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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.
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Farazkhorasani, Fatemeh. "Raman and SERS studies of filamentous fungi." Royal Society of Chemistry, 2012. http://hdl.handle.net/1993/23855.
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Fungal species perform many important roles in biotechnology and recycling and act as agents of disease and decay. Surface-enhanced Raman scattering (SERS) has attracted significant attention as an analytical method for chemical and biological identification. For SERS experiments, it is essential to generate gold nanoparticles (AuNPs) with proper sizes and shapes. Raman and SERS imaging of fungi via in vivo synthesis of AuNPs were used to explore cellular components of Aspergillus nidulans (A. nidulans) cell. Critical parameters including pH, temperature and metal concentration affect the sizes and shapes of the NPs. For better control of NP formation (size, shape and location), pre-formed NP were incubated with A. nidulans colonies. Aspergillus nidulans outer hyphal walls were coated with NPs. Raman and SERS imaging of fungal walls revealed that proteins, carbohydrates and lipids are the main constituents of fungal cell wall.October 2014
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Gühlke, Marina. "Oberflächenverstärkte Hyper-Raman-Streuung (SEHRS) und oberflächenverstärkte Raman-Streuung (SERS) für analytische Anwendungen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17570.
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Hyper-Raman-Streuung folgt anderen Symmetrieauswahlregeln als Raman-Streuung und profitiert als nicht-linearer Zweiphotonenprozess noch mehr von verstärkten elektromagnetischen Feldern an der Oberfläche plasmonischer Nanostrukturen. Damit könnte die oberflächenverstärkte Hyper-Raman-Streuung (SEHRS) praktische Bedeutung in der Spektroskopie erlangen. Durch die Kombination von SEHRS und oberflächenverstärkter Raman-Streuung (SERS) können komplementäre Strukturinformationen erhalten werden. Diese eignen sich aufgrund der Lokalisierung der Verstärkung auf die unmittelbare Umgebung der Nanostrukturen besonders für die Charakterisierung der Wechselwirkung zwischen Molekülen und Metalloberflächen. Ziel dieser Arbeit war es, ein tieferes Verständnis des SEHRS-Effekts zu erlangen und dessen Anwendbarkeit für analytische Fragestellungen einzuschätzen. Dazu wurden SEHRS-Experimente mit Anregung bei 1064 nm und SERS-Experimente mit Anregung bei derselben Wellenlänge sowie mit Anregung bei 532 nm - für eine Detektion von SEHRS und SERS im gleichen Spektralbereich - durchgeführt. Als Beispiel für nicht-resonante Anregung wurden die vom pH-Wert abhängigen SEHRS- und SERS-Spektren von para-Mercaptobenzoesäure untersucht. Mit diesen Spektren wurde die Wechselwirkung verschiedener Silbernanostrukturen mit den Molekülen charakterisiert. Anhand von beta-Carotin wurden Einflüsse von Resonanzverstärkung im SEHRS-Experiment durch die gleichzeitige Anregung eines molekularen elektronischen Übergangs untersucht. Dabei wurde durch eine Thiolfunktionalisierung des Carotins eine intensivere Wechselwirkung mit der Silberoberfläche erzielt, sodass nicht nur resonante SEHRS- und SERS-Spektren, sondern auch nicht-resonante SERS-Spektren von Carotin erhalten werden konnten. Die Anwendbarkeit von SEHRS für hyperspektrale Kartierung in Verbindung mit Mikrospektroskopie wurde durch die Untersuchung von Verteilungen verschiedener Farbstoffe auf strukturierten plasmonischen Oberflächen demonstriert.Hyper-Raman scattering follows different symmetry selection rules than Raman scattering and, as a non-linear two-photon process, profits even more than Raman scattering from enhanced electromagnetic fields at the surface of plasmonic nanostructures. Surface-enhanced hyper-Raman scattering (SEHRS) could thus gain practical importance for spectroscopy. The combination of SEHRS and surface-enhanced Raman scattering (SERS) offers complementary structural information. Specifically, due to the localization of the enhancement to the close proximity of the nanostructures, this information can be utilized for the characterization of the interaction between molecules and metal surfaces. The aim of this work was to increase the understanding of the SEHRS effect and to assess its applicability to answer analytical questions. For that purpose, SEHRS experiments with excitation at 1064 nm and SERS experiments with excitation at the same wavelength, as well as with excitation at 532 nm - to detect SEHRS and SERS in the same spectral region - were conducted. As an example for non-resonant excitation, pH-dependent SEHRS and SERS spectra of para-mercaptobenzoic acid were examined. Based on these spectra, the interaction of different silver nanostructures with the molecules was characterized. beta-Carotene was used to study the influence of resonance enhancement by the excitation of a molecular electronic transition during SEHRS experiments. By the thiol-functionalization of carotene, a more intense interaction with the silver surface was achieved, which enables to obtain not only resonant SEHRS and SERS but also non-resonant SERS spectra of carotene. Hyperspectral SEHRS imaging in combination with microspectroscopy was demonstrated by analyzing the distribution of different dyes on structured plasmonic surfaces.
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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.
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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.
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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.
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Noonan, Jonathan. "Surfaced enhanced Raman spectroscopy (SERS) for the molecular imaging of atherosclerosis." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/8939/.
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Cardiovascular diseases are the leading cause of mortality worldwide, with the majority of these deaths being a result of the inflammatory pathology, atherosclerosis. A critical need for multi-parameter molecular imaging has been identified to facilitate improved atherosclerosis diagnosis and the understanding of local inflammatory pathways in humans. Established imaging modalities such as ultrasound and magnetic resonance imaging are being investigated as potential solutions to this clinical problem, however, inherent limitations with these technologies have resulted in the exploration of alternate imaging approaches. This thesis focuses on the development and testing of surface enhanced Raman spectroscopy (SERS), a promising and novel molecular imaging modality, for the molecular imaging of vascular inflammatory biomarkers in vitro, ex vivo and in vivo. SERS detects molecule specific vibrational signals which are enhanced when an analyte is excited with light in close proximity to a noble metal surface. To achieve molecular specificity and surface enhancement, we developed antibody functionalised gold nanoparticles (nanotags) designed to bind to our molecular targets of interest, the adhesion molecules, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and P-selectin, and produce a SERS signal detectable by spectroscopy and/or microscopy based approaches. In vitro, we demonstrate the simultaneous and quantifiable SERS detection of ICAM-1, VCAM-1 and P-selectin on TNFa stimulated human endothelial cells. We subsequently demonstrated the simultaneous SERS detection of ICAM-1, VCAM-1 and P-selectin in freshly isolated atherosclerotic human coronary artery ex vivo. Finally, we explored SERS imaging in a humanised mouse model, demonstrating non-invasive multiplex imaging of adhesion molecules in vivo. In summary, this proof of concept study demonstrates the suitability of SERS and nanotags for the non-invasive molecular imaging of vascular inflammation. We have tested this approach with increasing biological complexity and highlighted SERS as a potential molecular imaging tool for future clinical translation in the context of vascular inflammation, atherosclerosis and cardiovascular disease.
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Marotta, Nicole Ella. "Patterned nanoarray sers substrates for pathogen detection." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37274.
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The objectives of the work presented were to 1) fabricate reproducible nanorod array SERS substrates, 2) detection of bacteria using nanorod substrates, 3) detection of DNA hybridization using nanorod substrates and 4) critically evaluate the sensing method.
Important findings from this work are as follows. A novel method for batch fabrication of substrates for surface enhanced Raman scattering (SERS) has been developed using a modified platen machined to fit in a commercial electron beam evaporator. The use of this holder enables simultaneous deposition of silver nanorod (AgNR) arrays onto six microscope slide substrates utilizing glancing angle deposition. In addition to multiple substrate fabrication, patterning of the AgNR substrates with 36 wells allows for physical isolation of low volume samples. The well-to-well, slide-to-slide, and batch-to-batch variability in both physical characteristics and SERS response of substrates prepared via this method was nominal. A critical issue in the continued development of AgNR substrates is their stability over time, and the potential impact on the SERS response. The thermal stability of the arrays was investigated and changes in surface morphology were evaluated using scanning electron microscopy and x-ray diffraction and correlated with changes in SERS enhancement. The findings suggest that the shelf-life of AgNR arrays is limited by migration of silver on the surface. Continued characterization of the AgNR arrays was carried out using fluorescent polystyrene microspheres of two different sizes. Theory suggests that enhancement between nanorods would be significantly greater than at the tops due to contributing electromagnetic fields from each nanostructure. In contrast to the theory, SERS response of microspheres confined to the tops of the AgNR array was significantly greater than that for beads located within the array. The location of the microspheres was established using optical fluorescence and scanning electron microscopy.
The application of SERS to characterizing pathogens such as bacteria and viruses is an active area of investigation. AgNR array-based SERS substrates have enabled detection of pathogens present in biofluids. Specifically, several publications have focused on determining the spectral bands characteristic of bacteria from different species and cell lines. Studies were carried out on three strains of bacteria as well as the medium in which the bacteria were grown. The spectra of the bacteria and medium were surprisingly similar, so additional spectra were acquired for commonly used bacterial growth media. In many instances, these spectra were similar to published spectra purportedly characteristic of specific bacterial species.
In addition to bacterial samples, nucleic acid hybridization assays were investigated. Oligonucleotide pairs specifically designed to detect respiratory syncytial virus (RSV) in nasal fluids were prepared and evaluated. SERS spectra acquired on oligos, alone or in combination, contain the known spectral signatures of the nucleosides that comprise the oligo. However, spectra acquired on an oligo with a 5'- or 3' thiol were distinctly different from that acquired on the identical oligo without a thiol pendant group suggesting some control over the orientation of the oligo on the nanorod surface. The signal enhancement in SERS depends markedly upon the location of the probe relative to the substrate surface. By systematic placement of nucleotide markers along the oligo chain, the point at which the nucleotide disappears from the spectrum was identified.
The overall findings for AgNR SERS substrates suggest that the applicability of SERS for detecting nucleic acid hybridization is limited. The strong distance dependence coupled with the lack of substrate stability at temperatures required for annealing oligos during hybridization suggest that AgNRs are not the platform to use for hybridization assays.
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Gant, Virgil Alexander. "Detection of integrins using surface enhanced raman spectroscopy." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2304.
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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.
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Ochsenkühn, Michael Andreas. "Modern Raman spectroscopy for investigation of host-pathogen interactions." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4760.
