Дисертації з теми "Surface-Enhanced Spectroscopy"
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1
Zagdoun, Alexandre. "Dynamic Nuclear Polarisation Surface Enhanced NMR Spectroscopy." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2014. http://tel.archives-ouvertes.fr/tel-01065554.
Анотація:
Since its discovery in the 1950's, DNP has been a topic of significant interest in magnetic resonance. DNP is the transfer of polarization between single electrons and nuclei, driven by micro-wave irradiation. Since its renaissance at high field in the 90's, due to the introduction of gyrotrons as high-power, high-frequency microwave sources most application of this technique have been samples of biological interest in frozen solution. The long standing interest of our group in the characterization of surface species such as supported catalysts on silica lead us to apply this technique to the study of surfaces. The goal of this thesis is the development of this method, dubbed DNP Surface Enhanced NMR Spectroscopy. To that end, we first introduce new polarizing agents, soluble in organic solvents. The influence of the electron relaxation times on the DNP enhancements is demonstrated and efficient tailored polarizing agents are introduced. The optimization of the sample preparation to obtain optimal sensitivity is also discussed, as well as the interaction between the radical and the surface. These developments made it possible to apply the technique to many functionalized materials, with some examples developed in this manuscript. Finally, the issue of DNP on polarization conductors is discussed, and we show how microcrystals can be efficiently polarized using DNP.
2
Scherzer, Ryan D. "Degradation Resistant Surface Enhanced Raman Spectroscopy Substrates." UNF Digital Commons, 2017. http://digitalcommons.unf.edu/etd/760.
Анотація:
Raman spectroscopy is employed by NASA, and many others, to detect trace amounts of substances. Unfortunately, the Raman signal is generally too weak to detect when very small, but non-trivial, amounts of molecules are present. One way around this weak signal is to use surface enhanced Raman spectroscopy (SERS).
When used as substrates for SERS, metallic nanorods grown using physical vapor deposition (PVD) provide a large enhancement factor to the Raman signal, as much as 1012. However, Silver (Ag) nanorods that give high enhancement suffer from rapid degradation as a function of time and exposure to harsh environment. Exposure to harsh environments is an enormous issue for NASA; considering all environments experienced during space missions will be drastically different from Earth regarding atmosphere pressure, atmosphere composition, and environmental temperature. Au and Ag nanorods suffer from a thermochemical kinetic phenomenon where the surface atoms diffuse and cause the nanostructures to coalesce towards bulk structure. When in bulk, SERS enhancement is lost and the substrate becomes useless.
A stable structure for SERS detection is designed through engineering the barriers to surface diffusion. Aluminum (Al) nanorods are forced to undergo surface diffusion through thermal annealing and form rough mounds with a stable terminating oxide layer. When Ag is deposited on top of this Al structure, it becomes kinetically bound and changes to physical structure become impeded. Using this paradigm, samples are grown with varied lengths of Ag and are then characterized using scanning electron microscopy (SEM) and Ultraviolet-Visible spectroscopy. The performance of the samples are then tested using SERS experiments for the detection of trace amounts of rhodamine 6G, a ‘gold standard’ analyte. Characterization shows the effectiveness of the Raman substrates remains stable up to 500°C.
Transitioning to basic scientific investigation, next is to strive to isolate the individual impacts of chemical and physical changes to the Ag nanostructure and how they affect the Raman signal. Substrates are compared over the course of a month long experiment to determine the effects of vacuum storage and addressing the effects of chemical adsorbance. Additionally, this was attempted by comparing the signal degradation of Ag nanorods to that of Au, which is known to be chemically inert, allowing for the separation of chemical and physical effects. Although Ag and Au have similar melting points, Ag physically coarsened significantly more. FTIR also showed significant chemical contamination of the Ag, but not Au. A hypothesis is proposed for future investigations into the chemical changes and how they are coupled with and promote the physical changes in nanostructures.
Overall, the novel SERS substrate engineered here may enable the detection of trace amounts of molecules in harsh environments and over long timescales. Conditions such as those found on space missions, where substrates will experience months or years of travel, high vacuum environments, and environments of extreme temperatures.
3
Xie, Yu-Tao. "Surface-enhanced hyper raman and surface-enhanced raman scattering : novel substrates, surface probing molecules and chemical applications /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20XIE.
4
Gant, Virgil Alexander. "Detection of integrins using surface enhanced raman spectroscopy." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2304.
Анотація:
Integrins are transmembrane heterodimer protein receptors that mediate adherence to both the intracellular cytoskeleton and extracellular matrix. They play a major role in cellular adhesion and the breadth of their importance in biology is only recently being understood. The ability to detect concentrations of integrins on the cell surface, spatially resolve them, and study the dynamics of their behavior would be a significant advance in this field. Ultimately, the ability to detect dynamic changes of integrins on the surface of a cell maybe possible by developing a combined device such as an atomic force microscope (AFM) and surface enhanced Raman spectroscopy (SERS) system. However, the focus of this research is to first determine if integrins can be detected using SERS. Surface enhanced Raman spectroscopy (SERS) is technique used to detect the presence of analytes at the nanomolar level or below, through detection of inelastically scattered light. This thesis discusses the detection of integrins employing SERS as the detection modality. Integrins have been detected, in solution, using two silver colloids as the enhancing surface. Two silver colloid preparation methods are compared by ease of formulation and degree of enhancement in this thesis. Citrate and hydroxylamine hydrochloride (HA-HCl) reduced silver colloids were prepared through wet chemistry,compared using UV-Vis light spectroscopy, and tested for surface enhancement using adenine (a strong SERS active molecule), and two different integrins, (alpha)V(beta)3 and (alpha)5(beta)1. Results indicated that both colloids demonstrate SERS activity for varying concentrations of adenine as compared to standard non-enhanced Raman, however, only the citrate reduced colloid showed significant enhancement effect for the integrins.
5
Cunningham, Dale. "Fundamental studies of surface enhanced resonance Raman spectroscopy." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438120.
6
Sockalingum, Dhruvananda. "Surface enhanced Raman spectroscopy in the near-infrared." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315640.
7
Sharma, Narayan. "Solution Processable Surface Enhanced Raman Spectroscopy (SERS) Substrate." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1434375587.
8
Tsoutsi, Dionysia. "Inorganic Ions Sensing by surface-enhanced Raman scattering spectroscopy." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/288213.
Анотація:
En aquest projecte de tesi s'ha aconseguit desenvolupar un sistema de detecció, identificació i quantificació independent d'ions inorgànics. La detecció dels ions es basa en la diferent afinitat cap a diferents lligands orgànics mitjançant l'espectroscòpia de dispersió Raman augmentada per superfícies (surface-enhanced Raman scattering, SERS). En resum, com a substrat s'utilitzaran nanopartícules de plata o microesferes nanoestructurades que es prepararan mitjançant l'adsorció de nanopartícules d'or sobre la superfície de microesferes de sílice a partir del protocol de capa per capa i el seu posterior creixement epitaxial amb plata. Aquest últim pas es realitzarà a través de protocols desenvolupats en el nostre laboratori i té com a objectiu l'obtenció de superfícies plasmòniques discretes altament eficients en SERS. Els substrats es funcionalizaran posteriorment amb lligands orgànics tiolats amb alta afinitat per ions inorgànics (el fluoròfor orgànic, amino-MQAE i la terpiridina, pztpy-DTC). Com a pas següent, es realitzarà la detecció i quantificació simultània dels ions combinant, per a la seva detecció, espectroscòpia SERS. Els canvis espectrals SERS, en la manera de vibració dels lligands organics, estan correlacionats com a funció de la concentració de cada ió amb límits de detecció comparables als de diversos mètodes analítics convencionals.En este proyecto de tesis se ha conseguido desarrollar un sistema de detección, identificación y cuantificación independiente de iones inorgánicos. La detección de los iones se basa en su diferente afinidad hacia diferentes ligandos orgánicos a través de la espectroscopia de dispersión Raman aumentada por superficies (surface-enhanced Raman scattering, SERS). En resumen, como sustrato se utilizarán nanopartículas de plata o microesferas nanoestructuradas que se prepararán mediante la adsorción de nanopartículas de oro sobre la superficie de microesferas de sílice mediante el protocolo de capa por capa y su posterior crecimiento epitaxial con plata. Este último paso se realizará mediante protocolos desarrollados en nuestro laboratorio y tiene como objetivo la obtención de superficies plasmónicas discretas altamente eficientes en SERS. Los sustratos se funcionalizarán posteriormente con ligandos orgánicos tiolados con alta afinidad por iones inorgánicos (el fluoróforo orgánico, amino-MQAE y la terpiridina, pztpy-DTC). Como paso siguiente, se realizará la detección y cuantificación simultánea de los iones combinando para su detección espectroscopia SERS. Los cambios espectrales SERS en el modo de vibración de los ligandos orgánicos están correlacionados como función de la concentración de cada ion con límites de detección comparables a los de varios métodos analíticos convencionales.
