Dissertations / Theses: '(surface raman scattering) SERS'

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Harper, Mhairi. "DNA diagnostic assays using Surface Enhanced Raman Scattering (SERS)." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22401.

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DNA is the prerequisite for all biological life and its discovery has revolutionised the understanding of biomolecular interactions and disease expression. This has enabled significant improvements in patient diagnosis and medical treatment to be carried out. The advancements in technology and instrumentation have continually progressed this knowledge and continue to push the boundaries of diagnostic and clinical advancements. One effective way to achieve this is through application of dye labelled DNA sequences and metallic nanoparticle suspensions. This research details an understanding of the interaction between dye labelled oligonucleotides and silver nanoparticle surfaces, which generate strong surface enhanced Raman scattering (SERS) responses through specific hybridisation events which correlate to the presence of targeted sequences. During this study, the attraction of oligonucleotides onto metal nanoparticles was shown to be driven through the DNA nucleobases. Therefore, the increased exposure of the base groups within single stranded DNA sequences generated a higher affinity for metal surfaces which in turn produced stronger SERS responses when compared to double stranded DNA. This principle was utilised within a DNA detection assay to successfully demonstrate the presence of target DNA sequences. Two novel DNA detection assays were also investigated which utilised SERS to determine the presence of sequences relating to the methicillin resistant Staphylococcus aureus (MRSA) strain. A solution based detection method was developed through coupling a TaqMan assay with SERS. This combination enabled highly specific detection of clinically relevant sequences of MRSA to be obtained with 7 fM limits of detection achievable. The multiple detection of different genomic S. aureus strains was achieved through the molecularly specific and narrow emission spectral profiles obtained. A contrasting DNA detection strategy which relies upon the hybridisation of comple mentary sequences on a solid substrate surface was shown. Silver nanoparticles were functionalised with specific DNA sequences and a variety of SERS active molecules, enabling the selective detection of target sequences from nitrocellulose membranes. This thesis has exploited SERS to enable the specific identification of DNA sequences to be achieved via utilisation of silver nanoparticles. Through SERS, an insight into the interactions of DNA and silver nanoparticles surfaces has been gained as well as enhancing the sensitivity and specificity achievable within SERS detection assays.

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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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Yan, Bo. "Rationally designed substrates for SERS biosensing." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12894.

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Thesis (Ph.D.)--Boston University
The large electromagnetic field enhancement provided by nanostructured noble metal surfaces forms the foundation for a series of enabling optical analytical techniques, such as surface enhanced Raman spectroscopy (SERS), surface enhanced IR absorption spectroscopy (SEIRA), surface enhanced fluorescent microscopy (SEF), to name only a few. Critical sensing applications have, however, other substrate requirements than mere peak signal enhancement. The substrate needs to be reliable, provide reproducible signal enhancements, and be amenable to a combination with microfluidic chips or other integrated sensor platforms. These needs motivate the development of engineerable SERS substrate "chips" with defined near- and far-field responses. In this dissertation, two types of rationally designed SERS substrates - nanoparticle cluster arrays (NCAs) and SERS stamp - will be introduced and characterized. NCAs were fabricated through a newly developed template guided self-assembly fabrication approach, in which chemically synthesized nanoparticles are integrated into predefined patterns using a hybrid top-down/bottom-up approach. Since this method relies on chemically defined building blocks, it can overcome the resolution limit of conventional lithographical methods and facilitates higher structural complexity. NCAs sustain near-field interactions within individual clusters as well as between entire neighboring clusters and create a multi-scale cascaded E-field enhancement throughout the entire array. SERS stamps were generated using an oblique angle metal deposition on a lithographically defined piston. When mounted on a nanopositioning stage, the SERS stamps were enabled to contact biological surfaces with pristine nanostructured metal surfaces for a label-free spectroscopic characterization. The developed engineered substrates were applied and tested in critical sensing applications, including the ultratrace detection of explosive vapors, the rapid discrimination of bacterial pathogens, and the label-free monitoring of the enzymatic degradation of pericellular matrices of cancer cells.

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Shi, Chao. "Molecular fiber sensor probes based on surface enhanced Raman scattering (SERS) /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.

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Karabicak, Seher. "Application Of Surface-enhanced Raman Scattering (sers) Method For Genetic Analyses." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613130/index.pdf.

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Raman spectroscopy offers much better spectral selectivity but its usage has been limited by its poor sensitivity. The discovery of surface-enhanced Raman scattering (SERS) effect, which results in increased sensitivities of up to 108-fold for some compounds, has eliminated this drawback. A new SERS active substrate was developed in this study. Silver nanoparticle-doped polyvinyl alcohol (PVA) coated SERS substrate prepared through chemical and electrochemical reduction of silver particles dispersed in the polymer matrix. Performances of the substrates were evaluated with some biologically important compounds. The specific detection of DNA has gained significance in recent years since increasingly DNA sequences of different organisms are being assigned. Such sequence knowledge can be employed for identification of the genes of microorganisms or diseases. In this study, specific proteasome gene sequences were detected both label free spectrophotometric detection and SERS detection. In label free spectrophotometic detection, proteasome gene probe and complementary target gene sequence were attached to the gold nanoparticles separately. Then, the target and probe oligonucleotide-modified gold solutions were mixed for hybridization and the shift in the surface plasmon absorption band of gold nanoparticles were followed. SERS detection of specific nucleic acid sequences are mainly based on hybridization of DNA targets to complementary probe sequences, which are labelled with SERS active dyes. In this study, to show correlation between circulating proteasome levels and disease state we suggest a Raman spectroscopic technique that uses SERGen probes. This novel approach deals with specific detection of elevated or decreased levels of proteasome genes&rsquo
transcription in patients as an alternative to available enzyme activity measurement methods. First, SERGen probes were prepared using SERS active labels and specific proteasome gene sequences. Then DNA targets to complementary SERGen probe sequences were hybridized and SERS active label peak was followed.

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Faulds, Karen Jade. "Detection of drugs of abuse by surface enhanced Raman scattering (SERS)." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288636.

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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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Stewart, Shona Diane. "Surface enhanced Raman scattering on electrochemically prepared silver surfaces." Thesis, Queensland University of Technology, 1999.

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Andrade, Gustavo Fernandes Souza. "Caracterização espectroscópica da tiossemicarbazona do formilferroceno (TFF) através das técnicas SERS (Surface-Enhanced Raman Scattering) e Raman ressonante." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-13092006-164920/.

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Nesta dissertação o processo de adsorção da tiossemicarbazona do formilferroceno (TFF) em eletrodos de prata e ouro, em soluções aquosas 0,1 mol.L-1 de KCl e de acetonitrila. 0,1 mol.L-1 de NaClO4, foi caracterizado através da técnica espectroscópica SERS. Verificou-se através das variações espectrais que a adsorção da TFF ocorre através dos átomos N1 do grupo imínico e do S do grupo tiocarbonílico. Os processos faradáicos do TFF foram monitorados pela técnica SERS e de absorção no UV-visível. Os espectros SERS para potencial de -1,4 V (Ag/AgCl) sugerem a formação de um novo composto, produto de redução da TFF, o aminometilferroceno. Através da técnica de absorção no UV-visível verificou-se, neste potencial, o aparecimento no espectro de absorção de uma nova banda em 240 nm, atribuída à formação de tiouréia. A identificação deste dois produtos de redução indica que, para o composto TFF, o mecanismo geral de redução dos derivados de tiossemicarbazonas é obedecido. Nenhuma variação espectral, tanto utilizando a técnica SERS como a absorção no UV-visível, foi detectada durante o processo redox FeII/FeIII (E1/2=0,55 V). Os comportamentos de adsorção e faradáico da tiossemicarbazida (TSC), em eletrodo de prata em soluções aquosas neutra e ácida, foram estudados através da técnica SERS. Verificou-se que em meios neutro e ácido, a TSC está adsorvida na configuração cis para potenciais próximos de 0,0 V, interagindo com a superfície através do átomo de S do grupo tiocarbonílico e dos átomos de H ligados ao N1 hidrazínico, através da formação de pares iônicos com os ânions Cl- adsorvidos. Para potenciais mais negativos, os íons cloreto deixam a superfície e a TSC sofre reorientação, assumindo a conformação trans. Não foi observado através da técnica SERS nenhum processo faradáico em solução ácida para potenciais negativos, como havia sido proposto na literatura. A não redução do composto foi confirmada através da técnica de eletroforese capilar. Foi estudado o comportamento Raman ressonante da TFF, verificando-se a ocorrência de um mínimo no perfil de excitação experimental devido à interferência destrutiva das transições dos grupos tiossemicarbazona e ferrocenil. Os perfis de excitação teóricos foram calculados utilizando o método da transformada e os resultados dos ajustes obtidos indicam que existe considerável distorção dos modos do grupo ferrocenil na transição eletrônica em 312 nm, atribuída a n-p* do grupo tiossemicarbazona, caracterizando uma grande interação eletrônica entre os cromóforos da TFF. Para comparar o comportamento Raman ressonante do TFF com o do ferroceno, os espectros Raman ressonante deste composto foram obtidos. Verificou-se que o ferroceno apresenta, também, o efeito Raman anti-ressonante, mas as bandas vibracionais do ferroceno apresentam perfis distintos dos apresentados no composto TFF, indicando que a incorporação do grupo tiossemicarbazona no anel ciclopentadienil modifica a estrutura eletrônica do grupo ferrocenil.
In this dissertation, the adsorption process of the formylpyridine thiosemicarbazone (TFF) at silver and gold surfaces in aqueous and in acetonitrile solutions has been characterized by using the SERS (Surface-enhanced Raman Scattering) technique. It has been verified that TFF adsorbs through N1 and S atoms on the metallic surfaces. The faradaic processes of TFF have been monitored through the SERS and UV-visible absorption spectroscopies. The SERS spectra at -1,4 V (Ag/AgCl) suggest aminomethylferrocene as one of the reduction products of TFF. By using the UV-visible absorption technique, it has been verified, at this potential, a new band at 240 nm in the spectrum, which indicates the presence of thiourea. The observation of these two reduction products has confirmed that the general reduction mechanism for thiosemicarbazonas works for TFF. Neither SERS nor UV-vis spectral changes have been observed during the redox process of FeII/FeIII (E1/2= 0,55 V). The adsorption and faradaic processes of thisemicarbazide (TSC) at silver electrode have also been studied by SERS technique. It has been verified that, in acidic and neutral media, the TSC is adsorbed through a cis-configuration at a potential close to 0,0 V, showing an interaction of the S atom through bond formation with the surface and through the H atoms bonded to N1 via ion pair formation with the adsorbed Cl- anions. At more negative potentials, the chloride anions leave the electrode surface and the TSC changes to trans-configuration. No faradaic process has been observed as reported in the literature. This result has been confirmed by using the capillary electrophoresis technique. The resonance Raman effect of the TFF has been studied, and the excitation profiles of the bands have been shown as minimum, which indicates an electronic interaction between the two cromophores of the TFF (thiosemicarbazone and ferrocenyl). The theoretic excitation profiles have been calculated by using the transform method, and the results of the obtained adjustment has indicated that there has been a distortion of the ferrocenyl vibrational modes for an electronic transition at 312 nm, assigned to the n-p* of thiosemicarbazone moiety. This result has indicated a great interaction between the two cromophores of TFF. In order to compare the resonance Raman behavior of the TFF with that of the ferrocene, the resonance Raman spectra of the ferrocene have been obtained. It has been verified that the two compounds present an anti-resonant Raman effect, even though the bands have presented very different excitation profiles from those observed in the TFF, which indicates that the incorporation of the thiosemicarbazone group into the ciclopentadienyl has changed the electronic structure of the ferrocenyl group.