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Biomedical sciences are in need of more versatile and more sensitive approaches for research and also for diagnostic purposes. In particular, intracellular detection and imaging of disease relevant proteins is a challenge. Although the state of the art method of intracellular imaging is fluorescence, it suffers from several drawbacks. Raman is an alternative imaging modality and this work investigates the use of different Raman techniques for detection and imaging of cellular constituents. In one aspect of the work, surface-enhanced Raman spectroscopy using gold nanoshells excitable at a wavelength of 780 nm was investigated. Initially the investigation of the uptake of the 150 nm diameter nanoparticles showed that NS are taken up voluntarily by a non-standard en- docytosis mechanism into mammalian fibroblast cells. Furthermore it was shown that internalized particles have no detrimental in uence on cell growth or cell viability. That these nanoparticles are non toxic was further confirmed by testing for markers of apoptosis and necrosis. Preliminary surface-enhanced Raman spectroscopy (SERS) studies produced spectra from intracellular compartments with an enhancement factor of 1010. To yield high specificity of the intracellular Raman protein sensor, two different approaches were studied. The first is based on the application of DNA aptamers which form a stacked G-quadruplex on target protein binding. A SERS sensor based on the well characterized Thrombin binding aptamer (TBA) yielded high reproducibility, high target specificity, and a limit of detection down to 0.1 fM. Further studies on a similar stacked G-quadruplex forming aptamer confirmed that observed detection signal is produced by the aptamer assuming its secondary structure but also showed that the stabilization and formation of the G-quadruplex secondary structure is strongly buffer dependent. A second sensing approach was based on a peptide (a3(IV)NC1) influential in Goodpasture's syndrome, an autoimmune disease. With the help of this peptide we found that an intracellular redoxpotential of -200 mV is necessary to make it accessible for the protease Cathepsin D. We found that SERS sensing has the ability to study the binding of Cathepsin D, its activity and with the help of a synthesized amino-acid SERS library the direct detection of the remaining peptide products. Finally this work concludes with imaging the changes of lipid droplet structure and distribution in fibroblast cells during the infection process of the murine cytomegalovirus (MCMV) in fixed and in living cells by coherent anti-Stokes Raman based on a Synchro-lock phase coupled setup. This showed that CARS imaging is able to non-invasively investigate the changes of lipid structures during different stages of the infection process and therefore promises to be a valuable tool in biological research.
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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.
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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.
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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.
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Carneiro, Leandro de Bispo. "Detecção do peptídeo p17 (HIV) baseado em SERS (Surface-enhanced Raman Spectroscopy) /." Araraquara, 2015. http://hdl.handle.net/11449/138424.
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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...
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Ray, Bryan Hubert. "SERS analysis of biological analytes using an azo tether." Laramie, Wyo. : University of Wyoming, 2005. http://proquest.umi.com/pqdweb?did=1095427621&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Tsoutsi, Dionysia. "Inorganic Ions Sensing by surface-enhanced Raman scattering spectroscopy." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/288213.
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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.
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Halvorson, Rebecca Ann. "Raman Spectroscopy for Monitoring of Microcystins in Water." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/76924.
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Cyanobacterial blooms are of great concern to the drinking water treatment industry due to their capacity to produce microcystins and other cyanotoxins that are deadly to humans, livestock, pets, and aquatic life at low doses. Unfortunately, the strategies currently employed for cyanotoxin detection involve laborious analyses requiring significant expertise or bioassay kits that are subject to numerous false positives and negatives. These methods are incapable of providing rapid, inexpensive, and robust information to differentiate between the >80 cyanotoxin variants potentially present in an aqueous sample.
The use of Raman spectroscopy for identification and quantification of the ubiquitous cyanotoxin microcystin-LR (MC-LR) was examined. Raman spectra readily reflect minute changes in molecular structure, spectra can be collected through water or glass, portable Raman spectrometers are increasingly available, and through surface enhanced Raman spectroscopy (SERS) it is possible to achieve femto or picomolar detection limits for a variety of target species. Drop coating deposition Raman (DCDR) was successfully implemented for quantitation of 2-100 ng of MC-LR deposited in 2 ?L of aqueous sample, even without the use of a specifically designed DCDR substrate or Raman signal enhancements. Reproducible MC-LR Raman spectra were observed for both fresh and aged DCDR samples, and the MC-LR Raman spectrum remained identifiable through a matrix of >80% DOM by mass. DCDR methods show tremendous potential for the rapid, simple, and economical detection of cyanotoxins in environmental matricies at environmentally relevant concentrations.Master of Science
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Zhou, Yan. "Synthesis, Characterization and Application of SERS-active Metal Nanoparticles." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458644099.
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Carella, Yvonne. "Development of SERS for the determination of environmental pollutants." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288745.
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Sant\'Ana, Antonio Carlos. "Caracterização da 2,2\':6\',2\" - terpiridina adsorvida sobre superfície de prata, através da técnica SERS (Surface Enhanced Raman Spectroscopy)." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-16102007-110432/.
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Monocamadas auto-organizadas da 2,2\':6\' ,2\" -terpiridina formadas sobre a superficie do eletrodo de Ag e Cu foram caracterizadas através da técnica SERS (Surface Enhanced Raman Spectroscopy) em experimentos ex situ e in situ. Foram estudadas alterações nas espécies adsorvidas em função da natureza das soluções-mãe e das soluções eletrolíticas utilizadas, tais como, solvente, pH da solução, ânion-suporte e a presença de outro adsorbato orgânico: a 2-mercaptopirimidina (mpy). Para estudar-se a adsorção da tpy foram obtidos padrões espectrais em que a molécula realiza diferentes interações com a vizinhança: no estado sólido, em solução, fundida e formando complexos com os íons CU2+ e Ag+. Também foram obtidos padrões para o ânion Cl04- coordenado ao CU2+, possibilitando explicar a adsorção deste ânion à superficie. Os resultados indicam que a tpy adsorve sobre a superficie metálica através de seus átomos de nitrogênio formando complexos de superficie do tipo I e do tipo II, nos quais assume uma conformação cis-cis. A tpy protonada, preferencialmente, perde o próton para adsorver sobre o eletrodo. Em experimentos in situ, quando potenciais mais negativos são aplicados, a tpy adsorve sobre a superfície metálica em uma posição próxima à horizontal através dos elétrons π dos anéis piridínicos. Na presença da mpy a tpy adsorve horizontalmente sobre a superfície do eletrodo, não ocorrendo sua coordenação com o metal. Estudos da adsorção do composto 4\'-(5-mercaptopentil)-2,2\':6\',2\" - terpiridina (tpy-SH) sobre eletrodo de Ag indicam que a molécula adsorve através do átomo de enxofre sem que ocorra interação entre os átomos de nitrogênio da parte tpy e a superficie metálica. Isto foi confirmado pela coordenação do cátion CU2+ com a parte tpy das moléculas tpy-SH adsorvidas, bem como pela intensificação das bandas atribuídas à parte alcano-tiol da molécula devido sua proximidade com a superficie. Os estudos do complexo [Cu(II)tpyH2OCl04]Cl04 mostram que a exposição à radiação excitante produz a perda da coordenação da água ao íon metálico com o ânion Cl04- passando a coordenar por dois átomos de oxigênio. O perfil de excitação deste complexo foi realizado e constatou-se pré-ressonância do sinal Raman com a transição eletrônica da molécula na região entre 300 e 350 nm. Ao ser adsorvido sobre a superficie do eletrodo este complexo sofre redução e a tpy coordena aos átomos metálicos do eletrodo formando um complexo de superficie.Self-assembly monolayers of 2,2\':6\',2\" - terpyridine (tpy) were grown on Ag and Cu electrode surface and studied ex situ and in situ by SERS (Surface Enhanced Raman Spectroscopy). The nature of the adsorbate species was studied as a function of the mother-sulution changing solvent, pH and supporting-anion. The effect of 2-mercaptopyrimidine (mpy) as co-adsorbate was also investigated. For comparison purposes the Raman spectrum of tpy was obtained as solid, solution, molten and as Ag+ and CU2+ complexes. A supplementary Raman study of CU2+ perchlorates was also performed to facilitate the understanding of the Cl04- adsorption on the metal surface. The results showed that tpy adsorb on the metallic surface through the nitrogen atoms forming two different surface complexes (type I and type II) that have cis-cis conformation. Protonated tpy, preferentially, loses the proton to adsorb on the electrode. In the in situ experiments, when more negative potentials were applied, the observed spectral changes were ascribed to a modification in the adsorption geometry leading to a nearly flat arrangement. In presence of mpy, tpy adsorbs flat on the electrode surface and coordination with the metal is not observed. Studies on the adsorption of the 4\'-(5-mercaptopentyl)-2,2\':6\',2\"-terpyridine (tpy-SH) on Ag electrode showed that the molecule adsorb through the sulfur atom and there is no interaction between the nitrogen atoms of tpy moiety and the metal. This was confirmed by coordination of CU2+ with the tpy moiety of adsorbed tpy-SH molecules and by the enhancement of the alkyl-thiol bands which are close to the surface. Studies of the [Cu(II)tpyH2OCl04]Cl04 complex showed that depending on the energy density used the exciting radiation may cause the release of the coordinated water, leading to a bidentate coordination of the Cl04- anion. The Raman excitation profile for this complex was obtained and pre-resonance enhancement associated with a transition between 300 e 350 nm was observed. When adsorbed on the electrode surface this complex undergoes reduction and the tpy coordinates to the metal atoms forming a surface complex.
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Touzalin, Thomas. "Tip-enhanced Raman spectroscopy on electrochemical systems." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS364.
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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
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Yang, Mingwei. "In Situ Arsenic Speciation using Surface-enhanced Raman Spectroscopy." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3387.
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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.
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SACCO, ALESSIO. "Metrological Approach to Tip-enhanced Raman Spectroscopy." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2827709.
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Lin, Sally S. B. Massachusetts Institute of Technology. "Investigation into the use of surface-enhanced Raman spectroscopy (SERS) for organic dye analysis." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98657.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 48-49).
In art conservation, color is essential to understanding a society's culture and history-as an indicator of beauty, status, religion, and more-but has a tendency to fade and diminish over time. Analytical techniques, particularly that of pigment identification, can reveal the artifact's original color and appearance and give new insights to an artist's intentions, techniques, date of creation, and more. However, most identification procedures are invasive and destroy the samples in the process. Surface-enhanced Raman spectroscopy (SERS) has recently been identified as a technique that is minimally invasive and also solves the issue of fluorescence that is found in many other techniques. In this paper, a specific SERS procedure has been developed for the identification of yellow organic dyes from 18th century Japanese Woodblock prints. Several SERS spectra of nine dyes both in solution and applied on artist paper have also been documented in hopes of assisting with pigment identification in the future.
by Sally Lin.
S.B.
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Madden, Odile Marguerite, and Odile Marguerite Madden. "Development of Vapor Sensors for Volatile Museum Contaminants by Surface Enhanced Raman Spectroscopy (SERS)." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/283712.