In this research project we successfully developed a novel sensing system for the identification and quantification of inorganic ions independently by means of surface-enhanced Raman scattering (SERS) spectroscopy. The detection of the ions is based on their different affinity toward various organic ligands. In summary, we use as SERS-active substrates, either silver nanoparticles or composite nanostructured particles prepared by adsorption of gold nanoparticles on the surface of silica microbeads, using layer-by-layer assembly protocol and the subsequent epitaxial overgrowth of silver. This last step is performed using protocols developed in our laboratory and aims to the fabrication of highly plasmonic surfaces for SERS experiments. Next, the substrates are functionalized with thiolated organic ligands with high affinity toward inorganic ions (amino-MQAE, an organic fluorophore, and pztpy-DTC, a terpyridine). As a further step, the simultaneous identification and quantification of the ions, using SERS spectroscopy, is performed. Vibrational changes in the SERS spectra of the organic ligands are correlated as a function of the concentration of each ion with limits of detection comparable to those of several conventional analytical methods.
9
Yang, Mingwei. "In Situ Arsenic Speciation using Surface-enhanced Raman Spectroscopy." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3387.
Анотація:
Arsenic (As) undergoes extensive metabolism in biological systems involving numerous metabolites with varying toxicities. It is important to obtain reliable information on arsenic speciation for understanding toxicity and relevant modes of action. Currently, popular arsenic speciation techniques, such as chromatographic/electrophoretic separation following extraction of biological samples, may induce the alternation of arsenic species during sample preparation. The present study was aimed to develop novel arsenic speciation methods for biological matrices using surface-enhanced Raman spectroscopy (SERS), which, as a rapid and non-destructive photon scattering technique. The use of silver nanoparticles with different surface coating molecules as SERS substrates permits the measurement of four common arsenicals, including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV). This speciation was successfully carried out using positively charged nanoparticles, and simultaneous detection of arsenicals was achieved. Secondly, arsenic speciation using coffee ring effect-based separation and SERS detection was explored on a silver nanofilm (AgNF), which was prepared by close packing of silver nanoparticles (AgNPs) on a glass substrate surface. Although arsenic separation using the conventional coffee ring effect is difficult because of the limited migration distance, a halo coffee ring was successfully developed through addition of surfactants, and was shown to be capable of arsenicals separation. The surfactants introduced in the sample solution reduce the surface tension of the droplet and generate strong capillary action. Consequently, solvent in the droplet migrated into the peripheral regions and the solvated arsenicals to migrated varying distances due to their differential affinity to AgNF, resulting in a separation of arsenicals in the peripheral region of the coffee ring. Finaly, a method combining experimental Raman spectra measurements and theoretical Raman spectra simulations was developed and employed to obtain Raman spectra of important and emerging arsenic metabolites. These arsenicals include monomethylarsonous acid (MMAIII), dimethylarsinous acid (DMAIII), dimethylmonothioarinic acid (DMMTAV), dimethyldithioarsinic acid (DMDTAV), S-(Dimethylarsenic) cysteine (DMAIIICys) and dimethylarsinous glutathione (DMAIIIGS). The fingerprint vibrational frequencies obtained here for various arsenicals, some of which have not reported previously, provide valuable information for future SERS detection of arsenicals.
10
Grytsyk, Natalia. "Development of the surface-enhanced infrared spectroscopic approach and surface-enhanced Raman spectroscopy coupled with electrochemistry to study reaction mechanism of membrane proteins." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF057/document.
Анотація:
Cette thèse concerne le développement d’approches spectroscopiques infrarouge et Raman exaltées de surface: la spectroscopie infrarouge exaltée de surface (SEIRAS) combinée avec une cellule de perfusion et la spectroscopie Raman exaltée de surface (SERS) couplée avec l’électrochimie. Dans le cadre du premier projet, différentes protéines ont été étudiées : lactose perméase (LacY), complexe I et IM30. Nous avons déterminé le pKa de Glu325 dans LacY sauvage et dans différents mutants portant des mutations dans le centre actif de translocation des protons. Sauvage complexe I a été oxydé avec différents agents oxydants et réduit avec NADH. Spectres différentiels correspondants ont été analysés. Des changements conformationnels dans la protéine IM30, induits par la présence des ions Mg2+, ont été observés.Dans le cadre du deuxième projet, une cellule spectroélectrochimique contenant une grille d’or a été adaptée pour étudier des protéines redox actives. Cette grille d’or sert à la fois de substrat SERS et d’électrode de travail. Cyt c, Hb et Mb ont d'abord été utilisés pour valider la configuration, puis l'approche a été étendue pour étudier une protéine membranaireThis thesis concerns the development of surface-enhanced infrared and Raman spectroscopic approaches: surface-enhanced infrared absorption spectroscopy (SEIRAS) combined with perfusion cell and surface-enhanced Raman spectroscopy (SERS) combined with electrochemistry. Within the first project different proteins were studied: Lactose Permease (LacY), complex I and IM30.The pKa of Glu325 in LacY WT and in different mutants carrying mutations in the proton translocation active center was determined. WT complex I was oxidized with different oxidizing agents and reduced with NADH. Corresponding redox-induced conformational changes were studied. The evidence was given that Mg2+ ions induce conformational changes in the protein IM30.Within the second project the spectroelectrochemical cell containing gold grid electrode was adopted for the studies of redox active proteins. This gold grid serves both as working electrode and as SERS active substrate. First Cyt c, Hb and Mb were used to validate the setup and then the approach was extended to study a membrane protein
11
Huang, Qunjian. "Surface-enhanced raman scattering and surface-enhanced hyper raman scattering : a systematic study of various probing molecules on novel substrates /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202003%20HUANG.
12
Kier, Ruth. "Flow systems for use in surface enhanced resonance raman spectroscopy." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249054.
13
He, Lili Lin Mengshi. "Application of surface enhanced Raman spectroscopy to food safety issues." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6859.
Анотація:
Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 23, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Mengshi Lin. Vita. Includes bibliographical references.
14
Marshall, Addison Robert Lee. "Surface enhanced Raman spectroscopy for single molecule detection and biosensing." Thesis, University of Hull, 2017. http://hydra.hull.ac.uk/resources/hull:16553.