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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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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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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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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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Gisbert, Quilis Patricia. "Optical detection and structural analysis of DNA via direct surface-enhanced Raman scattering." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/586257.

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Un nou mètode basat en la espectroscopia Raman intensificada per superfície (SERS) és implementat en aquesta tesi per a la detecció òptica i anàlisi estructural d'àcids nucleics. Aquest mètode es basa en la utilització de partícules de plata carregades positivament, com a substrats plasmònics per a l'anàlisi d'ADN en solució per SERS. Aquesta estratègia s'ha aplicat amb èxit per a la detecció ultrasensible de mutacions puntuals en el gen K-Ras, les quals són habitualment analitzades amb objectius diagnòstics, especialment en el càncer colorectal. En paral·lel amb aquest estudi, l'impacte estructural d'aquestes partícules amb l'ADN s'analitza amb profunditat.
Un nuevo método basado en la espectroscopía Raman intensificada por superficie (SERS) se implementa en esta tesis para la detección óptica y análisis estructural de ácidos nucleicos. Este método se basa en la utilización de partículas de plata cargadas positivamente, como sustratos plasmónicos para el análisis de ADN en solución por SERS. Esta estrategia se ha aplicado con éxito para la detección ultrasensible de mutaciones puntuales en el gen K-Ras, las cuales son comúnmente analizadas con objetivos diagnósticos, especialmente en el cáncer colorectal. En paralelo con este estudio, el impacto estructural de estas partículas con el ADN se analiza con profundidad.
A novel approach based on surface-enhanced Raman scattering (SERS) for the label-free optical detection and structural analysis of nucleic acids is implemented in this dissertation. The method relies on the use of positively-charged silver nanoparticles as plasmonic substrates for SERS analysis of DNA in solution. This strategy is successfully applied for the sensitive detection of clinically relevant point mutations in the K-Ras gene, which are routinely screened for diagnostic purposes, especially in colorectal cancer. Along this study, the impact of the cationic nanoparticles on the structural features of the interacting DNA molecules is extensively investigated.

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Morlà, Folch Judit. "Direct Label-free Surface-Enhanced Raman Scattering Analysis of Nucleic Acids." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/454761.

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La recerca s'ha realitzat en el context de l'espectroscòpia “Surface-Enhanced Raman Scattering” (SERS) per a l'anàlisi d'àcids nucleics. SERS és una tècnica analítica de gran abast que combina l'especificitat estructural i alta flexibilitat experimental de l'espectroscòpia Raman amb l'extremada sensibilitat proporcionada per l'amplificació del senyal òptic per part de la nanoestructura metàl•lica. La caracterització dels àcids nucleics (ANs) s'ha convertit en una meta important en molts camps. En general, els ANs es troben en baixes quantitats de manera que la sensibilitat representa un requisit clau per a la seva detecció. En aquest sentit, l'espectroscòpia SERS es pot considerar una poderosa eina per a l'anàlisi de ANs, donat a la seva extraordinària sensibilitat i a la rica informació estructural proporcionada. Fins ara, l'anàlisi SERS de ANs ha estat en gran part restringit a enfocaments indirectes, perdent les informacions estructurals de l'adquisició directa de la petjada vibracional. En aquest sentit, nanopartícules de plata carregades positivament recobertes amb espermina, van ser dissenyades específicament per a l'anàlisi de ANs amb SERS directe. Mitjançant l'ús d'aquest substrat s'assegura la interacció electrostàtica entre els ANs i els col•loides produint espectres SERS intensos i altament reproduïbles a nivell ultrasensible. Aquest mètode directe, sense necessitat d'afegir marcadors i altament sensible es va implementar amb èxit en diverses aplicacions d'interès biològic, incloent la identificació i quantificació de nucleobases amb modificacions, en simple i doble cadenes d'ADN, quantificació de la composició de nucleobases en ADN curts i en ADN genomic, i classificació vibracional de ARNs petits estructuralment similars. En resum, aquesta tesi demostra el gran potencial analític d'aquest nou mètode directe, obrint noves vies pel futur desenvolupament d'una tècnica analítica ràpida, de baix cost i alt rendiment per l’anàlisi d'àcids nucleics.
La investigación se ha realizado en el contexto de la espectroscopia “Surface-Enhanced Raman Scattering” (SERS) para el análisis de ácidos nucleicos. SERS es una técnica analítica de gran alcance que combina la especificidad estructural y alta flexibilidad experimental de la espectroscopia Raman con la extremada sensibilidad proporcionada por la amplificación de la señal óptica por parte de la nanoestructura metálica. La caracterización de los ácidos nucleicos (ANs) se ha convertido en una meta importante en muchos campos. En general, los ANs se encuentran en bajas cantidades de modo que la sensibilidad representa un requisito clave para su detección. En este sentido, la espectroscopia SERS se puede considerar una poderosa herramienta para el análisis de ANs, dado a su extraordinaria sensibilidad y la rica información estructural proporcionada. Hasta ahora, el análisis SERS de ANs ha sido en gran parte restringido a enfoques indirectos, perdiendo las informaciones estructurales de la adquisición directa de la huella vibracional. En este sentido, nanopartículas de plata cargadas positivamente recubiertas con espermina, fueron diseñadas específicamente para el análisis de ANs con SERS directo. Mediante el uso de este sustrato se asegura la interacción electrostática entre los ANs y los coloides produciendo espectros SERS intensos y altamente reproducibles a nivel ultrasensible. Este método directo, sin necesidad de añadir marcadores y altamente sensible se implementó con éxito en diversas aplicaciones de interés biológico, incluyendo la identificación y cuantificación de nucleobases modificadas, en simple y doble cadena de ADN, cuantificación de la composición de nucleobases en ADN cortos y en el ADN genómico, y clasificación vibracional de ARNs pequeños estructuralmente similares. En resumen, esta tesis demuestra el gran potencial analítico de este nuevo método directo, abriendo nuevas vías para el futuro desarrollo de una técnica analítica rápida, de bajo coste y alto rendimiento para análisis de ácidos nucleicos.
The research has been carried out in the context of Surface-Enhanced Raman Scattering (SERS) spectroscopy for nucleic acids analysis. SERS is a powerful analytical technique that combines the structural specificity and high experimental flexibility of Raman spectroscopy with the extremely high sensitivity provided by the metal nanostructure amplification of the optical signal. Characterization of nucleic acids (NAs) has become a major goal in fields such as genetics or drug discovery. NAs are usually found in low amounts which require extremely sensitive techniques to be detected. Sensitivity represents a key requirement for their implementation into easy-to-use, cost-effective, rapid and high accuracy NA sensors. In this regard, the extraordinary sensitivity, in combination with the rich structural information provided by the Raman spectra, turned SERS into a powerful tool for the analysis of NAs. SERS analysis of NAs has been largely restricted to indirect approaches, dismissing the exquisite structural information provided by the direct acquisition of the biomolecular vibrational fingerprint. In this regard, positively charged silver nanoparticles coated with spermine were specifically designed for direct label-free SERS analysis of nucleic acids. By using these cationic nanoparticles the electrostatic interaction between NAs and the colloids is ensured yielding intense and highly reproducible SERS spectra at the ultrasensitive level. This highly sensitive label-free approach was successfully implemented in various applications of biological interest including identification and quantification of chemically-modified nucleobases in single and double stranded DNA, quantification of nucleobase composition in short and genomic DNA, and vibrational classification of structurally similar small RNA. In summary, this thesis demonstrates the tremendous analytical potential of this novel direct SERS method for nucleic acids analysis, opening new ways for the future development of a fast, low-cost, and high-throughput analytical technique for nucleic acids analysis.

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Brolo, Alexandre Guimar aes. "Surface-enhanced Raman scattering, SERS, studies of pyrazine adsorbed on polycrystalline and single crystal electrodes." Phd thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://hdl.handle.net/10012/221.

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Brolo, Alexandre Guimaraes. "Surface-enhanced Raman scattering, SERS, studies of pyrazine adsorbed on polycrystalline and single crystal electrodes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30589.pdf.

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Dogan, Uzeyir. "Preparation And Characterization Of Surface Enhanced Raman Scattering Substrate Through Electro Deposition Of Silver-pedot Film On Ito Glass Surface." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613667/index.pdf.