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Detection and identification of pesticide residues on objects of cultural heritage is a serious and urgent challenge that currently faces many museums, Native American communities, and private collections worldwide. Organic artifact materials, such as wood, animal hide, basketry, textiles, paper, horn and bone, have traditionally been treated with pesticides to eradicate and prevent infestation by insects, rodents, and mold. These poisonous substances can persist for years in the controlled environment of a museum storeroom and present a potential poisoning risk to people who come in contact with the objects. Surface-enhanced Raman spectroscopy (SERS) has the potential to detect volatile organic pesticides in this context. The technique can overcome the insensitivity of normal Raman spectroscopy and fluorescence interference, and make possible detection of many organic compounds in parts per million concentration. This investigation is aimed at evaluating SERS for the detection and identification of volatiles in museums, with emphasis on naphthalene vapor. The potential of several SERS-active materials; Tollens mirrors, gold film over nanosphere arrays, citrate-stabilized colloidal silver, and nanoporous gold; to detect Rhodamine B and naphthalene is investigated. The research also highlights the mechanisms that underlie SERS, and the relationship between substrate nanostructure and SERS performance.
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Mabbott, Samuel. "Optimisation of solid-state and solution-based SERS systems for use in the detection of analytes of chemical and biological significance." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/optimisation-of-solidstate-and-solutionbased-sers-systems-for-use-in-the-detection-of-analytes-of-chemical-and-biological-significance(de70094c-8da0-4326-bfb2-6adf00b86af9).html.
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Surface enhanced Raman scattering (SERS) has achieved much attention since its conception in 1974. The analytical technique overcomes many difficulties associated with conventional Raman whilst also increasing sensitivity. However, the increased interest and work in the field has also identified flaws, many of which are centred on the irreproducibility of the SERS enhancement effect. The majority of the work described in this thesis focusses on the ‘optimisation’ of solid-state and solution based SERS systems. Optimisation plays a crucial role in maximising both enhancement effects and reproducibility. Here criteria are outlined for the synthesis of high performance solid-state SERS substrates and the synthesis of a range of substrates is assessed, each with associated pros and cons. The most successful substrate was synthesised by exploiting redox potentials which allow for the direct deposition of silver onto copper foil. The deposition times and temperatures were optimised sequentially to generate a high performance substrate capable of detecting Rhodamine 6G at trace levels. Reproducibility comparisons of the silver on copper (SoC) substrate were carried out against commercial substrates: Klarite and QSERS, multiple univariate and multivariate methods were used to assess the substrates performance. The results confirmed that the SoC substrate performed better than both the commercial substrates. The work also highlights the importance of using multiple data analysis methods in order to assess the performance of a solid-state SERS substrate. Deposition of the silver surface was also successful on British 2p coins allowing the for the detection and discrimination of illegal and legal drugs when coupled with multivariate data analysis methods such as PCA and PLS. Solution based SERS analyses were also carried out successfully using different optimisation strategies. The initial investigation involved careful control of the individual components of a SERS system (nanoparticles, aggregating agents and analyte) in order to establish a low limit of detection for the increasingly abused ‘legal high’ MDAI. The use of a reduced factorial design was then successfully employed to explore a greater number of SERS variables and define a low limit of detection for the class B drug mephedrone. The robust experimental design also allowed an insight into the importance of each of the individual components within a solution based SERS system. The final piece of work carried out was the SERS discrimination of antibiotics: ampicillin, ticarcillin and carbenicillin. Optimisation of the solution based experiment allowed the in-situ hydrolysis of the β-lactam moiety present in ampicillin rendering it pharmacologically inactive to be followed under acidic conditions at concentrations of 10 ppm.
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Saffie, Jared C. "Microfluidic evaporator chip for concentration of bacterial samples for SERS identification." Thesis, Boston University, 2014. https://hdl.handle.net/2144/21248.
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Thesis (M.Sc.Eng.)Sepsis is a serious medical condition in which a person becomes infected with bacteria in his or her bloodstream. The symptoms of sepsis are a result of the immune system’s interaction with the infecting agent. Currently, to diagnose a patient with sepsis, a blood sample must be collected and cultured for 24-48 hours before the infection can be confirmed. In the meantime, a broad-scope antibiotic is administered which may or may not be effective in treating the patient. If the antibiotic is ineffective, a different antibiotic must be chosen. When the results of the blood culture are available, a narrow scope antibiotic, appropriate to treat the infection is administered. However, sepsis has a mortality rate of 18-30% depending on the infecting agent and the treatment is highly time sensitive. Within 24 hours, the syndrome may progress to septic shock and mortality rates reach 50%. Therefore, it is important to quickly and correctly identify the infecting agent and provide immediate targeted treatment. Surface Enhanced Raman Spectroscopy (SERS) can be used to quickly identify and distinguish between different bacterial strains; however it requires higher bacterial concentrations than are present in the blood during the early stages of sepsis. A microfluidic evaporator chip has been developed to concentrate bacteria samples from 4μl to 100nl; the chip has been evaluated for concentration efficiency on Escherichia coli and methicillin-sensitive Staphylococcus aureus. Various blocking methods using bovine serum albumin (BSA) have been tested to reduce bacterial adhesion to the chip and have improved bacterial recovery to around 70% for both strains tested. Ongoing tests are being performed to improve bacterial recovery and sample purity for identification.
2031-01-01
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Hugall, James T. "On the nature of SERS from plasmonic nanostructures." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/267496.
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The nature of surface-enhanced Raman scattering (SERS) on nanostructured surfaces is explored using both inorganic and organic-based systems and a variety of environmental perturbation mechanisms. Experimental optical characterisation systems are developed and existing systems extended to facilitate this exploration. SERS of inorganic semiconducting quantum dots (QDs) is observed for the first time, paving the way for their use as spatially well-defined SERS markers. Tuning of the Raman excitation wavelength allows comparison between resonance and nonresonance QD SERS and identifies enhancement due to the plasmonic nanostructure. A gentle mechano-chemical process (carbon dioxide snow jet) is used to rearrange adsorbed organic thiol monolayers on a gold plasmonic nanostructure. The necessity of nanoscale roughness to the large SERS enhancement on pit-like plasmonic nanostructures is shown and demonstrates a new method to boost SERS signals (> 500 %) on plasmonic nanostructures. A multiplexed time-varied exposure technique is developed to track this molecular movement over time and highlights the different origins of the SERS peak and its accompanying background continuum. Using low-temperature cryogenics (down to 10 K) the SERS peak and background continuum intensity are shown to increase as the plasmonic metal damping reduces with temperature. Temperature dependent measurements of QD (resonance) SERS are shown to have strong wavelength dependence due to the excitonic transitions in QDs. Changes to the QD fluorescence at low temperature allows striking comparison between the Raman and fluorescence processes. The role of charge transfer and electromagnetic enhancement in the SERS intensity of p-aminothiophenol (pATP) is investigated on nanostructured plasmonic surfaces coupled to metallic nanoparticles. The results support the importance of charge transfer effects to the SERS of pATP, and highlight the difference between those of electromagnetic origin. Addition of nanoparticles to the nanostructured surface was seen to enhance SERS signals by up to 100×.
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Muralidharan, Ranjani. "Investigation and characterization of Pt-modified Au catalysts and polymer composites by electrochemistry, Raman and surface enhanced Raman spectroscopy (SERS)." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5084.
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This dissertation thesis consists of six chapters. The main focus of this study is the need for understanding the reaction mechanism and intermediates formed on Pt-modified Au surface as anode catalysts in the formic acid fuel cells. Chapter 1 gives an introduction to formic acid and methanol fuel cells, an overview of the current catalysts employed at the anode of the fuel cells, specifically the Pt-modified Au electrodes as potential catalysts and the different deposition methods for preparing this catalytic surface. Information about different electrochemical methods used like cyclic voltammetry and potential step method along with other characterization methods and spectroscopic techniques has also been given. As one of the main methods to characterize the catalysts, Raman and surface enhanced Raman spectroscopy have been discussed in detail.
The electrooxidation of formic acid and the nature of the intermediates at a platinum-modified gold surface prepared through spontaneous deposition were characterized using a combination of electrochemistry and in situ surface enhanced Raman spectroscopy (SERS). Spontaneously deposited platinum on gold showed unique high catalytic activity for formic acid electrooxidation. The oxidation current of formic acid is more than five times higher on the Pt-modified gold electrode surface than on a bare Pt surface and about 72 times higher than on a bare Au surface. SERS results reveal the involvement of a novel HCOO− adsorbate at 300 cm−1. Both electrochemical and spectroscopic results suggest that the formic acid electrooxidation takes place by the dehydrogenation pathway involving a low frequency formate intermediate on the Pt-modified gold electrode catalyst. Next, the effect of the deposition solution employed in the spontaneous deposition process was explored and demonstrated to play an important role in catalytic activity of these surfaces. Electrochemical studies show that Pt-modified Au surfaces prepared from bromoplatinate solution are most active in oxidizing formic acid. The second most active surface for formic acid electrooxidation was that from chloroplatinate followed by that from the iodoplatinate solutions. Also, the optimal condition to prepare the most active surface is different for various haloplatinate solutions. In situ surface enhanced Raman spectroscopy (SERS) with potential control revealed the presence of formate at 300 cm-1 as the reaction intermediate in the catalytic processes on all three Pt-modified Au surfaces, but with different potential-dependent behaviors.
A clear and transparent bis ethylenedioxy tetrathiafulvalene iodine doped polymer films (BEDO-TTF) was successfully prepared by electrochemical method of cyclic voltammetry. The formation of the transparent films has been linked to the reduction of the iodine species in the film to iodide species giving rise to colorless films. Furthermore, Raman studies have revealed the presence of different iodide species like triodide, pentaiodide and iodine when anodic and cathodic potentials were applied to the films. Also, it was seen that the iodine was complexed with the BEDO-TTF polymer in a stoichiometry of 2.4: 3 [(BEDO-TTF) 2.4I3] at certain concentration in the doping technique. Raman studies were also conducted on single walled carbon nanotubes (SWCNTs) to study the defects introduced during the ball milling procedure and Ru doping. The Raman results reveal that both ball milling procedure and Ru doping leads to the formation of more defects and carbonaceous species in the SWCNTs. Thus, both electrochemical and Raman method were demonstrated to characterize the composition and properties of various materials including conducting polymer and carbon nanotubes
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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.
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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.
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Reymond-Laruinaz, Sébastien. "Biomolécules et systèmes nanostructurés : caractérisation par spectrométrie Raman exaltée de surface (SERS)." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS023/document.
