In der vorliegenden Dissertation werden verschiedene plasmonisch aktive Kern/Schale- Nanopartikel synthetisiert, experimentell und theoretisch charakterisiert und in analytischen Anwendungen der oberflächenverstärkten Raman-Spektroskopie (engl. surface-enhanced Raman scattering, SERS) eingesetzt. Es werden die optischen Eigenschaften von Gold/Silber-Nanoschalen mit durchstimmbaren Plasmonbanden behandelt. Motivation dafür ist die Frage nach optimalen SERS-Markern für die rote Laseranregung (λ = 632.8 nm). In SERS-Anwendungen gibt es die Möglichkeit mehrere Marker-Moleküle auf die Oberfläche der Nanopartikel aufzubringen, um so eine erhöhte Multiplexing-Kapazität zu generieren. Diese Option der gemischten Monolagen wird in der vorliegenden Arbeit untersucht. Es werden SERS-Marker-Konzepte für die rote Laseranregung basierend auf einzelnen Nanopartikeln gezeigt. Außerdem wird dargestellt, inwieweit sich durch die Anordnung von Nanopartikeln in allen drei Raumdimensionen neue SERS-Marker- Konzepte mit sehr guten plasmonischen Eigenschaften realisieren lassen. In den oben beschriebenen Kapiteln übernehmen Nanopartikel die Rolle des SERS-Substrats für den selektiven Nachweis eines bestimmten Zielmoleküls (z.B. Antigens). Neben diesen Anwendungen können Nanopartikel jedoch auch noch als SERS-Substrat für die markierungsfreie Detektion von Analytmolekülen eingesetzt werden. In dieser Dissertation wird die Herstellung, Charakterisierung und der Einsatz eines integrierten SERS-Substrats für die kombinierte Festphasensynthese und Analytik mittels plamonisch aktiver Gold/Glas-Kern/Schale-Nanopartikel auf Harz-Mikrokugeln behandelt.

Raman spectroscopy, together with multivariate statistical analyses, has proven to be a near real-time analytical technique capable of phenotyping cells, tissues and organs. This dissertation will show exclusively the application of the Raman spectroscopy phenotypic profiling method to; (i) microbial toxicity, (ii) ex-vivo organ perfusion, and (iii) subcellular location targeting. Real-time analytical methods for monitoring living biological systems will enable study of the physiological changes associated with growth, genetic manipulations, and adverse environmental conditions. Most existing analytical methods (NMR exempt), though highly accurate, must be performed off-line and most require destruction of the studied sample. These attributes make these methodologies less desirable to the study of physiological changes of cells, tissues, and organs. In this work, Raman spectroscopy has been identified and shown to be a good candidate for real-time analysis mainly because it can be performed: (i) in near real-time, (ii) non-destructively and with minimal sample preparation, (iii) through a glass barrier (i.e., can be performed in situ), and (iv) with minimal spectral interference from water. Here, Raman spectroscopy was used in combination with multivariate statistics to analyze the differing toxic effects of 4-C chain alcohols on E. coli. Good correlations were established between Raman spectra and off-line analytical techniques used to measure: (i) saturated, unsaturated, and cyclopropane fatty acids; (ii) amino acid composition of total protein; and (iii) cell membrane fluidity. Also, Raman 'fingerprint' analysis was used to discriminate among different phenotypic responses of cells. In addition, this methodology was applied to analyze perfusates of organs maintained by the VasoWave® organ perfusion system. Raman fingerprints can be used to assess organ health, and it is believed this data can be used to inform decisions such as whether or not to transplant an organ. Finally, molecular biology techniques were used to design and produce specific protein targets harboring a silver binding domain fusion, which upon release migrate to specific subcellular locations. By employing the related technique of surface-enhanced Raman scattering (SERS), which produces a highly amplified Raman signal in the presence of metallic nanoparticle substrates (e.g., silver nanoparticles), different regions of the E. coli cell structure were studied. The target regions studied by the technique included: (i) outer cell membrane, (ii) periplasm, and the (iii) cytoplasm. / Ph. D.

