood culture broths, including 31.6% and 32.3% of gram-positive and polymicrobial blood cultures, respectively. Significantly more gram-negative organisms were identified compared to gram-positive organisms at species level (p<0.0001. Five blood cultures were misidentified, but at species level only; including four monomicrobial blood cultures with Streptococcus oralis/mitis that were misidentified as Streptococcus pneumoniae. Positive predictive values for the direct identification of both gram-positive and gram-negative bacteria from monomicrobial blood culture broths to genus level were 100%. A diagnostic algorithm for positive blood culture broths that incorporates gram staining and MALDI-TOF MS should identify the majority of pathogens, particularly to genus level.

Laser-assisted cartilage reshaping: in vitro and in vivo animal studies

Science.gov (United States)

Wang, Zhi; Pankratov, Michail M.; Perrault, Donald F., Jr.; Shapshay, Stanley M.

1995-05-01

Correction of cartilaginous defects in the head and neck area remains a challenge for the surgeon. This study investigated a new technique for laser-assisted cartilage reshaping. The pulsed 1.44 micrometers Nd:YAG laser was used in vitro and in vivo experiments to irradiate cartilage to change it's shape without carbonization or vaporization of tissue. Two watts of average power in non contact manner was used to irradiate and reshape the cartilage. The extracted reshaped cartilage specimens underwent testing of elastic force with a computer assisted measurement system that recorded the changes in elastic force in the specimens from 1 hr to 11 days post-irradiation. An animal model of defective tracheal cartilage (collapsed tracheal wall) was created, allowed to heal for 6 weeks and then corrected endoscopically with the laser-assisted technique. The results of the in vitro and in vivo investigations demonstrated that it was possible to alter the cartilage and that cartilage would retain its new shape. The clinical significance of the technique is evident and warrants further animal studies and clinical trials.

Genetic, phenotypic and matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based identification of anaerobic bacteria and determination of their antimicrobial susceptibility at a University Hospital in Japan.

Science.gov (United States)

Yunoki, Tomoyuki; Matsumura, Yasufumi; Nakano, Satoshi; Kato, Karin; Hotta, Go; Noguchi, Taro; Yamamoto, Masaki; Nagao, Miki; Takakura, Shunji; Ichiyama, Satoshi

2016-05-01

The accuracies of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and the phenotypic method using VITEK 2 were compared to the accuracy of 16S rRNA sequence analysis for the identification of 170 clinically isolated anaerobes. The antimicrobial susceptibility of the isolates was also evaluated. Genetic analysis identified 21 Gram-positive species in 14 genera and 29 Gram-negative species in 11 genera. The most frequently isolated genera were Prevotella spp. (n = 46), Bacteroides spp. (n = 25) and Clostridium spp. (n = 25). MALDI-TOF MS correctly identified more isolates compared with VITEK 2 at the species (80 vs. 58%, respectively; p anaerobic agents indicated that the isolates of the three most frequently identified anaerobic genera exhibited good antimicrobial susceptibility. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Study on the effect of thermal property of metals in ultrasonic-assisted laser machining

International Nuclear Information System (INIS)

Lee, Hu Seung; Kim, Gun Woo; Park, Jong Eun; Cho, Sung Hak; Yang, Min Yang; Park, Jong Kweon

2015-01-01

The laser machining process has been proposed as an advanced process for the selective fabrication of electrodes without a mask. In this study, we adapt laser machining to metals that have different thermal properties. Based on the results, the metals exhibit a different surface morphology, heat-affected zone (HAZ), and a recast layer around the machined surface according to their thermal conductivity, boiling point, and thermal diffusivity. Then, we apply ultrasonic-assisted laser machining to remove the recast layer. The ultrasonic-assisted laser machining exhibits a better surface quality in metals with higher diffusivity than those having lower diffusivity

Matrix influences on the determination of common ions by using ion chromatography part 1--determination of inorganic anions.

Science.gov (United States)

Michalski, Rajmund; Lyko, Aleksandra; Kurzyca, Iwona

2012-07-01

Ion chromatography is the most popular instrumental analytical method used for the determination of anions and cations in water and wastewater. Isocratic ion chromatography with suppressed conductivity detection is frequently used in laboratories carrying out routine analyses of inorganic anions. The paper presents the results of the research into the influence of selected inorganic anions dominant in environmental samples (Cl(-), NO(3)(-), SO(4)(2-)) on the possibility of simultaneous determination of F(-), Cl(-), NO(2)(-), NO(3)(-), PO(4)(3-) and SO(4)(2-) with the application of this most popular ion chromatography type in standard separation conditions. Four Dionex and four Metrohm anion-exchange columns were tested in standard separation conditions recommended by their manufacturers with both standard solutions and environmental samples with complex matrix.

Laser assisted decontamination of nuclear fuel elements

International Nuclear Information System (INIS)

Padma Nilaya, J.; Biswas, Dhruba J.; Kumar, Aniruddha

2010-04-01

Laser assisted removal of loosely bound fuel particulates from the clad surface following the process of pellet loading has decided advantages over conventional methods. It is a dry and noncontact process that generates very little secondary waste and can occur inside a glove box without any manual interference minimizing the possibility of exposure to personnel. The rapid rise of the substrate/ particulate temperature owing to the absorption of energy from the incident laser pulse results in a variety of processes that may lead to the expulsion of the particulates. As a precursor to the cleaning of the fuel elements, initial experiments were carried out on contamination simulated on commonly used clad surfaces to gain a first hand experience on the various laser parameters for which as efficient cleaning can be obtained without altering the properties of the clad surface. The cleaning of a dummy fuel element was subsequently achieved in the laboratory by integrating the laser with a work station that imparted simultaneous rotational and linear motion to the fuel element. (author)

Unusual analyte-matrix adduct ions and mechanism of their formation in MALDI TOF MS of benzene-1,3,5-tricarboxamide and urea compounds

NARCIS (Netherlands)

Lou, X.; Fransen, M.; Stals, P.J.M.; Mes, T.; Bovee, R.; Dongen, van J.L.J.; Meijer, E.W.

2013-01-01

Analyte-matrix adducts are normally absent under typical matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) conditions. Interestingly, though, in the analysis of several types of organic compounds synthesized in our laboratory, analyte-matrix adduct ion peaks

Direct bacterial identification from positive blood cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry: A systematic review and meta-analysis.

Science.gov (United States)

Ruiz-Aragón, Jesús; Ballestero-Téllez, Mónica; Gutiérrez-Gutiérrez, Belén; de Cueto, Marina; Rodríguez-Baño, Jesús; Pascual, Álvaro

2017-10-27

The rapid identification of bacteraemia-causing pathogens could assist clinicians in the timely prescription of targeted therapy, thereby reducing the morbidity and mortality of this infection. In recent years, numerous techniques that rapidly and directly identify positive blood cultures have been marketed, with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) being one of the most commonly used. The aim of this systematic review and meta-analysis was to evaluate the accuracy of MALDI-TOF (Bruker ® ) for the direct identification of positive blood culture bottles. A meta-analysis was performed to summarize the results of the 32 studies evaluated. The overall quality of the studies was moderate. For Gram-positive bacteria, overall rates of correct identification of the species ranged from 0.17 to 0.98, with a cumulative rate (random-effects model) of 0.72 (95% CI: 0.64-0.80). For Gram-negative bacteria, correct identification rates ranged from 0.66 to 1.00, with a cumulative effect of 0.92 (95% CI: 0.88-0.95). For Enterobacteriaceae, the rate was 0.96 (95% CI: 0.94-0.97). MALDI-TOF mass spectrometry shows high accuracy for the correct identification of Gram-negative bacteria, particularly Enterobacteriaceae, directly from positive blood culture bottles, and moderate accuracy for the identification of Gram-positive bacteria (low for some species). Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Design of a femtosecond laser assisted tomographic atom probe

International Nuclear Information System (INIS)

Gault, B.; Vurpillot, F.; Vella, A.; Gilbert, M.; Menand, A.; Blavette, D.; Deconihout, B.

2006-01-01

A tomographic atom probe (TAP) in which the atoms are field evaporated by means of femtosecond laser pulses has been designed. It is shown that the field evaporation is assisted by the laser field enhanced by the subwavelength dimensions of the specimen without any significant heating of the specimen. In addition, as compared with the conventional TAP, due to the very short duration of laser pulses, no spread in the energy of emitted ions is observed, leading to a very high mass resolution in a straight TAP in a wide angle configuration. At last, laser pulses can be used to bring the intense electric field required for the field evaporation on poor conductive materials such as intrinsic Si at low temperature. In this article, the performance of the laser TAP is described and illustrated through the investigation of metals, oxides, and silicon materials

The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source.

Science.gov (United States)

Venkatesan, K

2017-07-01

Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60-150 m/min, feed rates of 0.05-0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

UV laser-assisted fabrication of ridge waveguides in lithium niobate crystals

OpenAIRE

Sones, C.L.; Ying, C.Y.J.; Eason, R.W.; Mailis, S.; Ganguly, P.; Soergel, E.

2010-01-01

We present a UV laser-assisted method for the fabrication of ridge waveguides in lithium niobate. The UV laser irradiation step provides the refractive index change required for the vertical light confinement in the waveguide and also defines the ferroelectric domain pattern which produces the ridge structures after chemical etching.

Matrix effect in analysis of pesticide residues in fruits and vegetables by high performance liquid chromatography with quadrupole-time of flight mass spectrometry

Directory of Open Access Journals (Sweden)

Andoralov A.M.

2017-03-01

Full Text Available For modern food safety control are using techniques that allow to determinate a large number of components. So for determination of pesticide residues in fruits and vegetables commonly used methods of gas and liquid chromatography with time-of-flight mass-spectrometric detection. This system allows to carry out quantitative determination several hundreds of pesticides and their identification by the characteristic fragments of the mass spectrum. The main problem when using mass spectrometric detection is a matrix effect, which is caused by the influence of matrix components extracted with pesticides from the sample. In this work, attempts have been made to reduce the influence of the matrix in the analysis of pesticide residues by high performance liquid chromatography with time of flight mass spectrometry (HPLC / TOFMS.

Screening of Chlamydomonas reinhardtii Populations with Single-Cell Resolution by Using a High-Throughput Microscale Sample Preparation for Matrix-Assisted Laser Desorption Ionization Mass Spectrometry.

Science.gov (United States)

Krismer, Jasmin; Sobek, Jens; Steinhoff, Robert F; Fagerer, Stephan R; Pabst, Martin; Zenobi, Renato

2015-08-15

The consequences of cellular heterogeneity, such as biocide persistence, can only be tackled by studying each individual in a cell population. Fluorescent tags provide tools for the high-throughput analysis of genomes, RNA transcripts, or proteins on the single-cell level. However, the analysis of lower-molecular-weight compounds that elude tagging is still a great challenge. Here, we describe a novel high-throughput microscale sample preparation technique for single cells that allows a mass spectrum to be obtained for each individual cell within a microbial population. The approach presented includes spotting Chlamydomonas reinhardtii cells, using a noncontact microarrayer, onto a specialized slide and controlled lysis of cells separated on the slide. Throughout the sample preparation, analytes were traced and individual steps optimized using autofluorescence detection of chlorophyll. The lysates of isolated cells are subjected to a direct, label-free analysis using matrix-assisted laser desorption ionization mass spectrometry. Thus, we were able to differentiate individual cells of two Chlamydomonas reinhardtii strains based on single-cell mass spectra. Furthermore, we showed that only population profiles with real single-cell resolution render a nondistorted picture of the phenotypes contained in a population. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Structural characterization of native high-methoxylated pectin using nuclear magnetic resonance spectroscopy and ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Comparative use of 2,5-dihydroxybenzoic acid and nor-harmane as UV-MALDI matrices.