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Le développement des nano et biotechnologies pousse à la recherche de techniques de caractérisation adaptées à l’étude des systèmes nanostructurés. La spectrométrie Raman exaltée de surface (SERS) est une technique d’analyse en plein essor dans ce domaine.Dans ce travail de thèse nous nous sommes attachés à étudier, par cette technique, différents types de systèmes nanostructurés : des biomolécules et des films minces inorganiques. Le but était d’accéder à des informations sur la structure et les liaisons chimiques présentes dans ces systèmes. L’étude a été complétée par des observations par microscopie électronique en transmission notamment.Dans un premier temps, a été réalisée l’étude de molécules d’intérêt biologique. L’objectif était la compréhension des modes d’interaction nanoparticules métalliques/protéines menée sur des nanoparticules d’argent bio-conjuguées avec des protéines depuis leur synthèse jusqu’à leur caractérisation. Les résultats ont montré la chimisorption des protéines à la surface de nanoparticules d'argent possiblement par leurs terminaisons azotées. La technique SERS a également été expérimentée dans le domaine des basses fréquences pour caractériser la structure de dépôts minces de caféine, molécule d’intérêt pharmaceutique.Dans un second temps, l’étude de couches minces nanostructurées par spectrométrie Raman et SERS a été réalisée. Des couches minces nanocomposites TiO2:Au, ont été étudiées pour décrire les premières étapes de croissance des nanoparticules sous l’effet de la température dans ces matériaux. Des films ultraminces de TiO2 d’épaisseur contrôlée ont été déposés sur substrats fonctionnalisés avec des nanoparticules d’or pour étudier leur exaltation par effet SERSThis work addressed the study of several kinds of nanostructured systems, biomolecules and inorganic thin films, mainly by Surface Enhanced Raman Spectroscopy (SERS). The aim was to investigate the structure and the chemical bonds. Transmission electron microscopy (TEM) was also used to complete the structural characterization of the different samples.Firstly, the study was conducted on molecules of biological interest. The aim was to study the interaction between silver nanoparticles and proteins. With this aim, silver nanoparticles bioconjugated with different proteins (hemoglobin, cytochrome C, BSA and lysozim) were synthesized. SERS results allowed concluding that proteins are chemisorbed on the silver nanoparticules surface. SERS was also used in the low frequency range to characterize the structure of thin deposits of caffeine, a molecule of pharmaceutical interest.Raman spectroscopy and SERS were also used to study nanostructured TiO2:Au thin films. The first stages of the growth of gold nanoparticles in Au doped TiO2 thin films under annealing treatments were studied by low frequency Raman spectroscopy and TEM. Finally, it was shown that SERS effect can be used for the characterization of ultra-thin TiO2 films. With this aim, ultra-thin TiO2 films were deposited by Atomic Layer Deposition on Si substrates functionalized with gold nanoparticles and studied by SERS
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Beffara, Flavien. "SERS biosensors based on special optical fibers for clinical diagnosis." Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0009.
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Malgré d'importantes percées dans le domaine de la biodétection, nous avons toujours besoin de nouveaux capteurs qui faciliteraient la détection précoce de maladies graves comme le cancer. La biopsie tissulaire classique reste la référence dans de nombreux cas. Bien que cette approche ait montré son potentiel, elle reste invasive pour les patients et les techniques de détection sont fastidieuses ou manquent de sensibilité pour détecter la maladie à un stade précoce. La spectroscopie Raman a démontré son intérêt pour la biodétection. Sa capacité à caractériser la nature chimique, la structure et l'orientation d'un analyte, en fait un candidat idéal. Les pics Raman très nets d'une molécule peuvent être considérés comme une véritable empreinte digitale. Malheureusement, le signal Raman diffusé est extrêmement faible. Cette limitation a été surmontée par la spectroscopie Raman exaltée de surface (SERS), car elle augmente considérablement le signal Raman diffusé tout en maintenant la largeur des pics du spectre d'une molécule. Malheureusement, la plupart des substrats SERS actuels sont soit des surfaces métalliques nano-rugueuses en 2D soit des nanoparticules colloïdales, qui manquent de sensibilité et de fiabilité dans les mesures avec une faible répétabilité et reproductibilité des données. Ces dernières années, des fibres optiques spéciales ont été utilisées comme plateformes SERS. Elles comportent des trous qui s'étendent sur toute leur longueur. Ces trous permettent d'incorporer l'analyte à l'intérieur de la fibre. Ainsi, une telle plate-forme représente une alternative prometteuse aux substrats plans puisque l'analyte et la lumière d'excitation peuvent interagir sur une plus grande longueur à l'intérieur des fibres. De plus, les fibres optiques sont très flexibles, compactes, et permettent un guidage de la lumière à faible perte. Par conséquent, ces capteurs à fibres présentent à la fois les capacités de détection exceptionnelles du SERS, les avantages des fibres optiques et une sensibilité et une fiabilité améliorées. Dans ce manuscrit, nous visons à créer une plateforme de biodétection qui pourrait être utilisée dans un cadre clinique. Pour cela, nous proposons d'optimiser les caractéristiques d'une topologie de fibre déjà existante. Cela nous permet d'augmenter sa sensibilité tout en améliorant sa fiabilité et sa facilité d’utilisation. Grâce à ce capteur amélioré, nous avons pu pour la première fois détecter le biomarqueur du cancer de l'ovaire dans les fluides de kystes cliniques, ce qui nous a permis de différencier le stade du cancer. Par la suite, nous proposons une nouvelle topologie de fibre, spécifiquement conçue pour augmenter encore la sensibilité des sondes à fibre basées sur le SERS. Cette amélioration est réalisée en augmentant la surface d'interaction par rapport aux sondes à fibre standard. Pour cela, le diamètre du noyau est considérablement augmenté et la quantité de lumière qui interagit avec l'analyte est contrôlée avec précision. Nous envisageons que de tels capteurs à fibres fonctionnalisés puissent être incorporés à l'intérieur d'une aiguille de biopsie afin de créer un capteur deux-en-un pour la collecte et l’analyse de fluides corporels. Les limitations associées aux aiguilles de biopsie actuelles, qui exigent une collecte et une analyse des échantillons en deux étapes, pourraient ainsi être surmontéesDespite important breakthroughs in biosensing, we are still in need of new sensors that would facilitate the early detection of severe diseases such as cancer. Classical tissue biopsy remains the gold standard in many cases. Although this approach has shown its potential, it remains invasive for the patients and the detection techniques are either tedious or lack the sensitivity to detect the disease at an early stage. Raman spectroscopy has demonstrated its interests for biosensing. Its ability to characterize the chemical nature, structure and the orientation of an analyte makes it an ideal candidate. The sharp Raman peaks of a molecule can be seen as a true fingerprint. Regrettably, Raman scattered signal is extremely weak. This limitation was overcome by surface enhanced Raman spectroscopy (SERS), since it drastically increases the Raman scattered signal while maintaining the sharp peak of the fingerprint spectrum of a molecule. Unfortunately, most of the current SERS substrates are 2D nano-roughened metal surfaces or colloidal nanoparticles, which lack the sensitivity and reliability in measurement with poor repeatability and reproducibility in the data. In the recent years, special optical fibers have been used as SERS platforms. They feature holes that run along their entire length. These holes allow for the analyte to be incorporated inside the fiber. Thus, such platform represents a promising alternative to planar substrates since the analyte and the excitation light can interact for longer length inside the fibers. In addition, optical fibers are very flexible, compact and allow for low-loss light guiding. Therefore, such fiber sensors exhibit the outstanding detection abilities of SERS, the advantages of optical fibers and improved sensitivity and reliability. In this manuscript, we aim to create a biosensing platform that could be routinely used in a clinical setting. For that, we propose to optimize the features of an already reported fiber topology. This allows us to increase its sensitivity while simultaneously improving its reliability and practicability. With this improved sensor, for the first time, we could detect the biomarker for ovarian cancer in clinical cyst fluids, which allowed us to differentiate the stage of the cancer. Subsequently, we propose a novel fiber topology, specifically designed to further increase the sensitivity of SERS-based fiber probes. This is achieved by increasing the surface of interaction compared to standard fiber sensors. For that, the core diameter is significantly increased and the amount of light that interacts with the analyte is precisely controlled. We envision that such functionalized fiber sensors could be incorporated inside a biopsy needle to create a two-in-one sensor for body fluid collection and readout that can eventually overcome the limitations associated with existing biopsy needle platforms, which demands for two-step sample collection and readout
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Costa, Jean Claudio Santos. "Desenvolvimento de sensores nanoestruturados para análises químicas por meio de técnicas espectroscópicas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-02052013-090958/.
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O uso de técnicas espectroscópicas para o estudo de questões ambientais é uma área de pesquisa que vem experimentando importante desenvolvimento em tempos recentes, e muitas linhas de investigação vêm sendo abertas. As características de sensibilidade e seletividade da técnica Raman intensificada pela superfície (SERS - Surface-enhanced Raman scattering) sugerem que ela pode ser muito útil para o estudo de amostras complexas, como as relacionadas à investigação de poluentes no ambiente. O enfoque dessa tese está voltado para o desenvolvimento de metodologias para a utilização do efeito SERS no estudo espectroscópico de diferentes classes de espécies químicas de interesse ambiental. É proposta a construção de substratos SERS de alto desempenho para uso como sensores analíticos na identificação, quantificação e estudo de aspectos relacionados à reatividade de hidrocarbonetos policíclicos aromáticos (HPA), compostos organofosforados, compostos triazínicos e compostos organoclorados. Dentre os substratos investigados, podemos mencionar nanopartículas de ouro e prata (nanobastões, nanocubos, nanofios e partículas bimetálicas) e nanopartículas de ouro e prata imobilizadas em filmes poliméricos. Buscamos estabelecer correlações entre morfologia e composição química das nanoestruturas e os mecanismos de adsorção das moléculas investigadas sobre os substratos metálicos. Utilizamos cálculos DFT (Density Functional Theory) para simular as interações adsorbato-nanopartícula possíveis, buscando o melhor entendimento dos processos de interação química entre as nanoestruturas metálicas e as substâncias de interesse.The use of spectroscopic techniques to the study of environmental issues is an area of research that has been experiencing major development in recent times. The sensitivity and selectivity characteristics of surface-enhanced Raman scattering (SERS) suggest that this technique can be very useful for the study of complex samples, such as those related to the investigation of pollutants in the environment. The focus of this thesis is dedicated to the development of methodologies for the use of the SERS effect to the spectroscopic study of different classes of chemical species of environmental interest. The construction of high-performance substrates for SERS is investigated aiming for their use as analytical sensors, identification, quantification and study of aspects related to the reactivity of polycyclic aromatic hydrocarbons (PAH), organophosphorus compounds, organochlorine compounds and triazinic compounds. Among the investigated substrates, we mention colloidal gold and silver nanoparticles of different shapes (nanorods, nanocubes, nanowires and bimetallic particles) and gold and silver nanoparticles immobilized on polymeric films. We seek to establish correlations between morphology and chemical composition of nanostructures and adsorption mechanisms of the investigated molecules on the metal substrates. We use DFT calculations (Density Functional Theory) to simulate possible adsorbate-nanoparticle interactions, allowing a better understanding of the processes of chemical interaction between the metal nanostructures and the substances of interest.