Анотація:
The aim of this thesis is to design plasmonic nano-gaps capable of detecting materials down to sufficiently low concentrations such that single molecule characteristics are observed. We begin first, by discussing the theory of plasmonics. Then, we assess the recent literature on the subject to develop an understanding in the field of plasmonics and to describe the fundamental concepts behind how plasmonic nano-sensors operate. Also, this allows us to show where our research fits in. The aim of this thesis is to design plasmonic nano-gaps capable of detecting materials down to sufficiently low concentrations such that single molecule characteristics are observed. We begin first, by discussing the theory of plasmonics. Then, we assess the recent literature on the subject to develop an understanding in the field of plasmonics and to describe the fundamental concepts behind how plasmonic nano-sensors operate. Also, this allows us to show where our research fits in. The second area of research involves practical Surface Enhanced Raman Spectroscopy (SERS) experiments from our optimized nano-gaps. The nano-gaps were doped with the molecular dyes Rhodamine 6G and Crystal Violet at concentrations of 2x10−7 M. SERS measurements revealed differences in the relative intensities of their respective SERS peaks at low concentrations when compared to the SERS spectra measured from gaps doped the same dye at higher concentrations of 2x10−5 M. Time dependent SERS measurements showed that the SERS signal is stable over a long period of time, indicating the observed relative intensity changes are due to changes in molecular orientation from one gap to another, demonstrating that our optimized nano-gaps have single molecule sensitivity. When exciting at 532 nm, the 118 nm silver spheres used to form the nanogap with the silver film below were shown to enhance the Raman signal by 4:2x relative to the 200 nm silver nano-spheres, and up to 7:73x relative to the 60 nm silver nanospheres. When compared to our simulation results for the same structures excited with a Gaussian source with NA = 0:55, we showed the information collected from the Raman study correlated well with the theoretical data. Following our work investigating single molecule characterisation of fluorescent materials, we began looking at trace levels of a conjugated polymer (F8-PFB). The previous investigation had been from a purely electromagnetic enhancement perspective using a secondary polymer matrix buffer which was optically transparent in the region of interest for the Raman spectra of our target molecule. This polymer provided a barrier between the target material and the metallic nanostructure, thereby minimizing the potential of photo-induced chemical processes in the Raman signal. In this study, the material itself forms the basis of the cavity between the particle and the film below. This system classifies the single molecule regime via the observation of intensity blinking events, which are characteristic of Single Molecule SERS (SM-SERS). We also demonstrated the biosensing applications of our research, where nanoparticle clusters on a metallic film were used to produce spectra from bio-molecules undergoing conformation changes as a result of UV light exposure. The SERS spectra revealed decreased intensity from the Tryptophan (Trp) modes and appearance of disulphide bonds as time under UV light exposure progresses for lysozyme. Our final chapter shows that by using nanoparticles coupled to different substrates such as Distributed Bragg Reflectors (DBRs) and dielectric slabs, the hybrid modes improved the Quality-factor (Q-factor) of the scattering spectra. Therefore, these systems theoretically have great potential for refractive index sensing with high sensitivity to binding activity of molecular targets. The highest Q-factor of the systems we investigated was the 200 nm gold particle coupled to the 2 μm dielectric slab at 22:48, followed by the same particle deposited on a 700 nm stop-band DBR at 7:41.
15
Nicolson, Fay. "Through barrier detection using surface enhanced spatially offset Raman spectroscopy." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30290.
Анотація:
In the fields of security and biomedical imaging there is a significant need to non-invasively probe through barriers, e.g. plastic, glass or tissue. Raman spectroscopy provides a means to solving this challenge since it provides a unique chemical fingerprint without the need to destroy the sample. In spite of this, conventional Raman can be limited by sample volume and thickness, often failing to probe beneath the surface or through samples obscured by an opaque barrier. Spatially offset Raman spectroscopy provides a means of overcoming the limitation associated with conventional Raman spectroscopy since it is capable of providing a unique chemical fingerprint of the analyte understudy, even when obscuring barriers such as plastic or tissue are present. Furthermore, by combining the depth penetration benefits of SORS with the signal enhancing capabilities of SERS, SESORS is capable of achieving sample interrogation at even greater depth. Therefore, the focus of this research is to probe through barriers, specifically plastic and tissue, using both handheld CR and SORS instruments. The ability of both techniques to detect Raman and SERS analytes through barriers is explored and compared for applications involving security and biomedicine. The use of conventional Raman and SORS to detect ethanol through varying thicknesses of plastic is investigated. Raman signals from an ethanol solution through plastic was detected through thicknesses of up to 21 mm using SORS in combination with multivariate analysis. SORS was compared to conventional Raman, where through barrier detection of ethanol took place through depths up to 9 mm. Using a handheld SORS spectrometer, the detection of ex vivo breast cancer tumour models containing SERRS active nanotags through 15 mm of porcine tissue is demonstrated. In addition, SERRS-active nanotags were tracked through porcine tissue to depths of up to 25 mm. To date, this is the largest thickness that SERRS nanotags have been tracked through using a backscattering approach. 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. The same ex vivo tumour models are also used to demonstrate a multiplexed imaging system through depths of 10 mm using back scattering SESORRS. The benefit of using red-shifted chalcogenpyrylium based Raman reporters for probing through large thicknesses of plastic and tissue barriers using SERS is also highlighted. Raman signals were collected from SERRS active nanotags through plastic thicknesses of up to 20 mm. The detection of SERRS-active nanotags taken up into ex vivo tumour models through depths of 5 mm of tissue is also shown. The advantages of applying multivariate analysis for through barrier detection when discriminating analytes with similar spectral features as the barrier is also clearly demonstrated. Finally, resonant chalcogenpyrylium nanotags were used to demonstrate the benefit of using a resonant Raman reporter for superior low-level limits of detection using SESORS. Nanotags containing chalcogenpyrylium dye were observed at concentrations as low as 1 pM through 5 mm of tissue. This is compared to the non-resonant small molecule Raman reporter BPE which could only be detected at concentrations of 11 pM. Calculated limits of detection suggest that these SERRS nanotags can be detected at concentrations as low as 104 fM using SESORRS.
16
Panagoulia, Danai. "Surface enhanced Raman spectroscopy of the ionic liquid-metal interface." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/422133/.
Анотація:
When a charge is applied to an electrode in the metal – Ionic Liquid (IL) interface, an electrochemical double layer is expected to form due to the arrangement of ions to counter the charge on the electrode surface. However, this arrangement of ions in ILs can be complicated by effects such as specific adsorption, ion re-orientation and superoxide ion and Au oxide formation. Traditional techniques used in the study of metal-IL interfaces, have provided a good indication of underlying processes. However, additional proof from new methods is required, as interpretations of the results sometimes vary. In this work, surface enhanced Raman (SERS) spectra have been acquired from the electrochemically controlled interface between Au and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP TFSI). By analysing the intensity and positions of peaks in the spectra corresponding to specific vibrations in the different ions of the IL, useful information has been obtained about the processes occurring at the interface at a molecular level. By using impedance spectroscopy, the potential of zero charge (PZC) was tentatively assigned to -0.85 V vs. PQRE. Cathodic features in cyclic voltammograms and in current-potential data of the SERS experiment, at potentials negative to the PZC, have been assigned to the re-orienting of the BMP cations, increase in axial BMP conformers and superoxide ion formation, tying together varying interpretations from the literature. Au oxide formation from trace water was detected in the SERS spectra and corresponded to a small increase in current at positive potentials. Due to the high concentration of ions in ILs, the effect of the bulk signal on Raman and SERS spectra of ILs has also been examined. The depth resolution of the spectrometer, the SERS signal decay with distance from the substrate and the concentration of molecules in the analyte, have all been taken into account.
17
Hansson, Freja. "Detection of Contaminants in Water Using Surface Enhanced Raman Spectroscopy." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85943.