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Detection of chemicals is a vital part of chemistry. For this reason, many detection systems are developed by scientists and every detection system has its own advantages. Raman spectroscopy is one of these detection systems having many advantages. However, this technique suffers from low signal intensity disadvantage. By developing a well prepared substrate, this problem can be easily solved
moreover, even single molecule detection can be possible. In this study, a novel surface enhanced Raman scattering (SERS) substrate was prepared in two steps: In the first step, ethylenedioxythiophene (EDOT) monomer was polymerized electrochemically onto indium tin oxide (ITO) coated glass. In the next step, silver ions were reduced electrochemically onto surface prepared in the previous step.In the substrate preparation part, the reduction potential of silver ion, the concentration of silver ions in solution, the polymer film thickness and reduced silver amount on substrates were optimized to get the best SERS performances from substrates. The prepared substrates were characterized by cyclic voltammetry (CV), ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) attached to SEM. In the SERS performance investigation part, homogeneity and the shelf life of the prepared silver-PEDOT substrates were tested. Homogeneity is very important in terms for the applications of Raman technique in quantitative analysis since most of the reported substrates are lack homogeneity consideration, our study will be an important contribution to the literature. The stability of the substrate was investigated for a period of one month. The very small change in the signal at the end of one month indicated that the substrate can be used even longer time with high efficiency. In all the studies, brilliant cresyl blue (BCB) is used as a model compound. Some important Raman active chemicals, namely, rhodamine 6G (R6G) and 4-mercapto benzoic acid (4-MBA) were detected by using the prepared substrates.

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Santos, Júnior Vianney Oliveira dos. "Estudos SERS (Surface-Enhanced Raman Scattering) em meio de Líquido Iônico BMIPF6 usando eletrodo de prata." reponame:Repositório Institucional da UnB, 2007. http://repositorio.unb.br/handle/10482/2860.

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Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, 2007.
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Líquidos iônicos a temperatura ambiente (LI) tem tido aplicação cada vez maior em várias áreas da Química, devido às diferentes propriedades que o mesmo oferece em relação aos solventes convencionais. LI's derivados do cátion BMI+ se destacam devido as suas propriedades físico-químicas singulares, como alta condutividade elétrica e uma larga janela eletroquímica. Em contraste com outras técnicas espectroscópicas, O efeito SERS é uma técnica extremamente poderosa para estudos de interfaces eletrodo/solução em sistemas eletroquímicos, devido a sua alta sensibilidade e à possibilidade de trabalhar com interfaces sólido-líquido e em meio aquoso. Nesse trabalho foram obtidos os espectros SER in situ do BMIPF6 adsorvido em eletrodo de Ag para vários potenciais aplicados, bem como da piridina adsorvida na interface Ag/BMIPF6. Obteve-se também os espectros SER da solução aquosa de BMICl em vários pH's, sendo proposta uma atribuição vibracional completa para o mesmo. Os resultados obtidos na adsorção da piridina mostram que a interface Ag/BMIPF6 pode ser usada com sucesso para o estudo SERS de sistemas eletroquímicos, tendo se caracterizado o comportamento da piridina no meio com a variação do potencial aplicado. Observou-se nos espectros SER do BMIPF6 adsorvido sobre eletrodo de Ag a geração eletroquímica de um derivado carbeno e a variação da geometria de adsorção em potenciais característicos. Os experimentos SERS do BMICl em meio aquoso mostraram que seu comportamento depende do pH do meio, com a geração eletroquímica de um derivado radical neutro em pH básico. Os resultados obtidos mostram que o efeito SERS é uma ferramenta poderosa para o estudo de sistemas eletroquímicos em líquidos iônicos, permitindo a obtenção de uma série de informações sobre processos eletroquímicos na superfície do eletrodo, como mudanças de geometria de adsorção e formação de pares iônicos, além de informações estruturais sobre as espécies adsorvidas. _______________________________________________________________________________________ ABSTRACT
Room Temperature Ionic Liquids (RTIL) has had increasingly application in different areas of the Chemistry, due to its advantageous physical-chemical properties in relation to other conventional solvents. BMI cation derived RTILs got relevance due its singular physical-chemical properties, like a good electric conductivity and a wide electrochemical window. In contrast with others spectroscopic techniques, SERS is a extremely powerful technique for studies of electrode/solution interface in electrochemical systems, because of its high sensitivity and the possibility of working with solid-liquid interfaces and in aqueous media. In this work SER spectra were obtained in situ for adsorbed BMIPF6 on Ag electrode for several applied potentials, as well the ones of adsorbed pyridine on the Ag/BMIPF interface. We also show the SER spectra of BMICl 6 aqueous solution at several pHs, being proposed its complete vibrational assignment. The results about the adsorption of pyridine show Ag/BMIPF 6 interface can be successfully used for SERS studies of electrochemical systems. This results have also characterized the electrochemical behavior of pyridine at different applied potentials. It was observed in the SER spectra of BMIPF6 adsorbed on Ag electrode the electrochemical generation of a BMI carbene and changes of the adsorption geometry at characteristic potentials. The SERS study of BMICl in aqueous media has shown that its behavior depends on the pH of media, with the electrochemical generation of one neutral radical derived in alkaline media. The results show that the SERS effect is a powerful technique for the study of electrochemical systems in RTIL, allowing the attainment of a very kind of information about electrochemical processes occurring at electrode surface, like changes of adsorption geometry and ionic pairs formation, besides structural information about the adsorbed molecules.

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Watling, Kym Marjorie, and n/a. "Spectroelectrochemical Studies of Surface Species in the Gold/Thiosulfate System." Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20081024.164504.

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This thesis presents results of studies using the technique of surface-enhanced Raman scattering (SERS) spectroscopy to investigate surface processes occurring on gold during electrochemical experiments in thiosulfate solutions and during leaching in ammoniacal copper(II) thiosulfate systems. The gold SERS electrode was characterised using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). SEM investigations of the SERS activated gold surface showed the presence of electrodeposited dendrites with nanoscale features. XRD studies of the dendrites showed them to be polycrystalline with a large proportion of Au(111). Rotating disk electrode (RDE) studies of polished and SERS electrodes were undertaken in order to clarify the electrochemistry of various thiosulfate systems. The ex situ techniques of XPS and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used to determine the presence of sulfur, copper and nitrogen on leached or electro-oxidised surfaces. Voltammetric methods were used to determine sulfur and copper surface coverages at various potentials in sulfide, thiosulfate and ammoniacal copper(II) thiosulfate media. The electro-oxidation of sulfide was examined as a model system in order to identify spectral features and coverage associated with various potential-dependent sulfur layers. In the hydrogen evolution region, a surface layer formed by underpotential deposition in acid and basic media was characterised by a gold-sulfur stretching band, Au-S, attributed in the literature to a monoatomic stretching mode of sulfur bonded to gold. The surface coverage in this potential region was limited to 0.35 ML, representing adsorption in a (3x3)R30 structure. Bands were found to be absent that would have indicated the adsorption of SH species as has been reported in the literature. A facile change in the position of the Au-S band with potential, unaccompanied by Faradaic processes, was seen when the adsorbed (3x3)R30 sulfur layer was examined in a sulfide-free solution. This may indicate a change in sulfur adsorption sites with potential in the hydrogen evolution region. At potentials above the S II/S0 reversible value in sulfide solutions, the surface coverage increased and S-S bands were observed, indicating the formation of an adsorbed polysulfide species, Au-Sn. A change in the position of the Au-S band was seen to accompany the formation of the S-S bands. As coverage further increased, bands due to S-S-S bending, S-S-S, developed that were characteristic of cyclo octasulfur, S8. On removal from sulfide solution and rinsing, a characteristic SERS spectrum was observed ex situ. The spectrum showed a characteristic S-S at 460 cm-1 and Au-S at 325 cm-1 and was assigned to an adlayer of S8 adsorbed on gold in a crown configuration, Au S8. Gold was polarised in thiosulfate solutions at a potential at which gold dissolution is known to occur. In situ SERS spectra showed bands characteristic of S-S bonding and Au2S to occur after 1 hr for thiosulfate with sodium and ammonium counter-ions and for both systems in the presence of ammonia. XPS studies of polished gold held in sodium thiosulfate under these conditions showed S 2p binding energies corresponding to metal sulfide and pyritic sulfur, S22-. After 72 hrs at the mixed potential in air saturated sodium thiosulfate, SERS investigations showed a spectrum with Au-S8 characteristics. XPS studies on a polished electrode under these conditions showed a third type of S 2p binding with a binding energy between that of pyritic sulfur and S8. The sodium thiosulfate system showed an adsorbed tetrathionate-like surface species, Au-S4O6, to be present at the mixed potential and to disappear with increased potential prior to the formation of bulk S8 via an Au-S8 intermediate. In the presence of the ammonium cation at high potentials, Au-Sn bands appear in the presence of a more intense and broad Au-S characteristic of gold sulfide, Au2S. This was assigned to a mixed gold sulfide/polysulfide phase, Au2S/Sn. With addition of ammonia, the surface species Au S4O6, Au2S/Sn and, tentatively, adsorbed NH3 were observed above the mixed potential. For gold in air-saturated copper(II) ammoniacal thiosulfate media, bands due S-S at 382 cm-1 and symmetric S-O stretching, symS-O, at 1017 cm-1 developed during leaching at the mixed potential. These modes diminished and, when rinsed and examined in water, were replaced by a single band at 255 cm 1 assigned to a metal sulfide stretch. In typical leach solutions, sulfur and copper coverages showed a 2:1 atomic ratio after leaching for 16 h. Ex situ ATR and XPS studies showed that ammonia was adsorbed to a surface copper sulfide. Kinetic studies using atomic absorption spectroscopy (AAS) to measure gold in solution showed that the ammoniacal copper(II) thiosulfate leaching solution exhibited higher dissolution rates in the presence of the sodium counter ion than the ammonium. Thiourea as an additive to thiosulfate solutions was seen to disrupt S-S bonding in both Au-S8 and Au2S/Sn surface structures.

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Oliveira, Karolyne Vilela de. "Desenvolvimento de substrato para uso com efeito Raman intensificado por superfície (SERS – Surface-Enhanced Raman Scattering) e aplicações para compostos modelo." reponame:Repositório Institucional da UnB, 2015. http://dx.doi.org/10.26512/2015.12.D.20361.