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Gorunmez, Zohre. "Finite-Difference Time-Domain (FDTD) Modeling of Nanoscale Plasmonic Substrates for Surface-Enhanced Raman Spectroscopy (SERS)." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563296001850111.
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CARA, ELEONORA. "Tailored fabrication of nanostructured substrates for surface-enhanced Raman spectroscopy applications." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2735516.
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Hong, Seongmin. "Optimization, Modification and Application of Gold Nanoparticles as the Substrates of Surface Enhanced Raman Spectroscopy." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4819.
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Lahr, Rebecca Halvorson. "Advanced Applications of Raman Spectroscopy for Environmental Analyses." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/54010.
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Due to an ever-increasing global population and limited resource availability, there is a constant need for detection of both natural and anthropogenic hazards in water, air, food, and material goods. Traditionally a different instrument would be used to detect each class of contaminant, often after a concentration or separation protocol to extract the analyte from its matrix. Raman spectroscopy is unique in its ability to detect organic or inorganic, airborne or waterborne, and embedded or adsorbed analytes within environmental systems. This ability comes from the inherent abilities of the Raman spectrometer combined with concentration, separation, and signal enhancement provided by drop coating deposition Raman (DCDR) and surface-enhanced Raman spectroscopy (SERS).
Herein the capacity of DCDR to differentiate between cyanotoxin variants in aqueous solutions was demonstrated using principal component analysis (PCA) to statistically demonstrate spectral differentiation. A set of rules was outlined based on Raman peak ratios to allow an inexperienced user to determine the toxin variant identity from its Raman spectrum. DCDR was also employed for microcystin-LR (MC-LR) detection in environmental waters at environmentally relevant concentrations, after pre-concentration with solid-phase extraction (SPE). In a cellulose matrix, SERS and normal Raman spectral imaging revealed nanoparticle transport and deposition patterns, illustrating that nanoparticle surface coating dictated the observed transport properties. Both SERS spectral imaging and insight into analyte transport in wax-printed paper microfluidic channels will ultimately be useful for microfluidic paper-based analytical device (𝜇PAD) development. Within algal cells, SERS produced 3D cellular images in the presence of intracellularly biosynthesized gold nanoparticles (AuNP), documenting in detail the molecular vibrations of biomolecules at the AuNP surfaces. Molecules involved in nanoparticle biosynthesis were identified at AuNP surfaces within algal cells, thus aiding in mechanism elucidation.
The capabilities of Raman spectroscopy are endless, especially in light of SERS tag design, coordinating detection of analytes that do not inherently produce strong Raman vibrations. The increase in portable Raman spectrometer availability will only facilitate cheaper, more frequent application of Raman spectrometry both in the field and the lab. The tremendous detection power of the Raman spectrometer cannot be ignored.Ph. D.
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Weber, Verena. "Plasmonic nanostructures for the realization of sensor based on surface enhanced Raman spectroscopy." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423838.
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The field of Plasmonics deals with interaction processes between an electromagnetic radiation of appropriate wavelength and the conduction electrons of a metal. The induced collective oscillation of the electrons is called Plasmon Resonance. The Localized Surface Plasmon Resonance (LSPR) occur when the excitation involves surface electrons of nanostructures with dimensions less or comparable to the excitation wavelength. The excitation causes a strong enhancement of the local field around the metal nanostructure, which, combined with Raman Spectroscopy, could be very interesting for molecular sensing. The Raman technique is well known for providing a fingerprint spectrum of a given molecule, but has the great limitation of low sensibility. By adsorbing the analyte of interest on a plasmonic substrate in the region of enhanced local field, high detection sensitivity can be reached through Surface Enhanced Raman Spectroscopy (SERS).
The first part of the present work is focused on the synthesis and characterization of gold and silver nanoparticles (Au and Ag NPs) and gold nanoshells (Au NSs) and their exploitation for the realization of SERS substrates, both in colloidal solutions and on solid supports. Different metal nanostructures give the possibility to exploit the LSPR in a wide spectral range, from the Vis to the near IR. Their optical and morphological characterization is carried out with conventional techniques, like TEM, AFM, UV-Vis absorption and Surface Enhanced Raman Spectroscopy, and with a new characterization technique, rarely used in this research field: the Photoacoustic Spectroscopy. It provides information about the absorption contribution to the total extinction of a plasmonic nanostructure. From a rigorous measurement of the SERS enhancement factor and from Photoacoustic Spectroscopy data at different excitation wavelengths, some considerations could be done concerning the relation of far field extinction and near field SERS properties. SERS EF profile measurements on liquid and solid SERS substrates demonstrated the presence of hot spots. The solid SERS substrates were chemically stable, homogeneous and reproducible and showed EF values of about 104-105. In colloidal solution, the EF values were about 103-106, depending on the metal nanostructure. Photoacoustic measurements performed on Au NSs in solution were in agreement with theoretical predictions found in literature.
In the second part of the work, the plasmonic substrates, realized with Au NPs and Au NSs, were used for the realization of label free SERS sensors, to detect toxic aromatic chemical species and biological molecules. A sensor for toxic volatile compounds, based on Au NPs and Au NSs substrates coupled with a porous organic-inorganic hybrid sol-gel matrix, was realized. The matrix was specifically chosen for exhibiting a high-affinity interaction to aromatic hydrocarbons. The enhancement activity of the Au NPs and Au NSs substrates on the sol gel matrix alone was demonstrated. Some problems in the xylene detection process through SERS were probably due to the fast matrix regeneration under the laser radiation. Although, the enhanced SERS efficiency due to the detection design was demonstrated.
Another application was based on the development of a novel label-receptor system, based on the cromophore 4-hydroxyazobenzene-2 carboxylic acid (HABA) and its specific antibody, to be used in bio-analytical applications. The interesting behaviour of the HABA dye relies in changing its tautomeric structure from an azo to a hydrazo form, thanks to the interaction with its antibody. This structural change can be exploited for SERS detection of the label-receptor interaction. Properly synthesized and characterized HABA derivatives were adsorbed onto SERS substrates, further incubated in the antibody solution. The HABA signals were well visible on both Au NSs and Au NPs substrates. No HABA change could be detected through SERS, because the antibodies extracted in vivo from two rabbits, do not cause the quantitative change of the HABA structure.La Plasmonica si occupa dell’interazione di una radiazione elettromagnetica di opportuna lunghezza d’onda con gli elettroni di conduzione di un metallo. L’oscillazione collettiva degli elettroni, indotta da questa interazione, è chiamata appunto Risonanza Plasmonica. La risonanza plasmonica di superficie localizzata avviene quando gli elettroni coinvolti sono quelli di superficie di un metallo nanostrutturato con dimensioni minori o comparabili alla lunghezza d’onda di eccitazione. Da questa eccitazione deriva una forte amplificazione del campo elettromagnetico locale, localizzato nelle immediate vicinanze della nanostruttura metallica. Tale amplificazione, unita a una tecnica di rivelazione spettroscopica specifica, quale la spettroscopia Raman, può essere sfruttata per la realizzazione di sensori molecolari. La tecnica Raman è conosciuta come altamente specifica, perché in grado di fornire uno spettro caratteristico della singola molecola, identificandone univocamente la presenza e la costituzione. La sua maggiore limitazione, però, è la bassa sensibilità. Ponendo l’analita in prossimità di un substrato plasmonico, proprio nella regione di forte amplificazione del campo locale, la sensibilità di rivelazione viene fortemente aumentata, dando origine alla spettroscopia Raman amplificata da superfici (SERS). La prima parte del presente lavoro è focalizzata sulla sintesi e sulla caratterizzazione di nanoparticelle d’argento, d’oro e di nano gusci d’oro (chiamati nanoshell) e sul loro impiego per la realizzazione di substrati SERS, sia in soluzione colloidale che su substrato solido. L’utilizzo di differenti nanostrutture metalliche, dà la possibilità di sfruttare la risonanza plasmonica localizzata di superficie in un’ampia regione spettrale, che si estende dal visibile al vicino infrarosso. La caratterizzazione ottica e morfologica delle nanostrutture è stata effettuata con tecniche convenzionali, come la spettroscopia di assorbimento UV-visibile, il SERS, la microscopia elettronica a trasmissione e la microscopia a forza atomica. Ad esse è stata affiancata anche una tecnica raramente usata nell’ambito della plasmonica: la spettroscopia fotoacustica. Questa può fornire informazioni riguardanti il contributo di assorbimento, all’estinzione totale, di una nanostruttura plasmonica. Da una rigorosa misura dei fattori di amplificazione e delle proprietà di fotoacustica al variare della lunghezza d’onda, possono essere fatte alcune considerazioni riguardanti la possibile relazione tra l’estinzione (proprietà di campo lontano) e l’ amplificazione SERS (proprietà di campo vicino). Le misure dei profili di eccitazione SERS su substrati plasmonici in liquido e su supporto solido, hanno evidenziato la presenza di hot spots, ovvero di zone fortemente amplificate dall’interazione di due o più nanostrutture. I substrati SERS solidi sono risultati chimicamente stabili, omogenei e riproducibili; essi presentano valori di fattori di amplificazione attorno a 104-105. In soluzione colloidale, i fattori di amplificazione delle nanostrutture hanno raggiunto valori nell’intervallo 103-106, dipendentemente dal tipo di nanostruttura metallica investigata. Le misure di fotoacustica effettuate su soluzioni colloidali di nanoshell d’oro si sono rivelate in accordo con le predizioni teoriche di letteratura. Nella seconda parte del lavoro, i substrati plasmonici, realizzati principalmente con nanoparticelle e nanoshell d’oro, sono stati impiegati per la realizzazione di sensori SERS per la rivelazione di specie chimiche e biologiche. É stato realizzato un sensore di composti tossici aromatici volatili, accoppiando un substrato plasmonico con un film poroso di sol gel ibrido organico-inorganico. La componente organica della matrice sol gel è stata appositamente scelta per la sua alta affinità a composti aromatici, quali lo Xilene. È stata dimostrata l’amplificazione dei segnali della matrice da parte della componente plasmonica, ma si sono riscontrati alcuni problemi nella rivelazione delle molecole di analita attraverso il SERS. La difficoltà nella rivelazione è probabilmente dovuta al veloce deadsorbimento dello Xilene dalla matrice a causa del forte riscaldamento locale causato dalla radiazione laser. Nonostante questo, si è comunque dimostrata l’aumentata efficienza del sensore progettato, rispetto ai suoi componenti singoli. La seconda applicazione studiata ha riguardato la realizzazione di un sistema analita-accettore innovativo, che può essere utilizzato per diverse applicazioni bioanalitiche; esso è basato sull’interazione tra un cromoforo diazobenzenico (HABA) e il suo anticorpo specifico. Alla base dell’applicazione si trova una proprietà interessante del suddetto cromoforo, che è quella di cambiare la sua struttura molecolare, passando da una forma azo alla forma idrazo, dopo aver interagito con il suo anticorpo specifico. Questa variazione nella struttura molecolare può essere sfruttata per la rivelazione dell’avvenuta interazione analita-accettore, mediante SERS. Alcuni derivati di questo cromoforo sono stati sintetizzati e caratterizzati in modo da poter essere adsorbiti su un substrato SERS, che viene successivamente incubato in una soluzione di anticorpo. I segnali SERS della molecola di HABA sono risultati ben visibili sia sui substrati di nanoparticelle che di nanoshell d’oro. Purtroppo non è stato possibile rivelare la variazione strutturale del cromoforo, in quanto gli anticorpi, estratti in vivo da due coniglietti, inducono solo un parziale cambio di struttura, rendendo la rivelazione SERS alquanto difficile.