Science.gov (United States)

Monge, María Eugenia; Negri, R Martín; Kolender, Adriana A; Erra-Balsells, Rosa

2007-01-01

The successful analysis by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) of native and hydrolyzed high-methoxylated pectin samples is described. In order to find the optimal conditions for UV-MALDI-TOF MS analysis several experimental variables were studied such as: different UV-MALDI matrices (nor-harmane, 2,5-dihydroxybenzoic acid), sample preparation methods (mixture, sandwich), inorganic salt addition (doping salts, NaCl, KCl, NH(4)Cl), ion mode (positive, negative), linear and reflectron mode, etc. nor-Harmane has never been used as a UV-MALDI matrix for the analysis of pectins but its use avoids pre-treatment of the sample, such as an enzymatic digestion or an acid hydrolysis, and there is no need to add salts, making the analysis easier and faster. This study suggested an alternative way of analyzing native high-methoxylated pectins, with UV-MALDI-TOF MS, by using nor-harmane as the matrix in negative ion mode. The analysis by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy of the native and hydrolyzed pectin is also briefly described. Copyright (c) 2007 John Wiley & Sons, Ltd.

Laser-assisted fibrinogen bonding of umbilical vein grafts.

Science.gov (United States)

Oz, M C; Williams, M R; Souza, J E; Dardik, H; Treat, M R; Bass, L S; Nowygrod, R

1993-06-01

Despite success with autologous tissue welding, laser welding of synthetic vascular prostheses has not been possible. The graft material appears inert and fails to allow the collagen breakdown and electrostatic bonding that results in tissue welding. To develop a laser welding system for graft material, we repaired glutaraldehyde-tanned human umbilical cord vein graft incisions using laser-assisted fibrinogen bonding (LAFB) technology. Modified umbilical vein graft was incised transversely (1.2 cm). Incisions were repaired using sutures, laser energy alone, or LAFB. For LAFB, indocyanine green dye was mixed with human fibrinogen and the compound applied with forceps onto the weld site prior to exposure to 808 nm diode laser energy (power density 4.8 W/cm 2). Bursting pressures for sutured repairs (126.6 +/- 23.4 mm Hg) were similar to LAFB anastomoses (111.6 +/- 55.0 mm Hg). No evidence of collateral thermal injury to the graft material was noted. In vivo evaluation of umbilical graft bonding with canine arteries demonstrates that LAFB can reliably reinforce sutured anastomoses. The described system for bonding graft material with laser exposed fibrinogen may allow creation or reinforcement of vascular anastomoses in procedures where use of autologous tissue is not feasible.

Effects of laser-assisted lipolysis on nipple-areola complex.

Science.gov (United States)

Sönmez Ergün, Selma; Kayan, Reşit Burak; Güleş, Mustafa Ekrem; Kuzu, İsmail Melih

2017-08-01

Gynecomastia, as a most common benign condition, represents itself as the enlargement of the male breast and also nipple-areola complex as the severity of the condition increases. With this study, we aimed to clarify the effects of 980-nm diode laser on nipple-areola complex (NAC). Although numerous open techniques have been described to correct gynecomastia, nowadays trends have shifted to minimally invasive techniques such as laser-assisted lipolysis (LAL). A total of 25 patients with bilateral gynecomastia treated with LAL by using a 980-nm diode laser. The resultant contour and reduced size of the complex were satisfactory. LAL leads to significant reduction of the size of NAC.

Biological function evaluation and effects of laser micro-pore burn-denatured acellular dermal matrix.

Science.gov (United States)

Zhang, Youlai; Zeng, Yuanlin; Xin, Guohua; Zou, Lijin; Ding, Yuewei; Duyin, Jiang

2018-03-01

In the field of burns repairs, many problems exist in the shortage of donor skin, the expense of allograft or xenograft skin, temporary substitution and unsatisfactory extremity function after wound healing. Previous studies showed that burn-denatured skin could return to normal dermis formation and function. This study investigates the application of laser micro-pore burn-denatured acellular dermis matrix (DADM) from an escharotomy in the repair of burn wounds and evaluates the biological properties and wound repair effects of DADM in implantation experiments in Kunming mice. Specific-pathogen-free (SPF) Kunming mice were used in this study. A deep II° burn wound was created on the dorsum of the mice by an electric heated water bath. The full-thickness wound tissue was harvested. The necrotic tissue and subcutaneous tissue were removed. The denatured dermis was preserved and treated with 0.25% trypsin, 0.5% Triton X-100. The DADM was drilled by laser micro-pore. The biological properties and grafting effects of laser micro-pore burn-DADM were evaluated by morphology, cytokine expression levels and subcutaneous implantation experiments in Kunming mice. We found statistical significance (Ppore burn-DADM (experimental group) compared to the control group (no laser micro-pore burn-DADM). Cytokine expression level was different in the dermal matrixes harvested at various time points after burn (24h, 48h, 72h and infected wound group). Comparing the dermal matrix from 24h burn tissue to infected wound tissue, the expression level of IL-6, MMP-24, VE-cadherin and VEGF were decreased. We found no inflammatory cells infiltration in the dermal matrix were observed in both experimental and control groups (24h burn group), while the obviously vascular infiltration and fiber fusion were observed in the experimental group after subcutaneous implantation experiments. There was better bio-performance, low immunogenicity and better dermal incorporation after treated by laser

One-year follow-up of femtosecond laser-assisted penetrating keratoplasty

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Tan JCH

2013-02-01

Full Text Available Johnson Choon-Hwai Tan, Wee-Jin HengNational Healthcare Group Eye Institute, Tan Tock Seng Hospital, SingaporeBackground: The purpose of this report is to describe the initial outcomes of femtosecond laser-assisted penetrating keratoplasty.Methods: This retrospective surgical case series consisted of 10 eyes from 10 patients undergoing penetrating keratoplasty at a tertiary center. Femtosecond laser was used to perform a zig-square incision on the donor cornea with matched dimensions on the recipient cornea. Outcomes measured included: unaided visual acuity and best spectacle-corrected visual acuity preoperatively and at one, 3, 6, and 12 months postoperatively; manifest refractive and topographic astigmatism at 3, 6, and 12 months postoperatively; and endothelial cell density loss, calculated at the end of the one-year follow-up period.Results: At one-year follow-up, there was an improvement in unaided visual acuity from a mean preoperative logMAR of 1.67 to 0.44, and best spectacle-corrected visual acuity from a mean preoperative logMAR of 1.33 to 0.13. By postoperative month 3, mean manifest refractive and topographic astigmatism was 2.31 ± 1.41 D and 2.59 ± 1.57 D, respectively. The mean reduction in endothelial cell density was 20.7% after one year of follow-up.Conclusion: Femtosecond laser-assisted penetrating keratoplasty provided a good visual outcome and early visual rehabilitation due to precise graft-host alignment and reduced astigmatism in the early postoperative months.Keywords: penetrating keratoplasty, femtosecond laser-assisted keratoplasty

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

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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.

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

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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.

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

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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.

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.

The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source

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K. Venkatesan

2017-07-01

Full Text Available Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60–150 m/min, feed rates of 0.05–0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

Hydroxylapatite chromatography.

Science.gov (United States)

Broadhurst, A V

2001-05-01

Hydroxylapatite (also called hydroxyapatite), a form of calcium phosphate, can be used as a matrix for the chromatography of both proteins and nucleic acids. Protocols are provided for both standard low-pressure chromatography of a protein mixture using a hydroxylapatite column prepared in the laboratory, and an HPLC method, applicable to proteins and nucleic acids, that uses a commercially available column. Alternate protocols describe column chromatography using a step gradient or batch binding and step-gradient elution.

Nanoparticle assisted laser desorption/ionization mass spectrometry for small molecule analytes.

Science.gov (United States)

Abdelhamid, Hani Nasser

2018-03-01

Nanoparticle assisted laser desorption/ionization mass spectrometry (NPs-ALDI-MS) shows remarkable characteristics and has a promising future in terms of real sample analysis. The incorporation of NPs can advance several methods including surface assisted LDI-MS, and surface enhanced LDI-MS. These methods have advanced the detection of many thermally labile and nonvolatile biomolecules. Nanoparticles circumvent the drawbacks of conventional organic matrices for the analysis of small molecules. In most cases, NPs offer a clear background without interfering peaks, absence of fragmentation of thermally labile molecules, and allow the ionization of species with weak noncovalent interactions. Furthermore, an enhancement in sensitivity and selectivity can be achieved. NPs enable straightforward analysis of target species in a complex sample. This review (with 239 refs.) covers the progress made in laser-based mass spectrometry in combination with the use of metallic NPs (such as AuNPs, AgNPs, PtNPs, and PdNPs), NPs consisting of oxides and chalcogenides, silicon-based NPs, carbon-based nanomaterials, quantum dots, and metal-organic frameworks. Graphical abstract An overview is given on nanomaterials for use in surface-assisted laser desorption/ionization mass spectrometry of small molecules.

Laser-assisted fixation of a nitinol stapes prosthesis.

Science.gov (United States)

Schrötzlmair, Florian; Suchan, Fabian; Pongratz, Thomas; Krause, Eike; Müller, Joachim; Sroka, Ronald

2018-02-01

Otosclerosis is an inner ear bone disease characterized by fixation of the stapes and consequently progressive hearing loss. One treatment option is the surgical replacement of the stapes by a prosthesis. When so called "smart materials" like nitinol are used, prosthesis fixation can be performed using a laser without manual crimping on the incus. However, specific laser-prosthesis interactions have not been described yet. The aim of the present study was to elucidate the thermo-mechanical properties of the NiTiBOND® prosthesis as a basis for handling instructions for laser-assisted prosthesis fixation. Closure of the NiTiBOND® prosthesis was induced ex vivo by either a diode laser emitting at λ = 940 nm or a CO 2 laser (λ = 10,600 nm). Total energy for closure was determined. Suitable laser parameters (pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis) were assessed. Specific laser-prosthesis interactions were recorded. Especially the diode laser was found to be an appropriate energy source. A total energy deposit of 60 mJ by pulses in near contact application was found to be sufficient for prosthesis closure ex vivo. Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter. Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account. NiTiBOND® stapes prosthesis can be closed by very little energy when appropriate energy sources like diode lasers are used, suggesting a relatively safe application in vivo. Lasers Surg. Med. 50:153-157, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

International Nuclear Information System (INIS)

Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

2009-01-01

An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained

Multi-scale graphene patterns on arbitrary substrates via laser-assisted transfer-printing process

KAUST Repository

Park, J. B.; Yoo, J.-H.; Grigoropoulos, C. P.

2012-01-01

A laser-assisted transfer-printing process is developed for multi-scale graphene patterns on arbitrary substrates using femtosecond laser scanning on a graphene/metal substrate and transfer techniques without using multi-step patterning processes

Characterisation and quantification of liposome-type nanoparticles in a beverage matrix using hydrodynamic chromatography and MALDI–TOF mass spectrometry

NARCIS (Netherlands)

Helsper, J.P.F.G.; Peters, R.J.B.; Brouwer, L.; Weigel, S.

2013-01-01

This paper describes the characterisation of liposome-type nanoparticles (NPs) dispersed in a beverage matrix. Characterisation is based on a two-step procedure: first, liposomes are separated on the basis of size in the nanometre range by use of hydrodynamic chromatography (HDC); second, chemical

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of molds of the Fusarium genus.

Science.gov (United States)

Triest, David; Stubbe, Dirk; De Cremer, Koen; Piérard, Denis; Normand, Anne-Cécile; Piarroux, Renaud; Detandt, Monique; Hendrickx, Marijke

2015-02-01

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. Copyright © 2015

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

Direct identification of bacteria in positive blood culture bottles by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.

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Bernard La Scola

Full Text Available BACKGROUND: With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. METHODOLOGY/PRINCIPAL FINDINGS: We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66% were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. CONCLUSIONS/SIGNIFICANCE: MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture

Direct identification of bacteria in positive blood culture bottles by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.

Science.gov (United States)

La Scola, Bernard; Raoult, Didier

2009-11-25

With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66%) were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture broths growing viridans streptococci is obtained in the near future.