Nanoscience dominates almost all areas of science and technology in the 21st century. Nanoparticles are of fundamental interest since they possess unique size dependent properties (optical, electrical, mechanical, chemical, magnetic etc.), which are quite different from the bulk and the atomic state. The research work presented in the thesis is on the preparation, characterization and studies on Ir, Os and graphene oxide-based systems. Interconnected Ir and Os nanochains are prepared under environmentally friendly conditions in aqueous media and subsequently used as substrates for surface enhanced Raman scaterring studies and also as electrocatalysts for oxygen reduction and formaldehyde oxidation. Ir and IrOx nanostructures are prepared using borohydride at different temperatures. The nature of interaction of heme proteins with IrOx is studied using spectroscopic techniques. Electrochemical studies on reduced graphene oxide include sensing of biomolecules with high sensitivity and oxygen reduction reaction (ORR) in aqueous alkaline medium. rGO is also used as support for anchoring Ir nanoparticles and the catalyst is used for the oxidation of benzyl amines to corresponding imines. The thesis is divided in to seven chapters and details are given below. Chapter 1 gives an introduction about the synthetic strategies and properties of metal nanostructures. This is followed by literature survey on Ir, Os and graphene oxide-based systems relevant to the present study. Aim and scope of the present investigation is given at the end. Chapter 2 discusses the experimental procedures and characterization techniques used in the present study. Chapter 3 involves the preparation, characterization and studies on interconnected Ir nanochains. Assemblies of small sized nanoparticles forming network-like structures have attracted enormous interest and different metal nanoassemblies have been reported using different procedures. Ir3+ reduction is kinetically not a very favourable process and hence there are not many attempts to synthesize Ir-based nanostructures. Assemblies of interconnected Ir nanoparticles have been synthesized in the present studies using borohydride as reducing agent and ascorbic acid as capping agent, at high temperatures. Polyfunctional capping molecules such as ascorbic acid and vitamin P play important role for the formation of network- like Ir nanostructures. Optical properties of the networks are probed using UV-Vis spectroscopy and evolution of coupled plasmon of Ir nanochains at 418 nm (figure 1) is observed. The nanochains are used as substrates for SERS studies while the catalytic activity is followed for the reduction of nitroaromatics. Electrocatalytic activity of Ir nanochains is exemplified using oxygen reduction and formaldehyde oxidation. Ir nanochains show better electrocatalytic activities than nanoparticles as shown in figure 2. Figure 1. Time dependent UV-Vis absorption spectra of Ir nanoparticles recorded at various time intervals of (a) 5; (b) 15; (c) 30 and (d) 60 minutes of reduction of Ir3+ using borohydride and the corresponding TEM images. Figure 2. Polarization curves for oxygen reduction on (i) Ir nanochains and (ii) Ir nanoparticles in (A) 0.5 M H2SO4 and (B) 0.1 M KOH at a scan rate of 0.005 V/s. Rotation speed used is 1000 rpm. Chapter 4 discusses the preparation of Ir and IrOx using borohydride. The reaction temperature determines the product. Various physicochemical, microscopic and spectroscopic techniques have been used to understand the evolution of nanostructures. Borohydride reduces Ir3+ at high temperatures to form high surface area foams, while at 25oC, it results in an alkaline environment that helps in the hydrolysis of the Ir precursor to form IrOx nanoparticles. Porous IrOx is formed when Ir foams are annealed at high temperatures. Water oxidation has been demonstrated using IrOx nanoparticles and foams. Biocompatibility of IrOx is used to study the nature of interaction of heme proteins and the formation of bioconjugates using spectroscopic techniques. IrOx forms bioconjugates with substantial changes observed in secondary and tertiary structures of proteins. Chapter 5 explores the synthesis of interconnected ultrafine Os nanoclusters and the nanostructured materials are used as SERS substrates. Os nanochains are prepared under environmentally friendly conditions using polyfunctional molecules like ascorbic acid and vitamin P as both reducing agent and capping agent in aqueous media. Small sized (1-1.5 nm) Os nanoparticles spontaneously self-assemble to form clusters of few tens of nm that in turn self-organize to form branched nanochains of several microns in size. The as-formed nanochains show surface plasmon absorption in the visible region 540 nm which make them active substrates for surface enhanced Raman scattering (SERS) studies. High SERS activity is observed for fluorescent analyte, rhodamine 6G and non-fluorescent analyte, mercaptopyridine, with different laser excitation sources. Efficient energy transfer from fluorescent R6G dye to Os nanochains is observed based on steady state and time resolved fluorescence measurements.Figure 3. (I) Time dependent UV-Vis absorption spectra of Os nanochains recorded at different time intervals of (a) 5; (b) 7; (c) 15; (d) 30 and (e) 60 minutes. Inset shows the TEM images of Os nanochains after 60 minutes of reduction. (II) SERS spectra of 4-MPy adsorbed on Os nanochains from (a) 1 mM; (b) 10 µM and (c) 1 µM solutions using 514 nm laser excitation. Chapter 6 discusses the studies based on reduced graphene oxide. Reduced graphene oxide (rGO) is explored as electrodes for simultaneous determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at low concentrations useful in medical diagnostics (figure 4A). It is also used as metal-free electrocatalyst for ORR (figure 4B). The use of rGO as a support for anchoring Ir nanoparticles is probed and subsequently the Ir/rGO is used as catalyst for direct aerobic oxidation of benzyl amine derivatives to corresponding imines. Chapter 7 describes the summary of the work and scope for further studies. Appendix 1 discusses the preparation of different Ir nanostructures using simple galvanic displacement reaction on copper foil while appendix 2 describes the preparation of different sized Ir nanoparticles and their electrocatalytic activity towards oxygen reduction reaction