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Levene, Clare. "Advanced Raman, SERS, and ROA studies of biomedical and pharmaceutical compounds in solution." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/advanced-raman-sers-and-roa-studies-of-biomedical-and-pharmaceutical-compounds-in-solution(1c05f618-b1c2-4663-870a-3d51b32dad7b).html.
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The primary purpose of this study was to investigate the combination of experimental and computational methods in the search for reproducible colloidal surface-enhanced Raman scattering of pharmaceutical compounds. In the search for optimal experimental conditions for colloidal surface-enhance Raman scattering, the amphipathic β-blocker propranolol was used as the target molecule. Fractional factorial designs of experiments were performed and a multiobjective evolutionary algorithm was used to find acceptable solutions, from the results, that were Pareto ranked. The multiobjective evolutionary algorithm suggested solutions outside of the fractional factorial design and the experiments were then performed in the laboratory. The results observed from the suggested solutions agreed with the solutions that were found on the Pareto front. One of the experimental conditions observed on the Pareto front was then used to determine the practical limit of detection of propranolol. The experimental conditions that were chosen for the limit of detection took into account reproducibility and enhancement, the two most important parameters for analytical detection using surface-enhanced Raman scattering. The principal conclusion to this study was that the combination of computational and experimental methods can reduce the need for experiments by > 96% and then selecting solutions from the Pareto front improved limit of detection by a factor of 24.5 when it was compared to the previously reported limit of detection for propranolol. Using the same experimental conditions that were used for the limit of detection, these experiments were extended to plasma spiked with propranolol in order to test detection of this pharmaceutical in biofluids. Concentrations of propranolol were prepared using plasma as the solvent and measured for detection using colloidal surface-enhanced Raman scattering. Detection was determined as <130 ng/mL, within physiological concentrations, previously achieved using separation techniques. The second part of this thesis also involved a combination of experimental and computational methods. Raman optical activity was utilized to investigate secondary structure of amino acids and diamino acid peptides in combination with density functional theory calculations. Amino acids are important biological molecules that have vital functions in the biological system. They have been recognized as neurotransmitters and implicated in neurodegenerative diseases. Raman and Raman optical activity experimental results were compared to determine site-specific acetylation, marker bands for constitutional isomers and identification of functional groups that interact with the solvent. The experimental spectra were then compared to those from the density functional theory calculations. The results indicated that; constitutional isomers cannot be distinguished from the Raman spectra but can be distinguished from the Raman optical activity spectra, site-specific acetylation can be identified from the Raman spectra, however, Raman optical activity provides more structural information in relation to acetylation. When the results were compared to the density functional theory calculations for the diamino acid peptides the results agreed reasonably well, however, agreement was not as good for the monoamino acids because diamino acid peptides support fewer conformations due to the peptide bond whereas monoamino acids can adopt a far greater number of conformations. Combined computational and experimental techniques have developed the ability to detect and characterize biomedical compounds, a significant move in the advancement of Raman spectroscopies.
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Hughes, Juanita Maree. "A novel identification method for ultra trace detection of biomolecules using functionalised Surface Enhanced Raman Spectroscopy (SERS)." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/72864/2/Juanita_Hughes_Thesis.pdf.
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This thesis developed a new method for measuring extremely low amounts of organic and biological molecules, using Surface enhanced Raman Spectroscopy. This method has many potential applications, e.g. medical diagnosis, public health, food provenance, antidoping, forensics and homeland security. The method development used caffeine as the small molecule example, and erythropoietin (EPO) as the large molecule. This method is much more sensitive and specific than currently used methods; rapid, simple and cost effective. The method can be used to detect target molecules in beverages and biological fluids without the usual preparation steps.
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Zeng, Jianbo. "Gold Nanoshells: Synthesis and Applications to In Situ SERS." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1362843561.
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Cordeiro, Denise de Sales. "Estudo do comportamento químico de desreguladores endócrinos utilizando o efeito SERS e processos fotoquímicos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-04092012-102703/.
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Uma questão ambiental preocupante é a contaminação do meio ambiente por substâncias que interagem com os sistemas endócrinos de seres humanos e animais. Tais substâncias são denominadas desreguladores endócrinos e, como outros poluentes ambientais, apresentam uma variedade de fontes e grande potencial agressor à saúde humana. Neste trabalho, buscamos a aplicação de técnicas de espectroscopia vibracional e técnicas eletroquímicas ao estudo de desreguladores endócrinos, em termos de sua detecção, caracterização, estudo de sua reatividade, desenvolvimento de métodos para sua degradação fotoquímica, estudo dos mecanismos envolvidos e características dos produtos de degradação. O enfoque é voltado ao uso de técnicas espectroscópicas, com especial destaque para o desenvolvimento de metodologias de espectroscopia vibracional intensificadas, associadas ou não a sistemas eletroquímicos. Dentre os compostos considerados desreguladores endócrinos, o nosso trabalho é dedicado ao estudo fotoquímico e espectroeletroquímico das seguintes substâncias: o difenilalcano bisfenol A (BPA), os herbicidas triazínicos ametrina e atrazina, e os compostos organoclorados ácido 2,4-diclorofenoxiacético (2,4-D) e 2,4-diclorofenol (2,4-DCF). O estudo de processos de fotólise e degradação fotocatalítica mediada por TiO2 foram realizados para o BPA e para a ametrina. Tais processos mostram-se importantes para a remoção destes compostos do meio ambiente. Os estudos fotocatalíticos foram estendidos ainda para o uso de compósitos TiO2-Pr como catalisadores. Foi observado que a dopagem do TiO2 pelo íon terra rara praseodímio resulta em alterações nas propriedades físico-químicas do material semicondutor, sendo um método valioso para o aumento da atividade fotocatalítica do TiO2. Conclui-se ainda pela necessidade do controle da porcentagem de modificação química para a otimização do processo fotocatalítico, sendo a proporção de 1% praseodímio considerada ótima. O estudo de processos de fotólise e degradação fotocatalítica do BPA mediado por TiO2 mostra diferenças significativas entre o processo de degradação e mineralização, relacionadas à formação de intermediários orgânicos recalcitrantes. Para a ametrina observa-se que a fotólise e a fotocatálise envolvem mecanismos de degradação distintos. Estudos espectroeletroquímicos dos desreguladores endócrinos (DEC) foram conduzidos através de espectroscopia Raman intensificada (efeito SERS) visando a compreensão da natureza da interação química entre os adsorbatos e superfícies metálicas nanoestruturadas, bem como a caracterização vibracional dos produtos de processos faradáicos desses compostos sobre eletrodos. Produtos de reações químicas de oxidação e redução dos DEC foram identificados através de modificações espectrais em função de potenciais eletroquímicos anódicos e catódicos.An environmental issue of concern is contamination of the environment by substances which interact with the endocrine systems of humans and animals. Such substances are called endocrine disruptors (ED) and, like other environmental pollutants, may produce adverse effects in human health. In this work, we explore the application of vibrational spectroscopy and electrochemical techniques in the study of ED, in terms of their detection, characterization, study of their reactivity, development of methods for their photochemical degradation, study of the involved mechanisms and characteristic of degradation products. The approach employs the use of advanced spectroscopic techniques, with special attention for the development of methodology of surface-enhanced vibrational spectroscopy, associated or not with electrochemical systems. Among the compounds thought to cause endocrine disruption, the present study is dedicated to the photochemical and electrochemical study of the following substances: the plasticizer bisphenol A (BPA), the triazinic pesticides ametrine and atrazine, and the organochlorine compounds 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenol. The study of photolytic and TiO2-mediated photocatalytic degradation was carried out for BPA and ametrine. Such processes are important for the removal of such substances from the environment. The photocatalytic studies were extended to include the use of TiO2-Pr composite as catalysts. The doping of TiO2 by the rare earth ion praseodymium results in changes in the physicochemical properties of semiconducting material, being a valuable method for enhancing the photocatalytic activity of TiO2. Our results showed the need of percentage control of the chemical modification for the optimization of the photocatalytic process, with the 1% praseodymium/titanium ration the optimal composition. The study of photolysis and TiO2-mediated photocatalytic degradation processes of BPA shows significant differences between the degradation and mineralization, suggesting the production of recalcitrant organic compounds. For ametrine, photolysis and photocatalytic degradation processes were found to occur via different mechanisms. Spectroelectrochemical studies of endocrine disruptors (ED) were carried out through surface-enhanced Raman spectroscopy (SERS effect) aiming at the understanding of the nature of the chemical interaction between these molecules and nanostructured metallic surfaces, and at the vibrational characterization of the products formed by faradaic charge transfer processes. Products of oxidation and reduction chemical reactions were identified through spectral changes observed in the SERS spectra as a function of cathodic and anodic potentials.
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Israelsen, Nathan. "Surface-Enhanced Raman Spectroscopy-Based Biomarker Detection for B-Cell Malignancies." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4605.
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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.
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Doctor, Erika L. "Development of a Surface-Enhanced Raman Spectroscopy Method for the Detection of Benzodiazepines in Urine." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1642.
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Benzodiazepines are among the most prescribed compounds for anti-anxiety and are present in many toxicological screens. These drugs are also prominent in the commission of drug facilitated sexual assaults due their effects on the central nervous system. Due to their potency, a low dose of these compounds is often administered to victims; therefore, the target detection limit for these compounds in biological samples is 10 ng/mL. Currently these compounds are predominantly analyzed using immunoassay techniques; however more specific screening methods are needed.