Cost Savings Realized by Implementation of Routine Microbiological Identification by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

Science.gov (United States)

Tran, Anthony; Alby, Kevin; Kerr, Alan; Jones, Melissa; Gilligan, Peter H

2015-08-01

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is an emerging technology for rapid identification of bacterial and fungal isolates. In comparison to conventional methods, this technology is much less labor intensive and can provide accurate and reliable results in minutes from a single isolated colony. We compared the cost of performing the bioMérieux Vitek MALDI-TOF MS with conventional microbiological methods to determine the amount saved by the laboratory by converting to the new technology. Identification costs for 21,930 isolates collected between April 1, 2013, and March 31, 2014, were directly compared for MALDI-TOF MS and conventional methodologies. These isolates were composed of commonly isolated organisms, including commonly encountered aerobic and facultative bacteria and yeast but excluding anaerobes and filamentous fungi. Mycobacterium tuberculosis complex and rapidly growing mycobacteria were also evaluated for a 5-month period during the study. Reagent costs and a total cost analysis that included technologist time in addition to reagent expenses and maintenance service agreement costs were analyzed as part of this study. The use of MALDI-TOF MS equated to a net savings of $69,108.61, or 87.8%, in reagent costs annually compared to traditional methods. When total costs are calculated to include technologist time and maintenance costs, traditional identification would have cost $142,532.69, versus $68,886.51 with the MALDI-TOF MS method, resulting in a laboratory savings of $73,646.18, or 51.7%, annually by adopting the new technology. The initial cost of the instrument at our usage level would be offset in about 3 years. MALDI-TOF MS not only represents an innovative technology for the rapid and accurate identification of bacterial and fungal isolates, it also provides a significant cost savings for the laboratory. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The Exploration of Peptide Biomarkers in Malignant Pleural Effusion of Lung Cancer Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

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Jing Xu

2017-01-01

Full Text Available Background. Diagnoses of malignant pleural effusion (MPE are a crucial problem in clinics. In our study, we compared the peptide profiles of MPE and tuberculosis pleural effusion (TPE to investigate the value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS in diagnosis of MPE. Material and Methods. The 46 MPE and 32 TPE were randomly assigned to training set and validation set. Peptides were isolated by weak cation exchange magnetic beads and peaks in the m/z range of 800–10000 Da were analyzed. Comparing the peptide profile between 30 MPE and 22 TPE samples in training set by ClinProTools software, we screened the specific biomarkers and established a MALDI-TOF-MS classification of MPE. Finally, the other 16 MPE and 10 TPE were included to verify the model. We additionally determined carcinoembryonic antigen (CEA in MPE and TPE samples using electrochemiluminescent immunoassay method. Results. Five peptide peaks (917.37 Da, 4469.39 Da, 1466.5 Da, 4585.21 Da, and 3216.87 Da were selected to separate MPE and TPE by MALDI-TOF-MS. The sensitivity, specificity, and accuracy of the classification were 93.75%, 100%, and 96.15%, respectively, after blinded test. The sensitivity of CEA was significantly lower than MALDI-TOF-MS classification (P=0.035. Conclusions. The results indicate MALDI-TOF-MS is a potential method for diagnosing MPE.

An experimental investigation of pulsed laser-assisted machining of AISI 52100 steel

Science.gov (United States)

Panjehpour, Afshin; Soleymani Yazdi, Mohammad R.; Shoja-Razavi, Reza

2014-11-01

Grinding and hard turning are widely used for machining of hardened bearing steel parts. Laser-assisted machining (LAM) has emerged as an efficient alternative to grinding and hard turning for hardened steel parts. In most cases, continuous-wave lasers were used as a heat source to cause localized heating prior to material removal by a cutting tool. In this study, an experimental investigation of pulsed laser-assisted machining of AISI 52100 bearing steel was conducted. The effects of process parameters (i.e., laser mean power, pulse frequency, pulse energy, cutting speed and feed rate) on state variables (i.e., material removal temperature, specific cutting energy, surface roughness, microstructure, tool wear and chip formation) were investigated. At laser mean power of 425 W with frequency of 120 Hz and cutting speed of 70 m/min, the benefit of LAM was shown by 25% decrease in specific cutting energy and 18% improvement in surface roughness, as compared to those of the conventional machining. It was shown that at constant laser power, the increase of laser pulse energy causes the rapid increase in tool wear rate. Pulsed laser allowed efficient control of surface temperature and heat penetration in material removal region. Examination of the machined subsurface microstructure and microhardness profiles showed no change under LAM and conventional machining. Continuous chips with more uniform plastic deformation were produced in LAM.

Reactions of laser ablated uranium with nitrogen studied using matrix isolation spectroscopy

International Nuclear Information System (INIS)

Sankaran, K.; Sundararajan, K.; Viswanathan, K.S.

1999-01-01

Unusual reactions were found to occur when uranium was laser ablated in the presence of nitrogen. The reaction products were trapped in a rigid inert gas matrix and studied using infrared spectroscopy. The species formed were strongly dependent on the partial pressure of nitrogen in the matrix gas used during the ablation process; at low nitrogen partial pressures uranium dinitride (NUN) was the major reaction product, while at high partial pressures of nitrogen the mononitride, UN, was the predominant product. (author)

Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers

DEFF Research Database (Denmark)

Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H. P.

2016-01-01

Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers......, which allows us to extend the measurement bandwidth to 37.4 THz (1355-1630 nm) at megahertz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy, and in particular it enables us to characterize the dispersion...

Solid phase extraction for removal of matrix effects in lipophilic marine toxin analysis by liquid chromatography-tandem mass spectrometry

NARCIS (Netherlands)

Gerssen, A.; McElhinney, M.; Mulder, P.P.J.; Bire, R.; Hess, P.; Boer, de J.

2009-01-01

The potential of solid phase extraction (SPE) clean-up has been assessed to reduce matrix effects (signal suppression or enhancement) in the liquid chromatography-tandem mass spectrometry (LC¿MS/MS) analysis of lipophilic marine toxins. A large array of ion-exchange, silica-based, and mixed-function

Solid phase extraction for removal of matrix effects in lipophilic marine toxin analysis by liquid chromatography-tandem mass spectrometry

NARCIS (Netherlands)

Gerssen, A.; McElhinney, A. M.; Mulder, P.P.J.; Bire, L.; Hess, P.; de Boer, J.

2009-01-01

The potential of solid phase extraction (SPE) clean-up has been assessed to reduce matrix effects (signal suppression or enhancement) in the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of lipophilic marine toxins. A large array of ion-exchange, silica-based, and mixed-function

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.

Profiling the triacylglyceride contents in bat integumentary lipids by preparative thin layer chromatography and MALDI-TOF mass spectrometry.

Science.gov (United States)

Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

2013-09-05

The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals.

Inhibition of enamel demineralisation using "Nd-YAG and diode laser assisted fluoride therapy".

Science.gov (United States)

Chand, B R; Kulkarni, S; Mishra, P

2016-02-01

This in vitro study was to evaluate the irradiation efficacy of the Diode laser and the Nd-YAG laser either un-assisted or assisted by acidulated phosphate fluoride (APF) treatment on enamel's acid resistance. Seventy-two enamel samples, obtained from 12 extracted human molars, were randomly assigned to 6 groups as follows: (1) Control (C); (2) Exposed to APF gel (F); (3) Diode laser (DL); (4) Irradiated with Diode laser through APF gel (DL/F); (5) Nd-YAG laser (NL) and (6) Irradiated with Nd-YAG laser through APF gel (NL/F). The specimens were individually demineralised in an acidified hydroxyethylcellulose system, and the acid resistance was evaluated by determining the calcium ion dissolution using atomic absorption spectrometry. The average concentration of the calcium ion determined in groups 1 to 6 was 901, 757, 736, 592, 497 and 416 parts per million micrograms/gram, respectively. The results showed that demineralisation in the NL/F group was significantly less than the other groups and the control group was significantly greater than the other groups (P laser irradiation, used alone or in combination with APF, in decreasing the enamel demineralisation was greater than all the other groups.

Nanoparticle and nanorod films deposited by matrix assisted pulsed laser evaporation

Science.gov (United States)

Caricato, A. P.; Cesaria, M.; Luches, A.; Martino, M.

2012-07-01

The promising results obtained with the MAPLE-deposition of nanostructured thin films, to be used in different fields, are reviewed. Nanoparticles (TiO2, SnO2, CdS) and nanorods (TiO2) with well defined dimensions were suspended in appropriate solvents (distilled water, toluene) with low concentration (1wt% or less). The solutions were flash frozen at the liquid nitrogen temperature to form the targets to be laser irradiated. The MAPLE process allowed a successful transfer from the target to rough and flat substrates, preserving the starting composition and crystalline phase of the nanostructures in a wide range of experimental conditions. In contrast, a careful choice of the laser fluence is mandatory to avoid shape modifications. Growth of metal nanoparticles with a low dispersion in size was also obtained by the MAPLE technique, starting from target solutions of a metallorganic element (AcPd) diluted in different solvents (acetone, diethyl ether). It seems that selecting the solvent with appropriate values of viscosity and boiling temperatures, it is possible to modulate the nanoparticles size. Most of the deposited nanostructured films were tested as sensing elements for gas sensors.

Systematic evaluation of matrix effects in hydrophilic interaction chromatography versus reversed phase liquid chromatography coupled to mass spectrometry.

Science.gov (United States)

Periat, Aurélie; Kohler, Isabelle; Thomas, Aurélien; Nicoli, Raul; Boccard, Julien; Veuthey, Jean-Luc; Schappler, Julie; Guillarme, Davy

2016-03-25

Reversed phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) is the gold standard technique in bioanalysis. However, hydrophilic interaction chromatography (HILIC) could represent a viable alternative to RPLC for the analysis of polar and/or ionizable compounds, as it often provides higher MS sensitivity and alternative selectivity. Nevertheless, this technique can be also prone to matrix effects (ME). ME are one of the major issues in quantitative LC-MS bioanalysis. To ensure acceptable method performance (i.e., trueness and precision), a careful evaluation and minimization of ME is required. In the present study, the incidence of ME in HILIC-MS/MS and RPLC-MS/MS was compared for plasma and urine samples using two representative sets of 38 pharmaceutical compounds and 40 doping agents, respectively. The optimal generic chromatographic conditions in terms of selectivity with respect to interfering compounds were established in both chromatographic modes by testing three different stationary phases in each mode with different mobile phase pH. A second step involved the assessment of ME in RPLC and HILIC under the best generic conditions, using the post-extraction addition method. Biological samples were prepared using two different sample pre-treatments, i.e., a non-selective sample clean-up procedure (protein precipitation and simple dilution for plasma and urine samples, respectively) and a selective sample preparation, i.e., solid phase extraction for both matrices. The non-selective pretreatments led to significantly less ME in RPLC vs. HILIC conditions regardless of the matrix. On the contrary, HILIC appeared as a valuable alternative to RPLC for plasma and urine samples treated by a selective sample preparation. Indeed, in the case of selective sample preparation, the compounds influenced by ME were different in HILIC and RPLC, and lower and similar ME occurrence was generally observed in RPLC vs. HILIC for urine and plasma samples

Mueller-matrix of laser-induced autofluorescence of polycrystalline films of dried peritoneal fluid in diagnostics of endometriosis

Science.gov (United States)

Ushenko, Yuriy A.; Koval, Galina D.; Ushenko, Alexander G.; Dubolazov, Olexander V.; Ushenko, Vladimir A.; Novakovskaia, Olga Yu.

2016-07-01

This research presents investigation results of the diagnostic efficiency of an azimuthally stable Mueller-matrix method of analysis of laser autofluorescence of polycrystalline films of dried uterine cavity peritoneal fluid. A model of the generalized optical anisotropy of films of dried peritoneal fluid is proposed in order to define the processes of laser autofluorescence. The influence of complex mechanisms of both phase (linear and circular birefringence) and amplitude (linear and circular dichroism) anisotropies is taken into consideration. The interconnections between the azimuthally stable Mueller-matrix elements characterizing laser autofluorescence and different mechanisms of optical anisotropy are determined. The statistical analysis of coordinate distributions of such Mueller-matrix rotation invariants is proposed. Thereupon the quantitative criteria (statistic moments of the first to the fourth order) of differentiation of polycrystalline films of dried peritoneal fluid, group 1 (healthy donors) and group 2 (uterus endometriosis patients), are determined.