Ce travail présente une méthode originale de détection et de quantification, sans étape de marquage, de la proportion de bases libres contenues dans des acides nucléiques. La spectrométrie de diffusion Raman exaltée de surface (DRES ou SERS en anglais) nous a permis d’obtenir la signature spectrale spécifique des nucléotides caractéristiques des ARN (adénosine, cytosine, guanosine et uridine), en utilisant des colloïdes d’argent comme substrat-DRES et des ajouts de MgCl2 comme agent d’agrégation. Les conditions de détection ont été optimisées pour établir un protocole de quantification de la proportion des nucléobases non-appariées par spectrométrie DRES. Les limites de détection obtenues sont de l’ordre de quelques dizaines de picomoles. L’amélioration de la reproductibilité des mesures par spectrométrie DRES passe par le contrôle précis des temps de réaction (adsorption et agrégation), qui peut être contrôlé grâce à l’utilisation de plateformes microfluidiques adaptées. Nous avons mis en œuvre deux types de plateformes microfluidiques, l’une basée sur des écoulements monophasiques et l’autre sur la génération de gouttes. Les espèces à analyser sont contenus dans les gouttes, permettant la détection in situ par spectrométrie DRES des divers nucléotides. / This work deals with the development of an original label-free method for free bases proportions detection and quantification of nucleic acids. The surface enhanced Raman spectroscopy (SERS) allowed obtaining the specific spectral signature of characteristic nucleotides of RNA (adenosine, cytosine, guanosine and uridine), using silver colloids as SERS substrate and MgCl2 addition as aggregating agent. Then, the condition detection have optimizing to establish a label-free quantification protocol of free nucleobases proportion by SERS spectroscopy. The detection limits obtained are order of few picomoles. The reproducibility improvement of SERS detection requires the precise control of time reaction (adsorption and aggregation), which could be control thanks to microfluidic chips use. We have implemented two different microfluidic chips, one based on single-phase flows and one other based on droplets generation. The analyzed species are containing in droplets, allowing in situ detection by spectroscopy SERS of various nucleotides.

Die Charakterisierung der Protein-Nanopartikel-Wechselwirkungen in komplexen biomolekularen Systemen wie einer lebenden Zelle ist für die Pharma-, Medizin- und Umweltforschung von entscheidender Bedeutung. In solchen biomolekularen Systemen adsorbieren Proteine leicht auf der Oberfläche von Nanopartikeln, die die Proteinkorona bilden. Diese Arbeit konzentriert sich auf die Charakterisierung der Proteinkorona in lebenden Zellen, wobei verschiedene analytische Ansätze kombiniert werden. Experimente mit oberflächenverstärkter Raman-Streuung (SERS) an reinen Proteinlösungen zeigten die Konzentrationsabhängigkeit der Protein-Gold-Nanopartikel-Wechselwirkungen, die zu unterschiedlichen SERS-Spektren führten und ermöglichten die Bestimmung von Proteinsegmenten, die an Citrat-stabilisierte Gold-Nanopartikel binden. In SERS-Experimenten mit lebenden Zellen wurde die Anwesenheit von Proteinfragmenten in der innersten Schicht der Proteinkorona, die als harte Proteinkorona bezeichnet wird, festgestellt. Eine analytische Methode, die Natriumdodecylsulfat-Polyacrylamid-Gelelektrophorese und Hochleistungs-Flüssigchromatographie-gekoppelte Elektrospray-Ionisations-Massenspektrometrie kombiniert, wurde entwickelt, um die Bestandteile der Hartproteinkorona zu identifizieren. Die Proteomics-, SERS- und Cryo-Soft-X-Ray-Nanotomographiedaten, wobei letztere Informationen über die dreidimensionale Ultrastruktur der Zelle liefern, zeigen den Aufnahmemechanismus, die Verarbeitung, die Akkumulationsstelle, die molekulare Umgebung und die induzierten zellulären Reaktionen internalisierter Goldnanopartikel. Diese Arbeit validiert die Verwendung von SERS bei der Analyse der Proteinkorona in der Lösung von Modellproteinen und in lebenden Zellen und präsentiert eine geeignete Methode zur Analyse der unveränderten harten Proteinkorona, die in lebenden Zellen gebildet wird. / The characterization of the protein-nanoparticle interactions in complex biomolecular systems such as a living cell is vital for pharmaceutical, medical, and environmental research fields. In such biomolecular systems, proteins readily adsorb on the surface of nanoparticles forming the protein corona. This thesis focuses on the characterization of the protein corona in living cells combining different analytical approaches. Surface-enhanced Raman scattering (SERS) experiments on pure protein solutions revealed the concentration dependence of the protein-gold nanoparticle interactions resulting in different SERS spectra, and allowed for the determination of protein segments binding to citrate-stabilized gold nanoparticles. In live cell SERS experiments, the presence of protein fragments in the innermost layer of the protein corona, called the hard protein corona, was revealed. An analytical method combining sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography-coupled electrospray ionization mass spectrometry was developed to identify the constituents of the hard protein corona. The proteomics, SERS, and cryo soft X-ray nanotomography data, the latter providing information of the three dimensional ultrastructure of the cell, reveal the uptake mechanism, processing, accumulation site, molecular environment, and the induced cellular responses of internalized gold nanoparticles. This work validates the use of SERS in the analysis of the protein corona in the solution of model proteins and in living cells, and presents a suitable method for the analysis of the unaltered hard protein corona formed in living cells.