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Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, 2015.
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Neste trabalho foram preparados dois substratos com atividade SERS (surface-enhanced Raman scattering), baseados na dispersão de nanopartículas de prata em solução aquosa (AgNPs/Coloide) e em gel de agarose (AgNPs/Agar). Esses substratos foram caracterizados por MET e espectroscopia UV-vis. Ambos os substratos foram também investigados pelo efeito SERS, registrando-se 100 espectros em triplicata empregando o modo de mapeamento Raman numa região de 20x20 µm. Os diâmetros médios das AgNPs nas amostras de AgNPs/Coloide e AgNPs/Agar foram de 8 nm e 19 nm, respectivamente. Os espectros UV-vis desses materiais revelam que as AgNPs/Agar apresentam ressonâncias de plasmon de superfície na região de 600 nm. A adsorção da rodamina 6G (R6G) foi investigada para ambos os substratos, para concentrações entre 10-8 M e 10-5 M, por excitação SERS em 632,8 nm. As intensidades SERS da R6G nas AgNPs/Agar foram ca. 10 vezes mais fortes que aquelas apresentadas para a R6G adsorvida nas AgNPs/Coloide. As isotermas de adsorção obtidas para ambos os substratos foram bem ajustadas a isotermas de Langmuir com constantes de adsorção e energias livres de Gibbs de adsorção semelhantes, características de adsorção química. As AgNPs/Agar também foram investigadas como um substrato SERS-ativo para a adsorção de azul de metileno (MB), cristal violeta (CV) e benzotriazolato (BTA). Os resultados SERRS para o MB mostraram sinais de monômeros e dímeros de MB. Os resultados também mostraram que R6G e CV adsorvem na superfície das AgNPs/Agar formando pares iônicos com os íons cloreto adsorvidos usados para promover agregação, enquanto que o MB e BTA adsorvem quimicamente na superfície das AgNPs formando ligações Ag-N. Curvas de intensidade SERS vs. concentração do adsorbato em solução foram usadas para obter isotermas de adsorção. Em todos os sistemas investigados os dados experimentais apresentaram razoável ajuste para isotermas de Langmuir com constante de adsorção e energia livre de Gibbs de adsorção compatível com adsorção química (< -30 kJ.mol-1). Os resultados (SERS/SERRS) para R6G, MB e CV, em concentração de 10-8 M, adsorvidos em AgNPs/Agar mostraram que os sinais SERS/SERRS de moléculas únicas desses adsorbatos foram observados, mostrando que o material AgNPs/Agar obtido é um substrato adequado para a investigação SERS de adsorbatos em concentrações muito baixas.
Two different SERS (surface-enhanced Raman scattering) substrates have been prepared based on silver nanoparticles (AgNPs) dispersed in water solution (AgNPs/Colloid) and in agarose gel (AgNPs/Agar). The materials were characterized by TEM and UV-vis spectroscopy. Both substrates were also investigated by SERS by recording 100 spectra in triplicates, using the Raman mapping procedure in an area of 20x20 µm. The mean diameters of the AgNPs in these substrates were 8 nm and 19 nm, respectively. The UV-vis spectra of these materials show that the AgNPs/Agar present AgNPs aggregates with surface plasmon resonances in the region of 600 nm. The adsorption of Rhodamine 6G (R6G) at concentrations ranging from 10-8 M to 10-5 M on both substrates was investigated by SERS excitation at 632.8 nm. The SERS intensities of R6G on the AgNPs/Agar were ca. 10 times stronger than those displayed for R6G adsorbed on the AgNPs/Colloid. Adsorption isotherms obtained for both substrates were well fitted to Langmuir isotherms with similar adsorption constants and free Gibbs adsorption energy, characteristic of chemical adsorption. The AgNPs/Agar was further investigated as a SERS-active substrate for the adsorption of Methylene Blue (MB), Crystal Violet (CV) and benzotriazolate (BTA). The SERRS results for MB have shown signals from MB monomers and dimers. The results have also shown that R6G and CV adsorb on the AgNPs/Agar surface forming ion-pairs with the adsorbed chloride ions used to promote the AgNPs aggregation, while MB and BTA adsorb chemically on the AgNPs surface forming Ag-N bonds. Curves of SERS intensity vsadsorbate concentration in solution were used to obtain adsorption isotherms. In all investigated systems the experimental data presented reasonable fitting to Langmuir isotherm with adsorption constants and free Gibbs adsorption energy compatible with chemical adsorption (< -30 kJ.mol-1). The results (SERS/SERRS) for R6G, MB and CV at 10-8 M concentration adsorbed on AgNPs/Agar have shown that SERS/SERRS signals from single molecules of these adsorbates were observed, showing that the AgNPs/Agar material obtained is a suitable substrate for SERS investigation of adsorbates at very low concentrations.

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Koksel, Bahar. "The Use Of N-polyethereal Polypyrroles In Preconcentration And Surface Enhanced Raman Scattering Studies." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610495/index.pdf.

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Polypyrroles containing polyether pseudocages (PI, PII, PIII) have been synthesized via chemical oxidation of 1,5-bis(1,1-pyrrole)-3-oxabutane (MI), 1,8- bis(1,1-pyrrole)-3,6-dioxahexane (MII), and 1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane (MIII) using anhydrous FeCl3 in CHCl3. Because as obtained polymer resins did not give any response toward any cations, they were reduced (undoped) using chemical reducing agents. Tetrabutylammonium hydroxide (TBAOH) was found to be more effective in undoping to obtain more reproducible and reusable polymer resins. It was investigated whether the undoped polymer resins were used for the extraction of rare earth metal ions from the aqueous medium. Among them, only PIII resin can extract La(III), Eu(III) and Yb(III) from their aqueous solutions and can be employed for the preconcentration of these metal ions. For batch extraction of La(III), Eu(III) and Yb(III) at neutral pH values, percent recoveries of 98.0, 90.7 and 87.3, respectively, has been obtained by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) technique. The sorption capacity is found as 1.3 mg of La(III) per gram of PIII resin. The PIII resin could be reused at least five times without significant change in its sorption capacity. PIII has also been synthesized via electrochemical method to be used in the preparation of Surface Enhanced Raman Scattering (SERS) active substrate. PIII has been polymerized on Indium Tin Oxide (ITO) glass by using constant potential electrolysis. In an electrolyte solution containing 0.05M tetrabutylammonium perchlorate (TBAP), 1.2 V vs. Ag wire (oxidation potential of MIII) was applied for coating and then silver particles were deposited on the surface of PIII coated ITO electrode by reducing Ag(I) in monomer free electrolyte solution electrochemically. As an alternative, another SERS substrate was prepared electrochemically by depositing silver particles directly on ITO glass. The performances of prepared ITO-PIII-Ag and ITO-Ag SERS substrates were evaluated with dilute solutions of brilliant cresyl blue (BCB), crystal violet (CV), para amino benzoic acid (PABA), nicotine and nicotinic acid.

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Kumarswami, Neelam. "Development of a multiplexing biosensor platform using SERS particle immunoassay technology." Thesis, University of Bedfordshire, 2014. http://hdl.handle.net/10547/321094.

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The purpose of this study is to demonstrate the ability of surface enhanced Raman scattering (SERS) active particles to enable multiplexed immunoassays in a lateral flow format for point of care (POC) testing. The SERS particles used for this study are chemically active glass coated gold particles, containing tracer molecules which in principle can be chosen to provide Raman Spectra with unique features allowing multiple tracers to be simultaneously measured and distinguished without interference between each other. Lateral flow immunoassay technology is the important part of this study and can be conveniently packaged for the use of other than highly skilled technicians outside of the laboratory. A well-known (single channel - simplex) device for the pregnancy test is a typical example of the lateral flow assay. Similar formats have been/are being developed by others for a range of POC applications – but most diagnostic applications require simultaneous determination of a range of biomarkers and multiplexed assays are difficult to achieve without significant interference between the individual assays. This is where SERS particles may provide some advantages over existing techniques. Cardiac markers are the growing market for point of care technology therefore biomarkers of cardiac injury (Troponin, myoglobin and CRP) have been chosen as a model. The object of the study is to establish the proof of concept multiplexing assay using these chosen biomarkers. Thus, initially all different particles were characterised in single and mixture form. Also development of conjugate chemistry between antibodies for each analyte that have been purchased from commercial sources and SERS particles were analysed using different conditions like buffer, pH and antibody loading concentration to get the optimum intensity. The selected SERS particles and their conjugates were tested for size, aggregation and immune quality using a range of techniques: ultraviolet-visible (UV/Vis) absorption spectroscopy, dynamic light scattering (DLS) and lateral flow assay. These characterisations methodologies gave the understanding of optimum conditions of the each conjugates and individual’s behaviour in mixture conditions as well. After the characterisation all conjugates were tested singularly on the lateral flow assay using buffers and serum. The results of this single analyte immunoassay explained the individual’s bioactivity on the lateral flow strip. Further in study, multiplex assay have been demonstrated in serum. These outcomes have described each candidate characteristic in a mixture form on the lateral flow strip. In order to get the optimum Raman intensity from multiplex assay, the detection and capture antibodies loading concentrations were tuned in the assay. Later on different combinations (high, medium and low concentrations) of all three analytes were analysed and has found some interferences in multiplex assay. To investigate these issues various aspect were considered. First of all, different possibilities of non-specific interactions between the co-analytes and antibodies were tested. In addition, steric hindrance and optical interference investigations were performed via several assays and analysis using Scanning electron microscopy. The outcomes have confirmed related optical interferences. Therefore other assay (wound biomarkers) established to eliminate the interferences. In summary, the works reported here have built and test the equipment and necessary reagents for individual assays before moving on the more complicated task. In addition, the entire study has given a deep knowledge of multiplex assay on a single test line including the investigation of the issues for selected cardiac biomarkers and their applications in the future.

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Oo, Swe Zin. "Design, fabrication and optimization of large area chemical sensor based on Surface-Enhanced Raman Scattering (SERS) mechanism." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/383010/.