Анотація:
Due to deteriorating water quality and the world’s increasing demand for clean water, the need for cheap, easy and portable techniques to characterize and quantify pollutants in waters is urgent. Hence, surface-enhanced Raman spectroscopy (SERS) have gained considerable attention in this field. Atrazine and bentazon are two of the most occurring pesticides causing pollution in Sweden, and where therefore examined in this study, along with 4-mercaptopyridine (mpy) as a reference molecule. In this project, silver and gold nanoparticles where synthesised and used as SERS substrates for detection of contaminants in water by using a handheld Raman device provided by Serstech AB. Sodium chloride (NaCl) and magnesium sulfate (MgSO4) where used as aggregation agents allowing the nanoparticles to form hot spots. Mpy was detected to 0.5 nM and an enhancement factor of 108 using silver nanoparticles aggregated with NaCl was obtained. No Raman signal was obtained from atrazine nor bentazon using the handheld Raman device with silver nanoparticles aggregated with NaCl. Therefore the Raman cross-section of the probe molecules where investigated using the handheld Raman device and a conventional Raman device. Bentazon was not detectable using the handheld Raman device but detectable using a conventional Raman device. Atrazine was detectable at high concentrations i.e. atrazine powder using the handheld Raman device and detectable at 100 nM using a conventional Raman device. Since bentazon was not detectable with the handheld Raman device, more focus was put on getting a detectable signal from atrazine using the handheld Raman device. Investigation of the adsorption of atrazine and bentazon to the silver nanoparticle surface was performed. Due to the weaker adsorption to the nanoparticle surface, MgSO4 was used aggregation agent instead of NaCl with mpy, atrazine and bentazon. Mpy was detectable using MgSO4 as aggregation agent, atrazine and bentazon was not. Measurements of mpy, atrazine and bentazon without any salt was performed. For these measurements, no detectable signal from neither molecule was obtained, indicating that the formation of hot spots is necessary to obtained a detectable Raman signal. Measurements of mpy and atrazine with gold nanostars where performed. Enhancement factor using the gold nanostars was calculated to 107, and a detectrable signal from mpy was obtained, not from atrazine. Measurements of atrazine and mpy simultaneously was performed, where mpy peaks was observed but no atrazine peaks. The affinity of the probe molecule and the nanoparticle is crucial to obtain a detectable signal. This study inducates that both the chemical enhancement and electromagnetic enhancement are needed to obtain a detectable signal. For that, strongly binding species is necessary. Considering the simplicity of this method and the limited optimization efforts, there is plenty of room for improvements, including different probe molecules and different SERS substrates. With the right conditions, the evaluated technique reveals a promising and accessible method using a commercially available handheld Raman spectrometer for detection and quantification of contaminants in water.
18
Wei, Haoran. "Surface-Enhanced Raman Spectroscopy for Environmental Analysis: Optimization and Quantitation." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/93204.
Анотація:
Fast, sensitive, quantitative, and low-cost analysis of environmental pollutants is highly valuable for environmental monitoring. Due to its single-molecule sensitivity and fingerprint specificity, surface-enhanced Raman spectroscopy (SERS) has been widely employed for heavy metal, organic compound, and pathogen detection. However, SERS quantitation is challenging because 1) analytes do not stay in the strongest enhancing region ("hot spots") and 2) SERS reproducibility is poor. In this dissertation, gold nanoparticle/bacterial cellulose (AuNP/BC) substrates were developed to improve SERS sensitivity by increasing hot spot density within the laser excitation volume. Environmentally relevant organic amines were fixed at "hot spots" by lowering solution pH below the analyte pKa and thus enabling SERS quantitation. In addition, a new SERS internal standard was developed based upon the electromagnetic enhancement mechanism that relates Rayleigh (elastic) and Raman (in-elastic) scattering. Rayleigh scattering arising from the amplified spontaneous emission of the excitation laser was employed as a normalization factor to minimize the inherent SERS signal variation caused by the heterogeneous distribution of "hot spots" across a SERS substrate. This highly novel technique, hot spot-normalized SERS (HSNSERS), was subsequently applied to evaluate the efficiency of SERS substrates, provide in situ monitoring of ligand exchange kinetics on the AuNP surface, and to reveal the relationship between the pKa of aromatic amines and their affinity to citrate-coated AuNPs (cit-AuNPs). Finally, colloidally stable stable pH nanoprobes were synthesized using co-solvent mediated AuNP aggregation and subsequent coating of poly(ethylene) glycol (PEG). These nanoprobes were applied for pH detection in cancer cells and in phosphate buffered aerosol droplets. The latter experiments suggest that stable pH gradients exist in aerosol droplets.PHD
19
Tian, Hong. "Investigation of Thin Molecular Films by Surface Enhanced Vibrational Spectroscopy." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1227038646.
20
Chowdhury, Mustafa Habib. "The use of Surface Enhanced Raman Spectroscopy (SERS) for biomedical applications." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4816.
Анотація:
Recent advances in nanotechnology and the biotechnology revolution have
created an immense opportunity for the use of noble metal nanoparticles as Surface
Enhanced Raman Spectroscopy (SERS) substrates for biological sensing and diagnostics.
This is because SERS enhances the intensity of the Raman scattered signal from an
analyte by orders of 106 or more. This dissertation deals with the different aspects
involved in the application of SERS for biosensing. It discusses initial studies performed
using traditional chemically reduced silver colloidal nanoparticles for the SERS
detection of a myriad of proteins and nucleic acids. It examines ways to circumvent the
inherent aggregation problems associated with colloidal nanoparticles that frequently
lead to poor data reproducibility. The different methods examined to create robust SERS
substrates include the creation of thermally evaporated silver island films on microscope
glass slides, using the technique of Nanosphere Lithography (NSL) to create
hexagonally close packed periodic particle arrays of silver nanoparticles on glass
substrates as well as the use of optically tunable gold nanoshell films on glass substrates. The three different types of SERS surfaces are characterized using UV-Vis absorption
spectroscopy, Electron Microscopy (EM), Atomic Force Microscopy (AFM) as well as
SERS using the model Raman active molecule trans-1,2-bis(4-pyridyl)ethylene (BPE).
Also discussed is ongoing work in the initial stages of the development of a SERS based
biosensor using gold nanoshell films for the direct detection of b-amyloid, the causative
agent for Alzheimer's disease. Lastly, the use of gold nanoshells as SERS substrates for
the intracellular detection of various biomolecules within mouse fibroblast cells in cell
culture is discussed. The dissertation puts into perspective how this study can represent
the first steps in the development of a robust gold nanoshell based SERS biosensor that
can improve the ability to monitor biological processes in real time, thus providing new
avenues for designing systems for the early diagnosis of diseases.
21
Syed, Azfar A. "Surface enhanced Raman spectroscopy for ultra-sensitive detection of energetic materials." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4644.
Анотація:
The prospect of ultra-sensitive detection of molecular species, particularly those of energetic materials, has prompted the present research initiative. The combination of metal surface nano-technology and Raman spectroscopy has given rise to ‘Surface Enhanced Raman Spectroscopy’ (SERS). This is a very sensitive technique and has proved to be capable of detecting a single molecule. SERS was demonstrated by recording Raman spectra of the sample molecules adsorbed on various specially prepared SER-active surfaces both in the form of a colloidal suspension and on the solid roughened surfaces. Using a gold colloidal suspension, pyridine has been detected down to 10-11 molar (M) concentration. A silver slab was roughened to a dimension of a nano-scale by etching in nitric acid solution to make SER-active surface. Pentaerythritol Tetranitrate (PETN) explosive was detected using this surface after its 10-2 M solution was dropped, dried and washed (of any residue) from the surface. Lithographically engineered silver structures in the form of nanoarrays having a number of silver structures of approximately 106 in a region of 0.1 mm2 have been used for SERS. The major noise contribution to the scattering from impurities in an ordinary glass substrate has been eliminated by replacing glasses as substrates with pure quartz discs. The headspace vapours from peroxide explosives, Triacetone Triperoxide (TATP) and Hexamethylene Triperoxide Diamine (HMTD), were detected at approximately 70 parts per million (ppm) and 0.3 ppm concentrations respectively using a portable commercial Raman Spectrometer. PETN was also detected from its headspace vapour at about 18 parts per trillion (ppt) in spite of it having a much lower vapour pressure. The possibility of desorption of adsorbed molecules from a nano-structured surface by laser irradiation has been demonstrated experimentally with the aim of reusability of SER-active surfaces. Also demonstrated was the enhancement in Raman intensity through resonance Raman effect spectroscopy for the future use in surface enhanced resonance Raman spectroscopy (SERRS).
22
Israelsen, Nathan. "Surface-Enhanced Raman Spectroscopy-Based Biomarker Detection for B-Cell Malignancies." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4605.
Анотація:
This thesis presents a light scattering-based method for biomarker detection, which could potentially be used for the quantification of multiple biomarkers specific to B-cell malignancies. This method uses fabricated gold nanoparticle probes to amplify inelastic light scattering in a process referred to as surface-enhanced Raman scattering. These gold nanoparticle probes were conjugated to antibodies for specific and targeted molecular binding. The spectrum of the amplified inelastic light scattering was detected using a spectrometer and a detector. To detect the light scattering signal from the gold nanoparticle probes, several commercial Raman spectrometer instruments were evaluated. Initial results from these evaluations are presented in this thesis. After system evaluation, a custom Raman microscope system was designed, built, and tested. This system was used for the development of a surface-enhanced Raman spectroscopy-based immunoassay. The development of this assay confirms the successful design of gold nanoparticle probes for the specific targeting and detection of immunoglobulins. The immunoassay also shows promise for the simultaneous detection of multiple biomarkers specific to B-cell malignancies.