The Evaluation of Surface Integrity During Machining of Inconel 718 with Various Laser Assistance Strategies

Directory of Open Access Journals (Sweden)

Wojciechowski Szymon

2017-01-01

Full Text Available The paper is focused on the evaluation of surface integrity formed during turning of Inconel 718 with the application of various laser assistance strategies. The primary objective of the work was to determine the relations between the applied machining strategy and the obtained surface integrity, in order to select the effective cutting conditions allowing the obtainment of high surface quality. The carried out experiment included the machining of Inconel 718 in the conventional turning conditions, as well as during the continuous laser assisted machining and sequential laser assistance. The surface integrity was evaluated by the measurements of machined surface topographies, microstructures and the microhardness. Results revealed that surface integrity of Inconel 718 is strongly affected by the selected machining strategy. The significant improvement of the surface roughness formed during machining of Inconel 718, can be reached by the application of simultaneous laser heating and cutting (LAM.

Matrix effect on emission/current correlated analysis in laser-induced breakdown spectroscopy of liquid droplets

International Nuclear Information System (INIS)

Huang, J.-S.; Ke, C.-B.; Lin, K.-C.

2004-01-01

We have investigated influence of matrix salts on the liquid droplets by laser-induced breakdown spectroscopy (LIBS). An electrospray ionization technique coupled with LIBS is employed to generate the microdroplets of the Na sample solution with various matrix salts added. A sequence of single-shot time-resolved LIB emission signals is detected. The LIB signal intensity integrated within a gate linearly correlates with the plasma-induced current response obtained simultaneously on a single-shot basis. The slopes thus obtained increase with the sample concentration, but appear to be irrespective of different matrix salts, added up to a 2000 mg/l concentration. The matrix salts involved have the same K + cation but different anions. Given a laser radiation emitting at 355 nm with the energy fixed at 23±1 mJ, a limit of detection (LOD) of 1.0 mg/l may be achieved for the Na analysis. The current normalization might have probably taken into account the ablated amount of the sample and the plasma temperature. Accordingly, the LIB/current correlated analysis becomes efficient to suppress the signal fluctuation, improve the LOD determination, and concurrently correct the matrix effect

Imipenem-avibactam: a novel combination for the rapid detection of carbapenemase activity in Enterobacteriaceae and Acinetobacter baumannii by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Oviaño, Marina; Bou, Germán

2017-02-01

In the present study, we propose a novel matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based method for detecting carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii. For this, we analyzed a series of 131 isolates. Among them, a total of 115 Enterobacteriaceae: 79 of them carrying a carbapenemase enzyme (15bla KPC , 7bla NDM , 11bla IMP , 12bla VIM , and 34bla OXA-48 ) and 16 A. baumannii isolates: 15 of them carrying carbapenemases (10bla OXA-23, 2bla OXA-58, 2bla OXA-24 , and 1bla OXA-237 ). The rest of the isolates were noncarbapenemase producers and used as negative controls. The isolates were submitted to susceptibility testing using a combination of imipenem-avibactam and analysis by the MALDI-TOF Biotyper Compass software (Bruker Daltonik, Germany). The assay showed an overall sensitivity and specificity for carbapenemase detection of 98% and 100%, respectively. The combination of imipenem and avibactam displayed activity against KPC and OXA-48-producing Enterobacteriaceae and thus represents a new strategy for identifying and confirming these carbapenemases. However, the combination did not provide any benefit over A. baumannii. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Graphene/TiO2 nanocomposite based solid-phase extraction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for lipidomic profiling of avocado (Persea americana Mill.).

Science.gov (United States)

Shen, Qing; Yang, Mei; Li, Linqiu; Cheung, Hon-Yeung

2014-12-10

Phospholipids possess important physiological, structural and nutritional functions in biological systems. This study described a solid-phase extraction (SPE) method, employing graphene and titanium dioxide (G/TiO2) nanocomposite as sorbent, for the selective isolation and enrichment of phospholipids from avocado (Persea americana Mill.). Based on the principal that the phosphoryl group in the phospholipid can interact with TiO2 via a bridging bidentate mode, an optimum condition was established for SPE, and was successfully applied to prepare avocado samples. The extracts were monitored by matrix-assisted laser desorption ionization time-of-flight/tandem mass spectrometry (MALDI-TOF/MS) in both positive-ion and negative-ion modes. Results showed that phospholipids could be efficiently extracted in a clean manner by G/TiO2 based SPE. In addition, the signals of phospholipids were enhanced while the noise was reduced. Some minor peaks became more obvious. In conclusion, the nanocomposite material of G/TiO2 was proved to be a promising sorbent for selective separation of phospholipids from crude lipid extract. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Laser assisted bioprinting using a femtosecond laser with and without a gold transductive layer: a parametric study

Science.gov (United States)

Desrus, H.; Chassagne, B.; Catros, S.; Artiges, C.; Devillard, R.; Petit, S.; Deloison, F.; Fricain, J. C.; Guillemot, F.; Kling, R.

2016-03-01

Experimental results of femtosecond Laser Assisted Bioprinting (LAB) are reported on. Two set-up, used to print different model bioinks and keratinocytes cells line HaCaT, were studied: first one was using a femtosecond laser with low pulse energy and an absorbing gold layer, whereas the second one used high pulse energy enabling the removal of the absorbing layer. Printed drop diameter and resulting height of the bioink jet are then quantified as a function of the LAB parameters such as laser energy, focus spot location or numerical aperture.

Feasibility of LED-Assisted CMOS Camera: Contrast Estimation for Laser Tattoo Treatment

Directory of Open Access Journals (Sweden)

Ngot Thi Pham

2018-04-01

Full Text Available Understanding the residual tattoo ink in skin after laser treatment is often critical for achieving good clinical outcomes. The current study aims to investigate the feasibility of a light-emitting diode (LED-assisted CMOS camera to estimate the relative variations in tattoo contrast after the laser treatment. Asian mice were tattooed using two color inks (black and red. The LED illumination was a separate process from the laser tattoo treatment. Images of the ink tattoos in skin were acquired under the irradiation of three different LED colors (red, green, and blue for pre- and post-treatment. The degree of contrast variation due to the treatment was calculated and compared with the residual tattoo distribution in the skin. The black tattoo demonstrated that the contrast consistently decreased after the laser treatment for all LED colors. However, the red tattoo showed that the red LED yielded an insignificant contrast whereas the green and blue LEDs induced a 30% (p < 0.001 and 26% (p < 0.01 contrast reduction between the treatment conditions, respectively. The proposed LED-assisted CMOS camera can estimate the relative variations in the image contrast before and after the laser tattoo treatment.

Femtosecond laser refractive surgery: small-incision lenticule extraction vs. femtosecond laser-assisted LASIK.

Science.gov (United States)

Lee, Jimmy K; Chuck, Roy S; Park, Choul Yong

2015-07-01

Small-incision lenticule extraction (SMILE) is a novel technique devised to correct refractive errors. SMILE circumvents excimer laser photoablation of cornea, as the stromal lenticule cut by femtosecond laser is removed manually. Smaller incisions and preservation of anterior corneal biomechanical strength have been suggested as some of the advantages of SMILE over femtosecond laser-assisted LASIK (FS-LASIK). In this review, we compared previous published results of SMILE and FS-LASIK. The advantage, efficacy and safety of SMILE are compared with FS-LASIK. SMILE achieved similar efficacy, predictability and safety as FS-LASIK. Greater preservations of corneal biomechanical strength and corneal nerves were observed in SMILE when compared with LASIK or PRK. Additionally, the incidence of postoperative dry eye syndrome was found to be less problematic in SMILE than in FS-LASIK. SMILE is a promising new surgery for refractive error correction. Prospective and retrospective studies of SMILE have shown that results of SMILE are similar to FS-LASIK. With advances in femtosecond laser technology, SMILE may gain greater acceptance in the future.

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.

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.

Novel, improved sample preparation for rapid, direct identification from positive blood cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

Science.gov (United States)

Schubert, Sören; Weinert, Kirsten; Wagner, Chris; Gunzl, Beatrix; Wieser, Andreas; Maier, Thomas; Kostrzewa, Markus

2011-11-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used for rapid and reliable identification of bacteria and yeast grown on agar plates. Moreover, MALDI-TOF MS also holds promise for bacterial identification from blood culture (BC) broths in hospital laboratories. The most important technical step for the identification of bacteria from positive BCs by MALDI-TOF MS is sample preparation to remove blood cells and host proteins. We present a method for novel, rapid sample preparation using differential lysis of blood cells. We demonstrate the efficacy and ease of use of this sample preparation and subsequent MALDI-TOF MS identification, applying it to a total of 500 aerobic and anaerobic BCs reported to be positive by a Bactec 9240 system. In 86.5% of all BCs, the microorganism species were correctly identified. Moreover, in 18/27 mixed cultures at least one isolate was correctly identified. A novel method that adjusts the score value for MALDI-TOF MS results is proposed, further improving the proportion of correctly identified samples. The results of the present study show that the MALDI-TOF MS-based method allows rapid (directly from positive BCs and with high accuracy. Copyright © 2011 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

Collagen crosslinking for ectasia following PRK performed in excimer laser-assisted keratoplasty for keratoconus.

Science.gov (United States)

Spadea, Leopoldo

2012-01-01

To report the results of corneal collagen crosslinking (CXL) in a patient with corneal ectasia developed after excimer laser-assisted lamellar keratoplasty for keratoconus and a secondary photorefractive keratectomy (PRK) for residual refractive error. A 33-year-old woman, who had originally been treated for keratoconus in the right eye by excimer laser-assisted lamellar keratoplasty, subsequently had her residual ametropia treated by topographically guided, transepithelial excimer laser PRK. Five years after PRK, the patient developed corneal ectasia showing concomitant visual changes of best spectacle-corrected visual acuity (BSCVA) reduced to 20/33 with a refraction of -6.00 +6.00 × 30. The minimum corneal thickness at the ectasia apex was 406 µm. A treatment of riboflavin-UVA-induced corneal CXL was performed on the right eye. Two years after the CXL treatment, the right eye improved to 20/20 BSCVA with a refraction of plano +1.00 × 50 while exhibiting a clear lamellar graft. Corneal CXL provided safe and effective management of ectasia developed after excimer laser-assisted lamellar keratoplasty and PRK.

Stress assisted selective ablation of ITO thin film by picosecond laser

Science.gov (United States)

Farid, Nazar; Chan, Helios; Milne, David; Brunton, Adam; M. O'Connor, Gerard

2018-01-01

Fast selective pattering with high precession on 175 nm ITO thin film with IR ps lasers is investigated. Ablation parameters are optimized with detailed studies on the scribed depth, topography, and particle generation using AFM and SEM. A comparison of 10 and 150 ps laser revealed that the shorter pulse (10 ps) laser is more appropriate in selective and partial ablation; up to 20 nm resolution for controlled depth with multipulses having energy below the damage threshold is demonstrated. The experimental results are interpreted to involve stress assisted ablation mechanism for the 10 ps laser while thermal ablation along with intense melting occurs for 150 ps laser. The transition between these regimes is estimated to occur at approximately 30 ps.

Laser-assisted growth of carbon nanotubes on laser-patterned substrates and inside sealed micro-channels

NARCIS (Netherlands)

Burgt, Y. van de; Bellouard, Y.

2014-01-01

Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition

Examination of the skin barrier repair/wound healing process using a living skin equivalent model and matrix-assisted laser desorption-ionization-mass spectrometry imaging.