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In recent years there has been an increasing interest in analysis and identification of complex molecules for the medical diagnostics, pharmaceutical research and homeland security applications. If these molecules are present in high concentration, a technique known as Raman spectroscopy can be utilized. Unfortunately, only one in every 1012 photon incidence on molecule undergoes Raman scattering resulting in weak Raman absorption. An efficient technique to overcome this limitation is to utilize surface-enhanced Raman scattering (SERS) whereby molecules are placed on the surface of nanostructured metallic substrate which performs the function of transducting photons into and out of the molecules. SERS extends the scope of Raman scattering to detect molecules at low concentrations to few/single molecule level. Previously the ‘KlariteTM’ substrate consisting of an inverted array of square based pyramidal nanostructures patterned onto a Silicon substrate has been demonstrated to afford highly reproducible SERS signals with approximately 107 enhancement factor. In this report, the effect of geometrical parameters associated with the inverted pyramidal array on SERS effect for sensing applications was investigated. Geometrical parameters studied include pitch length, pit size, aspect ratio of the base of pyramid and fill factor. 3D computational modelling based on Rigorous Coupled Wave Analysis (RCWA) is used to bridge with theory. From these observations, the geometrical parameters of inverted pyramid nanostructures have been optimized for better sensing ability. A test chip is fabricated for the purpose of performing a matrix experiment, allowing deconvolution of geometrical variables: lattice pitch (1000nm-3000nm), pit size (500nm-2500nm), pit aspect ratio [width to length]. Fabrication steps include electron-beam lithography, anisotropic wet etching and metallization. Computational and experimental reflectometry systems were applied to enable the identification and analysis of a variety of dispersive features including propagating surface plasmons, localized surface plasmons and diffraction dispersion. From the study of inverted pyramid, plasmonic behaviors are observed: 1. the surface plasmon polariton depends strongly on polarization. 2. Highly dispersive features arising from simple surface diffraction effects appear insensitive to polarization state. 3. As the pit size gets bigger, the diffraction efficiency decreases but the wavelength/angular position remain the same. 4. Diffractive features are relatively sharp and clearly defined (narrow bandwidth), and are highly dependent on lattice pitch. Hence they move in wavelength and angle (e.g. highly dispersive) as pitch is varied. These features relate to the coupling of light into or out of the sensor chip. 5. Localized surface plasmons have characteristic of small wavelength shift over wide angular range (low dispersion), and are generally broader in bandwidth. Plasmon features can conclusively be identified over diffractive features by making comparisons between simulations ‘with’ and ‘without’ the top metal coating. In order to derive the optimal geometry for SERS sensor, a highly stable test molecule which is known to form a monolayer coating on gold is required. For this purpose benzenethiol was used as standard in this work. Devices were tested using a Renishaw Invia Raman system. The main wavelength of interest here is 785nm where this laser is readily available and compatible with the end user Raman system. Full details of the optical and Raman measurements are carried out on the silicon test platform. Results show that the averaged SERS enhancement factor was only slightly dependent upon lattice pitch, but was highly dependent on pit size and aspect ratio. Density of the pits plays a further role simply by increasing the number of pits/unit area and so provides extra increase in SERS signal. The experimental data shows this is not simply a surface area dependent effect, but the optimal SERS signal can be obtained by close packing as tightly as possible pits of the optimal size. Minimum spacing (between adjacent pits) of 250nm is found to give the highest SERS enhancement. The optimal aspect ratio was found to be 1:1.2 and the optimal pit size determined to be 1000nm. This new optimized design shows 10-fold improvement in sensitivity compared to current available benchmark Klarite. The study has also explored the possibility of replicating the optimized design to a cost effective and disposable polymer for the purpose of mass production. This was carried out using nanoimprint lithography. The replicated plastic sensor is comparable to the benchmark silicon Klarite. As a proof of principle, the qualitative performance in two demonstrator molecules such as ibuprofen and melamine has been carried out. The disposable plastic sensor was demonstrated for the possibility of dual sensing mechanisms such as surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS). The sensitivity of plastic sensor using SPR mechanism is 225.83nm/RIU on thiol molecule. The work has also been carried out for an alternative SERS sensor design by changing the sidewall profile to 90˚ angle from (100) silicon etched plane. Changing the sidewall profile makes impact on the plasmonic behaviour. The straight sidewalls are favourable to the localized plasmon mode. The structures with slope sidewalls are favourable to both localized and propagating plasmons inside the cavities. This work was conducted as part of the FP7 ‘’PHOTOSENSE’’ consortium project.

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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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26

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 superfície
Organic 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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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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Sanci, Rukiye. "Synthesis Of Colloidal Silver Particles With Different Sizes By Seeding Approach For Surface Enhanced Raman Scattering (sers) Studies." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611076/index.pdf.

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In this study, silver nanorods and nanospheroids were prepared both in aqueous solution and on the surface of glass slides through seed-mediated growth approach at room temperature and used as a surface enhanced Raman scattering (SERS) substrate. The synthesis of metallic nanorods was started with the production of silver nanospheres as seed utilizing sodium borohydride and trisodium citrate as reducing and capping agents, respectively. These seeds were then added to a growth solution containing additional silver salt, ascorbic acid and cetyltrimethylammonium bromide (CTAB.) Nanorod preparation conditions were first optimized in solution phase. The plasmon absorption of the formed nanocrystals was monitored by UV-Visible spectrometry. The largest red shift in the longitudinal plasmon resonance absorption of silver nanostructures was tried to be achieved in order to realize the highest electromagnetic enhancement in Raman measurements. The images of the formed nanorods were recorded using field emission scanning electron microscopy (FE-SEM). The optimized colloidal growth conditions were adopted for the growth of nanorods on the surface of the glass substrate. Sol-gel coated glass slides were used in order to increase the porosity on the surface for an effective seeding process. We reported the development of a novel SERS substrate prepared by growing silver nanorods directly on the surface of glass surface without using any linker molecule. The SERS performances of the nanorod growth surfaces were evaluated with crystal violet (CV), brilliant cresyl blue (BCB) and benzoic acid (BA). Some modifications such as the increase in the AgNO3 concentration in the growth solution and the addition of hydrocarbons to the growth solution were investigated for the enhancement of the SERS signal. The intense spectra obtained for the model compounds demonstrated the efficiency of the prepared substrate for the SERS enhancement and its potential as a SERS detection probe for chemical and biological analysis.

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Vabbilisetty, Pratima. "Fabrication and Characterization of Substrate Materials for Trace Analytical Measurements by Surface Enhanced Raman Scattering (SERS) Spectroscopy Technique." Connect to resource online, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1231794465.

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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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Keser, Sezen Lutfiye. "Preparation Of Gold Decorated Cobalt-silica Core-shell Nanoparticles For Surface Enhanced Raman Scattering Applications." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612383/index.pdf.

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Bringing together several materials into a single nanoparticle is an attractive way to design systems that exhibit diverse physical and chemical properties. Cobalt nanoparticles are extensively used in magnetic separation, ferrofluids, and magnetic storage media. The deposition of gold nanoparticles onto cobalt core significantly affects their optical properties due to the introduction of surface Plasmon. Here the synthesis of gold nanoparticles decorated cobalt-silica nanoparticles are reported for the first time. Their optical and magnetic properties and capacity as a surface enhanced Raman scattering (SERS) substrate were investigated. This nano-material is of particular interest as a dual agent allowing both magnetic separation and SERS detection. The synthesis involves three steps: i) synthesis of Co nanoparticles
ii) deposition of a silica shell around the Co core and introduction of amine functional groups on the surface
iii) decoration of the surface with gold nanoparticles. Co nanoparticles were prepared in an inert atmosphere in the presence of capping and reducing agents. Size of the cobalt nanoparticles was varied by changing the concentration of the capping agent. Since cobalt particles are easily oxidized, they were coated with silica shell both to prevent oxidation and allow further functionalization. Silica coating of the particles were performed in water/ethanolic solution of tetraethyl orthosilicate (TEOS). Thickness of silica coating was controlled by varying the concentrations of TEOS. Besides, by adding 3-aminopropyl-triethoxysilane (APTS) to the reaction medium, primarily amine groups were introduced on the silica surface. For further modifications citrate stabilized gold nanoparticles were appended onto the surface of amine modified core-shell cobalt-silica nanoparticles. Gold decorated magnetic core-shell structures were used as SERS substrate with Raman dyes
brilliant cresyl blue (BCB) and rhodamine 6G (R6G). They were also utilized for preconcentration and SERS detection of 4-mercapto benzoic acid (4-MBA). Gold nanoparticles on the silica and thiol group on the 4-MBA were very selective to each other, thus, 4-MBA could be attached on to gold surface and it could be easily separated magnetically from the reaction medium and identified by Raman spectroscopy. Characterization of the cobalt, cobalt-silica and gold modified cobalt-silica nanoparticles was done by Field Emission Scanning Electron Microscopy (FE-SEM), Scanning-Transmission Electron Microscopy (S-TEM), Energy-Dispersive X-ray Spectroscopy (EDX), UV-Vis spectrometry, and Raman microscope system.

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McNay, Graeme. "Advancing surface enhanced resonance Raman scattering (SERRS) techniques for biological detection." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438129.

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McCarney, Karen Michelle. "A flow cell surface enhanced resonance Raman scattering (SERRS) detection system." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426325.

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Nguyen, Thi Bich Ha. "Surface enhanced raman scattering (SERS) for in situ analysis of mixture of polycyclic aromatic hydrocarbons (PAHs) in sea water." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970620012.

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Mallinder, Benjamin. "Detection of deoxyribonucleic acid by surface enhanced resonance Raman scattering spectroscopy (SERRS)." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248771.

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Coria, Garcia Jose Conrado. "SURFACE ENHANCED RAMAN SCATTERING OF INTERFACIAL HALIDE IONS AND WATER AT SILVER ELECTRODES IN THE PRESENCE OF LEAD (SERS, ADSORPTION, DEPOSITION)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275414.

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Johnston, Hannah Elizabeth. "Systems redox biology analysis of cancer." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31348.

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The Warburg effect describes the survival advantage of cancer cells in that they can proliferate under low oxygen/hypoxic conditions via a less efficient pathway known as glycolysis. It has not yet been documented at which point, in an oxygen gradient, phenotypic changes occur. Measuring the intracellular redox potential (IRP) and its impact on cellular dynamics would provide greater insight into how disruption of redox homeostasis caused by changes in oxygen concentration leads to aberrant cell signalling and diseases such as cancer. Current techniques in measuring IRP include redox-sensitive fluorescent proteins such as roGFP which is glutathione-specific. Measuring the concentration of one redox couple is, however, not an accurate representation of IRP as it does not necessarily inform about the state of other redox couples. Furthermore, fluorescent biosensors can suffer from photobleaching and may interact with other oxidants. The IRP was measured, in this work, using our newly developed novel-class of surface enhanced Raman scattering nanoparticles which can quantitatively measure the redox potential of cells in vitro. A 'homemade' device was created to keep the cells under fixed pO2 whilst obtaining measurements. The IRP was correlated with the transcriptomic and downstream metabolic profiles of MCF7 breast cancer cells, under perturbed pO2, using 1H NMR spectroscopy (NMR), mass spectrometry (MS) and RNA-sequencing. Discriminatory metabolites were all associated with energy and glucose metabolism. Discriminatory microRNAs were all affiliated with the hallmarks of cancer; the regulation of some is controlled by transcription factors containing redox-sensitive motifs in their DNA binding domains. Multivariate analysis techniques were used to analyse the different data streams in a holistic way that allows the correlation of redox potential, metabolism and transcription.

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Cruz, Sandra Maria Alves da. "Nanocomposites as probes for biodetection by SERS." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14134.

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Doutoramento em Nanociências e Nanotecnologia
The present work aimed to explore the potential of new nanocomposites based on carbon nanostructures and metal nanoparticles for the detection of biomolecules through surface enhanced Raman scattering (SERS). In a first step, polyvinyl alcohol composites were prepared incorporating silver nanoparticles by two different reduction procedures. At first without introduction of carbon nanostructures. These composites showed good results for the SERS identification of nucleic acids. Next, the synthesis and characterization of graphene oxide was studied to be used in the preparation of silver and gold nanocomposites. The reduction of this nanomaterial with different chemical agents was explored, since its reduction degree may be a determinant factor for the application envisaged (biomolecules interaction). The preparation of the nanocomposites with silver and gold was performed with different reducing agents. The SERS activity of these new nanocomposites was then explored in the presence of different analytes, varying the experimental conditions for Raman spectra acquisition. It was interesting to verify that the silver containing nanocomposites presented the particularity to intensify the graphene D and G bands. It is also important to highlight that a new eco-friendly reducing agent was tested for the synthesis of the graphene oxide composites, an Eucalyptus Globulus extract. Other variable introduced was the preparation of gold nanostars synthesized with hydroxylamine in the presence of graphene oxide, which allowed the preparation of a new nanocomposite with SERS potential. Fibrous membranes were also prepared by electrospinning with the aim to prepare SERS supports with adequate topography and porosity for the formation of nanoparticles agglomerates for the creation of the so-called hot-spots and also to allow the penetration of the analyte molecules. The polymers polyvinyl alcohol and polyacrylonitrile were selected for electrospinning. Using this technique, electrospun mantles with silver and gold nanoparticles and nanocomposites were prepared. Several variables were studied, such as the introduction of the nano-fillers during the electrospinning process, later deposition of the nano-fillers on the simple electrospun polymeric fibres and surface functionalization of the simple polymeric membranes to link the nano-fillers. At last, the potentialities of using carbon nanotubes forests, produced by chemical vapor deposition and coated with gold film by sputtering, as new SERS substrates were explored. It was found that the SERS detection of DNA bases and ADN itself is possible using these substrates.
O presente trabalho pretendeu explorar as potencialidades de nanocompósitos, baseados em nanoestruturas de carbono e nanopartículas metálicas, para a deteção de biomoléculas através da técnica de difusão de Raman intensificada por superfície (SERS, surface-enhanced Raman scattering). Primeiramente foram preparados nanocompositos de álcool polivinílico com nanopartículas de prata sintetizadas através de dois métodos, ainda sem a presença de nanoestruturas de carbono. Verificou-se que estas membranas apresentaram bons resultados na identificação de ácidos nucleicos por SERS. A síntese e caracterização do óxido de grafeno que serviu de base para a preparação dos nanocompósitos de prata e ouro foi objecto de estudo. A sua redução química com diferentes agentes redutores foi explorada, uma vez que o grau de redução deste nanomaterial pode ser um fator determinante para a aplicação pretendida (interação com biomoléculas). A preparação de nanocompósitos de óxido de grafeno com prata e ouro foi realizada com diferentes agentes redutores. A atividade de SERS destes novos nanocompósitos foi então explorada na presença de vários analitos, em diferentes condições de aquisição dos espectros de Raman, bem como em diferentes tipos de suporte. Verificou-se que os nanocompósitos preparados com prata apresentaram a particularidade de permitirem a intensificação dos sinais de Raman das bandas D e G do grafeno. É de salientar a introdução de um novo agente redutor amigo do ambiente para síntese de compósitos de grafeno com nanopartículas metálicas: o extrato de eucalipto. Outra variável introduzida foi a preparação de nanopartículas de ouro em forma de nanoestrelas sintetizadas com hidroxilamina na presença de óxido de grafeno, tendo-se obtido assim um novo nanocompósito com potencialidades em SERS. Com o objectivo de preparar suportes para SERS com uma topografia e porosidade adequadas à criação de locais privilegiados para a agregação de nanopartículas metálicas e para a penetração das moléculas do analito foram produzidas mantas por electrofiação. Para tal, selecionaram-se os polímeros álcool polivinílico e poliacrilonitrilo. Com esta técnica preparam-se igualmente nanocompósitos de ouro ou prata e grafeno. Estudaram-se algumas variáveis de síntese, tais como a introdução de nanopartículas e nanocompósitos in situ, (isto é, durante o processo de electrofiação), deposição posterior das nanopartículas e dos nanocompósitos nas fibras poliméricas (preparadas previamente) e funcionalização superficial das mantas com o objectivo de ligar os nanomateriais a posteriori. Por fim, foi também explorada a potencialidade em SERS de novas estruturas compostas por florestas de nanotubos de carbono com cobertura de ouro produzidas por deposição química de vapor. Verificou-se que a detecção de bases de ADN e o próprio ADN é possível usando estes materiais.

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Kaya, Murat. "Preparation And Surface Modification Of Noble Metal Nanoparticles With Tunable Optical Properties For Sers Applications." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613129/index.pdf.

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Metal nanostructures exhibit a wide variety of interesting physical and chemical properties, which can be tailored by altering their size, morphology, composition, and environment. Gold and silver nanostructures have received considerable attention for many decades because of their widespread use in applications such as catalysis, photonics, electronics, optoelectronics, information storage, chemical and biological sensing, surface plasmon resonance and surface-enhanced Raman scattering (SERS) detection. This thesis is composed of three main parts about the synthesis, characterization and SERS applications of shape-controlled and surface modified noble metal nanoparticles. The first part is related to a simple synthesis of shape controlled solid gold, hollow gold, silver, gold-silver core-shell, hollow gold-silver double-shell nanoparticles by applying aqueous solution chemistry. Nanoparticles obtained were used for SERS detection of dye molecules like brilliant cresyl blue (BCB) and crystal violet (CV) in aqueous system. v The second part involves the synthesis of surface modified silver nanoparticles for the detection of dopamine (DA) molecules. Determination of a dopamine molecule attached to a iron-nitrilotriaceticacid modified silver (Ag-Fe(NTA)) nanoparticles by using surface-enhanced resonance Raman scattering (SERRS) was achieved. The Ag-Fe (NTA) substrate provided reproducibility and excellent sensitivity. Experimental results showed that DA was detected quickly and accurately without any pretreatment in nM levels with excellent discrimination against ascorbic acid (AA) (which was among the lowest value reported in direct SERS detection of DA). In the third part, a lanthanide series ion (Eu3+) containing silver nanoparticle was prepared for constructing a molecular recognition SERS substrate for the first time. The procedure reported herein, provides a simple way of achieving reproducible and sensitive SERS spectroscopy for organophosphates (OPP) detection. The sensing of the target species was confirmed by the appearance of an intense SERS signal of the methyl phosphonic acid (MPA), a model compound for nonvolatile organophosphate nerve agents, which bound to the surface of the Ag-Eu3+ nanostructure. The simplicity and low cost of the overall process makes this procedure a potential candidate for analytical control processes of nerve agents.

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Nardou, Éric. "Nanoparticules métalliques en matrices vitreuses pour l’amplification Raman." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10207/document.

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Les fibres optiques utilisées pour le transfert d’information présentent des pertes de signal pendant leur propagation. Ainsi, ces signaux ont besoin d’être régulièrement amplifiés. De nos jours, l’Amplification Raman, basée sur le principe de diffusion Raman stimulée, est une des techniques utilisées pour réaliser ces amplifications. Les nanoparticules de métaux nobles ont des propriétés optiques uniques provenant de l’oscillation collective des électrons lorsqu’elles interagissent avec une onde électromagnétique. Ces particules absorbent fortement le champ électromagnétique à une fréquence appelée fréquence de résonance de plasmon de surface. Ce travail de thèse concerne l’influence des nanoparticules métalliques sur l’amélioration de l’Amplification Raman. Il s’inscrit dans le cadre du projet ANR Fenoptic (2010-2012), réunissant l’entreprise Draka et plusieurs laboratoires français (ICB Dijon, CMCP Paris, LPCML Lyon), qui s’intéressent à l’intégration des nanoparticules de métaux nobles à l’intérieur des fibres optiques afin d’utiliser la résonance de plasmon de surface pour améliorer l’efficacité des amplificateurs optiques. Dans ce travail, différentes sources de nanoparticules métalliques ont été examinées (suspensions, couches, préformes de fibre optique). Les expériences ont porté sur la caractérisation (forme et position du plasmon) de nanoparticules de métaux nobles incluses en matrices vitreuses ainsi que sur des mesures de spectroscopie Raman au travers desquelles le phénomène de Diffusion Raman Exaltée de Surface (SERS) a particulièrement été étudié. Pour la première fois, nous avons mis en évidence l’exaltation du signal Raman d’une matrice vitreuse
Signals in optical fibers used for the transfer of information are attenuated due to impurities, scattering, absorption… To compensate for these losses, several techniques were developed like Erbium Doped Fiber Amplifier (EDFA). An alternative to rare earth doped fiber amplifier is Raman Amplification, which results from stimulated Raman scattering. Noble metal nanoparticles have optical properties induced by the collective oscillation of their conduction electrons when they interact with an electromagnetic wave. These particles strongly absorb the electromagnetic field at a frequency called surface Plasmon resonance frequency. This work is mainly based on effects leading to the improvement of the Raman Amplification. The ANR project Fenoptic (2010-2012), gathering Draka and several French laboratories (ICB (Dijon), CMCP (Paris), LPCML (Lyon)) is interested in the integration of noble metal nanoparticles in optical fibers using properties of the surface Plasmon resonance to improve the efficiency of optical amplifiers. In this work, different kinds of samples (suspensions, layers, optical fiber performs) with metal nanoparticles were studied. The experiments were based on the characterization (form and position of the Plasmon band) of noble metal nanoparticles in amorphous matrix and Raman spectroscopy was used to study the Surface Enhanced Raman Spectroscopy (SERS) effect. For the first time, we found the Raman signal exaltation of an amorphous matrix

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Appelblad, André. "Development of a Temperature Controlled Cell for Surface Enhanced Raman Spectroscopy for in situ Detection of Gases." Thesis, Umeå universitet, Institutionen för fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-89799.

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This work describes a master’s thesis in engineering physics at Umeå University carried out during the spring semester of 2014. In the thesis the student has constructed and tested a temperature controlled cell for cooling/heating of surface-enhanced-Raman-spectroscopy (SERS) substrates for rapid detection of volatile substances. The thesis was carried out at the Swedish Defence Research Agency (FOI) in Umeå, Sweden. A Linkam Scientific Instruments TS1500 cell was equipped with a Peltier element for cooling/heating and a thermistor temperature sensor. A control system was constructed, based on an Arduino Uno microcontroller board and a pulse-width-modulated (PWM) H-bridge motor driver to control the Peltier element using a proportional-integral (PI) control algorithm. The temperature controlled cell was able to regulate the temperature of a SERS substrate within -15 to +110 °C and maintain the temperature over prolonged periods at ±0.22 °C of the set point temperature. Gas phase of 2-chloro-2-(difluoromethoxy)-1,1,1-trifluoro-ethane (isoflurane) was flowed through the cell and SERS spectra were collected at different temperatures and concentrations. This test showed that the signal is increased when the substrate is cooled and reversibly decreased when the substrate was heated. Keywords: temperature control, Raman scattering, surface enhanced Raman spectroscopy SERS, SERS substrate, volatile substances, Peltier module, thermistor, PWM, H-bridge, PI(D) control.
Detta dokument beskriver ett examensarbete för civilingenjörsexamen i teknisk fysik vid Umeå Universitet som utförts under vårterminen 2014. I examensarbetet har en kyl-/värmecell för temperaturkontroll av substratytor för ytförstärkt ramanspektroskopi (SERS) för snabb detektion av farliga flyktiga ämnen konstruerats och testats. Arbetet utfördes vid Totalförsvarets forskningsinstitut (FOI) i Umeå, Sverige. Utgångspunkten var ett Linkam Scientific Instruments TS1500 mikroskopsteg, vilket utrustades med ett Peltierelement för kylning/värmning och en termistor för temperaturövervakning. Ett styrsystem baserat på ett Arduino Uno mikrostyrenhetskort konstruerades med ett motordrivkort (H-brygga) vilket använder pulsbreddsmodulering (PWM) för att reglera spänningen till Peltierelementet utifrån en PI-regulator. Den färdiga cellen klarade att reglera temperaturen på ett SERS-substrat i ett temperaturspann på ungefär -15 till +110 °C med en temperaturstabilitet på ±0.22 °C av måltemperaturen. Cellen testades sedan på flyktiga ämnen för att visa dess funktion. Difluorometyl-2,2,2-trifluoro-1-kloroetyleter (isofluran) i gasfas, med instrumentluft som bärargas, flödades genom cellen och SERS-spektra erhölls vid olika koncentrationer och temperaturer. Vid samtliga koncentrationer visades att lägre temperatur ger ökad signalstyrka. När ytan sedan värmdes upp sjönk signalen reversibelt tillbaka till ursprungsvärdet. Nyckelord: temperaturkontroll, ytförstärkt ramanspektroskopi, SERS, flyktiga ämnen, Peltierelement, thermistor, PWM, H-brygga, PI(D)-regulator.

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McLaughlin, Clare. "Development and evaluation of Surface Enhanced Resonance Raman Scattering (SERRS) spectroscopy for quantitative analysis." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366867.

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Dey, Priyanka. "Hybrid polymer/metal nanoparticles with surface enhanced raman tracking for potential use in nanomedicine." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/74991/1/Priyanka_Dey_Thesis.pdf.

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This project was a preliminary step towards the development of novel methods for early stage cancer diagnosis and treatment. Diagnostic imaging agents with high Raman signal enhancement were developed based on tailored assemblies of gold nanoparticles, which demonstrated potential for non-invasive detection from deep under the skin surface. Specifically designed polymers were employed to assemble gold nanoparticles into controlled morphologies including dimers, nanochains, nanoplates, globular and core-satellite nanostructures. Our findings suggest that the Raman enhancement is strongly dependent on assembly morphology and can be tuned to adapt to the requirements of the diagnostic agent.

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Andrade, Gustavo Fernandes Souza. "Adsorção molecular em metais de transição (ferro, cobalto e níquel) monitorada pela técnica de espalhamento Raman intensificado pela superfície: diferentes tipos de substratos metálicos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-24102007-134700/.

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Nesta tese de doutorado foram desenvolvidas metodologias para obter espectros Raman intensificados pela superficie de adsorbatos orgânicos em eletrodos de Fe, Co e Ni, que são metais que apresentam baixo fator de intensificação SERS. Foram desenvolvidos procedimentos de ativação eletroquímica para eletrodos puros dos três metais. Os protocolos de ativação eletroquímica foram utilizados para obter espectros SERS de piridina, 1,10-fenantrolina e 2- e 4-aminopiridina. O fator de intensificação determinado para o três metais, da ordem de 102-103 vezes, depende fortemente do modo vibracional do adsorbato. Os espectros SERS da piridina nos metais de transição, quando comparados com os cálculos de espectros vibracionais de cluster da piridina com átomos metálicos por DFT mostram que a formação do radical α-piridil com a adsorção nos metais de transição, proposta na literatura, não ocorre. Os perfis de excitação SERS calculados pelo modelo de transferência de carga da piridina apresentaram boa correlação com os dados experimentais. Os resultados SERS para a 1,10-fenantrolina mostraram que a espécie que adsorve é a molécula livre, com a espécie adsorvida semelhante ao complexo sintetizado. A dependência das intensidades relativas com o potencial nos espectros SERS é diferente da observada para os espectros Raman ressonante dos complexos da phen com metais de transição, mostrando que o estado excitado monitorado pelas duas técnicas é diferente. O monitoramento da adsorção das 2-aminopiridinas nos metais de transição permitiu sugerir a adsorção pelo anel piridínico para potenciais menos negativos e através dos nitrogênios piridínico e amínico para potenciais mais negativos em eletrodos de Co e Ni, e para o Fe adsorve apenas pelo nitrogênio piridínico. Em solução eletrolítica 0,1 mol.L-1 KCl, a 4-aminopiridina passa de fracamente ligada para um complexo de superficie semelhante ao complexo sintetizado para potenciais mais negativos. Utilizando a solução eletrolítica 0,1 mol.L-1 KI, as duas espécies são observadas para um intervalo maior de potenciais. No eletrodo de Ni, observa-se 4-aminopiridina protonada para E = -0,7 V; para potenciais mais negativos um complexo de superficie semelhante ao complexo sintetizado é observado. Os filmes eletrodepositados de Co e Ni em eletrodos de Ag ativado eletroquimicamente permitiram a obtenção de espectros SERS da py com alto fator de intensificação. Os filmes com espessuras maiores que 2 monocamadas de Co ou Ni apresentaram bandas intensas da piridina adsorvida nestes metais, sem bandas da piridina adsorvida em Ag, indicando que os filmes não apresentam pinholes, com intensidade SERS 100 vezes maior do que os metais puros. As intensidades relativas dos espectros SERS são similares à obtidas nos espectros SERS da piridina nos metais puros para filmes finos mais espessos do que 7 monocamadas. Foram construídos substratos de Au SERS-ativos com alto desempenho e reprodutibilidade por eletrodeposição sobre uma máscara de microesferas de poliestireno. Os espectros SERS da 4-mercaptopiridina adsorvida nos substratos otimizados apresentaram intensidade 2 vezes maior do que o eletrodo de Au ativado eletroquimicamente. A reprodutibilidade do sinal SERS para estes substratos foi de ± 15 %, indicando que estes substratos podem ser utilizados como sensores para sistemas de interesse analítico.
Surface-enhanced Raman spectra of organic adsorbates on Fe, Co and Ni electrodes were acquired after the development of specific methodologies described in this PhD thesis. Electrochemical activation procedures were developed for the three bare metaIs electrodes. The electrochemical activation protocols were applied for the acquisition of SERS spectra of pyridine, 1,10-phenanthroline and 2- and 4-aminopyridine on Fe, Co e Ni electrodes. The total and relative intensities changes of SERS bands with the applied potentials were explained by the charge transfer mechanism, which had a large contribution in the SERS enhancement for these metaIs. The enhancement factor determined for the three metaIs, on the 102-103 times range, strongly depends on the adsorbate\' s vibrational modes. The SERS spectra of pyridine on the transition metals and vibrational spectra calculations of pyridine with metallic atoms showed that the formation of α-pyridil in the adsorption on transition metaIs, suggested in the literature, didn\'t occur. The calculated pyridine SERS excitation profiles present reasonable correlaton with the experimental data. The SERS results for 1,10-phenanthroline showed that the free molecule was the adsorbing species. The potential dependence of the SERS relative intensities was different from those of the resonance Raman spectra of 1,10-phenanthroline complexes with transition metal ions, indicating that different excited states were probed by the two techniques. 2-aminopyridine adsorbed through the pyridinic ring at less negative potentials and through both pyridinic and aminic nitrogens at more negative potentials on Co and Ni electrodes, but for Fe electrode it adsorbed exclusively through the pyridinic nitrogen. 4-aminopyridine adsorbed perpendicularly to the electrode. In 0,1 mol.L-1 KCl electrolytic solution, 4-aminopyridine changed from weak1y bound to a surface complex similar to the synthesized complex at more negative potentials. In 0,1 mol.L-1 KI electrolytic solution, both species were observed in a larger potential interval. On the Ni electrode, protonated 4aminopyridine was observed for V = -0.7 V, and for more negative potentials a surface complex, similar to the synthesized one, was observed. The electrodeposition of ultrathin film of Co and Ni on electrochemically-activated Ag electrodes allowed obtaining SERS spectra of pyridine with high enhancement factors. The SERS spectra of py for films thickness higher than 2 monolayers of Co or Ni presented intense bands of pyridine adsorbed on these metals, and no bands of pyridine adsorbed on Ag were observed, indicanting the absence of pinholes in the films. The relative intensities of SERS spectra on the thin films were similar to those obtained for the SERS of pyridine on the bare metaIs electrodes for films thicker than 7 monolayers, but with SERS intensity 100 times higher. The SERS activity and signal strength reproducibility of Au nanostructured substrates obtained by electrodeposition on a polystyrene masking were evaluated. The SERS spectra of 4-mercaptopyridine adsorbed on optimized electrodes presented intensities 2 times greater than those of the electrochemically activated Au electrode. The SERS intensity reproducibility for these substrates was ± 15%, indicating the potential use of such substrates as sensors.