23
Wigginton, Krista Rule. "Surface Enhanced Raman Spectroscopy as a Tool for Waterborne Pathogen Testing." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29330.
Анотація:
The development of a waterborne pathogen detection method that is rapid, multiplex, sensitive, and specific, would be of great assistance for water treatment facilities and would help protect water consumers from harmful pathogens. Here we have utilized surface enhanced Raman spectroscopy (SERS) in a sensitive multiplex pathogen detection method. Two strategies are proposed herein, one that utilizes SERS antibody labels and one that measures the intrinsic SERS signal of organisms. For the SERS label strategy, gold nanoparticles are conjugated with antibodies specific to Cryptosporidium parvum and Giardia lamblia and with organic dye molecules. The dye molecules, rhodamine B isothiocyanate (RBITC) and malachite green isothiocyanate (MGITC) were surface enhanced by the gold nanoparticles resulting in unique fingerprint SERS spectra. The SERS label method was successful in detecting G. lamblia and C. parvum simultaneously. The method was subsequently coupled with a filtration step to both concentrate and capture cysts on a flat surface for detection. Raman mapping across the filter membrane detected ~95% of the spiked cysts in the optimized system.
In the second type of strategy, intrinsic virus SERS signals were detected with silver nanoparticles for enhancement. Principal component analysis performed on the spectra data set resulted in the successful differentiation of MS2 and PhiX174 species and also for the differentiation of viable virus samples and inactivated virus samples.Ph. D.
24
Jain, Ishan. "Paper-Based Sensors for Contaminant Detection Using Surface Enhanced Raman Spectroscopy." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/53946.
Анотація:
Surface enhanced Raman spectroscopy (SERS) is highly promising analytical technique for trace detection of analytes. It is particularly well suited for environmental analyses due to its high sensitivity, specificity, ease of operation and rapidity. The detection and characterization of environmental contaminants, using SERS is highly related to the uniformity, activity and reproducibility of the SERS substrate.
In this thesis, SERS substrates were produced by gold nanoparticle formation on wax patterned chromatography paper. In situ reduction of hydrogen tetrachloroaurate (gold precursor) by trisodium citrate dihydrate (reducing agent) was used to produce gold nanoparticles within a paper matrix. These gold nanoparticle based SERS substrates were analyzed by FE-SEM, UV-Vis and Raman spectroscopy. This work discusses the SERS signal enhancements for Raman active MGITC dye for a series of substrates prepared by in situ reduction of gold salt and pre-produced gold nanoparticles. UV-Vis analysis was performed to understand the effect of different molar ratio (reducing agent to gold precursor) and reaction time on the size and shape of the localized surface plasmon resonance (LSPR) band that dictates the SERS enhancements. It was concluded that lower molar ratio (1:1 and 2:1) of citrate-to gold produced better SERS signal enhancements and broader LSPR band. Therefore, use of lower molar ratio (MR) was recommended for paper-based substrates using in situ-based reduction approach.Master of Science
25
Shadi, Iqbal Tahear. "Surface enhanced resonance Raman spectroscopy of dyes : semi-quantitative trace analysis." Thesis, University of Greenwich, 2005. http://gala.gre.ac.uk/6296/.
Анотація:
Herein analysis of dye molecules has been carried out by means of surface enhanced Raman spectroscopy (SERS) and/or surface enhanced resonance Raman spectroscopy (SERRS) using citrate- and/or borohydride-reduced silver colloids employing laser exciting wavelengths equal to 514.5 and/or 632.8 nm. SERS and/or SERRS spectra are reported using, as model system probes, eight dye molecules which belong to several distinct chemical structural classes. Experimental protocols were developed and subsequently modified, as required, for each dye molecule examined. Vibrational spectroscopic profiles were obtained, where possible, with respect to concentration and pH dependence. SERS and/or SERRS vibrational bands provided unique fingerprint spectra for each dye molecule. In an attempt to develop novel applications of SERRS the technique has been used, in a kinetic investigation, to monitor and analyse the synthesis of the dye indigo carmine from indigo using a silver sol as the SERRS substrate/medium. In another study it was possible to differentiate between two structurally similar anthraquinones, alizarin and purpurin, using SERRS. It was also possible to demonstrate the existence of multiple molecular species of certain dye molecules, as a function of pH e.g. nuclear fast red, metanil yellow, purpurin and alizarin. For some dye molecules e.g. alcian blue it was possible to combine the linear regions of normal (non-resonance/non-enhanced) Raman and SERS/SERRS plots, thereby extending the dynamic range available for semi-quantitative analysis. The sensitivity of the SERS/SERRS technique for semi-quantitative trace analysis of eight dye molecules has been successfully demonstrated.
26
Syed, A. A. "Surface enhanced raman spectroscopy for ultra-sensitive detection of energetic materials." Thesis, Department of Materials and Applied Science, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4644.
Анотація:
The prospect of ultra-sensitive detection of molecular species, particularly those of
energetic materials, has prompted the present research initiative. The combination of
metal surface nano-technology and Raman spectroscopy has given rise to ‘Surface
Enhanced Raman Spectroscopy’ (SERS). This is a very sensitive technique and has
proved to be capable of detecting a single molecule.
SERS was demonstrated by recording Raman spectra of the sample molecules adsorbed
on various specially prepared SER-active surfaces both in the form of a colloidal
suspension and on the solid roughened surfaces. Using a gold colloidal suspension,
pyridine has been detected down to 10-11 molar (M) concentration. A silver slab was
roughened to a dimension of a nano-scale by etching in nitric acid solution to make
SER-active surface. Pentaerythritol Tetranitrate (PETN) explosive was detected using
this surface after its 10-2 M solution was dropped, dried and washed (of any residue)
from the surface. Lithographically engineered silver structures in the form of nanoarrays
having a number of silver structures of approximately 106 in a region of 0.1 mm2
have been used for SERS. The major noise contribution to the scattering from
impurities in an ordinary glass substrate has been eliminated by replacing glasses as
substrates with pure quartz discs. The headspace vapours from peroxide explosives,
Triacetone Triperoxide (TATP) and Hexamethylene Triperoxide Diamine (HMTD),
were detected at approximately 70 parts per million (ppm) and 0.3 ppm concentrations
respectively using a portable commercial Raman Spectrometer. PETN was also detected
from its headspace vapour at about 18 parts per trillion (ppt) in spite of it having a much
lower vapour pressure.
The possibility of desorption of adsorbed molecules from a nano-structured surface by
laser irradiation has been demonstrated experimentally with the aim of reusability of
SER-active surfaces. Also demonstrated was the enhancement in Raman intensity
through resonance Raman effect spectroscopy for the future use in surface enhanced
resonance Raman spectroscopy (SERRS).
27
Berruyer, Pierrick. "Three-Dimensional Structure Determination of Surface Sites with Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN042/document.
Анотація:
La capacité à déterminer les structures moléculaires en trois dimensions à partir de monocristaux par des méthodes de diffraction a transformé la chimie des matériaux. Le problème de la détermination de structure est en grande partie non résolu, en particulier si le système étudié est situé à une surface et n'a pas de périodicité, comme dans la plupart des matériaux fonctionnels actuels. La Résonance Magnétique Nucléaire (RMN) à l’état solide serait une méthode de choix pour caractériser les surfaces mais la limite de détection de la RMN est beaucoup trop faible pour permettre à la RMN de caractériser les surfaces. L’introduction récente d’une nouvelle approche utilisant la Polarisation Dynamique Nucléaire (DNP) pour améliorer la sensibilité de la RMN des surfaces (DNP SENS) permet à présent de réaliser des expériences qui étaient totalement impossible il y a quelques années encore. Plus particulièrement, grâce à la méthode DNP SENS, les présents travaux de thèse aboutissent à la première structure tridimensionnelle d’un complexe organométallique supporté sur silice, avec une précision de 0,7 Å. De nombreux aspects de l’expérience DNP SENS ont été exploré. Le transport de de l’hyperpolarisation par diffusion de spin est primordial et un modèle numérique dans les matériaux mésoporeux a été développé. De plus, une nouvelle matrice aqueuse se basant sur des gels polyacrylamides a été mise au point et utilisée pour la caractérisation par RMN de nanoparticules permettant ainsi d’étendre les domaines d’application de DNP SENS. Enfin les premières expériences RMN DNP combinant hauts champs magnétiques et haute fréquence de rotation d’échantillon sont présentéesThe ability to understand the properties of chemical systems relies on their detailed description at the molecular level. Over the last century, several methods based on X-ray diffraction have allowed a structure-based understanding of many materials. However, several key questions often remain unanswered. In particular when the system under investigation is located on a surface. Although an extensive range of surface-sensitive methods are available for surface science and give valuable information, they only lead to a partial understanding of surfaces at the molecular level. Moreover, these methods are not compatible with all kinds of materials and usually require the use of a model and pristine surface. Solid-State NMR would be a method of choice to characterize surfaces. However, the approach suffers from its intrinsically low sensitivity and this is strongly emphasize in the case of surfaces where the atoms of interest are diluted in the matrix. Dynamic Nuclear Polarization (DNP) applied to surfaces (SENS) recently emerged as a very promising method to characterize surface sites. It offers a dramatic enhancement of NMR sensitivity and DNP applied to materials has led to many examples in the last ten years. In the present thesis, I have shown that DNP SENS, in combination with EXAFS, allowed the detailed 3D structure determination of the silica-supported organometallic complex determined with a precision of 0.7 angstroms. In parallel, some experimental aspect of DNP SENS have been explored. A spin diffusion has been developed to understand diffusion of hyperpolarization in porous media. A new aqueous DNP matrix, coined DNP Jelly, has been developed to characterize nanoparticles and thus expanding experimental range of DNP SENS. Finally, the first experiment of DNP NMR at fast magic angle spinning (up to 40 kHz) and high field are reported
28
Boddu, Naresh Kumar. "Trace analysis of biological compounds by surface enhanced Raman scattering (SERS) spectroscopy /." Connect to resource online, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1229542206.
29
Touzalin, Thomas. "Tip-enhanced Raman spectroscopy on electrochemical systems." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS364.
Анотація:
L'analyse in situ d'interfaces électrochimiques à l'échelle nanométriques est un enjeu majeur pour la compréhension des mécanismes de transferts de charges et d'électrons dans les domaines du stockage d'énergie ou de l'électrocatalyse. Ce travail a permis le développement de la spectroscopie Raman exaltée de pointe (TERS) en milieu liquide et en conditions électrochimiques. Le TERS permet l'analyse de la structure de molécules ou de matériaux à l'échelle nanométrique du fait de l'exaltation localisée du champ électrique à l'extrémité d'une sonde de microscope à effet tunnel (STM) en or ou en argent. Un dispositif reposant sur l'illumination d'une pointe au travers d'un solvant organique a démontré la possibilité d'imager les inhomogénéités d'une monocouche auto-assemblée sur or. Une seconde approche reposant sur l'exaltation du signal Raman à l'apex d'une pointe de taille nanométrique utilisée comme microélectrode (spectroscopie Raman exaltée de surface de pointe, tip SERS) a permis de suivre la réduction d'une monocouche auto-assemblée et d'améliorer la compréhension de son mécanisme. Afin d'imager la surface d'une électrode polarisée, le couplage d'un STM utilisant une pointe TERS en conditions électrochimiques a montré une résolution latérale de moins de 8 nm pour sonder de variations locales de l'exaltation du champ électromagnétique induites par des singularités géométriques de surface. Par ailleurs, l'analyse TERS de couches organiques formées à partir de sels d'aryldiazoniums a permis de montrer des différences de structures selon type de greffage. Ce travail constitue donc une avancée majeure pour l'analyse locale de surfaces modifiéesThe in situ investigation of electrochemical interfaces structures at the nanoscale is a key element in the understanding of charge and electron transfer mechanisms e.g. in the fields of energy storage or electrocatalysis. This thesis introduces the implementation of tip-enhanced Raman spectroscopy (TERS) in liquid and in electrochemical conditions enabling the nanoscale analysis of electrified solid/liquid interfaces through the strong and local electric field enhancement at gold or silver scanning tunneling microscopy (STM) probes. The ability of TERS to image inhomogeneities in the coverage density of a self-assembled monolayer (SAM) through a layer of organic solvent on gold was demonstrated. A TERS-inspired analytical tool was also developed, based on a TERS tip used simultaneously as a single-hot spot surface-enhanced Raman spectroscopy (SERS) platform and as a microelectrode (EC tip SERS). The reduction of an electroactive SAM could then be monitored by electrochemical and in situ SERS measurements. In situ electrochemical STM-TERS was also evidenced through the imaging of local variations of the electric field enhancement on peculiar sites of a gold electrode with a lateral resolution lower than 8 nm. Finally TERS also demonstrated to be efficient in investigating the structure of organic layers grafted either by electrochemical reduction or spontaneously. This work is therefore a major advance for the analysis of functionalized surfaces
30
Sheremet, E., A. G. Milekhin, R. D. Rodriguez, T. Weiss, M. Nesterov, E. E. Rodyakina, O. D. Gordan, et al. "Surface- and tip-enhanced resonant Raman scattering from CdSe nanocrystals." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-161500.
Анотація:
Surface- and tip-enhanced resonant Raman scattering (resonant SERS and TERS) by optical phonons in a monolayer of CdSe quantum dots (QDs) is demonstrated. The SERS enhancement was achieved by employing plasmonically active substrates consisting of gold arrays with varying nanocluster diameters prepared by electron-beam lithography. The magnitude of the SERS enhancement depends on the localized surface plasmon resonance (LSPR) energy, which is determined by the structural parameters. The LSPR positions as a function of nanocluster diameter were experimentally determined from spectroscopic micro-ellipsometry, and compared to numerical simulations showing good qualitative agreement. The monolayer of CdSe QDs was deposited by the Langmuir–Blodgett-based technique on the SERS substrates. By tuning the excitation energy close to the band gap of the CdSe QDs and to the LSPR energy, resonant SERS by longitudinal optical (LO) phonons of CdSe QDs was realized. A SERS enhancement factor of 2 × 103 was achieved. This allowed the detection of higher order LO modes of CdSe QDs, evidencing the high crystalline quality of QDs. The dependence of LO phonon mode intensity on the size of Au nanoclusters reveals a resonant character, suggesting that the electromagnetic mechanism of the SERS enhancement is dominant. Finally, the resonant TERS spectrum from CdSe QDs was obtained using electrochemically etched gold tips providing an enhancement on the order of 104. This is an important step towards the detection of the phonon spectrum from a single QDDieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
31
Willner, Marjorie Rose. "Environmental Analysis at the Nanoscale: From Sensor Development to Full Scale Data Processing." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/94644.
Анотація:
Raman spectroscopy is an extremely versatile technique with molecular sensitivity and fingerprint specificity. However, the translation of this tool into a deployable technology has been stymied by irreproducibility in sample preparation and the lack of complex data analysis tools. In this dissertation, a droplet microfluidic platform was prototyped to address both sample-to-sample variation and to introduce a level of quantitation to surface enhanced Raman spectroscopy (SERS). Shifting the SERS workflow from a cell-to-cell mapping routine to the mapping of tens to hundreds of cells demanded the development of an automated processing tool to perform basic SERS analyses such as baseline correction, peak feature selection, and SERS map generation. The analysis tool was subsequently expanded for use with a multitude of diverse SERS applications. Specifically, a two-dimensional SERS assay for the detection of sialic acid residues on the cell membrane was translated into a live cell assay by utilizing a droplet microfluidic device. Combining single-cell encapsulation with a chamber array to hold and immobilize droplets allowed for the interrogation of hundreds of droplets. Our novel application of computer vision algorithms to SERS maps revealed that sialic sugars on cancer cell membranes are found in small clusters, or islands, and that these islands typically occupy less than 30% of the cell surface area. Employing an opportunistic mindset for the application of the data processing platform, a number of smaller projects were pursued. Biodegradable aliphatic-aromatic copolyesters with varying aromatic content were characterized using Raman spectroscopy and principal component analysis (PCA). The six different samples could successfully be distinguished from one another and the tool was able to identify spectral feature changes resulting from an increasing number of aryl esters. Uniquely, PCA was performed on the 3,125 spectra collected from each sample to investigate point-to-point heterogeneities. A third set of projects evaluated the ability of the data processing tool to calculate spectral ratios in an automated fashion and were exploited for use with nano-pH probes and Rayleigh hot-spot normalization.Ph. D.