The goal of this dissertation was to develop a rapid, specific screening technique for benzodiazepines in urine samples utilizing surface-enhanced Raman spectroscopy (SERS), which has previously been shown be capable of to detect trace quantities of pharmaceutical compounds in aqueous solutions. Surface enhanced Raman spectroscopy has the advantage of overcoming the low sensitivity and fluorescence effects seen with conventional Raman spectroscopy. The spectra are obtained by applying an analyte onto a SERS-active metal substrate such as colloidal metal particles. SERS signals can be further increased with the addition of aggregate solutions. These agents cause the nanoparticles to amass and form hot-spots which increase the signal intensity.
In this work, the colloidal particles are spherical gold nanoparticles in aqueous solution with an average size of approximately 30 nm. The optimum aggregating agent for the detection of benzodiazepines was determined to be 16.7 mM MgCl2, providing the highest signal intensities at the lowest drug concentrations with limits of detection between 0.5 and 127 ng/mL. A supported liquid extraction technique was utilized as a rapid clean extraction for benzodiazepines from urine at a pH of 5.0, allowing for clean extraction with limits of detection between 6 and 640 ng/mL. It was shown that at this pH other drugs that are prevalent in urine samples can be removed providing the selective detection of the benzodiazepine of interest.
This technique has been shown to provide rapid (less than twenty minutes), sensitive, and specific detection of benzodiazepines at low concentrations in urine. It provides the forensic community with a sensitive and specific screening technique for the detection of benzodiazepines in drug facilitated assault cases.
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Corio, Paola. "A contribuição do mecanismo de transferência de carga para o efeito SERS em interfaces eletroquímicas." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-03072009-114359/.
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Neste trabalho estudamos o efeito SERS de moléculas adsorvidas em sistemas eletroquímicos em termos da participação do mecanismo de transferência de carga na intensificação total observada. Desenvolvemos um modelo para o mecanismo químico de transferência de carga assitido por fótons, de maneira a explicar a variação do potencial de máxima intensificação SERS (Vmax) com a energia da radiação excitante. O modelo permite também o uso da expressão para o espalhamento Raman no domínio do tempo para o cálculo de perfis de excitação SERS (intensidade SERS versus potencial aplicado) de moléculas adsorvidas em interfaces eletroquímicas. Este método de cálculo dos perfis de excitação SERS foi aplicado para os casos da piridina e do íon complexo [Fe2(CN)104,4\'-bpy]6- em eletrodo de prata. Os resultados mostram existir uma boa relação entre os perfis calculados e os obtidos experimentalmente. Como resultado dos cálculos efetuados, o modelo fornece ainda dados sobre o deslocamento das curvas de poço potencial dos estados excitados envolvidos nos processos de transferência de carga assistidos por fótons. Nos capítulos seguintes, estudamos algumas conseqüências deste modelo, e sua aplicação em diferentes sistemas químicos. Um dos sistemas estudados foi o íon complexo [Ru(bpy)2viol]+ adsorvido em eletrodo de prata. Observa-se que a intensidade relativa dos modos vibracionais de cada um dos ligantes varia com o potencial aplicado ao eletrodo. Esses resultados podem ser explicados considerando-se dois processos de transferência de carga superficie → adsorbato assistidos por fótons. O primeiro deles deve-se a uma transição envolvendo estados doadores próximos ao nível de Fermi do metal (EF) e estados receptores (orbitais π*) localizados no violurato. O segundo envolve estados doadores em EF e orbitais π* da bpy. A energia da transição de transferência de carga metal → adsorbato varia com o potencial aplicado. Existe portanto a possibilidade de se alcançar diferentes estados eletrônicos excitados do adsorbato, intensificando, seletivamente, diferentes cromóforos com um único comprimento de onda. Assim, através da variação do potencial aplicado ao eletrodo é possível modular a transição de transferência de carga Ag → complexo de modo a envolver cada um dos diferentes ligantes. Estudamos também o mecanismo envolvido no efeito SERS da molécula FePc (ftalocianina de ferro) em eletrodo de prata. Nesse sistema, foi possível apresentar uma versão mais detalhada para o efeito químico envolvido na intensificação SERS incluindo o efeito de múltiplos estados excitados e acoplamento vibrônico, enfatizando as relações de simetria e overlap de funções de onda que regem os mecanismos de intensificação Raman ressonante. A excitação dos espectros SERS em comprimentos de onda fora da condição de Raman ressonante pode intensificar modos vibracionais de simetria a2g (não permitidos no espectro Raman normal) desde que o potencial aplicado esteja próximo à condição de ressonância para uma transição de transferência de carga superficie/adsorbato. O mecanismo químico de intensificação envolvido no efeito SERS desse sistema pode ser descrito como um processo de transferência de carga modulado pelo potencial, envolvendo dois estados doadores da FePc e um estado aceptor localizado na superficie do eletrodo de prata. Enquanto os modos totalmente simétricos (a1g) são intensificados por um mecanismo de Franck-Condon, os modos a2g têm a simetria apropriada para acoplar dois estados eletrônicos de simetria A1u e A2u, sendo intensificados através do mecanismo de Herzberg- Teller. Os efeitos da natureza química do solvente, e das interações solvente-soluto nas geometrias de adsorção e nas posições dos estados eletrônicos do adsorbato, são analisados para os ciano complexos Fe(phen)2(CN)2 e [Fe2(BPE)(CN)10]6-. Os resultados obtidos demonstram a influência decisiva da natureza química de solventes e eletrólitos suporte na espectroscopia de espécies adsorvidas em interfaces eletroquímicas. De fato, a natureza das interações solvente-adsorbato ou eletrólito-adsorbato podem determinar a ligação à superficie, e, desta maneira, intensificação seletiva de modos vibracionais da molécula pode ser obtida. A partir do estudo do processo de transferência de carga entre a superficie e os complexos adsorvidos através dos perfis de excitação SERS foi possível, em alguns casos, mapear os níveis de energia do adsorbato com relação ao nível de Fermi do metal.In this work, attention has been given to systems in which the charge transfer (CT) mechanism is contributing to the enhancement of the Raman scattering of species adsorbed on metal surfaces in order to address the participation of a resonance Raman effect on this part of the total enhancement. A model for the adsorbate-metal surface interaction and the charge transfer mechanism for surface-enhanced Raman scattering (SERS) is presented. The fundamental observation behind the currently proposed model is that ali previous theories indicate that Raman intensity should be at maximum when the incident laser frequency is resonant with a surface/adsorbate charge transfer band. This fact leads to the conclusion that this aspect of the chemical effect may be due to a resonance Raman mechanism. Therefore, for such mechanism to be valid, the chemical effect of SERS must follow the already well established principies of resonance Raman theory. In this model, the metal surface provides a source of electrons that may, upon interaction with light, flow into and out of the adsorbed species. Based on this model we have proposed a formalism derived from the time-domain description of the resonance Raman effect that describes the dependence of the SERS intensities of molecules adsorbed in electrochemical interfaces upon the applied potential. This approach accounts for the enhancement of totally symmetric modes via a Franck-Condon mechanism, and only one electronic excited state of the adsorbate/surface system is considered. The analytical expression derived to calculate the SERS intensity versus applied potential profiles and their dependence on the exciting radiation has been applied for pyridine and for the ion complex [Fe2(CN)10bpy]6- adsorbed on a silver electrode. A good agreement between calculated and experimental excitation profiles have been obtained for both investigated species. Resonance Raman spectroscopy is also an electronic spectroscopy, and, as presented in this work, the SERS effect, or part of it, is also an electronic spectroscopy. Its intensity contains, therefore, information about the structure of the excited electronic state involved in the charge transfer process. This information is provided by the calculation of the SERS excitation profiles according to the derived expression in the form of ΔK values. The remaining sections of this work are dedicated to the study of the SERS effect of coordination compounds adsorbed on silver electrodes. One of the investigated systems is the mixed ligand ion complex [Ru(bpy)2viol]+. The SERS measurements have shown that the vibrational modes of both ligands can be selectively enhanced by changing the electrochemical applied potential at a fixed laser excitation energy. This result indicates the presence of two different metal to adsorbate photon assisted charge transfer processes. The first one involves a density of donor states near the Fermi level (EF) of the metal and na acceptor state localized on the violurate ligand, while the second process involves na acceptor state localized on the bpy ligand. These results demonstrate the possibility of reaching different excited electronic states of molecules adsorbed on electrode surfaces, selectively enhancing different chromofores by changing the applied potential and of assigning electronic charge transfer transitions based on SERS results. In order to provide a more detailed description of the charge transfer mechanism of enhancement working in the SERS effect of adsorbed molecules, including the role of multiple excited electronic states, vibronic coupling and symmetry selection rules, the SERS effect of iron phthalocyanine is discussed. The charge transfer mechanism of enhancement in this system is characterized as a potential modulated charge transfer process involving two donor states at the FePc and an acceptor state at the silver electrode surface. Excitation of the SERS spectra at wavelengths off resonance with the Q-band may enhance the a2g vibrational modes (non allowed modes at normal Raman condition), via a Herzberg-Teller mechanism, providing that the applied potential is dose to the resonance condition for the adsorbate to metal charge transfer transition. The effects of the chemical nature of the solvent in the adsorption geometry and in the position of the electronic states of adsorbates is discussed for the cyano complexes Fe(phen)2(CN)2 and [Fe2(BPE)(CN)10]6-. The results obtained have demonstrated the decisive role played by the chemical nature of solvents and supporting electrolytes in the surface-enhanced spectroscopy of species adsorbed at electrochemical interfaces. In fact, the nature of solvent or electrolyte - molecule interaction can determine the bonding to the surface, and therefore, selective enhancement of vibrational modes within a molecule can be accomplished. Based on the charge transfer processes between the surface and the adsorbed molecules probed by the SERS excitation profiles, it has been possible, in some cases, to determine the position of the energy levels of the adsorbate in relation to the Fermi level of the metal electrode.
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Kwon, Yong-Hyok [Verfasser], and Heinz-Detlef [Akademischer Betreuer] Kronfeldt. "Surface-Enhanced Raman Scattering (SERS) Surfaces for in-situ trace analysis of PAHs in water by Shifted Excitation Raman Difference Spectroscopy (SERDS) / Yong-Hyok Kwon. Betreuer: Heinz-Detlef Kronfeldt." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1021976393/34.
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Marsich, Lucia. "Design and synthesis of functionalized metal nanoparticles for bio-analysis with surface-enhanced Raman scattering (SERS)." Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8580.