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Brown, Rachel. "The chemical modification of DNA for analysis by surface enhanced resonance Raman scattering (SERRS) spectroscopy." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21166.

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The detection of specific DNA sequences is of increasing interest due to the sequencing of the human genome. This can be achieved by the use of covalently labelled oligonucleotide probes detected by sensitive analytical techniques. Surface Enhanced Resonance Raman Scattering (SERRS) spectroscopy is one such technique that provides molecularly specific information about probes at very low concentrations. The enhancement results from adsorption of a chromophore within the probe to a roughened metal surface. Specific SERRS probes were synthesised using benzotriazole as the metal complexing agent and azo dyes as the chromophore. They were coupled to the 5' end of DNA using two strategies. Firstly, coupling was achieved via an amino linker, achieved by reaction of the activated carboxylic acid derivative of the SERRS label with DNA containing a free amine at the 5'end. Secondly, the phosphoramidite of the SERRS label was synthesised and incorporated as the final monomer during the solid phase synthesis of the DNA sequence. Preliminary spectroscopic data was obtained for the labelled oligonucleotides. Ultraviolet melting studies of a DNA sequence labelled with an azobenzotriazole dye show an increase in melting temperature (TM) of 5.42 °C over the same sequence without modification, suggesting that the label confers stability to the double helix. Initial SERRS optimisation experiments allowed the optimum sample conditions to be determined for these novel oligonucleotides. SERRS spectra have been obtained for each labelled oligonucleotide with a detection limit determined at 5x 10⁻⁸ M. A potential application of the labelled oligonucleotides was investigated resulting in the first ever preparation of a SERRS labelled nanoparticle probe. This provides the basis for a specific sequence detection technique based on SERRS.

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Prinz, Julia [Verfasser], Ilko [Akademischer Betreuer] Bald, Tim [Gutachter] Liedl, and Michael Uwe [Gutachter] Kumke. "DNA origami substrates as a versatile tool for surface-enhanced Raman scattering (SERS) / Julia Prinz ; Gutachter: Tim Liedl, Michael Uwe Kumke ; Betreuer: Ilko Bald." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218793171/34.

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47

Delhaye, Caroline. "Spectroscopie Raman et microfluidique : application à la diffusion Raman exaltée de surface." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13927/document.

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Ce mémoire porte sur la mise au point de plateforme microfluidique couplée à la microscopie Raman confocale, utilisée dans des conditions d’excitation de la diffusion Raman (diffusion Raman exaltée de surface), dans le but d’obtenir une détection de très haute sensibilité d’espèces moléculaires sous écoulement dans des canaux de dimensions micrométriques. Ce travail a pour ambition de démontrer la faisabilité d’un couplage microscopie Raman/microfluidique en vue de la caractérisation in-situ et locale, des espèces et des réactions mises en jeu dans les fluides en écoulement dans les microcanaux. Nous avons utilisé un microcanal de géométrie T, fabriqué par lithographie douce, dans lequel sont injectées, à vitesse constante, des nanoparticules métalliques d’or ou d’argent dans une des deux branches du canal et une solution de pyridine ou de péfloxacine dans l’autre branche. La laminarité et la stationnarité du processus nous ont permis de cartographier la zone de mélange et de mettre en évidence l’exaltation du signal de diffusion Raman de la pyridine et de la péfloxacine, obtenue grâce aux nanoparticules métalliques, dans cette zone d’interdiffusion. L’enregistrement successif de la bande d’absorption des nanoparticules d’argent (bande plasmon) et du signal de diffusion Raman de la péfloxacine, en écoulement dans un microcanal, nous a permis d’établir un lien entre la morphologie des nanostructures métalliques, et plus précisément l’état d’agrégation des nanoparticules d’argent, et l’exaltation du signal Raman de la péfloxacine observé. Nous avons alors modifié la géométrie du canal afin d’y introduire une solution d’électrolyte (NaCl et NaNO3) et de modifier localement la charge de surface des colloïdes d’argent en écoulement. Nous avons ainsi confirmé que la modification de l’état d’agrégation des nanoparticules d’argent, induite par l’ajout contrôlé de solutions d’électrolytes, permet d’amplifier le signal SERS de la péfloxacine et d’optimiser la détection en microfluidique. Enfin, nous avons développé une seconde approche qui consistait à mettre en place une structuration métallisée des parois d’un microcanal. Nous avons ainsi démontré que la fonctionnalisation chimique de surface via un organosilane (APTES) permettait de tapisser le canal avec des nanoparticules d’argent et d’amplifier le signal Raman des espèces en écoulement dans ce même microcanal
This thesis focuses on the development of a microfluidic platform coupled with confocal Raman microscopy, used in excitation conditions of Raman scattering (Surface enhanced Raman scattering, SERS) in order to gain in the detection sensitivity of molecular species flowing in channels of micrometer dimensions. This work aims to demonstrate the feasibility of coupling Raman microscopy / microfluidics for the in situ and local characterization of species and reactions taking place in the fluid flowing in microchannels. We used a T-shaped microchannel, made by soft lithography, in which gold or silver nanoparticles injected at constant speed, in one of the two branches of the channel and a solution of pyridine or pefloxacin in the other one. The laminar flow and the stationarity of the process allowed us to map the mixing zone and highlight the enhancement of the Raman signal of pyridine and pefloxacin, due to the metallic nanoparticles, in the interdiffusion zone. The recording of the both absorption band of the silver nanoparticles (plasmon band) and the Raman signal of pefloxacin, flowing in microchannel, allowed us to establish a link between the shape of the metallic nanostructure, and more precisely the silver nanoparticle aggregation state, and the enhancement of the Raman signal of pefloxacin observed. We then changed the channel geometry to introduce an electrolyte solution (NaCl and NaNO3) and locally modify the surface charge of the colloids. We have put in evidence that the change of the silver nanoparticle aggregation state, induced by the controlled addition of electrolyte solutions, could amplify the SERS signal of pefloxacin and thus optimizing the detection in microfluidics. At last, we established second a approach that consists in the metallic structuring of microchannel walls. This has shown that the surface chemical functionalization through organosilanes (APTES) allowed the pasting of the channel with silver nanoparticles, thus amplifying the Raman signal of the species flowing within the same microchannel

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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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Hong, Koh Yiin. "Label-free plasmonic detection using nanogratings fabricated by laser interference lithography." Thesis, Plasmonics, 2017. http://hdl.handle.net/1828/7849.

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Plasmonics techniques, such as surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS), have been widely used for chemical and biochemical sensing applications. One approach to excite surface plasmons is through the coupling of light into metallic grating nanostructures. Those grating nanostructures can be fabricated using state-of-the-art nanofabrication methods. Laser interference lithography (LIL) is one of those methods that allow the rapid fabrication of nanostructures with a high-throughput. In this thesis, LIL was combined with other microfabrication techniques, such as photolithography and template stripping, to fabricate different types of plasmonic sensors. Firstly, template stripping was applied to transfer LIL-fabricated patterns of one-dimensional nanogratings onto planar supports (e.g., glass slides and plane-cut optical fiber tips). A thin adhesive layer of epoxy resin was used to facilitate the transfer. The UV-Vis spectroscopic response of the nanogratings supported on glass slides demonstrated a strong dependency on the polarization of the incident light. The bulk refractive index sensitivities of the glass-supported nanogratings were dependent on the type of metal (Ag or Au) and the thickness of the metal film. The described methodology provided an efficient low-cost fabrication alternative to produce metallic nanostructures for plasmonic chemical sensing applications. Secondly, we demonstrated a versatile procedure (LIL either alone or combined with traditional laser photolithography) to prepare both large area (i.e. one inch2) and microarrays (μarrays) of metallic gratings structures capable of supporting SPR excitation (and SERS). The fabrication procedure was simple, high-throughput, and reproducible, with less than 5 % array-to-array variations in geometrical properties. The nanostructured gold μarrays were integrated on a chip for SERS detection of ppm-level of 8-quinolinol, an emerging water-borne pharmaceutical contaminant. Lastly, the LIL-fabricated large area nanogratings have been applied for SERS detection of the mixtures of quinolone antibiotics, enrofloxacin, an approved veterinary antibiotic, and one of its active metabolite, ciprofloxacin. The quantification of these analytes (enrofloxacin and ciprofloxacin) in aqueous mixtures were achieved by employing chemometric analysis. The limit of quantification of the method described in this work is in the ppm-level, with <10 % SERS spatial variation. Isotope-edited internal calibration method was attempted to improve the accuracy and reproducibility of the SERS methodology.
Graduate
2018-02-17

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Campbell, Mairi. "Development of a surface enhanced resonance Raman scattering (SERRS) method for the determination of 2,4,6-trinitrotoluene." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366875.

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