32
Coyle, Candace Mikki. "Surface-enhanced Raman spectroscopic studies of organonitriles on copper colloids." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=919.
Анотація:
Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xvii, 169 p. : ill. Vita. Includes abstract. Includes bibliographical references.
33
Liu, Jing. "Systematic studies of protein immobilization by surface plasmon field-enhanced fluorescence spectroscopy." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975928848.
34
Doherty, Matthew David. "Plasmonic nano-antenna arrays for surface enhanced Raman spectroscopy and other applications." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601361.
Анотація:
On sub-wavelength scales, photon-matter interactions are limited by diffraction. Electromagnetic radiation propagating in free space - or far-field radiation - can be coupled into the surface plasmonpolaritons of nanostructured metallic surfaces in order to overcome this limitation. The distribution of electromagnetic energy in the near-field of these structures can be controlled by altering their geometry, dielectric environment and composition. Hence, surface plasmon polaritons allow electromagnetic radiation to be effectively utilized and controlled on the nanoscale. In this thesis a detailed study of the complex relationship between the electromagnetic near-field and far-field responses of 'real' nanostructured metallic surfaces is presented. The near-field and far-field responses are specified in terms of surface enhanced Raman scattering enhancement factor (SERS EF) spectra and optical extinction respectively. First, it is shown that in the far-field gold nanorod and nanotube array substrates exhibit two distinct localized surface plasmon-polariton resonances (LSPRs): a longitudinal and transverse mode. These modes are demonstrated both experimentally and theoretically, and a potential application of gold nanorod substrates as ultrathin absorbers is outlined. The near-field properties of these arrays are then studied, revealing the existence of a third type of LSPR: the cavity mode. The presence of this mode is confirmed using a combination of SERS EF spectra, electron microscopy and electromagnetic modelling. The cavity mode simultaneously has the largest impact on the near-field behaviour (as observed through the SERS EF) and the weakest optical interaction: it has a "near-field type" character. Conversely, the transverse and longitudinal modes have a significant impact on the far-field behaviour, but very little impact on SERS: they have a "far-field type" character. Based on this understanding of the contrasting character of the three LSPRs there follows a clear illustration and explanation of the non-correlation between the SERS EF spectra and the optical response, and some key consequences of this are described and demonstrated
35
Sirimuthu, Narayana M. S. "Increasing the range and reproducibility of quantitative surface-enhanced Raman spectroscopy (SERS)." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431477.
36
Mallinder, Benjamin. "Detection of deoxyribonucleic acid by surface enhanced resonance Raman scattering spectroscopy (SERRS)." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248771.
37
Frano, Kristen A. "Surface-Enhanced Raman and Single-Molecule Spectroscopy Studies of Fugitive Artists' Pigments." W&M ScholarWorks, 2015. https://scholarworks.wm.edu/etd/1539791830.
38
Carneiro, Leandro de Bispo. "Detecção do peptídeo p17 (HIV) baseado em SERS (Surface-enhanced Raman Spectroscopy) /." Araraquara, 2015. http://hdl.handle.net/11449/138424.
Анотація:
Orientador: Sidney José Lima RibeiroBanca: Marcelo Nalin
Banca: Antonio Aparecido Pupim Ferreira
Banca: Gustavo Fernandes Souza Andrade
Banca: Airton Abrahan Martin
Resumo: A espectroscopia de Raman intensificada por superfície (SERS, termo em inglês Surfaceenhanced Raman Spectroscopy) é uma técnica promissora que mostra a sensibilidade para a detecção da interação de biomoléculas que são importantes para detecção precoce de doenças. O vírus da imunodeficiência humana (HIV) têm sido um grande problema por várias décadas. Existem vários métodos de deteção baseados na interação específica de anticorpos, tais como, o ELISA e os testes rápidos (TR's). No entanto, novas estratégias têm sido desenvolvidas para rápido diagnóstico do vírus HIV, e uma prova de conceito de detecção do peptídeo p17-1 foi descrito neste trabalho. A proteina matriz p17 é uma essencial proteína no ciclo de replicação do vírus HIV. As fases iniciais da replicação do vírus envolve a pré integração do complexo do DNA no núcleo do p17 desempenhando um papel na ligação de RNA viral e transporte para a membrana. Neste trabalho foram descritos duas plataformas SERS para a detecção do vírus HIV baseado no peptide p17 -1 (sequência LSGGELDRWEKIRLPGG). O anticorpo foi imobilizado em um substrato de ouro usando duas diferentes camadas automontadas (SAM). A primeira SAM, os substratos de ouro foram imersos em uma solução aquosa de 11 mercaptoundecanóico (MUA). Na segunda SAM, os substratos foram imersos em uma mistura aquosa de politietileno glicol (SHPEG- COOH e SH-PEG-CH3). Aqui serão chamados de SAM-MUA e SAM-PEG, respectivamente. Ambas as SAM's foram imersas emu ma solução de anticorpo (anti-p17) e foram descritas como plataforma d captura MUA e PEG. Ambas plataformas foram funcionalizadas com o peptídeo p17-1. Sondas SERS foram preparadas com nanopartículas de ouro e revestidas com uma molécula Raman reporter (azul de Nilo A) e funcionalizadas com um anticorpo anti-p17. Estas estruturas (sonda SERS e plataformas de captura) formam um ensaio sanduíche...
Abstract: Surface-enhanced Raman Scattering (SERS) technique offers great promises for simplified and sensitive detection of biomolecular interactions that are relevant for early disease diagnostics. Human immunodeficiency virus (HIV) has been a problem for decades. There are several methods of diagnostics based on antibodies specific reactions, such as enzyme-linked immunosorbent assays (ELISAs) and rapid test (RT). However, new strategies have been developed for rapid HIV diagnostics and, as a proof-of-concept, peptide p17-1 was considered here. The matrix protein p17 is a structural protein that is essential in the life cycle of the retrovirus The early stages of the virus replication involve the pre integration of the DNA complex into the nucleus P17 plays a role in RNA viral binding and transport to the membrane. Here were describe two new SERS platform for HIV detection based on peptide p17-1 (sequence LSGGELDRWEKIRLPGG). The antibody anti-p17 was immobilized in a planar gold surface using two differents self-assembled (SAM) techniques. First SAM, were obtained by immersion of the surface into ethanolic solution of 11-Mercaptoundecanoic acid (MUA). Second SAM were obtained by immersion in aqueous solution aquous mixtures of (SH-PEG-COOH/SH-PEG-CH3) and polyethylene glycol (PEG,). Here were describe the two platforms as SAM-MUA and SAMPEG, respectively. Both SAM's were immersed in a solution containing the anti-p17. Samples at this step were called capture platform-MUA and capture platform-PEG. Both capture platforms were funcionalizated with the peptide p17-1. SERS probes were prepared with gold nanoparticles coated with a Raman reporter molecule (Nile Blue A) and, functionalized with an anti-p17. These structures (SERS probe and capture platforms) allow for a sandwich assay, a strategy regularly used for high-sensitivity detection. The light blue color in the SERS mapping represents peptide strong...
Doutor
39
Ohlhaver, Christopher M. "Use of Surface Enhanced Raman Spectroscopy for the Detection of Bioactive Lipids." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5551.
Анотація:
The detection and analysis of lipids in biological matrices for clinical applications poses many challenges, but rapid and reliable detection will prove invaluable for clinical diagnosis. Herein, we report the application of drop-casted Ag nanoplatelets as surface enhanced Raman scattering (SERS) substrates for qualitative detection of 20-hydroxyeicosatetraenoic acid (20-HETE), which is a potential biomarker for diagnosis of hypertensive disorders. Biomarker peaks of 20-HETE can be reliably detected and differentiated from those of the structurally similar lipids (arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid) commonly found in human blood, even 1 pM concentrations. Additionally, one study mixed 20-HETE with three structurally similar lipids at concentrations several orders of magnitude greater than the target lipid and 20-HETE could still be detected under these conditions. These experiments demonstrate the viability of SERS for the rapid and reliable detection of endogenous bioactive lipids, which has significant clinical impact in enabling point of care diagnostics.
40
Boddu, Naresh K. "Trace Analysis of Biological Compounds by Surface Enhanced Raman Scattering (SERS) Spectroscopy." Youngstown State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1229542206.
41
De, Jesus Jenny Padua. "HEAVY METAL DETECTION IN AQUEOUS ENVIRONMENTS USING SURFACE ENHANCED RAMAN SPECTROSCOPY (SERS)." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1513185193940902.
42
Papadopoulou, Evanthia. "Detection of DNA components and DNA sequences by surface-enhanced Raman spectroscopy." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546409.
43
White, Daniel Joshua. "Nanostructured optical fibre for use as miniature surface-enhanced raman scattering sensors." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/42062.
Анотація:
Thesis (PhD) - Swinburne University of Technology, Centre for Atom Optics and Ultrafast Spectroscopy, 2007.Thesis submitted in fulfilment for the degree of Doctor of Philosophy, Centre for Atom Optics and Ultrafast Spectroscopy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Bibliography: p. 151-160.
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Hu, Yuan [Verfasser]. "Surface-Enhanced Infrared Attenuated Total Reflection Spectroscopy based on Carbon Nanomaterials / Yuan Hu." Ulm : Universität Ulm, 2019. http://d-nb.info/1192373251/34.
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Baumann, Axel [Verfasser]. "Studies on membrane protein folding by surface enhanced infrared absorption spectroscopy / Axel Baumann." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1159900612/34.
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Sutton, C. P. "Application of surface enhanced raman spectroscopy to measurements of diffusion through silastic membranes." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342271.
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Lin, Yung-Chun. "Electrochemical surface enhanced Raman spectroscopy of a beacon probe immobilized on Au electrodes." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/422134/.
Анотація:
The aim of this thesis is to investigate the factors, and possible mechanisms, involved in the electrochemical SER response of a reporter dye attached to an immobilized oligonucleotide on the negatively charged Au surface. This work used a 5’-thiol anchored beacon and a partial self-pairing oligonucleotide, instead of a linear strand probe, to study the sensing process. The observation of the SERS intensity of the 3’-labelled dye at the negatively charged Au surface is similar to that of the hybridized duplex of the linear probe at low surface coverage. By competitive adsorption of mercaptohexanol together with the beacon probe in the immobilization solution, 3 times lower coverage than reported previously was achieved to ensure low intramolecular interactions between the beacon probe. A number of electrochemical methods were also utilized to observe the Raman intensity of the Texas Red-labelled beacon probe and the results interpreted in terms of the configuration changes of the beacon probe. The potential dependent Raman enhancement of the reporter itself, Texas Red, was later found to have a similar response to the labelled beacon probe. A detailed discussion with respect to absorption of the Texas Red, orientation, potential tuning of the LSPR, the interference from hydrogen evolution, the electronic Stark effect and the charge-transfer enhancement is presented, to understand the possible contributions to the potential dependence Raman enhancement. As a result, a molecule-to-metal charge-transfer mechanism was found to explain the most relevant dependence of the enhancement on electrode potential. The potential dependent Raman response of the corresponding beacon probe was compared as a function of the time scale of the modification, the alkyl chain length of mercaptoalkanol from C2, C4, C6 and C9 and the preparation method used (backfilling or co-adsorption). The possible surface states are proposed to explain the electrochemical SERS response of the system.
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Rodriguez, Raul D., Evgeniya Sheremet, Tanja Deckert-Gaudig, Corinne Chaneac, Michael Hietschold, Volker Deckert, and Dietrich R. T. Zahn. "Surface- and tip-enhanced Raman spectroscopy reveals spin-waves in iron oxide nanoparticles." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-168045.
Анотація:
Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm−1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal–nanoparticle interaction and the strongly localized electromagnetic field contribute to the appearance of this mode. The localized excitation that generates this mode is confirmed by tip-enhanced Raman spectroscopy (TERS). The appearance of the spin-waves only when the TERS tip is in close proximity to a nanocrystal edge suggests that the coupling of a localized plasmon with spin-waves arises due to broken symmetry at the nanoparticle border and the additional electric field confinement. Beyond phonon confinement effects previously reported in similar systems, this work offers significant insights on the plasmon-assisted generation and detection of spin-waves optically inducedDieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Gullekson, Corinne. "Surface enhanced Raman spectroscopy of collagen I fibrils." 2011. http://hdl.handle.net/10222/14026.
Анотація:
Collagen fibrils are the main constituent of the extracellular matrix surrounding eukaryotic cells. Even though the assembly and structure of collagen fibrils is well characterized, very little is known about the physico-chemical properties of their surface which is one of the key determinants of their biological functions. One way to obtain surface sensitive structural and chemical data is to take advantage of the near field nature of surface and tip-enhanced Raman spectroscopy. Using Ag and Au nanoparticles bound to collagen type I fibrils, as well as tips coated with a Ag nanoparticles and a thin layer of Ag, we obtained Raman spectra characteristic of the first layer of collagen molecules at the surface of the fibrils. The most frequent Raman peaks were attributed to aromatic residues such as phenylalanine and tyrosine. We also observed in several instances Amide I bands with a full width at half maximum of 10-30 cm-1. The assignment of these Amide I bands positions suggests the presence of collagen-helices as well as alpha-helices and beta-sheets at the fibril’s surface. As a step towards in vivo characterization of collagen fibrils, fascicles removed from tendons were also examined with surface-enhanced Raman spectroscopy.
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Liao, Tzu-Yi, and 廖子頤. "Human Blood Diagnostic by Surface Enhanced Raman Spectroscopy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/73972244522240363517.
Анотація:
碩士國立臺灣海洋大學
光電科學研究所
98
In this thesis, we present the studies of using surface enhanced Raman spectroscopy (SERS) to measure and analyze the glucose concentration in human blood. Our method is based on the following procedures: (1) High-aspect nanochannels of anodic aluminum oxide (AAO) substrates are used to filter blood cells and large biomolecules in whole blood sample. The 200nm-diameter and 200m-long AAO channels can filter the blood and exclude the interference of fluorescence and other complicated Raman signals of large proteins. (2) The filtered blood sample is then covered on the backside of the AAO substrate, which is coated with a nanometer thickness of silver film. The silver coated AAO surface provides metallic nanostructures that can greatly enhance the Raman signals of the filtered blood due to the SERS effect. In this method, only several micro-liters of the blood sample is required. This quantity is suitable for obtaining blood samples from the blood collection needle. With few blood amounts and the AAO-SERS substrate, we got different Raman intensities from different thickness of silver and gold nanostructures by using a 780 nm laser. The optimal condition for SERS on a 200-nm-diameter AAO substrate is silver film with 10 nm thickness. We confirmed that the SERS signals at 1133cm-1 and 494cm-1 can be used to indicate the glucose concentrations. We found positive correlation between the change of SERS signals and the concentration of glucose. The detectable glucose concentration is in the range between 60mg/dl to 360mg/dl, which is suitable for the point-of-care application of the diabetic. From the measurement, we also found that SERS signals were strongly dependent on the preservation of the blood samples. The Raman signal at 725cm-1 which is related to the Adenine was greatly affected by the preservation ways of blood samples. For room-temperature preservation, the 725cm-1 peak significantly increased with time. For 4oC condition, the change of 725cm-1 peak was small. This 725cm-1 SERS peak may be used to indicate the healthy condition of the blood sample.