Science.gov (United States)

Lewis, E E L; Barrett, M R T; Freeman-Parry, L; Bojar, R A; Clench, M R

2018-04-01

Examination of the skin barrier repair/wound healing process using a living skin equivalent (LSE) model and matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to identify lipids directly involved as potential biomarkers. These biomarkers may be used to determine whether an in vivo wound is going to heal for example if infected. An in vitro LSE model was wounded with a scalpel blade and assessed at day 4 post-wounding by histology and MALDI-MSI. Samples were sectioned at wound site and were either formalin-fixed paraffin-embedded (FFPE) for histology or snapped frozen (FF) for MSI analysis. The combination of using an in vitro wounded skin model with MSI allowed the identification of lipids involved in the skin barrier repair/wound healing process. The technique was able to highlight lipids directly in the wound site and distinguish differences in lipid distribution between the epidermis and wound site. This novel method of coupling an in vitro LSE with MSI allowed in-depth molecular analysis of the skin barrier repair/wound healing process. The technique allowed the identification of lipids directly involved in the skin barrier repair/wound healing process, indicating these biomarkers may be potentially be used within the clinic. These biomarkers will help to determine, which stage of the skin barrier repair/wound healing process the wound is in to provide the best treatment. © 2018 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Effects of solid-medium type on routine identification of bacterial isolates by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Anderson, Neil W; Buchan, Blake W; Riebe, Katherine M; Parsons, Lauren N; Gnacinski, Stacy; Ledeboer, Nathan A

2012-03-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid method for the identification of bacteria. Factors that may alter protein profiles, including growth conditions and presence of exogenous substances, could hinder identification. Bacterial isolates identified by conventional methods were grown on various media and identified using the MALDI Biotyper (Bruker Daltonics, Billerica, MA) using a direct smear method and an acid extraction method. Specimens included 23 Pseudomonas isolates grown on blood agar, Pseudocel (CET), and MacConkey agar (MAC); 20 Staphylococcus isolates grown on blood agar, colistin-nalidixic acid agar (CNA), and mannitol salt agar (MSA); and 25 enteric isolates grown on blood agar, xylose lysine deoxycholate agar (XLD), Hektoen enteric agar (HE), salmonella-shigella agar (SS), and MAC. For Pseudomonas spp., the identification rate to genus using the direct method was 83% from blood, 78% from MAC, and 94% from CET. For Staphylococcus isolates, the identification rate to genus using the direct method was 95% from blood, 75% from CNA, and 95% from MSA. For enteric isolates, the identification rate to genus using the direct method was 100% from blood, 100% from MAC, 100% from XLD, 92% from HE, and 87% from SS. Extraction enhanced identification rates. The direct method of MALDI-TOF analysis of bacteria from selective and differential media yields identifications of varied confidence. Notably, Staphylococci spp. from CNA exhibit low identification rates. Extraction enhances identification rates and is recommended for colonies from this medium.

A report of laser-assisted modified Widman flap for periodontal regeneration: Clinical and radiographic evaluation

Directory of Open Access Journals (Sweden)

Sanjeev Kumar Salaria

2010-01-01

Full Text Available Periodontitis is a relatively common disease. Various therapies have been recommended for its treatment which includes nonsurgical, antimicrobial, and surgical therapy. In recent years lasers have been used for all the three above-mentioned purposes. Lasers have been applied for hard and soft tissue debridement, contouring as well as the bacterial load reduction in the pocket. Here we present a case report of chronic periodontitis treated with the help of a new technique, laser-assisted modified Widman flap (LAMWF. The surgical procedure followed with a 980 nm diode laser has been described. The present case report resulted in significant pocket depth reduction, attachment gain, and radiographic evidence of bone fill. The laser-assisted modified Widman flap provided excellent results without complications and high patient as well as clinician satisfaction.

Hardfacing of aluminium alloys by means of metal matrix composites produced by laser surface alloying

CSIR Research Space (South Africa)

Pityana, SL

2009-06-01

Full Text Available . In these experiments the laser power was varied from 3 to 4.0 kW, the laser scan speed was varied from 0.8 to 2.0 m/min. The powder feed rate was varied from 2 to 5 g/min. The structural characterisation of the metal matrix composite included X-ray diffraction (XRD...

Mechanical Properties of TC4 Matrix Composites Prepared by Laser Cladding

Directory of Open Access Journals (Sweden)

WANG Lin

2017-06-01

Full Text Available In order to improve the penetration performance of TC4, the direct laser deposition technology was used to prepare TC4 composite material. TA15+30% TiC powder, TA15+20%Cr3C2 powder and TA15+15%B4C powder were used as deposited materials for TC4 matrix. The micromorphology, change of hardness of the deposited coating and mechanical properties of the three composites were studied. The experimental results demonstrate that the TC4 matrix with the three kinds of materials can form a complete metallurgical bonding, and the strength of TC4-(TA15+TiC, TC4-(TA15+Cr3C2 and TC4-(TA15+B4C are higher than that of TC4 matrix materials, while the plasticity is slightly worse.

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

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

International Nuclear Information System (INIS)

Zhang, Yaping; Wang, Yanmin; Guo, Shuai; Guo, Yumei; Liu, Hui; Li, Zhili

2013-01-01

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 17:0 ) versus their corresponding intensity ratios were constructed for C 14:0 , C 16:1 , C 16:0 , C 18:0 , C 18:1 , C 18:2 , C 18:3 , C 20:4 , and C 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 controls and patients without

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source.

Science.gov (United States)

Yang, Xixiang; Imasaka, Tomoko; Imasaka, Totaro

2018-04-03

A standard sample mixture containing 51 pesticides was separated by gas chromatography (GC), and the constituents were identified by mass spectrometry (MS) using femtosecond lasers emitting at 267, 400, and 800 nm as the ionization source. A two-dimensional display of the GC/MS was successfully used for the determination of these compounds. A molecular ion was observed for 38 of the compounds at 267 nm and for 30 of the compounds at 800 nm, in contrast to 27 among 50 compounds when electron ionization was used. These results suggest that the ultraviolet laser is superior to the near-infrared laser for molecular weight determinations and for a more reliable analysis of these compounds. In order to study the conditions for optimal ionization, the experimental data were examined using the spectral properties (i.e., the excitation and ionization energies and absorption spectra for the neutral and ionized species) obtained by quantum chemical calculations. A few molecules remained unexplained by the currently reported rules, requiring additional rules for developing a full understanding of the femtosecond ionization process. The pesticides in the homogenized matrix obtained from kabosu ( citrus sphaerocarpa) were measured using lasers emitting at 267 and 800 nm. The pesticides were clearly separated and measured on the two-dimensional display, especially for the data measured at 267 nm, suggesting that this technique would have potential for use in the practical trace analysis of the pesticides in the environment.

Identification of proteins in a human pleural exudate using two-dimensional preparative liquid-phase electrophoresis and matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Nilsson, C L; Puchades, M; Westman, A; Blennow, K; Davidsson, P

1999-01-01

Pleural effusion may occur in patients suffering from physical trauma or systemic disorders such as infection, inflammation, or cancer. In order to investigate proteins in a pleural exudate from a patient with severe pneumonia, we used a strategy that combined preparative two-dimensional liquid-phase electrophoresis (2-D LPE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and Western blotting. Preparative 2-D LPE is based on the same principles as analytical 2-D gel electrophoresis, except that the proteins remain in liquid phase during the entire procedure. In the first dimension, liquid-phase isoelectric focusing allows for the enrichment of proteins in liquid fractions. In the Rotofor cell, large volumes (up to 55 mL) and protein amounts (up to 1-2 g) can be loaded. Several low abundance proteins, cystatin C, haptoglobin, transthyretin, beta2-microglobulin, and transferrin, were detected after liquid-phase isoelectric focusing, through Western blotting analysis, in a pleural exudate (by definition, >25 g/L total protein). Direct MALDI-TOF-MS analysis of proteins in a Rotofor fraction is demonstrated as well. MALDI-TOF-MS analysis of a tryptic digest of a continuous elution sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) fraction confirmed the presence of cystatin C. By applying 2-D LPE, MALDI-TOF-MS, and Western blotting to the analysis of this pleural exudate, we were able to confirm the identity of proteins of potential diagnostic value. Our findings serve to illustrate the usefulness of this combination of methods in the analysis of pathological fluids.

Direct bacterial identification in positive blood cultures by use of two commercial matrix-assisted laser desorption ionization-time of flight mass spectrometry systems.

Science.gov (United States)

Chen, Jonathan H K; Ho, Pak-Leung; Kwan, Grace S W; She, Kevin K K; Siu, Gilman K H; Cheng, Vincent C C; Yuen, Kwok-Yung; Yam, Wing-Cheong

2013-06-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria and fungi was recently introduced in microbiology laboratories. This technology could greatly improve the clinical management of patients and guidance for chemotherapy. In this study, we used a commercial MALDI Sepsityper extraction method to evaluate the performance of two commercial MALDI-TOF MS systems, the Vitek MS IVD (bioMérieux) and the Microflex LT Biotyper (Bruker Daltonics) for direct bacterial identification in positive blood cultures. In 181 monomicrobial cultures, both systems generated genus to species level identifications for >90% of the specimens (Biotyper, 177/181 [97.8%]; Vitek MS IVD, 167/181 [92.3%]). Overall, the Biotyper system generated significantly more accurate identifications than the Vitek MS IVD system (P = 0.016; 177 versus 167 out of 181 specimens). The Biotyper system identified the minority species among polymicrobial blood cultures. We also compared the performance of an in-house extraction method with that of the Sepsityper on both MALDI-TOF MS systems. The in-house method generated more correct identifications at the genus level than the Sepsityper (96.7% versus 93.5%) on the Biotyper system, whereas the two methods exhibited the same performance level (88.0% versus 88.0%) on the Vitek MS IVD system. Our study confirmed the practical advantages of MALDI-TOF MS, and our in-house extraction method reduced the reagent cost to $1 per specimen, with a shorter turnaround time of 3 h, which is highly cost-effective for a diagnostic microbiology service.

Direct identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) from positive blood culture bottles: An opportunity to customize growth conditions for fastidious organisms causing bloodstream infections.

Science.gov (United States)

Sharma, Megha; Gautam, Vikas; Mahajan, Monika; Rana, Sudesh; Majumdar, Manasi; Ray, Pallab

2017-10-01

Culture-negative bacteraemia has been an enigmatic entity with respect to its aetiological agents. In an attempt to actively identify those positive blood cultures that escape isolation and detection on routine workflow, an additional step of MALDI-TOF MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) based detection was carried out directly from the flagged blood culture bottles. Blood samples from 200 blood culture bottles that beeped positive with automated (BACTEC) system and showed no growth of organism on routine culture media, were subjected to analysis by MALDI-TOF MS. Forty seven of the 200 (23.5%) bacterial aetiology could be established by bottle-based method. Based on these results, growth on culture medium could be achieved for the isolates by providing special growth conditions to the fastidious organisms. Direct identification by MALDI-TOF MS from BACTEC-positive bottles provided an opportunity to isolate those fastidious organisms that failed to grow on routine culture medium by providing them with necessary alterations in growth environment.

Chemically assisted laser ablation ICP mass spectrometry.

Science.gov (United States)

Hirata, Takafumi

2003-01-15

A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis.

Peeping into human renal calcium oxalate stone matrix: characterization of novel proteins involved in the intricate mechanism of urolithiasis.

Directory of Open Access Journals (Sweden)

Kanu Priya Aggarwal

Full Text Available BACKGROUND: The increasing number of patients suffering from urolithiasis represents one of the major challenges which nephrologists face worldwide today. For enhancing therapeutic outcomes of this disease, the pathogenic basis for the formation of renal stones is the need of hour. Proteins are found as major component in human renal stone matrix and are considered to have a potential role in crystal-membrane interaction, crystal growth and stone formation but their role in urolithiasis still remains obscure. METHODS: Proteins were isolated from the matrix of human CaOx containing kidney stones. Proteins having MW>3 kDa were subjected to anion exchange chromatography followed by molecular-sieve chromatography. The effect of these purified proteins was tested against CaOx nucleation and growth and on oxalate injured Madin-Darby Canine Kidney (MDCK renal epithelial cells for their activity. Proteins were identified by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF MS followed by database search with MASCOT server. In silico molecular interaction studies with CaOx crystals were also investigated. RESULTS: Five proteins were identified from the matrix of calcium oxalate kidney stones by MALDI-TOF MS followed by database search with MASCOT server with the competence to control the stone formation process. Out of which two proteins were promoters, two were inhibitors and one protein had a dual activity of both inhibition and promotion towards CaOx nucleation and growth. Further molecular modelling calculations revealed the mode of interaction of these proteins with CaOx at the molecular level. CONCLUSIONS: We identified and characterized Ethanolamine-phosphate cytidylyltransferase, Ras GTPase-activating-like protein, UDP-glucose:glycoprotein glucosyltransferase 2, RIMS-binding protein 3A, Macrophage-capping protein as novel proteins from the matrix of human calcium oxalate stone which play a critical role in kidney stone

RNase-assisted RNA chromatography

Science.gov (United States)

Michlewski, Gracjan; Cáceres, Javier F.

2010-01-01

RNA chromatography combined with mass spectrometry represents a widely used experimental approach to identify RNA-binding proteins that recognize specific RNA targets. An important drawback of most of these protocols is the high background due to direct or indirect nonspecific binding of cellular proteins to the beads. In many cases this can hamper the detection of individual proteins due to their low levels and/or comigration with contaminating proteins. Increasing the salt concentration during washing steps can reduce background, but at the cost of using less physiological salt concentrations and the likely loss of important RNA-binding proteins that are less stringently bound to a given RNA, as well as the disassembly of protein or ribonucleoprotein complexes. Here, we describe an improved RNA chromatography method that relies on the use of a cocktail of RNases in the elution step. This results in the release of proteins specifically associated with the RNA ligand and almost complete elimination of background noise, allowing a more sensitive and thorough detection of RNA-binding proteins recognizing a specific RNA transcript. PMID:20571124

Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

Science.gov (United States)

Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

2015-01-01

Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (pTooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method.

Science.gov (United States)

Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D

2016-09-19

Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface.

Thermally assisted nanosecond laser generation of ferric nanoparticles

Science.gov (United States)

Kurselis, K.; Kozheshkurt, V.; Kiyan, R.; Chichkov, B.; Sajti, L.

2018-03-01

A technique to increase nanosecond laser based production of ferric nanoparticles by elevating temperature of the iron target and controlling its surface exposure to oxygen is reported. High power near-infrared laser ablation of the iron target heated up to 600 °C enhances the particle generation efficiency by more than tenfold exceeding 6 μg/J. Temporal and thermal dependencies of the particle generation process indicate correlation of this enhancement with the oxidative processes that take place on the iron surface during the per spot interpulse delay. Nanoparticles, produced using the heat-assisted ablation technique, are examined using scanning electron and transmission electron microscopy confirming the presence of 1-100 nm nanoparticles with an exponential size distribution that contain multiple randomly oriented magnetite nanocrystallites. The described process enables the application of high power lasers and facilitates precise, uniform, and controllable direct deposition of ferric nanoparticle coatings at the industry-relevant rates.

Femtosecond laser-assisted compared with standard cataract surgery for removal of advanced cataracts.

Science.gov (United States)

Hatch, Kathryn M; Schultz, Tim; Talamo, Jonathan H; Dick, H Burkhard

2015-09-01

To compare effective phacoemulsification time (EPT) for the removal of brunescent cataracts treated with femtosecond laser-assisted cataract surgery with standard cataract phacoemulsification techniques. Ruhr University Eye Hospital, Bochum, Germany. Comparative prospective case study. The Lens Opacities Classification System III (LOCS III) grading system was used to measure eyes divided into 4 groups having cataract surgery. Groups 1 and 2 contained eyes with LOCS III grade nuclear opalescence (NO) 3 cataracts treated with standard cataract surgery and femtosecond laser-assisted cataract surgery, respectively. Groups 3 and 4 contained brunescent cataracts, LOCS III grades NO5, treated with standard cataract surgery and femtosecond laser-assisted cataract surgery, respectively. There were 240 eyes, with 60 eyes in each group. The EPT in Group 1 ranged from 0.46 to 3.10 (mean 1.38); the EPT in all eyes in Group 2 was 0 (P Talamo, and Dick are consultants to Abbott Medical Optics, Inc. Dr. Schultz has no financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Chromatography resin support

Science.gov (United States)

Dobos, James G.

2002-01-01

An apparatus and method of using an improved chromatography resin support is disclosed. The chromatography support platform is provided by a stainless steel hollow cylinder adapted for being inserted into a chromatography column. An exterior wall of the stainless steel cylinder defines a groove for carrying therein an "O"-ring. The upper surface of the stainless steel column is covered by a fine stainless steel mesh welded to the edges of the stainless steel cylinder. When placed upon a receiving ledge defined within a chromatography column, the "O"-ring provides a fluid tight seal with the inner edge wall of the chromatography cylinder. The stainless steel mesh supports the chromatography matrix and provides a back flushable support which is economical and simple to construct.

Laser deposition of sulfonated phthalocyanines for gas sensors

Czech Academy of Sciences Publication Activity Database

Fitl, Přemysl; Vrňata, M.; Kopecký, D.; Vlček, J.; Škodová, J.; Bulíř, Jiří; Novotný, Michal; Pokorný, Petr

2014-01-01

Roč. 302, MAY (2014), s. 37-41 ISSN 0169-4332. [European-Materials-Research-Society Symposium on Laser Material Interactions for Micro- and Nano- Applications /5./. Strasbourg, 27.05.2013-31.05.2013] R&D Projects: GA ČR(CZ) GAP108/11/1298 Institutional support: RVO:68378271 Keywords : Matrix Assisted Pulsed Laser Evaporation * substituted phthalocyanine s * gas sensors * impedance measurements Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.711, year: 2014

Aspects of matrix effects in applications of liquid chromatography-mass spectrometry to forensic and clinical toxicology--a review.

Science.gov (United States)

Peters, Frank T; Remane, Daniela

2012-06-01

In the last decade, liquid chromatography coupled to (tandem) mass spectrometry (LC-MS(-MS)) has become a versatile technique with many routine applications in clinical and forensic toxicology. However, it is well-known that ionization in LC-MS(-MS) is prone to so-called matrix effects, i.e., alteration in response due to the presence of co-eluting compounds that may increase (ion enhancement) or reduce (ion suppression) ionization of the analyte. Since the first reports on such matrix effects, numerous papers have been published on this matter and the subject has been reviewed several times. However, none of the existing reviews has specifically addressed aspects of matrix effects of particular interest and relevance to clinical and forensic toxicology, for example matrix effects in methods for multi-analyte or systematic toxicological analysis or matrix effects in (alternative) matrices almost exclusively analyzed in clinical and forensic toxicology, for example meconium, hair, oral fluid, or decomposed samples in postmortem toxicology. This review article will therefore focus on these issues, critically discussing experiments and results of matrix effects in LC-MS(-MS) applications in clinical and forensic toxicology. Moreover, it provides guidance on performance of studies on matrix effects in LC-MS(-MS) procedures in systematic toxicological analysis and postmortem toxicology.

Time-resolved study of absorbing film assisted laser induced forward transfer of Trichoderma longibrachiatum conidia

Energy Technology Data Exchange (ETDEWEB)

Hopp, B [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Smausz, T [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Barna, N [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Vass, Cs [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Antal, Zs [Hungarian Academy of Sciences and University of Szeged, Microbiological Research Group, PO Box 533, H-6701 Szeged (Hungary); Kredics, L [Hungarian Academy of Sciences and University of Szeged, Microbiological Research Group, PO Box 533, H-6701 Szeged (Hungary); Chrisey, D [Naval Research Laboratory, Washington, DC 20375 (United States)

2005-03-21

We have characterized the absorbing film assisted transfer of Trichoderma longibrachiatum conidia using a synchronized laser for illumination. The transfer laser used was a KrF excimer laser ({lambda} = 248 nm, FWHM = 30 ns) and the ejected material was illuminated parallel to the quartz plate by a nitrogen laser pumped Coumarine 153 dye laser beam ({lambda} = 453 nm, FWHM 1 ns) electronically delayed relative to the transfer UV pulse. Our time-resolved investigations determined that the ejection velocity front of the conidia plume from the donor surface during the transfer procedure was 1150 m s{sup -1} at 355 mJ cm{sup -2} applied laser fluence. On the basis of the measured data, the acceleration of the emitted conidia at the plume front was approximately 10{sup 9} x g. The conidia survived the absorbing film assisted forward transfer and associated mechanical shear without significant damages suggesting that the technique might be applicable to other more fragile types of biological objects and applications.

Time-resolved study of absorbing film assisted laser induced forward transfer of Trichoderma longibrachiatum conidia

International Nuclear Information System (INIS)

Hopp, B; Smausz, T; Barna, N; Vass, Cs; Antal, Zs; Kredics, L; Chrisey, D

2005-01-01

We have characterized the absorbing film assisted transfer of Trichoderma longibrachiatum conidia using a synchronized laser for illumination. The transfer laser used was a KrF excimer laser (λ = 248 nm, FWHM = 30 ns) and the ejected material was illuminated parallel to the quartz plate by a nitrogen laser pumped Coumarine 153 dye laser beam (λ = 453 nm, FWHM 1 ns) electronically delayed relative to the transfer UV pulse. Our time-resolved investigations determined that the ejection velocity front of the conidia plume from the donor surface during the transfer procedure was 1150 m s -1 at 355 mJ cm -2 applied laser fluence. On the basis of the measured data, the acceleration of the emitted conidia at the plume front was approximately 10 9 x g. The conidia survived the absorbing film assisted forward transfer and associated mechanical shear without significant damages suggesting that the technique might be applicable to other more fragile types of biological objects and applications

Endobronchial Forceps-Assisted and Excimer Laser-Assisted Inferior Vena Cava Filter Removal: The Data, Where We Are, and How It Is Done.

Science.gov (United States)

Chen, James X; Montgomery, Jennifer; McLennan, Gordon; Stavropoulos, S William

2018-06-01

The recognition of inferior vena cava filter related complications has motivated increased attentiveness in clinical follow-up of patients with inferior vena cava filters and has led to development of multiple approaches for retrieving filters that are challenging or impossible to remove using conventional techniques. Endobronchial forceps and excimer lasers are tools for designed to aid in complex inferior vena cava filter removals. This article discusses endobronchial forceps-assisted and excimer laser-assisted inferior vena cava filter retrievals. Copyright © 2018 Elsevier Inc. All rights reserved.

THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

Directory of Open Access Journals (Sweden)

Zita Iždinská

2010-09-01

Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

Raman microspectrometry of laser-reshaped rabbit auricular cartilage: preliminary study on laser-induced cartilage mineralization

Science.gov (United States)

Heger, Michal; Mordon, Serge R.; Leroy, Gérard; Fleurisse, Laurence; Creusy, Collette

2006-03-01

Laser-assisted cartilage reshaping (LACR) is a relatively novel technique designed to noninvasively and permanently restructure cartilaginous tissue. It is believed that heat-induced stress relaxation, in which a temperature-mediated disruption of H2O binding is associated with conformational alterations in the proteoglycan and collagen-rich matrix, constitutes the underlying mechanism of LACR. Several reports have suggested that laser-mediated cartilage mineralization may contribute to the permanent shape change of laser-reshaped cartilage. In an effort to validate these results in the context of Er:glass LACR, we performed a preliminary Raman microspectrometric study to characterize the crystal deposits in laser-irradiated chondrocytes and extracellular matrix. For the first time, we identified intracellular calcium sulfate deposits and extracellular calcium phosphate (apatite) crystals in laser-reshaped rabbit auricular cartilage. Calcium carbonate deposits are localized in both irradiated and nonirradiated samples, suggesting that this mineral plays no role in conformational retention. In our discussion, we elaborate on the possible molecular and cellular mechanisms responsible for intra- and extracellular crystallization, and propose a novel hypothesis on the formation of apatite, inasmuch as the biological function of this mineral (providing structure and rigidity in bones and dental enamel) may be extrapolated to the permanent shape change of laser-irradiated cartilage.

Laser assisted soldering: microdroplet accumulation with a microjet device.

Science.gov (United States)

Chan, E K; Lu, Q; Bell, B; Motamedi, M; Frederickson, C; Brown, D T; Kovach, I S; Welch, A J

1998-01-01

We investigated the feasibility of a microjet to dispense protein solder for laser assisted soldering. Successive micro solder droplets were deposited on rat dermis and bovine intima specimens. Fixed laser exposure was synchronized with the jetting of each droplet. After photocoagulation, each specimen was cut into two halves at the center of solder coagulum. One half was fixed immediately, while the other half was soaked in phosphate-buffered saline for a designated hydration period before fixation (1 hour, 1, 2, and 7 days). After each hydration period, all tissue specimens were prepared for scanning electron microscopy (SEM). Stable solder coagulum was created by successive photocoagulation of microdroplets even after the soldered tissue exposed to 1 week of hydration. This preliminary study suggested that tissue soldering with successive microdroplets is feasible even with fixed laser parameters without active feedback control.

Cell patterning by laser-assisted bioprinting.

Science.gov (United States)

Devillard, Raphaël; Pagès, Emeline; Correa, Manuela Medina; Kériquel, Virginie; Rémy, Murielle; Kalisky, Jérôme; Ali, Muhammad; Guillotin, Bertrand; Guillemot, Fabien

2014-01-01

The aim of tissue engineering is to produce functional three-dimensional (3D) tissue substitutes. Regarding native organ and tissue complexity, cell density and cell spatial 3D organization, which influence cell behavior and fate, are key parameters in tissue engineering. Laser-Assisted Bioprinting (LAB) allows one to print cells and liquid materials with a cell- or picoliter-level resolution. Thus, LAB seems to be an emerging and promising technology to fabricate tissue-like structures that have the physiological functionality of their native counterparts. This technology has additional advantages such as automation, reproducibility, and high throughput. It makes LAB compatible with the (industrial) fabrication of 3D constructs of physiologically relevant sizes. Here we present exhaustively the numerous steps that allow printing of viable cells with a well-preserved micrometer pattern. To facilitate the understanding of the whole cell patterning experiment using LAB, it is discussed in two parts: (1) preprocessing: laser set-up, bio-ink cartridge and bio-paper preparation, and pattern design; and (2) processing: bio-ink printing on the bio-paper. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of laser energy and wavelength on the analysis of LiFePO4 using laser assisted atom probe tomography

International Nuclear Information System (INIS)

Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Richard L.; Janssen, Yuri; Khalifah, Peter; Meng, Ying Shirley

2015-01-01

The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO 4 by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygen concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of 16 O 2 + ions. Green laser assisted field evaporation led to the selective loss of Li (∼33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO 4 . Plotting of multihit events on Saxey plots also revealed a strong neutral O 2 loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency. - Highlights: • Laser wavelength and pulse energy affect accuracy of APT analysis of LiFePO 4 . • Oxygen deficiency observed for UV laser; stronger at higher laser energies. • Selective loss of Li with green laser due to dc evaporation. • Saxey plots reveal prevalent formation of O 2 neutrals. • Quantification of molecular dissociations cannot account for O deficiency

Clinical assessment of diode laser-assisted endoscopic intrasphenoidal vidian neurectomy in the treatment of refractory rhinitis.

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Lai, Wen-Sen; Cheng, Sheng-Yao; Lin, Yuan-Yung; Yang, Pei-Lin; Lin, Hung-Che; Cheng, Li-Hsiang; Yang, Jinn-Moon; Lee, Jih-Chin

2017-12-01

For chronic rhinitis that is refractory to medical therapy, surgical intervention such as endoscopic vidian neurectomy (VN) can be used to control the intractable symptoms. Lasers can contribute to minimizing the invasiveness of ENT surgery. The aim of this retrospective study is to compare in patients who underwent diode laser-assisted versus traditional VN in terms of operative time, surgical field, quality of life, and postoperative complications. All patients had refractory rhinitis with a poor treatment response to a 6-month trial of corticosteroid nasal sprays and underwent endoscopic VN between November 2006 and September 2015. They were non-randomly allocated into either a cold instrument group or a diode laser-assisted group. Vidian nerve was excised with a 940-nm continuous wave diode laser through a 600-μm silica optical fiber, utilizing a contact mode with the power set at 5 W. A visual analog scale (VAS) was used to grade the severity of the rhinitis symptoms for quality of life assessment before the surgery and 6 months after. Of the 118 patients enrolled in the study, 75 patients underwent cold instrument VN and 43 patients underwent diode laser-assisted VN. Patients in the laser-assisted group had a significantly lower surgical field score and a lower postoperative bleeding rate than those in the cold instrument group. Changes in the VAS were significant in preoperative and postoperative nasal symptoms in each group. The application of diode lasers for vidian nerve transection showed a better surgical field and a lower incidence of postoperative hemorrhage. Recent advancements in laser application and endoscopic technique has made VN safer and more effective. We recommend this surgical approach as a reliable and effective treatment for patients with refractory rhinitis.

Laser assisted fabrication of random rough surfaces for optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Brissonneau, V., E-mail: vincent.brissonneau@im2np.fr [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Escoubas, L. [Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Flory, F. [Institut Materiaux Microelectronique Nanosciences de Provence, Ecole Centrale Marseille, Marseille (France); Berginc, G. [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Maire, G.; Giovannini, H. [Institut Fresnel, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Random rough surfaces are photofabricated using an argon ion laser. Black-Right-Pointing-Pointer Speckle and surface correlation function are linked. Black-Right-Pointing-Pointer Exposure beam is modified allowing tuning the correlation. Black-Right-Pointing-Pointer Theoretical examples are presented. Black-Right-Pointing-Pointer Experimental results are compared with theoretical expectation. - Abstract: Optical surface structuring shows great interest for antireflective or scattering properties. Generally, fabricated surface structures are periodical but random surfaces that offer new degrees of freedom and possibilities by the control of their statistical properties. We propose an experimental method to create random rough surfaces on silicon by laser processing followed by etching. A photoresist is spin coated onto a silicon substrate and then exposed to the scattering of a modified laser beam. The beam modification is performed by using a micromirror matrix allowing laser beam shaping. An example of tuning is presented. An image composed of two white circles with a black background is displayed and the theoretical shape of the correlation is calculated. Experimental surfaces are elaborated and the correlation function calculated from height mapping. We finally compared the experimental and theoretical correlation functions.

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.

Instant screening and verification of carbapenemase activity in Bacteroides fragilis in positive blood culture, using matrix-assisted laser desorption ionization--time of flight mass spectrometry.

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Johansson, Åsa; Nagy, Elisabeth; Sóki, József

2014-08-01

Rapid identification of isolates in positive blood cultures are of great importance to secure correct treatment of septicaemic patients. As antimicrobial resistance is increasing, rapid detection of resistance is crucial. Carbapenem resistance in Bacteroides fragilis associated with cfiA-encoded class B metallo-beta-lactamase is emerging. In our study we spiked blood culture bottles with 26 B. fragilis strains with various cfiA-status and ertapenem MICs. By using main spectra specific for cfiA-positive and cfiA-negative B. fragilis strains, isolates could be screened for resistance. To verify strains that were positive in the screening, a carbapenemase assay was performed where the specific peaks of intact and hydrolysed ertapenem were analysed with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). We show here that it is possible to correctly identify B. fragilis and to screen for enzymic carbapenem resistance directly from the pellet of positive blood cultures. The carbapenemase assay to verify the presence of the enzyme was successfully performed on the pellet from the direct identification despite the presence of blood components. The result of the procedure was achieved in 3 h. Also the Bruker mass spectrometric β-lactamase assay (MSBL assay) prototype software was proven not only to be based on an algorithm that correlated with the manual inspection of the spectra, but also to improve the interpretation by showing the variation in the dataset. © 2014 The Authors.

[Advantages and disadvantages of femtosecond laser assisted LASIK and SMILE].

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Zhang, F J; Sun, M S

2018-01-11

With the development of excimer laser and femtosecond laser equipment, application of diversified and customized surgical decision in modern corneal refractive surgery has been an inevitable trend. However, how to make a personalized decision with an accurate surgical design to achieve better visual quality becomes the main focus in clinical applications. Small-incision lenticule extraction (SMILE) and femtosecond assisted laser in situ keratomileusis (FS-LASIK) have been commonly acknowledged as the mainstream of corneal refractive surgery for ametropia correction nowadays. Both methods have been verified by clinical practice for many years. This article compares and elaborates the different characteristics with advantages and disadvantages of the two methods so as to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2018, 54: 7-10) .

Surface plasmon resonance assisted rapid laser joining of glass

Energy Technology Data Exchange (ETDEWEB)

Zolotovskaya, Svetlana A.; Tang, Guang; Abdolvand, Amin, E-mail: a.abdolvand@dundee.ac.uk [School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); Wang, Zengbo [School of Electronic Engineering, Bangor University, Bangor LL57 1UT (United Kingdom)

2014-08-25

Rapid and strong joining of clear glass to glass containing randomly distributed embedded spherical silver nanoparticles upon nanosecond pulsed laser irradiation (∼40 ns and repetition rate of 100 kHz) at 532 nm is demonstrated. The embedded silver nanoparticles were ∼30–40 nm in diameter, contained in a thin surface layer of ∼10 μm. A joint strength of 12.5 MPa was achieved for a laser fluence of only ∼0.13 J/cm{sup 2} and scanning speed of 10 mm/s. The bonding mechanism is discussed in terms of absorption of the laser energy by nanoparticles and the transfer of the accumulated localised heat to the surrounding glass leading to the local melting and formation of a strong bond. The presented technique is scalable and overcomes a number of serious challenges for a widespread adoption of laser-assisted rapid joining of glass substrates, enabling applications in the manufacture of microelectronic devices, sensors, micro-fluidic, and medical devices.

Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

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Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

2013-01-01

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

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Rychert, Jenna; Burnham, Carey-Ann D; Bythrow, Maureen; Garner, Omai B; Ginocchio, Christine C; Jennemann, Rebecca; Lewinski, Michael A; Manji, Ryhana; Mochon, A Brian; Procop, Gary W; Richter, Sandra S; Sercia, Linda; Westblade, Lars F; Ferraro, Mary Jane; Branda, John A

2013-07-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry identification of large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G.

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Jensen, Christian Salgård; Dam-Nielsen, Casper; Arpi, Magnus

2015-08-01

The aim of this study was to investigate whether large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G can be adequately identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF). Previous studies show varying results, with an identification rate from below 50% to 100%. Large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G isolated from blood cultures between January 1, 2007 and May 1, 2012 were included in the study. Isolates were identified to the species level using a combination of phenotypic characteristics and 16s rRNA sequencing. The isolates were subjected to MALDI-ToF analysis. We used a two-stage approach starting with the direct method. If no valid result was obtained we proceeded to an extraction protocol. Scores above 2 were considered valid identification at the species level. A total of 97 Streptococcus pyogenes, 133 Streptococcus dysgalactiae, and 2 Streptococcus canis isolates were tested; 94%, 66%, and 100% of S. pyogenes, S. dysgalactiae, and S. canis, respectively, were correctly identified by MALDI-ToF. In most instances when the isolates were not identified by MALDI-ToF this was because MALDI-ToF was unable to differentiate between S. pyogenes and S. dysgalactiae. By removing two S. pyogenes reference spectra from the MALDI-ToF database the proportion of correctly identified isolates increased to 96% overall. MALDI-ToF is a promising method for discriminating between S. dysgalactiae, S. canis, and S. equi, although more strains need to be tested to clarify this.

Direct identification of microorganisms from positive blood cultures using the lysis-filtration technique and matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS): a multicentre study.

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Farina, Claudio; Arena, Fabio; Casprini, Patrizia; Cichero, Paola; Clementi, Massimo; Cosentino, Marina; Degl'Innocenti, Roberto; Giani, Tommaso; Luzzaro, Francesco; Mattei, Romano; Mauri, Carola; Nardone, Maria; Rossolini, Gian Maria; Serna Ortega, Paula Andrea; Vailati, Francesca

2015-04-01

Microbial identification from blood cultures is essential to institute optimal antibiotic therapy and improve survival possibilities. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been successfully applied to identify bacteria and yeasts from positive blood cultures broths. The aim of this multicentre study was to evaluate the reliability of the lysis-filtration technique associated with MALDI-TOF MS to directly identify microorganisms from 765 positive blood cultures collected in six Italian hospitals. Overall, 675/765 (78.1%) blood isolates were correctly identified at the species level, with significant differences between Gram-negative and Gram-positive bacteria (92.6%, and 69.8%, respectively). Some difficulties arise in identifying Streptococcus pneumoniae, Staphylococcus aureus, yeasts and anaerobes. The lysis-filtration protocol is a suitable procedure in terms of performance in identifying microorganisms, but it is quite expensive and technically time-consuming since the time of filtration is not regular for all the samples. The application of the MALDI-TOF MS technique to the direct microbial identification from positive blood cultures is a very promising approach, even if more experience must be gained to minimize errors and costs.

Identification of rare pathogenic bacteria in a clinical microbiology laboratory: impact of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Science.gov (United States)

Seng, Piseth; Abat, Cedric; Rolain, Jean Marc; Colson, Philippe; Lagier, Jean-Christophe; Gouriet, Frédérique; Fournier, Pierre Edouard; Drancourt, Michel; La Scola, Bernard; Raoult, Didier

2013-07-01

During the past 5 years, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has become a powerful tool for routine identification in many clinical laboratories. We analyzed our 11-year experience in routine identification of clinical isolates (40 months using MALDI-TOF MS and 91 months using conventional phenotypic identification [CPI]). Among the 286,842 clonal isolates, 284,899 isolates of 459 species were identified. The remaining 1,951 isolates were misidentified and required confirmation using a second phenotypic identification for 670 isolates and using a molecular technique for 1,273 isolates of 339 species. MALDI-TOF MS annually identified 112 species, i.e., 36 species/10,000 isolates, compared to 44 species, i.e., 19 species/10,000 isolates, for CPI. Only 50 isolates required second phenotypic identifications during the MALDI-TOF MS period (i.e., 4.5 reidentifications/10,000 isolates) compared with 620 isolates during the CPI period (i.e., 35.2/10,000 isolates). We identified 128 bacterial species rarely reported as human pathogens, including 48 using phenotypic techniques (22 using CPI and 37 using MALDI-TOF MS). Another 75 rare species were identified using molecular methods. MALDI-TOF MS reduced the time required for identification by 55-fold and 169-fold and the cost by 5-fold and 96-fold compared with CPI and gene sequencing, respectively. MALDI-TOF MS was a powerful tool not only for routine bacterial identification but also for identification of rare bacterial species implicated in human infectious diseases. The ability to rapidly identify bacterial species rarely described as pathogens in specific clinical specimens will help us to study the clinical burden resulting from the emergence of these species as human pathogens, and MALDI-TOF MS may be considered an alternative to molecular methods in clinical laboratories.

Species identification of Aspergillus, Fusarium and Mucorales with direct surface analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

De Carolis, E; Posteraro, B; Lass-Flörl, C; Vella, A; Florio, A R; Torelli, R; Girmenia, C; Colozza, C; Tortorano, A M; Sanguinetti, M; Fadda, G

2012-05-01

Accurate species discrimination of filamentous fungi is essential, because some species have specific antifungal susceptibility patterns, and misidentification may result in inappropriate therapy. We evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification through direct surface analysis of the fungal culture. By use of culture collection strains representing 55 species of Aspergillus, Fusarium and Mucorales, a reference database was established for MALDI-TOF MS-based species identification according to the manufacturer's recommendations for microflex measurements and MALDI BioTyper 2.0 software. The profiles of young and mature colonies were analysed for each of the reference strains, and species-specific spectral fingerprints were obtained. To evaluate the database, 103 blind-coded fungal isolates collected in the routine clinical microbiology laboratory were tested. As a reference method for species designation, multilocus sequencing was used. Eighty-five isolates were unequivocally identified to the species level (≥99% sequence similarity); 18 isolates producing ambiguous results at this threshold were initially rated as identified to the genus level only. Further molecular analysis definitively assigned these isolates to the species Aspergillus oryzae (17 isolates) and Aspergillus flavus (one isolate), concordant with the MALDI-TOF MS results. Excluding nine isolates that belong to the fungal species not included in our reference database, 91 (96.8%) of 94 isolates were identified by MALDI-TOF MS to the species level, in agreement with the results of the reference method; three isolates were identified to the genus level. In conclusion, MALDI-TOF MS is suitable for the routine identification of filamentous fungi in a medical microbiology laboratory. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.

Matrix-assisted laser desorption ionization time of flight mass spectrometry and diagnostic testing for prosthetic joint infection in the clinical microbiology laboratory.

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Peel, Trisha N; Cole, Nicolynn C; Dylla, Brenda L; Patel, Robin

2015-03-01

Identification of pathogen(s) associated with prosthetic joint infection (PJI) is critical for patient management. Historically, many laboratories have not routinely identified organisms such as coagulase-negative staphylococci to the species level. The advent of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) has enhanced clinical laboratory capacity for accurate species-level identification. The aim of this study was to describe the species-level identification of microorganisms isolated from periprosthetic tissue and fluid specimens using MALDI-TOF MS alongside other rapid identification tests in a clinical microbiology laboratory. Results of rapid identification of bacteria isolated from periprosthetic joint fluid and/or tissue specimens were correlated with clinical findings at Mayo Clinic, Rochester, Minnesota, between May 2012 and May 2013. There were 178 PJI and 82 aseptic failure (AF) cases analyzed, yielding 770 organisms (median, 3/subject; range, 1-19/subject). MALDI-TOF MS was employed for the identification of 455 organisms (59%) in 197 subjects (123 PJIs and 74 AFs), with 89% identified to the species level using this technique. Gram-positive bacteria accounted for 68% and 93% of isolates in PJI and AF, respectively. However, the profile of species associated with infection compared to specimen contamination differed. Staphylococcus aureus and Staphylococcus caprae were always associated with infection, Staphylococcus epidermidis and Staphylococcus lugdunensis were equally likely to be a pathogen or a contaminant, whereas the other coagulase-negative staphylococci were more frequently contaminants. Most streptococcal and Corynebacterium isolates were pathogens. The likelihood that an organism was a pathogen or contaminant differed with the prosthetic joint location, particularly in the case of Propionibacterium acnes. MALDI-TOF MS is a valuable tool for the identification of bacteria isolated from patients

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.

Theory of the photoelectric effect assisted by an elliptically polarized laser field

International Nuclear Information System (INIS)

Li Shumin; Jentschura, Ulrich D

2009-01-01

The laser-assisted photoelectric effect in atomic hydrogen is investigated for linear, circular and general elliptic polarizations. The perturbative dressed state of the atom in an elliptically polarized nonresonant laser field is derived in the velocity gauge. The continuum state of the ejected electron is described by a Coulomb-Volkov wavefunction. Numerical results show that the ionization cross section by a vacuum ultraviolet photon is enhanced at high laser field intensities and low frequencies. At small and extremely large scattering angles (measured with respect to the wave vector of the incoming vacuum ultraviolet photon), the process for emitting a laser photon is predominant, while at medium angles, the result favours the process without a laser photon exchange. The dependence of the results on the laser polarization and on various geometries is studied, and an interesting pattern is found for the dependence on the frequency of the dressing laser; an intuitive explanation is offered.

Rapid and sensitive determination of phytosterols in functional foods and medicinal herbs by using UHPLC-MS/MS with microwave-assisted derivatization combined with dual ultrasound-assisted dispersive liquid-liquid microextraction.

Science.gov (United States)

Sun, Jing; Zhao, Xian-En; Dang, Jun; Sun, Xiaoyan; Zheng, Longfang; You, Jinmao; Wang, Xiao

2017-02-01

In this work, a hyphenated technique of dual ultrasound-assisted dispersive liquid-liquid microextraction combined with microwave-assisted derivatization followed by ultra high performance liquid chromatography tandem mass spectrometry has been developed for the determination of phytosterols in functional foods and medicinal herbs. Multiple reaction monitoring mode was used for the tandem mass spectrometry detection. A mass spectrometry sensitive reagent, 4'-carboxy-substituted rosamine, has been used as the derivatization reagent for five phytosterols, and internal standard diosgenin was used for the first time. Parameters for the dual microextraction, microwave-assisted derivatization, and ultra high performance liquid chromatography tandem mass spectrometry were all optimized in detail. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect, extremely low limits of detection (0.005-0.015 ng/mL) and limits of quantification (0.030-0.10 ng/mL) were achieved. The proposed method was compared with previously reported methods. It showed better sensitivity, selectivity, and accuracy. The matrix effect was also significantly reduced. The proposed method was successfully applied to the determination of five phytosterols in vegetable oil (sunflower oil, olive oil, corn oil, peanut oil), milk and orange juice (soymilk, peanut milk, orange juice), and medicinal herbs (Ginseng, Ganoderma lucidum, Cordyceps, Polygonum multiflorum) for the quality control of functional foods and medicinal herbs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid-phase dispersion with vortex-assisted dispersive liquid-liquid microextraction and HPLC with diode array detection.

Science.gov (United States)

Wang, Xiaozhong; Li, Xuwen; Li, Lanjie; Li, Min; Liu, Ying; Wu, Qian; Li, Peng; Jin, Yongri

2016-05-01

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid-phase dispersion combined with vortex-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid-phase dispersion and the eluate obtained was concentrated and further clarified by vortex-assisted dispersive liquid-liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6-2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laser-assisted electron scattering in strong-field ionization of dense water vapor by ultrashort laser pulses

International Nuclear Information System (INIS)

Wilke, M; Al-Obaidi, R; Moguilevski, A; Kothe, A; Engel, N; Metje, J; Kiyan, I Yu; Aziz, E F

2014-01-01

We report on strong-field ionization of dense water gas in a short infrared laser pulse. By employing a unique combination of photoelectron spectroscopy with a liquid micro-jet technique, we observe how the character of electron emission at high kinetic energies changes with the increase of the medium density. This change is associated with the process of laser-assisted electron scattering (LAES) on neighboring particles, which becomes a dominant mechanism of hot electron emission at higher medium densities. The manifestation of this mechanism is found to require densities that are orders of magnitude lower than those considered for heating the laser-generated plasmas via the LAES process. The experimental results are supported by simulations of the LAES yield with the use of the Kroll–Watson theory. (paper)

Preliminary observation of refractive cataract surgery assisted by femtosecond laser

Directory of Open Access Journals (Sweden)

Xiao-Li Wang

2015-12-01

Full Text Available AIM:To compare the differences of visual acuity and corneal astigmatism postoperatively between conventional refractive cataract surgery and that assisted by femtosecond laser.METHODS:Sixty patients(60 eyeswith age-related cataract and cornea astigmatism were divided into femtosecond group and conventional group randomly or voluntarily. The flat shaft, steep shaft and diopter of corneal astigmatism in patients in femtosecond group were inputted into the online vector calculators to get the location and width of the incision. Then femtosecond laser was used to make corneal releasing incision, the main and auxiliary incision. Phacoemulsification and aspheric multifocal intraocular lens implantation were undergone. Patients in conventional group received full-thickness relaxing incision by cornea paracentesis knife at the steepest meridian axis during phacoemulsification. Then aspheric multifocal intraocular lenses were implanted. Uncorrected distance visual acuity(UCDVA, uncorrected near visual acuity(UCNVAand cornea astigmatism were observed at 1d,1wk and 1mo postoperative. RESULTS:UCVA of patients in both groups was improved after the surgeries. UCDVA and UCNVA of femtosecond group were higher than those of conventional group, while the cornea astigmatism of femtosecond group was lower than that of conventional group.CONCLUSION:Refractile cataract surgery assisted by femtosecond laser canoffer better visual quality than conventional refractive cataract surgery because of lower cornea astigmatism and better visual acuity.