Im ersten Teil der Arbeit werden Signalverstärkungsmechanismen für Raman-Spektroskopie erschlossen und evaluiert. Die als geeignet bewerteten Methoden finden im zweiten Teil ihre Anwendung zur Untersuchung der vibronischen Eigenschaften von dünnen Manganphthalocyaninschichten, die anschließend mit Kalium interkaliert werden. Hierbei sind verschiedene Phasen identifizierbar, die ein ganzzahliges Verhältnis von Kaliumatomen zu Manganphthalocyaninmolekülen besitzen. Im dritten Teil werden die elektrischen Eigenschaften durch die Verwendung dieses Materialsystems als aktives Medium eines Feldeffekttransistors untersucht.

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.

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.

In dieser Arbeit werden die nichtlokalen sowie nichtlinearen Eigenschaften plasmonischer Nanopartikel behandelt, wie sie im hydrodynamischen Modell enthalten sind. Das hydrodynamische Materialmodell stellt eine Erweiterung des Drude Modells dar, in der Korrekturen in der Beschreibung des Elektronenplasmas berücksichtigt werden. Einer ausführlichen Einführung des Materialmodells folgt eine analytische Diskussion der Auswirkungen der Nichtlokalität am Beispiel eines einzelnen Zylinders. Hierbei werden die durch die Nichtlokalität herbeigeführten Frequenzverschiebungen in den Streu- und Absorptionsspektren quantifiziert und asymptotisch behandelt. Des Weiteren wird mit Hilfe einer konformen Abbildung das Problem eines zylindrischen Dimers in der Elektrostatischen Näherung gelöst und die Moden der Struktur bestimmt. Diese Untersuchungen dienen als maßgebliche Grundlage für weiterführende numerische Studien die mit der diskontinuierlichen Galerkin Zeitraummethode durchgeführt werden. Die durch die analytischen Betrachtungen gewonnene Kenntnis der Moden ermöglicht es, im Zusammenhang mit gruppentheoretischen Betrachtungen und numerischen Untersuchungen, rigorose Auswahlregeln für die Anregung der Moden durch lineare und nichtlineare Prozesse aufzustellen. In weiterführenden numerischen Simulationen werden außerdem Strukturen niedrigerer Symmetrie, auf die sich die Auswahlregeln übertragen lassen, untersucht. Zudem werden numerische Studien präsentiert in denen der Einfluss der Nichtlokalität auf Feldüberhöhungen in Dimeren und doppel-resonantes Verhalten (es liegt sowohl bei der Frequenz des eingestrahlten Lichtes als auch bei der zweiten harmonischen eine Resonanz vor) untersucht werden. / This thesis deals with the nonlocal and nonlinear properties of plasmonic nanoparticles, as described by the hydrodynamic model. The hydrodynamic material model represents an extension of the Drude model that contains corrections to the descriptions of the electron plasma. After a thorough derivation of the material model, analytical discussions of nonlocality are presented for the example of a single cylinder. The frequency shifts in the scattering and absorption spectra are quantified and treated asymptotically. Furthermore, by applying a conformal map, the problem of a cylindrical dimer is solved in the electrostatic limit and the modes of the structure are determined. These investigations lay the foundations for numerical investigations which are performed employing the discontinuous Galerkin time domain method. The analytical knowledge of the modes, in conjunction with group theoretical considerations and numerical analysis, enables the formulation of rigorous selection rules for the excitation of modes by linear and nonlinear processes. In further numerical studies, the influence of nonlocality on the field enhancement in dimer structures and double-resonant behavior (a resonance is found at the frequency of the incoming light and at the second harmonic) are investigated.

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.