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Sample records for enhanced raman imaging

  1. Conjugated Polymer with Intrinsic Alkyne Units for Synergistically Enhanced Raman Imaging in Living Cells.

    Science.gov (United States)

    Li, Shengliang; Chen, Tao; Wang, Yunxia; Liu, Libing; Lv, Fengting; Li, Zhiliang; Huang, Yanyi; Schanze, Kirk S; Wang, Shu

    2017-10-16

    Development of Raman-active materials with enhanced and distinctive Raman vibrations in the Raman-silent region (1800-2800 cm -1 ) is highly required for specific molecular imaging of living cells with high spatial resolution. Herein, water-soluble cationic conjugated polymers (CCPs), poly(phenylene ethynylene) (PPE) derivatives, are explored for use as alkyne-state-dependent Raman probes for living cell imaging due to synergetic enhancement effect of alkyne vibrations in Raman-silent region compared to alkyne-containing small molecules. The enhanced alkyne signals result from the integration of alkyne groups into the rigid backbone and the delocalized π-conjugated structure. PPE-based conjugated polymer nanoparticles (CPNs) were also prepared as Raman-responsive nanomaterials for distinct imaging application. This work opens a new way into the development of conjugated polymer materials for enhanced Raman imaging. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Gap-enhanced Raman tags for high-contrast sentinel lymph node imaging.

    Science.gov (United States)

    Bao, Zhouzhou; Zhang, Yuqing; Tan, Ziyang; Yin, Xia; Di, Wen; Ye, Jian

    2018-05-01

    The sentinel lymph node (SLN) biopsy is gaining in popularity as a procedure to investigate the lymphatic metastasis of malignant tumors. The commonly used techniques to identify the SLNs in clinical practice are blue dyes-guided visualization, radioisotope-based detection and near-infrared fluorescence imaging. However, all these methods have not been found to perfectly fit the clinical criteria with issues such as short retention time in SLN, poor spatial resolution, autofluorescence, low photostability and high cost. In this study, we have reported a new type of nanoprobes, named, gap-enhanced Raman tags (GERTs) for the SLN Raman imaging. With the advantageous features including unique "fingerprint" Raman signal, strong Raman enhancement, high photostability, good biocompatibility and extra-long retention time, we have demonstrated that GERTs are greatly favorable for high-contrast and deep SLN Raman imaging, which meanwhile reveals the dynamic migration behavior of the probes entering the SLN. In addition, a quantitative volumetric Raman imaging (qVRI) data-processing method is employed to acquire a high-resolution 3-dimensional (3D) margin of SLN as well as the content variation of GERTs in the SLN. Moreover, SLN detection could be realized via a cost-effective commercial portable Raman scanner. Therefore, GERTs hold the great potential to be translated in clinical application for accurate and intraoperative location of the SLN. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Atomic force and shear force based tip-enhanced Raman spectroscopy and imaging

    NARCIS (Netherlands)

    Kharintsev, S.S.; Hoffmann, G.G.; Dorozhkin, P.S.; With, de G.; Loos, J.

    2007-01-01

    Underlying near-field optibal effects on the nanoscale have stimulated the development of apertureless vibrational spectroscopy and imaging with ultrahigh spatial resolution. We demonstrate tip-enhanced Raman spectra of single-walled carbon nanotubes (SWCNTs), recorded with a scanning near-field

  4. Graphene-enhanced Raman imaging of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Naumenko, Denys; Snitka, Valentinas; Snopok, Boris; Arpiainen, Sanna; Lipsanen, Harri

    2012-01-01

    The interaction of anatase titanium dioxide (TiO 2 ) nanoparticles with chemical vapour deposited graphene sheets transferred on glass substrates is investigated by using atomic force microscopy, Raman spectroscopy and imaging. Significant electronic interactions between the nanoparticles of TiO 2 and graphene were found. The changes in the graphene Raman peak positions and intensity ratios indicate that charge transfer between graphene and TiO 2 nanoparticles occurred, increasing the Raman signal of the TiO 2 nanoparticles up to five times. The normalized Raman intensity of TiO 2 nanoparticles per their volume increased with the disorder of the graphene structure. The complementary reason for the observed enhancement is that due to the higher density of states in the defect sites of graphene, a higher electron transfer occurs from the graphene to the anatase TiO 2 nanoparticles. (paper)

  5. Raman Imaging Techniques and Applications

    CERN Document Server

    2012-01-01

    Raman imaging has long been used to probe the chemical nature of a sample, providing information on molecular orientation, symmetry and structure with sub-micron spatial resolution. Recent technical developments have pushed the limits of micro-Raman microscopy, enabling the acquisition of Raman spectra with unprecedented speed, and opening a pathway to fast chemical imaging for many applications from material science and semiconductors to pharmaceutical drug development and cell biology, and even art and forensic science. The promise of tip-enhanced raman spectroscopy (TERS) and near-field techniques is pushing the envelope even further by breaking the limit of diffraction and enabling nano-Raman microscopy.

  6. Detection of latent prints by Raman imaging

    Science.gov (United States)

    Lewis, Linda Anne [Andersonville, TN; Connatser, Raynella Magdalene [Knoxville, TN; Lewis, Sr., Samuel Arthur

    2011-01-11

    The present invention relates to a method for detecting a print on a surface, the method comprising: (a) contacting the print with a Raman surface-enhancing agent to produce a Raman-enhanced print; and (b) detecting the Raman-enhanced print using a Raman spectroscopic method. The invention is particularly directed to the imaging of latent fingerprints.

  7. Cetuximab-conjugated nanodiamonds drug delivery system for enhanced targeting therapy and 3D Raman imaging.

    Science.gov (United States)

    Li, Dandan; Chen, Xin; Wang, Hong; Liu, Jie; Zheng, Meiling; Fu, Yang; Yu, Yuan; Zhi, Jinfang

    2017-12-01

    In this study, a multicomponent nanodiamonds (NDs)-based targeting drug delivery system, cetuximab-NDs-cisplatin bioconjugate, combining both specific targeting and enhanced therapeutic efficacy capabilities, is developed and characterized. The specific targeting ability of cetuximab-NDs-cisplatin system on human liver hepatocellular carcinoma (HepG2) cells is evaluated through epidermal growth factor receptor (EGFR) blocking experiments, since EGFR is over-expressed on HepG2 cell membrane. Besides, cytotoxic evaluation confirms that cetuximab-NDs-cisplatin system could significantly inhibit the growth of HepG2 cells, and the therapeutic activity of this system is proven to be better than that of both nonspecific NDs-cisplatin conjugate and specific EGF-NDs-cisplatin conjugate. Furthermore, a 3-dimensional (3D) Raman imaging technique is utilized to visualize the targeting efficacy and enhanced internalization of cetuximab-NDs-cisplatin system in HepG2 cells, using the NDs existing in the bioconjugate as Raman probes, based on the characteristic Raman signal of NDs at 1332 cm -1 . These advantageous properties of cetuximab-NDs-cisplatin system propose a prospective imaging and treatment tool for further diagnostic and therapeutic purposes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

    Science.gov (United States)

    MacLaughlin, Christina M.

    Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

  9. Surface-enhanced Raman imaging of cell membrane by a highly homogeneous and isotropic silver nanostructure

    Science.gov (United States)

    Zito, Gianluigi; Rusciano, Giulia; Pesce, Giuseppe; Dochshanov, Alden; Sasso, Antonio

    2015-04-01

    Label-free chemical imaging of live cell membranes can shed light on the molecular basis of cell membrane functionalities and their alterations under membrane-related diseases. In principle, this can be done by surface-enhanced Raman scattering (SERS) in confocal microscopy, but requires engineering plasmonic architectures with a spatially invariant SERS enhancement factor G(x, y) = G. To this end, we exploit a self-assembled isotropic nanostructure with characteristics of homogeneity typical of the so-called near-hyperuniform disorder. The resulting highly dense, homogeneous and isotropic random pattern consists of clusters of silver nanoparticles with limited size dispersion. This nanostructure brings together several advantages: very large hot spot density (~104 μm-2), superior spatial reproducibility (SD nanotoxicity issues. See DOI: 10.1039/c5nr01341k

  10. Glioblastoma cells labeled by robust Raman tags for enhancing imaging contrast.

    Science.gov (United States)

    Huang, Li-Ching; Chang, Yung-Ching; Wu, Yi-Syuan; Sun, Wei-Lun; Liu, Chan-Chuan; Sze, Chun-I; Chen, Shiuan-Yeh

    2018-05-01

    Complete removal of a glioblastoma multiforme (GBM), a highly malignant brain tumor, is challenging due to its infiltrative characteristics. Therefore, utilizing imaging agents such as fluorophores to increase the contrast between GBM and normal cells can help neurosurgeons to locate residual cancer cells during image guided surgery. In this work, Raman tag based labeling and imaging for GBM cells in vitro is described and evaluated. The cell membrane of a GBM adsorbs a substantial amount of functionalized Raman tags through overexpression of the epidermal growth factor receptor (EGFR) and "broadcasts" stronger pre-defined Raman signals than normal cells. The average ratio between Raman signals from a GBM cell and autofluorescence from a normal cell can be up to 15. In addition, the intensity of these images is stable under laser illuminations without suffering from the severe photo-bleaching that usually occurs in fluorescent imaging. Our results show that labeling and imaging GBM cells via robust Raman tags is a viable alternative method to distinguish them from normal cells. This Raman tag based method can be used solely or integrated into an existing fluorescence system to improve the identification of infiltrative glial tumor cells around the boundary, which will further reduce GBM recurrence. In addition, it can also be applied/extended to other types of cancer to improve the effectiveness of image guided surgery.

  11. Unveiling NIR Aza-Boron-Dipyrromethene (BODIPY) Dyes as Raman Probes: Surface-Enhanced Raman Scattering (SERS)-Guided Selective Detection and Imaging of Human Cancer Cells.

    Science.gov (United States)

    Adarsh, Nagappanpillai; Ramya, Adukkadan N; Maiti, Kaustabh Kumar; Ramaiah, Danaboyina

    2017-10-12

    The development of new Raman reporters has attracted immense attention in diagnostic research based on surface enhanced Raman scattering (SERS) techniques, which is a well established method for ultrasensitive detection through molecular fingerprinting and imaging. Herein, for the first time, we report the unique and efficient Raman active features of the selected aza-BODIPY dyes 1-6. These distinctive attributes could be extended at the molecular level to allow detection through SERS upon adsorption onto nano-roughened gold surface. Among the newly revealed Raman reporters, the amino substituted derivative 4 showed high signal intensity at very low concentrations (ca. 0.4 μm for 4-Au). Interestingly, an efficient nanoprobe has been constructed by using gold nanoparticles as SERS substrate, and 4 as the Raman reporter (4-Au@PEG), which unexpectedly showed efficient recognition of three human cancer cells (lung: A549, cervical: HeLa, Fibrosarcoma: HT-1080) without any specific surface marker. We observed well reflected and resolved Raman mapping and characteristic signature peaks whereas, such recognition was not observed in normal fibroblast (3T3L1) cells. To confirm these findings, a SERS nanoprobe was conjugated with a specific tumour targeting marker, EGFR (Epidermal Growth Factor Receptor), a well known targeted agent for Human Fibrosarcoma (HT1080). This nanoprobe efficiently targeted the surface marker of HT1080 cells, threreby demonstrating its use as an ultrasensitive Raman probe for detection and targeted imaging, leaving normal cells unaffected. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Real-time molecular imaging throughout the entire cell cycle by targeted plasmonic-enhanced Rayleigh/Raman spectroscopy.

    Science.gov (United States)

    Kang, Bin; Austin, Lauren A; El-Sayed, Mostafa A

    2012-10-10

    Due to their strong enhancement of scattered light, plasmonic nanoparticles have been utilized for various biological and medical applications. Here, we describe a new technique, Targeted Plasmonic-Enhanced Single-Cell Rayleigh/Raman Spectroscopy, to monitor the molecular changes of any cell-component, such as the nucleus, during the different phases of its full cell cycle by simultaneously recording its Rayleigh images and Raman vibration spectra in real-time. The analysis of the observed Raman DNA and protein peaks allowed the different phases of the cell cycle to be identified. This technique could be used for disease diagnostics and potentially improve our understanding of the molecular mechanisms of cellular functions such as division, death, signaling, and drug action.

  13. Micro-raman and tip-enhanced raman spectroscopy of carbon allotropes

    NARCIS (Netherlands)

    Hoffmann, G.G.; With, de G.; Loos, J.

    2008-01-01

    Raman spectroscopic data are obtained on various carbon allotropes like diamond, amorphous carbon, graphite, graphene and single wall carbon nanotubes by micro-Raman spectroscopy, tip-enhanced Raman spectroscopy and tip-enhanced Raman spectroscopy imaging, and the potentials of these techniques for

  14. Surface enhanced raman scattering on tardigrada - Towards monitoring and imaging molecular structures in live cryptobiotic organisms

    DEFF Research Database (Denmark)

    Kneipp, Harald; Møbjerg, Nadja; Jørgensen, Aslak

    2013-01-01

    Tardigrades are microscopic metazoans which are able to survive extreme physical and chemical conditions by entering a stress tolerant state called cryptobiosis. At present, the molecular mechanisms behind cryptobiosis are still poorly understood. We show that surface enhanced Raman scattering su...

  15. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    weak Raman signal, which facilitates identification in chemi- cal and biological systems. Recently, single-molecule Raman scattering has enhanced the detection sensitivity limit of ... was working on the molecular diffraction of light, which ulti-.

  16. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

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

  17. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

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

  18. Surface enhanced Raman scattering imaging of developed thin-layer chromatography plates.

    Science.gov (United States)

    Freye, Chris E; Crane, Nichole A; Kirchner, Teresa B; Sepaniak, Michael J

    2013-04-16

    A method for hyphenating surface enhanced Raman scattering (SERS) and thin-layer chromatography (TLC) is presented that employs silver-polymer nanocomposites as an interface. Through the process of conformal blotting, analytes are transferred from TLC plates to nanocomposite films before being imaged via SERS. A procedure leading to maximum blotting efficiency was established by investigating various parameters such as time, pressure, and type and amount of blotting solvent. Additionally, limits of detection were established for test analytes malachite green isothiocyanate, 4-aminothiophenol, and Rhodamine 6G (Rh6G) ranging from 10(-7) to 10(-6) M. Band broadening due to blotting was minimal (∼10%) as examined by comparing the spatial extent of TLC-spotted Rh6G via fluorescence and then the SERS-based spot size on the nanocomposite after the blotting process. Finally, a separation of the test analytes was carried out on a TLC plate followed by blotting and the acquisition of distance × wavenumber × intensity three-dimensional TLC-SERS plots.

  19. Evans blue dye-enhanced imaging of the brain microvessels using spectral focusing coherent anti-Stokes Raman scattering microscopy.

    Directory of Open Access Journals (Sweden)

    Bo-Ram Lee

    Full Text Available We performed dye-enhanced imaging of mouse brain microvessels using spectral focusing coherent anti-Stokes Raman scattering (SF-CARS microscopy. The resonant signals from C-H stretching in forward CARS usually show high background intensity in tissues, which makes CARS imaging of microvessels difficult. In this study, epi-detection of back-scattered SF-CARS signals showed a negligible background, but the overall intensity of resonant CARS signals was too low to observe the network of brain microvessels. Therefore, Evans blue (EB dye was used as contrasting agent to enhance the back-scattered SF-CARS signals. Breakdown of brain microvessels by inducing hemorrhage in a mouse was clearly visualized using backward SF-CARS signals, following intravenous injection of EB. The improved visualization of brain microvessels with EB enhanced the sensitivity of SF-CARS, detecting not only the blood vessels themselves but their integrity as well in the brain vasculature.

  20. Facile synthesis of terminal-alkyne bioorthogonal molecules for live -cell surface-enhanced Raman scattering imaging through Au-core and silver/dopamine-shell nanotags.

    Science.gov (United States)

    Chen, Meng; Zhang, Ling; Yang, Bo; Gao, Mingxia; Zhang, Xiangmin

    2018-03-01

    Alkyne is unique, specific and biocompatible in the Raman-silent region of the cell, but there still remains a challenge to achieve ultrasensitive detection in living systems due to its weak Raman scattering. Herein, a terminal alkyne ((E)-2-[4-(ethynylbenzylidene)amino]ethane-1-thiol (EBAE)) with surface-enhanced Raman scattering is synthesized. The EBAE molecule possesses S- and C-termini, which can be directly bonded to gold nanoparticles and dopamine/silver by forming the Au-S chemical bond and the carbon-metal bond, respectively. The distance between Raman reporter and AuNPs/AgNPs can be reduced, contributing to forming hot-spot-based SERS substrate. The alkyne functionalized nanoparticles are based on Au core and encapsulating polydopamine shell, defined as Au-core and dopamine/Ag-shell (ACDS). The bimetallic ACDS induce strong SERS signals for molecular imaging that arise from the strong electromagnetic field. Furthermore, the EBAE provides a distinct peak in the cellular Raman-silent region with nearly zero background interference. The EBAE Raman signals could be tremendously enhanced when the Raman reporter is located at the middle of the Au-core and dopamine/Ag-shell. Therefore, this work could have huge potential benefits for the highly sensitive detection of intercellular information delivery by connecting the recognition molecules in biomedical diagnostics. Graphical abstract Terminal-alkyne-functionalized Au-core and silver/dopamine-shell nanotags for live-cell surface-enhanced Raman scattering imaging.

  1. Rapid and sensitive phenotypic marker detection on breast cancer cells using surface-enhanced Raman scattering (SERS) imaging.

    Science.gov (United States)

    Lee, Sangyeop; Chon, Hyangah; Lee, Jiyoung; Ko, Juhui; Chung, Bong Hyun; Lim, Dong Woo; Choo, Jaebum

    2014-01-15

    We report a surface-enhanced Raman scattering (SERS)-based cellular imaging technique to detect and quantify breast cancer phenotypic markers expressed on cell surfaces. This technique involves the synthesis of SERS nano tags consisting of silica-encapsulated hollow gold nanospheres (SEHGNs) conjugated with specific antibodies. Hollow gold nanospheres (HGNs) enhance SERS signal intensity of individual particles by localizing surface electromagnetic fields through pinholes in the hollow particle structures. This capacity to enhance imaging at the level of single molecules permits the use of HGNs to detect specific biological markers expressed in living cancer cells. In addition, silica encapsulation greatly enhances the stability of nanoparticles. Here we applied a SERS-based imaging technique using SEHGNs in the multiplex imaging of three breast cancer cell phenotypes. Expression of epidermal growth factor (EGF), ErbB2, and insulin-like growth factor-1 (IGF-1) receptors were assessed in the MDA-MB-468, KPL4 and SK-BR-3 human breast cancer cell lines. SERS imaging technology described here can be used to test the phenotype of a cancer cell and quantify proteins expressed on the cell surface simultaneously. Based on results, this technique may enable an earlier diagnosis of breast cancer than is currently possible and offer guidance in treatment. © 2013 Elsevier B.V. All rights reserved.

  2. Penetration of silver nanoparticles into porcine skin ex vivo using fluorescence lifetime imaging microscopy, Raman microscopy, and surface-enhanced Raman scattering microscopy.

    Science.gov (United States)

    Zhu, Yongjian; Choe, Chun-Sik; Ahlberg, Sebastian; Meinke, Martina C; Alexiev, Ulrike; Lademann, Juergen; Darvin, Maxim E

    2015-05-01

    In order to investigate the penetration depth of silver nanoparticles (Ag NPs) inside the skin, porcine ears treated with Ag NPs are measured by two-photon tomography with a fluorescence lifetime imaging microscopy (TPT-FLIM) technique, confocal Raman microscopy (CRM), and surface-enhanced Raman scattering (SERS) microscopy. Ag NPs are coated with poly-N-vinylpyrrolidone and dispersed in pure water solutions. After the application of Ag NPs, porcine ears are stored in the incubator for 24 h at a temperature of 37°C. The TPT-FLIM measurement results show a dramatic decrease of the Ag NPs' signal intensity from the skin surface to a depth of 4 μm. Below 4 μm, the Ag NPs' signal continues to decline, having completely disappeared at 12 to 14 μm depth. CRM shows that the penetration depth of Ag NPs is 11.1 ± 2.1 μm. The penetration depth measured with a highly sensitive SERS microscopy reaches 15.6 ± 8.3 μm. Several results obtained with SERS show that the penetration depth of Ag NPs can exceed the stratum corneum (SC) thickness, which can be explained by both penetration of trace amounts of Ag NPs through the SC barrier and by the measurements inside the hair follicle, which cannot be excluded in the experiment.

  3. Through tissue imaging of a live breast cancer tumour model using handheld surface enhanced spatially offset resonance Raman spectroscopy (SESORRS).

    Science.gov (United States)

    Nicolson, Fay; Jamieson, Lauren E; Mabbott, Samuel; Plakas, Konstantinos; Shand, Neil C; Detty, Michael R; Graham, Duncan; Faulds, Karen

    2018-04-21

    In order to improve patient survival and reduce the amount of unnecessary and traumatic biopsies, non-invasive detection of cancerous tumours is of imperative and urgent need. Multicellular tumour spheroids (MTS) can be used as an ex vivo cancer tumour model, to model in vivo nanoparticle (NP) uptake by the enhanced permeability and retention (EPR) effect. Surface enhanced spatially offset Raman spectroscopy (SESORS) combines both surface enhanced Raman spectroscopy (SERS) and spatially offset Raman spectroscopy (SORS) to yield enhanced Raman signals at much greater sub-surface levels. By utilizing a reporter that has an electronic transition in resonance with the laser frequency, surface enhanced resonance Raman scattering (SERRS) yields even greater enhancement in Raman signal. Using a handheld SORS spectrometer with back scattering optics, we demonstrate the detection of live breast cancer 3D MTS containing SERRS active NPs through 15 mm of porcine tissue. False color 2D heat intensity maps were used to determine tumour model location. In addition, we demonstrate the tracking of SERRS-active NPs through porcine tissue to depths of up to 25 mm. This unprecedented performance is due to the use of red-shifted chalcogenpyrylium-based Raman reporters to demonstrate the novel technique of surface enhanced spatially offset resonance Raman spectroscopy (SESORRS) for the first time. Our results demonstrate a significant step forward in the ability to detect vibrational fingerprints from a tumour model at depth through tissue. Such an approach offers significant promise for the translation of NPs into clinical applications for non-invasive disease diagnostics based on this new chemical principle of measurement.

  4. Imaging with extrinsic Raman labels

    NARCIS (Netherlands)

    Sijtsema, N M; Duindam, J J; Puppels, G J; Otto, C; Greve, J

    1996-01-01

    In two separate examples we demonstrate the use of extrinsic Raman scattering probes for imaging of biological samples. First, the distribution of cholesterol in a rat eye Lens is determined with the use of the Raman scattered light from filipin, a molecule which binds specifically to cholesterol.

  5. Design of SERS nanoprobes for Raman imaging: materials, critical factors and architectures.

    Science.gov (United States)

    Li, Mingwang; Qiu, Yuanyuan; Fan, Chenchen; Cui, Kai; Zhang, Yongming; Xiao, Zeyu

    2018-05-01

    Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications of Raman imaging. By adsorbing Raman molecules onto specific nanostructures such as noble metals, Raman signals can be significantly enhanced, termed surface-enhanced Raman scattering (SERS). Recent years have witnessed great interest in the development of SERS nanoprobes for Raman imaging. Rationally designed SERS nanoprobes have greatly enhanced Raman signals by several orders of magnitude, thus showing great potential for biomedical applications. In this review we elaborate on recent progress in design strategies with emphasis on material properties, modifying factors, and structural parameters.

  6. Enhanced Raman scattering in porous silicon grating.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

    2018-03-19

    The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

  7. Coherent Raman scattering: Applications in imaging and sensing

    Science.gov (United States)

    Cui, Meng

    In this thesis, I discuss the theory, implementation and applications of coherent Raman scattering to imaging and sensing. A time domain interferometric method has been developed to collect high resolution shot-noise-limited Raman spectra over the Raman fingerprint regime and completely remove the electronic background signal in coherent Raman scattering. Compared with other existing coherent Raman microscopy methods, this time domain approach is proved to be simpler and more robust in rejecting background signal. We apply this method to image polymers and biological samples and demonstrate that the same setup can be used to collect two photon fluorescence and self phase modulation signals. A signal to noise ratio analysis is performed to show that this time domain method has a comparable signal to noise ratio to spectral domain methods, which we confirm experimentally. The coherent Raman method is also compared with spontaneous Raman scattering. The conditions under which coherent methods provide signal enhancement are discussed and experiments are performed to compare coherent Raman scattering with spontaneous Raman scattering under typical biological imaging conditions. A critical power, above which coherent Raman scattering is more sensitive than spontaneous Raman scattering, is experimentally determined to be ˜1mW in samples of high molecule concentration with a 75MHz laser system. This finding is contrary to claims that coherent methods provide many orders of magnitude enhancement under comparable conditions. In addition to the far field applications, I also discuss the combination of our time domain coherent Raman method with near field enhancement to explore the possibility of sensing and near field imaging. We report the first direct time-resolved coherent Raman measurement performed on a nanostructured substrate for molecule sensing. The preliminary results demonstrate that sub 20 fs pulses can be used to obtain coherent Raman spectra from a small number

  8. Raman chemical imaging technology for food and agricultural applications

    Science.gov (United States)

    This paper presents Raman chemical imaging technology for inspecting food and agricultural products. The paper puts emphasis on introducing and demonstrating Raman imaging techniques for practical uses in food analysis. The main topics include Raman scattering principles, Raman spectroscopy measurem...

  9. Optimizing laser crater enhanced Raman spectroscopy.

    Science.gov (United States)

    Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

    2018-03-20

    Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

  10. Surface enhanced raman spectroscopy on chip

    DEFF Research Database (Denmark)

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

    2007-01-01

    In this paper we report low resolution surface enhanced Raman spectra (SERS) conducted with a chip based spectrometer. The flat field spectrometer presented here is fabricated in SU-8 on silicon, showing a resolution of around 3 nm and a free spectral range of around 100 nm. The output facet...... is projected onto a CCD element and visualized by a computer. To enhance the otherwise rather weak Raman signal, a nanosurface is prepared and a sample solutions is impregnated on this surface. The surface enhanced Raman signal is picked up using a Raman probe and coupled into the spectrometer via an optical...... fiber. The obtained spectra show that chip based spectrometer together with the SERS active surface can be used as Raman sensor....

  11. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Matthew W. [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  12. Ultrafast surface-enhanced Raman spectroscopy.

    Science.gov (United States)

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

    2015-08-07

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

  13. High Fidelity Raman Chemical Imaging of Materials

    Science.gov (United States)

    Bobba, Venkata Nagamalli Koteswara Rao

    The development of high fidelity Raman imaging systems is important for a number of application areas including material science, bio-imaging, bioscience and healthcare, pharmaceutical analysis, and semiconductor characterization. The use of Raman imaging as a characterization tool for detecting the amorphous and crystalline regions in the biopolymer poly-L-lactic acid (PLLA) is the precis of my thesis. In the first chapter, a brief insight about the basics of Raman spectroscopy, Raman chemical imaging, Raman mapping, and Raman imaging techniques has been provided. The second chapter contains details about the successful development of tailored sample of PLLA. Biodegradable polymers are used in areas of tissue engineering, agriculture, packaging, and in medical field for drug delivery, implant devices, and surgical sutures. Detailed information about the sample preparation and characterization of these cold-drawn PLLA polymer substrates has been provided. Wide-field Raman hyperspectral imaging using an acousto-optic tunable filter (AOTF) was demonstrated in the early 1990s. The AOTF contributed challenges such as image walk, distortion, and image blur. A wide-field AOTF Raman imaging system has been developed as part of my research and methods to overcome some of the challenges in performing AOTF wide-field Raman imaging are discussed in the third chapter. This imaging system has been used for studying the crystalline and amorphous regions on the cold-drawn sample of PLLA. Of all the different modalities that are available for performing Raman imaging, Raman point-mapping is the most extensively used method. The ease of obtaining the Raman hyperspectral cube dataset with a high spectral and spatial resolution is the main motive of performing this technique. As a part of my research, I have constructed a Raman point-mapping system and used it for obtaining Raman hyperspectral image data of various minerals, pharmaceuticals, and polymers. Chapter four offers

  14. Nanophotonics with Surface Enhanced Coherent Raman Microscopy

    Science.gov (United States)

    Fast, Alexander

    Nonlinear nanophotonics is a rapidly developing field of research that aims at detecting and disentangling weak congested optical signatures on the nanoscale. Sub-wavelength field confinement of the local electromagnetic fields and the resulting field enhancement is achieved by utilizing plasmonic near-field antennas. This allows for probing nanoscopic volumes, a property unattainable by conventional far-field microscopy techniques. Combination of plasmonics and nonlinear optical microscopy provides a path to visualizing a small chemical and spatial subset of target molecules within an ensemble. This is achieved while maintaining rapid signal acquisition, which is necessary for capturing biological processes in living systems. Herein, a novel technique, wide-field surface enhanced coherent anti-Stokes Raman scattering (wfSE-CARS) is presented. This technique allows for isolating weak vibrational signals in nanoscopic proximity to the surface by using chemical sensitivity of coherent Raman microspectroscopy (CRM) and field confinement from surface plasmons supported on a thin gold film. Uniform field enhancement over a large field of view, achieved with surface plasmon polaritons (SPP) in wfSE-CARSS, allows for biomolecular imaging demonstrated on extended structures like phospholipid droplets and live cells. Surface selectivity and chemical contrast are achieved at 70 fJ/mum2 incident energy densities, which is over five orders of magnitude lower than used in conventional point scanning CRM. Next, a novel surface sensing imaging technique, local field induced metal emission (LFIME), is introduced. Presence of a sample material at the surface influences the local fields of a thin flat gold film, such that nonlinear fluorescence signal of the metal can be detected in the far-field. Nanoscale nonmetallic, nonfluorescent objects can be imaged with high signal-to-background ratio and diffraction limited lateral resolution using LFIME. Additionally, structure of the

  15. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, Søren; Xiao, Sanshui

    2012-01-01

    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...

  16. Utilizing Raman Spectroscopy and Surface-Enhanced Raman Spectroscopy to investigate healthy and cancerous colon samples

    International Nuclear Information System (INIS)

    Barzegar, A.; Rezaei, H.; Malekfar, R.

    2012-01-01

    In this study, spontaneous Raman scattering and surface-enhanced Raman scattering, Surface-Enhanced Raman Spectroscopy spectra have been investigated. The samples which were kept in the formalin solution selected from the human's healthy and cancerous colon tissues. The Surface-Enhanced Raman Spectroscopy spectra were collected by adding colloidal solution contained silver nanoparticles to the top of the samples. The recorded spectra were compared for the spontaneous Raman spectra of healthy and cancerous colon samples. The spontaneous and surface enhanced Raman scattering data were also collected and compared for both healthy and damaged samples.

  17. Dynamic Raman imaging system with high spatial and temporal resolution

    Science.gov (United States)

    Wang, Lei; Dai, Yinzhen; He, Hao; Lv, Ruiqi; Zong, Cheng; Ren, Bin

    2017-09-01

    There is an increasing need to study dynamic changing systems with significantly high spatial and temporal resolutions. In this work, we integrated point-scanning, line-scanning, and wide-field Raman imaging techniques into a single system. By using an Electron Multiplying CCD (EMCCD) with a high gain and high frame rate, we significantly reduced the time required for wide-field imaging, making it possible to monitor the electrochemical reactions in situ. The highest frame rate of EMCDD was ˜50 fps, and the Raman images for a specific Raman peak can be obtained by passing the signal from the sample through the Liquid Crystal Tunable Filter. The spatial resolutions of scanning imaging and wide-field imaging with a 100× objective (NA = 0.9) are 0.5 × 0.5 μm2 and 0.36 × 0.36 μm2, respectively. The system was used to study the surface plasmon resonance of Au nanorods, the surface-enhanced Raman scattering signal distribution for Au Nanoparticle aggregates, and dynamic Raman imaging of an electrochemical reacting system.

  18. Optimizing laser crater enhanced Raman scattering spectroscopy

    Science.gov (United States)

    Lednev, V. N.; Sdvizhenskii, P. A.; Grishin, M. Ya.; Fedorov, A. N.; Khokhlova, O. V.; Oshurko, V. B.; Pershin, S. M.

    2018-05-01

    The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for L-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

  19. Tip-enhanced Raman mapping with top-illumination AFM.

    Science.gov (United States)

    Chan, K L Andrew; Kazarian, Sergei G

    2011-04-29

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of ∼ 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  20. Tip-enhanced Raman mapping with top-illumination AFM

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K L Andrew; Kazarian, Sergei G, E-mail: s.kazarian@imperial.ac.uk [Department of Chemical Engineering, Imperial College London, SW7 2AZ (United Kingdom)

    2011-04-29

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of {approx} 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  1. Tip-enhanced Raman mapping with top-illumination AFM

    International Nuclear Information System (INIS)

    Chan, K L Andrew; Kazarian, Sergei G

    2011-01-01

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of ∼ 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  2. Enhanced Raman scattering on functionalized graphene substrates

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Kovaříček, Petr; Fridrichová, Michaela; Ji, X.; Ling, X.; Kong, J.; Dresselhaus, M. S.; Kalbáč, Martin

    2017-01-01

    Roč. 4, č. 2 (2017), č. článku 025087. ISSN 2053-1583 R&D Projects: GA ČR(CZ) GA15-01953S Grant - others:AVČR PPPLZ(CZ) L200401551 Institutional support: RVO:61388955 Keywords : spectroscopy * molecules * graphene * graphene enhanced Raman scattering * functionalized graphene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 6.937, year: 2016

  3. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja

    2010-01-01

    Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives...

  4. Ultraviolet Resonant Raman Enhancements in the Detection of Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Short Jr., Billy Joe [Naval Postgraduate School, Monterey, CA (United States)

    2009-06-01

    Raman-based spectroscopy is potentially militarily useful for standoff detection of high explosives. Normal (non-resonance) and resonance Raman spectroscopies are both light scattering techniques that use a laser to measure the vibrational spectrum of a sample. In resonance Raman, the laser is tuned to match the wavelength of a strong electronic absorbance in the molecule of interest, whereas, in normal Raman the laser is not tuned to any strong electronic absorbance bands. The selection of appropriate excitation wavelengths in resonance Raman can result in a dramatic increase in the Raman scattering efficiency of select band(s) associated with the electronic transition. Other than the excitation wavelength, however, resonance Raman is performed experimentally the same as normal Raman. In these studies, normal and resonance Raman spectral signatures of select solid high explosive (HE) samples and explosive precursors were collected at 785 nm, 244 nm and 229 nm. Solutions of PETN, TNT, and explosive precursors (DNT & PNT) in acetonitrile solvent as an internal Raman standard were quantitatively evaluated using ultraviolet resonance Raman (UVRR) microscopy and normal Raman spectroscopy as a function of power and select excitation wavelengths. Use of an internal standard allowed resonance enhancements to be estimated at 229 nm and 244 nm. Investigations demonstrated that UVRR provided ~2000-fold enhancement at 244 nm and ~800-fold improvement at 229 nm while PETN showed a maximum of ~25-fold at 244 nm and ~190-fold enhancement at 229 nm solely from resonance effects when compared to normal Raman measurements. In addition to the observed resonance enhancements, additional Raman signal enhancements are obtained with ultraviolet excitation (i.e., Raman scattering scales as !4 for measurements based on scattered photons). A model, based partly on the resonance Raman enhancement results for HE solutions, is presented for estimating Raman enhancements for solid HE samples.

  5. SERS imaging of cell-surface biomolecules metabolically labeled with bioorthogonal Raman reporters.

    Science.gov (United States)

    Xiao, Ming; Lin, Liang; Li, Zefan; Liu, Jie; Hong, Senlian; Li, Yaya; Zheng, Meiling; Duan, Xuanming; Chen, Xing

    2014-08-01

    Live imaging of biomolecules with high specificity and sensitivity as well as minimal perturbation is essential for studying cellular processes. Here, we report the development of a bioorthogonal surface-enhanced Raman scattering (SERS) imaging approach that exploits small Raman reporters for visualizing cell-surface biomolecules. The cells were cultured and imaged by SERS microscopy on arrays of Raman-enhancing nanoparticles coated on silicon wafers or glass slides. The Raman reporters including azides, alkynes, and carbondeuterium bonds are small in size and spectroscopically bioorthogonal (background-free). We demonstrated that various cell-surface biomolecules including proteins, glycans, and lipids were metabolically incorporated with the corresponding precursors bearing a Raman reporter and visualized by SERS microscopy. The coupling of SERS microscopy with bioorthogonal Raman reporters expands the capabilities of live-cell microscopy beyond the modalities of fluorescence and label-free imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Raman imaging using fixed bandpass filter

    Science.gov (United States)

    Landström, L.; Kullander, F.; Lundén, H.; Wästerby, P.

    2017-05-01

    By using fixed narrow band pass optical filtering and scanning the laser excitation wavelength, hyperspectral Raman imaging could be achieved. Experimental, proof-of-principle results from the Chemical Warfare Agent (CWA) tabun (GA) as well as the common CWA simulant tributyl phosphate (TBP) on different surfaces/substrates are presented and discussed.

  7. Raman beam combining for laser brightness enhancement

    Science.gov (United States)

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  8. Spectroscopy and Raman imaging of inhomogeneous materials

    International Nuclear Information System (INIS)

    Maslova, Olga

    2014-01-01

    This thesis is aimed at developing methodologies in Raman spectroscopy and imaging. After reviewing the statistical instruments which allow treating giant amount of data (multivariate analysis and classification), the study is applied to two families of well-known materials which are used as models for testing the limits of the implemented developments. The first family is a series of carbon materials pyrolyzed at various temperatures and exhibiting inhomogeneities at a nm scale which is suitable for Raman-X-ray diffraction combination. Another results concern the polishing effect on carbon structure. Since it is found to induce Raman artifacts leading to the overestimation of the local structural disorder, a method based on the use of the G band width is therefore proposed in order to evaluate the crystallite size in both unpolished and polished nano-graphites. The second class of materials presents inhomogeneities at higher (micrometric) scales by the example of uranium dioxide ceramics. Being well adapted in terms of spatial scale, Raman imaging is thus used for probing their surfaces. Data processing is implemented via an approach combining the multivariate (principal component) analysis and the classical fitting procedure with Lorentzian profiles. The interpretation of results is supported via electron backscattering diffraction (EBSD) analysis which enables us to distinguish the orientation effects of ceramic grains from other underlying contributions. The last ones are mainly localized at the grain boundaries, that is testified by the appearance of a specific Raman mode. Their origin seems to be caused by stoichiometric oxygen variations or impurities, as well as strain inhomogeneities. The perspectives of this work include both the implementation of other mathematical methods and in-depth analysis of UO 2 structure damaged by irradiation (anisotropic effects, role of grain boundaries). (author) [fr

  9. Development of a Raman spectrometer to study surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Biswas, Nandita; Chadha, Ridhima; Kapoor, Sudhir; Sarkar, Sisir K.; Mukherjee, Tulsi

    2011-02-01

    Raman spectroscopy is an important tool, which provides enormous information on the vibrational and structural details of materials. This understanding is not only interesting due to its fundamental importance, but also of considerable importance in optoelectronics and device applications of these materials in nanotechnology. In this report, we begin with a brief introduction on the Raman effect and various Raman scattering techniques, followed by a detailed discussion on the development of an instrument with home-built collection optics attachment. This Raman system consists of a pulsed laser excitation source, a sample compartment, collection optics to collect the scattered light, a notch filter to reject the intense laser light, a monochromator to disperse the scattered light and a detector to detect the Raman signal. After calibrating the Raman spectrometer with standard solvents, we present our results on Surface-Enhanced Raman Scattering (SERS) investigations on three different kinds of chemical systems. (author)

  10. High Density Periodic Metal Nanopyramids for Surface Enhanced Raman Spectroscopy

    NARCIS (Netherlands)

    Jin, Mingliang

    2012-01-01

    The work presented in this thesis is focused on two areas. First, a new type of nanotextured noble-metal surface has been developed. The new nanotextured surface is demonstrated to enhance inelastic (Raman) scattering, called surface enhanced Raman scattering (SERS), from molecules adsorbed on the

  11. Surface enhanced Raman scattering spectroscopic waveguide

    Science.gov (United States)

    Lascola, Robert J; McWhorter, Christopher S; Murph, Simona H

    2015-04-14

    A waveguide for use with surface-enhanced Raman spectroscopy is provided that includes a base structure with an inner surface that defines a cavity and that has an axis. Multiple molecules of an analyte are capable of being located within the cavity at the same time. A base layer is located on the inner surface of the base structure. The base layer extends in an axial direction along an axial length of an excitation section. Nanoparticles are carried by the base layer and may be uniformly distributed along the entire axial length of the excitation section. A flow cell for introducing analyte and excitation light into the waveguide and a method of applying nanoparticles may also be provided.

  12. Laser ablation surface-enhanced Raman microspectroscopy.

    Science.gov (United States)

    Londero, Pablo S; Lombardi, John R; Leona, Marco

    2013-06-04

    Improved identification of trace organic compounds in complex matrixes is critical for a variety of fields such as material science, heritage science, and forensics. Surface-enhanced Raman scattering (SERS) is a vibrational spectroscopy technique that can attain single-molecule sensitivity and has been shown to complement mass spectrometry, but lacks widespread application without a robust method that utilizes the effect. We demonstrate a new, highly sensitive, and widely applicable approach to SERS analysis based on laser ablation in the presence of a tailored plasmonic substrate. We analyze several challenging compounds, including non-water-soluble pigments and dyed leather from an ancient Egyptian chariot, achieving sensitivity as high as 120 amol for a 1:1 signal-to-noise ratio and 5 μm spatial resolution. This represents orders of magnitude improvement in spatial resolution and sensitivity compared to those of other SERS approaches intended for widespread application, greatly increasing the applicability of SERS.

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

    Science.gov (United States)

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

    2015-02-01

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

  14. Raman microspectroscopy, surface-enhanced Raman scattering microspectroscopy, and stable-isotope Raman microspectroscopy for biofilm characterization.

    Science.gov (United States)

    Ivleva, Natalia P; Kubryk, Patrick; Niessner, Reinhard

    2017-07-01

    Biofilms represent the predominant form of microbial life on our planet. These aggregates of microorganisms, which are embedded in a matrix formed by extracellular polymeric substances, may colonize nearly all interfaces. Detailed knowledge of microorganisms enclosed in biofilms as well as of the chemical composition, structure, and functions of the complex biofilm matrix and their changes at different stages of the biofilm formation and under various physical and chemical conditions is relevant in different fields. Important research topics include the development and improvement of antibiotics and medical devices and the optimization of biocides, antifouling strategies, and biological wastewater treatment. Raman microspectroscopy is a capable and nondestructive tool that can provide detailed two-dimensional and three-dimensional chemical information about biofilm constituents with the spatial resolution of an optical microscope and without interference from water. However, the sensitivity of Raman microspectroscopy is rather limited, which hampers the applicability of Raman microspectroscopy especially at low biomass concentrations. Fortunately, the resonance Raman effect as well as surface-enhanced Raman scattering can help to overcome this drawback. Furthermore, the combination of Raman microspectroscopy with other microscopic techniques, mass spectrometry techniques, or particularly with stable-isotope techniques can provide comprehensive information on monospecies and multispecies biofilms. Here, an overview of different Raman microspectroscopic techniques, including resonance Raman microspectroscopy and surface-enhanced Raman scattering microspectroscopy, for in situ detection, visualization, identification, and chemical characterization of biofilms is given, and the main feasibilities and limitations of these techniques in biofilm research are presented. Future possibilities of and challenges for Raman microspectroscopy alone and in combination with other

  15. Electron enhanced Raman scattering and its applications in solution chemistry

    International Nuclear Information System (INIS)

    Yui, Hiroharu

    2007-01-01

    The present review describes a new enhancement technique for Raman scattering in aqueous solutions. Raman scattering spectroscopy has an inherent ability to distinguish between molecules with great similarity and provides useful information on local physical and chemical environments at their functional groups' level. Since the Raman scattering signals from water molecules are quite weak, Raman spectroscopy has great advantage for detection or discrimination of a trace amount of analytes in aqueous environments. However, Raman scattering cross-sections are inherently small and it generally requires high power excitation and long acquisition times to obtain high-quality Raman spectra. These conditions create disadvantages for the analyses for living cells and real-time monitoring for environmental analyses. Here, I describe a new Raman enhancement technique, namely electron enhanced Raman scattering (EERS)', where artificially generated electrons additionally affect the polarizability of target molecular systems and enhance their inherent Raman cross-section. Principles of the EERS and its applications to aqueous solution are presented. (author)

  16. Enhancing Raman signals with an interferometrically controlled AFM tip

    International Nuclear Information System (INIS)

    Oron-Carl, Matti; Krupke, Ralph

    2013-01-01

    We demonstrate the upgrade of a commercial confocal Raman microscope into a tip-enhanced Raman microscope/spectroscopy system (TERS) by integrating an interferometrically controlled atomic force microscope into the base of an existing upright microscope to provide near-field detection and thus signal enhancement. The feasibility of the system is demonstrated by measuring the Raman near-field enhancement on thin PEDOT:PSS films and on carbon nanotubes within a device geometry. An enhancement factor of 2–3 and of 5–6 is observed, respectively. Moreover, on a nanotube device we show local conductivity measurement and its correlation to Raman and topography recordings. Upgrading an existing upright confocal Raman microscope in the demonstrated way is significantly cheaper than purchasing a complete commercial TERS system. (paper)

  17. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  18. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    McAnally, Gerard David

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm -1 ) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are presented. A new band in the spectrum (1131 cm -1 ) is assigned to a complex vibration using a density functional calculation. Depth profiling through a polymer film on to the silver layer showed the SERS signals arise from the silver surface only. The profiles show the effects of refraction on the beam, and the adverse affect on the depth resolution. Silver films were used to obtain SERS spectra from a 40 nm thin-film coating on PET, without interference from the PET layer. The use of an azo dye probe as a marker to detect the coating is described. Finally, a novel method for the synthesis of a SERS-active vinyl-benzotriazole monomer is reported. The monomer was incorporated into a thin-film coating and the SERS spectrum obtained from the polymer. (author)

  19. NIR–FT Raman, FT–IR and surface-enhanced Raman scattering ...

    Indian Academy of Sciences (India)

    Administrator

    Single crystals of (S)-phenylsuccinic acid (SPSA) were grown by the slow evaporation tech- nique and vibrational ... the shift of Raman frequencies, enhancing or weak- ening of .... Harmonic vibrational wave numbers were cal- culated using ...

  20. Molecular selectivity of graphene-enhanced Raman scattering.

    Science.gov (United States)

    Huang, Shengxi; Ling, Xi; Liang, Liangbo; Song, Yi; Fang, Wenjing; Zhang, Jin; Kong, Jing; Meunier, Vincent; Dresselhaus, Mildred S

    2015-05-13

    Graphene-enhanced Raman scattering (GERS) is a recently discovered Raman enhancement phenomenon that uses graphene as the substrate for Raman enhancement and can produce clean and reproducible Raman signals of molecules with increased signal intensity. Compared to conventional Raman enhancement techniques, such as surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS), in which the Raman enhancement is essentially due to the electromagnetic mechanism, GERS mainly relies on a chemical mechanism and therefore shows unique molecular selectivity. In this paper, we report graphene-enhanced Raman scattering of a variety of different molecules with different molecular properties. We report a strong molecular selectivity for the GERS effect with enhancement factors varying by as much as 2 orders of magnitude for different molecules. Selection rules are discussed with reference to two main features of the molecule, namely its molecular energy levels and molecular structures. In particular, the enhancement factor involving molecular energy levels requires the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies to be within a suitable range with respect to graphene's Fermi level, and this enhancement effect can be explained by the time-dependent perturbation theory of Raman scattering. The enhancement factor involving the choice of molecular structures indicates that molecular symmetry and substituents similar to that of the graphene structure are found to be favorable for GERS enhancement. The effectiveness of these factors can be explained by group theory and the charge-transfer interaction between molecules and graphene. Both factors, involving the molecular energy levels and structural symmetry of the molecules, suggest that a remarkable GERS enhancement requires strong molecule-graphene coupling and thus effective charge transfer between the molecules and graphene. These conclusions are further

  1. Surface-Enhanced Raman Scattering Physics and Applications

    CERN Document Server

    Kneipp, Katrin; Kneipp, Harald

    2006-01-01

    Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. Yet, explaining the enhancement of a spectroscopic signal by fouteen orders of magnitude continues to attract the attention of physicists and chemists alike. And, at the same time and rapidly growing, SERS is becoming a very useful spectroscopic tool with exciting applications in many fields. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This bookl summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.

  2. Laser Raman Spectroscopy with Different Excitation Sources and Extension to Surface Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Md. Wahadoszamen

    2015-01-01

    Full Text Available A dispersive Raman spectrometer was used with three different excitation sources (Argon-ion, He-Ne, and Diode lasers operating at 514.5 nm, 633 nm, and 782 nm, resp.. The system was employed to a variety of Raman active compounds. Many of the compounds exhibit very strong fluorescence while being excited with a laser emitting at UV-VIS region, hereby imposing severe limitation to the detection efficiency of the particular Raman system. The Raman system with variable excitation laser sources provided us with a desired flexibility toward the suppression of unwanted fluorescence signal. With this Raman system, we could detect and specify the different vibrational modes of various hazardous organic compounds and some typical dyes (both fluorescent and nonfluorescent. We then compared those results with the ones reported in literature and found the deviation within the range of ±2 cm−1, which indicates reasonable accuracy and usability of the Raman system. Then, the surface enhancement technique of Raman spectrum was employed to the present system. To this end, we used chemically prepared colloidal suspension of silver nanoparticles as substrate and Rhodamine 6G as probe. We could observe significant enhancement of Raman signal from Rhodamine 6G using the colloidal solution of silver nanoparticles the average magnitude of which is estimated to be 103.

  3. Surface-enhanced Raman effect in hybrid metal–semiconductor nanoparticle assemblies

    International Nuclear Information System (INIS)

    Lughi, Vanni; Bonifacio, Alois; Barbone, Matteo; Marsich, Lucia; Sergo, Valter

    2013-01-01

    Hybrid metal–semiconductor nanoparticles consisting of silver nanoparticle cores (AgNPs) coated with a layer of CdSe quantum dots (QDs) have been studied by Raman spectroscopy. The hybrid nanoparticles were prepared via electrostatic interaction by mixing aqueous suspensions of QDs and AgNPs, where opposite charges on the AgNPs and QDs surfaces were induced by opportunely selected capping agents. Assemblies of such hybrid nanoparticles show an increased intensity of the Raman spectrum of up to 500 times, when compared to that of the sole QDs. This enhancement is attributed to the SERS effect (Surface-enhanced Raman scattering). Such enhancement of the Raman modes suggests several opportunities for further research, both in imaging and sensing applications.

  4. Enhancement of Raman scattering from monolayer graphene by photonic crystal nanocavities

    Science.gov (United States)

    Kimura, Issei; Yoshida, Masahiro; Sota, Masaki; Inoue, Taiki; Chiashi, Shohei; Maruyama, Shigeo; Kato, Yuichiro K.

    Monolayer graphene is an atomically thin two-dimensional material that shows strong Raman scattering, while photonic crystal nanocavities with small mode volumes allow for efficient optical coupling at the nanoscale. Here we demonstrate resonant enhancement of graphene Raman G' band by coupling to photonic crystal cavity modes. Hexagonal-lattice photonic crystal L3 cavities are fabricated from silicon-on-insulator substrates. and monolayer graphene sheets grown by chemical vapor deposition are transferred onto the nanocavities. Excitation wavelength dependence of Raman spectra show that the Raman intensity is enhanced when the G' peak is in resonance with the cavity mode. By performing imaging measurements, we confirm that such an enhancement is only observed at the cavity position. Work supported by JSPS KAKENHI Grant Numbers JP16K13613, JP25107002 and MEXT (Photon Frontier Network Program, Nanotechnology Platform).

  5. Surface-enhanced Raman scattering on gold nanotrenches and nanoholes

    KAUST Repository

    Yue, Weisheng; Yang, Yang; Wang, Zhihong; Chen, Longqing; Wong, Ka Chun; Syed, Ahad A.; Chen, Zong; Wang, Xianbin

    2012-01-01

    Dependent effects on edge-to-edge distance and incidence polarization in surface-enhanced Raman Scattering (SERS) were studied in detection of 4-mercaptopyridine (4-MPy) molecules absorbed on gold nanotrenches and nanoholes. The gold nanostructures

  6. Preparation of surface enhanced Raman substrate and its characterization

    Science.gov (United States)

    Liu, Y.; Wang, J. Y.; Wang, J. Q.

    2017-10-01

    Surface enhanced Raman spectroscopy (SERS) is a fast, convenient and highly sensitive detection technique, and preparing the good effect and repeatable substrate is the key to realize the trace amount and quantitative detection in the field of food safety detection. In this paper, a surface enhanced Raman substrate based on submicrometer silver particles structure was prepared by chemical deposition method, and characterized its structure and optical properties.

  7. Charge Transfer Effect on Raman and Surface Enhanced Raman Spectroscopy of Furfural Molecules.

    Science.gov (United States)

    Wan, Fu; Shi, Haiyang; Chen, Weigen; Gu, Zhaoliang; Du, Lingling; Wang, Pinyi; Wang, Jianxin; Huang, Yingzhou

    2017-08-02

    The detection of furfural in transformer oil through surface enhanced Raman spectroscopy (SERS) is one of the most promising online monitoring techniques in the process of transformer aging. In this work, the Raman of individual furfural molecules and SERS of furfural-M x (M = Ag, Au, Cu) complexes are investigated through density functional theory (DFT). In the Raman spectrum of individual furfural molecules, the vibration mode of each Raman peak is figured out, and the deviation from experimental data is analyzed by surface charge distribution. In the SERS of furfural-M x complexes, the influence of atom number and species on SERS chemical enhancement factors (EFs) are studied, and are further analyzed by charge transfer effect. Our studies strengthen the understanding of charge transfer effect in the SERS of furfural molecules, which is important in the online monitoring of the transformer aging process through SERS.

  8. Surface enhanced raman spectroscopy analytical, biophysical and life science applications

    CERN Document Server

    Schlücker, Sebastian

    2013-01-01

    Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.

  9. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic...

  10. Dynamic optical bistability in resonantly enhanced Raman generation

    International Nuclear Information System (INIS)

    Novikova, I.; Phillips, D.F.; Zibrov, A.S.; Andre, A.; Walsworth, R.L.

    2004-01-01

    We report observations of novel dynamic behavior in resonantly enhanced stimulated Raman scattering in Rb vapor. In particular, we demonstrate a dynamic hysteresis of the Raman scattered optical field in response to changes of the drive laser field intensity and/or frequency. This effect may be described as a dynamic form of optical bistability resulting from the formation and decay of atomic coherence. We have applied this phenomenon to the realization of an all-optical switch

  11. A novel non-imaging optics based Raman spectroscopy device for transdermal blood analyte measurement

    Directory of Open Access Journals (Sweden)

    Chae-Ryon Kong

    2011-09-01

    Full Text Available Due to its high chemical specificity, Raman spectroscopy has been considered to be a promising technique for non-invasive disease diagnosis. However, during Raman excitation, less than one out of a million photons undergo spontaneous Raman scattering and such weakness in Raman scattered light often require highly efficient collection of Raman scattered light for the analysis of biological tissues. We present a novel non-imaging optics based portable Raman spectroscopy instrument designed for enhanced light collection. While the instrument was demonstrated on transdermal blood glucose measurement, it can also be used for detection of other clinically relevant blood analytes such as creatinine, urea and cholesterol, as well as other tissue diagnosis applications. For enhanced light collection, a non-imaging optical element called compound hyperbolic concentrator (CHC converts the wide angular range of scattered photons (numerical aperture (NA of 1.0 from the tissue into a limited range of angles accommodated by the acceptance angles of the collection system (e.g., an optical fiber with NA of 0.22. A CHC enables collimation of scattered light directions to within extremely narrow range of angles while also maintaining practical physical dimensions. Such a design allows for the development of a very efficient and compact spectroscopy system for analyzing highly scattering biological tissues. Using the CHC-based portable Raman instrument in a clinical research setting, we demonstrate successful transdermal blood glucose predictions in human subjects undergoing oral glucose tolerance tests.

  12. Theoretical studies of surface enhanced hyper-Raman spectroscopy: The chemical enhancement mechanism

    Science.gov (United States)

    Valley, Nicholas; Jensen, Lasse; Autschbach, Jochen; Schatz, George C.

    2010-08-01

    Hyper-Raman spectra for pyridine and pyridine on the surface of a tetrahedral 20 silver atom cluster are calculated using static hyperpolarizability derivatives obtained from time dependent density functional theory. The stability of the results with respect to choice of exchange-correlation functional and basis set is verified by comparison with experiment and with Raman spectra calculated for the same systems using the same methods. Calculated Raman spectra were found to match well with experiment and previous theoretical calculations. The calculated normal and surface enhanced hyper-Raman spectra closely match experimental results. The chemical enhancement factors for hyper-Raman are generally larger than for Raman (102-104 versus 101-102). Integrated hyper-Raman chemical enhancement factors are presented for a set of substituted pyridines. A two-state model is developed to predict these chemical enhancement factors and this was found to work well for the majority of the molecules considered, providing a rationalization for the difference between hyper-Raman and Raman enhancement factors.

  13. Enhanced optical coupling and Raman scattering via microscopic interface engineering

    Science.gov (United States)

    Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

    2017-11-01

    Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

  14. Enhanced noise and Raman scattering in plasma

    International Nuclear Information System (INIS)

    Simon, A.; Short, R.W.

    1987-04-01

    Observations of Raman scattering from laser-produced plasma have shown a number of puzzling features. These can be explained by assuming the presence of a bump-on-tail electron distribution created by pulses of fast electrons arising from instabilities at the critical (n/sub c/) or the quarter-critical (n/sub c//4) surface. Experiments using thin foils, in which the target density drops below n/sub c/ and even n/sub c//4 early in the laser pulse, have continued to show the same agreement as is seen for thick targets between the observed Raman spectrum and the predictions of this theory. This raises the issue of the time scale on which such directed pulses of fast electrons can continue to exist in the plasma after their source at n/sub c/ or n/sub c//4 disappears. We show that the classical degradation process is quite slow (of the order of 100 ps or more). Collective processes would appear to broaden and flatten the beam on a faster time scale. However, inclusion of finite spatial size strongly reduces the effect. Furthermore, we will show that broadening of the beam has little effect on the predicted spectrum

  15. Time-lapse Raman imaging of osteoblast differentiation

    Science.gov (United States)

    Hashimoto, Aya; Yamaguchi, Yoshinori; Chiu, Liang-Da; Morimoto, Chiaki; Fujita, Katsumasa; Takedachi, Masahide; Kawata, Satoshi; Murakami, Shinya; Tamiya, Eiichi

    2015-07-01

    Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable.

  16. Applications of the surface enhanced Raman scattering (SERS)

    International Nuclear Information System (INIS)

    Picquart, M.; Haro P, E.; Bernard, S.

    2007-01-01

    Full text: Vibration spectroscopy techniques are used for many times to identify substances, determine molecular structure and quantify them, independently of their physical state. Raman spectroscopy as infrared absorption permit to access the vibration energy levels of molecules. In the second case, the permanent dipolar moment is involved while in the first one it is the polarizability (and the induced dipolar moment). Unfortunately, the classical Raman spectroscopy is low sensitive in particular in the case of biological molecules. On the opposite, the surface enhanced Raman spectroscopy (SERS) offers great potentialities. In this case, the molecules are adsorbed on a rough surface or on nanoparticles of gold or silver and the: signal can be increased by a factor of 10 7 to 10 8 . Moreover, the spectral enhancement is greater for the vibrations of the functional group of the molecule adsorbed on the substrate. In this work, we present the main theoretical bases of SERS, and some results obtain on different systems. (Author)

  17. Surface-enhanced Raman scattering from silver electrodes

    International Nuclear Information System (INIS)

    Trott, G.R.

    1982-01-01

    The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process

  18. Engineering Plasmonic Nanopillar Arrays for Surface-enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wu, Kaiyu

    This Ph.D. thesis presents (i) an in-depth understanding of the localized surface plasmon resonances (LSPRs) in the nanopillar arrays (NPs) for surface-enhanced Raman spectroscopy (SERS), and (ii) systematic ways of optimizing the fabrication process of NPs to improve their SERS efficiencies. Thi...

  19. Physical chemistry of Nanogap-Enhanced Raman Scattering (NERS)

    Science.gov (United States)

    Suh, Yung Doug; Kim, Hyun Woo

    2017-08-01

    Plasmonically coupled electromagnetic field localization has generated a variety of new concepts and applications, and this has been one of the hottest topics in nanoscience, materials science, chemistry, physics and engineering and increasingly more important over the last decade. In particular, plasmonically coupled nanostructures with ultra-small gap ( 1-nm or smaller) gap have been of special interest due to their ultra-strong optical properties that can be useful for a variety of signal enhancements such surface-enhanced Raman scattering (SERS) and nanoantenna. These promising nanostructures with extraordinarily strong optical signal, however, have rendered a limited success in widespread use and commercialization largely due to the lack of designing principles, high-yield synthetic strategies with nm-level structural controllability and reproducibility and lack of systematic single-molecule and single-particle level studies. All these are extremely important challenges because even small changes ( 1 nm) of the coupled nanogap structures can significant affect plasmon mode and signal intensity and therefore structural and signal reproducibility and controllability can be in question. The plasmonic nanogap-enhanced Raman scattering (NERS) is defined as the plasmonic nanogap-based Raman signal enhancement within plasmonic nanogap particles with 1 nm gap and a Raman dye positioned inside the gap.

  20. Novel strategies of Raman imaging for brain tumor research.

    Science.gov (United States)

    Anna, Imiela; Bartosz, Polis; Lech, Polis; Halina, Abramczyk

    2017-10-17

    Raman diagnostics and imaging have been shown to be an effective tool for the analysis and discrimination of human brain tumors from normal structures. Raman spectroscopic methods have potential to be applied in clinical practice as they allow for identification of tumor margins during surgery. In this study, we investigate medulloblastoma (grade IV WHO) (n= 5), low-grade astrocytoma (grades I-II WHO) (n =4), ependymoma (n=3) and metastatic brain tumors (n= 1) and the tissue from the negative margins used as normal controls. We compare a high grade medulloblastoma, low grade astrocytoma and non-tumor samples from human central nervous system (CNS) tissue. Based on the properties of the Raman vibrational features and Raman images we provide a real-time feedback method that is label-free to monitor tumor metabolism that reveals reprogramming of biosynthesis of lipids, proteins, DNA and RNA. Our results indicate marked metabolic differences between low and high grade brain tumors. We discuss molecular mechanisms causing these metabolic changes, particularly lipid alterations in malignant medulloblastoma and low grade gliomas that may shed light on the mechanisms driving tumor recurrence thereby revealing new approaches for the treatment of malignant glioma. We have found that the high-grade tumors of central nervous system (medulloblastoma) exhibit enhanced level of β-sheet conformation and down-regulated level of α-helix conformation when comparing against normal tissue. We have found that almost all tumors studied in the paper have increased Raman signals of nucleic acids. This increase can be interpreted as increased DNA/RNA turnover in brain tumors. We have shown that the ratio of Raman intensities I 2930 /I 2845 at 2930 and 2845 cm -1 is a good source of information on the ratio of lipid and protein contents. We have found that the ratio reflects the different lipid and protein contents of cancerous brain tissue compared to the non-tumor tissue. We found that

  1. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  2. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

    2015-11-03

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  3. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2015-07-14

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  4. Sparse-sampling with time-encoded (TICO) stimulated Raman scattering for fast image acquisition

    Science.gov (United States)

    Hakert, Hubertus; Eibl, Matthias; Karpf, Sebastian; Huber, Robert

    2017-07-01

    Modern biomedical imaging modalities aim to provide researchers a multimodal contrast for a deeper insight into a specimen under investigation. A very promising technique is stimulated Raman scattering (SRS) microscopy, which can unveil the chemical composition of a sample with a very high specificity. Although the signal intensities are enhanced manifold to achieve a faster acquisition of images if compared to standard Raman microscopy, there is a trade-off between specificity and acquisition speed. Commonly used SRS concepts either probe only very few Raman transitions as the tuning of the applied laser sources is complicated or record whole spectra with a spectrometer based setup. While the first approach is fast, it reduces the specificity and the spectrometer approach records whole spectra -with energy differences where no Raman information is present-, which limits the acquisition speed. Therefore, we present a new approach based on the TICO-Raman concept, which we call sparse-sampling. The TICO-sparse-sampling setup is fully electronically controllable and allows probing of only the characteristic peaks of a Raman spectrum instead of always acquiring a whole spectrum. By reducing the spectral points to the relevant peaks, the acquisition time can be greatly reduced compared to a uniformly, equidistantly sampled Raman spectrum while the specificity and the signal to noise ratio (SNR) are maintained. Furthermore, all laser sources are completely fiber based. The synchronized detection enables a full resolution of the Raman signal, whereas the analogue and digital balancing allows shot noise limited detection. First imaging results with polystyrene (PS) and polymethylmethacrylate (PMMA) beads confirm the advantages of TICO sparse-sampling. We achieved a pixel dwell time as low as 35 μs for an image differentiating both species. The mechanical properties of the applied voice coil stage for scanning the sample currently limits even faster acquisition.

  5. Reversibility of Graphene-Enhanced Raman Scattering with Fluorinated Graphene

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Melníková Komínková, Zuzana; Verhagen, Timotheus; Vejpravová, Jana; Kalbáč, Martin

    2017-01-01

    Roč. 254, č. 11 (2017), č. článku 1700177. ISSN 0370-1972 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : fluorination * graphene * graphene-enhanced Raman * Raman spectroscopy * scattering Subject RIV: CF - Physical ; Theoretical Chemistry; BM - Solid Matter Physics ; Magnetism (FZU-D) OBOR OECD: Physical chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D) Impact factor: 1.674, year: 2016

  6. [Current views on surface enhanced Raman spectroscopy in microbiology].

    Science.gov (United States)

    Jia, Xiaoxiao; Li, Jing; Qin, Tian; Deng, Aihua; Liu, Wenjun

    2015-05-01

    Raman spectroscopy has generated many branches during the development for more than 90 years. Surface enhanced Raman spectroscopy (SERS) improves SNR by using the interaction between tested materials and the surface of rough metal, as to quickly get higher sensitivity and precision spectroscopy without sample pretreatment. This article describes the characteristic and classification of SERS, and updates the theory and clinical application of SERS. It also summarizes the present status and progress of SERS in various disciplines and illustrates the necessity and urgency of its research, which provides rationale for the application for SERS in microbiology.

  7. Dental caries imaging using hyperspectral stimulated Raman scattering microscopy

    Science.gov (United States)

    Wang, Zi; Zheng, Wei; Jian, Lin; Huang, Zhiwei

    2016-03-01

    We report the development of a polarization-resolved hyperspectral stimulated Raman scattering (SRS) imaging technique based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of dental caries. In our imaging system, hyperspectral SRS images (512×512 pixels) in both fingerprint region (800-1800 cm-1) and high-wavenumber region (2800-3600 cm-1) are acquired in minutes by scanning the wavelength of OPO output, which is a thousand times faster than conventional confocal micro Raman imaging. SRS spectra variations from normal enamel to caries obtained from the hyperspectral SRS images show the loss of phosphate and carbonate in the carious region. While polarization-resolved SRS images at 959 cm-1 demonstrate that the caries has higher depolarization ratio. Our results demonstrate that the polarization resolved-hyperspectral SRS imaging technique developed allows for rapid identification of the biochemical and structural changes of dental caries.

  8. Role of Raman spectroscopy and surface enhanced Raman spectroscopy in colorectal cancer

    Science.gov (United States)

    Jenkins, Cerys A; Lewis, Paul D; Dunstan, Peter R; Harris, Dean A

    2016-01-01

    Colorectal cancer (CRC) is the fourth most common cancer in the United Kingdom and is the second largest cause of cancer related death in the United Kingdom after lung cancer. Currently in the United Kingdom there is not a diagnostic test that has sufficient differentiation between patients with cancer and those without cancer so the current referral system relies on symptomatic presentation in a primary care setting. Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) are forms of vibrational spectroscopy that offer a non-destructive method to gain molecular information about biological samples. The techniques offer a wide range of applications from in vivo or in vitro diagnostics using endoscopic probes, to the use of micro-spectrometers for analysis of biofluids. The techniques have the potential to detect molecular changes prior to any morphological changes occurring in the tissue and therefore could offer many possibilities to aid the detection of CRC. The purpose of this review is to look at the current state of diagnostic technology in the United Kingdom. The development of Raman spectroscopy and SERS in clinical applications relation for CRC will then be discussed. Finally, future areas of research of Raman/SERS as a clinical tool for the diagnosis of CRC are also discussed. PMID:27190582

  9. Plasmonic Colloidal Nanoantennas for Tip-Enhanced Raman Spectrocopy

    Science.gov (United States)

    Dill, Tyler J.

    Plasmonic nanoantennas that a support localized surface plasmon resonance (LSPR) are capable of confining visible light to subwavelength dimensions due to strong electromagnetic field enhancement at the probe tip. Nanoantenna enable optical methods such as tip-enhanced Raman spectroscopy (TERS), a technique that uses scanning probe microscopy tips to provide chemical information with nanoscale spatial resolution and single-molecule sensitivities. The LSPR supported by the probe tip is extremely sensitive to the nanoscale morphology of the nanoantenna. Control of nanoscale morphology is notoriously difficult to achieve, resulting in TERS probes with poor reproducibility. In my thesis, I demonstrate high-performance, predictable, and broadband nanospectroscopy probes that are fabricated by self-assembly. Shaped metal nanoparticles are organized into dense layers and deposited onto scanning probe tips. When coupled to a metal substrate, these probes support a strong optical resonance in the gap between the substrate and the probe, producing dramatic field enhancements. I show through experiment and electromagnetic modeling that close-packed but electrically isolated nanoparticles are electromagnetically coupled. Hybridized LSPRs supported by self-assembled nanoparticles with a broadband optical response, giving colloidal nanoantenna a high tolerance for geometric variation resulting from fabrication. I find that coupled nanoparticles act as a waveguide, transferring energy from many neighboring nanoparticles towards the active TERS apex. I also use surface-enhanced Raman spectroscopy (SERS) to characterize the effects of nanoparticle polydispersity and gap height on the Raman enhancement. These colloidal probes have consistently achieved dramatic Raman enhancements in the range of 108-109 with sub-50 nm spatial resolution. Furthermore, in contrast to other nanospectroscopy probes, these colloidal probes can be fabricated in a scalable fashion with a batch

  10. Raman spectroscopy and imaging: applications in human breast cancer diagnosis.

    Science.gov (United States)

    Brozek-Pluska, Beata; Musial, Jacek; Kordek, Radzislaw; Bailo, Elena; Dieing, Thomas; Abramczyk, Halina

    2012-08-21

    The applications of spectroscopic methods in cancer detection open new possibilities in early stage diagnostics. Raman spectroscopy and Raman imaging represent novel and rapidly developing tools in cancer diagnosis. In the study described in this paper Raman spectroscopy has been employed to examine noncancerous and cancerous human breast tissues of the same patient. The most significant differences between noncancerous and cancerous tissues were found in regions characteristic for the vibrations of carotenoids, lipids and proteins. Particular attention was paid to the role played by unsaturated fatty acids in the differentiation between the noncancerous and the cancerous tissues. Comparison of Raman spectra of the noncancerous and the cancerous tissues with the spectra of oleic, linoleic, α-linolenic, γ-linolenic, docosahexaenoic and eicosapentaenoic acids has been presented. The role of sample preparation in the determination of cancer markers is also discussed in this study.

  11. Highly Enhanced Raman Scattering on Carbonized Polymer Films.

    Science.gov (United States)

    Yoon, Jong-Chul; Hwang, Jongha; Thiyagarajan, Pradheep; Ruoff, Rodney S; Jang, Ji-Hyun

    2017-06-28

    We have discovered a carbonized polymer film to be a reliable and durable carbon-based substrate for carbon enhanced Raman scattering (CERS). Commercially available SU8 was spin coated and carbonized (c-SU8) to yield a film optimized to have a favorable Fermi level position for efficient charge transfer, which results in a significant Raman scattering enhancement under mild measurement conditions. A highly sensitive CERS (detection limit of 10 -8 M) that was uniform over a large area was achieved on a patterned c-SU8 film and the Raman signal intensity has remained constant for 2 years. This approach works not only for the CMOS-compatible c-SU8 film but for any carbonized film with the correct composition and Fermi level, as demonstrated with carbonized-PVA (poly(vinyl alcohol)) and carbonized-PVP (polyvinylpyrollidone) films. Our study certainly expands the rather narrow range of Raman-active material platforms to include robust carbon-based films readily obtained from polymer precursors. As it uses broadly applicable and cheap polymers, it could offer great advantages in the development of practical devices for chemical/bio analysis and sensors.

  12. Label-Free Raman Imaging to Monitor Breast Tumor Signatures.

    Science.gov (United States)

    Manciu, Felicia S; Ciubuc, John D; Parra, Karla; Manciu, Marian; Bennet, Kevin E; Valenzuela, Paloma; Sundin, Emma M; Durrer, William G; Reza, Luis; Francia, Giulio

    2017-08-01

    Although not yet ready for clinical application, methods based on Raman spectroscopy have shown significant potential in identifying, characterizing, and discriminating between noncancerous and cancerous specimens. Real-time and accurate medical diagnosis achievable through this vibrational optical method largely benefits from improvements in current technological and software capabilities. Not only is the acquisition of spectral information now possible in milliseconds and analysis of hundreds of thousands of data points achieved in minutes, but Raman spectroscopy also allows simultaneous detection and monitoring of several biological components. Besides demonstrating a significant Raman signature distinction between nontumorigenic (MCF-10A) and tumorigenic (MCF-7) breast epithelial cells, our study demonstrates that Raman can be used as a label-free method to evaluate epidermal growth factor activity in tumor cells. Comparative Raman profiles and images of specimens in the presence or absence of epidermal growth factor show important differences in regions attributed to lipid, protein, and nucleic acid vibrations. The occurrence, which is dependent on the presence of epidermal growth factor, of new Raman features associated with the appearance of phosphothreonine and phosphoserine residues reflects a signal transduction from the membrane to the nucleus, with concomitant modification of DNA/RNA structural characteristics. Parallel Western blotting analysis reveals an epidermal growth factor induction of phosphorylated Akt protein, corroborating the Raman results. The analysis presented in this work is an important step toward Raman-based evaluation of biological activity of epidermal growth factor receptors on the surfaces of breast cancer cells. With the ultimate future goal of clinically implementing Raman-guided techniques for the diagnosis of breast tumors (e.g., with regard to specific receptor activity), the current results just lay the foundation for

  13. Plasmonic nanostructures for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Jiang, Ruiqian

    In the last three decades, a large number of different plasmonic nanostructures have attracted much attention due to their unique optical properties. Those plasmonic nanostructures include nanoparticles, nanoholes and metal nanovoids. They have been widely utilized in optical devices and sensors. When the plasmonic nanostructures interact with the electromagnetic wave and their surface plasmon frequency match with the light frequency, the electrons in plasmonic nanostructures will resonate with the same oscillation as incident light. In this case, the plasmonic nanostructures can absorb light and enhance the light scattering. Therefore, the plasmonic nanostructures can be used as substrate for surface-enhanced Raman spectroscopy to enhance the Raman signal. Using plasmonic nanostructures can significantly enhance Raman scattering of molecules with very low concentrations. In this thesis, two different plasmonic nanostructures Ag dendrites and Au/Ag core-shell nanoparticles are investigated. Simple methods were used to produce these two plasmonic nanostructures. Then, their applications in surface enhanced Raman scattering have been explored. Ag dendrites were produced by galvanic replacement reaction, which was conducted using Ag nitrate aqueous solution and copper metal. Metal copper layer was deposited at the bottom side of anodic aluminum oxide (AAO) membrane. Silver wires formed inside AAO channels connected Ag nitrate on the top of AAO membrane and copper layer at the bottom side of AAO. Silver dendrites were formed on the top side of AAO. The second plasmonic nanostructure is Au/Ag core-shell nanoparticles. They were fabricated by electroless plating (galvanic replacement) reaction in a silver plating solution. First, electrochemically evolved hydrogen bubbles were used as template through electroless deposition to produce hollow Au nanoparticles. Then, the Au nanoparticles were coated with Cu shells in a Cu plating solution. In the following step, a Ag

  14. Aligned gold nanoneedle arrays for surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Yang Yong; Huang Zhengren; Jiang Dongliang; Tanemura, Masaki; Yamaguchi, Kohei; Li Zhiyuan; Huang Yingping; Kawamura, Go; Nogami, Masayuki

    2010-01-01

    A simple Ar + -ion irradiation route has been developed to prepare gold nanoneedle arrays on glass substrates for surface-enhanced Raman scattering (SERS)-active substrates. The nanoneedles exhibited very sharp tips with an apex diameter of 20 nm. These arrays were evaluated as potential SERS substrates using malachite green molecules and exhibited a SERS enhancement factor of greater than 10 8 , which is attributed to the localized electron field enhancement around the apex of the needle and the surface plasmon coupling originating from the periodic structure. This work demonstrates a new technique for producing controllable and reproducible SERS substrates potentially applicable for chemical and biological assays.

  15. Towards eye-safe standoff Raman imaging systems

    Science.gov (United States)

    Glimtoft, Martin; Bââth, Petra; Saari, Heikki; Mäkynen, Jussi; Näsilä, Antti; Östmark, Henric

    2014-05-01

    Standoff Raman imaging systems have shown the ability to detect single explosives particles. However, in many cases, the laser intensities needed restrict the applications where they can be safely used. A new generation imaging Raman system has been developed based on a 355 nm UV laser that, in addition to eye safety, allows discrete and invisible measurements. Non-dangerous exposure levels for the eye are several orders of magnitude higher in UVA than in the visible range that previously has been used. The UV Raman system has been built based on an UV Fabry-Perot Interferometer (UV-FPI) developed by VTT. The design allows for precise selection of Raman shifts in combination with high out-of-band blocking. The stable operation of the UV-FPI module under varying environmental conditions is arranged by controlling the temperature of the module and using a closed loop control of the FPI air gap based on capacitive measurement. The system presented consists of a 3rd harmonics Nd:YAG laser with 1.5 W average output at 1000 Hz, a 200 mm Schmidt-Cassegrain telescope, UV-FPI filter and an ICCD camera for signal gating and detection. The design principal leads to a Raman spectrum in each image pixel. The system is designed for field use and easy manoeuvring. Preliminary results show that in measurements of <60 s on 10 m distance, single AN particles of <300 μm diameter can be identified.

  16. Surface-Enhanced Raman Spectroscopy Integrated Centrifugal Microfluidics Platform

    DEFF Research Database (Denmark)

    Durucan, Onur

    This PhD thesis demonstrates (i) centrifugal microfluidics disc platform integrated with Au capped nanopillar (NP) substrates for surface-enhanced Raman spectroscopy (SERS) based sensing, and (ii) novel sample analysis concepts achieved by synergistical combination of sensing techniques and minia......This PhD thesis demonstrates (i) centrifugal microfluidics disc platform integrated with Au capped nanopillar (NP) substrates for surface-enhanced Raman spectroscopy (SERS) based sensing, and (ii) novel sample analysis concepts achieved by synergistical combination of sensing techniques...... dense array of NP structures. Furthermore, the wicking assisted nanofiltration procedure was accomplished in centrifugal microfluidics platform and as a result additional sample purification was achieved through the centrifugation process. In this way, the Au coated NP substrate was utilized...

  17. Cavity-Enhanced Raman Spectroscopy for Food Chain Management

    Directory of Open Access Journals (Sweden)

    Vincenz Sandfort

    2018-02-01

    Full Text Available Comprehensive food chain management requires the monitoring of many parameters including temperature, humidity, and multiple gases. The latter is highly challenging because no low-cost technology for the simultaneous chemical analysis of multiple gaseous components currently exists. This contribution proposes the use of cavity enhanced Raman spectroscopy to enable online monitoring of all relevant components using a single laser source. A laboratory scale setup is presented and characterized in detail. Power enhancement of the pump light is achieved in an optical resonator with a Finesse exceeding 2500. A simulation for the light scattering behavior shows the influence of polarization on the spatial distribution of the Raman scattered light. The setup is also used to measure three relevant showcase gases to demonstrate the feasibility of the approach, including carbon dioxide, oxygen and ethene.

  18. Surface-enhanced Raman spectroscopy bioanalytical, biomolecular and medical applications

    CERN Document Server

    Procházka, Marek

    2016-01-01

    This book gives an overview of recent developments in RS and SERS for sensing and biosensing considering also limitations, possibilities and prospects of this technique. Raman scattering (RS) is a widely used vibrational technique providing highly specific molecular spectral patterns. A severe limitation for the application of this spectroscopic technique lies in the low cross section of RS. Surface-enhanced Raman scattering (SERS) spectroscopy overcomes this problem by 6-11 orders of magnitude enhancement compared with the standard RS for molecules in the close vicinity of certain rough metal surfaces. Thus, SERS combines molecular fingerprint specificity with potential single-molecule sensitivity. Due to the recent development of new SERS-active substrates, labeling and derivatization chemistry as well as new instrumentations, SERS became a very promising tool for many varied applications, including bioanalytical studies and sensing. Both intrinsic and extrinsic SERS biosensing schemes have been employed to...

  19. [Study on the surface-enhanced Raman spectrum of trimethoprim].

    Science.gov (United States)

    Zhang, Jin-zhi; Wang, Yuan

    2003-02-01

    A new method is given in this paper to study the spectra of trimethoprim by using the surface-enhanced Raman spectrum (SERS) technology and the highly efficient thin layer chromatography (TLC) dissociation technology. The results of SERS indicate that the main vibrant spectral band can be obtained by TLC in the samples of about 6 micrograms. The expansion and contraction of pyrimidine ring can be obviously increased and the molecule information can be exactly presented under the action of silver particles.

  20. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

    2010-01-01

    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  1. Cell Imaging by Spontaneous and Amplified Raman Spectroscopies

    Directory of Open Access Journals (Sweden)

    Giulia Rusciano

    2017-01-01

    Full Text Available Raman spectroscopy (RS is a powerful, noninvasive optical technique able to detect vibrational modes of chemical bonds. The high chemical specificity due to its fingerprinting character and the minimal requests for sample preparation have rendered it nowadays very popular in the analysis of biosystems for diagnostic purposes. In this paper, we first discuss the main advantages of spontaneous RS by describing the study of a single protozoan (Acanthamoeba, which plays an important role in a severe ophthalmological disease (Acanthamoeba keratitis. Later on, we point out that the weak signals that originated from Raman scattering do not allow probing optically thin samples, such as cellular membrane. Experimental approaches able to overcome this drawback are based on the use of metallic nanostructures, which lead to a huge amplification of the Raman yields thanks to the excitation of localized surface plasmon resonances. Surface-enhanced Raman scattering (SERS and tip-enhanced Raman scattering (TERS are examples of such innovative techniques, in which metallic nanostructures are assembled on a flat surface or on the tip of a scanning probe microscope, respectively. Herein, we provide a couple of examples (red blood cells and bacterial spores aimed at studying cell membranes with these techniques.

  2. Exploring the chemical enhancement for surface-enhanced Raman scattering with Au bowtie nanoantennas

    International Nuclear Information System (INIS)

    Fromm, David P.; Sundaramurthy, Arvind; Kinkhabwala, Anika; Schuck, P. James; Kino, Gordon S.; Moerner, W.E.

    2006-01-01

    Single metallic bowtie nanoantennas provide a controllable environment for surface-enhanced Raman scattering (SERS) of adsorbed molecules. Bowties have experimentally measured electromagnetic enhancements, enabling estimation of chemical enhancement for both the bulk and the few-molecule regime. Strong fluctuations of selected Raman lines imply that a small number of p-mercaptoaniline molecules on a single bowtie show chemical enhancement >10 7 , much larger than previously believed, likely due to charge transfer between the Au surface and the molecule. This chemical sensitivity of SERS has significant implications for ultra-sensitive detection of single molecules

  3. Surface enhanced Raman spectroscopy on a flat graphene surface

    Science.gov (United States)

    Xu, Weigao; Ling, Xi; Xiao, Jiaqi; Dresselhaus, Mildred S.; Kong, Jing; Xu, Hongxing; Liu, Zhongfan; Zhang, Jin

    2012-01-01

    Surface enhanced Raman spectroscopy (SERS) is an attractive analytical technique, which enables single-molecule sensitive detection and provides its special chemical fingerprints. During the past decades, researchers have made great efforts towards an ideal SERS substrate, mainly including pioneering works on the preparation of uniform metal nanostructure arrays by various nanoassembly and nanotailoring methods, which give better uniformity and reproducibility. Recently, nanoparticles coated with an inert shell were used to make the enhanced Raman signals cleaner. By depositing SERS-active metal nanoislands on an atomically flat graphene layer, here we designed a new kind of SERS substrate referred to as a graphene-mediated SERS (G-SERS) substrate. In the graphene/metal combined structure, the electromagnetic “hot” spots (which is the origin of a huge SERS enhancement) created by the gapped metal nanoislands through the localized surface plasmon resonance effect are supposed to pass through the monolayer graphene, resulting in an atomically flat hot surface for Raman enhancement. Signals from a G-SERS substrate were also demonstrated to have interesting advantages over normal SERS, in terms of cleaner vibrational information free from various metal-molecule interactions and being more stable against photo-induced damage, but with a comparable enhancement factor. Furthermore, we demonstrate the use of a freestanding, transparent and flexible “G-SERS tape” (consisting of a polymer-layer-supported monolayer graphene with sandwiched metal nanoislands) to enable direct, real time and reliable detection of trace amounts of analytes in various systems, which imparts high efficiency and universality of analyses with G-SERS substrates. PMID:22623525

  4. Surface-Enhanced Raman Scattering in Molecular Junctions.

    Science.gov (United States)

    Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

    2017-08-18

    Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

  5. Note: A portable Raman analyzer for microfluidic chips based on a dichroic beam splitter for integration of imaging and signal collection light paths

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yijia; Xu, Shuping; Xu, Weiqing, E-mail: xuwq@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012 (China); Chen, Lei [State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012 (China); College of Physics, Jilin University, Changchun 130012 (China); Chen, Gang [State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012 (China); College of Chemistry, Jilin University, Changchun 130012 (China); Bi, Wenbin [State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012 (China); School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Cui, Haining [College of Physics, Jilin University, Changchun 130012 (China)

    2015-05-15

    An integrated and portable Raman analyzer featuring an inverted probe fixed on a motor-driving adjustable optical module was designed for the combination of a microfluidic system. It possesses a micro-imaging function. The inverted configuration is advantageous to locate and focus microfluidic channels. Different from commercial micro-imaging Raman spectrometers using manual switchable light path, this analyzer adopts a dichroic beam splitter for both imaging and signal collection light paths, which avoids movable parts and improves the integration and stability of optics. Combined with surface-enhanced Raman scattering technique, this portable Raman micro-analyzer is promising as a powerful tool for microfluidic analytics.

  6. Raman characterization of high temperature materials using an imaging detector

    International Nuclear Information System (INIS)

    Rosenblatt, G.M.; Veirs, D.K.

    1989-03-01

    The characterization of materials by Raman spectroscopy has been advanced by recent technological developments in light detectors. Imaging photomultiplier-tube detectors are now available that impart position information in two dimensions while retaining photon-counting sensitivity, effectively greatly reducing noise. The combination of sensitivity and reduced noise allows smaller amounts of material to be analyzed. The ability to observe small amount of material when coupled with position information makes possible Raman characterization in which many spatial elements are analyzed simultaneously. Raman spectroscopy making use of these capabilities has been used, for instance, to analyze the phases present in carbon films and fibers and to map phase-transformed zones accompanying crack propagation in toughened zirconia ceramics. 16 refs., 6 figs., 2 tabs

  7. Development of a miRNA surface-enhanced Raman scattering assay using benchtop and handheld Raman systems.

    Science.gov (United States)

    Schechinger, Monika; Marks, Haley; Locke, Andrea; Choudhury, Mahua; Cote, Gerard

    2018-01-01

    DNA-functionalized nanoparticles, when paired with surface-enhanced Raman spectroscopy (SERS), can rapidly detect microRNA. However, widespread use of this approach is hindered by drawbacks associated with large and expensive benchtop Raman microscopes. MicroRNA-17 (miRNA-17) has emerged as a potential epigenetic indicator of preeclampsia, a condition that occurs during pregnancy. Biomarker detection using an SERS point-of-care device could enable prompt diagnosis and prevention as early as the first trimester. Recently, strides have been made in developing portable Raman systems for field applications. An SERS assay for miRNA-17 was assessed and translated from traditional benchtop Raman microscopes to a handheld system. Three different photoactive molecules were compared as potential Raman reporter molecules: a chromophore, malachite green isothiocyanate (MGITC), a fluorophore, tetramethylrhodamine isothiocyanate, and a polarizable small molecule 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB). For the benchtop Raman microscope, the DTNB-labeled assay yielded the greatest sensitivity under 532-nm laser excitation, but the MGITC-labeled assay prevailed at 785 nm. Conversely, DTNB was preferable for the miniaturized 785-nm Raman system. This comparison showed significant SERS enhancement variation in response to 1-nM miRNA-17, implying that the sensitivity of the assay may be more heavily dependent on the excitation wavelength, instrumentation, and Raman reporter chosen than on the plasmonic coupling from DNA/miRNA-mediated nanoparticle assemblies. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  8. Development of a miRNA surface-enhanced Raman scattering assay using benchtop and handheld Raman systems

    Science.gov (United States)

    Schechinger, Monika; Marks, Haley; Locke, Andrea; Choudhury, Mahua; Cote, Gerard

    2018-01-01

    DNA-functionalized nanoparticles, when paired with surface-enhanced Raman spectroscopy (SERS), can rapidly detect microRNA. However, widespread use of this approach is hindered by drawbacks associated with large and expensive benchtop Raman microscopes. MicroRNA-17 (miRNA-17) has emerged as a potential epigenetic indicator of preeclampsia, a condition that occurs during pregnancy. Biomarker detection using an SERS point-of-care device could enable prompt diagnosis and prevention as early as the first trimester. Recently, strides have been made in developing portable Raman systems for field applications. An SERS assay for miRNA-17 was assessed and translated from traditional benchtop Raman microscopes to a handheld system. Three different photoactive molecules were compared as potential Raman reporter molecules: a chromophore, malachite green isothiocyanate (MGITC), a fluorophore, tetramethylrhodamine isothiocyanate, and a polarizable small molecule 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB). For the benchtop Raman microscope, the DTNB-labeled assay yielded the greatest sensitivity under 532-nm laser excitation, but the MGITC-labeled assay prevailed at 785 nm. Conversely, DTNB was preferable for the miniaturized 785-nm Raman system. This comparison showed significant SERS enhancement variation in response to 1-nM miRNA-17, implying that the sensitivity of the assay may be more heavily dependent on the excitation wavelength, instrumentation, and Raman reporter chosen than on the plasmonic coupling from DNA/miRNA-mediated nanoparticle assemblies.

  9. Surface-enhanced Raman scattering on gold nanotrenches and nanoholes

    KAUST Repository

    Yue, Weisheng

    2012-04-01

    Dependent effects on edge-to-edge distance and incidence polarization in surface-enhanced Raman Scattering (SERS) were studied in detection of 4-mercaptopyridine (4-MPy) molecules absorbed on gold nanotrenches and nanoholes. The gold nanostructures with controllable size and period were fabricated using electron-beam lithography. Large SERS enhancement in detection of 4-MPy molecules on both nanostructred substrates was observed. The SERS enhancement increased exponentially with decrease of edge to-edge distance for both the nanotrenches and nanoholes while keeping the sizes of the nanotrenches and nanoholes unchanged. Investigation of polarization dependence showed that the SERS enhancement of nanotrenches was much more sensitive to the incidence polarizations than that of nanoholes. © 2012 American Scientific Publishers.

  10. Novel routes to electromagnetic enhancement and its characterisation in surface- and tip-enhanced Raman scattering.

    Science.gov (United States)

    Dawson, P; Frey, D; Kalathingal, V; Mehfuz, R; Mitra, J

    2017-12-04

    Quantitative understanding of the electromagnetic component in enhanced Raman spectroscopy is often difficult to achieve on account of the complex substrate structures utilised. We therefore turn to two structurally simple systems amenable to detailed modelling. The first is tip-enhanced Raman scattering under electron scanning tunnelling microscopy control (STM-TERS) where, appealing to understanding developed in the context of photon emission from STM, it is argued that the localised surface plasmon modes driving the Raman enhancement exist in the visible and near-infrared regime only by virtue of significant modification to the optical properties of the tip and sample metals (gold here). This is due to the strong dc field-induced (∼10 9 V m -1 ) non-linear corrections to the dielectric function of gold via the third order susceptibility term in the polarisation. Also, sub-5 nm spatial resolution is shown in the modelling. Secondly, we suggest a novel deployment of hybrid plasmonic waveguide modes in surface enhanced Raman scattering (HPWG-SERS). This delivers strong confinement of electromagnetic energy in a ∼10 nm oxide 'gap' between a high-index dielectric material of nanoscale width (a GaAs nanorod and a 100 nm Si slab are considered here) and a metal, yielding a monotonic variation in the Raman enhancement factor as a function of wavelength with no long-wavelength cut-off, both features that contrast with STM-TERS.

  11. Dynamic placement of plasmonic hotspots for super-resolution surface-enhanced Raman scattering.

    Science.gov (United States)

    Ertsgaard, Christopher T; McKoskey, Rachel M; Rich, Isabel S; Lindquist, Nathan C

    2014-10-28

    In this paper, we demonstrate dynamic placement of locally enhanced plasmonic fields using holographic laser illumination of a silver nanohole array. To visualize these focused "hotspots", the silver surface was coated with various biological samples for surface-enhanced Raman spectroscopy (SERS) imaging. Due to the large field enhancements, blinking behavior of the SERS hotspots was observed and processed using a stochastic optical reconstruction microscopy algorithm enabling super-resolution localization of the hotspots to within 10 nm. These hotspots were then shifted across the surface in subwavelength (hotspots. Using this technique, we also show that such subwavelength shifting and localization of plasmonic hotspots has potential for imaging applications. Interestingly, illuminating the surface with randomly shifting SERS hotspots was sufficient to completely fill in a wide field of view for super-resolution chemical imaging.

  12. Silicon Nitride Background in Nanophotonic Waveguide Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ashim Dhakal

    2017-02-01

    Full Text Available Recent studies have shown that evanescent Raman spectroscopy using a silicon nitride (SiN nanophotonic waveguide platform has higher signal enhancement when compared to free-space systems. However, signal-to-noise ratio from the waveguide at a low analyte concentration is constrained by the shot-noise from the background light originating from the waveguide itself. Hence, understanding the origin and properties of this waveguide background luminescence (WGBL is essential to developing mitigation strategies. Here, we identify the dominating component of the WGBL spectrum composed of a broad Raman scattering due to momentum selection-rule breaking in amorphous materials, and several peaks specific to molecules embedded in the core. We determine the maximum of the Raman scattering efficiency of the WGBL at room temperature for 785 nm excitation to be 4.5 ± 1 × 10−9 cm−1·sr−1, at a Stokes shift of 200 cm−1. This efficiency decreases monotonically for higher Stokes shifts. Additionally, we also demonstrate the use of slotted waveguides and quasi-transverse magnetic polarization as some mitigation strategies.

  13. Rapid surface enhanced Raman scattering detection method for chloramphenicol residues

    Science.gov (United States)

    Ji, Wei; Yao, Weirong

    2015-06-01

    Chloramphenicol (CAP) is a widely used amide alcohol antibiotics, which has been banned from using in food producing animals in many countries. In this study, surface enhanced Raman scattering (SERS) coupled with gold colloidal nanoparticles was used for the rapid analysis of CAP. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 3-21G(d) and 6-31G(d) basis sets to analyze the assignment of vibrations. Affirmatively, the theoretical Raman spectrum of CAP was in complete agreement with the experimental spectrum. They both exhibited three strong peaks characteristic of CAP at 1104 cm-1, 1344 cm-1, 1596 cm-1, which were used for rapid qualitative analysis of CAP residues in food samples. The use of SERS as a method for the measurements of CAP was explored by comparing use of different solvents, gold colloidal nanoparticles concentration and absorption time. The method of the detection limit was determined as 0.1 μg/mL using optimum conditions. The Raman peak at 1344 cm-1 was used as the index for quantitative analysis of CAP in food samples, with a linear correlation of R2 = 0.9802. Quantitative analysis of CAP residues in foods revealed that the SERS technique with gold colloidal nanoparticles was sensitive and of a good stability and linear correlation, and suited for rapid analysis of CAP residue in a variety of food samples.

  14. Raman molecular imaging of brain frozen tissue sections.

    Science.gov (United States)

    Kast, Rachel E; Auner, Gregory W; Rosenblum, Mark L; Mikkelsen, Tom; Yurgelevic, Sally M; Raghunathan, Aditya; Poisson, Laila M; Kalkanis, Steven N

    2014-10-01

    Raman spectroscopy provides a molecular signature of the region being studied. It is ideal for neurosurgical applications because it is non-destructive, label-free, not impacted by water concentration, and can map an entire region of tissue. The objective of this paper is to demonstrate the meaningful spatial molecular information provided by Raman spectroscopy for identification of regions of normal brain, necrosis, diffusely infiltrating glioma and solid glioblastoma (GBM). Five frozen section tissues (1 normal, 1 necrotic, 1 GBM, and 2 infiltrating glioma) were mapped in their entirety using a 300-µm-square step size. Smaller regions of interest were also mapped using a 25-µm step size. The relative concentrations of relevant biomolecules were mapped across all tissues and compared with adjacent hematoxylin and eosin-stained sections, allowing identification of normal, GBM, and necrotic regions. Raman peaks and peak ratios mapped included 1003, 1313, 1431, 1585, and 1659 cm(-1). Tissue maps identified boundaries of grey and white matter, necrosis, GBM, and infiltrating tumor. Complementary information, including relative concentration of lipids, protein, nucleic acid, and hemoglobin, was presented in a manner which can be easily adapted for in vivo tissue mapping. Raman spectroscopy can successfully provide label-free imaging of tissue characteristics with high accuracy. It can be translated to a surgical or laboratory tool for rapid, non-destructive imaging of tumor margins.

  15. Ultrasensitive detection of phenolic antioxidants by surface enhanced Raman spectroscopy

    Science.gov (United States)

    Ornelas-Soto, N.; Aguilar-Hernández, I. A.; Afseth, N.; López-Luke, T.; Contreras-Torres, F. F.; Wold, J. P.

    2017-08-01

    Surface-Enhanced Raman Spectroscopy (SERS) is a powerful surface-sensitive technique to study the vibrational properties of analytes at very low concentrations. In this study, ferulic acid, p-coumaric acid, caffeic acid and sinapic acid were analyzed by SERS using Ag colloids. Analytes were detected up to 2.5x10-9M. For caffeic acid and coumaric acid, this detection limit has been reached for the first time, as well as the SERS analysis of sinapic acid using silver colloids.

  16. Theranostic Gold Nanoantennas for Simultaneous Multiplexed Raman Imaging of Immunomarkers and Photothermal Therapy.

    Science.gov (United States)

    Webb, Joseph A; Ou, Yu-Chuan; Faley, Shannon; Paul, Eden P; Hittinger, Joseph P; Cutright, Camden C; Lin, Eugene C; Bellan, Leon M; Bardhan, Rizia

    2017-07-31

    In this study, we demonstrate the theranostic capability of actively targeted, site-specific multibranched gold nanoantennas (MGNs) in triple-negative breast cancer (TNBC) cells in vitro. By utilizing multiplexed surface-enhanced Raman scattering (SERS) imaging, enabled by the narrow peak widths of Raman signatures, we simultaneously targeted immune checkpoint receptor programmed death ligand 1 (PDL1) and the epidermal growth factor receptor (EGFR) overexpressed in TNBC cells. A 1:1 mixture of MGNs functionalized with anti-PDL1 antibodies and Raman tag 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) and MGNs functionalized with anti-EGFR antibodies and Raman tag para -mercaptobenzoic acid ( p MBA) were incubated with the cells. SERS imaging revealed a cellular traffic map of MGN localization by surface binding and receptor-mediated endocytosis, enabling targeted diagnosis of both biomarkers. Furthermore, cells incubated with anti-EGFR- p MBA-MGNs and illuminated with an 808 nm laser for 15 min at 4.7 W/cm 2 exhibited photothermal cell death only within the laser spot (indicated by live/dead cell fluorescence assay). Therefore, this study not only provides an optical imaging platform that can track immunomarkers with spatiotemporal control but also demonstrates an externally controlled light-triggered therapeutic approach enabling receptor-specific treatment with biocompatible theranostic nanoprobes.

  17. Pulsed Raman fiber laser and multispectral imaging in three dimensions

    DEFF Research Database (Denmark)

    Andersen, Joachim F.; Busck, Jens; Heiselberg, Henning

    2006-01-01

    Raman scattering in single-mode optical fibers is exploited to generate multispectral light from a green nanolaser with high pulse repetition rate. Each pulse triggers a picosecond camera and measures the distance by time-of-flight in each of the 0.5 Mpixels. Three-dimensional images...... are then constructed with submillimeter accuracy for all visible colors. The generation of a series of Stokes peaks by Raman scattering in a Si fiber is discussed in detail and the laser radar technique is demonstrated. The data recording takes only a few seconds, and the high accuracy 3D color imaging works at ranges...... up to ∼200 m. Applications for optical tomography in highly scattering media such as water and human tissue are mentioned. © 2006 Optical Society of America....

  18. Single-Molecule Chemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Zrimsek, Alyssa B; Chiang, Naihao; Mattei, Michael; Zaleski, Stephanie; McAnally, Michael O; Chapman, Craig T; Henry, Anne-Isabelle; Schatz, George C; Van Duyne, Richard P

    2017-06-14

    Single-molecule (SM) surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) have emerged as analytical techniques for characterizing molecular systems in nanoscale environments. SERS and TERS use plasmonically enhanced Raman scattering to characterize the chemical information on single molecules. Additionally, TERS can image single molecules with subnanometer spatial resolution. In this review, we cover the development and history of SERS and TERS, including the concept of SERS hot spots and the plasmonic nanostructures necessary for SM detection, the past and current methodologies for verifying SMSERS, and investigations into understanding the signal heterogeneities observed with SMSERS. Moving on to TERS, we cover tip fabrication and the physical origins of the subnanometer spatial resolution. Then, we highlight recent advances of SMSERS and TERS in fields such as electrochemistry, catalysis, and SM electronics, which all benefit from the vibrational characterization of single molecules. SMSERS and TERS provide new insights on molecular behavior that would otherwise be obscured in an ensemble-averaged measurement.

  19. Aggregation of nanoparticles in endosomes and lysosomes produces surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Lucas, Leanne J.; Chen, Xiaoke K.; Smith, Aaron J.; Korbelik, Mladen; Zeng, Haishan; Lee, Patrick W. K.; Hewitt, Kevin Cecil

    2015-01-01

    The purpose of this study was to explore the use of surface-enhanced Raman spectroscopy (SERS) to image the distribution of epidermal growth factor receptor (EGFR) in cells. To accomplish this task, 30-nm gold nanoparticles (AuNPs) tagged with antibodies to EGFR (1012 per mL) were incubated with cells (106 per mL) of the A431 human epidermoid carcinoma and normal human bronchial epithelial cell lines. Using the 632.8-nm excitation line of a He-Ne laser, Raman spectroscopy measurements were performed using a point mapping scheme. Normal cells show little to no enhancement. SERS signals were observed inside the cytoplasm of A431 cells with an overall enhancement of 4 to 7 orders of magnitude. Raman intensity maps of the 1450 and 1583 cm-1 peaks correlate well with the expected distribution of EGFR and AuNPs, aggregated following uptake by endosomes and lysosomes. Spectral features from tyrosine and tryptophan residues dominate the SERS signals.

  20. Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.

    Science.gov (United States)

    McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C

    2016-09-07

    We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.

  1. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    International Nuclear Information System (INIS)

    Liu, Jun; Zhou, Ji; Tang, Bin; Zeng, Tian; Li, Yaling; Li, Jingliang; Ye, Yong; Wang, Xungai

    2016-01-01

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  2. Surface-enhanced raman optical data storage system

    Science.gov (United States)

    Vo-Dinh, Tuan

    1994-01-01

    An improved Surface-Enhanced Raman Optical Data Storage System (SERODS) is disclosed. In the improved system, entities capable of existing in multiple reversible states are present on the storage device. Such entities result in changed Surface-Enhanced Raman Scattering (SERS) when localized state changes are effected in less than all of the entities. Therefore, by changing the state of entities in localized regions of a storage device, the SERS emissions in such regions will be changed. When a write-on device is controlled by a data signal, such a localized regions of changed SERS emissions will correspond to the data written on the device. The data may be read by illuminating the surface of the storage device with electromagnetic radiation of an appropriate frequency and detecting the corresponding SERS emissions. Data may be deleted by reversing the state changes of entities in regions where the data was initially written. In application, entities may be individual molecules which allows for the writing of data at the molecular level. A read/write/delete head utilizing near-field quantum techniques can provide for a write/read/delete device capable of effecting state changes in individual molecules, thus providing for the effective storage of data at the molecular level.

  3. Trace drug analysis by surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Farquharson, Stuart; Lee, Vincent Y.

    2000-12-01

    Drug overdose involves more than 10 percent of emergency room (ER) cases, and a method to rapidly identify and quantify the abused drug is critical to the ability of the ER physician to administer the appropriate care. To this end, we have been developing a surface-enhanced Raman (SER) active material capable of detecting target drugs at physiological concentrations in urine. The SER-active material consists of a metal-doped sol-gel that provides not only a million fold increase in sensitivity but also reproducible measurements. The porous silica network offers a unique environment for stabilizing SER active metal particles and the high surface area increase the interaction between the analyte and metal particles. The sol-gel has been coated on the inside walls of glass samples vials, such that urine specimens may simply be introduced for analysis. Here we present the surface-enhanced Raman spectra of a series of barbiturates, actual urine specimens, and a drug 'spiked' urine specimen. The utility of pH adjustment to suppress dominant biochemicals associated with urine is also presented.

  4. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Zhou, Ji [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Tang, Bin, E-mail: bin.tang@deakin.edu.au [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Zeng, Tian; Li, Yaling [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Li, Jingliang [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Ye, Yong, E-mail: yeyong@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Wang, Xungai [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia)

    2016-11-15

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  5. Shape-dependent surface-enhanced Raman scattering in gold–Raman-probe–silica sandwiched nanoparticles for biocompatible applications

    International Nuclear Information System (INIS)

    Li Ming; Cushing, Scott K; Lankford, Jessica; Wu, Nianqiang; Zhang Jianming; Ma Dongling; Aguilar, Zoraida P

    2012-01-01

    To meet the requirement of Raman probes (labels) for biocompatible applications, a synthetic approach has been developed to sandwich the Raman-probe (malachite green isothiocyanate, MGITC) molecules between the gold core and the silica shell in gold–SiO 2 composite nanoparticles. The gold–MGITC–SiO 2 sandwiched structure not only prevents the Raman probe from leaking out but also improves the solubility of the nanoparticles in organic solvents and in aqueous solutions even with high ionic strength. To amplify the Raman signal, three types of core, gold nanospheres, nanorods and nanostars, have been chosen as the substrates of the Raman probe. The effect of the core shape on the surface-enhanced Raman scattering (SERS) has been investigated. The colloidal nanostars showed the highest SERS enhancement factor while the nanospheres possessed the lowest SERS activity under excitation with 532 and 785 nm lasers. Three-dimensional finite-difference time domain (FDTD) simulation showed significant differences in the local electromagnetic field distributions surrounding the nanospheres, nanorods, and nanostars, which were induced by the localized surface plasmon resonance (LSPR). The electromagnetic field was enhanced remarkably around the two ends of the nanorods and around the sharp tips of the nanostars. This local electromagnetic enhancement made the dominant contribution to the SERS enhancement. Both the experiments and the simulation revealed the order nanostars > nanorods > nanospheres in terms of the enhancement factor. Finally, the biological application of the nanostar–MGITC–SiO 2 nanoparticles has been demonstrated in the monitoring of DNA hybridization. In short, the gold–MGITC–SiO 2 sandwiched nanoparticles can be used as a Raman probe that features high sensitivity, good water solubility and stability, low-background fluorescence, and the absence of photobleaching for future biological applications. (paper)

  6. Stimulated Raman spectroscopy and nanoscopy of molecules using near field photon induced forces without resonant electronic enhancement gain

    Energy Technology Data Exchange (ETDEWEB)

    Tamma, Venkata Ananth [CaSTL Center, Department of Chemistry, University of California, Irvine, California 92697 (United States); Huang, Fei; Kumar Wickramasinghe, H., E-mail: hkwick@uci.edu [Department of Electrical Engineering and Computer Science, 142 Engineering Tower, University of California, Irvine, California 92697 (United States); Nowak, Derek [Molecular Vista, Inc., 6840 Via Del Oro, San Jose, California 95119 (United States)

    2016-06-06

    We report on stimulated Raman spectroscopy and nanoscopy of molecules, excited without resonant electronic enhancement gain, and recorded using near field photon induced forces. Photon-induced interaction forces between the sharp metal coated silicon tip of an Atomic Force Microscope (AFM) and a sample resulting from stimulated Raman excitation were detected. We controlled the tip to sample spacing using the higher order flexural eigenmodes of the AFM cantilever, enabling the tip to come very close to the sample. As a result, the detection sensitivity was increased compared with previous work on Raman force microscopy. Raman vibrational spectra of azobenzene thiol and l-phenylalanine were measured and found to agree well with published results. Near-field force detection eliminates the need for far-field optical spectrometer detection. Recorded images show spatial resolution far below the optical diffraction limit. Further optimization and use of ultrafast pulsed lasers could push the detection sensitivity towards the single molecule limit.

  7. Surface-Enhanced Raman Spectroscopy Study of 4-ATP on Gold Nanoparticles for Basal Cell Carcinoma Fingerprint Detection

    Science.gov (United States)

    Quynh, Luu Manh; Nam, Nguyen Hoang; Kong, K.; Nhung, Nguyen Thi; Notingher, I.; Henini, M.; Luong, Nguyen Hoang

    2016-05-01

    The surface-enhanced Raman signals of 4-aminothiophenol (4-ATP) attached to the surface of colloidal gold nanoparticles with size distribution of 2 to 5 nm were used as a labeling agent to detect basal cell carcinoma (BCC) of the skin. The enhanced Raman band at 1075 cm-1 corresponding to the C-S stretching vibration in 4-ATP was observed during attachment to the surface of the gold nanoparticles. The frequency and intensity of this band did not change when the colloids were conjugated with BerEP4 antibody, which specifically binds to BCC. We show the feasibility of imaging BCC by surface-enhanced Raman spectroscopy, scanning the 1075 cm-1 band to detect the distribution of 4-ATP-coated gold nanoparticles attached to skin tissue ex vivo.

  8. Horizontal silicon nanowires for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Gebavi, Hrvoje; Ristić, Davor; Baran, Nikola; Mikac, Lara; Mohaček-Grošev, Vlasta; Gotić, Marijan; Šikić, Mile; Ivanda, Mile

    2018-01-01

    The main purpose of this paper is to focus on details of the fabrication process of horizontally and vertically oriented silicon nanowires (SiNWs) substrates for the application of surface-enhanced Raman spectroscopy (SERS). The fabrication process is based on the vapor-liquid-solid method and electroless-assisted chemical etching, which, as the major benefit, resulting in the development of economical, easy-to-prepare SERS substrates. Furthermore, we examined the fabrication of Au coated Ag nanoparticles (NPs) on the SiNWs substrates in such a way as to diminish the influence of silver NPs corrosion, which, in turn, enhanced the SERS time stability, thus allowing for wider commercial applications. The substances on which high SERS sensitivity was proved are rhodamine (R6G) and 4-mercaptobenzoic acid (MBA), with the detection limits of 10-8 M and 10-6 M, respectively.

  9. The high throughput virtual slit enables compact, inexpensive Raman spectral imagers

    Science.gov (United States)

    Gooding, Edward; Deutsch, Erik R.; Huehnerhoff, Joseph; Hajian, Arsen R.

    2018-02-01

    Raman spectral imaging is increasingly becoming the tool of choice for field-based applications such as threat, narcotics and hazmat detection; air, soil and water quality monitoring; and material ID. Conventional fiber-coupled point source Raman spectrometers effectively interrogate a small sample area and identify bulk samples via spectral library matching. However, these devices are very slow at mapping over macroscopic areas. In addition, the spatial averaging performed by instruments that collect binned spectra, particularly when used in combination with orbital raster scanning, tends to dilute the spectra of trace particles in a mixture. Our design, employing free space line illumination combined with area imaging, reveals both the spectral and spatial content of heterogeneous mixtures. This approach is well suited to applications such as detecting explosives and narcotics trace particle detection in fingerprints. The patented High Throughput Virtual Slit1 is an innovative optical design that enables compact, inexpensive handheld Raman spectral imagers. HTVS-based instruments achieve significantly higher spectral resolution than can be obtained with conventional designs of the same size. Alternatively, they can be used to build instruments with comparable resolution to large spectrometers, but substantially smaller size, weight and unit cost, all while maintaining high sensitivity. When used in combination with laser line imaging, this design eliminates sample photobleaching and unwanted photochemistry while greatly enhancing mapping speed, all with high selectivity and sensitivity. We will present spectral image data and discuss applications that are made possible by low cost HTVS-enabled instruments.

  10. Cavity-Type DNA Origami-Based Plasmonic Nanostructures for Raman Enhancement.

    Science.gov (United States)

    Zhao, Mengzhen; Wang, Xu; Ren, Shaokang; Xing, Yikang; Wang, Jun; Teng, Nan; Zhao, Dongxia; Liu, Wei; Zhu, Dan; Su, Shao; Shi, Jiye; Song, Shiping; Wang, Lihua; Chao, Jie; Wang, Lianhui

    2017-07-05

    DNA origami has been established as addressable templates for site-specific anchoring of gold nanoparticles (AuNPs). Given that AuNPs are assembled by charged DNA oligonucleotides, it is important to reduce the charge repulsion between AuNPs-DNA and the template to realize high yields. Herein, we developed a cavity-type DNA origami as templates to organize 30 nm AuNPs, which formed dimer and tetramer plasmonic nanostructures. Transmission electron microscopy images showed that high yields of dimer and tetramer plasmonic nanostructures were obtained by using the cavity-type DNA origami as the template. More importantly, we observed significant Raman signal enhancement from molecules covalently attached to the plasmonic nanostructures, which provides a new way to high-sensitivity Raman sensing.

  11. Modulated Raman Spectroscopy for Enhanced Cancer Diagnosis at the Cellular Level

    Science.gov (United States)

    De Luca, Anna Chiara; Dholakia, Kishan; Mazilu, Michael

    2015-01-01

    Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine clinical care. The review summarizes the state-of-the-art methods to remove the fluorescence background and explores recent achievements to address this issue obtained with modulated Raman spectroscopy. This innovative approach can be used to extract the Raman spectral component from the fluorescence background and improve the quality of the Raman signal. We describe the potential of modulated Raman spectroscopy as a rapid, inexpensive and accurate clinical tool to detect the presence of bladder cancer cells. Finally, in a broader context, we show how this approach can greatly enhance the sensitivity of integrated Raman spectroscopy and microfluidic systems, opening new prospects for portable higher throughput Raman cell sorting. PMID:26110401

  12. Enhancement of blurred image portions

    NARCIS (Netherlands)

    2008-01-01

    This invention relates to a method for image enhancement, comprising a first step ( 41 ) of distinguishing blurred and non-blurred image portions of an input image, and a second step ( 42 ) of enhancing at least one of said blurred image portions of said input image to produce an output image. Said

  13. Indium nanoparticles for ultraviolet surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Das, Rupali; Soni, R. K.

    2018-05-01

    Ultraviolet Surface-enhanced Raman spectroscopy (UVSERS) has emerged as an efficient molecular spectroscopy technique for ultra-sensitive and ultra-low detection of analyte concentration. The generic SERS substrates based on gold and silver nanostructures have been extensively explored for high local electric field enhancement only in visible-NIR region of the electromagnetic spectrum. The template synthesis of controlled nanoscale size metallic nanostructures supporting localized surface plasmon resonance (LSPR) in the UV region have been recently explored due to their ease of synthesis and potential applications in optoelectronic, catalysis and magnetism. Indium (In0) nanoparticles exhibit active surface plasmon resonance (SPR) in ultraviolet (UV) and deep-ultaviolet (DUV) region with optimal absorption losses. This extended accessibility makes indium a promising material for UV plasmonic, chemical sensing and more recently in UV-SERS. In this work, spherical indium nanoparticles (In NPs) were synthesized by modified polyol reduction method using NaBH4 having local surface plasmon resonance near 280 nm. The as-synthesized spherical In0 nanoparticles were then coated with thin silica shells of thickness ˜ 5nm by a modified Stober method protecting the nanoparticles from agglomeration, direct contact with the probed molecules as well as prevent oxidation of the nanoparticles. Morphological evolution of In0 nanoparticles and SiO2 coating were characterized by transmission electron microscope (TEM). An enhanced near resonant shell-isolated SERS activity from thin film of tryptophan (Tryp) molecules deposited on indium coated substrates under 325nm UV excitation was observed. Finite difference time domain (FDTD) method is employed to comprehend the experimental results and simulate the electric field contours which showed amplified electromagnetic field localized around the nanostructures. The comprehensive analysis indicates that indium is a promising alternate

  14. Thermally generated metals for plasmonic coloring and surface-enhanced Raman sensing

    Science.gov (United States)

    Huang, Zhenping; Chen, Jian; Liu, Guiqiang; Wang, Yan; Liu, Yi; Tang, Li; Liu, Zhengqi

    2018-03-01

    Spectral coloring glass and its application on the surface-enhanced Raman scattering are demonstrated experimentally via a simple and moderate heat-treating of the top ultrathin gold film to create discrete nanoparticles, which can produce localized surface plasmon resonances and strong plasmonic near-field coupling effects. Ultrathin metal films with a wide range of thicknesses are investigated by different heat-treatment processes. The annealed metal films have been demonstrated with a series of spectral coloring responses. Moreover, the microscopy images of the metal film structures confirm the formation of distinct geometry features in these operation procedures. Densely packed nanoparticles are observed for the ultrathin metal film with the single-digit level of thickness. With increasing the film thickness over 10 nm, metallic clusters and porous morphologies can be obtained. Importantly, the metallic resonators can provide enhanced Raman scattering with the detection limit down to 10 - 7 molL - 1 of Rhodamine 6G molecules due to the excitation of plasmon resonances and strong near-field coupling effects. These features hold great potential for large-scale and low-cost production of colored glass and Raman substrate.

  15. Assessing Telomere Length Using Surface Enhanced Raman Scattering

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Cui, Yiping

    2014-11-01

    Telomere length can provide valuable insight into telomeres and telomerase related diseases, including cancer. Here, we present a brand-new optical telomere length measurement protocol using surface enhanced Raman scattering (SERS). In this protocol, two single strand DNA are used as SERS probes. They are labeled with two different Raman molecules and can specifically hybridize with telomeres and centromere, respectively. First, genome DNA is extracted from cells. Then the telomere and centromere SERS probes are added into the genome DNA. After hybridization with genome DNA, excess SERS probes are removed by magnetic capturing nanoparticles. Finally, the genome DNA with SERS probes attached is dropped onto a SERS substrate and subjected to SERS measurement. Longer telomeres result in more attached telomere probes, thus a stronger SERS signal. Consequently, SERS signal can be used as an indicator of telomere length. Centromere is used as the inner control. By calibrating the SERS intensity of telomere probe with that of the centromere probe, SERS based telomere measurement is realized. This protocol does not require polymerase chain reaction (PCR) or electrophoresis procedures, which greatly simplifies the detection process. We anticipate that this easy-operation and cost-effective protocol is a fine alternative for the assessment of telomere length.

  16. Chip-Scale Bioassays Based on Surface-Enhanced Raman Scattering: Fundamentals and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hye-Young [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    This work explores the development and application of chip-scale bioassays based on surface-enhanced Raman scattering (SERS) for high throughput and high sensitivity analysis of biomolecules. The size effect of gold nanoparticles on the intensity of SERS is first presented. A sandwich immunoassay was performed using Raman-labeled immunogold nanoparticles with various sizes. The SERS responses were correlated to particle densities, which were obtained by atomic force microscopy (AFM). The response of individual particles was also investigated using Raman-microscope and an array of gold islands on a silicon substrate. The location and the size of individual particles were mapped using AFM. The next study describes a low-level detection of Escherichia coli 0157:H7 and simulants of biological warfare agents in a sandwich immunoassay format using SERS labels, which have been termed Extrinsic Raman labels (ERLs). A new ERL scheme based on a mixed monolayer is also introduced. The mixed monolayer ERLs were created by covering the gold nanoparticles with a mixture of two thiolates, one thiolate for covalently binding antibody to the particle and the other thiolate for producing a strong Raman signal. An assay platform based on mixed self-assembled monolayers (SAMs) on gold is then presented. The mixed SAMs were prepared from dithiobis(succinimidyl undecanoate) (DSU) to covalently bind antibodies on gold substrate and oligo(ethylene glycol)-terminated thiol to prevent nonspecific adsorption of antibodies. After the mixed SAMs surfaces, formed from various mole fraction of DSU were incubated with antibodies, AFM was used to image individual antibodies on the surface. The final study presents a collaborative work on the single molecule adsorption of YOYO-I labeled {lambda}-DNA at compositionally patterned SAMs using total internal reflection fluorescence microscopy. The role of solution pH, {lambda}-DNA concentration, and domain size was investigated. This work also revealed

  17. Greatly enhanced Raman scattering and upconversion luminescence of Au–NaYF{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Tao [State Key Laboratory on Integrated Optoelectronics,College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211 (China); Li, Junpeng [Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211 (China); Qin, Weiping, E-mail: wpqin@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics,College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Zhou, Jun, E-mail: zhoujun@nbu.edu.cn [Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211 (China)

    2014-12-15

    Novel dual function Au–NaYF{sub 4} nanocomposites were prepared by a facile wet chemical method. Hexagonal NaYF{sub 4} nanocrystals (NCs) were first produced by a hydrothermal method. Then, these NaYF{sub 4} NCs were decorated with gold nanoparticles (NPs) to form hybrid nanostructures. In this dual mode probe, surface enhanced Raman scattering (SERS) and field enhanced fluorescence can be generated independently by using different excitation wavelengths. It was found that the attached gold NPs on the rough surfaces of NaYF{sub 4} NCs might generate high density localized electric fields, which could lead to both efficient Raman scattering signal and upconversion (UC) luminescence. The enhancement factors of SERS signals from Au–NaYF{sub 4} nanocomposites were investigated using 4-mercaptobenzoic acid. The mechanism of enhanced UC luminescence from the nanocomposites was also discussed based on the population and photoluminescence processes of doped trivalent lanthanide ions. These dual mode nanocomposites may find potential applications in biological detection, imaging, and sensing. - Highlights: • Novel dual function Au–NaYF{sub 4} nanocomposites were successfully fulfilled by a facial wet chemical method. • Field enhanced fluorescence and SERS can be generated independently by using different excitation wavelengths. • The EF value of this Au–NaYF{sub 4} substrate was as high as 8.17×10{sup 7}. • The largest ER of UC emissions from Gd{sup 3+} ion in Au–NaYF{sub 4} nanocomposites appeared to be 76.

  18. Angiogenesis - a crucial step in breast cancer growth, progression and dissemination by Raman imaging

    Science.gov (United States)

    Kopeć, Monika; Abramczyk, Halina

    2018-06-01

    Combined micro-Raman imaging and AFM imaging are efficient methods for analyzing human tissue due to their high spatial and spectral resolution as well as sensitivity to subtle chemical, structural and topographical changes. The aim of this study was to determine biochemical composition and mechanical topography around blood vessels in the tumor mass of human breast tissue. Significant alterations of the chemical composition and structural architecture around the blood vessel were found compared to the normal breast tissue. A pronounced increase of collagen-fibroblast-glycocalyx network, as well as enhanced lactic acid, and glycogen activity in patients affected by breast cancer were reported.

  19. Surface-enhanced Raman fiberoptic sensors for remote monitoring

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  20. Surface-enhanced Raman scattering in art and archaeology

    Science.gov (United States)

    Leona, Marco

    2005-11-01

    The identification of natural dyes found in archaeological objects and in works of art as textile dyes and lake pigments is a demanding analytical task. To address the problems raised by the very low dye content of dyed fibers and lake pigments, and by the requirement to remove only microscopic samples, surface enhanced Raman scattering techniques were investigated for application to museum objects. SERS gives excellent results with the majority of natural dyes, including: alizarin, purpurin, laccaic acid, carminic acid, kermesic acid, shikonin, juglone, lawsone, brazilin and brazilein, haematoxylin and haematein, fisetin, quercitrin, quercetin, rutin, and morin. In this study, limits of detection were determined for representative dyes and different SERS supports such as citrate reduced Ag colloid and silver nanoisland films. SERS was successfully used to identify natural madder in a microscopic fragment from a severely degraded 11th Century Byzantine textile recently excavated in Amorium, Turkey.

  1. Biomedical Applications of Micro-Raman and Surface-Enhanced Raman Scattering (SERS) Technology

    Science.gov (United States)

    2012-10-01

    hydroxyapatite ; 1073cm-1, carbonate from carbonate apatite; 1442cm-1, cholesterol and cholesterol esters. 17 Table 1. Tentative assignment and Raman peak...allowed for the discrete location of atherosclerotic plaques. Raman peaks at 961 and 1073 cm-1 reveal the presence of calcium hydroxyapatite and... hydroxyapatite are located within the vessel wall. Similarly, Fig. 5 maps the Raman intensity of the peak at 1073cm-1, which is indicative of

  2. Aggregation of gold nanoparticles followed by methotrexate release enables Raman imaging of drug delivery into cancer cells

    International Nuclear Information System (INIS)

    Durgadas, C. V.; Sharma, C. P.; Paul, W.; Rekha, M. R.; Sreenivasan, K.

    2012-01-01

    This study refers an aqueous synthesis of methotrexate (MTX)-conjugated gold nanoparticles (GNPs), their interaction with HepG2 cells, and the use of Raman imaging to observe cellular internalization and drug delivery. GNPs of average size 3.5–5 nm were stabilized using the amine terminated bifunctional biocompatible copolymer and amended by conjugating MTX, an anticancer drug. The nanoparticles were released MTX at a faster rate in acidic pH and subsequently found to form aggregates. The Raman signals of cellular components were found to be enhanced by the aggregated particles enabling the mapping to visualize site-specific drug delivery. The methodology seems to have potential in optimizing the characteristics of nanodrug carriers for emptying the cargo precisely at specified sites.Graphical AbstractDrug release induced particle aggregation enhances Raman signals to aid in imaging.

  3. Raman imaging from microscopy to macroscopy: Quality and safety control of biological materials

    Science.gov (United States)

    Raman imaging can analyze biological materials by generating detailed chemical images. Over the last decade, tremendous advancements in Raman imaging and data analysis techniques have overcome problems such as long data acquisition and analysis times and poor sensitivity. This review article introdu...

  4. Live-cell stimulated Raman scattering imaging of alkyne-tagged biomolecules.

    Science.gov (United States)

    Hong, Senlian; Chen, Tao; Zhu, Yuntao; Li, Ang; Huang, Yanyi; Chen, Xing

    2014-06-02

    Alkynes can be metabolically incorporated into biomolecules including nucleic acids, proteins, lipids, and glycans. In addition to the clickable chemical reactivity, alkynes possess a unique Raman scattering within the Raman-silent region of a cell. Coupling this spectroscopic signature with Raman microscopy yields a new imaging modality beyond fluorescence and label-free microscopies. The bioorthogonal Raman imaging of various biomolecules tagged with an alkyne by a state-of-the-art Raman imaging technique, stimulated Raman scattering (SRS) microscopy, is reported. This imaging method affords non-invasiveness, high sensitivity, and molecular specificity and therefore should find broad applications in live-cell imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Bare and protected sputtered-noble-metal films for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Talaga, David; Bonhommeau, Sébastien

    2014-11-01

    Sputtered silver and gold films with different surface morphologies have been prepared and coated with a benzenethiol self-assembled monolayer. Rough noble metal films showed strong Raman features assigned to adsorbed benzenethiol molecules upon irradiation over a wide energy range in the visible spectrum, which disclosed the occurrence of a significant surface-enhanced Raman scattering with maximal enhancement factors as high as 6 × 106. In addition, the adsorption of ethanethiol onto silver surfaces hinders their corrosion over days while preserving mostly intact enhancement properties of naked silver. This study may be applied to develop stable and efficient metalized probes for tip-enhanced Raman spectroscopy.

  6. Surface-enhanced Raman spectroscopy based on conical holed enhancing substrates

    International Nuclear Information System (INIS)

    Chen, Yao; Chen, Zeng-Ping; Zuo, Qi; Shi, Cai-Xia; Yu, Ru-Qin

    2015-01-01

    In this contribution, surface-enhanced Raman spectroscopy (SERS) based on conical holed glass substrates deposited with silver colloids was reported for the first time. It combines the advantages of both dry SERS assays based on plane films deposited with silver colloids and wet SERS assays utilizing cuvettes or capillary tubes. Compared with plane glass substrates deposited with silver colloids, the conical holed glass substrates deposited with silver colloids exhibited five-to ten-folds of increase in the rate of signal enhancement, due to the internal multiple reflections of both the excitation laser beam and the Raman scattering photons within conical holes. The application of conical holed glass substrates could also yield significantly stronger and more reproducible SERS signals than SERS assays utilizing capillary tubes to sample the mixture of silver colloids and the solution of the analyte of interest. The conical holed glass substrates in combination with the multiplicative effects model for surface-enhanced Raman spectroscopy (MEM SERS ) achieved quite sensitive and precise quantification of 6-mercaptopurine in complex plasma samples with an average relative prediction error of about 4% and a limit of detection of about 0.02 μM using a portable i-Raman 785H spectrometer. It is reasonable to expect that SERS technique based on conical holed enhancing substrates in combination with MEM SERS model can be developed and extended to other application areas such as drug detection, environmental monitoring, and clinic analysis, etc. - Highlights: • A novel conical holed SERS enhancing substrate was designed and manufactured. • The optimal conical holed glass substrates can produce stronger SERS signal. • The novel substrates can overcome the shortcomings of both dry and wet methods. • The novel substrates coupled with MEM SERS can realize quantitative SERS assays

  7. Unraveling the Raman Enhancement Mechanism on 1T'-Phase ReS2 Nanosheets.

    Science.gov (United States)

    Miao, Peng; Qin, Jing-Kai; Shen, Yunfeng; Su, Huimin; Dai, Junfeng; Song, Bo; Du, Yunchen; Sun, Mengtao; Zhang, Wei; Wang, Hsing-Lin; Xu, Cheng-Yan; Xu, Ping

    2018-04-01

    2D transition metal dichalcogenides materials are explored as potential surface-enhanced Raman spectroscopy substrates. Herein, a systematic study of the Raman enhancement mechanism on distorted 1T (1T') rhenium disulfide (ReS 2 ) nanosheets is demonstrated. Combined Raman and photoluminescence studies with the introduction of an Al 2 O 3 dielectric layer unambiguously reveal that Raman enhancement on ReS 2 materials is from a charge transfer process rather than from an energy transfer process, and Raman enhancement is inversely proportional while the photoluminescence quenching effect is proportional to the layer number (thickness) of ReS 2 nanosheets. On monolayer ReS 2 film, a strong resonance-enhanced Raman scattering effect dependent on the laser excitation energy is detected, and a detection limit as low as 10 -9 m can be reached from the studied dye molecules such as rhodamine 6G and methylene blue. Such a high enhancement factor achieved through enhanced charge interaction between target molecule and substrate suggests that with careful consideration of the layer-number-dependent feature and excitation-energy-related resonance effect, ReS 2 is a promising Raman enhancement platform for sensing applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Multiple layered metallic nanostructures for strong surface-enhanced Raman spectroscopy enhancement

    International Nuclear Information System (INIS)

    Xia, Ming; Xie, Ya-Hong; Qiao Kuan; Cheng Zhiyuan

    2016-01-01

    We report a systematic study on a practical way of patterning metallic nanostructures to achieve high surface-enhanced Raman spectroscopy (SERS) enhancement factors (EFs) and high hot-spot density. By simply superimposing a 1-layer Au nanotriangle array on another to form a multilayer nanotriangle array, the SERS signal can be enhanced by 2 orders of magnitude compared with a 1-layer nanotriangle array. The drastic increases in the SERS EF and the hot spot density of the multilayer Au nanotriangle array are due to the increase in the number of gaps formed between Au nanotriangles and the decrease of the gap width. (author)

  9. Novel medical image enhancement algorithms

    Science.gov (United States)

    Agaian, Sos; McClendon, Stephen A.

    2010-01-01

    In this paper, we present two novel medical image enhancement algorithms. The first, a global image enhancement algorithm, utilizes an alpha-trimmed mean filter as its backbone to sharpen images. The second algorithm uses a cascaded unsharp masking technique to separate the high frequency components of an image in order for them to be enhanced using a modified adaptive contrast enhancement algorithm. Experimental results from enhancing electron microscopy, radiological, CT scan and MRI scan images, using the MATLAB environment, are then compared to the original images as well as other enhancement methods, such as histogram equalization and two forms of adaptive contrast enhancement. An image processing scheme for electron microscopy images of Purkinje cells will also be implemented and utilized as a comparison tool to evaluate the performance of our algorithm.

  10. Surface-enhanced Raman scattering sensing on black silicon

    International Nuclear Information System (INIS)

    Gervinskas, Gediminas; Seniutinas, Gediminas; Hartley, Jennifer S.; Stoddart, Paul R.; Juodkazis, Saulius; Kandasamy, Sasikaran; Fahim, Narges F.

    2013-01-01

    Reactive ion etching was used to fabricate black-Si over the entire surface area of 4-inch Si wafers. After 20 min of the plasma treatment, surface reflection well below 2% was achieved over the 300-1000 nm spectral range. The spikes of the black-Si substrates were coated by gold, resulting in an island film for surface-enhanced Raman scattering (SERS) sensing. A detection limit of 1 x 10 -6 M (at count rate > 10 2 s -1 . mW -1 ) was achieved for rhodamine 6G in aqueous solution when drop cast onto a ∝ 100-nm-thick Au coating. The sensitivity increases for thicker coatings. A mixed mobile-on-immobile platform for SERS sensing is introduced by using dog-bone Au nanoparticles on the Au/black-Si substrate. The SERS intensity shows a non-linear dependence on the solid angle (numerical aperture of excitation/collection optics) for a thick gold coating that exhibits a 10 times higher enhancement. This shows promise for augmented sensitivity in SERS applications. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Surface-enhanced Raman scattering sensing on black silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gervinskas, Gediminas; Seniutinas, Gediminas; Hartley, Jennifer S.; Stoddart, Paul R.; Juodkazis, Saulius [Centre for Micro-Photonics and Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC (Australia); The Australian National Fabrication Facility-ANFF, Victoria node, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC (Australia); Kandasamy, Sasikaran [Melbourne Centre for Nanofabrication, Clayton, VIC (Australia); Fahim, Narges F. [Centre for Micro-Photonics and Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC (Australia)

    2013-12-15

    Reactive ion etching was used to fabricate black-Si over the entire surface area of 4-inch Si wafers. After 20 min of the plasma treatment, surface reflection well below 2% was achieved over the 300-1000 nm spectral range. The spikes of the black-Si substrates were coated by gold, resulting in an island film for surface-enhanced Raman scattering (SERS) sensing. A detection limit of 1 x 10{sup -6} M (at count rate > 10{sup 2} s{sup -1}. mW{sup -1}) was achieved for rhodamine 6G in aqueous solution when drop cast onto a {proportional_to} 100-nm-thick Au coating. The sensitivity increases for thicker coatings. A mixed mobile-on-immobile platform for SERS sensing is introduced by using dog-bone Au nanoparticles on the Au/black-Si substrate. The SERS intensity shows a non-linear dependence on the solid angle (numerical aperture of excitation/collection optics) for a thick gold coating that exhibits a 10 times higher enhancement. This shows promise for augmented sensitivity in SERS applications. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Surface-Enhanced Raman Spectroscopy Based Quantitative Bioassay on Aptamer-Functionalized Nanopillars Using Large-Area Raman Mapping

    DEFF Research Database (Denmark)

    Yang, Jaeyoung; Palla, Mirko; Bosco, Filippo

    2013-01-01

    Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based biosensing approach for quantitative detection of biomolecules. A SERS substrate bearing gold-decorated silicon nanopillars......-to-spot variation in conventional SERS quantification. Furthermore, we have developed an analytical model capable of predicting experimental intensity distributions on the substrates for reliable quantification of biomolecules. Lastly, we have calculated the minimum needed area of Raman mapping for efficient...

  13. Quantitative volumetric Raman imaging of three dimensional cell cultures

    KAUST Repository

    Kallepitis, Charalambos

    2017-03-22

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell–material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.

  14. Quantitative volumetric Raman imaging of three dimensional cell cultures

    Science.gov (United States)

    Kallepitis, Charalambos; Bergholt, Mads S.; Mazo, Manuel M.; Leonardo, Vincent; Skaalure, Stacey C.; Maynard, Stephanie A.; Stevens, Molly M.

    2017-03-01

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell-material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.

  15. High-speed Vibrational Imaging and Spectral Analysis of Lipid Bodies by Compound Raman Microscopy

    OpenAIRE

    Slipchenko, Mikhail N.; Le, Thuc T.; Chen, Hongtao; Cheng, Ji-Xin

    2009-01-01

    Cells store excess energy in the form of cytoplasmic lipid droplets. At present, it is unclear how different types of fatty acids contribute to the formation of lipid-droplets. We describe a compound Raman microscope capable of both high-speed chemical imaging and quantitative spectral analysis on the same platform. We use a picosecond laser source to perform coherent Raman scattering imaging of a biological sample and confocal Raman spectral analysis at points of interest. The potential of t...

  16. Noise Suppression and Enhanced Focusability in Plasma Raman Amplifier with Multi-frequency Pump

    International Nuclear Information System (INIS)

    Balakin, A.A.; Fraiman, G.M.; Fisch, N.J.; Malkin, V.M.

    2003-01-01

    Laser pulse compression/amplification through Raman backscattering in plasmas can be facilitated by using multi-frequency pump laser beams. The efficiency of amplification is increased by suppressing the Raman instability of thermal fluctuations and seed precursors. Also the focusability of the amplified radiation is enhanced due to the suppression of large-scale longitudinal speckles in the pump wave structure

  17. Surface enhanced Raman spectroscopy: A review of recent applications in forensic science

    Science.gov (United States)

    Fikiet, Marisia A.; Khandasammy, Shelby R.; Mistek, Ewelina; Ahmed, Yasmine; Halámková, Lenka; Bueno, Justin; Lednev, Igor K.

    2018-05-01

    Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics.

  18. A SIGNAL ENHANCED PORTABLE RAMAN PROBE FOR ANESTHETIC GAS MONITORING

    Directory of Open Access Journals (Sweden)

    S. Schlüter

    2015-03-01

    Full Text Available The spontaneous Raman scattering technique is an excellent tool for a quantitative analysis of multi-species gas mixtures. It is a noninvasive optical method for species identification and gas phase concentration measurement of all Raman active molecules, since the intensity of the species specific Raman signal is linearly dependent on the concentration. Applying a continuous wave (CW laser it typically takes a few seconds to capture a gas phase Raman spectrum at room temperature. Nevertheless in contrast to these advantages the weak Raman signal intensity is a major drawback. Thus, it is still challenging to detect gas phase Raman spectra in alow-pressure regime with a temporal resolution of only a few 100 ms. In this work a fully functional gas phase Raman system for measurements in the low-pressure regime (p ≥ 980 hPa (absolute is presented. It overcomes the drawback of a weak Raman signal by using a multipass cavity. A description of the sensor setup and of the multipass arrangement will be presented. Moreover the complete functionality of the sensor system will be demonstrated by measurements at an anesthesia simulator under clinical relevant conditions and in comparison to a conventional gas monitor.

  19. Surface-Enhanced Raman Spectroscopy for Heterogeneous Catalysis Research

    NARCIS (Netherlands)

    Harvey, C.E.

    2013-01-01

    Raman spectroscopy is valuable characterization technique for the chemical analysis of heterogeneous catalysts, both under ex-situ and in-situ conditions. The potential for Raman to shine light on the chemical bonds present in a sample makes the method highly desirable for detailed catalyst

  20. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers

    DEFF Research Database (Denmark)

    Perozziello, Gerardo; Candeloro, Patrizio; De Grazia, Antonio

    2016-01-01

    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels-where the cells can flow one-by-one -, allowing single...... cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm...

  1. Wavelength modulated surface enhanced (resonance) Raman scattering for background-free detection.

    Science.gov (United States)

    Praveen, Bavishna B; Steuwe, Christian; Mazilu, Michael; Dholakia, Kishan; Mahajan, Sumeet

    2013-05-21

    Spectra in surface-enhanced Raman scattering (SERS) are always accompanied by a continuum emission called the 'background' which complicates analysis and is especially problematic for quantification and automation. Here, we implement a wavelength modulation technique to eliminate the background in SERS and its resonant version, surface-enhanced resonance Raman scattering (SERRS). This is demonstrated on various nanostructured substrates used for SER(R)S. An enhancement in the signal to noise ratio for the Raman bands of the probe molecules is also observed. This technique helps to improve the analytical ability of SERS by alleviating the problem due to the accompanying background and thus making observations substrate independent.

  2. Using Raman spectroscopic imaging for non-destructive analysis of filler distribution in chalk filled polypropylene

    DEFF Research Database (Denmark)

    Boros, Evelin; Porse, Peter Bak; Nielsen, Inga

    2016-01-01

    A feasibility study on using Raman spectral imaging for visualization and analysis of filler distribution in chalk filled poly-propylene samples has been carried out. The spectral images were acquired using a Raman spectrometer with 785 nm light source.Eight injection-molded samples with concentr...

  3. Tip-Enhanced Raman Voltammetry: Coverage Dependence and Quantitative Modeling.

    Science.gov (United States)

    Mattei, Michael; Kang, Gyeongwon; Goubert, Guillaume; Chulhai, Dhabih V; Schatz, George C; Jensen, Lasse; Van Duyne, Richard P

    2017-01-11

    Electrochemical atomic force microscopy tip-enhanced Raman spectroscopy (EC-AFM-TERS) was employed for the first time to observe nanoscale spatial variations in the formal potential, E 0' , of a surface-bound redox couple. TERS cyclic voltammograms (TERS CVs) of single Nile Blue (NB) molecules were acquired at different locations spaced 5-10 nm apart on an indium tin oxide (ITO) electrode. Analysis of TERS CVs at different coverages was used to verify the observation of single-molecule electrochemistry. The resulting TERS CVs were fit to the Laviron model for surface-bound electroactive species to quantitatively extract the formal potential E 0' at each spatial location. Histograms of single-molecule E 0' at each coverage indicate that the electrochemical behavior of the cationic oxidized species is less sensitive to local environment than the neutral reduced species. This information is not accessible using purely electrochemical methods or ensemble spectroelectrochemical measurements. We anticipate that quantitative modeling and measurement of site-specific electrochemistry with EC-AFM-TERS will have a profound impact on our understanding of the role of nanoscale electrode heterogeneity in applications such as electrocatalysis, biological electron transfer, and energy production and storage.

  4. Electromagnetic theories of surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin

    2017-07-07

    Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

  5. COMPARISON OF IMAGE ENHANCEMENT METHODS FOR CHROMOSOME KARYOTYPE IMAGE ENHANCEMENT

    Directory of Open Access Journals (Sweden)

    Dewa Made Sri Arsa

    2017-02-01

    Full Text Available The chromosome is a set of DNA structure that carry information about our life. The information can be obtained through Karyotyping. The process requires a clear image so the chromosome can be evaluate well. Preprocessing have to be done on chromosome images that is image enhancement. The process starts with image background removing. The image will be cleaned background color. The next step is image enhancement. This paper compares several methods for image enhancement. We evaluate some method in image enhancement like Histogram Equalization (HE, Contrast-limiting Adaptive Histogram Equalization (CLAHE, Histogram Equalization with 3D Block Matching (HE+BM3D, and basic image enhancement, unsharp masking. We examine and discuss the best method for enhancing chromosome image. Therefore, to evaluate the methods, the original image was manipulated by the addition of some noise and blur. Peak Signal-to-noise Ratio (PSNR and Structural Similarity Index (SSIM are used to examine method performance. The output of enhancement method will be compared with result of Professional software for karyotyping analysis named Ikaros MetasystemT M . Based on experimental results, HE+BM3D method gets a stable result on both scenario noised and blur image.

  6. Quantum mechanical limit to plasmonic enhancement as observed by surface-enhanced Raman scattering.

    Science.gov (United States)

    Zhu, Wenqi; Crozier, Kenneth B

    2014-10-14

    Plasmonic nanostructures enable light to be concentrated into nanoscale 'hotspots', wherein the intensity of light can be enhanced by orders of magnitude. This plasmonic enhancement significantly boosts the efficiency of nanoscale light-matter interactions, enabling unique linear and nonlinear optical applications. Large enhancements are often observed within narrow gaps or at sharp tips, as predicted by the classical electromagnetic theory. Only recently has it become appreciated that quantum mechanical effects could emerge as the feature size approaches atomic length-scale. Here we experimentally demonstrate, through observations of surface-enhanced Raman scattering, that the emergence of electron tunnelling at optical frequencies limits the maximum achievable plasmonic enhancement. Such quantum mechanical effects are revealed for metallic nanostructures with gap-widths in the single-digit angstrom range by correlating each structure with its optical properties. This work furthers our understanding of quantum mechanical effects in plasmonic systems and could enable future applications of quantum plasmonics.

  7. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng

    2017-03-28

    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  8. The Nanofabrication and Application of Substrates for Surface-Enhanced Raman Scattering

    Directory of Open Access Journals (Sweden)

    Xian Zhang

    2012-01-01

    Full Text Available Surface-enhanced Raman scattering (SERS was discovered in 1974 and impacted Raman spectroscopy and surface science. Although SERS has not been developed to be an applicable detection tool so far, nanotechnology has promoted its development in recent decades. The traditional SERS substrates, such as silver electrode, metal island film, and silver colloid, cannot be applied because of their enhancement factor or stability, but newly developed substrates, such as electrochemical deposition surface, Ag porous film, and surface-confined colloids, have better sensitivity and stability. Surface enhanced Raman scattering is applied in other fields such as detection of chemical pollutant, biomolecules, DNA, bacteria, and so forth. In this paper, the development of nanofabrication and application of surface-enhanced Ramans scattering substrate are discussed.

  9. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  10. Synthesis of Au Nanostars and Their Application as Surface Enhanced Raman Scattering-Activity Tags Inside Living Cells.

    Science.gov (United States)

    Cao, Xiaowei; Shi, Chaowen; Lu, Wenbo; Zhao, Hang; Wang, Man; Tong, Wei; Dong, Jian; Han, Xiaodong; Qian, Weiping

    2015-07-01

    This work presents the synthesis and characterization of Au nanostars (AuNSs) and demonstrates their application as surface enhanced Raman scattering (SERS)-activity tags for cellular imaging and sensing. Nile blue A (NBA) and bovine serum albumin (BSA) were used as Raman reporter molecules and capping materials, respectively. The SERS-activity tags were tested on human lung adenocarcinoma cell (A549) and alveolar type II cell (AT II) and found to present a low level of cytotoxicity and high chemical stability. These SERS-activity tags not only can be applied in multiplexed cellular imaging, including dark field imaging, transmission electron microscopy (TEM) and SERS imaging, but also can be used for cellular sensing. The SERS spectra clearly identified cellular important components such as proteins, nucleic acids, lipids, and carbohydrates. This study also shows that endocytosis is the main channel of tags internalized in cells. The AuNSs exhibiting strong surface enhanced Raman effects are utilized in the design of an efficient, stable SERS-activity tag for intracellular applications.

  11. Application of Raman Microspectroscopic and Raman imaging techniques for cell biological studies

    NARCIS (Netherlands)

    Puppels, G.J.; Puppels, G.J.; Bakker schut, T.C.; Bakker Schut, T.C.; Sijtsema, N.M.; Grond, M.; Grond, M.; Maraboeuf, F.; de Grauw, C.J.; de Grauw, C.J.; Figdor, Carl; Greve, Jan

    1995-01-01

    Raman spectroscopy is being used to study biological molecules for some three decades now. Thanks to continuing advances in instrumentation more and more applications have become feasible in which molecules are studied in situ, and this has enabled Raman spectroscopy to enter the realms of

  12. Development and Application of Raman Microspectroscopic and Raman Imaging Techniques for Cell Biological Studies

    NARCIS (Netherlands)

    PUPPELS, G J; SCHUT, T C B; SIJTSEMA, N M; GROND, M; MARABOEUF, F; DEGRAUW, C G; FIGDOR, C G; GREVE, J

    1995-01-01

    Raman spectroscopy is being used to study biological molecules for some three decades now. Thanks to continuing advances in instrumentation more and more applications have become feasible in which molecules are studied in situ, and this has enabled Raman spectroscopy to enter the realms of

  13. Investigating Nanoscale Electrochemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Zaleski, Stephanie; Wilson, Andrew J; Mattei, Michael; Chen, Xu; Goubert, Guillaume; Cardinal, M Fernanda; Willets, Katherine A; Van Duyne, Richard P

    2016-09-20

    events: single-molecule SERS (SMSERS), superlocalization SERS imaging, and tip-enhanced Raman spectroscopy (TERS). While all of the studies we discuss probe model redox dye systems, the experiments described herein push the study of nanoscale electrochemistry toward the fundamental limit, in terms of both chemical sensitivity and spatial resolution. The second half of this Account discusses current experimental strategies for studying nanoelectrochemistry with SERS techniques, which includes relevant electrochemically and optically active molecules, substrates, and substrate functionalization methods. In particular, we highlight the wide variety of SERS-active substrates and optically active molecules that can be implemented for EC-SERS, as well as the need to carefully characterize both the electrochemistry and resultant EC-SERS response of each new redox-active molecule studied. Finally, we conclude this Account with our perspective on the future directions of studying nanoscale electrochemistry with SERS/TERS, which includes the integration of SECM with TERS and the use of theoretical methods to further describe the fundamental intricacies of single-molecule, single-site electrochemistry at the nanoscale.

  14. Purchase of a Raman and Photoluminescence Imaging System for Characterization of Advanced Electrochemical and Electronic Materials

    Science.gov (United States)

    2016-01-05

    SECURITY CLASSIFICATION OF: Funds were used to purchase a Renishaw inVia Reflex Spectrometer System for Raman and Photoluminescence spectral...Unlimited UU UU UU UU 05-01-2016 15-Aug-2014 14-Aug-2015 Final Report: Purchase of a Raman and Photoluminescence Imaging System for Characterization of...MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 Raman spectroscopy

  15. Raman Spectroscopic Imaging of the Whole Ciona intestinalis Embryo during Development

    Science.gov (United States)

    Nakamura, Mitsuru J.; Hotta, Kohji; Oka, Kotaro

    2013-01-01

    Intracellular composition and the distribution of bio-molecules play central roles in the specification of cell fates and morphogenesis during embryogenesis. Consequently, investigation of changes in the expression and distribution of bio-molecules, especially mRNAs and proteins, is an important challenge in developmental biology. Raman spectroscopic imaging, a non-invasive and label-free technique, allows simultaneous imaging of the intracellular composition and distribution of multiple bio-molecules. In this study, we explored the application of Raman spectroscopic imaging in the whole Ciona intestinalis embryo during development. Analysis of Raman spectra scattered from C. intestinalis embryos revealed a number of localized patterns of high Raman intensity within the embryo. Based on the observed distribution of bio-molecules, we succeeded in identifying the location and structure of differentiated muscle and endoderm within the whole embryo, up to the tailbud stage, in a label-free manner. Furthermore, during cell differentiation, we detected significant differences in cell state between muscle/endoderm daughter cells and daughter cells with other fates that had divided from the same mother cells; this was achieved by focusing on the Raman intensity of single Raman bands at 1002 or 1526 cm−1, respectively. This study reports the first application of Raman spectroscopic imaging to the study of identifying and characterizing differentiating tissues in a whole chordate embryo. Our results suggest that Raman spectroscopic imaging is a feasible label-free technique for investigating the developmental process of the whole embryo of C. intestinalis. PMID:23977129

  16. [Three-dimensional vertically aligned CNTs coated by Ag nanoparticles for surface-enhanced Raman scattering].

    Science.gov (United States)

    Zhang, Xiao-Lei; Zhang, Jie; Fan, Tuo; Ren, Wen-Jie; Lai, Chun-Hong

    2014-09-01

    In order to make surface-enhanced Raman scattering (SERS) substrates contained more "hot spots" in a three-dimensional (3D) focal volume, and can be adsorbed more probe molecules and metal nanoparticles, to obtain stronger Raman spectral signal, a new structure based on vertically aligned carbon nanotubes (CNTs) coated by Ag nanoparticles for surface Raman enhancement is presented. The vertically aligned CNTs are synthesized by chemical vapor deposition (CVD). A silver film is first deposited on the vertically aligned CNTs by magnetron sputtering. The samples are then annealed at different temperature to cause the different size silver nanoparticles to coat on the surface and sidewalls of vertically aligned CNTs. The result of scanning electron microscopy(SEM) shows that Ag nanoparticles are attached onto the sidewalls and tips of the vertically aligned CNTs, as the annealing temperature is different , pitch size, morphology and space between the silver nanoparticles is vary. Rhodamine 6G is served as the probe analyte. Raman spectrum measurement indicates that: the higher the concentration of R6G, the stronger the Raman intensity, but R6G concentration increase with the enhanced Raman intensity varies nonlinearly; when annealing temperature is 450 °C, the average size of silver nanoparticles is about 100 to 120 nm, while annealing temperature is 400 °C, the average size is about 70 nm, and the Raman intensity of 450 °C is superior to the annealing temperature that of 400 °C and 350 °C.

  17. Surface enhanced Raman spectroscopy detection of biomolecules using EBL fabricated nanostructured substrates.

    Science.gov (United States)

    Peters, Robert F; Gutierrez-Rivera, Luis; Dew, Steven K; Stepanova, Maria

    2015-03-20

    Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules is reported. The entire sequence of relevant experimental steps is described, involving the fabrication of nanostructured substrates using electron beam lithography, immobilization of biomolecules on the substrates, and their characterization utilizing surface-enhanced Raman spectroscopy (SERS). Three different designs of nano-biological systems are employed, including protein A, glucose binding protein, and a dopamine binding DNA aptamer. In the latter two cases, the binding of respective ligands, D-glucose and dopamine, is also included. The three kinds of biomolecules are immobilized on nanostructured substrates by different methods, and the results of SERS imaging are reported. The capabilities of SERS to detect vibrational modes from surface-immobilized proteins, as well as to capture the protein-ligand and aptamer-ligand binding are demonstrated. The results also illustrate the influence of the surface nanostructure geometry, biomolecules immobilization strategy, Raman activity of the molecules and presence or absence of the ligand binding on the SERS spectra acquired.

  18. Preclinical Evaluation of Raman Nanoparticle Biodistribution for their Potential Use in Clinical Endoscopy Imaging

    DEFF Research Database (Denmark)

    Zavaleta, Cristina L; Hartman, Keith B; Miao, Zheng

    2011-01-01

    Raman imaging offers unsurpassed sensitivity and multiplexing capabilities. However, its limited depth of light penetration makes direct clinical translation challenging. Therefore, a more suitable way to harness its attributes in a clinical setting would be to couple Raman spectroscopy with endo...

  19. Revealing organization of cellulose in wood cell walls by Raman imaging

    Science.gov (United States)

    Umesh P. Agarwal; Sally A. Ralph

    2007-01-01

    Anisotropy of cellulose organization in mature black spruce wood cell wall was investigated by Raman imaging using a 1 [mu]m lateral-resolution capable confocal Raman microscope. In these studies, wood cross sections (CS) and radial longitudinal sections (LS) that were partially delignified by acid chlorite treatment were used. In the case of CS where latewood cells...

  20. Potential drug – nanosensor conjugates: Raman, infrared absorption, surface – enhanced Raman, and density functional theory investigations of indolic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Pięta, Ewa, E-mail: Ewa.Pieta@ifj.edu.pl [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland); Paluszkiewicz, Czesława [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland); Oćwieja, Magdalena [J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, PL-30239 Krakow (Poland); Kwiatek, Wojciech M. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland)

    2017-05-15

    Highlights: • Molecular fragments involved in the adsorption process were determined. • Formation of hydrogen bonds with the negatively charged gold substrates was observed. • Indole moiety strongly interacts with gold nanosensors. • The synthesized sensors are characterized by high stability and reproducibility. • Chemical mechanism plays a crucial role in the enhancement of the Raman signal. - Abstract: An extremely important aspect of planning cancer treatment is not only the drug efficiency but also a number of challenges associated with the side effects and control of this process. That is why it is worth paying attention to the promising potential of the gold nanoparticles combined with a compound treated as a potential drug. This work presents Raman (RS), infrared absorption (IR) and surface–enhanced Raman scattering (SERS) spectroscopic investigations of N–acetyl–5–methoxytryptamine (melatonin) and α–methyl–DL–tryptophan, regarding as anti breast cancer agents. The experimental spectroscopic analysis was supported by the quantum-chemical calculations based on the B3LYP hybrid density functional theory (DFT) at the B3LYP 6–311G(d,p) level of theory. The studied compounds were adsorbed onto two colloidal gold nanosensors synthesized by a chemical reduction method using sodium borohydride (SB) and trisodium citrate (TC), respectively. Its morphology characteristics were obtained using transmission electron microscopy (TEM). It has been suggested that the NH moiety from the aromatic ring, a well-known proton donor, causes the formation of hydrogen bonds with the negatively charged gold surface.

  1. Flexible Microsphere-Embedded Film for Microsphere-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Xing, Cheng; Yan, Yinzhou; Feng, Chao; Xu, Jiayu; Dong, Peng; Guan, Wei; Zeng, Yong; Zhao, Yan; Jiang, Yijian

    2017-09-27

    Dielectric microspheres with extraordinary microscale optical properties, such as photonic nanojets, optical whispering-gallery modes (WGMs), and directional antennas, have drawn interest in many research fields. Microsphere-enhanced Raman spectroscopy (MERS) is an alternative approach for enhanced Raman detection by dielectric microstructures. Unfortunately, fabrication of microsphere monolayer arrays is the major challenge of MERS for practical applications on various specimen surfaces. Here we report a microsphere-embedded film (MF) by immersing a highly refractive microsphere monolayer array in the poly(dimethylsiloxane) (PDMS) film as a flexible MERS sensing platform for one- to three-dimensional (1D to 3D) specimen surfaces. The directional antennas and wave-guided whispering-gallery modes (WG-WGMs) contribute to the majority of Raman enhancement by the MFs. Moreover, the MF can be coupled with surface-enhanced Raman spectroscopy (SERS) to provide an extra >10-fold enhancement. The limit of detection is therefore improved for sensing of crystal violet (CV) and Sudan I molecules in aqueous solutions at concentrations down to 10 -7 M. A hybrid dual-layer microsphere enhancer, constructed by depositing a MF onto a microsphere monolayer array, is also demonstrated, wherein the WG-WGMs become dominant and boost the enhancement ratio >50-fold. The present work opens up new opportunities for design of cost-effective and flexible MERS sensing platforms as individual or associated techniques toward practical applications in ultrasensitive Raman detection.

  2. Surface-Enhanced Raman Spectroscopy of Carbon Nanomembranes from Aromatic Self-Assembled Monolayers.

    Science.gov (United States)

    Zhang, Xianghui; Mainka, Marcel; Paneff, Florian; Hachmeister, Henning; Beyer, André; Gölzhäuser, Armin; Huser, Thomas

    2018-02-27

    Surface-enhanced Raman scattering spectroscopy (SERS) was employed to investigate the formation of self-assembled monolayers (SAMs) of biphenylthiol, 4'-nitro-1,1'-biphenyl-4-thiol, and p-terphenylthiol on Au surfaces and their structural transformations into carbon nanomembranes (CNMs) induced by electron irradiation. The high sensitivity of SERS allows us to identify two types of Raman scattering in electron-irradiated SAMs: (1) Raman-active sites exhibit similar bands as those of pristine SAMs in the fingerprint spectral region, but with indications of an amorphization process and (2) Raman-inactive sites show almost no Raman-scattering signals, except a very weak and broad D band, indicating a lack of structural order but for the presence of graphitic domains. Statistical analysis showed that the ratio of the number of Raman-active sites to the total number of measurement sites decreases exponentially with increasing the electron irradiation dose. The maximum degree of cross-linking ranged from 97 to 99% for the three SAMs. Proof-of-concept experiments were conducted to demonstrate potential applications of Raman-inactive CNMs as a supporting membrane for Raman analysis.

  3. Long range image enhancement

    CSIR Research Space (South Africa)

    Duvenhage, B

    2015-11-01

    Full Text Available the surveillance system performance. This paper discusses an image processing method that tracks the behaviour of the PSF and then de-warps the image to reduce the disruptive effects of turbulence. Optical flow, an average image filter and a simple unsharp mask...

  4. Multifocus confocal Raman microspectroscopy for fast multimode vibrational imaging of living cells.

    Science.gov (United States)

    Okuno, Masanari; Hamaguchi, Hiro-o

    2010-12-15

    We have developed a multifocus confocal Raman microspectroscopic system for the fast multimode vibrational imaging of living cells. It consists of an inverted microscope equipped with a microlens array, a pinhole array, a fiber bundle, and a multichannel Raman spectrometer. Forty-eight Raman spectra from 48 foci under the microscope are simultaneously obtained by using multifocus excitation and image-compression techniques. The multifocus confocal configuration suppresses the background generated from the cover glass and the cell culturing medium so that high-contrast images are obtainable with a short accumulation time. The system enables us to obtain multimode (10 different vibrational modes) vibrational images of living cells in tens of seconds with only 1 mW laser power at one focal point. This image acquisition time is more than 10 times faster than that in conventional single-focus Raman microspectroscopy.

  5. Retinex enhancement of infrared images.

    Science.gov (United States)

    Li, Ying; He, Renjie; Xu, Guizhi; Hou, Changzhi; Sun, Yunyan; Guo, Lei; Rao, Liyun; Yan, Weili

    2008-01-01

    With the ability of imaging the temperature distribution of body, infrared imaging is promising in diagnostication and prognostication of diseases. However the poor quality of the raw original infrared images prevented applications and one of the essential problems is the low contrast appearance of the imagined object. In this paper, the image enhancement technique based on the Retinex theory is studied, which is a process that automatically retrieve the visual realism to images. The algorithms, including Frackle-McCann algorithm, McCann99 algorithm, single-scale Retinex algorithm, multi-scale Retinex algorithm and multi-scale Retinex algorithm with color restoration, are experienced to the enhancement of infrared images. The entropy measurements along with the visual inspection were compared and results shown the algorithms based on Retinex theory have the ability in enhancing the infrared image. Out of the algorithms compared, MSRCR demonstrated the best performance.

  6. Using Raman Spectroscopy and Surface-Enhanced Raman Scattering to Identify Colorants in Art: An Experiment for an Upper-Division Chemistry Laboratory

    Science.gov (United States)

    Mayhew, Hannah E.; Frano, Kristen A.; Svoboda, Shelley A.; Wustholz, Kristin L.

    2015-01-01

    Surface-enhanced Raman scattering (SERS) studies of art represent an attractive way to introduce undergraduate students to concepts in nanoscience, vibrational spectroscopy, and instrumental analysis. Here, we present an undergraduate analytical or physical chemistry laboratory wherein a combination of normal Raman and SERS spectroscopy is used to…

  7. Surface enhanced raman scattering at Ag-Pyridine interface by use of long range surface plasmon

    International Nuclear Information System (INIS)

    Baik, Moon Gu; Ko, Eu; Kwan, Do Kyeong; Lee, Ja Hyung; Chang, Joon Sung

    1990-01-01

    Surface-enhanced Raman scattering (SERS) experiment of pyridine (C 5 H 5 N) has been performed at silverpyridine interface by use of long range surface plasmon (LRSP) which is generated in the Sarid-type attenuated total reflection (ATR) structure consisting of prism, dielectic, metal and dielectic media. Generation of LRSP has been confirmed by observing the propagation of the LRSP. Raman signal of pyridine adsorbed on the silver surface in the above layered structure has been observed and compared with the bulk Raman signal and SERS signal from the chemically adsorbed pyridine. SERS experiment by use of LRSP has not yet reported to the best of our knowledge. (Author)

  8. Click chemistry based biomolecular conjugation monitoring using surface-enhanced Raman spectroscopy mapping

    DEFF Research Database (Denmark)

    Palla, Mirko; Kumar, Shiv; Li, Zengmin

    2016-01-01

    We describe here a novel surface-enhanced Raman spectroscopy (SERS) based technique for monitoring the conjugation of small molecules by the well-known click reaction between an alkyne and azido moiety on the partner molecules. The monitoring principle is based on the loss of the characteristic...... alkyne/azide Raman signal with triazole formation in the reaction as a function of time. Since these universal Raman reporter groups are specific for click reactions, this method may facilitate a broad range of applications for monitoring the conjugation efficiency of molecules in diverse areas...

  9. Plasmonic nanopillar structures for surface-enhanced raman scattering applications

    DEFF Research Database (Denmark)

    Rindzevicius, Tomas; Schmidt, Michael Stenbæk; Wu, Kaiyu

    2016-01-01

    have been utilized in surfaceenhanced Raman spectroscopy (SERS) for biological and chemical sensing. We present Au nanopillar (NP) SERS structures that are excellent for molecular detection. The NP structures can be fabricated using a simple two-step process. We analyze NP optical properties...

  10. Application of silver nanoparticles in the detection of SYBR Green I by surface enhanced Raman and surface-enhanced fluorescence

    Science.gov (United States)

    Guo, Wei; Wu, Jian; Wang, Chunyan; Zhang, Tian; Chen, Tao

    2018-05-01

    Silver nanomaterials have remarkable application in biomedical detection due to their unique surface plasmon resonance (SPR) characteristics. It can be used for surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF). Current research elaborates a technique for improvement of SYBR Green I detection obtained from surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) by silver nanoparticles with the average size about 70 nm. Primarily, SYBR Green I is an important fluorescent dye used in polymerase chain reaction (PCR). It is found that both Raman and fluorescence can be used for detection of this dye. Furthermore, the enhanced efficiency of the Raman and fluorescence by SERS and SEF is observed in this study, the enhancement factor for Raman signals is 3.2 × 103, and the fluorescence intensity bincreased two times by SEF. The quantitative detection of SYBR Green I by SERS and SEF can be achieved. The present work can be used to improve the detection of SYBR Green I by SERS and SEF. It would also be employed for high-sensitive detection of other materials in the future.

  11. Raman Imaging of Plant Cell Walls in Sections of Cucumis sativus.

    Science.gov (United States)

    Zeise, Ingrid; Heiner, Zsuzsanna; Holz, Sabine; Joester, Maike; Büttner, Carmen; Kneipp, Janina

    2018-01-25

    Raman microspectra combine information on chemical composition of plant tissues with spatial information. The contributions from the building blocks of the cell walls in the Raman spectra of plant tissues can vary in the microscopic sub-structures of the tissue. Here, we discuss the analysis of 55 Raman maps of root, stem, and leaf tissues of Cucumis sativus , using different spectral contributions from cellulose and lignin in both univariate and multivariate imaging methods. Imaging based on hierarchical cluster analysis (HCA) and principal component analysis (PCA) indicates different substructures in the xylem cell walls of the different tissues. Using specific signals from the cell wall spectra, analysis of the whole set of different tissue sections based on the Raman images reveals differences in xylem tissue morphology. Due to the specifics of excitation of the Raman spectra in the visible wavelength range (532 nm), which is, e.g., in resonance with carotenoid species, effects of photobleaching and the possibility of exploiting depletion difference spectra for molecular characterization in Raman imaging of plants are discussed. The reported results provide both, specific information on the molecular composition of cucumber tissue Raman spectra, and general directions for future imaging studies in plant tissues.

  12. A portable confocal hyperspectral microscope without any scan or tube lens and its application in fluorescence and Raman spectral imaging

    Science.gov (United States)

    Li, Jingwei; Cai, Fuhong; Dong, Yongjiang; Zhu, Zhenfeng; Sun, Xianhe; Zhang, Hequn; He, Sailing

    2017-06-01

    In this study, a portable confocal hyperspectral microscope is developed. In traditional confocal laser scanning microscopes, scan lens and tube lens are utilized to achieve a conjugate relationship between the galvanometer and the back focal plane of the objective, in order to achieve a better resolution. However, these lenses make it difficult to scale down the volume of the system. In our portable confocal hyperspectral microscope (PCHM), the objective is placed directly next to the galvomirror. Thus, scan lens and tube lens are not included in our system and the size of this system is greatly reduced. Furthermore, the resolution is also acceptable in many biomedical and food-safety applications. Through reducing the optical length of the system, the signal detection efficiency is enhanced. This is conducive to realizing both the fluorescence and Raman hyperspectral imaging. With a multimode fiber as a pinhole, an improved image contrast is also achieved. Fluorescent spectral images for HeLa cells/fingers and Raman spectral images of kumquat pericarp are present. The spectral resolution and spatial resolutions are about 0.4 nm and 2.19 μm, respectively. These results demonstrate that this portable hyperspectral microscope can be used in in-vivo fluorescence imaging and in situ Raman spectral imaging.

  13. Frontiers of surface-enhanced Raman scattering single nanoparticles and single cells

    CERN Document Server

    Ozaki, Yukihiro; Aroca, Ricardo

    2014-01-01

    A comprehensive presentation of Surface-Enhanced Raman Scattering (SERS) theory, substrate fabrication, applications of SERS to biosystems, chemical analysis, sensing and fundamental innovation through experimentation. Written by internationally recognized editors and contributors. Relevant to all those within the scientific community dealing with Raman Spectroscopy, i.e. physicists, chemists, biologists, material scientists, physicians and biomedical scientists. SERS applications are widely expanding and the technology is now used in the field of nanotechnologies, applications to biosystems, nonosensors, nanoimaging and nanoscience.

  14. Calibration and testing of a Raman hyperspectral imaging system to reveal powdered food adulteration.

    Science.gov (United States)

    Lohumi, Santosh; Lee, Hoonsoo; Kim, Moon S; Qin, Jianwei; Kandpal, Lalit Mohan; Bae, Hyungjin; Rahman, Anisur; Cho, Byoung-Kwan

    2018-01-01

    The potential adulteration of foodstuffs has led to increasing concern regarding food safety and security, in particular for powdered food products where cheap ground materials or hazardous chemicals can be added to increase the quantity of powder or to obtain the desired aesthetic quality. Due to the resulting potential health threat to consumers, the development of a fast, label-free, and non-invasive technique for the detection of adulteration over a wide range of food products is necessary. We therefore report the development of a rapid Raman hyperspectral imaging technique for the detection of food adulteration and for authenticity analysis. The Raman hyperspectral imaging system comprises of a custom designed laser illumination system, sensing module, and a software interface. Laser illumination system generates a 785 nm laser line of high power, and the Gaussian like intensity distribution of laser beam is shaped by incorporating an engineered diffuser. The sensing module utilize Rayleigh filters, imaging spectrometer, and detector for collection of the Raman scattering signals along the laser line. A custom-built software to acquire Raman hyperspectral images which also facilitate the real time visualization of Raman chemical images of scanned samples. The developed system was employed for the simultaneous detection of Sudan dye and Congo red dye adulteration in paprika powder, and benzoyl peroxide and alloxan monohydrate adulteration in wheat flour at six different concentrations (w/w) from 0.05 to 1%. The collected Raman imaging data of the adulterated samples were analyzed to visualize and detect the adulterant concentrations by generating a binary image for each individual adulterant material. The results obtained based on the Raman chemical images of adulterants showed a strong correlation (R>0.98) between added and pixel based calculated concentration of adulterant materials. This developed Raman imaging system thus, can be considered as a powerful

  15. Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators

    Science.gov (United States)

    Anderson, Mark S.

    2013-01-01

    The motivation of this work was to have robust spectroscopic sensors for sensitive detection and chemical analysis of organic and molecular compounds. The solution is to use silica sphere optical resonators to provide surface-enhanced spectroscopic signal. Whispering-gallery mode (WGM) resonators made from silica microspheres were used for surface-enhanced Raman scattering (SERS) without coupling to a plasmonic mechanism. Large Raman signal enhancement is observed by exclusively using 5.08-micron silica spheres with 785-nm laser excitation. The advantage of this non-plasmonic approach is that the active substrate is chemically inert silica, thermally stable, and relatively simple to fabricate. The Raman signal enhancement is broadly applicable to a wide range of molecular functional groups including aliphatic hydrocarbons, siloxanes, and esters. Applications include trace organic analysis, particularly for in situ planetary instruments that require robust sensors with consistent response.

  16. In situ identification of paper chromatogram spots by surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tran, C D

    1984-01-01

    The use of silver hydrosols to enhance the Raman scattering of paper chromatogram spots has been used successfully. This enhancement technique, which is dependent on the interaction between the substrate, silver particles, and paper fibers, has been applied to detection and identification of ng amounts of crystal violet, malachite green, and basic fuchsin with an argon laser of only 4 mW. This technique enhances the resonance of the Raman scattering so that the Raman cross sections of the spots are approximately 9 to 10 orders of magnitude higher than those observed for non-enhanced systems. The limit of detection of the techniques is defined as the amount of dye spot that yields a signal to noise ratio of 2 when excited with the 4MeV.

  17. Enhanced Raman scattering assisted by ultrahigh order modes of the double metal cladding waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian; Huang, Liming; Jin, Yonglong; Fang, Jinghuai, E-mail: cyin.phys@gmail.com, E-mail: fjhuai@ntu.edu.cn [Physics Department, Nantong University, No. 9, Seyuan Road, Nantong, Jiangsu 226007 (China); Yin, Cheng, E-mail: cyin.phys@gmail.com, E-mail: fjhuai@ntu.edu.cn [Jiangsu Key Laboratory of Power Transmission and Distribution Equipment Technology, Hohai University, Changzhou 213022 (China); Huang, Meizhen [Department of Instrument Science and Engineering, Shanghai Jiaotong University, No. 800, DongChuan Road, Shanghai 200240 (China)

    2014-10-20

    Distinguished from the usual strategy to enhance the Raman scattering such as creating hot spots in the surface-enhanced Raman scattering, this paper takes a quite different approach based on the double metal cladding waveguide. The target analyte is located in the guiding layer of sub-millimeter scale, where several ultrahigh order modes with high intensity are simultaneously excited via a focused laser beam. The experimental setup is simple, and both simulation and experimental results confirm the enhancement mechanism of these oscillating modes. Other appealing features include the large detection area and the ability to excite guided modes via both polarizations. This scheme can be applied to large molecules detection and readily integrated with other Raman enhancement techniques.

  18. Ultrathin free-standing close-packed gold nanoparticle films: Conductivity and Raman scattering enhancement

    Science.gov (United States)

    Yu, Qing; Huang, Hongwen; Peng, Xinsheng; Ye, Zhizhen

    2011-09-01

    -treatment temperature, and thickness, respectively. The conductivity of the film prepared from 20 nm gold nanoparticles is higher than that of the film prepared from 40 nm gold nanoparticle by filtering the same filtration volume of their solution, respectively. Their conductivities are comparable to that of the 220 nm thick ITO film. Furthermore, these films demonstrated an average surface Raman scattering enhancement up to 6.59 × 105 for Rhodamine 6 G molecules on the film prepared from 40 nm gold nanoparticles. Due to a lot of nano interspaces generated from the close-packed structures, two abnormal enhancements and relative stronger intensities of the asymmetrical vibrations at 1534 and 1594 cm-1 of R6G were observed, respectively. These robust free-standing gold nanoparticle films could be easily transferred onto various solid substrates and hold the potential application for electrodes and surface enhanced Raman detectors. This method is applicable for preparation of other nanoparticle free-standing thin films. Electronic supplementary information (ESI) available: Figure S1, the SEM images and photograph of the films prepared from 10 ml, 20 nm gold nanoparticles. Scheme S1, the vibrations of 1534 and 1594 cm-1 of R6G. See DOI: 10.1039/c1nr10578g

  19. Label-Free Raman Imaging to Monitor Breast Tumor Signatures

    Science.gov (United States)

    Ciubuc, John

    Methods built on Raman spectroscopy have shown major potential in describing and discriminating between malignant and benign specimens. Accurate, real-time medical diagnosis benefits in substantial improvements through this vibrational optical method. Not only is acquisition of data possible in milliseconds and analysis in minutes, Raman allows concurrent detection and monitoring of all biological components. Besides validating a significant Raman signature distinction between non-tumorigenic (MCF-10A) and tumorigenic (MCF-7) breast epithelial cells, this study reveals a label-free method to assess overexpression of epidermal growth factor receptors (EGFR) in tumor cells. EGFR overexpression sires Raman features associated with phosphorylated threonine and serine, and modifications of DNA/RNA characteristics. Investigations by gel electrophoresis reveal EGF induction of phosphorylated Akt, agreeing with the Raman results. The analysis presented is a vital step toward Raman-based evaluation of EGF receptors in breast cancer cells. With the goal of clinically applying Raman-guided methods for diagnosis of breast tumors, the current results lay the basis for proving label-free optical alternatives in making prognosis of the disease.

  20. Antenna Design for Directivity-Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Aftab Ahmed

    2012-01-01

    Full Text Available Antenna performance can be described by two fundamental parameters: directivity and radiation efficiency. Here, we demonstrate nanoantenna designs in terms of improved directivity. Performance of the antennas is demonstrated in Raman scattering experiments. The radiated beam is directed out of the plane by using a ground plane reflector for easy integration with commercial microscopes. Parasitic elements and parabolic and waveguide nanoantennas with a ground plane are explored. The nanoantennas were fabricated by a series of electron beam evaporation steps and focused ion beam milling. As we have shown previously, the circular waveguide nanoantenna boosts the measured Raman signal by 5.5x with respect to a dipole antenna over a ground plane; here, we present the design process that led to the development of that circular waveguide nanoantenna. This work also shows that the parabolic nanoantenna produces a further fourfold improvement in the measured Raman signal with respect to a circular waveguide nanoantenna. The present designs are nearly optimal in the sense that almost all the beam power is coupled into the numerical aperture of the microscope. These designs can find applications in microscopy, spectroscopy, light-emitting devices, photovoltaics, single-photon sources, and sensing.

  1. Image enhancement through deconvolution

    International Nuclear Information System (INIS)

    Zhang, Xiaodong; Jacobsen, C.; Williams, S.

    1993-01-01

    Several groups have been developing X-ray microscopes for studies of biological and materials specimens at suboptical resolution. The XIA Scanning Transmission X-ray Microscope at Brookhaven National Laboratory has achieved 55 nm Rayleigh resolution, and is limited by the 45 nm finest zone width of the zone plate used to focus the X-rays. In principle, features as small as half the outermost zone width, or 23 nm, can be observed in the microscope, though with reduced contrast in the image. One approach to recover the object from the image is to deconvolve the image with the Point Spread Function (PSF) of the optic system. Towards this end, the magnitude of the Fourier transform of the PSF, the Modulation Transfer Function, has been experimentally determined and agrees reasonably well with the calculations using the known parameters of the microscope. To minimize artifacts in the deconvolved images, large signal-to-noise ratios are required in the original image, and high frequency filters can be used to reduce the noise at the expense of resolution. In this way the authors are able to recover the original contrast of high resolution features in the images

  2. Tip Enhanced Raman Spectroscopy of Rhodamine 6G on nanostructured gold substrate

    KAUST Repository

    Moretti, Manola

    2015-05-01

    A new concept based setup for Tip Enhanced Raman Scattering measurement assisted by gold nanostructure is presented, that can provide a platform for gap-mode enhancement of the signal at the single molecule level conjugated with controlled spatial localization of the molecule under investigation and a method to determine the diffraction limit properties of the tip. In essence, this effect is obtained illuminating a gold coated AFM tip which is raster scanned over a nanostructured gold substrate, after chemisorption of a Raman active molecule. We expect that the near-field Raman enhancement would be given by the gap-mode effect of the two facing nano-features. Thanks to the nanostructured substrate, we verify that the resolution of the Raman mapping signal is well below the diffraction limit given by the combination of the optics geometry and the laser wavelength. We show that the gap-mode TERS can generate an estimated field- enhancement (g) of ~20 in localized areas of the sample and we demonstrate the ability to spatially define the molecule position (by Raman mapping) at the tens of nanometers scale. © 2015 Elsevier Ltd.

  3. Tip Enhanced Raman Spectroscopy of Rhodamine 6G on nanostructured gold substrate

    KAUST Repository

    Moretti, Manola; Das, Gobind; Torre, Bruno; Allione, Marco; Di Fabrizio, Enzo M.

    2015-01-01

    A new concept based setup for Tip Enhanced Raman Scattering measurement assisted by gold nanostructure is presented, that can provide a platform for gap-mode enhancement of the signal at the single molecule level conjugated with controlled spatial localization of the molecule under investigation and a method to determine the diffraction limit properties of the tip. In essence, this effect is obtained illuminating a gold coated AFM tip which is raster scanned over a nanostructured gold substrate, after chemisorption of a Raman active molecule. We expect that the near-field Raman enhancement would be given by the gap-mode effect of the two facing nano-features. Thanks to the nanostructured substrate, we verify that the resolution of the Raman mapping signal is well below the diffraction limit given by the combination of the optics geometry and the laser wavelength. We show that the gap-mode TERS can generate an estimated field- enhancement (g) of ~20 in localized areas of the sample and we demonstrate the ability to spatially define the molecule position (by Raman mapping) at the tens of nanometers scale. © 2015 Elsevier Ltd.

  4. Dielectrophoretic positioning of single nanoparticles on atomic force microscope tips for tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Leiterer, Christian; Deckert-Gaudig, Tanja; Singh, Prabha; Wirth, Janina; Deckert, Volker; Fritzsche, Wolfgang

    2015-05-01

    Tip-enhanced Raman spectroscopy, a combination of Raman spectroscopy and scanning probe microscopy, is a powerful technique to detect the vibrational fingerprint of molecules at the nanometer scale. A metal nanoparticle at the apex of an atomic force microscope tip leads to a large enhancement of the electromagnetic field when illuminated with an appropriate wavelength, resulting in an increased Raman signal. A controlled positioning of individual nanoparticles at the tip would improve the reproducibility of the probes and is quite demanding due to usually serial and labor-intensive approaches. In contrast to commonly used submicron manipulation techniques, dielectrophoresis allows a parallel and scalable production, and provides a novel approach toward reproducible and at the same time affordable tip-enhanced Raman spectroscopy tips. We demonstrate the successful positioning of an individual plasmonic nanoparticle on a commercial atomic force microscope tip by dielectrophoresis followed by experimental proof of the Raman signal enhancing capabilities of such tips. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers

    KAUST Repository

    Perozziello, Gerardo

    2015-12-11

    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels- where the cells can flow one-by-one -, allowing single cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm of the each cell. Experiments are performed on red blood cells (RBCs), peripheral blood lymphocytes (PBLs) and myelogenous leukemia tumor cells (K562). © 2015 Optical Society of America.

  6. Probing the evaporation of ternary ethanol-methanol-water droplets by cavity enhanced Raman scattering.

    Science.gov (United States)

    Howle, Chris R; Homer, Chris J; Hopkins, Rebecca J; Reid, Jonathan P

    2007-10-21

    Cavity enhanced Raman scattering is used to characterise the evolving composition of ternary aerosol droplets containing methanol, ethanol and water during evaporation into a dry nitrogen atmosphere. Measurements made using non-linear stimulated Raman scattering from these ternary alcohol-water droplets allow the in situ determination of the concentration of the two alcohol components with high accuracy. The overlapping spontaneous Raman bands of the two alcohol components, arising from C-H stretching vibrational modes, are spectrally-resolved in stimulated Raman scattering measurements. We also demonstrate that the evaporation measurements are consistent with a quasi-steady state evaporation model, which can be used to interpret the evaporation dynamics occurring at a range of pressures at a particular evaporation time.

  7. Micro-Raman Imaging for Biology with Multivariate Spectral Analysis

    KAUST Repository

    Malvaso, Federica

    2015-01-01

    . The aim of the following thesis work is to analyze Raman maps related to three pairs of different cells, highlighting differences and similarities through multivariate algorithms. The first pair of analyzed cells are human embryonic stem cells (h

  8. Effect of surface density silver nanoplate films toward surface-enhanced Raman scattering enhancement for bisphenol A detection

    Science.gov (United States)

    Bakar, N. A.; Salleh, M. M.; Umar, A. A.; Shapter, J. G.

    2018-03-01

    This paper reports a study on surface-enhanced Raman scattering (SERS) phenomenon of triangular silver nanoplate (NP) films towards bisphenol A (BPA) detection. The NP films were prepared using self-assembly technique with four different immersion times; 1 hour, 2 hours, 5 hours, and 8 hours. The SERS measurement was studied by observing the changes in Raman spectra of BPA after BPA absorbed on the NP films. It was found that the Raman intensity of BPA peaks was enhanced by using the prepared SERS substrates. This is clearly indicated that these SERS silver substrates are suitable to sense industrial chemical and potentially used as SERS detector. However, the rate of SERS enhancement is depended on the distribution of NP on the substrate surface.

  9. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  10. Tip-Enhanced Raman Scattering Microscopy: A Step toward Nanoscale Control of Intrinsic Molecular Properties

    Science.gov (United States)

    Yano, Taka-aki; Hara, Masahiko

    2018-06-01

    Tip-enhanced Raman scattering microscopy, a family of scanning probe microscopy techniques, has been recognized as a powerful surface analytical technique with both single-molecule sensitivity and angstrom-scale spatial resolution. This review covers the current status of tip-enhanced Raman scattering microscopy in surface and material nanosciences, including a brief history, the basic principles, and applications for the nanoscale characterization of a variety of nanomaterials. The focus is on the recent trend of combining tip-enhanced Raman scattering microscopy with various external stimuli such as pressure, voltage, light, and temperature, which enables the local control of the molecular properties and functions and also enables chemical reactions to be induced on a nanometer scale.

  11. Unveiling the Aggregation of Lycopene in Vitro and in Vivo: UV-Vis, Resonance Raman, and Raman Imaging Studies.

    Science.gov (United States)

    Ishigaki, Mika; Meksiarun, Phiranuphon; Kitahama, Yasutaka; Zhang, Leilei; Hashimoto, Hideki; Genkawa, Takuma; Ozaki, Yukihiro

    2017-08-31

    The present study investigates the structure of lycopene aggregates both in vitro and in vivo using ultraviolet-visible (UV-vis) and Raman spectroscopies. The electronic absorption bands of the J- and H-aggregates in vitro shift to lower and higher energies, respectively, compared to that of the lycopene monomer. Along with these results, the frequencies of the ν 1 Raman bands were shifted to lower and higher frequencies, respectively. By plotting the frequencies of the ν 1 Raman band against the S 0 → S 2 transition energy, a linear relationship between the data set with different aggregation conformations can be obtained. Therefore, the band positions depending on the different conformations can be explained based on the idea that the effective conjugated C═C chain lengths within lycopene molecules are different due to the environmental effect (site-shift effect) caused by the aggregation conformation. Applying this knowledge to the in vivo measurement of a tomato fruit sample, the relationship between the aggregation conformation of lycopene and the spectral patterns observed in the UV-vis as well as Raman spectra in different parts of tomato fruits was discussed in detail. The results showed that the concentration of lycopene (particularly that of the J-aggregate) specifically increased, whereas that of chlorophyll decreased, with ripening. Furthermore, Raman imaging indicated that lycopene with different aggregate conformations was distributed inhomogeneously, even within one sample. The layer formation in tomato tissues with high concentrations of J- and H-aggregates was successfully visualized. In this manner, the presence of lycopene distributions with different aggregate conformations was unveiled in vivo.

  12. Formation of gold nanorods and gold nanorod films for surface-enhanced Raman scattering spectroscopy

    International Nuclear Information System (INIS)

    Trotsyuk, L.L.; Kulakovich, O.S.; Shabunya-Klyachkovskaya, E.V.; Gaponenko, S.V.; Vashchenko, S.V.

    2016-01-01

    The formation of gold nanorods as well as thin films prepared via electrostatic deposition of gold nanorods has been investigated. The obtained gold nanorods films have been used as substrates for the surface-enhanced Raman scattering analysis of sulfur-free organic molecules mitoxantrone and malachite green as well as inorganic malachite microcrystals for the first time. The additional modification of films with L-cysteine allows one to significantly extend the use of gold nanorods for the surface-enhanced Raman scattering analysis. (authors)

  13. Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Ho, Ho Pui; Lee, Rebecca K.Y.

    2009-01-01

    We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree of repro......We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree...

  14. Rapid thyroid dysfunction screening based on serum surface-enhanced Raman scattering and multivariate statistical analysis

    Science.gov (United States)

    Tian, Dayong; Lü, Guodong; Zhai, Zhengang; Du, Guoli; Mo, Jiaqing; Lü, Xiaoyi

    2018-01-01

    In this paper, serum surface-enhanced Raman scattering and multivariate statistical analysis are used to investigate a rapid screening technique for thyroid function diseases. At present, the detection of thyroid function has become increasingly important, and it is urgently necessary to develop a rapid and portable method for the detection of thyroid function. Our experimental results show that, by using the Silmeco-based enhanced Raman signal, the signal strength greatly increases and the characteristic peak appears obviously. It is also observed that the Raman spectra of normal and anomalous thyroid function human serum are significantly different. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was used to diagnose thyroid dysfunction, and the diagnostic accuracy was 87.4%. The use of serum surface-enhanced Raman scattering technology combined with PCA-LDA shows good diagnostic performance for the rapid detection of thyroid function. By means of Raman technology, it is expected that a portable device for the rapid detection of thyroid function will be developed.

  15. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

    Science.gov (United States)

    Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

    2016-08-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm-1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10-12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands.

  16. Label-Free Raman Hyperspectral Imaging of Single Cells Cultured on Polymer Substrates.

    Science.gov (United States)

    Sinjab, Faris; Sicilia, Giovanna; Shipp, Dustin W; Marlow, Maria; Notingher, Ioan

    2017-12-01

    While Raman hyperspectral imaging has been widely used for label-free mapping of biomolecules in cells, these measurements require the cells to be cultured on weakly Raman scattering substrates. However, many applications in biological sciences and engineering require the cells to be cultured on polymer substrates that often generate large Raman scattering signals. Here, we discuss the theoretical limits of the signal-to-noise ratio in the Raman spectra of cells in the presence of polymer signals and how optical aberrations may affect these measurements. We show that Raman spectra of cells cultured on polymer substrates can be obtained using automatic subtraction of the polymer signals and demonstrate the capabilities of these methods in two important applications: tissue engineering and in vitro toxicology screening of drugs. Apart from their scientific and technological importance, these applications are examples of the two most common measurement configurations: (1) cells cultured on an optically thick polymer substrate measured using an immersion/dipping objective; and (2) cells cultured on a transparent polymer substrate and measured using an inverted optical microscope. In these examples, we show that Raman hyperspectral data sets with sufficient quality can be successfully acquired to map the distribution of common biomolecules in cells, such as nucleic acids, proteins, and lipids, as well as detecting the early stages of apoptosis. We also discuss strategies for further improvements that could expand the application of Raman hyperspectral imaging on polymer substrates even further in biomedical sciences and engineering.

  17. Raman enhancement by graphene-Ga2O3 2D bilayer film.

    Science.gov (United States)

    Zhu, Yun; Yu, Qing-Kai; Ding, Gu-Qiao; Xu, Xu-Guang; Wu, Tian-Ru; Gong, Qian; Yuan, Ning-Yi; Ding, Jian-Ning; Wang, Shu-Min; Xie, Xiao-Ming; Jiang, Mian-Heng

    2014-01-28

    2D β-Ga2O3 flakes on a continuous 2D graphene film were prepared by a one-step chemical vapor deposition on liquid gallium surface. The composite was characterized by optical microscopy, scanning electron microscopy, Raman spectroscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that Ga2O3 flakes grew on the surface of graphene film during the cooling process. In particular, tenfold enhancement of graphene Raman scattering signal was detected on Ga2O3 flakes, and XPS indicates the C-O bonding between graphene and Ga2O3. The mechanism of Raman enhancement was discussed. The 2D Ga2O3-2D graphene structure may possess potential applications.

  18. Raman signal enhancement by multiple beam excitation and its application for the detection of chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sakshi [Laser Science and Technology Centre, Metcalfe House, Delhi 110054 (India); Instrument Design and Development Centre, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmad, Azeem; Mehta, Dalip S., E-mail: mehtads@physics.iitd.ac.in [Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Gambhir, Vijayeta; Reddy, Martha N. [Laser Science and Technology Centre, Metcalfe House, Delhi 110054 (India)

    2015-08-31

    In a typical Raman based sensor, a single laser beam is used for exciting the sample and the backscattered or forward scattered light is collected using collection optics and is analyzed by a spectrometer. We have investigated that by means of exciting the sample with multiple beams, i.e., by dividing the same input power of the single beam into two or three or more beams and exciting the sample from different angles, the Raman signal enhances significantly. Due to the presence of multiple beams passing through the same volume of the sample, an interference pattern is formed and the volume of interaction of excitation beams with the sample increases. By means of this geometry, the enhancement in the Raman signal is observed and it was found that the signal strength increases linearly with the increase in number of excitation beams. Experimental results of this scheme for excitation of the samples are reported for explosive detection at a standoff distance.

  19. Gold Nanostructures for Surface-Enhanced Raman Spectroscopy, Prepared by Electrodeposition in Porous Silicon

    Directory of Open Access Journals (Sweden)

    Yukio H. Ogata

    2011-04-01

    Full Text Available Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope observation of the gold deposited porous silicon. Gold nanorod arrays with different rod lengths were prepared, and their surface-enhanced Raman scattering properties were investigated. We found that the absorption peak due to the surface plasmon resonance can be tuned by changing the length of the nanorods. The optimum length of the gold nanorods was ~600 nm for surface-enhanced Raman spectroscopy using a He-Ne laser. The reason why the optimum length of the gold nanorods was 600 nm was discussed by considering the relationship between the absorption peak of surface plasmon resonance and the wavelength of the incident laser for Raman scattering.

  20. Raman Spectroscopy for Homeland Security Applications

    Directory of Open Access Journals (Sweden)

    Gregory Mogilevsky

    2012-01-01

    Full Text Available Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS, resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS. Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.

  1. Surface-enhanced Raman scattering on periodic metal nanotips with tunable sharpness

    International Nuclear Information System (INIS)

    Linn, Nicholas C; Sun, C-H; Arya, Ajay; Jiang Peng; Jiang Bin

    2009-01-01

    This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10 8 ). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

  2. Stochastic Capsule Endoscopy Image Enhancement

    Directory of Open Access Journals (Sweden)

    Ahmed Mohammed

    2018-06-01

    Full Text Available Capsule endoscopy, which uses a wireless camera to take images of the digestive tract, is emerging as an alternative to traditional colonoscopy. The diagnostic values of these images depend on the quality of revealed underlying tissue surfaces. In this paper, we consider the problem of enhancing the visibility of detail and shadowed tissue surfaces for capsule endoscopy images. Using concentric circles at each pixel for random walks combined with stochastic sampling, the proposed method enhances the details of vessel and tissue surfaces. The framework decomposes the image into two detailed layers that contain shadowed tissue surfaces and detail features. The target pixel value is recalculated for the smooth layer using similarity of the target pixel to neighboring pixels by weighting against the total gradient variation and intensity differences. In order to evaluate the diagnostic image quality of the proposed method, we used clinical subjective evaluation with a rank order on selected KID image database and compared it to state-of-the-art enhancement methods. The result showed that the proposed method provides a better result in terms of diagnostic image quality and objective quality contrast metrics and structural similarity index.

  3. Theory of hyperbolic stratified nanostructures for surface-enhanced Raman scattering

    Science.gov (United States)

    Wong, Herman M. K.; Dezfouli, Mohsen Kamandar; Axelrod, Simon; Hughes, Stephen; Helmy, Amr S.

    2017-11-01

    We theoretically investigate the enhancement of surface enhanced Raman spectroscopy (SERS) using hyperbolic stratified nanostructures and compare to metal nanoresonators. The photon Green function of each nanostructure within its environment is first obtained from a semianalytical modal theory, which is used in a quantum optics formalism of the molecule-nanostructure interaction to model the SERS spectrum. An intuitive methodology is presented for calculating the single-molecule enhancement factor (SMEF), which is also able to predict known experimental SERS enhancement factors of a gold nanodimer. We elucidate the important figures-of-merit of the enhancement and explore these for different designs. We find that the use of hyperbolic stratified materials can enhance the photonic local density of states (LDOS) by close to two times in comparison to pure metal nanostructures, when both designed to work at the same operating wavelengths. However, the increased LDOS is accompanied by higher electric field concentration within the lossy hyperbolic material, which leads to increased quenching that serves to reduce the overall detected SERS enhancement in the far field. For nanoresonators with resonant localized surface plasmon wavelengths in the near-infrared, the SMEF for the hyperbolic stratified nanostructure is approximately one order of magnitude lower than the pure metal counterpart. Conversely, we show that by detecting the Raman signal using a near-field probe, hyperbolic materials can provide an improvement in SERS enhancement compared to using pure metal nanostructures when the probe is sufficiently close (<50 nm ) to the Raman active molecule at the plasmonic hotspot.

  4. Surface-enhanced Raman scattering reveals adsorption of mitoxantrone on plasma membrane of living cells

    International Nuclear Information System (INIS)

    Breuzard, G.; Angiboust, J.-F.; Jeannesson, P.; Manfait, M.; Millot, J.-M.

    2004-01-01

    Surface-enhanced Raman scattering (SERS) spectroscopy was applied to analyze mitoxantrone (MTX) adsorption on the plasma membrane microenvironment of sensitive (HCT-116 S) or BCRP/MXR-type resistant (HCT-116 R) cells. The addition of silver colloid to MTX-treated cells revealed an enhanced Raman scattering of MTX. Addition of extracellular DNA induced a total extinction of MTX Raman intensity for both cell lines, which revealed an adsorption of MTX on plasma membrane. A threefold higher MTX Raman intensity was observed for HCT-116 R, suggesting a tight MTX adsorption in the plasma membrane microenvironment. Fluorescence confocal microscopy confirmed a relative MTX emission around plasma membrane for HCT-116 R. After 30 min at 4 deg. C, a threefold decrease of the MTX Raman scattering was observed for HCT-116 R, contrary to HCT-116 S. Permeation with benzyl alcohol revealed a threefold decrease of membrane MTX adsorption on HCT-116 R, exclusively. This additional MTX adsorption should correspond to the drug bound to an unstable site on the HCT-116 R membrane. This study showed that SERS spectroscopy could be a direct method to reveal drug adsorption to the membrane environment of living cells

  5. Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene

    Science.gov (United States)

    Eliel, G. S. N.; Ribeiro, H. B.; Sato, K.; Saito, R.; Lu, Chun-Chieh; Chiu, Po-Wen; Fantini, C.; Righi, A.; Pimenta, M. A.

    2017-12-01

    A resonant Raman study of twisted bilayer graphene (TBG) samples with different twisting angles using many different laser lines in the visible range is presented. The samples were fabricated by CVD technique and transferred to Si/SiO2 substrates. The Raman excitation profiles of the huge enhancement of the G-band intensity for a group of different TBG flakes were obtained experimentally, and the analysis of the profiles using a theoretical expression for the Raman intensities allowed us to obtain the energies of the van Hove singularities generated by the Moiré patterns and the lifetimes of the excited state of the Raman process. Our results exhibit a good agreement between experimental and calculated energies for van Hove singularities and show that the lifetime of photoexcited carrier does not depend significantly on the twisting angle in the range intermediate angles ( 𝜃 between 10∘ and 15∘). We observed that the width of the resonance window (Γ ≈ 250 meV) is much larger than the REP of the Raman modes of carbon nanotubes, which are also enhanced by resonances with van Hove singularities.

  6. High-speed vibrational imaging and spectral analysis of lipid bodies by compound Raman microscopy.

    Science.gov (United States)

    Slipchenko, Mikhail N; Le, Thuc T; Chen, Hongtao; Cheng, Ji-Xin

    2009-05-28

    Cells store excess energy in the form of cytoplasmic lipid droplets. At present, it is unclear how different types of fatty acids contribute to the formation of lipid droplets. We describe a compound Raman microscope capable of both high-speed chemical imaging and quantitative spectral analysis on the same platform. We used a picosecond laser source to perform coherent Raman scattering imaging of a biological sample and confocal Raman spectral analysis at points of interest. The potential of the compound Raman microscope was evaluated on lipid bodies of cultured cells and live animals. Our data indicate that the in vivo fat contains much more unsaturated fatty acids (FAs) than the fat formed via de novo synthesis in 3T3-L1 cells. Furthermore, in vivo analysis of subcutaneous adipocytes and glands revealed a dramatic difference not only in the unsaturation level but also in the thermodynamic state of FAs inside their lipid bodies. Additionally, the compound Raman microscope allows tracking of the cellular uptake of a specific fatty acid and its abundance in nascent cytoplasmic lipid droplets. The high-speed vibrational imaging and spectral analysis capability renders compound Raman microscopy an indispensible analytical tool for the study of lipid-droplet biology.

  7. Mathematical model for biomolecular quantification using large-area surface-enhanced Raman spectroscopy mapping

    DEFF Research Database (Denmark)

    Palla, Mirkó; Bosco, Filippo; Yang, Jaeyoung

    2015-01-01

    Surface-enhanced Raman spectroscopy (SERS) based on nanostructured platforms is a promising technique for quantitative and highly sensitive detection of biomolecules in the field of analytical biochemistry. Here, we report a mathematical model to predict experimental SERS signal (or hotspot) inte...

  8. Applicability of surface-enhanced resonance Raman scattering for the direct discrimination of ballpoint pen inks

    NARCIS (Netherlands)

    Seifar, R.M.; Verheul, J.M.; Ariese, F.; Brinkman, U.A.T.; Gooijer, C.

    2001-01-01

    In situ surface-enhanced resonance Raman spectroscopy (SERRS) with excitation at 685 nm is suitable for the direct discrimination of blue and black ballpoint pen inks on paper. For black inks, shorter excitation wavelengths can also be used. For blue inks, SERRS at 514.5 and 457.9 nm does not

  9. Extending the plasmonic lifetime of tip-enhanced Raman spectroscopy probes

    NARCIS (Netherlands)

    Kumar, Naresh; Spencer, Steve J; Imbraguglio, Dario; Rossi, Andrea M; Wain, Andrew J; Weckhuysen, Bert M; Roy, Debdulal

    2016-01-01

    Tip-enhanced Raman spectroscopy (TERS) is an emerging technique for simultaneous mapping of chemical composition and topography of a surface at the nanoscale. However, rapid degradation of TERS probes, especially those coated with silver, is a major bottleneck to the widespread uptake of this

  10. Mathematical model for biomolecular quantification using surface-enhanced Raman spectroscopy based signal intensity distributions

    DEFF Research Database (Denmark)

    Palla, Mirko; Bosco, Filippo Giacomo; Yang, Jaeyoung

    2015-01-01

    This paper presents the development of a novel statistical method for quantifying trace amounts of biomolecules by surface-enhanced Raman spectroscopy (SERS) using a rigorous, single molecule (SM) theory based mathematical derivation. Our quantification framework could be generalized for planar...

  11. Ag coated microneedle based surface enhanced Raman scattering probe for intradermal measurements

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2013-06-01

    We propose a silver coated microneedle to detect test molecules, including R6G and glucose, positioned at a depth of more than 700 μm below a skin phantom surface for mimicking intradermal surface-enhanced Raman scattering measurements.

  12. Raman excitation profiles of hybrid systems constituted by single-layer graphene and free base phthalocyanine: Manifestations of two mechanisms of graphene-enhanced Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Uhlířová, T.; Mojzeš, P.; Melníková Komínková, Zuzana; Kalbáč, Martin; Sutrová, Veronika; Šloufová, I.; Vlčková, B.

    2017-01-01

    Roč. 48, č. 10 (2017), s. 1270-1281 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : graphene-enhanced Raman scattering * single-layer graphene * free base phthalocyanine * Raman excitation profiles * photoinduced charge transfer Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 2.969, year: 2016

  13. Label-free cellular imaging by broadband coherent anti-Stokes Raman scattering microscopy.

    Science.gov (United States)

    Parekh, Sapun H; Lee, Young Jong; Aamer, Khaled A; Cicerone, Marcus T

    2010-10-20

    Raman microspectroscopy can provide the chemical contrast needed to characterize the complex intracellular environment and macromolecular organization in cells without exogenous labels. It has shown a remarkable ability to detect chemical changes underlying cell differentiation and pathology-related chemical changes in tissues but has not been widely adopted for imaging, largely due to low signal levels. Broadband coherent anti-Stokes Raman scattering (B-CARS) offers the same inherent chemical contrast as spontaneous Raman but with increased acquisition rates. To date, however, only spectrally resolved signals from the strong CH-related vibrations have been used for CARS imaging. Here, we obtain Raman spectral images of single cells with a spectral range of 600-3200 cm⁻¹, including signatures from weakly scattering modes as well as CH vibrations. We also show that B-CARS imaging can be used to measure spectral signatures of individual cells at least fivefold faster than spontaneous Raman microspectroscopy and can be used to generate maps of biochemical species in cells. This improved spectral range and signal intensity opens the door for more widespread use of vibrational spectroscopic imaging in biology and clinical diagnostics. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Label-free imaging of mammalian cell nucleoli by Raman microspectroscopy.

    Science.gov (United States)

    Schulze, H Georg; Konorov, Stanislav O; Piret, James M; Blades, Michael W; Turner, Robin F B

    2013-06-21

    The nucleolus is a prominent subnuclear structure whose major function is the transcription and assembly of ribosome subunits. The size of the nucleolus varies with the cell cycle, proliferation rate and stress. Changes in nucleolar size, number, chemical composition, and shape can be used to characterize malignant cells. We used spontaneous Raman microscopy as a label-free technique to examine nucleolar spatial and chemical features. Raman images of the 1003 cm(-1) phenylalanine band revealed large, well-defined subnuclear protein structures in MFC-7 breast cancer cells. The 783 cm(-1) images showed that nucleic acids were similarly distributed, but varied more in intensity, forming observable high-intensity regions. High subnuclear RNA concentrations were observed within some of these regions as shown by 809 cm(-1) Raman band images. Principal component analyses of sub-images and library spectra validated the subnuclear presence of RNA. They also revealed that an actin-like protein covaried with DNA within the nucleolus, a combination that accounted for 64% or more of the spectral variance. Embryonic stem cells are another rapidly proliferating cell type, but their nucleoli were not as large or well defined. Estimating the size of the larger MCF-7 nucleolus was used to show the utility of Raman microscopy for morphometric analyses. It was concluded that imaging based on Raman microscopy provides a promising new method for the study of nucleolar function and organization, in the evaluation of drug and experimental effects on the nucleolus, and in clinical diagnostics and prognostics.

  15. Raman hyperspectral imaging and analysis of fat spreads

    NARCIS (Netherlands)

    Dalen, van G.; Velzen, van E.J.J.; Heussen, P.C.M.; Sovago, M.; Malssen, van K.F.; Duynhoven, van J.P.M.

    2017-01-01

    The microstructure of fat spreads is of fundamental importance to their sensorial properties such as texture, mouthfeel and spreadability. Fat spreads are water in oil emulsions,with a continuous phase supported by a fat crystal network. Confocal Raman microscopy offers the possibility for the

  16. Combined Raman and continuous-wave-excited two-photon fluorescence cell imaging

    NARCIS (Netherlands)

    Uzunbajakava, N.; Otto, Cornelis

    2003-01-01

    We demonstrate a confocal optical microscope that combines cw two-photon-excited fluorescence microscopy with confocal Raman microscopy. With this microscope fast image acquisition with fluorescence imaging can be used to select areas of interest for subsequent chemical analysis with spontaneous

  17. Surface-enhanced Raman scattering from graphene covered gold nanocap arrays

    Science.gov (United States)

    Long, Kailin; Luo, Xiaoguang; Nan, Haiyan; Du, Deyang; Zhao, Weiwei; Ni, Zhenhua; Qiu, Teng

    2013-11-01

    This work reports an efficient method to fabricate large-area flexible substrates for surface enhanced Raman scattering (SERS) application. Our technique is based on a single-step direct imprint process via porous anodic alumina stamps. Periodic hexagonal arrangements of porous anodic alumina stamps are transferred to the polyethylene terephthalate substrates by mechanically printing process. Printed nanocaps will turn into "hot spots" for electromagnetic enhancement with a deposited gold film by high vacuum evaporation. The gaps between the nanocaps are controllable with a tight correspondence to the thickness of the deposited gold, which dramatically influence the enhancement factor. After covered with a single-layer graphene sheet, the gold nanocap substrate can be further optimized with an extra enhancement of Raman signals, and it is available for the trace detection of probe molecules. This convenient, simple, and low-cost method of making flexible SERS-active substrates potentially opens a way towards biochemical analysis and disease detection.

  18. Surface-enhanced Raman scattering from metal and transition metal nano-caped arrays

    Science.gov (United States)

    Sun, Huanhuan; Gao, Renxian; Zhu, Aonan; Hua, Zhong; Chen, Lei; Wang, Yaxin; Zhang, Yongjun

    2018-03-01

    The metal and transition metal cap-shaped arrays on polystyrene colloidal particle (PSCP) templates were fabricated to study the surface-enhanced Raman scattering (SERS) effect. We obtained the Ag and Fe complex film by a co-sputtering deposition method. The size of the deposited Fe particle was changed by the sputtering power. We also study the SERS enhancement mechanism by decorating the PATP probe molecule on the different films. The SERS signals increased firstly, and then decreased as the size of Fe particles grows gradually. The finite-difference time domain (FDTD) simulation and experimental Raman results manifest that SERS enhancement was mainly attributed to surface plasma resonance (SPR) between Ag and Ag nanoparticles. The SERS signals of PATP molecule were enhanced to reach a lowest detectable concentration of 10-8 mol/L. The research demonstrates that the SERS substrates with Ag-Fe cap-shaped arrays have a high sensitivity.

  19. Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sarycheva, Asia [Drexel Univ., Philadelphia, PA (United States); Makaryan, Taron [Drexel Univ., Philadelphia, PA (United States); Maleski, Kathleen [Drexel Univ., Philadelphia, PA (United States); Satheeshkumar, Elumalai [National Cheng Kung Univ., Tainan (Taiwan); National Institute of Technology-Trichy, Tamil Nadu (India); Melikyan, Armen [Russian-Armenian (Slavonic) State Univ., Yerevan (Armenia); Minassian, Hayk [A. Alikhanian National Science Lab., Yerevan (Armenia); Yoshimura, Masahiro [National Cheng Kung Univ., Tainan (Taiwan); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

    2017-08-22

    Here, noble metal (gold or silver) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic conductivity and plasmon resonance in the visible or near-infrared range, making them promising candidates for a wide variety of applications. Herein, we show that 2D titanium carbide, Ti3C2Tx, enhances Raman signal from organic dyes on a substrate and in solution. As a proof of concept, MXene SERS substrates were manufactured by spray-coating and used to detect several common dyes, with calculated enhancement factors reaching ~106. Titanium carbide MXene demonstrates SERS effect in aqueous colloidal solutions, suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance positively charged molecules.

  20. Phase dispersion of Raman and Rayleigh-enhanced four-wave mixings in femtosecond polarization beats

    International Nuclear Information System (INIS)

    Yan, Zhao; Zhi-Qiang, Nie; Chang-Biao, Li; Yan-Peng, Zhang; Chen-Li, Gan; Huai-Bin, Zheng; Yuan-Yuan, Li; Ke-Qing, Lu

    2009-01-01

    Based on color-locking noisy field correlation in three Markovian stochastic models, phase dispersions of the Raman- and Rayleigh-enhanced four-wave mixing (FWM) have been investigated. The phase dispersions are modified by both linewidth and time delay for negative time delay, but only by linewidth for positive time delay. Moreover, the results under narrowband condition are close to the nonmodified nonlinear dispersion and absorption of the material. Homodyne and heterodyne detections of the Raman, the Rayleigh and the mixing femtosecond difference-frequency polarization beats have also been investigated, separately

  1. Fiber-optic surface-enhanced Raman system for field screening of hazardous compounds

    International Nuclear Information System (INIS)

    Ferrell, T.L.; Goudonnet, J.P.; Arakawa, E.T.; Reddick, R.C.; Gammage, R.B.; Haas, J.W.; James, D.R.; Wachter, E.A.

    1988-01-01

    Surface-enhanced Raman scattering permits identification of compounds adsorbed onto a metal microbase that is microlithographically produced with submicron resolution. Less than one percent of a monolayer of a Raman Active target compound offers a high signal-to-noise ratio. By depositing the microbase on the exterior of a fiber optic cable, convenient field screening or monitoring is permitted. By using highly effective microbases, it is possible to reduce laser power requirements sufficiently to allow an economical, but complete, system to be housed in a suitcase. We shall present details of SERS system of this type and shall show data on samples of interest in the screening of hazardous compounds

  2. Surface-enhanced Raman scattering on molecular self-assembly in nanoparticle-hydrogel composite.

    Science.gov (United States)

    Miljanić, Snezana; Frkanec, Leo; Biljan, Tomislav; Meić, Zlatko; Zinić, Mladen

    2006-10-24

    Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups.

  3. Visible wavelength surface-enhanced Raman spectroscopy from In-InP nanopillars for biomolecule detection

    Science.gov (United States)

    Murdoch, B. J.; Portoles, J. F.; Tardio, S.; Barlow, A. J.; Fletcher, I. W.; Cumpson, P. J.

    2016-12-01

    Visible wavelength surface-enhanced Raman spectroscopy (SERS) has been observed from bovine serum albumin (BSA) using In-InP nanopillars synthesised by Ar gas cluster ion beam sputtering of InP wafers. InP provides a high local refractive index for plasmonic In structures, which increases the wavelength of the In surface plasmon resonance. The Raman scattering signal was determined to be up to 285 times higher for BSA deposited onto In-InP nanopillars when compared with Si wafer substrates. These substrates demonstrate the label-free detection of biomolecules by visible wavelength SERS, without the use of noble metal particles.

  4. Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

    DEFF Research Database (Denmark)

    Palanco, Marta Espina; Mogensen, Klaus Bo; Guehlke, Marina

    2016-01-01

    We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial...... for one-and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic...... building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts....

  5. Image analysis enhancement and interpretation

    International Nuclear Information System (INIS)

    Glauert, A.M.

    1978-01-01

    The necessary practical and mathematical background are provided for the analysis of an electron microscope image in order to extract the maximum amount of structural information. Instrumental methods of image enhancement are described, including the use of the energy-selecting electron microscope and the scanning transmission electron microscope. The problems of image interpretation are considered with particular reference to the limitations imposed by radiation damage and specimen thickness. A brief survey is given of the methods for producing a three-dimensional structure from a series of two-dimensional projections, although emphasis is really given on the analysis, processing and interpretation of the two-dimensional projection of a structure. (Auth.)

  6. Magnetic Fe{sub 3}O{sub 4}-Au core-shell nanostructures for surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.A.; Adams, S.A.; Zhang, J.Z. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Lopez-Luke, T. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Cento de Investigaciones en Optica, A.P. 1-948 Leon, Gto. 37150 (Mexico); Torres-Castro, A. [Universidad Autonoma de Nuevo Leon, A.P. 126-F, Monterrey, NL, 66450 (Mexico)

    2012-11-15

    The synthesis, structural and optical characterization, and application of superparamagnetic and water-dispersed Fe{sub 3}O{sub 4}-Au core-shell nanoparticles for surface enhanced Raman scattering (SERS) is reported. The structure of the nanoparticles was determined by scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). STEM images of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles reveal an average diameter of 120 nm and a high degree of surface roughness. The nanoparticles, which display superparamagnetic properties due to the core Fe{sub 3}O{sub 4} material, exhibit a visible surface plasmon resonance (SPR) peaked at 580 nm due to the outer gold shell. The nanoparticles are used as a substrate for surface enhanced Raman scattering (SERS) with rhodamine 6G (R6G) as a Raman reporter molecule. The SERS enhancement factor is estimated to be on the order of 10{sup 6}, which is {proportional_to} 2 times larger than that of conventional gold nanoparticles (AuNPs) under similar conditions. Significantly, magnetically-induced aggregation of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles substantially enhanced SERS activity compared to non-magnetically-aggregated Fe{sub 3}O{sub 4}-Au nanoparticles. This is attributed to both increased scattering from the aggregates as well as ''hot spots'' due to more junction sites in the magnetically-induced aggregates. The magnetic properties of the Fe{sub 3}O{sub 4} core, coupled with the optical properties of the Au shell, make the Fe{sub 3}O{sub 4}-Au nanoparticles unique for various potential applications including biological sensing and therapy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Boron nitride nanosheets as improved and reusable substrates for gold nanoparticles enabled surface enhanced Raman spectroscopy

    KAUST Repository

    Cai, Qiran

    2015-01-01

    Atomically thin boron nitride (BN) nanosheets have been found to be excellent substrates for noble metal particles enabled surface enhanced Raman spectroscopy (SERS), thanks to their good adsorption of aromatic molecules, high thermal stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been synthesized on BN nanosheets using a simple but controllable and reproducible sputtering and annealing method. The size and density of the Au particles can be controlled by sputtering time, current and annealing temperature etc. Under the same sputtering and annealing conditions, the Au particles on BN of different thicknesses show various sizes because the surface diffusion coefficients of Au depend on the thickness of BN. Intriguingly, decorated with similar morphology and distribution of Au particles, BN nanosheets exhibit better Raman enhancements than silicon substrates as well as bulk BN crystals. Additionally, BN nanosheets show no noticeable SERS signal and hence cause no interference to the Raman signal of the analyte. The Au/BN substrates can be reused by heating in air to remove the adsorbed analyte without loss of SERS enhancement. This journal is © the Owner Societies 2015.

  8. Probing Xylan-Specific Raman Bands for Label-Free Imaging Xylan in Plant Cell Wall

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Yining; Yarbrough, John M.; Mittal, Ashutosh; Tucker, Melvin P.; Vinzant, Todd; Himmel, Michael E.

    2015-06-15

    Xylan constitutes a significant portion of biomass (e.g. 22% in corn stover used in this study). Xylan is also an important source of carbohydrates, besides cellulose, for renewable and sustainable energy applications. Currently used method for the localization of xylan in biomass is to use fluorescence confocal microscope to image the fluorescent dye labeled monoclonal antibody that specifically binds to xylan. With the rapid adoption of the Raman-based label-free chemical imaging techniques in biology, identifying Raman bands that are unique to xylan would be critical for the implementation of the above label-free techniques for in situ xylan imaging. Unlike lignin and cellulose that have long be assigned fingerprint Raman bands, specific Raman bands for xylan remain unclear. The major challenge is the cellulose in plant cell wall, which has chemical units highly similar to that of xylan. Here we report using xylanase to specifically remove xylan from feedstock. Under various degree of xylan removal, with minimum impact to other major cell wall components, i.e. lignin and cellulose, we have identified Raman bands that could be further tested for chemical imaging of xylan in biomass in situ.

  9. Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vincenz Sandfort

    2017-11-01

    Full Text Available The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF, namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm−1, which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures.

  10. Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Sandfort, Vincenz; Trabold, Barbara M; Abdolvand, Amir; Bolwien, Carsten; Russell, Philip St. J; Wöllenstein, Jürgen; Palzer, Stefan

    2017-11-24

    The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF), namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm -1 , which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures.

  11. Electromagnetic Modelling of Raman Enhancement from Nanoscale Structures as a Means to Predict the Efficacy of SERS Substrates

    Directory of Open Access Journals (Sweden)

    Richard J. C. Brown

    2007-01-01

    Full Text Available The requirement to optimise the balance between signal enhancement and reproducibility in surface enhanced Raman spectroscopy (SERS is stimulating the development of novel substrates for enhancing Raman signals. This paper describes the application of finite element electromagnetic modelling to predict the Raman enhancement produced from a variety of SERS substrates with differently sized, spaced and shaped morphologies with nanometre dimensions. For the first time, a theoretical comparison between four major generic types of SERS substrate (including metal nanoparticles, structured surfaces, and sharp tips has been performed and the results are presented and discussed. The results of the modelling are consistent with published experimental data from similar substrates.

  12. Surface-enhanced Raman scattering based nonfluorescent probe for multiplex DNA detection.

    Science.gov (United States)

    Sun, Lan; Yu, Chenxu; Irudayaraj, Joseph

    2007-06-01

    To provide rapid and accurate detection of DNA markers in a straightforward, inexpensive, and multiplex format, an alternative surface-enhanced Raman scattering based probe was designed and fabricated to covalently attach both DNA probing sequence and nonfluorescent Raman tags to the surface of gold nanoparticles (DNA-AuP-RTag). The intensity of Raman signal of the probes could be controlled through the surface coverage of the nonfluorescent Raman tags (RTags). Detection sensitivity of these probes could be optimized by fine-tuning the amount of DNA molecules and RTags on the probes. Long-term stability of the DNA-AuP-RTag probes was found to be good (over 3 months). Excellent multiplexing capability of the DNA-AuP-RTag scheme was demonstrated by simultaneous identification of up to eight probes in a mixture. Detection of hybridization of single-stranded DNA to its complementary targets was successfully accomplished with a long-term goal to use nonfluorescent RTags in a Raman-based DNA microarray platform.

  13. Surface-enhanced Raman spectroscopic monitor of triglyceride hydrolysis in a skin pore phantom

    Science.gov (United States)

    Weldon, Millicent K.; Morris, Michael D.

    1999-04-01

    Bacterial hydrolysis of triglycerides is followed in a sebum probe phantom by microprobe surface-enhanced Raman scattering (SERS) spectroscopy. The phantom consists of a purpose-built syringe pump operating at physiological flow rates connected to a 300 micron i.d. capillary. We employ silicon substrate SERS microprobes to monitor the hydrolysis products. The silicon support allows some tip flexibility that makes these probes ideal for insertion into small structures. Propionibacterium acnes are immobilized on the inner surface of the capillary. These bacteria hydrolyze the triglycerides in a model sebum emulsion flowing through the capillary. The transformation is followed in vitro as changes in the SERS caused by hydrolysis of triglyceride to fatty acid. The breakdown products consists of a mixture of mono- and diglycerides and their parent long chain fatty acids. The fatty acids adsorb as their carboxylates and can be readily identified by their characteristic spectra. The technique can also confirm the presence of bacteria by detection of short chain carboxylic acids released as products of glucose fermentation during the growth cycle of these cells. Co-adsorption of propionate is observed. Spatial localization of the bacteria is obtained by ex-situ line imaging of the probe.

  14. Surface-Enhanced Raman Scattering of Bacteria in Micro wells Constructed from Silver Nanoparticles

    International Nuclear Information System (INIS)

    Culha, M.; Yazici, M.M.; Kahraman, M.; Sahin, F.; Sesin Kocagoz, S.

    2012-01-01

    Whole bacterial cell characterization is critically important for fast bacterial identification. Surface-enhanced Raman scattering (SERS) is proven to be powerful technique to serve such a goal. In this study, the characterization of whole bacterial cells in the micro wells constructed from colloidal silver nanoparticles (AgNPs) with convective-assembly method is reported.- The proper size of the micro wells for the model bacteria, Escherichia coli and Staphylococcus cohnii, is determined to be 1.2μm from their electron microscopy images. A minimum dilution factor of 20 is necessary for the bacterial samples collected from growth media to diminish the bacterial aggregation to place the bacterial cells into the micro wells. The constructed micro well structures are tested for their bacterial SERS performance and compared to the SERS spectra obtained from the samples prepared with a simple mixing of bacteria and AgNPs for the same bacteria. The results indicate that micro well structures not only improve the spectral quality but also increase the reproducibility of the SERS spectra.

  15. Organelle-targeting surface-enhanced Raman scattering (SERS) nanosensors for subcellular pH sensing.

    Science.gov (United States)

    Shen, Yanting; Liang, Lijia; Zhang, Shuqin; Huang, Dianshuai; Zhang, Jing; Xu, Shuping; Liang, Chongyang; Xu, Weiqing

    2018-01-25

    The pH value of subcellular organelles in living cells is a significant parameter in the physiological activities of cells. Its abnormal fluctuations are commonly believed to be associated with cancers and other diseases. Herein, a series of surface-enhanced Raman scattering (SERS) nanosensors with high sensitivity and targeting function was prepared for the quantification and monitoring of pH values in mitochondria, nucleus, and lysosome. The nanosensors were composed of gold nanorods (AuNRs) functionalized with a pH-responsive molecule (4-mercaptopyridine, MPy) and peptides that could specifically deliver the AuNRs to the targeting subcellular organelles. The localization of our prepared nanoprobes in specific organelles was confirmed by super-high resolution fluorescence imaging and bio-transmission electron microscopy (TEM) methods. By the targeting ability, the pH values of the specific organelles can be determined by monitoring the vibrational spectral changes of MPy with different pH values. Compared to the cases of reported lysosome and cytoplasm SERS pH sensors, more accurate pH values of mitochondria and nucleus, which could be two additional intracellular tracers for subcellular microenvironments, were disclosed by this SERS approach, further improving the accuracy of discrimination of related diseases. Our sensitive SERS strategy can also be employed to explore crucial physiological and biological processes that are related to subcellular pH fluctuations.

  16. Surface-Enhanced Raman Scattering of Bacteria in Microwells Constructed from Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mustafa Çulha

    2012-01-01

    Full Text Available Whole bacterial cell characterization is critically important for fast bacterial identification. Surface-enhanced Raman scattering (SERS is proven to be powerful technique to serve such a goal. In this study, the characterization of whole bacterial cells in the microwells constructed from colloidal silver nanoparticles (AgNPs with “convective-assembly” method is reported. The proper size of the microwells for the model bacteria, Escherichia coli and Staphylococcus cohnii, is determined to be 1.2 μm from their electron microscopy images. A minimum dilution factor of 20 is necessary for the bacterial samples collected from growth media to diminish the bacterial aggregation to place the bacterial cells into the microwells. The constructed microwell structures are tested for their bacterial SERS performance and compared to the SERS spectra obtained from the samples prepared with a simple mixing of bacteria and AgNPs for the same bacteria. The results indicate that microwell structures not only improve the spectral quality but also increase the reproducibility of the SERS spectra.

  17. Microwave assisted in situ synthesis of Ag–NaCMC films and their reproducible surface-enhanced Raman scattering signals

    International Nuclear Information System (INIS)

    Jiang, Tao; Li, Junpeng; Zhang, Li; Wang, Binbing; Zhou, Jun

    2014-01-01

    Graphical abstract: Two kinds of Ag–NaCMC films for surface-enhanced Raman scattering (SERS) were prepared by conventional heating and microwave assisted in situ reduction methods without any additional capping or reducing agents. A relatively narrow and symmetric surface plasmon resonance band was observed in the absorption spectra of the films fabricated by the microwave assisted in situ reduction method. More uniform silver nanoparticles (NPs) implied by the symmetric absorption spectrum were further confirmed by the scanning electron microscopy images. After the simulation of the E-field intensity distribution around the silver NPs in NaCMC film, the Raman scattering enhancement factors (EFs) of these films were then investigated with 4-mercaptobenzoic acid molecule as a SERS reporter. Improved reproducibility of SERS signal was obtained in the microwave assisted synthesized Ag–NaCMC film, although it maintained an EF as only 1.11 × 10 8 . The reproducible SERS signal of the Ag–NaCMC film is particularly attractive and this microwave assisted in situ reduction method is suitable for the production of excellent substrate for biosensor application. - Highlights: • The synthesis of Ag–NaCMC films was successfully fulfilled by a low-cost microwave method. • More uniform silver nanoparticles were observed in Ag–NaCMC film synthesized by microwave. • Improved reproducibility of SERS signal was obtained in microwave synthesized Ag–NaCMC film. - Abstract: Two kinds of Ag–NaCMC films for surface-enhanced Raman scattering (SERS) were prepared by conventional heating and microwave assisted in situ reduction methods without any additional capping or reducing agents. A relatively narrow and symmetric surface plasmon resonance band was observed in the absorption spectra of the films fabricated by the microwave assisted in situ reduction method. More uniform silver nanoparticles (NPs) implied by the symmetric absorption spectrum were further confirmed by

  18. Wide-Field Vibrational Phase Contrast Imaging Based on Coherent Anti-Stokes Raman Scattering Holography

    International Nuclear Information System (INIS)

    Lv Yong-Gang; Ji Zi-Heng; Dong Da-Shan; Gong Qi-Huang; Shi Ke-Bin

    2015-01-01

    We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering (CARS) microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging. (paper)

  19. Molecular cavity optomechanics as a theory of plasmon-enhanced Raman scattering.

    Science.gov (United States)

    Roelli, Philippe; Galland, Christophe; Piro, Nicolas; Kippenberg, Tobias J

    2016-02-01

    The exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon-molecule interaction. We thereby reveal an enhancement mechanism not considered before: dynamical backaction amplification of molecular vibrations. We first map the system onto the canonical Hamiltonian of cavity optomechanics, in which the molecular vibration and the plasmon are parametrically coupled. We express the vacuum optomechanical coupling rate for individual molecules in plasmonic 'hot-spots' in terms of the vibrational mode's Raman activity and find it to be orders of magnitude larger than for microfabricated optomechanical systems. Remarkably, the frequency of commonly studied molecular vibrations can be comparable to or larger than the plasmon's decay rate. Together, these considerations predict that an excitation laser blue-detuned from the plasmon resonance can parametrically amplify the molecular vibration, leading to a nonlinear enhancement of Raman emission that is not predicted by the conventional theory. Our optomechanical approach recovers known results, provides a quantitative framework for the calculation of cross-sections, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancements. It also provides a quantum mechanical framework to analyse plasmon-vibrational interactions in terms of molecular quantum optomechanics.

  20. Emerging technology: applications of Raman spectroscopy for prostate cancer.

    Science.gov (United States)

    Kast, Rachel E; Tucker, Stephanie C; Killian, Kevin; Trexler, Micaela; Honn, Kenneth V; Auner, Gregory W

    2014-09-01

    There is a need in prostate cancer diagnostics and research for a label-free imaging methodology that is nondestructive, rapid, objective, and uninfluenced by water. Raman spectroscopy provides a molecular signature, which can be scaled from micron-level regions of interest in cells to macroscopic areas of tissue. It can be used for applications ranging from in vivo or in vitro diagnostics to basic science laboratory testing. This work describes the fundamentals of Raman spectroscopy and complementary techniques including surface enhanced Raman scattering, resonance Raman spectroscopy, coherent anti-Stokes Raman spectroscopy, confocal Raman spectroscopy, stimulated Raman scattering, and spatially offset Raman spectroscopy. Clinical applications of Raman spectroscopy to prostate cancer will be discussed, including screening, biopsy, margin assessment, and monitoring of treatment efficacy. Laboratory applications including cell identification, culture monitoring, therapeutics development, and live imaging of cellular processes are discussed. Potential future avenues of research are described, with emphasis on multiplexing Raman spectroscopy with other modalities.

  1. Selective isolation and noninvasive analysis of circulating cancer stem cells through Raman imaging.

    Science.gov (United States)

    Cho, Hyeon-Yeol; Hossain, Md Khaled; Lee, Jin-Ho; Han, Jiyou; Lee, Hun Joo; Kim, Kyeong-Jun; Kim, Jong-Hoon; Lee, Ki-Bum; Choi, Jeong-Woo

    2018-04-15

    Circulating cancer stem cells (CCSCs), a rare circulating tumor cell (CTC) type, recently arose as a useful resource for monitoring and characterizing both cancers and their metastatic derivatives. However, due to the scarcity of CCSCs among hematologic cells in the blood and the complexity of the phenotype confirmation process, CCSC research can be extremely challenging. Hence, we report a nanoparticle-mediated Raman imaging method for CCSC characterization which profiles CCSCs based on their surface marker expression phenotypes. We have developed an integrated combinatorial Raman-Active Nanoprobe (RAN) system combined with a microfluidic chip to successfully process complete blood samples. CCSCs and CTCs were detected (90% efficiency) and classified in accordance with their respective surface marker expression via completely distinct Raman signals of RANs. Selectively isolated CCSCs (93% accuracy) were employed for both in vitro and in vivo tumor phenotyping to identify the tumorigenicity of the CCSCs. We utilized our new method to predict metastasis by screening blood samples from xenograft models, showing that upon CCSC detection, all subjects exhibited liver metastasis. Having highly efficient detection and noninvasive isolation capabilities, we have demonstrated that our RAN-based Raman imaging method will be valuable for predicting cancer metastasis and relapse via CCSC detection. Moreover, the exclusion of peak overlapping in CCSC analysis with our Raman imaging method will allow to expand the RAN families for various cancer types, therefore, increasing therapeutic efficacy by providing detailed molecular features of tumor subtypes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Glucose oxidase probe as a surface-enhanced Raman scattering sensor for glucose.

    Science.gov (United States)

    Qi, Guohua; Wang, Yi; Zhang, Biying; Sun, Dan; Fu, Cuicui; Xu, Weiqing; Xu, Shuping

    2016-10-01

    Glucose oxidase (GOx) possessing a Raman-active chromophore (flavin adenine dinucleotide) is used as a signal reporter for constructing a highly specific "turn off" surface-enhanced Raman scattering (SERS) sensor for glucose. This sensing chip is made by the electrostatic assembly of GOx over silver nanoparticle (Ag NP)-functionalized SERS substrate through a positively charged polyelectrolyte linker under the pH of 6.86. To trace glucose in blood serum, owing to the reduced pH value caused by the production of gluconic acid in the GOx-catalyzed oxidation reaction, the bonding force between GOx and polyelectrolyte weakens, making GOx drop off from the sensing chip. As a result, the SERS intensity of GOx on the chip decreases along with the concentration of glucose. This glucose SERS sensor exhibits excellent selectivity based on the specific GOx/glucose catalysis reaction and high sensitivity to 1.0 μM. The linear sensing range is 2.0-14.0 mM, which also meets the requirement on the working range of the human blood glucose detection. Using GOx as a probe shows superiority over other organic probes because GOx almost has no toxicity to the biological system. This sensing mechanism can be applied for intracellular in vivo SERS monitoring of glucose in the future. Graphical abstract Glucose oxidase is used as a Raman signal reporter for constructing a highly specific glucose surface-enhanced Raman scattering (SERS) sensor.

  3. Surface enhanced Raman spectroscopy platform based on graphene with one-year stability

    Energy Technology Data Exchange (ETDEWEB)

    Tite, Teddy [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France); Barnier, Vincent [Ecole Nationale Supérieure des Mines, CNRS, Laboratoire Georges Friedel UMR 5307, 158 cours Fauriel, F-42023 Saint-Etienne (France); Donnet, Christophe, E-mail: Christophe.Donnet@univ-st-etienne.fr [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France); Loir, Anne–Sophie; Reynaud, Stéphanie; Michalon, Jean–Yves; Vocanson, Francis; Garrelie, Florence [Univ Lyon, UJM-Saint-Etienne, CNRS, Laboratoire Hubert Curien UMR 5516, 18 rue Professeur Benoit Lauras, F-42000 Saint-Etienne (France)

    2016-04-01

    We report the synthesis, characterization and use of a robust surface enhanced Raman spectroscopy platform with a stable detection for up to one year of Rhodamine R6G at a concentration of 10{sup −6} M. The detection of aminothiophenol and methyl parathion, as active molecules of commercial insecticides, is further demonstrated at concentrations down to 10{sup −5}–10{sup −6} M. This platform is based on large scale textured few-layer (fl) graphene obtained without any need of graphene transfer. The synthesis route is based on diamond-like carbon films grown by pulsed laser deposition, deposited onto silicon substrates covered by a Ni layer prior to diamond-like carbon deposition. The formation of fl-graphene film, confirmed by Raman spectroscopy and mapping, is obtained by thermal annealing inducing the diffusion of Ni atoms and the concomitant formation of nickel silicide compounds, as identified by Raman and Auger electron spectroscopies. The textured fl-graphene films were decorated with gold nanoparticles to optimize the efficiency of the SERS device to detect organic molecules at low concentrations. - Highlights: • Synthesis of graphene film from amorphous carbon by pulsed laser deposition with nickel catalyst • Large scale textured graphene with nanoscale roughness obtained through nickel silicide formation • Films used for surface enhanced Raman spectroscopy detection of organophosphate compounds • Stability of the SERS platforms over up to one year.

  4. A pH dependent Raman and surface enhanced Raman spectroscopic studies of citrazinic acid aided by theoretical calculations

    Science.gov (United States)

    Sarkar, Sougata; Chowdhury, Joydeep; Dutta, Soumen; Pal, Tarasankar

    2016-12-01

    A pH dependent normal Raman scattering (NRS) and surface enhanced Raman scattering (SERS) spectral patterns of citrazinic acid (CZA), a biologically important molecule, have been investigated. The acid, with different pKa values ( 4 and 11) for the two different functional groups (-COOH and -OH groups), shows interesting range of color changes (yellow at pH 14 and brown at pH 2) with the variation in solution pH. Thus, depending upon the pH of the medium, CZA molecule can exist in various protonated and/or deprotonated forms. Here we have prescribed the existence different possible forms of CZA at different pH (Forms ;C;, ;H; and ;Dprot; at pH 14 and Forms ;A;, ;D;, and ;P; at pH 2 respectively). The NRS spectra of these solutions and their respective SERS spectra over gold nanoparticles were recorded. The spectra clearly differ in their spectral profiles. For example the SERS spectra recorded with the CZA solution at pH 2 shows blue shift for different bands compared to its NRS window e.g. 406 to 450 cm- 1, 616 to 632 cm- 1, 1332 to 1343 cm- 1 etc. Again, the most enhanced peak at 1548 cm- 1 in NRS while in the SERS window this appears at 1580 cm- 1. Similar observation was also made for CZA at pH 14. For example, the 423 cm- 1 band in the NRS profile experience a blue shift and appears at 447 cm- 1 in the SERS spectrum as well as other bands at 850, 1067 and 1214 cm- 1 in the SERS window are markedly enhanced. It is also worth noting that the SERS spectra at the different pH also differ from each other. These spectral differences indicate the existence of various adsorptive forms of the CZA molecule depending upon the pH of the solution. Therefore based on the experimental findings we propose different possible molecular forms of CZA at different pH (acidic and alkaline) conditions. For example forms 'A', 'D' and 'P' existing in acidic pH (pH 2) and three other deprotonated forms 'C', 'H' and 'Dprot' in alkaline pH (pH 14). The DFT calculations for these

  5. Raman-based imaging uncovers the effects of alginate hydrogel implants in spinal cord injury

    Science.gov (United States)

    Galli, Roberta; Tamosaityte, Sandra; Koch, Maria; Sitoci-Ficici, Kerim H.; Later, Robert; Uckermann, Ortrud; Beiermeister, Rudolf; Gelinsky, Michael; Schackert, Gabriele; Kirsch, Matthias; Koch, Edmund; Steiner, Gerald

    2015-07-01

    The treatment of spinal cord injury by using implants that provide a permissive environment for axonal growth is in the focus of the research for regenerative therapies. Here, Raman-based label-free techniques were applied for the characterization of morphochemical properties of surgically induced spinal cord injury in the rat that received an implant of soft unfunctionalized alginate hydrogel. Raman microspectroscopy followed by chemometrics allowed mapping the different degenerative areas, while multimodal multiphoton microscopy (e.g. the combination of coherent anti-Stokes Raman scattering (CARS), endogenous two-photon fluorescence and second harmonic generation on the same platform) enabled to address the morphochemistry of the tissue at cellular level. The regions of injury, characterized by demyelination and scarring, were retrieved and the distribution of key tissue components was evaluated by Raman mapping. The alginate hydrogel was detected in the lesion up to six months after implantation and had positive effects on the nervous tissue. For instance, multimodal multiphoton microscopy complemented the results of Raman mapping, providing the micromorphology of lipid-rich tissue structures by CARS and enabling to discern lipid-rich regions that contained myelinated axons from degenerative regions characterized by myelin fragmentation and presence of foam cells. These findings demonstrate that Raman-based imaging methods provide useful information for the evaluation of alginate implant effects and have therefore the potential to contribute to new strategies for monitoring degenerative and regenerative processes induced in SCI, thereby improving the effectiveness of therapies.

  6. Development of probes for bioanalytic applications of the surface-enhanced Raman scattering; Entwicklung neuer Sonden fuer bioanalytische Anwendungen der oberflaechenverstaerkten Raman-Streuung

    Energy Technology Data Exchange (ETDEWEB)

    Matschulat, Andrea Isabel

    2011-07-01

    Surface-enhanced Raman scattering (SERS) has been established as a versatile tool for probing and labeling in analytical applications, based on the vibrational spectra of samples as well as label molecules in the proximity of noble metal nanostructures. The aim of this work was the construction of novel SERS hybrid probes. The hybrid probes consisted of Au and Ag nanoparticles and reporter molecules, as well as a targeting unit. The concept for the SERS hybrid probe design was followed by experiments comprising characterization techniques such as UV/Vis-spectroscopy (UV/Vis), Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS), respectively. SERS experiments were performed for studying and optimizing the plasmonic properties of nanoparticles with respect to their enhancement capabilities. The SERS-probes had to meet following requirements: biocompatibility, stability in physiological media, and enhancement of Raman-signals from Raman reporter molecules enabling the identification of different probes even in a complex biological environment. Au and Ag nanoaggregates were found to be the most appropriate SERS substrates for the hybrid probe design. The utilization of Raman reporters enabled the identification of different SERS probes in multiplexing experiments. In particular, the multiplexing capability of ten various reporter molecules para-aminobenzenethiol, 2-naphthalenethiol, crystal violet, rhodamine (B) isothiocyanate, fluorescein isothiocyanate, 5,5'dithiobis(2-nitrobenzoic acid), para-mercaptobenzoic acid, acridine orange, safranine O und nile blue was studied using NIR-SERS excitation. As demonstrated by the results the reporters could be identified through their specific Raman signature even in the case of high structural similarity. Chemical separation analysis of the reporter signatures was performed in a trivariate approach, enabling the discrimination through an automated calculation of specific band ratios. The trivariate

  7. Segmentation of confocal Raman microspectroscopic imaging data using edge-preserving denoising and clustering.

    Science.gov (United States)

    Alexandrov, Theodore; Lasch, Peter

    2013-06-18

    Over the past decade, confocal Raman microspectroscopic (CRM) imaging has matured into a useful analytical tool to obtain spatially resolved chemical information on the molecular composition of biological samples and has found its way into histopathology, cytology, and microbiology. A CRM imaging data set is a hyperspectral image in which Raman intensities are represented as a function of three coordinates: a spectral coordinate λ encoding the wavelength and two spatial coordinates x and y. Understanding CRM imaging data is challenging because of its complexity, size, and moderate signal-to-noise ratio. Spatial segmentation of CRM imaging data is a way to reveal regions of interest and is traditionally performed using nonsupervised clustering which relies on spectral domain-only information with the main drawback being the high sensitivity to noise. We present a new pipeline for spatial segmentation of CRM imaging data which combines preprocessing in the spectral and spatial domains with k-means clustering. Its core is the preprocessing routine in the spatial domain, edge-preserving denoising (EPD), which exploits the spatial relationships between Raman intensities acquired at neighboring pixels. Additionally, we propose to use both spatial correlation to identify Raman spectral features colocalized with defined spatial regions and confidence maps to assess the quality of spatial segmentation. For CRM data acquired from midsagittal Syrian hamster ( Mesocricetus auratus ) brain cryosections, we show how our pipeline benefits from the complex spatial-spectral relationships inherent in the CRM imaging data. EPD significantly improves the quality of spatial segmentation that allows us to extract the underlying structural and compositional information contained in the Raman microspectra.

  8. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Ferralis, Nicola; Carraro, Carlo

    2014-01-01

    Highlights: • H-intercalated epitaxial graphene–SiC interface studied with surface enhanced Raman. • Evolution of graphene and H–Si interface with UV-ozone, annealing and O-exposure. • H–Si interface and quasi-freestanding graphene are retained after UV-ozone treatment. • Enhanced ozonolytic reactivity at the edges of H-intercalated defected graphene. • Novel SERS method for characterizing near-surface graphene–substrate interfaces. - Abstract: A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer–SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm −1 corresponding to the Si-H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching

  9. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferralis, Nicola, E-mail: ferralis@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Carraro, Carlo [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720 (United States)

    2014-11-30

    Highlights: • H-intercalated epitaxial graphene–SiC interface studied with surface enhanced Raman. • Evolution of graphene and H–Si interface with UV-ozone, annealing and O-exposure. • H–Si interface and quasi-freestanding graphene are retained after UV-ozone treatment. • Enhanced ozonolytic reactivity at the edges of H-intercalated defected graphene. • Novel SERS method for characterizing near-surface graphene–substrate interfaces. - Abstract: A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer–SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm{sup −1} corresponding to the Si-H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching.

  10. Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

    2015-01-14

    Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

  11. Three-dimensional hybrid silicon nanostructures for surface enhanced Raman spectroscopy based molecular detection

    Science.gov (United States)

    Vendamani, V. S.; Nageswara Rao, S. V. S.; Venugopal Rao, S.; Kanjilal, D.; Pathak, A. P.

    2018-01-01

    Three-dimensional silver nanoparticles decorated vertically aligned Si nanowires (Si NWs) are effective surface-enhanced Raman spectroscopy (SERS) substrates for molecular detection at low concentration levels. The length of Si NWs prepared by silver assisted electroless etching is increased with an increase in etching time, which resulted in the reduced optical reflection in the visible region. These substrates were tested and optimized by measuring the Raman spectrum of standard dye Rhodamine 6G (R6G) of 10 nM concentration. Further, effective SERS enhancements of ˜105 and ˜104 were observed for the cytosine protein (concentration of 50 μM) and ammonium perchlorate (oxidizer used in explosives composition with a concentration of 10 μM), respectively. It is established that these three-dimensional SERS substrates yielded considerably higher enhancement factors for the detection of R6G when compared to previous reports. The sensitivity can further be increased and optimized since the Raman enhancement was found to increase with an increase in the density of silver nanoparticles decorated on the walls of Si NWs.

  12. Influences of Au ion radiation on microstructure and surface-enhanced Raman scattering of nanoporous copper

    Science.gov (United States)

    Wang, Jing; Hu, Zhaoyi; Li, Rui; Liu, Xiongjun; Xu, Chuan; Wang, Hui; Wu, Yuan; Fu, Engang; Lu, Zhaoping

    2018-05-01

    In this work, effects of Au ion irradiation on microstructure and surface-enhanced Raman scattering (SERS) performance of nanoporous copper (NPC) were investigated. It is found that the microstructure of NPC could be tailored by the ion irradiation dose, i.e., the pore size decreases while the ligament size significantly coarsens with the increase of the irradiation dose. In addition, the SERS enhancement for rhodamine 6G molecules was improved by Au ions irradiation at an appropriate dose. The underlying mechanism of the increase of SERS enhancement resulted from ion irradiation was discussed. Our findings could provide a new way to tune nanoporosity of nanoporous metals and improve their SERS performance.

  13. Nanogranular Au films deposited on carbon covered Si substrates for enhanced optical reflectivity and Raman scattering

    International Nuclear Information System (INIS)

    Bhuvana, T; Kumar, G V Pavan; Narayana, Chandrabhas; Kulkarni, G U

    2007-01-01

    Electroless deposition of gold has been carried out on Si(100) surfaces precoated with laser ablated carbon layers of different thicknesses, and the resulting substrates have been characterized by a host of techniques. We first established the porous nature of the amorphous carbon layer by Raman and profilometric measurements. The Au uptake from the plating solution was optimal at a carbon layer thickness of 90 nm, where we observed nanogranules of ∼60-70 nm, well separated from each other in the carbon matrix (mean interparticle spacing ∼7 nm). We believe that the observed nanostructure is a result of Au 3+ electroless reduction on the Si surface through porous channels present in the amorphous carbon matrix. Importantly, this nanostructured substrate exhibited high reflectivity in the near IR region besides being effective as a substrate for surface enhanced Raman scattering (SERS) measurements with enhancement factors up to 10 7

  14. Raman scattering enhancement in photon-plasmon resonance mediated metal-dielectric microcavity

    International Nuclear Information System (INIS)

    Guddala, Sriram; Narayana Rao, D.; Dwivedi, Vindesh K.; Vijaya Prakash, G.

    2013-01-01

    Here, we report the photon-plasmon interaction scheme and enhanced field strengths resulted into the amplification of phonon in a novel microcavity. A metal-dielectric microcavity, with unified cavity photonic mode and localized surface plasmon resonances, is visualized by impregnating the gold nanoparticles into the deep see-through nano-sized pores of porous silicon microcavity. The intense optical field strengths resulting from the photon-plasmon interactions are probed by both resonant and non-resonant Raman scattering experiments. Due to photon-plasmon-phonon interaction mechanism, several orders of enhancement in the intensity of scattered Raman Stokes photon (at 500 cm −1 ) are observed. Our metal nanoparticle-microcavity hybrid system shows the potential to improve the sensing figure of merit as well as the applications of plasmonics for optoelectronics, photovoltaics, and related technologies

  15. Polytetrafluorethylene-Au as a substrate for surface-enhanced Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Siegel Jakub

    2011-01-01

    Full Text Available Abstract This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.

  16. Surface-enhanced resonance Raman scattering spectroscopy of single R6G molecules

    Institute of Scientific and Technical Information of China (English)

    Zhou Zeng-Hui; Liu Li; Wang Gui-Ying; Xu Zhi-Zhan

    2006-01-01

    Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal silver clusters has been studied. Based on the great enhancement of the Raman signal and the quench of the fluorescence, the SERRS spectra of R6G were recorded for the samples of dye colloidal solution with different concentrations. Spectral inhomogeneity behaviours from single molecules in the dried sample films were observed with complementary evidences, such as spectral polarization, spectral diffusion, intensity fluctuation of vibrational lines and even "breathing" of the molecules. Sequential spectra observed from a liquid sample with an average of 0.3 dye molecules in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1 or 2 molecules. Difference between the SERRS spectra of R6G excited by linearly and circularly polarized light were experimentally measured.

  17. Probing cytochrome c in living mitochondria with surface-enhanced Raman spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A.; Evlyukhin, Andrey B.; Goodilin, Eugene A.

    2015-01-01

    Selective study of the electron transport chain components in living mitochondria is essential for fundamental biophysical research and for the development of new medical diagnostic methods. However, many important details of inter- and intramembrane mitochondrial processes have remained in shadow...... due to the lack of non-invasive techniques. Here we suggest a novel label-free approach based on the surface-enhanced Raman spectroscopy (SERS) to monitor the redox state and conformation of cytochrome c in the electron transport chain in living mitochondria. We demonstrate that SERS spectra of living...... mitochondria placed on hierarchically structured silver-ring substrates provide exclusive information about cytochrome c behavior under modulation of inner mitochondrial membrane potential, proton gradient and the activity of ATP-synthetase. Mathematical simulation explains the observed enhancement of Raman...

  18. Plasmonic optical antenna design for performing tip-enhanced Raman spectroscopy and microscopy

    International Nuclear Information System (INIS)

    Kharintsev, S S; Fishman, A I; Salakhov, M Kh; Hoffmann, G G

    2013-01-01

    This paper highlights optical plasmonic antennas designed with dc-pulsed low-voltage electrochemical etching of a gold wire for implementing tip-enhanced Raman scattering (TERS) measurements. We demonstrate a versatile electrochemical system that allows one to engineer TERS-active metallic gold tips with diverse shapes and sizes in a highly reproducible fashion. The underlying etching mechanism at a voltage-driven meniscus around a gold wire immersed into an electrolyte is discussed in detail. We show that the developed method is suitable to produce not only the simplest geometries such as cones and spheroids, but more complex designs. Attempts have been made to design plasmonic tapered antennas with quasi-uniformly spaced nano-sized bumps on the mesoscopic zone for the extra surface plasmon-light coupling. The capability of the patterned antenna to enhance and localize optical fields is demonstrated with near-field Raman microscopy and spectroscopy of single-walled carbon nanotubes bundles. (paper)

  19. Surface-enhanced Raman spectroscopy (SERS) using Ag nanoparticle films produced by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, C.A., E-mail: smythc2@tcd.ie [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Mirza, I.; Lunney, J.G.; McCabe, E.M. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Pulsed laser deposition (PLD) produces silver nanoparticle films. Black-Right-Pointing-Pointer These films can be used for surface-enhanced Raman spectroscopy (SERS). Black-Right-Pointing-Pointer Commercial film shows good SERS reproducibility but poor signal intensity. Black-Right-Pointing-Pointer PLD shows a good SERS response coupled with good reproducibility. - Abstract: Thin silver nanoparticle films, of thickness 7 nm, were deposited onto glass microslides using pulsed laser deposition (PLD). The films were then characterised using UV-vis spectroscopy and scanning transmission electron microscopy before Rhodamine 6G was deposited onto them for investigation using surface-enhanced Raman spectroscopy (SERS). The sensitivity obtained using SERS was compared to that obtained using a colloidal silver suspension and also to a commercial SERS substrate. The reproducibility of the films is also examined using statistical analysis.

  20. Surface enhanced Raman scattering in organic thin films covered with silver, indium and magnesium

    International Nuclear Information System (INIS)

    Salvan, Georgeta; Zahn, Dietrich R.T.; Paez, Beynor

    2004-01-01

    In situ resonant Raman spectroscopy was applied for the investigation of the interface formation between silver, indium and magnesium with polycrystalline organic semiconductor layers of 3,4,9,10-perylene tetra-carboxylic dianhydride (PTCDA). The spectral region of internal as well as external vibrational modes was recorded in order to achieve information related to the chemistry and the structure of the interface as well as to morphology of the metal layer. The experiments benefit from a strong enhancement of the internal mode scattering intensities which is induced by the rough morphology of deposited metals leading to surface enhanced Raman scattering (SERS). The external modes, on the other hand, are attenuated at different rates indicating that the diffusion of the metal atoms into the crystalline layers is highest for indium and lowest for magnesium

  1. Micro-Raman Imaging for Biology with Multivariate Spectral Analysis

    KAUST Repository

    Malvaso, Federica

    2015-05-05

    Raman spectroscopy is a noninvasive technique that can provide complex information on the vibrational state of the molecules. It defines the unique fingerprint that allow the identification of the various chemical components within a given sample. The aim of the following thesis work is to analyze Raman maps related to three pairs of different cells, highlighting differences and similarities through multivariate algorithms. The first pair of analyzed cells are human embryonic stem cells (hESCs), while the other two pairs are induced pluripotent stem cells (iPSCs) derived from T lymphocytes and keratinocytes, respectively. Although two different multivariate techniques were employed, ie Principal Component Analysis and Cluster Analysis, the same results were achieved: the iPSCs derived from T-lymphocytes show a higher content of genetic material both compared with the iPSCs derived from keratinocytes and the hESCs . On the other side, equally evident, was that iPS cells derived from keratinocytes assume a molecular distribution very similar to hESCs.

  2. Characterization of conductive nanobiomaterials derived from viral assemblies by low-voltage STEM imaging and Raman scattering

    International Nuclear Information System (INIS)

    Plascencia-Villa, Germán; Bahena, Daniel; José-Yacamán, Miguel; Carreño-Fuentes, Liliana; Palomares, Laura A; Ramírez, Octavio T

    2014-01-01

    New technologies require the development of novel nanomaterials that need to be fully characterized to achieve their potential. High-resolution low-voltage scanning transmission electron microscopy (STEM) has proven to be a very powerful technique in nanotechnology, but its use for the characterization of nanobiomaterials has been limited. Rotavirus VP6 self-assembles into nanotubular assemblies that possess an intrinsic affinity for Au ions. This property was exploited to produce hybrid nanobiomaterials by the in situ functionalization of recombinant VP6 nanotubes with gold nanoparticles. In this work, Raman spectroscopy and advanced analytical electron microscopy imaging with spherical aberration-corrected (Cs) STEM and nanodiffraction at low-voltage doses were employed to characterize nanobiomaterials. STEM imaging revealed the precise structure and arrangement of the protein templates, as well as the nanostructure and atomic arrangement of gold nanoparticles with high spatial sub-Angstrom resolution and avoided radiation damage. The imaging was coupled with backscattered electron imaging, ultra-high resolution scanning electron microscopy and x-ray spectroscopy. The hybrid nanobiomaterials that were obtained showed unique properties as bioelectronic conductive devices and showed enhanced Raman scattering by their precise arrangement into superlattices, displaying the utility of viral assemblies as functional integrative self-assembled nanomaterials for novel applications. (paper)

  3. Line-scan macro-scale Raman chemical imaging for authentication of powdered foods and ingredients

    Science.gov (United States)

    Adulteration and fraud for powdered foods and ingredients are rising food safety risks that threaten consumers’ health. In this study, a newly developed line-scan macro-scale Raman imaging system using a 5 W 785 nm line laser as excitation source was used to authenticate the food powders. The system...

  4. Quantitative imaging through a spectrograph : 2. stoichiometry mapping by Raman scattering

    NARCIS (Netherlands)

    Tolboom, R.A.L.; Dam, N.J.; Meulen, ter J.J.

    2004-01-01

    The Bayesian deconvolution algorithm described in a preceding paper [Appl. Opt. 43, 5669–5681 (2004)] is applied to measurement of the two-dimensional stoichiometry field in a combustible methane-air mixture by Raman imaging through a spectrograph. Stoichiometry (fuel equivalence ratio) is derived

  5. Quantitative imaging through a spectrograph. 2. Stoichiometry mapping by Raman scattering.

    NARCIS (Netherlands)

    Tolboom, R.A.L.; Dam, N.J.; Meulen, J.J. ter

    2004-01-01

    The Bayesian deconvolution algorithm described in a preceding paper [Appl. Opt. 43, 5669-5681 (2004)] is applied to measurement of the two-dimensional stoichiometry field in a combustible methane-air mixture by Raman imaging through a spectrograph. Stoichiometry (fuel equivalence ratio) is derived

  6. Noninvasive imaging of protein metabolic labeling in single human cells using stable isotopes and Raman microscopy

    NARCIS (Netherlands)

    van Manen, H.J.; Lenferink, Aufrid T.M.; Otto, Cornelis

    2008-01-01

    We have combined nonresonant Raman microspectroscopy and spectral imaging with stable isotope labeling by amino acids in cell culture (SILAC) to selectively detect the incorporation of deuterium-labeled phenylalanine, tyrosine, and methionine into proteins in intact, single HeLa cells. The C−D

  7. Investigation of Raman chemical imaging for detection of Lycopene changes in tomatoes during postharvest ripening

    Science.gov (United States)

    Lycopene is a major carotenoid in tomatoes and detecting changes in lycopene content can be used to monitor the ripening of tomatoes. Raman chemical imaging is a new technique that shows promise for mapping constituents of interest in complex food matrices. In this study, a benchtop point-scanning...

  8. Geometry of GLP on silver surface by surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Bao, PeiDi; Bao, Lang; Huang, TianQuan; Liu, XinMing; Wu, GuoFeng

    2000-05-01

    Leptospirosis is one of the most harmful zoonosis, it is a serious public health issue in some area of Sichuan province. Surface-Enhance Raman Scattering (SERS) Spectroscopy is an effective approach for the study of biomolecular adsorption on metal surface and provides information about the adsorbed species. Two samples of Leptospiral Glycolipoprotein (GLP-1) and GLP-2 which have different toxic effects have been obtained and investigated.

  9. Gold Nanoparticles Sliding on Recyclable Nanohoodoos-Engineered for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wu, Kaiyu; Li, Tao; Schmidt, Michael Stenbæk

    2018-01-01

    Robust, macroscopically uniform, and highly sensitive substrates for surface-enhanced Raman spectroscopy (SERS) are fabricated using wafer-scale block copolymer lithography. The substrate consists of gold nanoparticles that can slide and aggregate on dense and recyclable alumina/silicon nanohoodo...... for obtaining cost-effective, high-quality, and reliable SERS spectra, facilitating a wide and simple use of SERS for both laboratorial and commercial applications...

  10. Effects of corner radius on periodic nanoantenna for surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Chao, Bo-Kai; Lin, Shih-Che; Nien, Li-Wei; Hsueh, Chun-Hway; Li, Jia-Han

    2015-01-01

    Corner radius is a concept to approximate the fabrication limitation due to the effective beam broadening at the corner in using electron-beam lithography. The purpose of the present study is to investigate the effects of corner radius on the electromagnetic field enhancement and resonance wavelength for three periodic polygon dimers of bowtie, twin square, and twin pentagon. The enhancement factor of surface-enhanced Raman spectroscopy due to the localized surface plasmon resonances in fabricated gold bowtie nanostructures was investigated using both Raman spectroscopy and finite-difference time-domain simulations. The simulated enhancement factor versus corner radius relation was in agreement with measurements and it could be fitted by a power-law relation. In addition, the resonance wavelength showed blue shift with the increasing corner radius because of the distribution of concentrated charges in a larger area. For different polygons, the corner radius instead of the tip angle is the dominant factor of the electromagnetic field enhancement because the surface charges tend to localize at the corner. Greater enhancements can be obtained by having both the smaller gap and sharper corner although the corner radius effect on intensity enhancement is less than the gap size effect. (paper)

  11. Silver Nanoparticle-Enhanced Resonance Raman Sensor of Chromium(III) in Seawater Samples.

    Science.gov (United States)

    Ly, Nguyễn Hoàng; Joo, Sang-Woo

    2015-04-29

    Tris(hydroxymethyl)aminomethane ethylenediaminetetraacetic acid (Tris-EDTA), upon binding Cr(III) in aqueous solutions at pH 8.0 on silver nanoparticles (AgNPs), was found to provide a sensitive and selective Raman marker band at ~563 cm-1, which can be ascribed to the metal-N band. UV-Vis absorption spectra also supported the aggregation and structural change of EDTA upon binding Cr(III). Only for Cr(III) concentrations above 500 nM, the band at ~563 cm-1 become strongly intensified in the surface-enhanced Raman scattering spectra. This band, due to the metal-EDTA complex, was not observed in the case of 50 mM of K+, Cd2+, Mg2+, Ca2+, Mn2+, Co2+, Na+, Cu2+, NH4+, Hg2+, Ni2+, Fe3+, Pb2+, Fe2+, and Zn2+ ions. Seawater samples containing K, Mg, Ca, and Na ion concentrations higher than 8 mM also showed the characteristic Raman band at ~563 cm-1 above 500 nM, validating our method. Our approach may be useful in detecting real water samples by means of AgNPs and Raman spectroscopy.

  12. Protein–nanoparticle interaction in bioconjugated silver nanoparticles: A transmission electron microscopy and surface enhanced Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Reymond-Laruinaz, Sébastien; Saviot, Lucien; Potin, Valérie; Marco de Lucas, María del Carmen, E-mail: delucas@u-bourgogne.fr

    2016-12-15

    Highlights: • Synthesis of protein-conjugated Ag nanoparticles (NPs) in absence of citrates. • NPs size and protein layer thickness determined by TEM. • SERS spectra showed the chemisorption of proteins on the surface of Ag-NPs. - Abstract: Understanding the mechanisms of interaction between proteins and noble metal nanoparticles (NPs) is crucial to extend the use of NPs in biological applications and nanomedicine. We report the synthesis of Ag-NPs:protein bioconjugates synthesized in total absence of citrates or other stabilizing agents in order to study the NP-protein interaction. Four common proteins (lysozyme, bovine serum albumin, cytochrome-C and hemoglobin) were used in this work. Transmission electron microscopy (TEM) and surface enhanced Raman spectroscopy (SERS) were mainly used to study these bioconjugated NPs. TEM images showed Ag NPs with sizes in the 5–40 nm range. The presence of a protein layer surrounding the Ag NPs was also observed by TEM. Moreover, the composition at different points of single bioconjugated NPs was probed by electron energy loss spectroscopy (EELS). The thickness of the protein layer varies in the 3–15 nm range and the Ag NPs are a few nanometers away. This allowed to obtain an enhancement of the Raman signal of the proteins in the analysis of water suspensions of bioconjugates. SERS results showed a broadening of the Raman bands of the proteins which we attribute to the contribution of different configurations of the proteins adsorbed on the Ag NPs surface. Moreover, the assignment of an intense and sharp peak in the low-frequency range to Ag–N vibrations points to the chemisorption of the proteins on the Ag-NPs surface.

  13. Photochemical decoration of gold nanoparticles on polymer stabilized magnetic microspheres for determination of adenine by surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Alula, Melisew Tadele; Yang, Jyisy

    2015-01-01

    Magnetic microspheres decorated with gold nanoparticles (AuNPs) were prepared and used for the determination of adenine by surface-enhanced Raman scattering (SERS). Magnetic particles were first synthesized by coprecipitation of solutions containing iron(II) and iron(III) ions with ammonium hydroxide. Subsequently, the magnetic particles were suspended into a solution of poly(divinylbenzene-co-methyl methacrylate) to yield polymer-stabilized magnetic microspheres. These were further decorated with AuNPs via a new photochemical reduction method. The magnetic microspheres were characterized by XRD patterns and SEM images. They are shown to represent highly SERS-active substrates by giving an enhancement by almost 7 orders of magnitude compared to conventional Raman spectroscopy. Several factors that affect the photochemical reduction to form the AuNPs were examined. It is found that the concentration of gold ion, UV irradiation time, and citrate concentration have more impact on the reaction rate than on the morphologies of the AuNPs. The gold-decorated magnetic microspheres are highly stable in aqueous solution and capable of concentrating nucleobases. A linear response of the SERS signal to adenine in concentrations up to 10 μM is found, with a linear regression coefficient of 0.997. The detection limit is estimated to a few hundreds of nM (at an SNR of 3). Based on its specific Raman peak at 734 cm −1 , adenine can be selectively determined without interference by other nucleobases, and a recovery higher than 95 % could be obtained. (author)

  14. Protein–nanoparticle interaction in bioconjugated silver nanoparticles: A transmission electron microscopy and surface enhanced Raman spectroscopy study

    International Nuclear Information System (INIS)

    Reymond-Laruinaz, Sébastien; Saviot, Lucien; Potin, Valérie; Marco de Lucas, María del Carmen

    2016-01-01

    Highlights: • Synthesis of protein-conjugated Ag nanoparticles (NPs) in absence of citrates. • NPs size and protein layer thickness determined by TEM. • SERS spectra showed the chemisorption of proteins on the surface of Ag-NPs. - Abstract: Understanding the mechanisms of interaction between proteins and noble metal nanoparticles (NPs) is crucial to extend the use of NPs in biological applications and nanomedicine. We report the synthesis of Ag-NPs:protein bioconjugates synthesized in total absence of citrates or other stabilizing agents in order to study the NP-protein interaction. Four common proteins (lysozyme, bovine serum albumin, cytochrome-C and hemoglobin) were used in this work. Transmission electron microscopy (TEM) and surface enhanced Raman spectroscopy (SERS) were mainly used to study these bioconjugated NPs. TEM images showed Ag NPs with sizes in the 5–40 nm range. The presence of a protein layer surrounding the Ag NPs was also observed by TEM. Moreover, the composition at different points of single bioconjugated NPs was probed by electron energy loss spectroscopy (EELS). The thickness of the protein layer varies in the 3–15 nm range and the Ag NPs are a few nanometers away. This allowed to obtain an enhancement of the Raman signal of the proteins in the analysis of water suspensions of bioconjugates. SERS results showed a broadening of the Raman bands of the proteins which we attribute to the contribution of different configurations of the proteins adsorbed on the Ag NPs surface. Moreover, the assignment of an intense and sharp peak in the low-frequency range to Ag–N vibrations points to the chemisorption of the proteins on the Ag-NPs surface.

  15. Enhanced Raman scattering and nonlinear conductivity in Ag-doped hollow ZnO microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, Joseph W.; Levie, Harold W.; McCall, Scott K.; Teslich, Nick E.; Wall, Mark A.; Orme, Christine A.; Matthews, Manyalibo J. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2012-10-15

    Hollow spherical ZnO particles doped with Ag were synthesized with a two-step oxidation and sublimation furnace annealing process. Ag nanoparticle precipitates, as observed by transmission electron microscopy, were present in the polycrystalline ZnO matrix at Ag concentrations below 0.02 mol%, significantly below the 0.8 mol% solubility limit for Ag in ZnO. Enhanced Raman scattering of ZnO phonon modes is observed, increasing with Ag nanoparticle concentration. A further enhancement in Raman scattering due to resonance effects was observed for LO phonons excited by 2.33-eV photons as compared with Raman scattering under 1.96-eV excitation. Room-temperature photoluminescence spectra showed both a near-band-edge emission due to free exciton transitions and a mid-gap transition due to the presence of singly ionized oxygen vacancies. ZnO:Ag particles were measured electrically in a packed column and in monolithic form, and in both cases displayed nonlinear current-voltage characteristics similar to those previously observed in sintered ZnO:Ag monoliths where Ag-enhanced disorder at grain boundaries is thought to control current transport. We demonstrate therefore that Ag simultaneously modifies the electrical and optical properties of ZnO particles through the introduction of vacancies and other defects. (orig.)

  16. A surface enhanced Raman scattering spectroscopic study of UO{sub 2}{sup 2+} at trace concentration

    Energy Technology Data Exchange (ETDEWEB)

    Franzen, Carola [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Carstensen, Lale [Technische Univ. Dresden (Germany); Firkala, T. [Helmholtz Institute Freiberg for Resource Technology, Freiberg (Germany); Steudtner, Robin [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2017-06-01

    Techniques for rapid screening of uranium in environmental samples are needed. This study entails the development of Surface-Enhanced Raman scattering (SERS) spectroscopy for analyzing uranium(VI) in aqueous media with improved sensitivity.

  17. Fiber array based hyperspectral Raman imaging for chemical selective analysis of malaria-infected red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Brückner, Michael [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Becker, Katja [Justus Liebig University Giessen, Biochemistry and Molecular Biology, 35392 Giessen (Germany); Popp, Jürgen [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Friedrich Schiller University Jena, Institute for Physical Chemistry, 07745 Jena (Germany); Friedrich Schiller University Jena, Abbe Centre of Photonics, 07745 Jena (Germany); Frosch, Torsten, E-mail: torsten.frosch@uni-jena.de [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Friedrich Schiller University Jena, Institute for Physical Chemistry, 07745 Jena (Germany); Friedrich Schiller University Jena, Abbe Centre of Photonics, 07745 Jena (Germany)

    2015-09-24

    A new setup for Raman spectroscopic wide-field imaging is presented. It combines the advantages of a fiber array based spectral translator with a tailor-made laser illumination system for high-quality Raman chemical imaging of sensitive biological samples. The Gaussian-like intensity distribution of the illuminating laser beam is shaped by a square-core optical multimode fiber to a top-hat profile with very homogeneous intensity distribution to fulfill the conditions of Koehler. The 30 m long optical fiber and an additional vibrator efficiently destroy the polarization and coherence of the illuminating light. This homogeneous, incoherent illumination is an essential prerequisite for stable quantitative imaging of complex biological samples. The fiber array translates the two-dimensional lateral information of the Raman stray light into separated spectral channels with very high contrast. The Raman image can be correlated with a corresponding white light microscopic image of the sample. The new setup enables simultaneous quantification of all Raman spectra across the whole spatial area with very good spectral resolution and thus outperforms other Raman imaging approaches based on scanning and tunable filters. The unique capabilities of the setup for fast, gentle, sensitive, and selective chemical imaging of biological samples were applied for automated hemozoin analysis. A special algorithm was developed to generate Raman images based on the hemozoin distribution in red blood cells without any influence from other Raman scattering. The new imaging setup in combination with the robust algorithm provides a novel, elegant way for chemical selective analysis of the malaria pigment hemozoin in early ring stages of Plasmodium falciparum infected erythrocytes. - Highlights: • Raman hyperspectral imaging allows for chemical selective analysis of biological samples with spatial heterogeneity. • A homogeneous, incoherent illumination is essential for reliable

  18. Fiber array based hyperspectral Raman imaging for chemical selective analysis of malaria-infected red blood cells

    International Nuclear Information System (INIS)

    Brückner, Michael; Becker, Katja; Popp, Jürgen; Frosch, Torsten

    2015-01-01

    A new setup for Raman spectroscopic wide-field imaging is presented. It combines the advantages of a fiber array based spectral translator with a tailor-made laser illumination system for high-quality Raman chemical imaging of sensitive biological samples. The Gaussian-like intensity distribution of the illuminating laser beam is shaped by a square-core optical multimode fiber to a top-hat profile with very homogeneous intensity distribution to fulfill the conditions of Koehler. The 30 m long optical fiber and an additional vibrator efficiently destroy the polarization and coherence of the illuminating light. This homogeneous, incoherent illumination is an essential prerequisite for stable quantitative imaging of complex biological samples. The fiber array translates the two-dimensional lateral information of the Raman stray light into separated spectral channels with very high contrast. The Raman image can be correlated with a corresponding white light microscopic image of the sample. The new setup enables simultaneous quantification of all Raman spectra across the whole spatial area with very good spectral resolution and thus outperforms other Raman imaging approaches based on scanning and tunable filters. The unique capabilities of the setup for fast, gentle, sensitive, and selective chemical imaging of biological samples were applied for automated hemozoin analysis. A special algorithm was developed to generate Raman images based on the hemozoin distribution in red blood cells without any influence from other Raman scattering. The new imaging setup in combination with the robust algorithm provides a novel, elegant way for chemical selective analysis of the malaria pigment hemozoin in early ring stages of Plasmodium falciparum infected erythrocytes. - Highlights: • Raman hyperspectral imaging allows for chemical selective analysis of biological samples with spatial heterogeneity. • A homogeneous, incoherent illumination is essential for reliable

  19. Plasmonic nanocarrier grid-enhanced Raman sensor for studies of anticancer drug delivery.

    Science.gov (United States)

    Kurzątkowska, Katarzyna; Santiago, Ty; Hepel, Maria

    2017-05-15

    Targeted drug delivery systems using nanoparticle nanocarriers offer remarkable promise for cancer therapy by discriminating against devastating cytotoxicity of chemotherapeutic drugs to healthy cells. To aid in the development of new drug nanocarriers, we propose a novel plasmonic nanocarrier grid-enhanced Raman sensor which can be applied for studies and testing of drug loading onto the nanocarriers, attachment of targeting ligands, dynamics of drug release, assessment of nanocarrier stability in biological environment, and general capabilities of the nanocarrier. The plasmonic nanogrid sensor offers strong Raman enhancement due to the overlapping plasmonic fields emanating from the nearest-neighbor gold nanoparticle nanocarriers and creating the enhancement "hot spots". The sensor has been tested for immobilization of an anticancer drug gemcitabine (2',2'-difluoro-2'-deoxycytidine, GEM) which is used in treatment of pancreatic tumors. The drawbacks of currently applied treatment include high systemic toxicity, rapid drug decay, and low efficacy (ca. 20%). Therefore, the development of a targeted GEM delivery system is highly desired. We have demonstrated that the proposed nanocarrier SERS sensor can be utilized to investigate attachment of targeting ligands to nanocarriers (attachment of folic acid ligand recognized by folate receptors of cancer cells is described). Further testing of the nanocarrier SERS sensor involved drug release induced by lowering pH and increasing GSH levels, both occurring in cancer cells. The proposed sensor can be utilized for a variety of drugs and targeting ligands, including those which are Raman inactive, since the linkers can act as the Raman markers, as illustrated with mercaptobenzoic acid and para-aminothiophenol. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Surface Enhanced Raman Scattering Substrates Made by Oblique Angle Deposition: Methods and Applications

    Directory of Open Access Journals (Sweden)

    Hin On Chu

    2017-02-01

    Full Text Available Surface Enhanced Raman Spectroscopy presents a rapid, non-destructive method to identify chemical and biological samples with up to single molecule sensitivity. Since its discovery in 1974, the technique has become an intense field of interdisciplinary research, typically generating >2000 publications per year since 2011. The technique relies on the localised surface plasmon resonance phenomenon, where incident light can couple with plasmons at the interface that result in the generation of an intense electric field. This field can propagate from the surface from the metal-dielectric interface, so molecules within proximity will experience more intense Raman scattering. Localised surface plasmon resonance wavelength is determined by a number of factors, such as size, geometry and material. Due to the requirements of the surface optical response, Ag and Au are typical metals used for surface enhanced Raman applications. These metals then need to have nano features that improve the localised surface plasmon resonance, several variants of these substrates exist; surfaces can range from nanoparticles in a suspension, electrochemically roughened electrodes to metal nanostructures on a substrate. The latter will be the focus of this review, particularly reviewing substrates made by oblique angle deposition. Oblique angle deposition is the technique of growing thin films so that the material flux is not normal to the surface. Films grown in this fashion will possess nanostructures, due to the atomic self-shadowing effect, that are dependent mainly on the deposition angle. Recent developments, applications and highlights of surface enhanced Raman scattering substrates made by oblique angle deposition will be reviewed.

  1. Raman Hyperspectral Imaging for Detection of Watermelon Seeds Infected with Acidovorax citrulli.

    Science.gov (United States)

    Lee, Hoonsoo; Kim, Moon S; Qin, Jianwei; Park, Eunsoo; Song, Yu-Rim; Oh, Chang-Sik; Cho, Byoung-Kwan

    2017-09-23

    The bacterial infection of seeds is one of the most important quality factors affecting yield. Conventional detection methods for bacteria-infected seeds, such as biological, serological, and molecular tests, are not feasible since they require expensive equipment, and furthermore, the testing processes are also time-consuming. In this study, we use the Raman hyperspectral imaging technique to distinguish bacteria-infected seeds from healthy seeds as a rapid, accurate, and non-destructive detection tool. We utilize Raman hyperspectral imaging data in the spectral range of 400-1800 cm -1 to determine the optimal band-ratio for the discrimination of watermelon seeds infected by the bacteria Acidovorax citrulli using ANOVA. Two bands at 1076.8 cm -1 and 437 cm -1 are selected as the optimal Raman peaks for the detection of bacteria-infected seeds. The results demonstrate that the Raman hyperspectral imaging technique has a good potential for the detection of bacteria-infected watermelon seeds and that it could form a suitable alternative to conventional methods.

  2. Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Junwei [Iowa State Univ., Ames, IA (United States)

    1999-11-08

    Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO2 were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO2, large photoelectrocatalytic effect for the reduction of CO2 was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO2 in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.

  3. Microscopic theory of cavity-enhanced single-photon emission from optical two-photon Raman processes

    Science.gov (United States)

    Breddermann, Dominik; Praschan, Tom; Heinze, Dirk; Binder, Rolf; Schumacher, Stefan

    2018-03-01

    We consider cavity-enhanced single-photon generation from stimulated two-photon Raman processes in three-level systems. We compare four fundamental system configurations, one Λ -, one V-, and two ladder (Ξ -) configurations. These can be realized as subsystems of a single quantum dot or of quantum-dot molecules. For a new microscopic understanding of the Raman process, we analyze the Heisenberg equation of motion applying the cluster-expansion scheme. Within this formalism an exact and rigorous definition of a cavity-enhanced Raman photon via its corresponding Raman correlation is possible. This definition for example enables us to systematically investigate the on-demand potential of Raman-transition-based single-photon sources. The four system arrangements can be divided into two subclasses, Λ -type and V-type, which exhibit strongly different Raman-emission characteristics and Raman-emission probabilities. Moreover, our approach reveals whether the Raman path generates a single photon or just induces destructive quantum interference with other excitation paths. Based on our findings and as a first application, we gain a more detailed understanding of experimental data from the literature. Our analysis and results are also transferable to the case of atomic three-level-resonator systems and can be extended to more complicated multilevel schemes.

  4. Application of surface-enhanced Raman spectroscopy (SERS) for cleaning verification in pharmaceutical manufacture.

    Science.gov (United States)

    Corrigan, Damion K; Cauchi, Michael; Piletsky, Sergey; Mccrossen, Sean

    2009-01-01

    Cleaning verification is the process by which pharmaceutical manufacturing equipment is determined as sufficiently clean to allow manufacture to continue. Surface-enhanced Raman spectroscopy (SERS) is a very sensitive spectroscopic technique capable of detection at levels appropriate for cleaning verification. In this paper, commercially available Klarite SERS substrates were employed in order to obtain the necessary enhancement of signal for the identification of chemical species at concentrations of 1 to 10 ng/cm2, which are relevant to cleaning verification. The SERS approach was combined with principal component analysis in the identification of drug compounds recovered from a contaminated steel surface.

  5. Enhanced stimulated Raman scattering by femtosecond ultraviolet plasma grating in water

    Science.gov (United States)

    Liu, Fengjiang; Yuan, Shuai; He, Boqu; Nan, Junyi; Khan, Abdul Qayyum; Ding, Liang'en; Zeng, Heping

    2018-02-01

    Efficient forward stimulated Raman scattering (SRS) was observed along 400-nm femtosecond (fs) laser filaments in water. SRS conversion dominated over self-phase modulation induced continuum generation as the input pulse energy was above 4 μJ (˜30 Pcr), implying that plasma in the aqueous filamentation channel played an important role in compensating for the group velocity walk-off between the pump and Stokes pulses. By overlapping two synchronous fs 400-nm filaments to form plasma grating in water, significant enhancement of SRS conversion was observed. Such a SRS enhancement originated from the ultrahigh plasma density in the intersection region of the preformed plasma grating.

  6. Surface-enhanced Raman scattering on gold nanorod pairs with interconnection bars of different widths

    KAUST Repository

    Yue, Weisheng

    2012-08-01

    We demonstrate that surface-enhanced Raman scattering (SERS) enhancement could be tuned by adjusting the width of a connection bar at the bottom of a gold nanorod pair. Arrays of gold nanorod pairs with interconnection bars of different widths at the bottom of the interspace were fabricated by electron-beam lithography and used for the SERS study. Rhodamine 6G (R6G) was used as the probe molecule for the SERS. In addition to the large SERS enhancement observed in the nanostructured substrates, the SERS enhancement increases as the width of the connection bar increases. This result provides an important method for tuning SERS enhancement. Numerical simulations of electromagnetic properties on the nanostructures were performed with CST Microwave Studio, and the results correspond well with the experimental observations. © 2012 Elsevier B.V. All rights reserved.

  7. Implantation and growth of dendritic gold nanostructures on graphene derivatives: electrical property tailoring and Raman enhancement.

    Science.gov (United States)

    Jasuja, Kabeer; Berry, Vikas

    2009-08-25

    Interfacing electron-rich metal nanoparticles with graphene derivatives can sensitively regulate the properties of the resultant hybrid with potential applications in metal-doped graphene field-effect transistors (FETs), surface-enhanced Raman spectroscopy, and catalysis. Here, we show that by controlling the rate of diffusion and catalytic reduction of gold ions on graphene oxide (GO), dendritic "snowflake-shaped" gold nanostructures (SFGNs) can be templated on graphene. The structural features of the SFGNs and their interfacing mechanism with GO were characterized by microscopic analysis and Raman-scattering. We demonstrate that (a) SFGNs grow on GO-surface via diffusion limited aggregation; (b) SFGN's morphology (dendritic to globular), size (diameter of 150-500 nm and a height of 45-55 nm), coverage density, and dispersion stability can be controlled by regulating the chemiophysical forces; (c) SFGNs enhance the Raman signal by 2.5 folds; and (d) SFGNs act as antireduction resist during GO-SFGN's chemical reduction. Further, the SFGNs interfacing with graphene reduces the apparent band gap (from 320 to 173 meV) and the Schottky barrier height (from 126 to 56 meV) of the corresponding FET.

  8. Dimensional scale effects on surface enhanced Raman scattering efficiency of self-assembled silver nanoparticle clusters

    International Nuclear Information System (INIS)

    Fasolato, C.; Domenici, F.; De Angelis, L.; Luongo, F.; Postorino, P.; Sennato, S.; Mura, F.; Costantini, F.; Bordi, F.

    2014-01-01

    A study of the Surface Enhanced Raman Scattering (SERS) from micrometric metallic nanoparticle aggregates is presented. The sample is obtained from the self-assembly on glass slides of micro-clusters of silver nanoparticles (60 and 100 nm diameter), functionalized with the organic molecule 4-aminothiophenol in water solution. For nanoparticle clusters at the micron scale, a maximum enhancement factor of 10 9 is estimated from the SERS over the Raman intensity ratio normalized to the single molecule contribution. Atomic force microscopy, correlated to spatially resolved Raman measurements, allows highlighting the connection between morphology and efficiency of the plasmonic system. The correlation between geometric features and SERS response of the metallic structures reveals a linear trend of the cluster maximum scattered intensity as a function of the surface area of the aggregate. On given clusters, the intensity turns out to be also influenced by the number of stacking planes of the aggregate, thus suggesting a plasmonic waveguide effect. The linear dependence results weakened for the largest area clusters, suggesting 30 μm 2 as the upper limit for exploiting the coherence over large scale of the plasmonic response.

  9. Surface-enhanced raman spectroscopic studies of ellagic acid in silver colloids

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jang; Cheong, Byeong Seo; Cho, Han Gook [Dept. of Chemistry, Incheon National University, Incheon (Korea, Republic of)

    2015-06-15

    Surface-enhanced Raman scattering (SERS) spectroscopy has been applied for the vibrational characterization of ellagic acid (EA), a natural organic dye, using citrate-reduced silver colloids. The infrared and FT-Raman spectra of EA in the solid state were examined for comparison. Spectral assignments of the observed bands were aided by density functional theory (DFT) calculations employing the B3LYP functional. The variations in the SERS spectrum with pH and excitation wavelength were analyzed to gain information on the adsorption- and pH-dependent behaviors of the natural dye on the metal surface. On the basis of the observed spectral features and DFT calculations, the adsorption configuration of EA on the silver metal surface is proposed.

  10. Surface-enhanced Raman Spectroscopy of Ethephone Adsorbed on Silver Surface

    International Nuclear Information System (INIS)

    Lee, Chul Jae; Kim, Hee Jin; Karim, Mohammad Rezaul; Lee, Mu Sang

    2006-01-01

    We investigated the Surface-enhanced Raman Spectroscopy (SERS) spectrum of ethephone (2- chloroethylphosphonic acid). We observed significant signals in the ordinary Raman spectrum for solid-state ethephone as well as when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids that were prepared by the γ - irradiation method. The influence of pH and the influence of anion (Cl - , Br - , I - ) on the adsorption orientation were investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions. The chlorine atom or the chlorine and two oxygen atoms were adsorbed on the colloidal silver surface. Among halide ions, Br - and I - were more strongly adsorbed on the colloidal silver surfaces. As a result, the adsorption of ethephone was less effective due to their steric hinderance

  11. Evidence for anisotropic excitonlike enhancement of the Raman scattering from La2CuO4

    International Nuclear Information System (INIS)

    Weber, W.H.; Peters, C.R.; Wanklyn, B.M.; Chen, C.; Watts, B.E.

    1988-01-01

    Polarized Raman studies on oriented single crystals of La 2 CuO 4 yield α/sub z//sub z/ spectra with narrow lines at 429 and 228 cm/sup -1/ that are identified as the two A 1 /sub g/ modes expected for the tetragonal K 2 NiF 4 structure; α/sub x//sub z/ spectra with one line at 228 cm/sup -1/ that has E/sub g/ symmetry; and α/sub x//sub x/ spectra with numerous peaks that are due to normally forbidden phonon excitations. The α/sub x//sub x/ spectra also show strong second-order features, suggesting a highly anisotropic, excitonlike enhancement of the Raman scattering

  12. Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse

    Science.gov (United States)

    Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

    2018-05-01

    Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10‑9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

  13. Detection of mast cell secretion by using surface enhanced Raman scattering

    Science.gov (United States)

    Li, Juan; Li, Ren; Zheng, Liqin; Wang, Yuhua; Xie, Shusen; Lin, Juqiang

    2016-10-01

    Acupuncture can cause a remarkable increase in degranulation of the mast cells, which has attracted the interest of researchers since the 1980s. Surface-enhanced Raman scattering (SERS) could obtain biochemical information with high sensitivity and specificity. In this study, SERS was used to detect the degree of degranulation of mast cells according to different incubate time. Mast cells was incubated with culture medium for 0 h, 12 h and 24 h, then centrifuge the culture medium, decant the supernatant, and discard the mast cell. SERS was performed to obtain the biochemical fingerprinting signatures of the centrifuged medium. The spectra data are then analyzed by spectral peaks attribution and the principal component analysis (PCA). The measured Raman spectra of the two groups were separated well by PCA. It indicated that mast cells had secreted some substances into cultured medium though degranulation did not happen.

  14. Application of Raman spectroscopy and surface-enhanced Raman scattering to the analysis of synthetic dyes found in ballpoint pen inks.

    Science.gov (United States)

    Geiman, Irina; Leona, Marco; Lombardi, John R

    2009-07-01

    The applicability of Raman spectroscopy and surface-enhanced Raman scattering (SERS) to the analysis of synthetic dyes commonly found in ballpoint inks was investigated in a comparative study. Spectra of 10 dyes were obtained using a dispersive system (633 nm, 785 nm lasers) and a Fourier transform system (1064 nm laser) under different analytical conditions (e.g., powdered pigments, solutions, thin layer chromatography [TLC] spots). While high fluorescence background and poor spectral quality often characterized the normal Raman spectra of the dyes studied, SERS was found to be generally helpful. Additionally, dye standards and a single ballpoint ink were developed on a TLC plate following a typical ink analysis procedure. SERS spectra were successfully collected directly from the TLC plate, thus demonstrating a possible forensic application for the technique.

  15. Infrared image enhancement with learned features

    Science.gov (United States)

    Fan, Zunlin; Bi, Duyan; Ding, Wenshan

    2017-11-01

    Due to the variation of imaging environment and limitations of infrared imaging sensors, infrared images usually have some drawbacks: low contrast, few details and indistinct edges. Hence, to promote the applications of infrared imaging technology, it is essential to improve the qualities of infrared images. To enhance image details and edges adaptively, we propose an infrared image enhancement method under the proposed image enhancement scheme. On the one hand, on the assumption of high-quality image taking more evident structure singularities than low-quality images, we propose an image enhancement scheme that depends on the extractions of structure features. On the other hand, different from the current image enhancement algorithms based on deep learning networks that try to train and build the end-to-end mappings on improving image quality, we analyze the significance of first layer in Stacked Sparse Denoising Auto-encoder and propose a novel feature extraction for the proposed image enhancement scheme. Experiment results prove that the novel feature extraction is free from some artifacts on the edges such as blocking artifacts, ;gradient reversal;, and pseudo contours. Compared with other enhancement methods, the proposed method achieves the best performance in infrared image enhancement.

  16. Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2.

    Science.gov (United States)

    Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T; Zhang, Xu; Rodriguez-Nieva, Joaquin F; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S

    2014-06-11

    Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) molecule as a probe. This molecule can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm(-1)) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm(-1)) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chemical bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may

  17. Normal Raman and surface enhanced Raman spectroscopic experiments with thin layer chromatography spots of essential amino acids using different laser excitation sources

    Science.gov (United States)

    István, Krisztina; Keresztury, Gábor; Szép, Andrea

    2003-06-01

    A comparative study of the feasibility and efficiency of Raman spectroscopic detection of thin layer chromatography (TLC) spots of some weak Raman scatterers (essential amino acids, namely, glycine and L-forms of alanine, serine, valine, proline, hydroxyproline, and phenylalanine) was carried out using four different visible and near-infrared (NIR) laser radiations with wavelengths of 532, 633, 785, and 1064 nm. Three types of commercial TLC plates were tested and the possibility of inducing surface enhanced Raman scattering (SERS) by means of Ag-sol was also investigated. The spectra obtained from spotted analytes adsorbed on TLC plates were of very different quality strongly depending on the excitation wavelength, the wetness of the samples, and the compounds examined. The best results were obtained with the simple silica TLC plate, and it has been established that the longest wavelength (lowest energy) NIR excitation of a Nd:YAG laser is definitely more suitable for generating normal Raman scattering of analyte spots than any of the visible radiations. Concerning SERS with application of Ag-sol to the TLC spots, 1-3 orders of magnitude enhancement was observed with wet samples, the greatest with the 532 nm radiation and gradually smaller with the longer wavelength excitations. It is shown, however, that due to severe adsorption-induced spectral distortions and increased sensitivity to microscopic inhomogeneity of the sample, none of the SERS spectra obtained with the dispersive Raman microscope operating in the visible region were superior to the best NIR normal FT-Raman spectra, as far as sample identification is concerned.

  18. Internalization kinetics and cytoplasmic localization of functionalized diatomite nanoparticles in cancer cells by Raman imaging.

    Science.gov (United States)

    Managò, Stefano; Migliaccio, Nunzia; Terracciano, Monica; Napolitano, Michela; Martucci, Nicola M; De Stefano, Luca; Rendina, Ivo; De Luca, Anna Chiara; Lamberti, Annalisa; Rea, Ilaria

    2018-04-01

    Porous biosilica nanoparticles obtained from diatomites (DNPs) have been recently demonstrated to be non-toxic nanovectors of therapeutic agents in cancer cells. In this work, the internalization kinetics and intracellular spatial distribution of functionalized DNPs incubated with human lung epidermoid carcinoma cell line (H1355) up to 72 hours are investigated by Raman imaging. The label-free Raman results are compared with confocal fluorescence microscopy and photoluminescence (PL) data. Raman bands specifically assigned to DNPs and cellular components provide evidence that the nanovectors are internalized and co-localize with lipid environments. A considerable DNPs uptake in cells is observed within 6 hours, with equilibrium being achieved after 18 hours. The obtained data show the presence of DNPs up to 72 hours, without damage to cell viability or morphology. The PL measurements performed on DNPs not penetrating the cells at different incubation times are strongly correlated with the results obtained by Raman imaging and confocal microscopy analyses. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Multi-metal, Multi-wavelength Surface-Enhanced Raman Spectroscopy Detection of Neurotransmitters.

    Science.gov (United States)

    Moody, Amber S; Sharma, Bhavya

    2018-04-05

    The development of a sensor for the rapid and sensitive detection of neurotransmitters could provide a pathway for the diagnosis of neurological diseases, leading to the discovery of more effective treatment methods. We investigate the use of surface enhanced Raman spectroscopy (SERS) based sensors for the rapid detection of melatonin, serotonin, glutamate, dopamine, GABA, norepinephrine, and epinephrine. Previous studies have demonstrated SERS detection of neurotransmitters; however, there has been no comprehensive study on the effect of the metal used as the SERS substrate or the excitation wavelength used for detection. Here, we present the detection of 7 neurotransmitters using both silver and gold nanoparticles at excitation wavelengths of 532, 633, and 785 nm. Over the range of wavelengths investigated, the SERS enhancement on the silver and gold nanoparticles varies, with an average enhancement factor of 10 5 -10 6 . The maximum SERS enhancement occurs at an excitation wavelength of 785 nm for the gold nanoparticles and at 633 nm for the silver nanoparticles.

  20. Highly reproducible surface-enhanced Raman scattering-active Au nanostructures prepared by simple electrodeposition: origin of surface-enhanced Raman scattering activity and applications as electrochemical substrates.

    Science.gov (United States)

    Choi, Suhee; Ahn, Miri; Kim, Jongwon

    2013-05-24

    The fabrication of effective surface-enhanced Raman scattering (SERS) substrates has been the subject of intensive research because of their useful applications. In this paper, dendritic gold (Au) rod (DAR) structures prepared by simple one-step electrodeposition in a short time were examined as an effective SERS-active substrate. The SERS activity of the DAR surfaces was compared to that of other nanostructured Au surfaces with different morphologies, and its dependence on the structural variation of DAR structures was examined. These comparisonal investigations revealed that highly faceted sharp edge sites present on the DAR surfaces play a critical role in inducing a high SERS activity. The SERS enhancement factor was estimated to be greater than 10(5), and the detection limit of rhodamine 6G at DAR surfaces was 10(-8)M. The DAR surfaces exhibit excellent spot-to-spot and substrate-to-substrate SERS enhancement reproducibility, and their long-term stability is very good. It was also demonstrated that the DAR surfaces can be effectively utilized in electrochemical SERS systems, wherein a reversible SERS behavior was obtained during the cycling to cathodic potential regions. Considering the straightforward preparation of DAR substrates and the clean nature of SERS-active Au surfaces prepared in the absence of additives, we expect that DAR surfaces can be used as cost-effective SERS substrates in analytical and electrochemical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Surface-enhanced Raman scattering active gold nanoparticle/nanohole arrays fabricated through electron beam lithography

    Science.gov (United States)

    Wu, Tsunghsueh; Lin, Yang-Wei

    2018-03-01

    Effective surface-enhanced Raman scattering (SERS)-active substrates from gold nanoparticle and gold nanohole arrays were successfully fabricated through electron beam lithography with precise computer-aided control of the unit size and intergap distance. Their SERS performance was evaluated using 4-mercaptobenzoic acid (4-MBA). These gold arrays yielded strong SERS signals under 785 nm laser excitation. The enhancement factors for 4-MBA molecules on the prepared gold nanoparticle and nanohole arrays maxed at 1.08 × 107 and 8.61 × 106, respectively. The observed increase in SERS enhancement was attributed to the localized surface plasmon resonance (LSPR) wavelength shifting toward the near-infrared regime when the gold nanohole diameter increased, in agreement with the theoretical prediction in this study. The contribution of LSPR to the Raman enhancement from nanohole arrays deposited on fluorine-doped tin oxide glass was elucidated by comparing SERS and transmission spectra. This simple fabrication procedure, which entails employing electron beam lithography and the controllability of the intergap distance, suggests highly promising uses of nanohole arrays as functional components in sensing and photonic devices.

  2. Sensitive determination of dopamine levels via surface-enhanced Raman scattering of Ag nanoparticle dimers.

    Science.gov (United States)

    Yu, Xiantong; He, XiaoXiao; Yang, Taiqun; Zhao, Litao; Chen, Qichen; Zhang, Sanjun; Chen, Jinquan; Xu, Jianhua

    2018-01-01

    Dopamine (DA) is an important neurotransmitter in the hypothalamus and pituitary gland, which can produce a direct influence on mammals' emotions in midbrain. Additionally, the level of DA is highly related with some important neurologic diseases such as schizophrenia, Parkinson, and Huntington's diseases, etc. In light of the important roles that DA plays in the disease modulation, it is of considerable significance to develop a sensitive and reproducible approach for monitoring DA. The objective of this study was to develop an efficient approach to quantitatively monitor the level of DA using Ag nanoparticle (NP) dimers and enhanced Raman spectroscopy. Ag NP dimers were synthesized for the sensitive detection of DA via surface-enhanced Raman scattering (SERS). Citrate was used as both the capping agent of NPs and sensing agent to DA, which is self-assembled on the surface of Ag NP dimers by reacting with the surface carboxyl group to form a stable amide bond. To improve accuracy and precision, the multiplicative effects model for surface-enhanced Raman spectroscopy was utilized to analyze the SERS assays. A low limits of detection (LOD) of 20 pM and a wide linear response range from 30 pM to 300 nM were obtained for DA quantitative detection. The SERS enhancement factor was theoretically valued at approximately 10 7 by discrete dipole approximation. DA was self-assembled on the citrate capped surface of Ag NPs dimers through the amide bond. The adsorption energy was estimated to be 256 KJ/mol using the Langmuir isotherm model. The density functional theory was used to simulate the spectral characteristics of SERS during the adsorption of DA on the surface of the Ag dimers. Furthermore, to improve the accuracy and precision of quantitative analysis of SERS assays with a multiplicative effects model for surface-enhanced Raman spectroscopy. A LOD of 20 pM DA-level was obtained, and the linear response ranged from 30 pM to 300 nM for quantitative DA detection. The

  3. Structure-selective hot-spot Raman enhancement for direct identification and detection of trace penicilloic acid allergen in penicillin.

    Science.gov (United States)

    Zhang, Liying; Jin, Yang; Mao, Hui; Zheng, Lei; Zhao, Jiawei; Peng, Yan; Du, Shuhu; Zhang, Zhongping

    2014-08-15

    Trace penicilloic acid allergen frequently leads to various fatal immune responses to many patients, but it is still a challenge to directly discriminate and detect its residue in penicillin by a chemosensing way. Here, we report that silver-coated gold nanoparticles (Au@Ag NPs) exhibit a structure-selective hot-spot Raman enhancement capability for direct identification and detection of trace penicilloic acid in penicillin. It has been demonstrated that penicilloic acid can very easily link Au@Ag NPs together by its two carboxyl groups, locating itself spontaneously at the interparticle of Au@Ag NPs to form strong Raman hot-spot. At the critical concentration inducing the nanoparticle aggregation, Raman-enhanced effect of penicilloic acid is ~60,000 folds higher than that of penicillin. In particular, the selective Raman enhancement to the two carboxyl groups makes the peak of carboxyl group at C6 of penicilloic acid appear as a new Raman signal due to the opening of β-lactam ring of penicillin. The surface-enhanced Raman scattering (SERS) nanoparticle sensor reaches a sensitive limit lower than the prescribed 1.0‰ penicilloic acid residue in penicillin. The novel strategy to examine allergen is more rapid, convenient and inexpensive than the conventional separation-based assay methods. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Distinction of gastric cancer tissue based on surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Ma, Jun; Zhou, Hanjing; Gong, Longjing; Liu, Shu; Zhou, Zhenghua; Mao, Weizheng; Zheng, Rong-er

    2012-12-01

    Gastric cancer is one of the most common malignant tumors with high recurrence rate and mortality rate in China. This study aimed to evaluate the diagnostic capability of Surface-enhanced Raman spectroscopy (SERS) based on gold colloids for distinguishing gastric tissues. Gold colloids were directly mixed with the supernatant of homogenized tissues to heighten the Raman signal of various biomolecule. A total of 56 samples were collected from normal (30) and cancer (26). Raman spectra were obtained with a 785nm excitation in the range of 600-1800 cm-1. Significant spectral differences in SERS mainly belong to nucleic acid, proteins and lipids, particularly in the range of 653, 726, 828, 963, 1004, 1032, 1088, 1130, 1243, 1369, 1474, 1596, 1723 cm-1. PCA-LDA algorithms with leave-one-patient-out cross validation yielded diagnostic sensitivities of 90% (27/30), specificities of 88.5% (23/26), and accuracy of 89.3% (50/56), for classification of normal and cancer tissues. The receiver operating characteristic (ROC) surface is 0.917, illustrating the diagnostic utility of SERS together with PCA-LDA to identify gastric cancer from normal tissue. This work demonstrated the SERS techniques can be useful for gastric cancer detection, and it is also a potential technique for accurately identifying cancerous tumor, which is of considerable clinical importance to real-time diagnosis.

  5. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  6. Characterization and noninvasive diagnosis of bladder cancer with serum surface enhanced Raman spectroscopy and genetic algorithms

    Science.gov (United States)

    Li, Shaoxin; Li, Linfang; Zeng, Qiuyao; Zhang, Yanjiao; Guo, Zhouyi; Liu, Zhiming; Jin, Mei; Su, Chengkang; Lin, Lin; Xu, Junfa; Liu, Songhao

    2015-05-01

    This study aims to characterize and classify serum surface-enhanced Raman spectroscopy (SERS) spectra between bladder cancer patients and normal volunteers by genetic algorithms (GAs) combined with linear discriminate analysis (LDA). Two group serum SERS spectra excited with nanoparticles are collected from healthy volunteers (n = 36) and bladder cancer patients (n = 55). Six diagnostic Raman bands in the regions of 481-486, 682-687, 1018-1034, 1313-1323, 1450-1459 and 1582-1587 cm-1 related to proteins, nucleic acids and lipids are picked out with the GAs and LDA. By the diagnostic models built with the identified six Raman bands, the improved diagnostic sensitivity of 90.9% and specificity of 100% were acquired for classifying bladder cancer patients from normal serum SERS spectra. The results are superior to the sensitivity of 74.6% and specificity of 97.2% obtained with principal component analysis by the same serum SERS spectra dataset. Receiver operating characteristic (ROC) curves further confirmed the efficiency of diagnostic algorithm based on GA-LDA technique. This exploratory work demonstrates that the serum SERS associated with GA-LDA technique has enormous potential to characterize and non-invasively detect bladder cancer through peripheral blood.

  7. Synthesis of gold nanostars with fractal structure: application in surface-enhanced Raman scattering

    Science.gov (United States)

    Zhu, Jian; Liu, Mei-Jin; Li, Jian-Jun; Zhao, Jun-Wu

    2017-11-01

    Multi-branched gold nanostars with fractal feature were synthesized using the Triton X-100 participant seed-growth method. By increasing the amount of ascorbic acid, the branch length of gold nanostars could be greatly increased. It has been interesting to find that the secondary growth of new branches takes place from the elementary structure when the aspect ratio of the branches is greater than 8.0 and the corresponding plasmon absorption wavelength is greater than 900 nm. Raman activity of the gold nanostar films has been investigated by using the 4-mercaptobenzoic acid (4-MBA) as Raman active probe. Experimental results show that the surface-enhanced Raman scattering (SERS) ability of the gold nanostars could be efficiently improved when the fractal structure appears. The physical mechanism has been attributed to the intense increased secondary branch number and the increased "hot spots". These unique multi-branched gold nanostars with fractal feature and great SERS activity should have great potential in sensing applications.

  8. Quick detection of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces by surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Huang, Hao; Shi, Hong; Chen, Weiwei; Yu, Yun; Lin, Duo; Xu, Qian; Feng, Shangyuan; Lin, Juqiang; Chen, Rong

    2013-01-01

    A surface-enhanced Raman spectroscopy (SERS) method was developed for the analysis of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces (AMRP) for the first time with the aim to develop a quick method for traditional Chinese medicine detection. Both Raman spectra and SERS spectra were obtained from AMRP, and tentative assignments of the Raman bands in the measured spectra suggested that only a few weak Raman peaks could be observed in the regular Raman spectra, while primary Raman peaks at around 536, 555, 619, 648, 691, 733, 790, 958, 1004, 1031, 1112, 1244, 1324, 1395, 1469, 1574 and 1632 cm −1 could be observed in the SERS spectra, with the strongest signals at 619, 733, 958, 1324, 1395 and 1469 cm −1 . This was due to a strong interaction between the silver colloids and the AMRP, which led to an extraordinary enhancement in the intensity of the Raman scattering in AMRP. This exploratory study suggests the SERS technique has great potential for providing a novel non-destructive method for effectively and accurately detecting traditional Chinese medicine without complicated separation and extraction. (paper)

  9. Quick detection of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces by surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Huang, Hao; Shi, Hong; Feng, Shangyuan; Lin, Juqiang; Chen, Weiwei; Yu, Yun; Lin, Duo; Xu, Qian; Chen, Rong

    2013-01-01

    A surface-enhanced Raman spectroscopy (SERS) method was developed for the analysis of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces (AMRP) for the first time with the aim to develop a quick method for traditional Chinese medicine detection. Both Raman spectra and SERS spectra were obtained from AMRP, and tentative assignments of the Raman bands in the measured spectra suggested that only a few weak Raman peaks could be observed in the regular Raman spectra, while primary Raman peaks at around 536, 555, 619, 648, 691, 733, 790, 958, 1004, 1031, 1112, 1244, 1324, 1395, 1469, 1574 and 1632 cm-1 could be observed in the SERS spectra, with the strongest signals at 619, 733, 958, 1324, 1395 and 1469 cm-1. This was due to a strong interaction between the silver colloids and the AMRP, which led to an extraordinary enhancement in the intensity of the Raman scattering in AMRP. This exploratory study suggests the SERS technique has great potential for providing a novel non-destructive method for effectively and accurately detecting traditional Chinese medicine without complicated separation and extraction.

  10. High-efficiency, 154  W CW, diode-pumped Raman fiber laser with brightness enhancement.

    Science.gov (United States)

    Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Ter-Gabrielyan, Nikolay; Dubinskii, Mark

    2017-01-20

    We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).

  11. One-process fabrication of metal hierarchical nanostructures with rich nanogaps for highly-sensitive surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Liu, Gui-qiang; Yu, Mei-dong; Liu, Zheng-qi; Liu, Xiao-shan; Huang, Shan; Pan, Ping-ping; Wang, Yan; Liu, Mu-lin; Gu, Gang

    2015-01-01

    One-process fabrication of highly active and reproducible surface-enhanced Raman scattering (SERS) substrates via ion beam deposition is reported. The fabricated metal–dielectric–metal (MDM) hierarchical nanostructure possesses rich nanogaps and a tunable resonant cavity. Raman scattering signals of analytes are dramatically strengthened due to the strong near-field coupling of localized surface plasmon resonances (LSPRs) and the strong interaction of LSPRs of metal NPs with surface plasmon polaritons (SPPs) on the underlying metal film by crossing over the dielectric spacer. The maximum Raman enhancement for the highest Raman peak at 1650 cm −1 is 13.5 times greater than that of a single metal nanoparticle (NP) array. Moreover, the SERS activity can be efficiently tailored by varying the size and number of voids between adjacent metal NPs and the thickness of the dielectric spacer. These findings may broaden the scope of SERS applications of MDM hierarchical nanostructures in biomedical and analytical chemistry. (paper)

  12. Faster tissue interface analysis from Raman microscopy images using compressed factorisation

    Science.gov (United States)

    Palmer, Andrew D.; Bannerman, Alistair; Grover, Liam; Styles, Iain B.

    2013-06-01

    The structure of an artificial ligament was examined using Raman microscopy in combination with novel data analysis. Basis approximation and compressed principal component analysis are shown to provide efficient compression of confocal Raman microscopy images, alongside powerful methods for unsupervised analysis. This scheme allows the acceleration of data mining, such as principal component analysis, as they can be performed on the compressed data representation, providing a decrease in the factorisation time of a single image from five minutes to under a second. Using this workflow the interface region between a chemically engineered ligament construct and a bone-mimic anchor was examined. Natural ligament contains a striated interface between the bone and tissue that provides improved mechanical load tolerance, a similar interface was found in the ligament construct.

  13. Imaging phospholipid conformational disorder and packing in giant multilamellar liposome by confocal Raman microspectroscopy

    Science.gov (United States)

    Noothalapati, Hemanth; Iwasaki, Keita; Yoshimoto, Chikako; Yoshikiyo, Keisuke; Nishikawa, Tomoe; Ando, Masahiro; Hamaguchi, Hiro-o.; Yamamoto, Tatsuyuki

    2017-12-01

    Liposomes are closed phospholipid bilayer systems that have profound applications in fundamental cell biology, pharmaceutics and medicine. Depending on the composition (pure or mixture of phospholipids, presence of cholesterol) and preparation protocol, intra- and inter-chain molecular interactions vary leading to changes in the quality (order and packing) of liposomes. So far it is not possible to image conformational disorders and packing densities within a liposome in a straightforward manner. In this study, we utilized confocal Raman microspectroscopy to visualize structural disorders and packing efficiency within a giant multilamellar liposome model by focusing mainly on three regions in the vibrational spectrum (Csbnd C stretching, Csbnd H deformation and Csbnd H stretching). We estimated properties such as trans/gauche isomers and lateral packing probability. Interestingly, our Raman imaging studies revealed gel phase rich domains and heterogeneous lateral packing within the giant multilamellar liposome.

  14. Gold Nanoparticle-based Surface-enhanced Raman Scattering Fe(III) Ion Sensor

    International Nuclear Information System (INIS)

    Ly, Nguyen Hoang; Joo, Sang-Woo; Cho, Kwang Hwi

    2015-01-01

    We performed density functional theory (DFT) calculations of 4-aminobenzo-15-crown-5 (4AB15C5) in conjugation with 4-mercaptobenzoic acid (4MCB) with the polarizable continuum model (PCM) while considering the aqueous media. After specific binding of the ferric ion onto the 4MCB.4AB15C5 compound, the Raman frequencies and intensities were estimated by DFT calculations with the PCM. It was predicted that the Raman intensities became significantly increased upon binding of the ferric ion. 4MCB.4AB15C5 could be assembled on gold nanoparticles (AuNPs) via the cleavage of the thiol bond. Colorimetric and UV.Vis absorption spectroscopy indicated that AuNPs became significantly aggregated in the presence of 1.10 mM of the ferric ion. Surface-enhanced Raman scattering (SERS) of 4MCB.4AB15C5 was used to identify the dissimilar spectral behaviors that yield a difference in intensity in the presence of the ferric ion. These changes were not observed in the other biological ions Zn 2+ , Mn 2+ , Fe 2+ , Na + , K + , Ca 2+ , Mg 2+ , NH 4+ , and Co 2+ . This study indicated that 4AB15C5 could be used to detect ferric ions in aqueous AuNP solutions by a combined method of colorimetric, UV.Vis absorption, and Raman spectroscopy. AuNPs.[4MCB. 4AB15C5] can thus be utilized as a selective turn-on sensor to Fe3 + in aqueous solutions above 1 mM.

  15. Raman Hyperspectral Imaging for Detection of Watermelon Seeds Infected with Acidovorax citrulli

    OpenAIRE

    Lee, Hoonsoo; Kim, Moon S.; Qin, Jianwei; Park, Eunsoo; Song, Yu-Rim; Oh, Chang-Sik; Cho, Byoung-Kwan

    2017-01-01

    The bacterial infection of seeds is one of the most important quality factors affecting yield. Conventional detection methods for bacteria-infected seeds, such as biological, serological, and molecular tests, are not feasible since they require expensive equipment, and furthermore, the testing processes are also time-consuming. In this study, we use the Raman hyperspectral imaging technique to distinguish bacteria-infected seeds from healthy seeds as a rapid, accurate, and non-destructive det...

  16. Detection of Surface-Linked Polychlorinated Biphenyls using Surface-Enhanced Raman Scattering Spectroscopy

    DEFF Research Database (Denmark)

    Rindzevicius, Tomas; Barten, Jan; Vorobiev, Mikhail

    2017-01-01

    We present an improved procedure for analytical detection of toxic polychlorinated biphenyls (PCB) using surface-enhanced Raman scattering (SERS) spectroscopy. A gold-capped silicon nanopillar substrate was utilized to concentrate PCB molecules within an area of high electromagnetic fields through...... formation of microsized nanopillar clusters, and consequently, so-called “hot spots” can be formed. In order to improve PCB detection limit, 3,3',4,4'-tetrachlorobiphenyl (PCB77) compounds were chemically modified with a – SCH3 (PCB77-SCH3) group. Experimental and numerical analysis of vibrational modes...

  17. Surface-enhanced raman spectroscopy substrate for arsenic sensing in groundwater

    Science.gov (United States)

    Yang, Peidong; Mulvihill, Martin; Tao, Andrea R.; Sinsermsuksakul, Prasert; Arnold, John

    2015-06-16

    A surface-enhanced Raman spectroscopy (SERS) substrate formed from a plurality of monolayers of polyhedral silver nanocrystals, wherein at least one of the monolayers has polyvinypyrrolidone (PVP) on its surface, and thereby configured for sensing arsenic is described. Highly active SERS substrates are formed by assembling high density monolayers of differently shaped silver nanocrystals onto a solid support. SERS detection is performed directly on this substrate by placing a droplet of the analyte solution onto the nanocrystal monolayer. Adsorbed polymer, polyvinypyrrolidone (PVP), on the surface of the nanoparticles facilitates the binding of both arsenate and arsenite near the silver surface, allowing for highly accurate and sensitive detection capabilities.

  18. Metal nanostructures for the enhancement of the Raman response of molecular adsorbates

    Science.gov (United States)

    Giorgetti, Emilia; Giammanco, Francesco; Margheri, Giancarlo; Trigari, Silvana; Muniz-Miranda, Maurizio

    2011-08-01

    Spectroscopic investigation of metallic nanostructures of different size and morphology is presented, with particular focus on the capability of enhancing the Raman response of molecular adsorbates, namely on their SERS properties. In this framework, we describe recent results obtained with Au/Ag nanocages and Au nanostars, which can be used conveniently to shift the extinction spectra and the SERS activity up to the near infrared. In the case of nanostars, we present a synthesis procedure which permits fine tuning of their morphology and extinction, thus allowing preparation of structures with controlled SERS activity from 500 up to 1500 nm.

  19. Facile fabrication of microfluidic surface-enhanced Raman scattering devices via lift-up lithography

    Science.gov (United States)

    Wu, Yuanzi; Jiang, Ye; Zheng, Xiaoshan; Jia, Shasha; Zhu, Zhi; Ren, Bin; Ma, Hongwei

    2018-04-01

    We describe a facile and low-cost approach for a flexibly integrated surface-enhanced Raman scattering (SERS) substrate in microfluidic chips. Briefly, a SERS substrate was fabricated by the electrostatic assembling of gold nanoparticles, and shaped into designed patterns by subsequent lift-up soft lithography. The SERS micro-pattern could be further integrated within microfluidic channels conveniently. The resulting microfluidic SERS chip allowed ultrasensitive in situ SERS monitoring from the transparent glass window. With its advantages in simplicity, functionality and cost-effectiveness, this method could be readily expanded into optical microfluidic fabrication for biochemical applications.

  20. In situ surface enhanced resonance Raman scattering analysis of a reactive dye covalently bound to cotton.

    Science.gov (United States)

    White, P C; Munro, C H; Smith, W E

    1996-06-01

    An in situ surface enhanced resonance Raman scattering (SERRS) procedure is described for the analysis of a reactive dye covalently bound to a single strand of a cotton fibre. This procedure can be completed in 5 h, whereas an alternative enzyme digestion method takes approximately 21 h. These two fibre preparation methods give similar spectra from picogram quantities of dye present on a 2-5 mm length of fibre. The in situ nature of the analysis and the small sample size make this method particularly suitable for forensic applications.

  1. Surface-Enhanced Raman Scattering Sensor on an Optical Fiber Probe Fabricated with a Femtosecond Laser

    OpenAIRE

    Ma, Xiaodong; Huo, Haibin; Wang, Wenhui; Tian, Ye; Wu, Nan; Guthy, Charles; Shen, Mengyan; Wang, Xingwei

    2010-01-01

    A novel fabrication method for surface-enhanced Raman scattering (SERS) sensors that used a fast femtosecond (fs) laser scanning process to etch uniform patterns and structures on the endface of a fused silica optical fiber, which is then coated with a thin layer of silver through thermal evaporation is presented. A high quality SERS signal was detected on the patterned surface using a Rhodamine 6G (Rh6G) solution. The uniform SERS sensor built on the tip of the optical fiber tip was small, l...

  2. Surface Enhanced Raman Scattering for Quantification of p-Coumaric Acid Produced by Escherichia coli

    DEFF Research Database (Denmark)

    Morelli, Lidia; Zor, Kinga; Jendresen, Christian Bille

    2017-01-01

    The number of newly developed genetic variants of microbial cell factories for production of biochemicals has been rapidly growing in recent years, leading to an increased need for new screening techniques. We developed a method based on surface-enhanced Raman scattering (SERS) coupled with liquid......-liquid extraction (LLE) for quantification of p-coumaric acid (pHCA) in the supernatant of genetically engineered Escherichia coli (E. coli) cultures. pHCA was measured in a dynamic range from 1 μM up to 50 μM on highly uniform SERS substrates based on leaning gold-capped nanopillars, which showed an in...

  3. Selectivity/Specificity Improvement Strategies in Surface-Enhanced Raman Spectroscopy Analysis

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2017-11-01

    Full Text Available Surface-enhanced Raman spectroscopy (SERS is a powerful technique for the discrimination, identification, and potential quantification of certain compounds/organisms. However, its real application is challenging due to the multiple interference from the complicated detection matrix. Therefore, selective/specific detection is crucial for the real application of SERS technique. We summarize in this review five selective/specific detection techniques (chemical reaction, antibody, aptamer, molecularly imprinted polymers and microfluidics, which can be applied for the rapid and reliable selective/specific detection when coupled with SERS technique.

  4. Recent strategies toward microfluidic-based surface-enhanced Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Týčová, Anna; Přikryl, Jan; Foret, František

    2017-01-01

    Roč. 38, č. 16 (2017), s. 1977-1987 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GBP206/12/G014 Grant - others:AV ČR(CZ) MSM200311601 Program:Program na podporu mezinárodní spolupráce začínajících výzkumných pracovníků Institutional support: RVO:68081715 Keywords : microfluidics * nanoparticles * separation * Surface-enhanced Raman spectroscopy Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 2.744, year: 2016

  5. Rapid identification of bacterial resistance to Ciprofloxacin using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Kastanos, Evdokia; Hadjigeorgiou, Katerina; Pitris, Costas

    2014-02-01

    Due to its effectiveness and broad coverage, Ciprofloxacin is the fifth most prescribed antibiotic in the US. As current methods of infection diagnosis and antibiotic sensitivity testing (i.e. an antibiogram) are very time consuming, physicians prescribe ciprofloxacin before obtaining antibiogram results. In order to avoid increasing resistance to the antibiotic, a method was developed to provide both a rapid diagnosis and the sensitivity to the antibiotic. Using Surface Enhanced Raman Spectroscopy, an antibiogram was obtained after exposing the bacteria to Ciprofloxacin for just two hours. Spectral analysis revealed clear separation between sensitive and resistant bacteria and could also offer some inside into the mechanisms of resistance.

  6. Detection of nerve gases using surface-enhanced Raman scattering substrates with high droplet adhesion

    DEFF Research Database (Denmark)

    Hakonen, Aron; Rindzevicius, Tomas; Schmidt, Michael Stenbæk

    2016-01-01

    Threats from chemical warfare agents, commonly known as nerve gases, constitute a serious security issue of increasing global concern because of surging terrorist activity worldwide. However, nerve gases are difficult to detect using current analytical tools and outside dedicated laboratories. Here...... adhesion and nanopillar clustering due to elasto-capillary forces, resulting in enrichment of target molecules in plasmonic hot-spots with high Raman enhancement. The results may pave the way for strategic life-saving SERS detection of chemical warfare agents in the field....

  7. Surface enhanced Raman spectroscopy analysis of HeLa cells using a multilayer substrate

    Science.gov (United States)

    Aguilar-Hernández, I. A.; Pichardo-Molina, J. L.; Lopez-Luke, T.; Ornelas-Soto, N.

    2017-08-01

    Single cell analysis can provide important information regarding cell composition, and can be used for biomedical applications. In this work, a SERS active substrate formed by 3 layers of gold nanospheres and a final layer of gold nanocubes was used for the label-free SERS analysis of HeLa cells. Nanocubes were selected due to the high electromagnetic enhancement expected in nanoparticles with sharp corners. Significant improvement in the reproducibility and quality of SERS spectra was found when compared to the spectra obtained using a nanosphere-only substrate and normal Raman spectroscopy.

  8. Surface-Enhanced Raman Spectroscopy as a Probe of the Surface Chemistry of Nanostructured Materials.

    Science.gov (United States)

    Dick, Susan; Konrad, Magdalena P; Lee, Wendy W Y; McCabe, Hannah; McCracken, John N; Rahman, Taifur M D; Stewart, Alan; Xu, Yikai; Bell, Steven E J

    2016-07-01

    Surface-enhanced Raman spectroscopy (SERS) is now widely used as a rapid and inexpensive tool for chemical/biochemical analysis. The method can give enormous increases in the intensities of the Raman signals of low-concentration molecular targets if they are adsorbed on suitable enhancing substrates, which are typically composed of nanostructured Ag or Au. However, the features of SERS that allow it to be used as a chemical sensor also mean that it can be used as a powerful probe of the surface chemistry of any nanostructured material that can provide SERS enhancement. This is important because it is the surface chemistry that controls how these materials interact with their local environment and, in real applications, this interaction can be more important than more commonly measured properties such as morphology or plasmonic absorption. Here, the opportunity that this approach to SERS provides is illustrated with examples where the surface chemistry is both characterized and controlled in order to create functional nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Analysis of temporal evolution of quantum dot surface chemistry by surface-enhanced Raman scattering.

    Science.gov (United States)

    Doğan, İlker; Gresback, Ryan; Nozaki, Tomohiro; van de Sanden, Mauritius C M

    2016-07-08

    Temporal evolution of surface chemistry during oxidation of silicon quantum dot (Si-QD) surfaces were probed using surface-enhanced Raman scattering (SERS). A monolayer of hydrogen and chlorine terminated plasma-synthesized Si-QDs were spin-coated on silver oxide thin films. A clearly enhanced signal of surface modes, including Si-Clx and Si-Hx modes were observed from as-synthesized Si-QDs as a result of the plasmonic enhancement of the Raman signal at Si-QD/silver oxide interface. Upon oxidation, a gradual decrease of Si-Clx and Si-Hx modes, and an emergence of Si-Ox and Si-O-Hx modes have been observed. In addition, first, second and third transverse optical modes of Si-QDs were also observed in the SERS spectra, revealing information on the crystalline morphology of Si-QDs. An absence of any of the abovementioned spectral features, but only the first transverse optical mode of Si-QDs from thick Si-QD films validated that the spectral features observed from Si-QDs on silver oxide thin films are originated from the SERS effect. These results indicate that real-time SERS is a powerful diagnostic tool and a novel approach to probe the dynamic surface/interface chemistry of quantum dots, especially when they involve in oxidative, catalytic, and electrochemical surface/interface reactions.

  10. A practical method to fabricate gold substrates for surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Tantra, Ratna; Brown, Richard J C; Milton, Martin J T; Gohil, Dipak

    2008-09-01

    We describe a practical method of fabricating surface-enhanced Raman spectroscopy (SERS) substrates based on dip-coating poly-L-lysine derivatized microscope slides in a gold colloidal suspension. The use of only commercially available starting materials in this preparation is particularly advantageous, aimed at both reducing time and the inconsistency associated with surface modification of substrates. The success of colloid deposition has been demonstrated by scanning electron microscopy (SEM) and the corresponding SERS response (giving performance comparable to the corresponding traditional colloidal SERS substrates). Reproducibility was evaluated by conducting replicate measurements across six different locations on the substrate and assessing the extent of the variability (standard deviation values of spectral parameters: peak width and height), in response to either Rhodamine 6G or Isoniazid. Of particular interest is the observation of how some peaks in a given spectrum are more susceptible to data variability than others. For example, in a Rhodamine 6G SERS spectrum, spectral parameters of the peak at 775 cm(-1) were shown to have a relative standard deviation (RSD) % of or=10%. This observation is best explained by taking into account spectral variations that arise from the effect of a chemisorption process and the local nature of chemical enhancement mechanisms, which affects the enhancement of some spectral peaks but not others (analogous to resonant Raman phenomenon).

  11. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    Science.gov (United States)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  12. Synthesis of anti-aggregation silver nanoparticles based on inositol hexakisphosphoric micelles for a stable surface enhanced Raman scattering substrate

    International Nuclear Information System (INIS)

    Wang Na; Yang Haifeng; Zhu Xuan; Zhang Rui; Wang Yao; Huang Guanfeng; Zhang Zongrang

    2009-01-01

    We report a novel method of synthesizing a kind of silver nanoparticles aided by the inositol hexakisphosphoric micelle as a soft template and stabilizer. By controlling the reaction time, UV-vis and TEM observations of the size growth of the nanoparticles are performed. Careful examinations of surface enhanced Raman scattering (SERS) spectra of 2-mercaptopyridine (2-Mpy) on the as-produced silver nanoparticles exhibit very stable and reproducible Raman signals within about 4 months.

  13. Quick Detection of Contaminants Leaching from Polypropylene Centrifuge Tube with Surface Enhanced Raman Spectroscopy and Ultra Violet Absorption Spectroscopy

    OpenAIRE

    Xu, Zhida; Liu, Logan

    2014-01-01

    Anomalous surface enhanced Raman scattering (SERS) peaks are identified for liquid sample stored in polypropylene centrifuge tubes (PP tube) for months. We observed the unexpected Raman peaks during experiments for Thiamine Hydrochloride aqueous solution stored in PP tube for two months. In order to identify the contaminants we have performed SERS experiments for de-ionized water (DI water) stored in polypropylene centrifuge tube for two months and compared them with fresh DI water sample. We...

  14. Improved surface-enhanced Raman scattering on arrays of gold quasi-3D nanoholes

    KAUST Repository

    Yue, Weisheng

    2012-10-04

    Arrays of gold quasi-3D nanoholes were proposed and fabricated as substrates for surface-enhanced Raman scattering (SERS). By detecting rhodamine 6G (R6G) molecules, the gold quasi-3D nanoholes demonstrated an SERS intensity that was 25-62 times higher than that of two-dimensional nanoholes with the same geometrical shapes and periodicities. The larger SERS enhancement of the quasi-3D nanoholes is attributed to the enhanced electromagnetic field on the top-layer nanohole, the bottom nanodiscs and the field coupling between the two layers. In addition, the investigation of the shape dependence of the SERS on the quasi-3D nanoholes demonstrated that the quadratic, circular, triangular and rhombic holes exhibited different SERS properties. Numerical simulations of the electromagnetic properties on the nanostructures were performed with CST Microwave Studio, and the results agree with the experimental observations. © 2012 IOP Publishing Ltd.

  15. Comparison of Surface-enhanced Raman Scattering Spectra of Two Kinds of Silver Nanoplate Films

    Institute of Scientific and Technical Information of China (English)

    TAO Jin-long; TANG Bin; XU Shu-ping; PAN Ling-yun; XU Wei-qing

    2012-01-01

    Surface-enhanced Raman scattering(SERS) spectra of different silver nanoplate self-assembled films at different excitation wavelengths were fairly compared.Shape conversion from silver nanoprisms to nanodisks on slides was in situ carried out.The SERS spectra of 4-mercaptopyridine(4-MPY) on these anisotropic silver nanoparticle self-assembled films present that strong enhancement appeared when the excitation line and the surface plasmon resonance(SPR) band of silver substrate overlapped.In this model,the influence of the crystal planes of silver nanoplates on SERS enhancement could be ignored because the basal planes were nearly unchanged in two kinds of silver nanoplate self-assembled films.

  16. Silver-coated Si nanograss as highly sensitive surface-enhanced Raman spectroscopy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jing; Kuo, Huei Pei; Hu, Min; Li, Zhiyong; Williams, R.S. [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Ou, Fung Suong [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Rice University, Department of Applied Physics, Houston, TX (United States); Stickle, William F. [Hewlett-Packard Company, Advanced Diagnostic Lab, Corvallis, OR (United States)

    2009-09-15

    We created novel surface-enhanced Raman spectroscopy (SERS) substrates by metalization (Ag) of Si nanograss prepared by a Bosch process which involves deep reactive ion etching of single crystalline silicon. No template or lithography was needed for making the Si nanograss, thus providing a simple and inexpensive method to achieve highly sensitive large-area SERS substrates. The dependence of the SERS effect on the thickness of the metal deposition and on the surface morphology and topology of the substrate prior to metal deposition was studied in order to optimize the SERS signals. We observed that the Ag-coated Si nanograss can achieve uniform SERS enhancement over large area ({proportional_to}1 cm x 1 cm) with an average EF (enhancement factor) of 4.2 x 10{sup 8} for 4-mercaptophenol probe molecules. (orig.)

  17. Development of Raman microspectroscopy for automated detection and imaging of basal cell carcinoma

    Science.gov (United States)

    Larraona-Puy, Marta; Ghita, Adrian; Zoladek, Alina; Perkins, William; Varma, Sandeep; Leach, Iain H.; Koloydenko, Alexey A.; Williams, Hywel; Notingher, Ioan

    2009-09-01

    We investigate the potential of Raman microspectroscopy (RMS) for automated evaluation of excised skin tissue during Mohs micrographic surgery (MMS). The main aim is to develop an automated method for imaging and diagnosis of basal cell carcinoma (BCC) regions. Selected Raman bands responsible for the largest spectral differences between BCC and normal skin regions and linear discriminant analysis (LDA) are used to build a multivariate supervised classification model. The model is based on 329 Raman spectra measured on skin tissue obtained from 20 patients. BCC is discriminated from healthy tissue with 90+/-9% sensitivity and 85+/-9% specificity in a 70% to 30% split cross-validation algorithm. This multivariate model is then applied on tissue sections from new patients to image tumor regions. The RMS images show excellent correlation with the gold standard of histopathology sections, BCC being detected in all positive sections. We demonstrate the potential of RMS as an automated objective method for tumor evaluation during MMS. The replacement of current histopathology during MMS by a ``generalization'' of the proposed technique may improve the feasibility and efficacy of MMS, leading to a wider use according to clinical need.

  18. Simulating Surface-Enhanced Hyper-Raman Scattering Using Atomistic Electrodynamics-Quantum Mechanical Models.

    Science.gov (United States)

    Hu, Zhongwei; Chulhai, Dhabih V; Jensen, Lasse

    2016-12-13

    Surface-enhanced hyper-Raman scattering (SEHRS) is the two-photon analogue of surface-enhanced Raman scattering (SERS), which has proven to be a powerful tool to study molecular structures and surface enhancements. However, few theoretical approaches to SEHRS exist and most neglect the atomistic descriptions of the metal surface and molecular resonance effects. In this work, we present two atomistic electrodynamics-quantum mechanical models to simulate SEHRS. The first is the discrete interaction model/quantum mechanical (DIM/QM) model, which combines an atomistic electrodynamics model of the nanoparticle with a time-dependent density functional theory description of the molecule. The second model is a dressed-tensors method that describes the molecule as a point-dipole and point-quadrupole object interacting with the enhanced local field and field-gradients (FG) from the nanoparticle. In both of these models, the resonance effects are treated efficiently by means of damped quadratic response theory. Using these methods, we simulate SEHRS spectra for benzene and pyridine. Our results show that the FG effects in SEHRS play an important role in determining both the surface selection rules and the enhancements. We find that FG effects are more important in SEHRS than in SERS. We also show that the spectral features of small molecules can be accurately described by accounting for the interactions between the molecule and the local field and FG of the nanoparticle. However, at short distances between the metal and molecule, we find significant differences in the SEHRS enhancements predicted using the DIM/QM and the dressed-tensors methods.

  19. Gabor filter based fingerprint image enhancement

    Science.gov (United States)

    Wang, Jin-Xiang

    2013-03-01

    Fingerprint recognition technology has become the most reliable biometric technology due to its uniqueness and invariance, which has been most convenient and most reliable technique for personal authentication. The development of Automated Fingerprint Identification System is an urgent need for modern information security. Meanwhile, fingerprint preprocessing algorithm of fingerprint recognition technology has played an important part in Automatic Fingerprint Identification System. This article introduces the general steps in the fingerprint recognition technology, namely the image input, preprocessing, feature recognition, and fingerprint image enhancement. As the key to fingerprint identification technology, fingerprint image enhancement affects the accuracy of the system. It focuses on the characteristics of the fingerprint image, Gabor filters algorithm for fingerprint image enhancement, the theoretical basis of Gabor filters, and demonstration of the filter. The enhancement algorithm for fingerprint image is in the windows XP platform with matlab.65 as a development tool for the demonstration. The result shows that the Gabor filter is effective in fingerprint image enhancement technology.

  20. Enhancement of colposcopic image by sulphosalicylic acid.

    Directory of Open Access Journals (Sweden)

    Khilnani P

    1993-01-01

    Full Text Available Acetic acid is used conventionally for enhancement of the colposcopic image. We used sulphosalicylic acid instead of acetic acid in 50 normal cases. The normal appearance was enhanced in all cases. The image was also enhanced in 70% cases of cervical intraepithelial neoplasia and 90% cases of cervical condyloma accuminata. The image was not inferior to that with acetic acid in any of the cases.

  1. Rapid Determination of Thiabendazole Pesticides in Rape by Surface Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Lin, Lei; Dong, Tao; Nie, Pengcheng; Qu, Fangfang; He, Yong; Chu, Bingquan; Xiao, Shupei

    2018-04-04

    Thiabendazole is widely used in sclerotium blight, downy mildew and black rot prevention and treatment in rape. Accurate monitoring of thiabendazole pesticides in plants will prevent potential adverse effects to the Environment and human health. Surface Enhanced Raman Spectroscopy (SERS) is a highly sensitive fingerprint with the advantages of simple operation, convenient portability and high detection efficiency. In this paper, a rapid determination method of thiabendazole pesticides in rape was conducted combining SERS with chemometric methods. The original SERS were pretreated and the partial least squares (PLS) was applied to establish the prediction model between SERS and thiabendazole pesticides in rape. As a result, the SERS enhancing effect based on silver Nano-substrate was better than that of gold Nano-substrate, where the detection limit of thiabendazole pesticides in rape could reach 0.1 mg/L. Moreover, 782, 1007 and 1576 cm −1 could be determined as thiabendazole pesticides Raman characteristic peaks in rape. The prediction effect of thiabendazole pesticides in rape was the best ( R p 2 = 0.94, RMSEP = 3.17 mg/L) after the original spectra preprocessed with 1st-Derivative, and the linear relevance between thiabendazole pesticides concentration and Raman peak intensity at 782 cm −1 was the highest ( R² = 0.91). Furthermore, five rape samples with unknown thiabendazole pesticides concentration were used to verify the accuracy and reliability of this method. It was showed that prediction relative standard deviation was 0.70–9.85%, recovery rate was 94.71–118.92% and t value was −1.489. In conclusion, the thiabendazole pesticides in rape could be rapidly and accurately detected by SERS, which was beneficial to provide a rapid, accurate and reliable scheme for the detection of pesticides residues in agriculture products.

  2. Rapid Determination of Thiabendazole Pesticides in Rape by Surface Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Lei Lin

    2018-04-01

    Full Text Available Thiabendazole is widely used in sclerotium blight, downy mildew and black rot prevention and treatment in rape. Accurate monitoring of thiabendazole pesticides in plants will prevent potential adverse effects to the Environment and human health. Surface Enhanced Raman Spectroscopy (SERS is a highly sensitive fingerprint with the advantages of simple operation, convenient portability and high detection efficiency. In this paper, a rapid determination method of thiabendazole pesticides in rape was conducted combining SERS with chemometric methods. The original SERS were pretreated and the partial least squares (PLS was applied to establish the prediction model between SERS and thiabendazole pesticides in rape. As a result, the SERS enhancing effect based on silver Nano-substrate was better than that of gold Nano-substrate, where the detection limit of thiabendazole pesticides in rape could reach 0.1 mg/L. Moreover, 782, 1007 and 1576 cm−1 could be determined as thiabendazole pesticides Raman characteristic peaks in rape. The prediction effect of thiabendazole pesticides in rape was the best ( R p 2 = 0.94, RMSEP = 3.17 mg/L after the original spectra preprocessed with 1st-Derivative, and the linear relevance between thiabendazole pesticides concentration and Raman peak intensity at 782 cm−1 was the highest (R2 = 0.91. Furthermore, five rape samples with unknown thiabendazole pesticides concentration were used to verify the accuracy and reliability of this method. It was showed that prediction relative standard deviation was 0.70–9.85%, recovery rate was 94.71–118.92% and t value was −1.489. In conclusion, the thiabendazole pesticides in rape could be rapidly and accurately detected by SERS, which was beneficial to provide a rapid, accurate and reliable scheme for the detection of pesticides residues in agriculture products.

  3. Extension of nano-scaled exploration into solution/liquid systems using tip-enhanced Raman scattering

    Science.gov (United States)

    Pienpinijtham, Prompong; Vantasin, Sanpon; Kitahama, Yasutaka; Ekgasit, Sanong; Ozaki, Yukihiro

    2017-08-01

    This review shows updated experimental cases of tip-enhanced Raman scattering (TERS) operated in solution/liquid systems. TERS in solution/liquid is still infancy, but very essential and challenging because crucial and complicated biological processes such as photosynthesis, biological electron transfer, and cellular respiration take place and undergo in water, electrolytes, or buffers. The measurements of dry samples do not reflect real activities in those kinds of systems. To deeply understand them, TERS in solution/liquid is needed to be developed. The first TERS experiment in solution/liquid is successfully performed in 2009. After that time, TERS in solution/liquid has gradually been developed. It shows a potential to study structural changes of biomembranes, opening the world of dynamic living cells. TERS is combined with electrochemical techniques, establishing electrochemical TERS (EC-TERS) in 2015. EC-TERS creates an interesting path to fulfil the knowledge about electrochemical-related reactions or processes. TERS tip can be functionalized with sensitive molecules to act as a "surface-enhanced Raman scattering (SERS) at tip" for investigating distinct properties of systems in solution/liquid e.g., pH and electron transfer mechanism. TERS setup is continuously under developing. Versatile geometry of the setup and a guideline of a systematic implementation for a setup of TERS in solution/liquid are proposed. New style of setup is also reported for TERS imaging in solution/liquid. From all of these, TERS in solution/liquid will expand a nano-scaled exploration into solution/liquid systems of various fields e.g., energy storages, catalysts, electronic devices, medicines, alternative energy sources, and build a next step of nanoscience and nanotechnology.

  4. Synthesis of 2.5 nm colloidal iridium nanoparticles with strong surface enhanced Raman scattering activity

    International Nuclear Information System (INIS)

    Cui, Malin; Zhao, Yuan; Wang, Chan; Song, Qijun

    2016-01-01

    Colloidal iridium nanoparticles (IrNPs) were synthesized through an environmentally friendly approach by using trisodium citrate as the capping molecule in an aqueous medium. The resulting colloidal IrNPs have a typical diameter of 2.5 nm and display absorption bands at 250, 400 and 600 nm. They possess uniform morphology, good dispersibility, excellent stability in water, and exhibit strong surface enhanced Raman scattering (SERS) activity with an enhancement factor (EF) of 3.5 × 10 5 at the 1512 cm -1 peak when using Rhodamine 6G as the probe molecule. The excellent SERS performance of the IrNPs was exemplarily applied to the determination of the industrial colorant Sudan Red I. The peak intensity of the Raman band at 1236 cm -1 is linearly related to the concentration of Sudan Red I which can be determined by SERS in the 2 nM to 8 μM concentration range with a limit of detection as low as 0.6 nM. In our perception, this strong SERS activity of the IrNPs has a large potential in the SERS-based quantitation of various chemical substances. (author)

  5. Implementation of molecularly imprinted polymer beads for surface enhanced Raman detection.

    Science.gov (United States)

    Kamra, Tripta; Zhou, Tongchang; Montelius, Lars; Schnadt, Joachim; Ye, Lei

    2015-01-01

    Molecularly imprinted polymers (MIPs) have a predesigned molecular recognition capability that can be used to build robust chemical sensors. MIP-based chemical sensors allow label-free detection and are particularly interesting due to their simple operation. In this work we report the use of thiol-terminated MIP microspheres to construct surfaces for detection of a model organic analyte, nicotine, by surface enhanced Raman scattering (SERS). The nicotine-imprinted microspheres are synthesized by RAFT precipitation polymerization and converted into thiol-terminated microspheres through aminolysis. The thiol groups on the MIP surface allow the microspheres to be immobilized on a gold-coated substrate. Three different strategies are investigated to achieve surface enhanced Raman scattering in the vicinity of the imprinted sites: (1) direct sputtering of gold nanoparticles, (2) immobilization of gold colloids through the MIP's thiol groups, and (3) trapping of the MIP microspheres in a patterned SERS substrate. For the first time we show that large MIP microspheres can be turned into selective SERS surfaces through the three different approaches of assembly. The MIP-based sensing surfaces are used to detect nicotine to demonstrate the proof of concept. As synthesis and surface functionalization of MIP microspheres and nanoparticles are well established, the methods reported in this work are handy and efficient for constructing label-free chemical sensors, in particular for those based on SERS detection.

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

    Science.gov (United States)

    Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

    2016-06-01

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

  7. Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber

    Science.gov (United States)

    Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.

    2012-03-01

    The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

  8. Surface-enhanced Raman spectroscopy substrate based on Ag-coated self-assembled polystyrene spheres

    Science.gov (United States)

    Mikac, Lara; Ivanda, Mile; Gotić, Marijan; Janicki, Vesna; Zorc, Hrvoje; Janči, Tibor; Vidaček, Sanja

    2017-10-01

    The silver (Ag) films were deposited on the monodispersed polystyrene spheres that were drop-coated on hydrophilic glass substrates in order to form a self-assembled 2D monolayer. Thus prepared Ag films over polystyrene nanospheres (AgFONs) were used to record the surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G (R6G) and pyridine (λex = 514.5 nm). AgFONs were prepared by depositing 120, 180 and 240 nm thick Ag layer on the 1000 nm polystyrene spheres and 80, 120, 160 and 200 nm thick Ag layer on the 350 nm spheres as well as on their mixture (350 + 1000 nm). The silver was deposited by electron beam evaporation technique. The best enhancement of the Raman signal for both test molecules was obtained using 180 nm Ag film deposited on the 1000 nm spheres and using 80 nm Ag film deposited on the 350 nm polystyrene spheres. The lowest detectable concentrations of R6G and pyridine were 10-9 mol L-1 and 1.2 × 10-3 mol L-1, respectively. This study has shown that AgFONs could be regarded as good and reproducible SERS substrate for analytical detection of various organic molecules.

  9. Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

    Science.gov (United States)

    Hippler, Michael

    2015-08-04

    We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

  10. Surface-enhanced Raman scattering active gold nanostructure fabricated by photochemical reaction of synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Akinobu, E-mail: yamaguti@lasti.u-hyogo.ac.jp [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan); Matsumoto, Takeshi [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan); Okada, Ikuo; Sakurai, Ikuya [Synchrotoron Radiation Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Utsumi, Yuichi [Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan)

    2015-06-15

    The deposition of gold nanoparticles in an electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The nanoparticles grew and aggregated into clusters with increasing radiation time. This behavior is explained by evaluating the effect of Derjaguin-Landau-Verweyand-Overbeek (DLVO) interactions combining repulsive electrostatic and attractive van der Waals forces on the particle deposition process. The surface-enhanced Raman scattering (SERS) of 4,4′ -bipyridine (4bpy) in aqueous solution was measured using gold nanoparticles immobilized on silicon substrates under systematically-varied X-ray exposure. The substrates provided an in situ SERS spectrum for 1 nM 4bpy. This demonstration creates new opportunities for chemical and environmental analyses through simple SERS measurements. - Highlights: • Gold nanoparticles were produced by photochemical reaction of synchrotron radiation. • The gold nanoparticles grew and aggregated into the higher-order nanostructure. • The behavior is qualitatively explained by analytical estimation. • The surface-enhanced Raman spectroscopy of 4,4′-bipyridine (4bpy) was demonstrated. • The substrate fabricated in a suitable condition provides in situ SERS for 1 nM 4bpy.

  11. Sub-100 nm gold nanohole-enhanced Raman scattering on flexible PDMS sheets

    Science.gov (United States)

    Lee, Seunghyun; Ongko, Andry; Kim, Ho Young; Yim, Sang-Gu; Jeon, Geumhye; Jeong, Hee Jin; Lee, Seungwoo; Kwak, Minseok; Yang, Seung Yun

    2016-08-01

    Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive vibrational spectroscopy technique enabling detection of multiple analytes at the molecular level in a nondestructive and rapid manner. In this work, we introduce a new approach to fabricate deep subwavelength-scaled (sub-100 nm) metallic nanohole arrays (quasi-3D metallic nanoholes) on flexible and highly efficient SERS substrates. Target structures have been fabricated using a two-step process consisting of (i) direct pattern transfer of spin-coated polymer films onto polydimethylsiloxane (PDMS) substrates by plasma etching with transferred anodic aluminum oxide masks, and (ii) producing SERS-active substrates by functionalization of the etched polymeric films followed by Au deposition. Such an all-dry, top-down lithographic approach enables on-demand patterning of SERS-active metallic nanoholes with high structural fidelity even onto flexible and stretchable substrates, thus making possible multiple sensing modes in a versatile fashion. For example, metallic nanoholes on flexible PDMS substrates are highly amenable to their integration with curved glass sticks, which can be used in optical fiber-integrated SERS systems. Au surfaces immobilized by probe DNA molecules show a selective enhancement of Raman scattering with Cy5-labeled complementary DNA (as compared to flat Au surfaces), demonstrating the potential of using the quasi-3D Au nanohole arrays for bio-sensing applications.

  12. Ag/SiO2 surface-enhanced Raman scattering substrate for plasticizer detection

    Science.gov (United States)

    Wu, Ming-Chung; Lin, Ming-Pin; Lin, Ting-Han; Su, Wei-Fang

    2018-04-01

    In this study, we demonstrated a simple method of fabricating a high-performance surface-enhanced Raman scattering (SERS) substrate. Monodispersive SiO2 colloidal spheres were self-assembled on a silicon wafer, and then a silver layer was coated on it to obtain a Ag/SiO2 SERS substrate. The Ag/SiO2 SERS substrates were used to detect three kinds of plasticizer with different concentrations, namely, including bis(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate (BBP), and dibutyl phthalate (DBP). The enhancement of Raman scattering intensity caused by surface plasmon resonance can be observed using the Ag/SiO2 SERS substrates. The Ag/SiO2 SERS substrate with a 150-nm-thick silver layer can detect plasticizers, and it satisfies the detection limit of plasticizers at 100 ppm. The developed highly sensitive Ag/SiO2 SERS substrates show a potential for the design and fabrication of functional sensors to identify the harmful plasticizers that plastic products release in daily life.

  13. Gold nanoparticles assisted surface enhanced Raman scattering and luminescence of Er{sup 3+} doped zinc–sodium tellurite glass

    Energy Technology Data Exchange (ETDEWEB)

    Ghoshal, S.K.; Awang, Asmahani, E-mail: asmahani_awang@yahoo.com; Sahar, M.R.; Arifin, R.

    2015-03-15

    Significant enhancements in Er{sup 3+} luminescence and Raman intensity mediated via surface plasmon resonance (SPR) of gold (Au) nanoparticles (NPs) embedded zinc–sodium tellurite glass are reported. The observed modifications in the physical and spectroscopic properties are ascribed to the alterations in the glass network. XRD pattern confirms the amorphous nature of prepared glass sample. UV–vis-NIR spectra reveal seven absorption bands. Surface plasmon band is evidenced around 626–630 nm. TEM images manifest the growth of non-spherical Au NPs with average diameter between ∼7.2 nm and 8.6 nm. The visible up-conversion (UC) emission for all samples under 779 nm excitation exhibits three bands centered at 503 nm (green), 546 (green) and 637 nm (red) ascribed to {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2}, {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2} and {sup 4}F{sub 9/2}→{sup 4}I{sub 15/2} transitions. Glass sample with 0.4 mol% Au displaying the highest luminescence intensity with enhancement factor of 3.85 and 3.56 for green bands, and 7.61 for the red band is ascribed to the NPs local field enhancement and energy transfer between rare earth (RE) ions and NPs. FTIR spectra show the vibration of ZnO{sub 4} bonds, Te-O bond in TeO{sub 3} (tp) and TeO{sub 4} (tbp) units and the hydroxyl groups. Raman spectra demonstrate the presence of Er-O and Zn-O bond, anti-symmetric vibrations of Te-O-Te bonds and stretching modes of non-bonded oxygen exists in TeO{sub 3} and TeO{sub 3+1} unit. The amplifications in Raman signals by a factor of 1.62, 1.58, 1.64, 1.68 and 1.69 corresponding to the peak centered at 262 cm{sup −1}, 382 cm{sup −1}, 521 cm{sup −1}, 670 cm{sup −1} and 725 cm{sup −1} are attributed to the contribution of a surface plasmon generating a strong, localized and secondary field. We assert that our glass compositions offer favorable potential to develop solid state lasers and other versatile nanophotonic devices. - Highlights: • Gold

  14. Coherent Raman scattering microscopy for label-free imaging of live amphioxus

    Science.gov (United States)

    Yu, Zhilong; Chen, Tao; Zhang, Xiannian; Shen, Jie; Chen, Junyuan; Huang, Yanyi

    2012-03-01

    The existence of notochord distinguishes chordates from other phyla. Amphioxus is the only animal that keeps notochord during the whole life. Notochord is a unique organ for amphioxus, with its vertically arranged muscular notochordal plates, which is different from notochords in embryos of other chordates. We use stimulated Raman scattering (SRS) microscopy as a non-invasive technique to image the chemical components in amphioxus notochord. SRS provides chemical specificity as spontaneous Raman does and offers a higher sensitivity for fast acquisition. Unlike coherent anti- Stokes Raman scattering (CARS) microscopy, SRS microscopy doesn't have non-resonant background and can better differentiate different components in the specimen. We verify that the notochord is a protein-rich organ, which agrees well with the result of conventional staining methods. Detailed structures in notochordal plates and notochordal sheath are revealed by SRS microscopy with diffraction limited resolution. Our experiment shows that SRS microscopy is an excellent imaging tool for biochemical research with its intrinsic chemical selectivity, high spatiotemporal resolution and native 3D optical sectioning ability.

  15. Characterization of Surface-Enhanced Raman Scattering of Nicotine Utilizing Plasmonic Nanometals for the Applications of Medical and Chemical Sensing

    Science.gov (United States)

    Jackson, Ashley; Rigo, Maria; Seo, Jaetae; HU Team

    2011-05-01

    Raman spectroscopy has received a great deal of interest for its applications in biological sensing and cell imaging due to the ease with which it can be used to extract significant data from tissue and cells. This study has focused on the application of SERS for nicotine detection. Liquid nicotine was diluted and combined with Au nanoparticles (NPs). The nicotine-gold solution was analyzed by acquiring Raman spectra data using a Delta Nu Spectrometer. Absorption data shows the characteristic peak of Au NPs at ~528 nm while showing successful aggregation of the nicotine particles. Data taken from Raman spectra shows characteristic Raman shifts of nicotine at ~1030 cm-1 and ~1590 cm-1. Currently work is being done to optimize the SERS signal for nicotine in the 1590-1600 region using higher concentrations of nicotine and various sizes of Au NPs. This work at Hampton University was supported by the National Science Foundation (HRD-0734635 and HRD-063037).

  16. Multifunctional silver nanoparticle-doped silica for solid-phase extraction and surface-enhanced Raman scattering detection

    Science.gov (United States)

    Markina, Natalia E.; Markin, Alexey V.; Zakharevich, Andrey M.; Gorin, Dmitry A.; Rusanova, Tatiana Yu.; Goryacheva, Irina Yu.

    2016-12-01

    Multifunctional silica gel with embedded silver nanoparticles (SiO2-AgNP) is proposed for application as sorbent for solid-phase extraction (SPE) and simultaneously as substrate for surface-enhanced Raman spectroscopy (SERS) due to their high sorption properties and ability to enhance Raman signal (SERS-active sorbents). SiO2-AgNP was synthesized via alkaline hydrolysis of tetraethyl orthosilicate with simultaneous reduction of silver ions to silver nanoparticles (AgNP) within the SiO2 bulk. Synthesis of AgNP directly to the SiO2 matrix enables to exclude any additional stabilizers for the nanoparticles that educes signal-to-noise ratio during SERS measurement. Apart from Raman spectroscopy, obtained sorbents were also characterized by scanning electron microscopy and UV-visible diffuse reflectance spectroscopy. The influence of AgNO3 concentration used during the SiO2-AgNP synthesis on its gelling time, color, diffuse reflectance spectra, and enhancement of Raman signal was investigated. A Raman enhancement factor of SiO2-AgNP with optimal composition was around 105. Finally, the sorbents were applied for SPE and subsequent SERS detection of model compounds (rhodamine 6G and folic acid). It was found that SPE enables to decrease detectable concentrations by two orders. Therefore, SPE combined with SERS has high potential for further analytical investigations.

  17. Multifunctional silver nanoparticle-doped silica for solid-phase extraction and surface-enhanced Raman scattering detection

    Energy Technology Data Exchange (ETDEWEB)

    Markina, Natalia E.; Markin, Alexey V., E-mail: av-markin@mail.ru; Zakharevich, Andrey M.; Gorin, Dmitry A.; Rusanova, Tatiana Yu.; Goryacheva, Irina Yu. [Saratov State University (Russian Federation)

    2016-12-15

    Multifunctional silica gel with embedded silver nanoparticles (SiO{sub 2}–AgNP) is proposed for application as sorbent for solid-phase extraction (SPE) and simultaneously as substrate for surface-enhanced Raman spectroscopy (SERS) due to their high sorption properties and ability to enhance Raman signal (SERS-active sorbents). SiO{sub 2}–AgNP was synthesized via alkaline hydrolysis of tetraethyl orthosilicate with simultaneous reduction of silver ions to silver nanoparticles (AgNP) within the SiO{sub 2} bulk. Synthesis of AgNP directly to the SiO{sub 2} matrix enables to exclude any additional stabilizers for the nanoparticles that educes signal-to-noise ratio during SERS measurement. Apart from Raman spectroscopy, obtained sorbents were also characterized by scanning electron microscopy and UV-visible diffuse reflectance spectroscopy. The influence of AgNO{sub 3} concentration used during the SiO{sub 2}–AgNP synthesis on its gelling time, color, diffuse reflectance spectra, and enhancement of Raman signal was investigated. A Raman enhancement factor of SiO{sub 2}–AgNP with optimal composition was around 10{sup 5}. Finally, the sorbents were applied for SPE and subsequent SERS detection of model compounds (rhodamine 6G and folic acid). It was found that SPE enables to decrease detectable concentrations by two orders. Therefore, SPE combined with SERS has high potential for further analytical investigations.

  18. Electron-beam lithography of gold nanostructures for surface-enhanced Raman scattering

    KAUST Repository

    Yue, Weisheng

    2012-10-26

    The fabrication of nanostructured substrates with precisely controlled geometries and arrangements plays an important role in studies of surface-enhanced Raman scattering (SERS). Here, we present two processes based on electron-beam lithography to fabricate gold nanostructures for SERS. One process involves making use of metal lift-off and the other involves the use of the plasma etching. These two processes allow the successful fabrication of gold nanostructures with various kinds of geometrical shapes and different periodic arrangements. 4-mercaptopyridine (4-MPy) and Rhodamine 6G (R6G) molecules are used to probe SERS signals on the nanostructures. The SERS investigations on the nanostructured substrates demonstrate that the gold nanostructured substrates have resulted in large SERS enhancement, which is highly dependent on the geometrical shapes and arrangements of the gold nanostructures. © 2012 IOP Publishing Ltd.

  19. Controlled Clustering of Gold Nanoparticles using Solid-support for Surface-enhanced Raman Spectroscopic Probes

    International Nuclear Information System (INIS)

    Chang, Hyejin; Chae, Jinjoo; Jeong, Hong; Kang, Homan; Lee, Yoonsik

    2014-01-01

    We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature

  20. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  1. Rapid, green synthesis and surface-enhanced Raman scattering effect of single-crystal silver nanocubes

    Science.gov (United States)

    Mao, Aiqin; Jin, Xia; Gu, Xiaolong; Wei, Xiaoqing; Yang, Guojing

    2012-08-01

    Single-crystal silver (Ag) nanocubes have been synthesized by a rapid and green method at room temperature by adding sodium hydroxide solution to the mixed solutions of silver nitrate, glucose and polyvinylpyrrolidone (PVP). The X-ray diffraction (XRD), ultraviolet-visible (UV-visible) and transmission electron microscopy (TEM) were used to characterize the phase composition and morphology. The results showed that the as-prepared particles were single-crystal Ag nanocubes with edge lengths of around 77 nm and a growing direction along {1 0 0} facets. As substrates for surface-enhanced Raman scattering (SERS) experiment on crystal violet (CV), the SERS enhancement factor of the as-prepared Ag nanocubes were measured to be 5.5 × 104, indicating potential applications in chemical and biological analysis.

  2. Surface-enhanced Raman spectroscopy for uranium detection and analysis in environmental samples

    International Nuclear Information System (INIS)

    Ruan Chuanmin; Luo Wensui; Wang Wei; Gu Baohua

    2007-01-01

    Techniques for rapid screening of uranium in environmental samples are needed, and this study entails the development of surface-enhanced Raman scattering (SERS) for analyzing uranium in aqueous media with improved sensitivity and reproducibility. A new SERS substrate based on (aminomethyl)phosphonic acid (APA)-modified gold nanoparticles was found to give greater than three orders of magnitude SERS enhancement compared with unmodified bare gold nanoparticles. Intensities of uranyl band at about 830 cm -1 were proportional to the concentrations of uranium in solution, especially at relatively low concentrations ( -5 M). A detection limit of ∼8 x 10 -7 M was achieved with a good reproducibility since the measurement was performed directly in dispersed aqueous suspension. Without pretreatment, the technique was successfully employed for detecting uranium in a highly contaminated groundwater with a low pH, high dissolved salts (e.g., nitrate, sulfate, calcium and aluminum) and total organic carbon

  3. Surface-Enhanced Raman Spectroscopy for Uranium Detection and Analysis in Environmental Samples

    International Nuclear Information System (INIS)

    Ruan, Chuanmin; Luo, Wensui; Wang, Wei; Gu, Baohua

    2007-01-01

    Techniques for rapid screening of uranium in environmental samples are needed, and this study entails the development of surface-enhanced Raman scattering (SERS) for analyzing uranium in aqueous media with improved sensitivity and reproducibility. A new SERS substrate based on (aminomethyl)phosphonic acid (APA)-modified gold nanoparticles was found to give greater than three orders of magnitude SERS enhancement compared with unmodified bare gold nanoparticles. Intensities of uranyl band at about 830 cm-1 were proportional to the concentrations of uranium in solution, especially at relatively low concentrations (<10-5 M). A detection limit of ∼8 e10-7 M was achieved with a good reproducibility since the measurement was performed directly in dispersed aqueous suspension. Without pretreatment, the technique was successfully employed for the detection of uranium in a highly contaminated groundwater with a low pH, high dissolved salts (e.g., nitrate, sulfate, calcium and aluminum) and total organic carbon

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

    Science.gov (United States)

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

    2017-07-01

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

  5. Controlled Clustering of Gold Nanoparticles using Solid-support for Surface-enhanced Raman Spectroscopic Probes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hyejin; Chae, Jinjoo; Jeong, Hong [Department of Chemistry Education, Seoul (Korea, Republic of); Kang, Homan; Lee, Yoonsik [Interdisciplinary Program in Nano-Science and Technology, Pohang (Korea, Republic of)

    2014-03-15

    We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature.

  6. Surface-enhanced Raman scattering and density functional theory study of 1,4-benzenedithiol and its silver complexes.

    Science.gov (United States)

    Shao, Yangfan; Li, Chongyang; Feng, Yuanming; Lin, Wang

    2013-12-01

    This paper experimentally and theoretically investigated Raman and surface-enhanced Raman scattering (SERS) of 1,4-benzenedithiol (1,4-BDT). Density functional theory methods were used to study Raman scattering spectra of isolated 1,4-BDT and 1,4-BDT-Agn (n=2,4,6) complexes with B3LYP/6-311+g(d)(C,H,S)/Lanl2dz(Ag) basis set. A full assignment of the Raman spectrum of 1,4-BDT has been made based on the DFT analysis. The calculated data showed good agreement with experimental observations. The adsorption sites, metal cluster size, and HOMO-LUMO energies are discussed to give insight in the SERS mechanisms for 1,4-BDT molecules. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  8. Multimodal assessment of SERS nanoparticle biodistribution post ingestion reveals new potential for clinical translation of Raman imaging.

    Science.gov (United States)

    Campbell, Jos L; SoRelle, Elliott D; Ilovich, Ohad; Liba, Orly; James, Michelle L; Qiu, Zhen; Perez, Valerie; Chan, Carmel T; de la Zerda, Adam; Zavaleta, Cristina

    2017-08-01

    Despite extensive research and development, new nano-based diagnostic contrast agents have faced major barriers in gaining regulatory approval due to their potential systemic toxicity and prolonged retention in vital organs. Here we use five independent biodistribution techniques to demonstrate that oral ingestion of one such agent, gold-silica Raman nanoparticles, results in complete clearance with no systemic toxicity in living mice. The oral delivery mimics topical administration to the oral cavity and gastrointestinal (GI) tract as an alternative to intravenous injection. Biodistribution and clearance profiles of orally (OR) vs. intravenously (IV) administered Raman nanoparticles were assayed over the course of 48 h. Mice given either an IV or oral dose of Raman nanoparticles radiolabeled with approximately 100 μCi (3.7MBq) of 64 Cu were imaged with dynamic microPET immediately post nanoparticle administration. Static microPET images were also acquired at 2 h, 5 h, 24 h and 48 h. Mice were sacrificed post imaging and various analyses were performed on the excised organs to determine nanoparticle localization. The results from microPET imaging, gamma counting, Raman imaging, ICP-MS, and hyperspectral imaging of tissue sections all correlated to reveal no evidence of systemic distribution of Raman nanoparticles after oral administration and complete clearance from the GI tract within 24 h. Paired with the unique signals and multiplexing potential of Raman nanoparticles, this approach holds great promise for realizing targeted imaging of tumors and dysplastic tissues within the oral cavity and GI-tract. Moreover, these results suggest a viable path for the first translation of high-sensitivity Raman contrast imaging into clinical practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Electromagnetic modelling of Raman enhancement from nanoscale substrates: a route to estimation of the magnitude of the chemical enhancement mechanism in SERS.

    Science.gov (United States)

    Brown, Richard J C; Wang, Jian; Tantra, Ratna; Yardley, Rachel E; Milton, Martin J T

    2006-01-01

    Despite widespread use for more than two decades, the SERS phenomenon has defied accurate physical and chemical explanation. The relative contributions from electronic and chemical mechanisms are difficult to quantify and are often not reproduced under nominally similar experimental conditions. This work has used electromagnetic modelling to predict the Raman enhancement expected from three configurations: metal nanoparticles, structured metal surfaces, and sharp metal tips interacting with metal surfaces. In each case, parameters such as artefact size, artefact separation and incident radiation wavelength have been varied and the resulting electromagnetic field modelled. This has yielded an electromagnetic description of these configurations with predictions of the maximum expected Raman enhancement, and hence a prediction of the optimum substrate configuration for the SERS process. When combined with experimental observations of the dependence of Raman enhancement with changing ionic strength, the modelling results have allowed a novel estimate of the size of the chemical enhancement mechanism to be produced.

  10. Improved molecular fingerprint analysis employing multi-branched gold nanoparticles in conjunction with surface-enhanced Raman scattering

    Directory of Open Access Journals (Sweden)

    Johnston J

    2015-12-01

    Full Text Available Jencilin Johnston,1 Erik N Taylor,1,2 Richard J Gilbert,2 Thomas J Webster1,3 1Department of Chemical Engineering, 2Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA; 3Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: Vibrational spectroscopy is a powerful analytical tool that assesses molecular properties based on spectroscopic signatures. In this study, the effect of gold nanoparticle morphology (spherical vs multi-branched was assessed for the characterization of a Raman signal (ie, molecular fingerprint that may be helpful for numerous medical applications. Multi-branched gold nanoparticles (MBAuNPs were fabricated using a green chemistry method which employed the reduction of gold ion solute by 2-[4-(2-hydroxyethyl-1-piperazyl] ethane sulfonic acid. Two types of reporter dyes, indocyanine (IR820 and IR792 and carbocyanine (DTTC [3,3'-diethylthiatricarbocyanine iodide] and DTDC [3,3'-diethylthiadicarbocyanine iodide], were functionalized to the surface of the MBAuNPs and stabilized with denatured bovine serum albumin, thus forming the surface-enhanced Raman spectroscopy tag. Fluorescein isothiocyanate-conjugated anti-epidermal growth factor receptor to the surface-enhanced Raman spectroscopy tags and the properties of the resulting conjugates were assessed through determination of the Raman signal. Using the MBAuNP Raman probes synthesized in this manner, we demonstrated that MBAuNP provided significantly more surface-enhanced Raman scattering signal when compared with the associated spherical gold nanoparticle of similar size and concentration. MBAuNP enhancements were retained in the surface-enhanced Raman spectroscopy tags complexed to anti-epidermal growth factor receptor, providing evidence that this could be a useful biological probe for enhanced Raman molecular fingerprinting. Furthermore, while utilizing IR820 as a novel reporter dye

  11. Overhauser-enhanced MR imaging (OMRI)

    DEFF Research Database (Denmark)

    Golman, K; Leunbach, I; Ardenkjaer-Larsen, JH

    1998-01-01

    Purpose. To evaluate a new single-electron contrast agent for Overhauser-enhanced MR imaging. The contrast agents that are currently available give enhancement factors that are too low to make the technique a valid option for routine clinical use. Material and Methods. MR images were generated di...

  12. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Sun, Mengtao

    2016-03-01

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.

  13. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yurui [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603-146, Beijing 100190 (China); Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, Göteborg, SE 41296 (Sweden); Zhang, Zhenglong [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603-146, Beijing 100190 (China); School of Physics and Information Technology, Shaanxi Normal University, 710062 Xi’an (China); Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena (Germany); Sun, Mengtao, E-mail: mtsun@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603-146, Beijing 100190 (China)

    2016-03-15

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10{sup −7} Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.

  14. Comparison of time-gated surface-enhanced Raman spectroscopy (TG-SERS) and classical SERS based monitoring of Escherichia coli cultivation samples.

    Science.gov (United States)

    Kögler, Martin; Paul, Andrea; Anane, Emmanuel; Birkholz, Mario; Bunker, Alex; Viitala, Tapani; Maiwald, Michael; Junne, Stefan; Neubauer, Peter

    2018-06-08

    The application of Raman spectroscopy as a monitoring technique for bioprocesses is severely limited by a large background signal originating from fluorescing compounds in the culture media. Here we compare time-gated Raman (TG-Raman)-, continuous wave NIR-process Raman (NIR-Raman) and continuous wave micro-Raman (micro-Raman) approaches in combination with surface enhanced Raman spectroscopy (SERS) for their potential to overcome this limit. For that purpose, we monitored metabolite concentrations of Escherichia coli bioreactor cultivations in cell-free supernatant samples. We investigated concentration transients of glucose, acetate, AMP and cAMP at alternating substrate availability, from deficiency to excess. Raman and SERS signals were compared to off-line metabolite analysis of carbohydrates, carboxylic acids and nucleotides. Results demonstrate that SERS, in almost all cases, led to a higher number of identifiable signals and better resolved spectra. Spectra derived from the TG-Raman were comparable to those of micro-Raman resulting in well-discernable Raman peaks, which allowed for the identification of a higher number of compounds. In contrast, NIR-Raman provided a superior performance for the quantitative evaluation of analytes, both with and without SERS nanoparticles when using multivariate data analysis. This article is protected by copyright. All rights reserved. © 2018 American Institute of Chemical Engineers.

  15. Optical nanoantennas for multiband surface-enhanced infrared and raman spectroscopy

    KAUST Repository

    D'Andrea, Cristiano

    2013-04-23

    In this article we show that linear nanoantennas can be used as shared substrates for surface-enhanced Raman and infrared spectroscopy (SERS and SEIRS, respectively). This is done by engineering the plasmonic properties of the nanoantennas, so to make them resonant in both the visible (transversal resonance) and the infrared (longitudinal resonance), and by rotating the excitation field polarization to selectively take advantage of each resonance and achieve SERS and SEIRS on the same nanoantennas. As a proof of concept, we have fabricated gold nanoantennas by electron beam lithography on calcium difluoride (1-2 μm long, 60 nm wide, 60 nm high) that exhibit a transverse plasmonic resonance in the visible (640 nm) and a particularly strong longitudinal dipolar resonance in the infrared (tunable in the 1280-3100 cm -1 energy range as a function of the length). SERS and SEIRS detection of methylene blue molecules adsorbed on the nanoantenna\\'s surface is accomplished, with signal enhancement factors of 5 × 102 for SERS (electromagnetic enhancement) and up to 105 for SEIRS. Notably, we find that the field enhancement provided by the transverse resonance is sufficient to achieve SERS from single nanoantennas. Furthermore, we show that by properly tuning the nanoantenna length the signals of a multitude of vibrational modes can be enhanced with SEIRS. This simple concept of plasmonic nanosensor is highly suitable for integration on lab-on-a-chip schemes for label-free chemical and biomolecular identification with optimized performances. © 2013 American Chemical Society.

  16. Optical nanoantennas for multiband surface-enhanced infrared and raman spectroscopy

    KAUST Repository

    D'Andrea, Cristiano; Bochterle, Jö rg; Toma, Andrea; Huck, Christian W.; Neubrech, Frank; Messina, Elena; Fazio, Barbara; Maragó , Onofrio M.; Di Fabrizio, Enzo M.; Lamy De La Chapelle, Marc L.; Gucciardi, Pietro Giuseppe; Pucci, Annemarie

    2013-01-01

    In this article we show that linear nanoantennas can be used as shared substrates for surface-enhanced Raman and infrared spectroscopy (SERS and SEIRS, respectively). This is done by engineering the plasmonic properties of the nanoantennas, so to make them resonant in both the visible (transversal resonance) and the infrared (longitudinal resonance), and by rotating the excitation field polarization to selectively take advantage of each resonance and achieve SERS and SEIRS on the same nanoantennas. As a proof of concept, we have fabricated gold nanoantennas by electron beam lithography on calcium difluoride (1-2 μm long, 60 nm wide, 60 nm high) that exhibit a transverse plasmonic resonance in the visible (640 nm) and a particularly strong longitudinal dipolar resonance in the infrared (tunable in the 1280-3100 cm -1 energy range as a function of the length). SERS and SEIRS detection of methylene blue molecules adsorbed on the nanoantenna's surface is accomplished, with signal enhancement factors of 5 × 102 for SERS (electromagnetic enhancement) and up to 105 for SEIRS. Notably, we find that the field enhancement provided by the transverse resonance is sufficient to achieve SERS from single nanoantennas. Furthermore, we show that by properly tuning the nanoantenna length the signals of a multitude of vibrational modes can be enhanced with SEIRS. This simple concept of plasmonic nanosensor is highly suitable for integration on lab-on-a-chip schemes for label-free chemical and biomolecular identification with optimized performances. © 2013 American Chemical Society.

  17. Possibility of 1-nm level localization of a single molecule with gap-mode surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Choi, Han Kyu; Kim, Zee Hwan

    2015-01-01

    The electromagnetic (EM) enhancement mechanism of surface-enhanced Raman scattering (SERS) has been well established through 30 years of extensive investigation: molecules adsorbed on resonantly driven silver or gold nanoparticles (NPs) experience strongly enhanced field and thus show enhanced Raman scattering. Even stronger SERS enhancement is possible with a gap structure in which two or more NPs form assemblies with gap sizes of 1 nm or less. We have theoretically shown that the measurement of SERS angular distribution can reveal the position of a single molecule near the gap with 1-nm accuracy, even though the spatial extent of the enhanced field is ~10 nm. Real implementation of such experiment requires extremely well-defined (preferably a single crystal) dimeric junctions. Nevertheless, the experiment will provide spatial as well as frequency domain information on single-molecule dynamics at metallic surfaces

  18. Surface-enhanced Raman scattering of dipolar molecules by the graphene Fermi surface modulation with different dipole moments

    Science.gov (United States)

    Zhang, Mingjia; Leng, Yandan; Huang, Jing; Yu, JiaoJiao; Lan, Zhenggang; Huang, Changshui

    2017-12-01

    We report the modulation of Raman scattering spectrum of chromophore/graphene hybrids by tunning the molecular polarization with different terminal groups (methyl, methoxy, nitrile, and two nitros). Based on the density functional theory, the specific dipole moment values of the chromophore molecules are calculated. An obvious surface-enhanced Raman scattering (SERS) was observed and the scattering intensity of molecule increases with enlarged dipole moment. According to the analysis of G band Raman shifts of graphene, the enhancement of the Raman signal can be attributed to strong electronic coupling between graphene and chromophore, which is closely related with the modulation of graphene Fermi surface by changing the dipole moment of the molecule. Besides, the optimization of the ground state geometry and the binding energy of the hybrids were also calculated with the Density Functional Based Tight Bonding (DFTB) method, which confirms that the enhanced Raman scattering of molecules on graphene arises from the improved energy level matching between graphene Fermi surface and molecular band, further providing a new way to design novel SERS devices.

  19. Surface-enhanced raman spectroscopy of quinomethionate adsorbed on silver colloids

    International Nuclear Information System (INIS)

    Kim, Mak Soon; Kang, Jae Soo; Park, Si Bum; Lee, Mu Sang

    2003-01-01

    We have studied the surface-enhanced Raman spectroscopy (SERS) spectrum of quinomethionate (6-methyl-1,3-dithiolo(4,5-b)quinoxalin-2-one), which is an insecticide or fungicide used on vegetables and wheat. We observed no signals in the ordinary Raman spectra of solid-state quinomethionate, but when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids prepared by the Creighton et al. method. The influence of pH and the aggregation inductors (Cl - , Br - , I - , F - ) on the adsorption mechanism was investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions: The one N atom or two N atoms are chemisorbed on an Ag surface. An important contribution of the chemical mechanism was inferred when the one N atom was perpendicularly adsorbed on a surface. It is possible that quinomethionate can be detected to about 10 -5 M

  20. Surface enhanced Raman spectroscopic studies on aspirin : An experimental and theoretical approach

    Energy Technology Data Exchange (ETDEWEB)

    Premkumar, R.; Premkumar, S.; Parameswari, A.; Mathavan, T.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, N.M.S.S.V.N College, Madurai-625019, Tamilnadu, India. (India); Rekha, T. N. [PG and Research Department of Physics, Lady Doak College, Madurai-625 002, Tamilnadu, India. (India)

    2016-05-06

    Surface enhanced Raman scattering (SERS) studies on aspirin molecule adsorbed on silver nanoparticles (AgNPs) were investigated by experimental and density functional theory approach. The AgNPs were synthesized by the solution-combustion method and characterized by the X-ray diffraction and high resolution-transmission electron microscopy techniques. The averaged particle size of synthesized AgNPs was calculated as ∼55 nm. The normal Raman spectrum (nRs) and SERS spectrum of the aspirin were recorded. The molecular structure of the aspirin and aspirin adsorbed on silver cluster were optimized by the DFT/ B3PW91 method with LanL2DZ basis set. The vibrational frequencies were calculated and assigned on the basis of potential energy distribution calculation. The calculated nRs and SERS frequencies were correlated well with the observed frequencies. The flat-on orientation was predicted from the nRs and SERS spectra, when the aspirin adsorbed on the AgNPs. Hence, the present studies lead to the understanding of adsorption process of aspirin on the AgNPs, which paves the way for biomedical applications.

  1. High surface enhanced Raman scattering activity of BN nanosheets–Ag nanoparticles hybrids

    International Nuclear Information System (INIS)

    Yang, Shanshan; Zhang, Zhaochun; Zhao, Jun; Zheng, Houli

    2014-01-01

    Highlights: • Boron nitride–silver nanohybrid was acquired through a liquid-phase reducing route. • The composite shown a high-quality SERS activity. • 2-Mercaptobenzimidazole was chemisorbed on silver surface in vertical orientation. -- Abstract: A facile liquid-phase reducing route was developed to modify boron nitride (BN) nanosheets with silver nanoparticles (AgNPs) in order to fabricate BN–AgNPs hybrids with high surface enhanced Raman scattering (SERS) activity. The layered structure and morphology of BN–AgNPs nanohybrids were characterized by transmission electron microscopy and atomic force microscopy, meanwhile, Fourier transform infrared spectroscopy and ultraviolet–visible were used for studying optical properties and surface plasmon resonance applied to the optical sensor. The SERS of adsorbed 2-mercaptobenzimidazole (MBI) molecule was investigated which shown that the BN–AgNPs substrate exhibited a very strong SERS activity, offering a great potential application in molecular probe sensor. On the basis of the analysis of SERS and the Raman surface selection rules, we could draw a conclusion that the MBI molecule was adsorbed upright on the AgNPs surface through the sulphur and nitrogen atoms. What is more, the cyclic voltammetry experiment indicated the electrochemically irreversible behavior of BN–AgNPs nanohybrids in KCl solution

  2. Surface enhanced Raman spectroscopic studies on aspirin : An experimental and theoretical approach

    International Nuclear Information System (INIS)

    Premkumar, R.; Premkumar, S.; Parameswari, A.; Mathavan, T.; Benial, A. Milton Franklin; Rekha, T. N.

    2016-01-01

    Surface enhanced Raman scattering (SERS) studies on aspirin molecule adsorbed on silver nanoparticles (AgNPs) were investigated by experimental and density functional theory approach. The AgNPs were synthesized by the solution-combustion method and characterized by the X-ray diffraction and high resolution-transmission electron microscopy techniques. The averaged particle size of synthesized AgNPs was calculated as ∼55 nm. The normal Raman spectrum (nRs) and SERS spectrum of the aspirin were recorded. The molecular structure of the aspirin and aspirin adsorbed on silver cluster were optimized by the DFT/ B3PW91 method with LanL2DZ basis set. The vibrational frequencies were calculated and assigned on the basis of potential energy distribution calculation. The calculated nRs and SERS frequencies were correlated well with the observed frequencies. The flat-on orientation was predicted from the nRs and SERS spectra, when the aspirin adsorbed on the AgNPs. Hence, the present studies lead to the understanding of adsorption process of aspirin on the AgNPs, which paves the way for biomedical applications.

  3. Monitoring cell culture media degradation using surface enhanced Raman scattering (SERS) spectroscopy.

    Science.gov (United States)

    Calvet, Amandine; Ryder, Alan G

    2014-08-20

    The quality of the cell culture media used in biopharmaceutical manufacturing is a crucial factor affecting bioprocess performance and the quality of the final product. Due to their complex composition these media are inherently unstable, and significant compositional variations can occur particularly when in the prepared liquid state. For example photo-degradation of cell culture media can have adverse effects on cell viability and thus process performance. There is therefore, from quality control, quality assurance and process management view points, an urgent demand for the development of rapid and inexpensive tools for the stability monitoring of these complex mixtures. Spectroscopic methods, based on fluorescence or Raman measurements, have now become viable alternatives to more time-consuming and expensive (on a unit analysis cost) chromatographic and/or mass spectrometry based methods for routine analysis of media. Here we demonstrate the application of surface enhanced Raman scattering (SERS) spectroscopy for the simple, fast, analysis of cell culture media degradation. Once stringent reproducibility controls are implemented, chemometric data analysis methods can then be used to rapidly monitor the compositional changes in chemically defined media. SERS shows clearly that even when media are stored at low temperature (2-8°C) and in the dark, significant chemical changes occur, particularly with regard to cysteine/cystine concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Surface enhanced Raman spectroscopy measurements of MCF7 cells adhesion in confined micro-environments

    KAUST Repository

    De Vitis, Stefania

    2015-05-01

    Undoubtedly cells can perceive the external environment, not only from a biochemical point of view with the related signalling pathways, but also from a physical and topographical perspective. In this sense controlled three dimensional micro-structures as well as patterns at the nano-scale can affect and guide the cell evolution and proliferation, due to the fact that the surrounding environment is no longer isotropic (like the flat surfaces of standard cell culturing) but possesses well defined symmetries and anisotropies. In this work regular arrays of silicon micro-pillars with hexagonal arrangement are used as culturing substrates for MCF-7 breast cancer cells. The characteristic size and spacing of the pillars are tens of microns, comparable with MCF-7 cell dimensions and then well suited to induce acceptable external stimuli. It is shown that these cells strongly modify their morphology for adapting themselves to the micro-structured landscape, by means of protrusions from the main body of the cell. Scanning electron microscopy along with both Raman micro-spectroscopy and surface enhanced Raman spectroscopy are used for topographical and biochemical studies of the new cell arrangement. We have revealed that single MCF-7 cells exploit their capability to produce invadopodia, usually generated to invade the neighboring tissue in metastatic activity, for spanning and growing across separate pillars. © 2015 Elsevier Ltd.

  5. Derivatization reaction-based surface-enhanced Raman scattering (SERS) for detection of trace acetone.

    Science.gov (United States)

    Zheng, Ying; Chen, Zhuo; Zheng, Chengbin; Lee, Yong-Ill; Hou, Xiandeng; Wu, Li; Tian, Yunfei

    2016-08-01

    A facile method was developed for determination of trace volatile acetone by coupling a derivatization reaction to surface-enhanced Raman scattering (SERS). With iodide modified Ag nanoparticles (Ag IMNPs) as the SERS substrate, acetone without obvious Raman signal could be converted to SERS-sensitive species via a chemical derivatization reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH). In addition, acetone can be effectively separated from liquid phase with a purge-sampling device and then any serious interference from sample matrices can be significantly reduced. The optimal conditions for the derivatization reaction and the SERS analysis were investigated in detail, and the selectivity and reproducibility of this method were also evaluated. Under the optimal conditions, the limit of detection (LOD) for acetone was 5mgL(-1) or 0.09mM (3σ). The relative standard deviation (RSD) for 80mgL(-1) acetone (n=9) was 1.7%. This method was successfully used for the determination of acetone in artificial urine and human urine samples with spiked recoveries ranging from 92% to 110%. The present method is convenient, sensitive, selective, reliable and suitable for analysis of trace acetone, and it could have a promising clinical application in early diabetes diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Multifunctional porous silicon nanopillar arrays: antireflection, superhydrophobicity, photoluminescence, and surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Kiraly, Brian; Yang, Shikuan; Huang, Tony Jun

    2013-01-01

    We have fabricated porous silicon nanopillar arrays over large areas with a rapid, simple, and low-cost technique. The porous silicon nanopillars show unique longitudinal features along their entire length and have porosity with dimensions on the single-nanometer scale. Both Raman spectroscopy and photoluminescence data were used to determine the nanocrystallite size to be <3 nm. The porous silicon nanopillar arrays also maintained excellent ensemble properties, reducing reflection nearly fivefold from planar silicon in the visible range without any optimization, and approaching superhydrophobic behavior with increasing aspect ratio, demonstrating contact angles up to 138°. Finally, the porous silicon nanopillar arrays were made into sensitive surface-enhanced Raman scattering (SERS) substrates by depositing metal onto the pillars. The SERS performance of the substrates was demonstrated using a chemical dye Rhodamine 6G. With their multitude of properties (i.e., antireflection, superhydrophobicity, photoluminescence, and sensitive SERS), the porous silicon nanopillar arrays described here can be valuable in applications such as solar harvesting, electrochemical cells, self-cleaning devices, and dynamic biological monitoring. (paper)

  7. Automated image enhancement using power law transformations

    Indian Academy of Sciences (India)

    We propose a scheme for automating power law transformations which are used for image enhancement. The scheme we propose does not require the user to choose the exponent in the power law transformation. This method works well for images having poor contrast, especially to those images in which the peaks ...

  8. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers

    KAUST Repository

    Perozziello, Gerardo; Candeloro, Patrizio; De Grazia, Antonio; Esposito, Francesco; Allione, Marco; Coluccio, Maria Laura; Tallerico, Rossana; Valpapuram, Immanuel; Tirinato, Luca; Das, Gobind; Giugni, Andrea; Torre, Bruno; Veltri, Pierangelo; Kruhne, Ulrich; Della Valle, Giuseppe; Di Fabrizio, Enzo M.

    2015-01-01

    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels- where

  9. Dictionary-enhanced imaging cytometry

    Science.gov (United States)

    Orth, Antony; Schaak, Diane; Schonbrun, Ethan

    2017-02-01

    State-of-the-art high-throughput microscopes are now capable of recording image data at a phenomenal rate, imaging entire microscope slides in minutes. In this paper we investigate how a large image set can be used to perform automated cell classification and denoising. To this end, we acquire an image library consisting of over one quarter-million white blood cell (WBC) nuclei together with CD15/CD16 protein expression for each cell. We show that the WBC nucleus images alone can be used to replicate CD expression-based gating, even in the presence of significant imaging noise. We also demonstrate that accurate estimates of white blood cell images can be recovered from extremely noisy images by comparing with a reference dictionary. This has implications for dose-limited imaging when samples belong to a highly restricted class such as a well-studied cell type. Furthermore, large image libraries may endow microscopes with capabilities beyond their hardware specifications in terms of sensitivity and resolution. We call for researchers to crowd source large image libraries of common cell lines to explore this possibility.

  10. Graphene–Gold Nanoparticles Hybrid—Synthesis, Functionalization, and Application in a Electrochemical and Surface-Enhanced Raman Scattering Biosensor

    Directory of Open Access Journals (Sweden)

    Ibrahim Khalil

    2016-05-01

    Full Text Available Graphene is a single-atom-thick two-dimensional carbon nanosheet with outstanding chemical, electrical, material, optical, and physical properties due to its large surface area, high electron mobility, thermal conductivity, and stability. These extraordinary features of graphene make it a key component for different applications in the biosensing and imaging arena. However, the use of graphene alone is correlated with certain limitations, such as irreversible self-agglomerations, less colloidal stability, poor reliability/repeatability, and non-specificity. The addition of gold nanostructures (AuNS with graphene produces the graphene–AuNS hybrid nanocomposite which minimizes the limitations as well as providing additional synergistic properties, that is, higher effective surface area, catalytic activity, electrical conductivity, water solubility, and biocompatibility. This review focuses on the fundamental features of graphene, the multidimensional synthesis, and multipurpose applications of graphene–Au nanocomposites. The paper highlights the graphene–gold nanoparticle (AuNP as the platform substrate for the fabrication of electrochemical and surface-enhanced Raman scattering (SERS-based biosensors in diverse applications as well as SERS-directed bio-imaging, which is considered as an emerging sector for monitoring stem cell differentiation, and detection and treatment of cancer.

  11. Biological image construction by using Raman radiation and Pca: preliminary results

    International Nuclear Information System (INIS)

    Martinez E, J. C.; Cordova F, T.; Hugo R, V.

    2015-10-01

    Full text: In the last years, the Raman spectroscopy (Rs) technique has had some applications in the study and analysis of biological samples, due to it is able to detect concentrations or presence of certain organic and inorganic compounds of medical interest. In this work, raw data were obtained through measurements in selected points on a square regions in order to detect specific organic / inorganic compounds on biological samples. Gold nano stars samples were prepared and coated with membrane markers (CD 10+ and CD 19+) and diluted in leukemic B lymphocytes. Each data block was evaluated independently by the method of principal component analysis (Pca) in order to find representative dimensionless values (Cp) for each Raman spectrum in a specific coordinate. Each Cp was normalized in a range of 0-255 in order to generate a representative image of 8 bits of the region under study. Data acquisition was performed with Raman microscopy system Renishaw in Via in the range of 550 to 1700 cm-1 with a 785 nm laser source, with a power of 17 m W and 15 s of exposure time were used for each spectrum. In preliminary results could detect the presence of molecular markers CD 10+ and CD 19+ with gold nano stars and discrimination between both markers. The results suggest conducting studies with specific concentrations organic and inorganic materials. (Author)

  12. Biological image construction by using Raman radiation and Pca: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Martinez E, J. C. [IPN, Unidad Profesional Interdisciplinaria de Ingenieria, Campus Guanajuato, Av. Mineral de Valenciana 200, Col. Fracc. Industrial Puerto Interior, 36275 Silao, Guanajuato (Mexico); Cordova F, T. [Universidad de Guanajuato, DIC, Departamento de Ingenieria Fisica, Loma del Bosque No. 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Hugo R, V., E-mail: jcmartineze@ipn.mx [Universidad de Guadalajara, Centro Universitario de Tonala, Morelos No. 180, 69584 Tonala, Jalisco (Mexico)

    2015-10-15

    Full text: In the last years, the Raman spectroscopy (Rs) technique has had some applications in the study and analysis of biological samples, due to it is able to detect concentrations or presence of certain organic and inorganic compounds of medical interest. In this work, raw data were obtained through measurements in selected points on a square regions in order to detect specific organic / inorganic compounds on biological samples. Gold nano stars samples were prepared and coated with membrane markers (CD 10+ and CD 19+) and diluted in leukemic B lymphocytes. Each data block was evaluated independently by the method of principal component analysis (Pca) in order to find representative dimensionless values (Cp) for each Raman spectrum in a specific coordinate. Each Cp was normalized in a range of 0-255 in order to generate a representative image of 8 bits of the region under study. Data acquisition was performed with Raman microscopy system Renishaw in Via in the range of 550 to 1700 cm-1 with a 785 nm laser source, with a power of 17 m W and 15 s of exposure time were used for each spectrum. In preliminary results could detect the presence of molecular markers CD 10+ and CD 19+ with gold nano stars and discrimination between both markers. The results suggest conducting studies with specific concentrations organic and inorganic materials. (Author)

  13. Analysis of low active-pharmaceutical-ingredient signal drugs based on thin layer chromatography and surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Li, Xiao; Chen, Hui; Zhu, Qingxia; Liu, Yan; Lu, Feng

    2016-11-30

    Active pharmaceutical ingredients (API) embedded in the excipients of the formula can usually be unravelled by normal Raman spectroscopy (NRS). However, more and more drugs with low API content and/or low Raman scattering coefficient were insensitive to NRS analysis, which was for the first time defined as Low API-Signal Drugs (LASIDs) in this paper. The NRS spectra of these LASIDs were similar to their dominant excipients' profiles, such as lactose, starch, microcrystalline cellulose (MCC), etc., and were classified into three types as such. 21 out of 100 kinds of drugs were screened as LASIDs and characterized further by Raman microscopic mapping. Accordingly, we proposed a tailored solution to the qualitation and quantitation problem of these LASIDs, using surface-enhanced Raman spectroscopic (SERS) detection on the thin layer chromatographic (TLC) plate both in situ and after-separation. Experimental conditions and parameters including TLC support matrix, SERS substrate, detection mode, similarity threshold, internal standard, etc., were optimized. All LASIDs were satisfactorily identified and the quantitation results agreed well with those of high performance liquid chromatography (HPLC). For some structural analogues of LASIDs, although they presented highly similar SERS spectra and were tough to distinguish even with Raman microscopic mapping, they could be successfully discriminated from each other by coupling SERS (with portable Raman spectrometer) with TLC. These results demonstrated that the proposed solution could be employed to detect the LASIDs with high accuracy and cost-effectiveness. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Silver nanoparticles deposited on anodic aluminum oxide template using magnetron sputtering for surface-enhanced Raman scattering substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wong-ek, Krongkamol [Nanoscience and Technology Program, Chulalongkorn University, Bangkok 10330 (Thailand); Eiamchai, Pitak; Horprathum, Mati; Patthanasettakul, Viyapol [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Limnonthakul, Puenisara [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Chindaudom, Pongpan [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Nuntawong, Noppadon, E-mail: noppadon.nuntawong@nectec.or.t [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand)

    2010-09-30

    Low-cost and highly sensitive surface-enhanced Raman scattering (SERS) substrates have been fabricated by a simple anodizing process and a magnetron sputtering deposition. The substrates, which consist of silver nanoparticles embedded on anodic aluminum oxide (AAO) templates, are investigated by a scanning electron microscope and a confocal Raman spectroscopy. The SERS activities are demonstrated by Raman scattering from adsorbed solutions of methylene blue and pyridine on the SERS substrate surface. The most optimized SERS substrate contains the silver nanoparticles, with a size distribution of 10-30 nm, deposited on the AAO template. From a calculation, the SERS enhancement factor is as high as 8.5 x 10{sup 7}, which suggests strong potentials for direct applications in the chemical detection and analyses.

  15. Spontaneous nano-gap formation in Ag film using NaCl sacrificial layer for Raman enhancement

    Science.gov (United States)

    Min, Kyungchan; Jeon, Wook Jin; Kim, Youngho; Choi, Jae-Young; Yu, Hak Ki

    2018-03-01

    We report the method of fabrication of nano-gaps (known as hot spots) in Ag thin film using a sodium chloride (NaCl) sacrificial layer for Raman enhancement. The Ag thin film (20-50 nm) on the NaCl sacrificial layer undergoes an interfacial reaction due to the AgCl formed at the interface during water molecule intercalation. The intercalated water molecules can dissolve the NaCl molecules at interfaces and form the ionic state of Na+ and Cl-, promoting the AgCl formation. The Ag atoms can migrate by the driving force of this interfacial reaction, resulting in the formation of nano-size gaps in the film. The surface-enhanced Raman scattering activity of Ag films with nano-size gaps has been investigated using Raman reporter molecules, Rhodamine 6G (R6G).

  16. Raman Enhancement and Photo-Bleaching of Organic Dyes in the Presence of Chemical Vapor Deposition-Grown Graphene

    Directory of Open Access Journals (Sweden)

    Jiaxin Weng

    2017-10-01

    Full Text Available Fluorescent organic dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of organic dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chemical vapor deposition (CVD-grown graphene. We show that graphene enhances the Raman signal of a wide range of dyes. The photo-bleaching of the dyes was reduced when the dyes were in contact with graphene. In contrast, monolayer hexagonal boron nitride (h-BN was much less effective in reducing the photo-bleaching rate of the dyes. We attribute the suppression of photo-bleaching to the energy or electron transfer from dye to graphene. The results highlight the potential of CVD graphene as a substrate for protecting and enhancing Raman response of organic dyes.

  17. Rapid Identification of Bacterial Pathogens of Military Interest Using Surface-Enhanced Raman Spectroscopy

    Science.gov (United States)

    2014-06-11

    Failloux, N., Bonnet, 1., Baron, M. H., & Perrier, E. (2003). Quantitative analysis of vitamin A degradation by raman spectroscopy. Applied Spectroscopy...analysis of the Raman-active modes of the anti-tumor agent 6- mercaptopurine . Journal of Raman Spectroscopy, 32(1), 1-8. doi: Doi 10.1002/1097- 4555

  18. Raman enhancement on ultra-clean graphene quantum dots produced by quasi-equilibrium plasma-enhanced chemical vapor deposition.

    Science.gov (United States)

    Liu, Donghua; Chen, Xiaosong; Hu, Yibin; Sun, Tai; Song, Zhibo; Zheng, Yujie; Cao, Yongbin; Cai, Zhi; Cao, Min; Peng, Lan; Huang, Yuli; Du, Lei; Yang, Wuli; Chen, Gang; Wei, Dapeng; Wee, Andrew Thye Shen; Wei, Dacheng

    2018-01-15

    Graphene is regarded as a potential surface-enhanced Raman spectroscopy (SERS) substrate. However, the application of graphene quantum dots (GQDs) has had limited success due to material quality. Here, we develop a quasi-equilibrium plasma-enhanced chemical vapor deposition method to produce high-quality ultra-clean GQDs with sizes down to 2 nm directly on SiO 2 /Si, which are used as SERS substrates. The enhancement factor, which depends on the GQD size, is higher than conventional graphene sheets with sensitivity down to 1 × 10 -9  mol L -1 rhodamine. This is attributed to the high-quality GQDs with atomically clean surfaces and large number of edges, as well as the enhanced charge transfer between molecules and GQDs with appropriate diameters due to the existence of Van Hove singularities in the electronic density of states. This work demonstrates a sensitive SERS substrate, and is valuable for applications of GQDs in graphene-based photonics and optoelectronics.

  19. Gold split-ring resonators (SRRs) as substrates for surface-enhanced raman scattering

    KAUST Repository

    Yue, Weisheng

    2013-10-24

    We used gold split ring resonators (SRRs) as substrates for surface-enhanced Raman scattering (SERS). The arrays of SRRs were fabricated by electron-beam lithography in combination with plasma etching. In the detection of rhodamine 6G (R6G) molecules, SERS enhancement factors of the order of 105 was achieved. This SERS enhancement increased as the size of the split gap decrease as a consequence of the matching between the resonance wavelength of the SRRs and the excitation wavelength of SERS. As the size of the split gap decreased, the localized surface plasmon resonance shifted to near the excitation wavelength and, thus, resulted in the increase in the electric field on the nanostructures. We used finite integration method (FIT) to simulate numerically the electromagnetic properties of the SRRs. The results of the simulation agreed well with our experimental observations. We anticipate this work will provide an approach to manipulate the SERS enhancement by modulating the size of split gap with SRRs without affecting the area and structural arrangement. © 2013 American Chemical Society.

  20. Diameter Effect of Silver Nanorod Arrays to Surface-enhanced Raman Scattering

    International Nuclear Information System (INIS)

    Gu, Geun Hoi; Kim, Min Young; Yoon, Hyeok Jin; Suh, Jung Sang

    2014-01-01

    The effect the diameter of silver nanorod arrays whose distance between the nanorods was uniform at 65 nm have on Surface-enhanced Raman Scattering (SERS) has been studied by varying the diameter from 28 to 51 nm. Nanorod length was fixed at approximately 62 nm, which is the optimum length for SERS by excitation with a 632.8 nm laser line. The transverse and longitudinal modes of the surface plasmon of these silver nanorods were near 400 and 630 nm, respectively. The extinction of the longitudinal mode increased with increasing nanorod diameter, while the transverse mode did not change significantly. High-quality SERS spectra of p-aminothiophenol and benzenethiol adsorbed on the tips of the silver nanorods were observed by excitation with a 632.8 nm laser line. The SERS enhancement increased with increasing nanorod diameter. We concluded that the SERS enhancement increases when the diameter of silver nanorods is increased mainly by increasing the excitation efficiency of the longitudinal mode. The enhancement factor for the silver nanorods with a 51 nm diameter was approximately 2 Χ 10 7

  1. Gold split-ring resonators (SRRs) as substrates for surface-enhanced raman scattering

    KAUST Repository

    Yue, Weisheng; Yang, Yang; Wang, Zhihong; Chen, Longqing; Wang, Xianbin

    2013-01-01

    We used gold split ring resonators (SRRs) as substrates for surface-enhanced Raman scattering (SERS). The arrays of SRRs were fabricated by electron-beam lithography in combination with plasma etching. In the detection of rhodamine 6G (R6G) molecules, SERS enhancement factors of the order of 105 was achieved. This SERS enhancement increased as the size of the split gap decrease as a consequence of the matching between the resonance wavelength of the SRRs and the excitation wavelength of SERS. As the size of the split gap decreased, the localized surface plasmon resonance shifted to near the excitation wavelength and, thus, resulted in the increase in the electric field on the nanostructures. We used finite integration method (FIT) to simulate numerically the electromagnetic properties of the SRRs. The results of the simulation agreed well with our experimental observations. We anticipate this work will provide an approach to manipulate the SERS enhancement by modulating the size of split gap with SRRs without affecting the area and structural arrangement. © 2013 American Chemical Society.

  2. Ex vivo and in vivo coherent Raman imaging of the peripheral and central nervous system

    Science.gov (United States)

    Huff, Terry Brandon

    A hallmark of nervous system disorders is damage or degradation of the myelin sheath. Unraveling the mechanisms underlying myelin degeneration and repair represent one of the great challenges in medicine. This thesis work details the development and utilization of advanced optical imaging methods to gain insight into the structure and function of myelin in both healthy and diseased states in the in vivo environment. This first part of this thesis discusses ex vivo studies of the effects of high-frequency stimulation of spinal tissues on the structure of the node of Ranvier as investigated by coherent anti-Stokes Raman scattering (CARS) imaging (manuscript submitted to Journal of Neurosciece). Reversible paranodal myelin retraction at the nodes of Ranvier was observed during 200 Hz electrical stimulation, beginning minutes after the onset and continuing for up to 10 min after stimulation was ceased. A mechanistic study revealed a Ca2+ dependent pathway: high-frequency stimulation induced paranodal myelin retraction via pathologic calcium influx into axons, calpain activation, and cytoskeleton degradation through spectrin break-down. Also, the construction of dual-scanning CARS microscope for large area mapping of CNS tissues is detailed (Optics Express, 2008, 16:19396-193409). A confocal scanning head equipped with a rotating polygon mirror provides high speed, high resolution imaging and is coupled with a motorized sample stage to generate high-resolution large-area images of mouse brain coronal section and guinea pig spinal cord cross section. The polygon mirror decreases the mosaic acquisition time significantly without reducing the resolution of individual images. The ex vivo studies are then extended to in vivo imaging of mouse sciatic nerve tissue by CARS and second harmonic generation (SHG) imaging (Journal of Microscopy, 2007, 225: 175-182). Following a minimally invasive surgery to open the skin, CARS imaging of myelinated axons and SHG imaging of the

  3. Synthesis of gold nanoflowers using deep eutectic solvent with high surface enhanced Raman scattering properties

    Science.gov (United States)

    Aghakhani Mahyari, Farzaneh; Tohidi, Maryam; Safavi, Afsaneh

    2016-09-01

    A facile, seed-less and one-pot method was developed for synthesis of gold nanoflowers with multiple tips through reduction of HAuCl4 with deep eutectic solvent at room temperature. This solvent is eco-friendly, low-cost, non-toxic and biodegradable and can act as both reducing and shape-controlling agent. In this protocol, highly branched and stable gold nanoflowers were obtained without using any capping agent. The obtained products were characterized by different techniques including, field emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction and UV-vis spectroscopy. The as-prepared gold nanoflowers exhibit efficient surface-enhanced Raman scattering (SERS) properties which can be used as excellent substrates for SERS.

  4. Darkfield microspectroscopy of nanostructures on silver tip-enhanced Raman scattering probes

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Tamitake, E-mail: tamitake-itou@aist.go.jp [Nano-Bioanalysis Team, Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa 761-0395 (Japan); Yamamoto, Yuko S., E-mail: yamayulab@gmail.com [Research Fellow of the Japan Society for the Promotion of Science, Chiyoda, Tokyo 102-8472 (Japan); Department of Chemistry, School of Science and Technology, Kagawa University, Takamatsu, Kagawa 761-0396 (Japan); Suzuki, Toshiaki [UNISOKU Co. Ltd., 2-4-3 Kasugano, Hirakata, Osaka 573-0131 (Japan); Kitahama, Yasutaka; Ozaki, Yukihiro [Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337 (Japan)

    2016-01-11

    We report an evaluation method employing darkfield microspectroscopy for silver probes used in tip-enhanced Raman scattering (TERS). By adjusting the darkfield illumination, the diffracted light from the probe outlines disappears and the diffracted light from the surface nanostructures and tips of the probes appears as colorful spots. Scanning electron microscopy reveals that the spectral variations in these spots reflect the shapes of the surface nanostructures. The tip curvatures correlate to the spectral maxima of their spots. Temporal color changes in the spots indicate the deterioration due to the oxidation of the silver surfaces. These results show that the proposed method is useful for in situ evaluation of plasmonic properties of TERS probes.

  5. Surface-enhanced Raman spectroscopy for differentiation between benign and malignant thyroid tissues

    Science.gov (United States)

    Li, Zuanfang; Li, Chao; Lin, Duo; Huang, Zufang; Pan, Jianji; Chen, Guannan; Lin, Juqiang; Liu, Nenrong; Yu, Yun; Feng, Shangyuan; Chen, Rong

    2014-04-01

    The aim of this study was to evaluate the potential of applying silver nano-particle based surface-enhanced Raman scattering (SERS) to discriminate different types of human thyroid tissues. SERS measurements were performed on three groups of tissue samples including thyroid cancers (n = 32), nodular goiters (n = 20) and normal thyroid tissues (n = 25). Tentative assignments of the measured tissue SERS spectra suggest interesting cancer specific biomolecular differences. The principal component analysis (PCA) and linear discriminate analysis (LDA) together with the leave-one-out, cross-validated technique yielded diagnostic sensitivities of 92%, 75% and 87.5%; and specificities of 82.6%, 89.4% and 84.4%, respectively, for differentiation among normal, nodular and malignant thyroid tissue samples. This work demonstrates that tissue SERS spectroscopy associated with multivariate analysis diagnostic algorithms has great potential for detection of thyroid cancer at the molecular level.

  6. Fast and sensitive trace analysis of malachite green using a surface-enhanced Raman microfluidic sensor.

    Science.gov (United States)

    Lee, Sangyeop; Choi, Junghyun; Chen, Lingxin; Park, Byungchoon; Kyong, Jin Burm; Seong, Gi Hun; Choo, Jaebum; Lee, Yeonjung; Shin, Kyung-Hoon; Lee, Eun Kyu; Joo, Sang-Woo; Lee, Kyeong-Hee

    2007-05-08

    A rapid and highly sensitive trace analysis technique for determining malachite green (MG) in a polydimethylsiloxane (PDMS) microfluidic sensor was investigated using surface-enhanced Raman spectroscopy (SERS). A zigzag-shaped PDMS microfluidic channel was fabricated for efficient mixing between MG analytes and aggregated silver colloids. Under the optimal condition of flow velocity, MG molecules were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower zigzag-shaped PDMS channel. A quantitative analysis of MG was performed based on the measured peak height at 1615 cm(-1) in its SERS spectrum. The limit of detection, using the SERS microfluidic sensor, was found to be below the 1-2 ppb level and this low detection limit is comparable to the result of the LC-Mass detection method. In the present study, we introduce a new conceptual detection technology, using a SERS microfluidic sensor, for the highly sensitive trace analysis of MG in water.

  7. Discrimination of rectal cancer through human serum using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Li, Xiaozhou; Yang, Tianyue; Li, Siqi; Zhang, Su; Jin, Lili

    2015-05-01

    In this paper, surface-enhanced Raman spectroscopy (SERS) was used to detect the changes in blood serum components that accompany rectal cancer. The differences in serum SERS data between rectal cancer patients and healthy controls were examined. Postoperative rectal cancer patients also participated in the comparison to monitor the effects of cancer treatments. The results show that there are significant variations at certain wavenumbers which indicates alteration of corresponding biological substances. Principal component analysis (PCA) and parameters of intensity ratios were used on the original SERS spectra for the extraction of featured variables. These featured variables then underwent linear discriminant analysis (LDA) and classification and regression tree (CART) for the discrimination analysis. Accuracies of 93.5 and 92.4 % were obtained for PCA-LDA and parameter-CART, respectively.

  8. Hollow-Core Photonic Crystal Fibers for Surface-Enhanced Raman Scattering Probes

    Directory of Open Access Journals (Sweden)

    Xuan Yang

    2011-01-01

    Full Text Available Photonic crystal fiber (PCF sensors based on surface-enhanced Raman scattering (SERS have become increasingly attractive in chemical and biological detections due to the molecular specificity, high sensitivity, and flexibility. In this paper, we review the development of PCF SERS sensors with emphasis on our recent work on SERS sensors utilizing hollow-core photonic crystal fibers (HCPCFs. Specifically, we discuss and compare various HCPCF SERS sensors, including the liquid-filled HCPCF and liquid-core photonic crystal fibers (LCPCFs. We experimentally demonstrate and theoretically analyze the high sensitivity of the HCPCF SERS sensors. Various molecules including Rhodamine B, Rhodamine 6G, human insulin, and tryptophan have been tested to show the excellent performance of these fiber sensors.

  9. Cones fabricated by 3D nanoimprint lithography for highly sensitive surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Wu Wei; Hu Min; Ou Fungsuong; Li Zhiyong; Williams, R Stanley

    2010-01-01

    We demonstrated a cost-effective and deterministic method of patterning 3D cone arrays over a large area by using nanoimprint lithography (NIL). Cones with tip radius of less than 10 nm were successfully duplicated onto the UV-curable imprint resist materials from the silicon cone templates. Such cone structures were shown to be a versatile platform for developing reliable, highly sensitive surface enhanced Raman spectroscopy (SERS) substrates. In contrast to the silicon nanocones, the SERS substrates based on the Au coated cones made by the NIL offered significant improvement of the SERS signal. A further improvement of the SERS signal was observed when the polymer cones were imprinted onto a reflective metallic mirror surface. A sub-zeptomole detection sensitivity for a model molecule, trans-1,2-bis(4-pyridyl)-ethylene (BPE), on the Au coated NIL cone surfaces was achieved.

  10. Rapid bacterial antibiotic susceptibility test based on simple surface-enhanced Raman spectroscopic biomarkers

    Science.gov (United States)

    Liu, Chia-Ying; Han, Yin-Yi; Shih, Po-Han; Lian, Wei-Nan; Wang, Huai-Hsien; Lin, Chi-Hung; Hsueh, Po-Ren; Wang, Juen-Kai; Wang, Yuh-Lin

    2016-03-01

    Rapid bacterial antibiotic susceptibility test (AST) and minimum inhibitory concentration (MIC) measurement are important to help reduce the widespread misuse of antibiotics and alleviate the growing drug-resistance problem. We discovered that, when a susceptible strain of Staphylococcus aureus or Escherichia coli is exposed to an antibiotic, the intensity of specific biomarkers in its surface-enhanced Raman scattering (SERS) spectra drops evidently in two hours. The discovery has been exploited for rapid AST and MIC determination of methicillin-susceptible S. aureus and wild-type E. coli as well as clinical isolates. The results obtained by this SERS-AST method were consistent with that by the standard incubation-based method, indicating its high potential to supplement or replace existing time-consuming methods and help mitigate the challenge of drug resistance in clinical microbiology.

  11. Surface enhanced Raman spectroscopy for urinary tract infection diagnosis and antibiogram

    Science.gov (United States)

    Kastanos, Evdokia; Hadjigeorgiou, Katerina; Kyriakides, Alexandros; Pitris, Constantinos

    2010-02-01

    Urinary tract infection diagnosis and antibiogram require a minimum of 48 hours using standard laboratory practice. This long waiting period contributes to an increase in recurrent infections, rising health care costs, and a growing number of bacterial strains developing resistance to antibiotics. In this work, Surface Enhanced Raman Spectroscopy (SERS) was used as a novel method for classifying bacteria and determining their antibiogram. Five species of bacteria were classified with > 90% accuracy using their SERS spectra and a classification algorithm involving novel feature extraction and discriminant analysis. Antibiotic resistance or sensitivity was determined after just a two-hour exposure of bacteria to ciprofloxacin (sensitive) and amoxicillin (resistant) and analysis of their SERS spectra. These results can become the basis for the development of a novel method that would provide same day diagnosis and selection of the most appropriate antibiotic for most effective treatment of a urinary tract infection.

  12. Simultaneous multiplexed quantification of nicotine and its metabolites using surface enhanced Raman scattering.

    Science.gov (United States)

    Alharbi, Omar; Xu, Yun; Goodacre, Royston

    2014-10-07

    The detection and quantification of xenobiotics and their metabolites in man is important for drug dosing, therapy and for substance abuse monitoring where longer-lived metabolic products from illicit materials can be assayed after the drug of abuse has been cleared from the system. Raman spectroscopy offers unique specificity for molecular characterization and this usually weak signal can be significantly enhanced using surface enhanced Raman scattering (SERS). We report here the novel development of SERS with chemometrics for the simultaneous analysis of the drug nicotine and its major xenometabolites cotinine and trans-3'-hydroxycotinine. Initial experiments optimized the SERS conditions and we found that when these three determinands were analysed individually that the maximum SERS signals were found at three different pH. These were pH 3 for nicotine and pH 10 and 11 for cotinine and trans-3'-hydroxycotinine, respectively. Tertiary mixtures containing nicotine, cotinine and trans-3'-hydroxycotinine were generated in the concentration range 10(-7)-10(-5) M and SERS spectra were collected at all three pH values. Chemometric analysis using kernel-partial least squares (K-PLS) and artificial neural networks (ANNs) were conducted and these models were validated using bootstrap resampling. All three analytes were accurately quantified with typical root mean squared error of prediction on the test set data being 5-9%; nicotine was most accurately predicted followed by cotinine and then trans-3'-hydroxycotinine. We believe that SERS is a powerful approach for the simultaneous analysis of multiple determinands without recourse to lengthy chromatography, as demonstrated here for the xenobiotic nicotine and its two major xenometabolites.

  13. Optimal Hotspots of Dynamic Surfaced-Enhanced Raman Spectroscopy for Drugs Quantitative Detection.

    Science.gov (United States)

    Yan, Xiunan; Li, Pan; Zhou, Binbin; Tang, Xianghu; Li, Xiaoyun; Weng, Shizhuang; Yang, Liangbao; Liu, Jinhuai

    2017-05-02

    Surface-enhanced Raman spectroscopy (SERS) as a powerful qualitative analysis method has been widely applied in many fields. However, SERS for quantitative analysis still suffers from several challenges partially because of the absence of stable and credible analytical strategy. Here, we demonstrate that the optimal hotspots created from dynamic surfaced-enhanced Raman spectroscopy (D-SERS) can be used for quantitative SERS measurements. In situ small-angle X-ray scattering was carried out to in situ real-time monitor the formation of the optimal hotspots, where the optimal hotspots with the most efficient hotspots were generated during the monodisperse Au-sol evaporating process. Importantly, the natural evaporation of Au-sol avoids the nanoparticles instability of salt-induced, and formation of ordered three-dimensional hotspots allows SERS detection with excellent reproducibility. Considering SERS signal variability in the D-SERS process, 4-mercaptopyridine (4-mpy) acted as internal standard to validly correct and improve stability as well as reduce fluctuation of signals. The strongest SERS spectra at the optimal hotspots of D-SERS have been extracted to statistics analysis. By using the SERS signal of 4-mpy as a stable internal calibration standard, the relative SERS intensity of target molecules demonstrated a linear response versus the negative logarithm of concentrations at the point of strongest SERS signals, which illustrates the great potential for quantitative analysis. The public drugs 3,4-methylenedioxymethamphetamine and α-methyltryptamine hydrochloride obtained precise analysis with internal standard D-SERS strategy. As a consequence, one has reason to believe our approach is promising to challenge quantitative problems in conventional SERS analysis.

  14. Vibrational imaging of newly synthesized proteins in live cells by stimulated Raman scattering microscopy

    Science.gov (United States)

    Wei, Lu; Yu, Yong; Shen, Yihui; Wang, Meng C.; Min, Wei

    2013-01-01

    Synthesis of new proteins, a key step in the central dogma of molecular biology, has been a major biological process by which cells respond rapidly to environmental cues in both physiological and pathological conditions. However, the selective visualization of a newly synthesized proteome in living systems with subcellular resolution has proven to be rather challenging, despite the extensive efforts along the lines of fluorescence staining, autoradiography, and mass spectrometry. Herein, we report an imaging technique to visualize nascent proteins by harnessing the emerging stimulated Raman scattering (SRS) microscopy coupled with metabolic incorporation of deuterium-labeled amino acids. As a first demonstration, we imaged newly synthesized proteins in live mammalian cells with high spatial–temporal resolution without fixation or staining. Subcellular compartments with fast protein turnover in HeLa and HEK293T cells, and newly grown neurites in differentiating neuron-like N2A cells, are clearly identified via this imaging technique. Technically, incorporation of deuterium-labeled amino acids is minimally perturbative to live cells, whereas SRS imaging of exogenous carbon–deuterium bonds (C–D) in the cell-silent Raman region is highly sensitive, specific, and compatible with living systems. Moreover, coupled with label-free SRS imaging of the total proteome, our method can readily generate spatial maps of the quantitative ratio between new and total proteomes. Thus, this technique of nonlinear vibrational imaging of stable isotope incorporation will be a valuable tool to advance our understanding of the complex spatial and temporal dynamics of newly synthesized proteome in vivo. PMID:23798434

  15. Diffraction enhanced x-ray imaging

    International Nuclear Information System (INIS)

    Thomlinson, W.; Zhong, Z.; Johnston, R.E.; Sayers, D.

    1997-09-01

    Diffraction enhanced imaging (DEI) is a new x-ray radiographic imaging modality using synchrotron x-rays which produces images of thick absorbing objects that are almost completely free of scatter. They show dramatically improved contrast over standard imaging applied to the same phantoms. The contrast is based not only on attenuation but also the refraction and diffraction properties of the sample. The diffraction component and the apparent absorption component (absorption plus extinction contrast) can each be determined independently. This imaging method may improve the image quality for medical applications such as mammography

  16. Long reach and enhanced power budget DWDM radio-over-fibre link supported by Raman amplification and coherent detection

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil; Fernandez, Amaya

    2009-01-01

    We report on a scalable and enhanced power budget radio-over-fibre system for hybrid-wireless access networks operating at 12.5 GHz DWDM spacing for 5 GHz RF carriers over a 60 km fibre link with Raman amplification....

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

    Czech Academy of Sciences Publication Activity Database

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

    2014-01-01

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

  18. Detection of bacterial metabolites through dynamic acquisition from surface enhanced raman spectroscopy substrates integtrated in a centrifugal microfluidic platform

    DEFF Research Database (Denmark)

    Durucan, Onur; Morelli, Lidia; Schmidt, Michael Stenbæk

    2015-01-01

    In this work we present a novel technology that combines the advantages of centrifugal microfluidics with dynamic in-situ Surface Enhanced Raman Spectroscopy (SERS) sensing. Our technology is based on an automated readout system that allows on-line SERS acquisition on a rotating centrifugal...

  19. Surface-Enhanced Resonance Raman Scattering and Visible Extinction Spectroscopy of Copper Chlorophyllin: An Upper Level Chemistry Experiment

    Science.gov (United States)

    Schnitzer, Cheryl S.; Reim, Candace Lawson; Sirois, John J.; House, Paul G.

    2010-01-01

    Advanced chemistry students are introduced to surface-enhanced resonance Raman scattering (SERRS) by studying how sodium copper chlorophyllin (CuChl) adsorbs onto silver colloids (CuChl/Ag) as a function of pH. Using both SERRS and visible extinction spectroscopy, the extent of CuChl adsorption and colloidal aggregation are monitored. Initially at…

  20. Label-Free Detection of Glycan-Protein Interactions for Array Development by Surface-Enhanced Raman Spectroscopy (SERS)

    NARCIS (Netherlands)

    Li, Xiuru; Martin, Sharon J H; Chinoy, Zoeisha S; Liu, Lin; Rittgers, Brandon; Dluhy, Richard A; Boons, Geert-Jan

    2016-01-01

    A glyco-array platform has been developed, in which glycans are attached to plasmonic nanoparticles through strain-promoted azide-alkyne cycloaddition. Glycan-protein binding events can then be detected in a label-free manner employing surface-enhanced Raman spectroscopy (SERS). As proof of concept,

  1. Surface-enhanced Raman scattering (SERS)-based volatile organic compounds (VOCs) detection using plasmonic bimetallic nanogap substrate

    DEFF Research Database (Denmark)

    Wong, Chi Lok; Dinish, U. S.; Buddharaju, Kavitha Devi

    2014-01-01

    In this paper, we present surface-enhanced Raman scattering (SERS)-based volatile organic compounds (VOCs) detection with bimetallic nanogap structure substrate. Deep UV photolithography at the wavelength of 250 nm is used to pattern circular shape nanostructures. The nanogap between adjacent cir......-based VOCs detection platform for point-of-care breath analysis, homeland security, chemical sensing and environmental monitoring....

  2. Origin of enhancement in Raman scattering from Ag-dressed carbon-nanotube antennas : experiment and modelling

    NARCIS (Netherlands)

    Raziman, T.V.; Duenas, J.A.; Milne, W.I.; Martin, O.J.F.; Dawson, P.

    2018-01-01

    The D- and G-band Raman signals from random arrays of vertically aligned, multi-walled carbon nanotubes are significantly enhanced (up to ∼14×) while the signal from the underlying Si substrate is simultaneously attenuated (up to ∼6×) when the nanotubes are dressed, either capped or coated, with Ag.

  3. The nature of chemisorbates formed from ammonia on gold and palladium electrodes as discerned from surface-enhanced Raman spectroscopy

    NARCIS (Netherlands)

    Vooys, de A.C.A.; Mrozek, M.F.; Koper, M.T.M.; Santen, van R.A.; Veen, van J.A.R.; Weaver, M.J.

    2001-01-01

    The chemisorbates formed from ammonia-containing alkaline electrolyte on gold and palladium electrodes have been identified using surface-enhanced Raman spectroscopy (SERS). On gold, a potential-dependent band at ca. 365-385 cm(-1) is observed, consistent with the metal-nitrogen stretch for

  4. Achieving Very Low Levels of Detection: An Improved Surface-Enhanced Raman Scattering Experiment for the Physical Chemistry Teaching Laboratory

    Science.gov (United States)

    McMillan, Brian G.

    2016-01-01

    This experiment was designed and successfully introduced to complement the nanochemistry taught to undergraduate students in a useful and interesting way. Colloidal Ag nanoparticles were synthesized by a simple, room-temperature method, and the resulting suspension was then used to study the surface-enhanced Raman scattering (SERS) of methylene…

  5. In situ identification of high-performance thin-layer chromatography spots by fourier transform surface-enhanced Raman scattering

    Science.gov (United States)

    Koglin, Eckhardt; Kramer, Hella; Sawatski, Juergen; Lehner, Carolin; Hellman, Janice L.

    1994-01-01

    FT-SERS has been used to identify samples supported on high-performance thin-layer chromatography plates. The TLC plates were sprayed with colloidal silver solutions which resulted in enhancement of the FT-Raman scattering of these biologically and environmentally important compounds.

  6. Application of silver films with different roughness parameter for septic human serum albumin detection by Surface Enhanced Raman Spectroscopy

    Science.gov (United States)

    Zyubin, A. Y.; Konstantinova, E. I.; Matveeva, K. I.; Slezhkin, V. A.; Samusev, I. G.; Demin, M. V.; Bryukhanov, V. V.

    2018-01-01

    In this paper, the rough silver films parameters investigation, used as media for surface enhancement Raman spectroscopy for health and septic human serum albumin (HSA) study results have been presented. The detection of small concentrations of HSA isolated from blood serum and it main vibrational groups identification has been done.

  7. An enhanced fractal image denoising algorithm

    International Nuclear Information System (INIS)

    Lu Jian; Ye Zhongxing; Zou Yuru; Ye Ruisong

    2008-01-01

    In recent years, there has been a significant development in image denoising using fractal-based method. This paper presents an enhanced fractal predictive denoising algorithm for denoising the images corrupted by an additive white Gaussian noise (AWGN) by using quadratic gray-level function. Meanwhile, a quantization method for the fractal gray-level coefficients of the quadratic function is proposed to strictly guarantee the contractivity requirement of the enhanced fractal coding, and in terms of the quality of the fractal representation measured by PSNR, the enhanced fractal image coding using quadratic gray-level function generally performs better than the standard fractal coding using linear gray-level function. Based on this enhanced fractal coding, the enhanced fractal image denoising is implemented by estimating the fractal gray-level coefficients of the quadratic function of the noiseless image from its noisy observation. Experimental results show that, compared with other standard fractal-based image denoising schemes using linear gray-level function, the enhanced fractal denoising algorithm can improve the quality of the restored image efficiently

  8. Tip-Selective Growth of Silver on Gold Nanostars for Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Zhang, Weiqing; Liu, Jie; Niu, Wenxin; Yan, Heng; Lu, Xianmao; Liu, Bin

    2018-04-19

    Nanogaps as "hot spots" with highly localized surface plasmon can generate ultrastrong electromagnetic fields. Superior to the exterior nanogaps obtained via aggregation and self-assembly, interior nanogaps within Au and Ag nanostructures give stable and reproducible surface-enhanced Raman scattering (SERS) signals. However, the synthesis of nanostructures with interior hot spots is still challenging because of the lack of high-yield strategies and clear design principles. Herein, gold-silver nanoclusters (Au-Ag NCs) with multiple interior hot spots were fabricated as SERS platforms via selective growth of Ag nanoparticles on the tips of Au nanostars (Au NSs). Furthermore, the interior gap sizes of Au-Ag NCs can be facilely tuned by changing the amount of AgNO 3 used. Upon 785 nm excitation, single Au-Ag NC 350 exhibits 43-fold larger SERS enhancement factor and the optimal signal reproducibility relative to single Au NS. The SERS enhancement factors and signal reproducibility of Au-Ag NCs increase with the decrease of gap sizes. Collectively, the Au-Ag NCs could serve as a flexible, reproducible, and active platform for SERS investigation.

  9. Sensitive Detection of Biomolecules by Surface Enhanced Raman Scattering using Plant Leaves as Natural Substrates

    Directory of Open Access Journals (Sweden)

    Sharma Vipul

    2017-01-01

    Full Text Available Detection of biomolecules is highly important for biomedical and other biological applications. Although several methods exist for the detection of biomolecules, surface enhanced Raman scattering (SERS has a unique role in greatly enhancing the sensitivity. In this work, we have demonstrated the use of natural plant leaves as facile, low cost and eco-friendly SERS substrates for the sensitive detection of biomolecules. Specifically, we have investigated the influence of surface topography of five different plant leaf based substrates, deposited with Au, on the SERS performance by using L-cysteine as a model biomolecule. In addition, we have also compared the effect of sputter deposition of Au thin film with dropcast deposition of Au nanoparticles on the leaf substrates. Our results indicate that L-cysteine could be detected with high sensitivity using these plant leaf based substrates and the leaf possessing hierarchical micro/nanostructures on its surface shows higher SERS enhancement compared to a leaf having a nearplanar surface. Furthermore, leaves with drop-casted Au nanoparticle clusters performed better than the leaves sputter deposited with a thin Au film.

  10. Plasmonic Heterodimers with Binding Site-Dependent Hot Spot for Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Tian, Yuanyuan; Shuai, Zhenhua; Shen, Jingjing; Zhang, Lei; Chen, Shufen; Song, Chunyuan; Zhao, Baomin; Fan, Quli; Wang, Lianhui

    2018-05-07

    A novel plasmonic heterodimer nanostructure with a controllable self-assembled hot spot is fabricated by the conjugation of individual Au@Ag core-shell nanocubes (Au@Ag NCs) and varisized gold nanospheres (GNSs) via the biotin-streptavidin interaction from the ensemble to the single-assembly level. Due to their featured configurations, three types of heterogeneous nanostructures referred to as Vertice, Vicinity, and Middle are proposed and a single hot spot forms between the nanocube and nanosphere, which exhibits distinct diversity in surface plasmon resonance effect. Herein, the calculated surface-enhanced Raman scattering enhancement factors of the three types of heterodimers show a narrow distribution and can be tuned in orders of magnitude by controlling the size of GNSs onto individual Au@Ag NCs. Particularly, the Vertice heterodimer with unique configuration can provide extraordinary enhancement of the electric field for the single hot spot region due to the collaborative interaction of lightning rod effect and interparticle plasmon coupling effect. This established relationship between the architecture and the corresponding optical properties of the heterodimers provides the basis for creating controllable platforms which can be exploited in the applications of plasmonic devices, electronics, and biodetection. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Design, fabrication, and characterization of metallic nanostructures for surface-enhanced Raman spectroscopy and plasmonic applications

    Science.gov (United States)

    Hao, Qingzhen

    Metal/dielectric nanostructures have the ability to sustain coherent electron oscillations known as surface plasmons. Due to their capability of localizing and guiding light in sub-wavelength metal nanostructures beyond diffraction limits, surface plasmon-based photonics, or “plasmonics” has opened new physical phenomena and lead to novel applications in metamaterials, optoelectronics, surface enhanced spectroscopy and biological sensing. This dissertation centers on design, fabrication, characterization of metallic nanostructures and their applications in surface-enhanced Raman spectroscopy (SERS) and actively tunable plasmonics. Metal-dielectric nanostructures are the building blocks for photonic metamaterials. One valuable design guideline for metamaterials is the Babinet’s principle, which governs the optical properties of complementary nanostructures. However, most complementary metamaterials are designed for the far infrared region or beyond, where the optical absorption of metal is small. We have developed a novel dual fabrication method, capable of simultaneously producing optically thin complementary structures. From experimental measurements and theoretical simulations, we showed that Babinet’s principle qualitatively holds in the visible region for the optically thin complements. The complementary structure is also a good platform to study subtle differences between nanoparticles and nanoholes in SERS (a surface sensitive technique, which can enhance the conventional Raman cross-section by 106˜108 fold, thus very useful for highly sensitive biochemical sensing). Through experimental measurement and theoretical analysis, we showed that the SERS enhancement spectrum (plot of SERS enhancement versus excitation wavelengths), dominated by local near-field, for nanoholes closely follows their far-field optical transmission spectrum. However, the enhancement spectrum for nanoparticles red-shifts significantly from their far-field optical extinction

  12. Surface-enhanced Raman scattering of 4-aminobenzenethiol sandwiched between silver nanoparticles and gold micro-powders

    International Nuclear Information System (INIS)

    Choi, Jeong Yong; Lee, Hyang Bong; Kim, Kwan; Shin Kuan Soo

    2015-01-01

    The surface-enhanced Raman scattering (SERS) activity of micrometer-sized gold (μAu) powders is far weaker than that of micrometer-sized silver (μAg) powders. The Raman peaks of organics assembled on μAu powders can, however, be enhanced dramatically by depositing Ag nanoparticles thereon to form the so-called sandwich structures. This is demonstrated in this work by using 4-aminobenzenthiol (4-ABT) as the prototype organic. Besides, the b_2-type bands of 4-ABT are found to be enhanced more than the a1-type band, and this is presumed to be a result of the favorable Ag-to-Au charge transfer configuration of the sandwich structure (Ag/4-ABT/μAu), associated with the chemical enhancement mechanism in SERS

  13. Surface-Enhanced Raman Scattering (SERS) for Detection in Immunoassays: applications, fundamentals, and optimization

    International Nuclear Information System (INIS)

    Jeremy Daniel Driskell

    2006-01-01

    Immunoassays have been utilized for the detection of biological analytes for several decades. Many formats and detection strategies have been explored, each having unique advantages and disadvantages. More recently, surface-enhanced Raman scattering (SERS) has been introduced as a readout method for immunoassays, and has shown great potential to meet many key analytical figures of merit. This technology is in its infancy and this dissertation explores the diversity of this method as well as the mechanism responsible for surface enhancement. Approaches to reduce assay times are also investigated. Implementing the knowledge gained from these studies will lead to a more sensitive immunoassay requiring less time than its predecessors. This dissertation is organized into six sections. The first section includes a literature review of the previous work that led to this dissertation. A general overview of the different approaches to immunoassays is given, outlining the strengths and weaknesses of each. Included is a detailed review of binding kinetics, which is central for decreasing assay times. Next, the theoretical underpinnings of SERS is reviewed at its current level of understanding. Past work has argued that surface plasmon resonance (SPR) of the enhancing substrate influences the SERS signal; therefore, the SPR of the extrinsic Raman labels (ERLs) utilized in our SERS-based immunoassay is discussed. Four original research chapters follow the Introduction, each presented as separate manuscripts. Chapter 2 modifies a SERS-based immunoassay previously developed in our group, extending it to the low-level detection of viral pathogens and demonstrating its versatility in terms of analyte type, Chapter 3 investigates the influence of ERL size, material composition, and separation distance between the ERLs and capture substrate on the SERS signal. This chapter links SPR with SERS enhancement factors and is consistent with many of the results from theoretical treatments

  14. Surface-Enhanced Raman Scattering (SERS) for Detection in Immunoassays. Applications, fundamentals, and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Driskell, Jeremy Daniel [Iowa State Univ., Ames, IA (United States)

    2006-08-09

    Immunoassays have been utilized for the detection of biological analytes for several decades. Many formats and detection strategies have been explored, each having unique advantages and disadvantages. More recently, surface-enhanced Raman scattering (SERS) has been introduced as a readout method for immunoassays, and has shown great potential to meet many key analytical figures of merit. This technology is in its infancy and this dissertation explores the diversity of this method as well as the mechanism responsible for surface enhancement. Approaches to reduce assay times are also investigated. Implementing the knowledge gained from these studies will lead to a more sensitive immunoassay requiring less time than its predecessors. This dissertation is organized into six sections. The first section includes a literature review of the previous work that led to this dissertation. A general overview of the different approaches to immunoassays is given, outlining the strengths and weaknesses of each. Included is a detailed review of binding kinetics, which is central for decreasing assay times. Next, the theoretical underpinnings of SERS is reviewed at its current level of understanding. Past work has argued that surface plasmon resonance (SPR) of the enhancing substrate influences the SERS signal; therefore, the SPR of the extrinsic Raman labels (ERLs) utilized in our SERS-based immunoassay is discussed. Four original research chapters follow the Introduction, each presented as separate manuscripts. Chapter 2 modifies a SERS-based immunoassay previously developed in our group, extending it to the low-level detection of viral pathogens and demonstrating its versatility in terms of analyte type, Chapter 3 investigates the influence of ERL size, material composition, and separation distance between the ERLs and capture substrate on the SERS signal. This chapter links SPR with SERS enhancement factors and is consistent with many of the results from theoretical treatments

  15. Automated processing of label-free Raman microscope images of macrophage cells with standardized regression for high-throughput analysis.

    Science.gov (United States)

    Milewski, Robert J; Kumagai, Yutaro; Fujita, Katsumasa; Standley, Daron M; Smith, Nicholas I

    2010-11-19

    Macrophages represent the front lines of our immune system; they recognize and engulf pathogens or foreign particles thus initiating the immune response. Imaging macrophages presents unique challenges, as most optical techniques require labeling or staining of the cellular compartments in order to resolve organelles, and such stains or labels have the potential to perturb the cell, particularly in cases where incomplete information exists regarding the precise cellular reaction under observation. Label-free imaging techniques such as Raman microscopy are thus valuable tools for studying the transformations that occur in immune cells upon activation, both on the molecular and organelle levels. Due to extremely low signal levels, however, Raman microscopy requires sophisticated image processing techniques for noise reduction and signal extraction. To date, efficient, automated algorithms for resolving sub-cellular features in noisy, multi-dimensional image sets have not been explored extensively. We show that hybrid z-score normalization and standard regression (Z-LSR) can highlight the spectral differences within the cell and provide image contrast dependent on spectral content. In contrast to typical Raman imaging processing methods using multivariate analysis, such as single value decomposition (SVD), our implementation of the Z-LSR method can operate nearly in real-time. In spite of its computational simplicity, Z-LSR can automatically remove background and bias in the signal, improve the resolution of spatially distributed spectral differences and enable sub-cellular features to be resolved in Raman microscopy images of mouse macrophage cells. Significantly, the Z-LSR processed images automatically exhibited subcellular architectures whereas SVD, in general, requires human assistance in selecting the components of interest. The computational efficiency of Z-LSR enables automated resolution of sub-cellular features in large Raman microscopy data sets without

  16. Surfactant-mediated growth of ultrathin Ge and Si films and their interfaces: Interference-enhanced Raman study

    OpenAIRE

    Kanakaraju, S; Sood, AK; Mohan, S

    2000-01-01

    We report on the growth and interfaces of ultrathin polycrystalline Ge and Si films when they are grown on each other using ion beam sputter deposition with and without surfactant at different growth temperatures, studied using interference enhanced Raman spectroscopy. Ge films grown on Si without surfactant show Ge segregation at the interfaces forming an alloy of GexSi1-x as indicated by the Ge-Si Raman mode. However, use of Sb as surfactant strongly suppresses the intermixing. Also Si film...

  17. Probing the adsorption mechanism in thiamazole bound to the silver surface with Surface-enhanced Raman Scattering and DFT

    Science.gov (United States)

    Biswas, Nandita; Thomas, Susy; Sarkar, Anjana; Mukherjee, Tulsi; Kapoor, Sudhir

    2009-09-01

    Surface-enhanced Raman scattering (SERS) of thiamazole have been investigated in aqueous solution. Thiamazole is an important anti-thyroid drug that is used in the treatment of hyperthyroidism (over activity of the thyroid gland). Due to its medicinal importance, the surface adsorption properties of thiamazole have been studied. The experimental Raman and SERS data are supported with DFT calculations using B3LYP functional with LANL2DZ basis set. From the SERS spectra as well as theoretical calculations, it has been inferred that thiamazole is chemisorbed to the silver surface directly through the sulphur atom and the ring N atom, with a tilted orientation.

  18. Light depolarization induced by metallic tips in apertureless near-field optical microscopy and tip-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gucciardi, P G [CNR-Istituto per i Processi Chimico-Fisici, sezione Messina, Salita Sperone, Contrada Papardo, I-98158 Faro Superiore, Messina (Italy); Lopes, M; Deturche, R; Julien, C; Barchiesi, D; Chapelle, M Lamy de la [Institut Charles Delaunay-CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de Technologie de Troyes, 12 rue Marie Curie, BP2060, 10010 Troyes (France)

    2008-05-28

    We have investigated the depolarization effects of light scattered by sharp tips used for apertureless near-field optical microscopy. Dielectric and metal coated tips have been investigated and depolarization factors between 5 and 30% have been measured, changing as a function of the incident light polarization and of the tip shape. The experimental results are in good agreement with theoretical calculations performed by the finite element method, giving a near-field depolarization factor close to 10%. The effect of depolarization has been investigated in polarized tip-enhanced Raman spectroscopy (TERS) experiments; the depolarization gives rise to forbidden Raman modes in Si crystals.

  19. Vibrational imaging and microspectroscopies based on coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Volkmer, Andreas

    2005-01-01

    For noninvasive characterization of chemical species or biological components within a complex heterogeneous system, their intrinsic molecular vibrational properties can be used in contrast mechanisms in optical microscopy. A series of recent advances have made coherent anti-Stokes Raman scattering (CARS) microscopy a powerful technique that allows vibrational imaging with high sensitivity, high spectral resolution and three-dimensional sectioning capability. In this review, we discuss theoretical and experimental aspects of CARS microscopy in a collinear excitation beam geometry. Particular attention is given to the underlying physical principles behind the new features of CARS signal generation under tight focusing conditions. We provide a brief overview of the instrumentation of CARS microscopy and its experimental characterization by means of imaging of model systems and live unstained cells. CARS microscopy offers the possibility of spatially resolved vibrational spectroscopy, providing chemical and physical structure information of molecular specimens on the sub-micrometre length scale. We review multiplex CARS microspectroscopy allowing fast acquisition of frequency-resolved CARS spectra, time-resolved CARS microspectroscopy recording ultrafast Raman free induction decays and CARS correlation spectroscopy probing dynamical processes with chemical selectivity. (topical review)

  20. Visualization and Non-Destructive Quantification of Inkjet-Printed Pharmaceuticals on Different Substrates Using Raman Spectroscopy and Raman Chemical Imaging

    DEFF Research Database (Denmark)

    Edinger, Magnus; Bar-Shalom, Daniel; Rantanen, Jukka

    2017-01-01

    and ethanol was developed. Inkjet printing technology was used to apply haloperidol ink onto three different substrates. Custom-made inorganic compacts and dry foam, as well as marketed paracetamol tablets were used as the substrates. RESULTS: Therapeutic personalized doses were printed by using one to ten...... printing rounds on the substrates. The haloperidol content in the finished dosage forms were determined by high-performance liquid chromatography (HPLC). The distribution of the haloperidol on the dosage forms were visualized using Raman chemical imaging combined with principal components analysis (PCA...... prediction was observed for the paracetamol tablets. It was not possible to quantify haloperidol on the dry foam due to the low and varying density of the substrate. CONCLUSIONS: Raman spectroscopy is a useful tool for visualization and quality control of inkjet printed personalized medicine....

  1. Intraoperative detection of glioma invasion beyond MRI enhancement with Raman spectroscopy in humans

    Science.gov (United States)

    Jermyn, Michael; Mok, Kelvin; Mercier, Jeanne; Desroches, Joannie; Pichette, Julien; Saint-Arnaud, Karl; Guiot, Marie-Christine; Petrecca, Kevin; Leblond, Frédéric

    2015-03-01

    Cancer tissue is frequently impossible to distinguish from normal brain during surgery. Gliomas are a class of brain cancer which invade into the normal brain. If left unresected, these invasive cancer cells are the source of glioma recurrence. Moreover, these invasion areas do not show up on standard-of-care pre-operative Magnetic Resonance Imaging (MRI). This inability to fully visualize invasive brain cancers results in subtotal surgical resections, negatively impacting patient survival. To address this issue, we have demonstrated the efficacy of single-point in vivo Raman spectroscopy using a contact hand-held fiber optic probe for rapid detection of cancer invasion in 8 patients with low and high grade gliomas. Using a supervised machine learning algorithm to analyze the Raman spectra obtained in vivo, we were able to distinguish normal brain from the presence of cancer cells with sensitivity and specificity greater than 90%. Moreover, by correlating these results with pre-operative MRI we demonstrate the ability to detect low density cancer invasion up to 1.5cm beyond the cancer extent visible using MRI. This represents the potential for significant improvements in progression-free and overall patient survival, by identifying previously undetectable residual cancer cell populations and preventing the resection of normal brain tissue. While the importance of maximizing the volume of tumor resection is important for all grades of gliomas, the impact for low grade gliomas can be dramatic because surgery can even be curative. This convenient technology can rapidly classify cancer invasion in real-time, making it ideal for intraoperative use in brain tumor resection.

  2. Electromagnetic study of surface enhanced Raman scattering of plasmonic-biomolecule: An interaction between nanodimer and single biomolecule

    Science.gov (United States)

    Pandey, Gyanendra Krishna; Pathak, Nilesh Kumar; Uma, R.; Sharma, R. P.

    2017-04-01

    In this article we have investigated the electromagnetic surface enhanced Raman scattering (SERS) of single biomolecule adsorbed at the surface of spherical nanodimer. The SERS mechanism has been studied using first principle approach for spherical nanodimer geometry. The coupling of plasmonic concept to biomolecule results the broadband tunable enhancement in Raman gain factor. In this observation the enhancement factor was observed around ≈ 1015. The plasmonic properties of metal nanodimer are analysed in terms of surface plasmon resonances, extinction efficiency and polarisability that have been derived under quasistatic approximation. In this paper, various facets like interdipole separation, molecule distance and size of the plasmonic nanogeometry are taken into account to analyse the Raman gain factor. We also observe that the frequency range expands sufficiently which increases the broad detectability range of the molecule which generates signal even in the outside of Raman range i.e. in between IR to UV region. Lastly, the extinction spectra and electric field profile have been evaluated at resonance wavelength 364 nm. The comparison between electrostatic approach and numerical approach (using DDA) has also been done in terms of extinction spectra.

  3. Surface-enhanced Raman spectroscopic studies of the Au-pentacene interface: a combined experimental and theoretical investigation.

    Science.gov (United States)

    Adil, D; Guha, S

    2013-07-28

    It has recently been shown [D. Adil and S. Guha, J. Phys. Chem. C 116, 12779 (2012)] that a large enhancement in the Raman intensity due to surface-enhanced Raman scattering (SERS) is observed from pentacene when probed through the Au contact in organic field-effect transistors (OFET) structures. Here, the SERS spectrum is shown to exhibit a high sensitivity to disorder introduced in the pentacene film by Au atoms. The Raman signature of the metal-semiconductor interface in pentacene OFETs is calculated with density-functional theory by explicitly considering the Au-pentacene interaction. The observed enhancement in the 1380 cm(-1) and the 1560 cm(-1) regions of the experimental Raman spectrum of pentacene is successfully modeled by Au-pentacene complexes, giving insights into the nature of disorder in the pentacene sp(2) network. Finally, we extend our previous work on high-operating voltage pentacene OFETs to low-operating voltage pentacene OFETs. No changes in the SERS spectra before and after subjecting the OFETs to a bias stress are observed, concurrent with no degradation in the threshold voltage. This shows that bias stress induced performance degradation is, in part, caused by field-induced structural changes in the pentacene molecule. Thus, we confirm that the SERS spectrum can be used as a visualization tool for correlating transport properties to structural changes, if any, in organic semiconductor based devices.

  4. Morphology modification of gold nanoparticles from nanoshell to C-shape: Improved surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    Xing, Ting-Yang; Zhu, Jian; Li, Jian-Jun; Zhao, Jun-Wu

    2016-01-01

    Morphology modification of nanostructures is of great interest, because it can be used to fabricate nanostructures which are hard to be done using other methods. Different from traditional lithographic technique which is slow and expensive, morphology modification is easy, cheap, and reproducible. In this paper, modification of the optical and morphological properties of a hollow gold nanoshell (HGNS) is achieved by using H 2 O 2 as an oxidizer. The reshaping of these nanostructures has been demonstrated as a consequence of an oxidation process in which HGNSs are dissolved by H 2 O 2 under the acidic conditions provided by HCl. We investigate the oxidation process by a transmission electron microscope and propose a reshaping model involving four different shapes (HGNS, HGNS with hole, gold nanoring, and C-shaped gold nanoparticle) which are corresponding to the oxidation products of HGNSs at different pH values. Besides, the surface enhanced Raman scattering (SERS) activity of each oxidation product has been evaluated by using rhodamine 6G as the Raman active probe. It has been observed that the C-shaped gold nanoparticles which are corresponding to the oxidation products at the minimum pH value have the highest SERS activity and this result can also be interpreted by discrete-dipole approximation simulations. We demonstrate that the morphology modification of HGNSs becomes possible in a controlled manner using wet chemistry and can be used in preparation of gold nanoparticles such as HGNS with hole, gold nanoring, and C-shaped gold nanoparticle with large SERS activity. These nanostructures must have potential use in many plasmonic areas, including sensing, catalysis, and biomedicine.

  5. Analysis of silver nanoparticles in antimicrobial products using surface-enhanced Raman spectroscopy (SERS).

    Science.gov (United States)

    Guo, Huiyuan; Zhang, Zhiyun; Xing, Baoshan; Mukherjee, Arnab; Musante, Craig; White, Jason C; He, Lili

    2015-04-07

    Silver nanoparticles (AgNPs) are the most commonly used nanoparticles in consumer products. Concerns over human exposure to and risk from these particles have resulted in increased interest in novel strategies to detect AgNPs. This study investigated the feasibility of surface-enhanced Raman spectroscopy (SERS) as a method for the detection and quantification of AgNPs in antimicrobial products. By using ferbam (ferric dimethyl-dithiocarbamate) as an indicator molecule that binds strongly onto the nanoparticles, AgNPs detection and discrimination were achieved based on the signature SERS response of AgNPs-ferbam complexes. SERS response with ferbam was distinct for silver ions, silver chloride, silver bulk particles, and AgNPs. Two types of AgNPs with different coatings, citrate and polyvinylpirrolidone (PVP), both showed strong interactions with ferbam and induced strong SERS signals. SERS was effectively applicable for detecting Ag particles ranging from 20 to 200 nm, with the highest signal intensity in the 60-100 nm range. A linear relationship (R(2) = 0.9804) between Raman intensity and citrate-AgNPs concentrations (60 nm; 0-20 mg/L) indicates the potential for particle quantification. We also evaluated SERS detection of AgNPs in four commercially available antimicrobial products. Combined with ICP-MS and TEM data, the results indicated that the SERS response is primarily dependent on size, but also affected by AgNPs concentration. The findings demonstrate that SERS is a promising analytical platform for studying environmentally relevant levels of AgNPs in consumer products and related matrices.

  6. Morphology modification of gold nanoparticles from nanoshell to C-shape: Improved surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Ting-Yang; Zhu, Jian; Li, Jian-Jun; Zhao, Jun-Wu, E-mail: nanoptzhao@163.com [The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-06-28

    Morphology modification of nanostructures is of great interest, because it can be used to fabricate nanostructures which are hard to be done using other methods. Different from traditional lithographic technique which is slow and expensive, morphology modification is easy, cheap, and reproducible. In this paper, modification of the optical and morphological properties of a hollow gold nanoshell (HGNS) is achieved by using H{sub 2}O{sub 2} as an oxidizer. The reshaping of these nanostructures has been demonstrated as a consequence of an oxidation process in which HGNSs are dissolved by H{sub 2}O{sub 2} under the acidic conditions provided by HCl. We investigate the oxidation process by a transmission electron microscope and propose a reshaping model involving four different shapes (HGNS, HGNS with hole, gold nanoring, and C-shaped gold nanoparticle) which are corresponding to the oxidation products of HGNSs at different pH values. Besides, the surface enhanced Raman scattering (SERS) activity of each oxidation product has been evaluated by using rhodamine 6G as the Raman active probe. It has been observed that the C-shaped gold nanoparticles which are corresponding to the oxidation products at the minimum pH value have the highest SERS activity and this result can also be interpreted by discrete-dipole approximation simulations. We demonstrate that the morphology modification of HGNSs becomes possible in a controlled manner using wet chemistry and can be used in preparation of gold nanoparticles such as HGNS with hole, gold nanoring, and C-shaped gold nanoparticle with large SERS activity. These nanostructures must have potential use in many plasmonic areas, including sensing, catalysis, and biomedicine.

  7. Real-time biochemical sensor based on Raman scattering with CMOS contact imaging.

    Science.gov (United States)

    Muyun Cao; Yuhua Li; Yadid-Pecht, Orly

    2015-08-01

    This work presents a biochemical sensor based on Raman scattering with Complementary metal-oxide-semiconductor (CMOS) contact imaging. This biochemical optical sensor is designed for detecting the concentration of solutions. The system is built with a laser diode, an optical filter, a sample holder and a commercial CMOS sensor. The output of the system is analyzed by an image processing program. The system provides instant measurements with a resolution of 0.2 to 0.4 Mol. This low cost and easy-operated small scale system is useful in chemical, biomedical and environmental labs for quantitative bio-chemical concentration detection with results reported comparable to a highly cost commercial spectrometer.

  8. Application of surface enhanced Raman scattering and competitive adaptive reweighted sampling on detecting furfural dissolved in transformer oil

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2018-03-01

    Full Text Available Detecting the dissolving furfural in mineral oil is an essential technical method to evaluate the ageing condition of oil-paper insulation and the degradation of mechanical properties. Compared with the traditional detection method, Raman spectroscopy is obviously convenient and timesaving in operation. This study explored the method of applying surface enhanced Raman scattering (SERS on quantitative analysis of the furfural dissolved in oil. Oil solution with different concentration of furfural were prepared and calibrated by high-performance liquid chromatography. Confocal laser Raman spectroscopy (CLRS and SERS technology were employed to acquire Raman spectral data. Monte Carlo cross validation (MCCV was used to eliminate the outliers in sample set, then competitive adaptive reweighted sampling (CARS was developed to select an optimal combination of informative variables that most reflect the chemical properties of concern. Based on selected Raman spectral features, support vector machine (SVM combined with particle swarm algorithm (PSO was used to set up a furfural quantitative analysis model. Finally, the generalization ability and prediction precision of the established method were verified by the samples made in lab. In summary, a new spectral method is proposed to quickly detect furfural in oil, which lays a foundation for evaluating the ageing of oil-paper insulation in oil immersed electrical equipment.

  9. Application of surface enhanced Raman scattering and competitive adaptive reweighted sampling on detecting furfural dissolved in transformer oil

    Science.gov (United States)

    Chen, Weigen; Zou, Jingxin; Wan, Fu; Fan, Zhou; Yang, Dingkun

    2018-03-01

    Detecting the dissolving furfural in mineral oil is an essential technical method to evaluate the ageing condition of oil-paper insulation and the degradation of mechanical properties. Compared with the traditional detection method, Raman spectroscopy is obviously convenient and timesaving in operation. This study explored the method of applying surface enhanced Raman scattering (SERS) on quantitative analysis of the furfural dissolved in oil. Oil solution with different concentration of furfural were prepared and calibrated by high-performance liquid chromatography. Confocal laser Raman spectroscopy (CLRS) and SERS technology were employed to acquire Raman spectral data. Monte Carlo cross validation (MCCV) was used to eliminate the outliers in sample set, then competitive adaptive reweighted sampling (CARS) was developed to select an optimal combination of informative variables that most reflect the chemical properties of concern. Based on selected Raman spectral features, support vector machine (SVM) combined with particle swarm algorithm (PSO) was used to set up a furfural quantitative analysis model. Finally, the generalization ability and prediction precision of the established method were verified by the samples made in lab. In summary, a new spectral method is proposed to quickly detect furfural in oil, which lays a foundation for evaluating the ageing of oil-paper insulation in oil immersed electrical equipment.

  10. Exploring type II microcalcifications in benign and premalignant breast lesions by shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)

    Science.gov (United States)

    Liang, Lijia; Zheng, Chao; Zhang, Haipeng; Xu, Shuping; Zhang, Zhe; Hu, Chengxu; Bi, Lirong; Fan, Zhimin; Han, Bing; Xu, Weiqing

    2014-11-01

    The characteristics of type II microcalcifications in fibroadenoma (FB), atypical ductal hyperplasia (ADH), and ductal carcinoma in situ (DCIS) breast tissues has been analyzed by the fingerprint features of Raman spectroscopy. Fresh breast tissues were first handled to frozen sections and then they were measured by normal Raman spectroscopy. Due to inherently low sensitivity of Raman scattering, Au@SiO2 shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique was utilized. A total number of 71 Raman spectra and 70 SHINERS spectra were obtained from the microcalcifications in benign and premalignant breast tissues. Principal component analysis (PCA) was used to distinguish the type II microcalcifications between these tissues. This is the first time to detect type II microcalcifications in premalignant (ADH and DCIS) breast tissue frozen sections, and also the first time SHINERS has been utilized for breast cancer detection. Conclusions demonstrated in this paper confirm that SHINERS has great potentials to be applied to the identification of breast lesions as an auxiliary method to mammography in the early diagnosis of breast cancer.

  11. The synthesis of four-layer gold-silver-polymer-silver core-shell nanomushroom with inbuilt Raman molecule for surface-enhanced Raman scattering

    Science.gov (United States)

    Jiang, Tao; Wang, Xiaolong; Zhou, Jun

    2017-12-01

    A facial two-step reduction method was proposed to synthesize four-layer gold-silver-polymer-silver (Au@Ag@PSPAA@Ag) core-shell nanomushrooms (NMs) with inbuilt Raman molecule. The surface-enhanced Raman scattering (SERS) intensity of 4MBA adhered on the surface of Au core gradually increased with the modification of middle Ag shell and then Ag mushroom cap due to the formation of two kinds of ultra-small interior nanogap. Compared with the initial Au nanoparticles, the SERS enhancement ratio of the Au@Ag@PSPAA@Ag NMs approached to nearly 40. The novel core-shell NMs also exhibited homogeneous SERS signals for only one sample and reproducible signals for 10 different samples, certified by the low relative standard deviation values of less than 10% and 15% for the character peaks of 4-mercaptobenzoic acid, respectively. Such a novel four-layer core-shell nanostructure with reliable SERS performance has great potential application in quantitative SERS-based immunoassay.

  12. Simultaneous UV Imaging and Raman Spectroscopy for the Measurement of Solvent-Mediated Phase Transformations During Dissolution Testing

    DEFF Research Database (Denmark)

    Ostergaard, Jesper; Wu, Jian; Naelapää, Kaisa

    2014-01-01

    The current work reports the simultaneous use of UV imaging and Raman spectroscopy for detailed characterization of drug dissolution behavior including solid-state phase transformations during dissolution. The dissolution of drug substances from compacts of sodium naproxen in 0.1 HCl as well as t...... of UV imaging and Raman spectroscopy offers a detailed characterization of drug dissolution behavior in a time-effective and sample-sparing manner. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1149-1156, 2014....

  13. In situ surface-enhanced Raman scattering spectroscopy exploring molecular changes of drug-treated cancer cell nucleus.

    Science.gov (United States)

    Liang, Lijia; Huang, Dianshuai; Wang, Hailong; Li, Haibo; Xu, Shuping; Chang, Yixin; Li, Hui; Yang, Ying-Wei; Liang, Chongyang; Xu, Weiqing

    2015-02-17

    Investigating the molecular changes of cancer cell nucleus with drugs treatment is crucial for the design of new anticancer drugs, the development of novel diagnostic strategies, and the advancement of cancer therapy efficiency. In order to better understand the action effects of drugs, accurate location and in situ acquisition of the molecular information of the cell nuclei are necessary. In this work, we report a microspectroscopic technique called dark-field and fluorescence coimaging assisted surface-enhanced Raman scattering (SERS) spectroscopy, combined with nuclear targeting nanoprobes, to in situ study Soma Gastric Cancer (SGC-7901) cell nuclei treated with two model drugs, e.g., DNA binder (Hoechst33342) and anticancer drug (doxorubicin, Dox) via spectral analysis at the molecular level. Nuclear targeting nanoprobes with an assembly structure of thiol-modified polyethylene glycol polymers (PEG) and nuclear localizing signal peptides (NLS) around gold nanorods (AuNRs) were prepared to achieve the amplified SERS signals of biomolecules in the cell nuclei. With the assistance of dark field/fluorescence imaging with simultaneous location, in situ SERS spectra in one cell nucleus were measured and analyzed to disclose the effects of Hoechst33342 and Dox on main biomolecules in the cell nuclei. The experimental results show that this method possesses great potential to investigate the targets of new anticancer drugs and the real-time monitoring of the dynamic changes of cells caused by exogenous molecules.

  14. Surface-enhanced Raman spectroscopy competitive binding biosensor development utilizing surface modification of silver nanocubes and a citrulline aptamer

    Science.gov (United States)

    Walton, Brian M.; Jackson, George W.; Deutz, Nicolaas; Cote, Gerard

    2017-07-01

    A point-of-care (PoC) device with the ability to detect biomarkers at low concentrations in bodily fluids would have an enormous potential for medical diagnostics outside the central laboratory. One method to monitor analytes at low concentrations is by using surface-enhanced Raman spectroscopy (SERS). In this preliminary study toward using SERS for PoC biosensing, the surface of colloidal silver (Ag) nanocubes has been modified to test the feasibility of a competitive binding SERS assay utilizing aptamers against citrulline. Specifically, Ag nanocubes were functionalized with mercaptobenzoic acid, as well as a heterobifunctional polyethylene glycol linker that forms an amide bond with the amino acid citrulline. After the functionalization, the nanocubes were characterized by zeta-potential, transmission electron microscopy images, ultraviolet/visible spectroscopy, and by SERS. The citrulline aptamers were developed and tested using backscattering interferometry. The data show that our surface modification method does work and that the functionalized nanoparticles can be detected using SERS down to a 24.5 picomolar level. Last, we used microscale thermophoresis to show that the aptamers bind to citrulline with at least a 50 times stronger affinity than other amino acids.

  15. Investigation of Surface Enhanced Coherent Raman Scattering on Nano-patterned Insect Wings

    Science.gov (United States)

    Ujj, Laszlo; Lawhead, Carlos

    2015-03-01

    Many insect wings (cicadas, butterflies, mosquitos) poses nano-patterned surface structure. Characterization of surface morphology and chemical composition of insect wings is important to understand the extreme mechanical properties and the biophysical functionalities of the wings. We have measured the image of the membrane of a cicada's wing with the help of Scanning Electron Microscopy (SEM). The results confirm the existing periodic structure of the wing measured previously. In order to identify the chemical composition of the wing, we have deposited silver nanoparticles on it and applied Coherent anti-Stokes Raman Spectroscopy to measure the vibrational spectra of the molecules comprising the wing for the first time. The measured spectra are consistent with the original assumption that the wing membrane is composed of protein, wax, and chitin. The results of these studies can be used to measure other nano-patterned surfaces and to make artificial materials in the future. Authors grateful for financial support from the Department of Physics of the College of Sciences Engineering and Health of UWF and the Pall Corporation for SEM imaging.

  16. Diffraction enhanced imaging: a simple model

    International Nuclear Information System (INIS)

    Zhu Peiping; Yuan Qingxi; Huang Wanxia; Wang Junyue; Shu Hang; Chen Bo; Liu Yijin; Li Enrong; Wu Ziyu

    2006-01-01

    Based on pinhole imaging and conventional x-ray projection imaging, a more general DEI (diffraction enhanced imaging) equation is derived using simple concepts in this paper. Not only can the new DEI equation explain all the same problems as with the DEI equation proposed by Chapman, but also some problems that cannot be explained with the old DEI equation, such as the noise background caused by small angle scattering diffracted by the analyser

  17. Diffraction enhanced imaging: a simple model

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Peiping; Yuan Qingxi; Huang Wanxia; Wang Junyue; Shu Hang; Chen Bo; Liu Yijin; Li Enrong; Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2006-10-07

    Based on pinhole imaging and conventional x-ray projection imaging, a more general DEI (diffraction enhanced imaging) equation is derived using simple concepts in this paper. Not only can the new DEI equation explain all the same problems as with the DEI equation proposed by Chapman, but also some problems that cannot be explained with the old DEI equation, such as the noise background caused by small angle scattering diffracted by the analyser.

  18. Electrical pulse – mediated enhanced delivery of silver nanoparticles into living suspension cells for surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Lin, J; Li, B; Feng, S; Chen, G; Li, Y; Huang, Z; Chen, R; Yu, Y; Huang, H; Lin, S; Li, C; Su, Y; Zeng, H

    2012-01-01

    Electrical pulse-mediated enhanced silver nanoparticles delivery is a much better method for intracellular surface-enhanced Raman spectroscopy (SERS) measurements of suspension cells. Robust and high-quality SERS spectra of living suspension cells were obtained based on an electroporation-SERS method, which can overcomes the shortcoming of non-uniform distribution of silver nanoparticles localized in the cell cytoplasm after electroporation and reduces the amount variance of silver nanoparticles delivered into different cells. The electroporation parameters include three 150 V (375 V/cm) electric pulses of 1, 5, and 5 ms durations respectively. Our results indicate that considerable amount of silver nanoparticles can be rapidly delivered into the human promyelocytic leukemia HL60 cells, and the satisfied SERS spectra were obtained while the viability of the treated cells was highly maintained (91.7%). The electroporation-SERS method offers great potential approach in delivering silver nanoparticles into living suspension cells, which is useful for widely biomedical applications including the real-time intracellular SERS analysis of living cells

  19. Sensitive molecular diagnostics using surface-enhanced resonance Raman scattering (SERRS)

    Science.gov (United States)

    Faulds, Karen; Graham, Duncan; McKenzie, Fiona; MacRae, Douglas; Ricketts, Alastair; Dougan, Jennifer

    2009-02-01

    Surface enhanced resonance Raman scattering (SERRS) is an analytical technique with several advantages over competitive techniques in terms of improved sensitivity and multiplexing. We have made great progress in the development of SERRS as a quantitative analytical method, in particular for the detection of DNA. SERRS is an extremely sensitive and selective technique which when applied to the detection of labelled DNA sequences allows detection limits to be obtained which rival, and in most cases, are better than fluorescence. Here the conditions are explored which will enable the successful detection of DNA using SERRS. The enhancing surface which is used is crucial and in this case suspensions of nanoparticles were used as they allow quantitative behaviour to be achieved and allow analogous systems to current fluorescence based systems to be made. The aggregation conditions required to obtain SERRS of DNA are crucial and herein we describe the use of spermine as an aggregating agent. The nature of the label which is used, be it fluorescent, positively or negatively charged also effects the SERRS response and these conditions are again explored here. We have clearly demonstrated the ability to identify the components of a mixture of 5 analytes in solution by using two different excitation wavelengths and also of a 6-plex using data analysis techniques. These conditions will allow the use of SERRS for the detection of target DNA in a meaningful diagnostic assay.

  20. In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Wang, Fei; Wang, Hua-Lin; Qiu, Yang; Chang, Yu-Long; Long, Yi-Tao

    2015-12-01

    In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation.

  1. Highly efficient construction of oriented sandwich structures for surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Guo Hongyun; Xu Weiqing; Xu Shuping; Zhou Ji; Lombardi, John R

    2013-01-01

    The purpose of this study is to solve the problem of low achievement in fabricating sandwich surface-enhanced Raman scattering (SERS) substrates. We demonstrated a highly efficient sandwich structure by the oriented assembly of metal nanoparticles (NPs) on a periodic hexagonal array of metal nanoprisms with 1,4-benzenedithiol (1,4-BDT) as linkers. The metal nanoprism array was prepared by vacuum deposition of metal on a close-packed polystyrene nanosphere pre-patterned substrate. The metal nanoprism array presents different surface properties from the pits left from the removal of polystyrene nanospheres, which causes linkers to selectively adsorb on the metal nanoprism array and sequentially leads to the oriented immobilization of the second-layer metal NPs, avoiding mismatched orientation. These sandwich SERS substrates were characterized by extinction spectroscopy and atomic force microscopy and their enhancement activity was evaluated under different excitation wavelengths. The sandwich structure greatly increases the achievement of ‘hot spots’ to almost 100% of all the metal nanoprisms and enables a large amplification of SERS signals by a factor of ten. This method has the advantages of simplicity, high efficiency, high throughput, controllability and high reproducibility. It has significance in both the study of SERS substrates and the development of plasmonic devices. (paper)

  2. Surface enhanced Raman spectroscopy (SERS) for in vitro diagnostic testing at the point of care

    Science.gov (United States)

    Marks, Haley; Schechinger, Monika; Garza, Javier; Locke, Andrea; Coté, Gerard

    2017-06-01

    Point-of-care (POC) device development is a growing field that aims to develop low-cost, rapid, sensitive in-vitro diagnostic testing platforms that are portable, self-contained, and can be used anywhere - from modern clinics to remote and low resource areas. In this review, surface enhanced Raman spectroscopy (SERS) is discussed as a solution to facilitating the translation of bioanalytical sensing to the POC. The potential for SERS to meet the widely accepted "ASSURED" (Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable) criterion provided by the World Health Organization is discussed based on recent advances in SERS in vitro assay development. As SERS provides attractive characteristics for multiplexed sensing at low concentration limits with a high degree of specificity, it holds great promise for enhancing current efforts in rapid diagnostic testing. In outlining the progression of SERS techniques over the past years combined with recent developments in smart nanomaterials, high-throughput microfluidics, and low-cost paper diagnostics, an extensive number of new possibilities show potential for translating SERS biosensors to the POC.

  3. Fabrication of large area nanoprism arrays and their application for surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Cui, B; Clime, L; Li, K; Veres, T

    2008-01-01

    This work demonstrates the fabrication of metallic nanoprism (triangular nanostructure) arrays using a low-cost and high-throughput process. In the method, the triangular structure is defined by the shadow of a pyramid during angle evaporation of a metal etching mask. The pyramids were created by nanoimprint lithography in polymethylmethacrylate (PMMA) using a mould having an inverse-pyramid-shaped hole array formed by KOH wet etching of silicon. Silver and gold nanoprism arrays with a period of 200 nm and an edge length of 100 nm have been fabricated and used as effective substrates for surface enhanced Raman spectroscopy (SERS) detection of rhodamine 6G (R6G) molecules. Numerical calculations confirmed the great enhancement of electric field near the sharp nanoprism corners, as well as the detrimental effect of the chromium adhesion layer on localized surface plasmon resonance. The current method can also be used to fabricate non-equilateral nanoprism and three-dimensional (3D) nanopyramid arrays, and it can be readily extended to other metals

  4. Quantitative Determination of Nicotine in a PDMS Microfluidic Channel Using Surface Enhanced Raman Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jae Hyun; Choo, Jae Bum [Hanyang University, Ansan (Korea, Republic of); Kim, Duck Joong [Dankook University, Cheonan (Korea, Republic of); Lee, Sang Hoon [Korea University, Seoul (Korea, Republic of)

    2006-02-15

    Rapid and highly sensitive determination of nicotine in a PDMS microfluidic channel was investigated using surface enhanced Raman spectroscopy (SERS). A three-dimensional PDMS microfluidic channel was fabricated for this purpose. This channel shows a high mixing efficiency because the transverse and vertical dispersions of the fluid occur simultaneously through the upper and lower zig zag-type blocks. A higher efficiency of mixing could also be obtained by splitting each of the confluent streams into two sub-streams that then joined and recombined. The SERS signal was measured after nicotine molecules were effectively adsorbed onto silver nanoparticles by passing through the three-dimensional channel. A quantitative analysis of nicotine was performed based on the measured peak area at 1030 cm{sup -1}. The detection limit was estimated to be below 0.1 ppm. In this work, the SERS detection, in combination with a PDMS microfluidic channel, has been applied to the quantitative analysis of nicotine in aqueous solution. Compared to the other conventional analytical methods, the detection sensitivity was enhanced up to several orders of magnitude.

  5. Gold nanoparticle incorporated inverse opal photonic crystal capillaries for optofluidic surface enhanced Raman spectroscopy.

    Science.gov (United States)

    Zhao, Xiangwei; Xue, Jiangyang; Mu, Zhongde; Huang, Yin; Lu, Meng; Gu, Zhongze

    2015-10-15

    Novel transducers are needed for point of care testing (POCT) devices which aim at facile, sensitive and quick acquisition of health related information. Recent advances in optofluidics offer tremendous opportunities for biological/chemical analysis using extremely small sample volumes. This paper demonstrates nanostructured capillary tubes for surface enhanced Raman spectroscopy (SERS) analysis in a flow-through fashion. The capillary tube integrates the SERS sensor and the nanofluidic structure to synergistically offer sample delivery and analysis functions. Inside the capillary tube, inverse opal photonic crystal (IO PhC) was fabricated using the co-assembly approach to form nanoscale liquid pathways. In the nano-voids of the IO PhC, gold nanoparticles were in situ synthesized and functioned as the SERS hotspots. The advantages of the flow-through SERS sensor are multifold. The capillary effect facilities the sample delivery process, the nanofluidic channels boosts the interaction of analyte and gold nanoparticles, and the PhC structure strengthens the optical field near the SERS hotspots and results in enhanced SERS signals from analytes. As an exemplary demonstration, the sensor was used to measure creatinein spiked in artificial urine samples with detection limit of 0.9 mg/dL. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. DNA Origami Directed Au Nanostar Dimers for Single-Molecule Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Tanwar, Swati; Haldar, Krishna Kanta; Sen, Tapasi

    2017-12-06

    We demonstrate the synthesis of Au nanostar dimers with tunable interparticle gap and controlled stoichiometry assembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red (TR) dye was specifically attached in the junction of the dimerized origami to act as a Raman reporter molecule. The SERS enhancement factors of single TR dye molecules located in the conjunction region in dimer structures having interparticle gaps of 7 and 13 nm are 2 × 10 10 and 8 × 10 9 , respectively, which are strong enough for single analyte detection. The highly enhanced electromagnetic field generated by the plasmon coupling between sharp tips and cores of two Au nanostars in the wide conjunction region allows the accommodation and specific detection of large biomolecules. Such DNA-directed assembled nanoantennas with controlled interparticle separation distance and stoichiometry, and well-defined geometry, can be used as excellent substrates in single-molecule SERS spectroscopy and will have potential applications as a reproducible platform in single-molecule sensing.

  7. Nanotextured thin films for detection of chemicals by surface enhanced Raman scattering

    Science.gov (United States)

    Korivi, Naga; Jiang, Li; Ahmed, Syed; Nujhat, Nabila; Idrees, Mohanad; Rangari, Vijaya

    2017-11-01

    We report on the development of large area, nanostructured films that function as substrates for surface enhanced Raman scattering (SERS) detection of chemicals. The films are made of polyethylene terephthalate layers partially embedded with multi-walled carbon nanotubes and coated with a thin layer of gold. The films are fabricated by a facile method involving spin-coating, acid dip, and magnetron sputtering. The films perform effectively as SERS substrates when used in the detection of dye pollutants such as Congo red dye, with an enhancement factor of 1.1  ×  106 and a detection limit of 10-7 M which is the lowest reported for CR detection by freestanding SERS film substrates. The films have a long shelf life, and cost US0.20 per cm2 of active area, far less than commercially available SERS substrates. This is the first such work on the use of a polymer layer modified with carbon nanotubes to create a nano-scale texture and arbitrary ‘hot-spots’, contributing to the SERS effect.

  8. Self-assembly nanoparticle based tripetaloid structure arrays as surface-enhanced Raman scattering substrates

    International Nuclear Information System (INIS)

    Sun Mingrui; Qian Chuang; Wu Wengang; Yu Wenxuan; Wang Yifei; Mao Haiyang

    2012-01-01

    This paper reports a novel highly ordered tripetaloid structure array (TPSA) which performs very well as an active surface-enhanced Raman scattering (SERS) substrate. The TPSA is easily fabricated by anisotropic etching of a self-assembly silica-nanoparticle bilayer and a subsequent metal deposition step, with notable uniformity and reproducibility. Electromagnetic simulation indicates that the narrow inter-gaps and edge protrusions in the TPSA act as hot spots. In addition, the peak electromagnetic field intensity in the inter-gaps changes slightly and periodically as the polarization of the incident light varies from 0° to 360°. SERS experiments show that the SERS enhancement factor (EF) of a Au-film-covered TPSA is 12 times higher than that of regular Au-film-over-nanoparticles, and not sensitive to the polarization of the incident light. The spatially averaged EF of the TPSA is as high as 5.7 × 10 6 , and the local EF of its hot spots is much higher. (paper)

  9. Toward development of a surface-enhanced Raman scattering (SERS)-based cancer diagnostic immunoassay panel.

    Science.gov (United States)

    Granger, Jennifer H; Granger, Michael C; Firpo, Matthew A; Mulvihill, Sean J; Porter, Marc D

    2013-01-21

    Proteomic analyses of readily obtained human fluids (e.g., serum, urine, and saliva) indicate that the diagnosis of complex diseases will be enhanced by the simultaneous measurement of multiple biomarkers from such samples. This paper describes the development of a nanoparticle-based multiplexed platform that has the potential for simultaneous read-out of large numbers of biomolecules. For this purpose, we have chosen pancreatic adenocarcinoma (PA) as a test bed for diagnosis and prognosis. PA is a devastating form of cancer in which an estimated 86% of diagnoses resulted in death in the United States in 2010. The high mortality rate is due, in part, to the asymptomatic development of the disease and the dearth of sensitive diagnostics available for early detection. One promising route lies in the development of a serum biomarker panel that can generate a signature unique to early stage PA. We describe the design and development of a proof-of-concept PA biomarker immunoassay array coupled with surface-enhanced Raman scattering (SERS) as a sensitive readout method.

  10. Surface enhanced Raman spectroscopy (SERS for in vitro diagnostic testing at the point of care

    Directory of Open Access Journals (Sweden)

    Marks Haley

    2017-06-01

    Full Text Available Point-of-care (POC device development is a growing field that aims to develop low-cost, rapid, sensitive in-vitro diagnostic testing platforms that are portable, self-contained, and can be used anywhere – from modern clinics to remote and low resource areas. In this review, surface enhanced Raman spectroscopy (SERS is discussed as a solution to facilitating the translation of bioanalytical sensing to the POC. The potential for SERS to meet the widely accepted “ASSURED” (Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable criterion provided by the World Health Organization is discussed based on recent advances in SERS in vitro assay development. As SERS provides attractive characteristics for multiplexed sensing at low concentration limits with a high degree of specificity, it holds great promise for enhancing current efforts in rapid diagnostic testing. In outlining the progression of SERS techniques over the past years combined with recent developments in smart nanomaterials, high-throughput microfluidics, and low-cost paper diagnostics, an extensive number of new possibilities show potential for translating SERS biosensors to the POC.

  11. Tuning plasmons layer-by-layer for quantitative colloidal sensing with surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Anderson, William J; Nowinska, Kamila; Hutter, Tanya; Mahajan, Sumeet; Fischlechner, Martin

    2018-04-19

    Surface-enhanced Raman spectroscopy (SERS) is well known for its high sensitivity that emerges due to the plasmonic enhancement of electric fields typically on gold and silver nanostructures. However, difficulties associated with the preparation of nanostructured substrates with uniform and reproducible features limit reliability and quantitation using SERS measurements. In this work we use layer-by-layer (LbL) self-assembly to incorporate multiple functional building blocks of collaborative assemblies of nanoparticles on colloidal spheres to fabricate SERS sensors. Gold nanoparticles (AuNPs) are packaged in discrete layers, effectively 'freezing nano-gaps', on spherical colloidal cores to achieve multifunctionality and reproducible sensing. Coupling between layers tunes the plasmon resonance for optimum SERS signal generation to achieve a 10 nM limit of detection. Significantly, using the layer-by-layer construction, SERS-active AuNP layers are spaced out and thus optically isolated. This uniquely allows the creation of an internal standard within each colloidal sensor to enable highly reproducible self-calibrated sensing. By using 4-mercaptobenzoic acid (4-MBA) as the internal standard adenine concentrations are quantified to an accuracy of 92.6-99.5%. Our versatile approach paves the way for rationally designed yet quantitative colloidal SERS sensors and their use in a variety of sensing applications.

  12. Multiple Image Radiography With Diffraction Enhanced Imaging For Breast Specimen

    International Nuclear Information System (INIS)

    Oltulu, Oral; Zhong Zhong; Hasnah, Moumen; Chapman, Dean

    2007-01-01

    Biological samples are of great interest for many imaging techniques. The samples usually contain small structures and weak absorption properties. The combinations of weak signals with overlying structures make feature recognition difficult in many cases. In the x-ray regime, a relatively new imaging technique Diffraction Enhanced Imaging (DEI) has superior tissue contrast over conventional radiography and is proven to be very sensitive method. Multiple images taken by DEI are called Multiple Image Radiography (MIR). The purpose of this study is to validate the potential application of the method and to show that MIR-DEI method may give more information about the sample

  13. Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

    Science.gov (United States)

    Pavel, Ioana E.; Alnajjar, Khadijeh S.; Monahan, Jennifer L.; Stahler, Adam; Hunter, Nora E.; Weaver, Kent M.; Baker, Joshua D.; Meyerhoefer, Allie J.; Dolson, David A.

    2012-01-01

    A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by…

  14. Gd-DTPA-enhanced dynamic MR imaging

    International Nuclear Information System (INIS)

    Frank, J.A.; Choyke, P.L.; Carvlin, M.; Inscoe, S.; Austin, H.; Dwyer, A.J.; Girton, M.; Black, J.

    1988-01-01

    This paper describes dynamic enhanced renal MR imaging, a new method of identifying specific derangements in renal function. Various diuretics were employed in 45 animal experiments to demonstrate the effects on the normal renal enhancement pattern (EP) after Gd-DTPA. Since different diuretics, osmotic (O), carbonic anhydrase (CA), and loop (L), are active at different sites, specific EP alterations are observed. Imaging was performed with 32 5.1-second sequential gradient recalled acquisition in a steady state images following a bolus of Gd-DTPA

  15. Coherent anti-stokes Raman scattering (CARS) microscopy: a novel technique for imaging the retina.

    Science.gov (United States)

    Masihzadeh, Omid; Ammar, David A; Kahook, Malik Y; Lei, Tim C

    2013-05-01

    To image the cellular and noncellular structures of the retina in an intact mouse eye without the application of exogenous fluorescent labels using noninvasive, nondestructive techniques. Freshly enucleated mouse eyes were imaged using two nonlinear optical techniques: coherent anti-Stokes Raman scattering (CARS) and two-photon autofluorescence (TPAF). Cross sectional transverse sections and sequential flat (en face) sagittal sections were collected from a region of sclera approximately midway between the limbus and optic nerve. Imaging proceeded from the surface of the sclera to a depth of ∼60 μm. The fluorescent signal from collagen fibers within the sclera was evident in the TPAF channel; the scleral collagen fibers showed no organization and appeared randomly packed. The sclera contained regions lacking TPAF and CARS fluorescence of ∼3 to 15 μm in diameter that could represent small vessels or scleral fibroblasts. Intense punctate CARS signals from the retinal pigment epithelial layer were of a size and shape of retinyl storage esters. Rod outer segments could be identified by the CARS signal from their lipid-rich plasma membranes. CARS microscopy can be used to image the outer regions of the mammalian retina without the use of a fluorescent dye or exogenously expressed recombinant protein. With technical advancements, CARS/TPAF may represent a new avenue for noninvasively imaging the retina and might complement modalities currently used in clinical practice.

  16. Tooling Techniques Enhance Medical Imaging

    Science.gov (United States)

    2012-01-01

    They can release as much energy as tens of billions of hydrogen bombs exploding at the same time. They send protons and electrons rocketing at near the speed of light. They heat gas in the Sun s atmosphere to tens of millions of degrees Celsius. They send a blast of gas and particles toward Earth, posing a danger to spacecraft and astronauts outside the planet s magnetosphere, in rare cases even knocking out radio communications and power grids on the ground. They are so-called solar eruptive events, made up of solar flares and the often associated coronal mass ejections. Because of the scientific mystery of how these solar eruptions are produced on the Sun with such scale and force, and also the major role they play in space weather that can impact life on Earth, NASA researchers have innovated new methods of gathering information about these violent events. One NASA mission, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has significantly advanced understanding of solar flares since its launch in 2002. RHESSI scientists use the spacecraft s imaging spectrometer to piece together pictures of solar flares from the high-energy X-ray and gamma-ray radiation they emit. While there is still much to be learned, data gathered by RHESSI has revealed how magnetic fields in the vast expanse of the solar atmosphere may be the force that drives the immense explosions. The instrument has imaged around 50,000 flares to date, providing information that may explain not only the workings of solar flares but also of much more massive energy releases from distant objects like black holes and quasars. We have been able to make images from X-rays with much finer resolution and greater sensitivity than have ever been made before, says Brian Dennis, RHESSI Mission Scientist and astrophysicist in the Solar Physics Laboratory at Goddard Space Flight Center. The key to RHESSI s unprecedented capabilities lie in a set of essential components a NASA partner created for the

  17. Multispectral image enhancement processing for microsat-borne imager

    Science.gov (United States)

    Sun, Jianying; Tan, Zheng; Lv, Qunbo; Pei, Linlin

    2017-10-01

    With the rapid development of remote sensing imaging technology, the micro satellite, one kind of tiny spacecraft, appears during the past few years. A good many studies contribute to dwarfing satellites for imaging purpose. Generally speaking, micro satellites weigh less than 100 kilograms, even less than 50 kilograms, which are slightly larger or smaller than the common miniature refrigerators. However, the optical system design is hard to be perfect due to the satellite room and weight limitation. In most cases, the unprocessed data captured by the imager on the microsatellite cannot meet the application need. Spatial resolution is the key problem. As for remote sensing applications, the higher spatial resolution of images we gain, the wider fields we can apply them. Consequently, how to utilize super resolution (SR) and image fusion to enhance the quality of imagery deserves studying. Our team, the Key Laboratory of Computational Optical Imaging Technology, Academy Opto-Electronics, is devoted to designing high-performance microsat-borne imagers and high-efficiency image processing algorithms. This paper addresses a multispectral image enhancement framework for space-borne imagery, jointing the pan-sharpening and super resolution techniques to deal with the spatial resolution shortcoming of microsatellites. We test the remote sensing images acquired by CX6-02 satellite and give the SR performance. The experiments illustrate the proposed approach provides high-quality images.

  18. Enhancement of image contrast in linacgram through image processing

    International Nuclear Information System (INIS)

    Suh, Hyun Suk; Shin, Hyun Kyo; Lee, Re Na

    2000-01-01

    Conventional radiation therapy portal images gives low contrast images. The purpose of this study was to enhance image contrast of a linacgram by developing a low--cost image processing method. Chest linacgram was obtained by irradiating humanoid phantom and scanned using Diagnostic-Pro scanner for image processing. Several types of scan method were used in scanning. These include optical density scan, histogram equalized scan, linear histogram based scan, linear histogram independent scan, linear optical density scan, logarithmic scan, and power square root scan. The histogram distribution of the scanned images were plotted and the ranges of the gray scale were compared among various scan types. The scanned images were then transformed to the gray window by pallette fitting method and the contrast of the reprocessed portal images were evaluated for image improvement. Portal images of patients were also taken at various anatomic sites and the images were processed by Gray Scale Expansion (GSE) method. The patient images were analyzed to examine the feasibility of using the GSE technique in clinic. The histogram distribution showed that minimum and maximum gray scale ranges of 3192 and 21940 were obtained when the image was scanned using logarithmic method and square root method, respectively. Out of 256 gray scale, only 7 to 30% of the steps were used. After expanding the gray scale to full range, contrast of the portal images were improved. Experiment performed with patient image showed that improved identification of organs were achieved by GSE in portal images of knee joint, head and neck, lung, and pelvis. Phantom study demonstrated that the GSE technique improved image contrast of a linacgram. This indicates that the decrease in image quality resulting from the dual exposure, could be improved by expanding the gray scale. As a result, the improved technique will make it possible to compare the digitally reconstructed radiographs (DRR) and simulation image for

  19. Biological sensing with surface-enhanced Raman spectroscopy (SERS) using a facile and rapid silver colloid-based synthesis technique

    Science.gov (United States)

    Smyth, C.; Mehigan, S.; Rakovich, Y. P.; Bell, S. E. J.; McCabe, E. M.

    2011-03-01

    Optical techniques towards the realisation of sensitive and selective biosensing platforms have received a considerable amount of attention in recent times. Techniques based on interferometry, surface plasmon resonance, field-effect transistors and waveguides have all proved popular, and in particular, spectroscopy offers a large range of options. Raman spectroscopy has always been viewed as an information rich technique in which the vibrational frequencies reveal a lot about the structure of a compound. The issue with Raman spectroscopy has traditionally been that its rather low cross section leads to poor limits-of-detection. In response to this problem, Surface-enhanced Raman Scattering (SERS), which increases sensitivity by bringing the sample in contact with many types of enhanceing substrates, has been developed. Here we discuss a facile and rapid technique for the detection of pterins using colloidal silver suspensions. Pteridine compounds are a family of biochemicals, heterocyclic in structure, and employed in nature as components of colour pigmentation and also as facilitators for many metabolic pathways, particularly those relating to the amino acid hydroxylases. In this work, xanthopterin, isoxanthopterin and 7,8- dihydrobiopterin have been examined whilst absorbed to SERS-active silver colloids. SERS, while far more sensitive than regular Raman spectroscopy, has its own issues relating to the reproducibility of substrates. In order to obtain quantitative data for the pteridine compounds mentioned above, exploratory studies of methods for introducing an internal standard for normalisation of the signals have been carried out.e

  20. Fabrication of bimetallic microfluidic surface-enhanced Raman scattering sensors on paper by screen printing.

    Science.gov (United States)

    Qu, Lu-Lu; Song, Qi-Xia; Li, Yuan-Ting; Peng, Mao-Pan; Li, Da-Wei; Chen, Li-Xia; Fossey, John S; Long, Yi-Tao

    2013-08-20

    Au-Ag bimetallic microfluidic, dumbbell-shaped, surface enhanced Raman scattering (SERS) sensors were fabricated on cellulose paper by screen printing. These printed sensors rely on a sample droplet injection zone, and a SERS detection zone at either end of the dumbbell motif, fabricated by printing silver nanoparticles (Ag NPs) and gold nanoparticles (Au NPs) successively with microscale precision. The microfluidic channel was patterned using an insulating ink to connect these two zones and form a hydrophobic circuit. Owing to capillary action of paper in the millimeter-sized channels, the sensor could enable self-filtering of fluids to remove suspended particles within wastewater without pumping. This sensor also allows sensitive SERS detection, due to advantageous combination of the strong surface enhancement of Ag NPs and excellent chemical stability of Au NPs. The SERS performance of the sensors was investigated by employing the probe rhodamine 6G, a limit of detection (LOD) of 1.1×10(-13)M and an enhancement factor of 8.6×10(6) could be achieved. Moreover, the dumbbell-shaped bimetallic sensors exhibited good stability with SERS performance being maintained over 14 weeks in air, and high reproducibility with less than 15% variation in spot-to-spot SERS intensity. Using these dumbbell-shaped bimetallic sensors, substituted aromatic pollutants in wastewater samples could be quantitatively analyzed, which demonstrated their excellent capability for rapid trace pollutant detection in wastewater samples in the field without pre-separation. Copyright © 2013 Elsevier B.V. All rights reserved.