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2011/2012The objective of this doctoral research is the development and the implementation of SERS-active substrates with biological samples. The substrates consist in coated silver nanoparticles synthesized by chemical reduction of a silver salt. The biological samples are the anionic chromophore bilirubin and two heme protein, the cationic cytochrome-c and the anionic protein cytochrome b5. In the first part of this work, positively charged nanoparticles were prepared by coating citrate-reduced silver nanoparticles with the cationic polymer poly-L-lysine and were employed with bilirubin in the experiments listed below: detection of nanomolar bilirubin concentrations in aqueous solutions, showing that the SERS intensity increases linearly with concentration in a range from 10 nM to 200 nM, allowing quantitative analysis of bilirubin aqueous solutions. indirect quantification of bilirubin cellular up-take, demonstrating the ability to detect the bilirubin also in a buffer solution suitable for cell growth with pH 7.4. Since the bilirubin quantification at this pH is no longer possible, the poly-L-lysine was substituted by two polymers with a quaternary nitrogen atom. bilirubin measurement in serum, but TEM images highlights the formation of a albumin layer around the nanoparticles, blocking the interaction between bilirubin and the nanoparticles. Hence the citrate-reduced silver nanoparticles were coated with an hydrophobic capping and re-dispersed in hexane, to avoid the albumin layer around the nanoparticles. In the second part of this doctoral thesis, silver nanoparticles were prepared via seed growth method and subsequently coated with chitosan or silica in order to obtain positively or negatively charged nanoparticles respectively. Such substrates enhance the spectrum of the cytochrome-c and cytochrome-b5 on polished silver electrode without directly interact with the protein. Thanks to the presence of chitosan or silica coated nanoparticles, the cytochrome-c and cytochrome-b5 can be detected on a gold substrate.
L’obiettivo di questo dottorato è lo sviluppo e l’implementazione di substrati SERS attivi con campioni biologici. Nanoparticelle di argento ricoperte sono state scelte come substrati. I campioni biologici analizzati sono la bilirubina e due proteine eme, il citocromo-c (cationico) e il citocromo-b5 (anionico). Nella prima parte di questo lavoro le nanoparticelle di argento sono state preparate usando come agente riducente il citrato e successivamente sono state ricoperte con un polimero cationico, la poli-lisina. Le nanoparticelle cariche positivamente così ottenute sono state impiegate con la bilirubina nei seguenti esperimenti: rilevazione di concentrazioni nano-molari di bilirubina in soluzioni acquose, dimostrando che per concentrazioni comprese tra 10 e 200 nM, l’intensità degli spettri SERS aumenta linearmente con la concentrazione. È quindi possibile l’analisi quantitativa di bilirubina in soluzioni acquose. quantificazione indiretta dell’assorbimento cellulare di bilirubina, documentando la possibilità di rilevare la bilirubina in una soluzione tampone che permetta la crescita cellulare a pH 7.4. Dal momento che la quantificazione della bilirubina in questa soluzione buffer non è più possibile, la poli-lisina è stata sostituita con due polimeri che presentano un azoto quaternario. misura della bilirubina nel siero, ma le immagini TEM evidenziano la formazione intorno alle nanoparticelle di uno strato di albumina, che impedisce l’interazione della bilirubina con le nanoparticelle ricoperte di poli-lisina. Per evitare la formazione dello strato di albumina, le nanoparticelle di argento sono state quindi ricoperte con un capping idrofobico e ridisperse in esano. Nella seconda parte di questa tesi di dottorato, le nanoparticelle di argento sono state preparate a partire da nanoparticelle di qualche nanometro e successivamente ricoperte con chitosano o silice. Lo spettro del citocromo-c e del citocromo-b5 sono stati amplificati grazie alla presenza di queste nanoparticelle senza interagire direttamente con le proteine. Grazie alla presenza delle nanoparticelle ricoperte di chitosano o silice, il citocromo-c e il citocromo-b5 sono stati misurati su un substrato d’oro.
XXV Ciclo
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Petroni, Cintia Regina. "Síntese e funcionalização de nanopartículas de ouro utilizando um modelo de substância húmica comercial." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05082013-154550/.
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Corantes orgânicos são uma importante classe de poluentes ambientais, sendo que a natureza da interação de tais espécies com ácidos húmicos determina seu comportamento e destino ambiental. Este trabalho investiga abordagens diferentes para a síntese de nanopartículas de ouro-ácido húmico (NPs Au/AH), o desempenho destas partículas como sensores para a determinação de traço de corantes orgânicos e da natureza da sua interação química com ácidos húmicos por técnicas de espectroscopia Raman intensificada por superfície (surface-enhanced Raman scattering, SERS). As nanopartículas de ouro foram obtidas de forma direta em meio aquoso. A síntese foi realizada na presença de ácido húmico em vários valores de pH e na presença e na ausência de citrato de sódio. Nesta abordagem, o ácido húmico apresenta propósitos diferentes. Na síntese das nanopartículas, ele serve como agente redutor e para a estabilização da superfície, impedindo a coalescência das nanopartículas em meio aquoso. Considerando-se a utilização de nanopartículas como substratos SERS-ativos, o ácido húmico serve como uma fase de extração associada com a plataforma SERS, favorecendo a interação dos corantes orgânicos com as nanopartículas metálicas. Esta abordagem pode ser utilizada para aumentar a sensibilidade e seletividade da técnica SERS e evitar a interferência de outras espécies em solução. É também importante mencionar que o ácido húmico dá origem a um espectro Raman muito fraco e, portanto, não interfere de forma significativa na detecção espectroscópica das espécies de interesse. As NPs Au/AH obtidas foram caracterizadas por espectroscopia eletrônica, microscopia eletrônica de varredura e SERS, a fim de estabelecer uma correlação entre a sua morfologia, plasmon superficial, e seu uso potencial como substratos SERS. As NPs Au/AH foram utilizadas como substratos SERS no estudo de corantes têxteis aniônicos e catiônicos. Os espectros Raman, nestes casos, foram atribuídos ao complexo formado pelo ácido húmico e cada uma das espécies de interesse. Os resultados obtidos revelaram uma dependência significativa entre as propriedades morfológicas e eletrônicas das NPs Au/AH com o procedimento de síntese, e também uma interação preferencial entre as nanopartículas e os corantes catiônicos. Conclui-se que as NPs Au/AH podem proporcionar uma abordagem útil para a caracterização espectroscópica de espécies relevantes para o ambiente e sua interação química com os ácidos húmicos, através do uso da espectroscopia Raman intensificada pela superfícieOrganic dyes are an important class on environmental pollutants, and the nature of the interaction of such species with humic acid strongly determines their environmental behavior and fate. This work investigates different approaches for the synthesis of humic acid-gold nanoparticles (HA-AuNP), the performance of these particles as sensors for trace determination of organic dyes and the nature of their chemical interaction with humic acids by surface-enhanced Raman scattering (SERS). The Au nanoparticles were obtained by direct fabrication in aqueous media.The synthesis were carried out in the presence of humic acid at various pH values, and in the presence and absence of sodium citrate. In this approach, humic acid serves different purposes. In the synthesis of the nanoparticles, they serve as reducing agent and for surface stabilization, preventing coalescence of the nanoparticles in aqueous media. Considering the use of the nanoparticles as SERSactive substrates, the humic acid serves as an extraction phase associated with the SERS platform, favoring the interaction of the organic dyes with the metallic nanoparticles. This approach can be used to enhance the sensitivity and selectivity of SERS technique and avoid interference from other species in solution. It is also important to mention that the humic acid gives rise to a very weak Raman spectrum, and therefore does not interfere significantly in the spectroscopic detection of the species of interest. The obtained HA-AuNPs were characterized by electronic spectroscopy, scanning electron microscopy and SERS, in order to establish a correlation between their morphology, surface plasmon, and their potential use as SERS platforms. The HA-AuNPs have been applied as SERS substrates for anionic and cationic textile dyes. The recorded Raman spectra are, in these cases, assigned to the complex formed by the humic acid and each of the species of interest. The obtained results revealed a significant dependence on the morphological and electronic properties of the HA-AuNPs with the synthesis procedure, and also a strong interaction between the nanoparticles and cationic dies. We conclude that HA-AuNP may provide a valuable approach for the spectroscopic characterization of environmentally relevant species and their chemical interaction with humic acids, through the use of surface enhanced Raman spectroscopy
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Dridi, Hamida. "Méthodologies pour la réalisation d'un substrat SERS à base de silicium poreux pour la détection de molécules chimiques et biologiques." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S012/document.
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Le travail de cette thèse porte sur la réalisation de substrats SERS (Surface Enhanced Raman Scattering) pour la détection d'espèce chimiques et biologiques. Il s'agit de mettre en place des méthodologies utilisant comme surface de départ celle d'une couche poreuse de silicium et un effet de Plasmon de surface induit par la présence d'un métal noble en général. Les spécificités des couches poreuses qui sont d'une part une rugosité nanométrique et d'autre part une porosité et donc une surface interne modulable ont une incidence directe sur la sensibilité de détection de molécules cibles. Nous avons développé dans ce manuscrit de thèse différentes méthodes d'élaboration de substrats SERS à base de couches poreuses de silicium. Nous avons envisagé deux voies, la première se base sur l'utilisation des nanoparticules d'or en solution colloïdale. La deuxième voie, plus originale, utilise le dépôt d'or par pulvérisation cathodique sur une couche poreuse préparée sur la face rugueuse de silicium. Des résultats SERS intéressants, concernant la détection de molécules chimique (Rhodamine 6G) et biologique (Albumine Sérum Bovin), ont été décrits et expliqués permettant d'envisager diverses solutions afin de les optimiserThe work of this thesis focuses on the realization of SERS substrates (Surface Enhanced Raman Scattering) for the detection of chemical and biological species. This is to implement the methodologies using as the starting surface of a porous silicon layer and a surface Plasmon effect induced by the presence of a noble metal in general. The specificities of the porous layers which are firstly a nanometer roughness and secondly a porosity and therefore an inner surface have a direct impact on the target molecule detection sensitivity. We have developed in this PhD thesis different substrates development methodologies SERS-based on porous silicon layers. We considered two ways, the first is based on the use of gold nanoparticles in colloidal solution. The second route, more original, uses the deposition of gold by sputtering on a porous layer prepared on the rough side of a silicon wafer. Interesting SERS results regarding the detection of chemical (Rhodamine 6G) and biological (Bovin Serum Albumin) molecules, have been described and explained for considering various solutions to optimize them
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Baker, Joshua Dale. "Near Single-Molecule SERS-Based Detection Using Ultrafiltered, Unfunctionalized Silver Nanoparticles." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1344523437.
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Alam, Md Khorshed. "Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest." Thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101573.
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This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest. Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls. The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively.