Dissertations / Theses on the topic 'SERS'

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.

SERS is a useful spectroscopic technique that was discovered 30 years ago, and has recently seen a renaissance in research. Sphere segment void (SSV) substrates have been developed as reproducible, stable SERS substrates by electrodeposition of a metal through a colloidal template. The effect of adsorbing an organic monolayer on the surface of an SSV substrate was studied, which results in a slight shift in the plasmonic absorption. This was compared with the reduction of a diazonium salt on the surface, which results in a significant increase in plasmonic absorption, attributed to a physical sharpening of the metal structure, and in turn better defined plasmon modes. The Au surface was also modified with an ultra thin layer of Pt, and a comparison was made between oxidation-reduction cycled roughened (ORC) and SSV substrates with and without Pt. The SSV substrates were found to be more reproducible, and (after modification with a thin-layer of Pt), gave spectra more representative of bulk Pt substrates than ORC. Lastly the surface was functionalised with metallic nanoparticles (NPs), and a large increase in spectral intensity was observed. This was attributed to a strongly localised electric field between the NP and the substrate, which resulted in an additional enhancement of between 102-103 depending on the method of assembly used. Functionalisation of the NPs introduced the possibility of drug detection or studies in drug delivery using such a system.

The use of surface-enhanced Raman spectroscopy (SERS) as an analytical tool has gained increased interest in recent years due to its greater sensitivity and “fingerprinting” ability when compared to other spectroscopic techniques. This thesis discusses approaches used to detect aggregated and single metallic nanoparticles in a high throughput fashion using SERRS. This was accomplished by building a sensitive optical detection platform with high temporal resolution detectors. Initially, nanoparticle aggregates compartmentalized within microdroplets were detected. Each microdroplet can be considered an individual microreactor. Microdroplet flow rate was changed to characterize the effect on microdroplet throughput. Multiple full spectra acquisitions were taken within each microdroplet which was used to compare the different aggregate geometries within each droplet. In addition to segmented flow, single particles in a continuous flow environment are also detected and characterized. A flow based system significantly increases nanoparticle throughput through the probe volume reducing acquisition time. Using correlation spectroscopy, the size of the nanoparticle can be determined and the effect of flow rate on the nanoparticle flow time can be seen. As another detection strategy, single metallic nanoparticles are also detected optically as they translocate through a solid state nanopore. The high electric field generated at the nanopore electrophoretically drives the charged nanoparticles through the nanopore. The nanopore confines the particles to a single channel ensuring single particle detection. Besides the vibrational information that SERS is able to extract, coupling metallic nanoparticles with metallic nanoparticles creates an additional electromagnetic enhancement with increases the SERS signal.

This dissertation mainly focuses on applications of Surface Enhance Raman Scattering (SERS) to detect tobacco-related biomarkers with optimized experimental conditions (pH and aggregating agents) and SERS substrates (silica core and silver shell nanoparticles). Cotinine (COT) and trans 3-hydroxycotinine (3HC), metabolized from nicotine as one of main chemicals of tobacco, have been used as tobacco biomarkers because their half-life are longer than that of nicotine, which enable to monitor the tobacco exposure. The effects of aggregating agents and pH on SERS detection of COT and 3HC were investigated. Aggregating agents play an important role in SERS detection of target molecules since the strong SERS enhancements are observed from junctions of nanoparticles which can be induced by aggregating agents, and so called "hot spot". That is, the more hot spots are created among the nanoparticles by aggregating agents, the higher the SERS enhancement is. Five cationic (K+, Na+, Mg2+, Li+, Ca2+) and three anionic (Cl-, Br-, I-) aggregating agents were tested. Interestingly but not surprisingly, optimal concentrations of 11 kinds of aggregating agents for COT and 3HC detections vary dramatically within two orders of magnitude. In addition, the effect of pH conditions on SERS intensity of COT and 3HC was investigated since the protonated or deprotonated molecules induced by various ranges of pH values produces change in SERS intensity of the molecule. The highest SERS enhancement is obtained using 1.5 mM MgCl2 for COT at pH 7 and 50 mM NaBr for 3HC at pH 3. Both cations and anions strongly influence the SERS enhancement. SERS enhancement depends also significantly on the type of metallic substrates. This indicates the choice of metallic substrate is critically important to achieve strong SERS enhancement. While Ag is the most commonly used materials for SERS substrates and has been demonstrated to exhibit high enhancement. It has the disadvantage of limited selection of excited wavelengths, which prevents to apply Ag SERS substrates to biological field. Dielectric core and metallic shell structure has been theoretically studied and it has been proposed that silica core and silver shell (SiO2@Ag) nanoparticles produces higher plasmon resonance than that of silver nanoparticles and their surface plasmon are tunable by controlling shell thickness. Here, SiO2@Ag nanoparticles were successfully fabricated and their activity as substrates for surface-enhanced Raman scattering (SERS) were examined. Both the core and the shell thickness exhibit strong effect on the SERS activity. Using Rhodamin 6 G (R6G) as a probe molecule, it was observed that SERS intensities of R6G were susceptible to change in Ag shell thickness and the size of core-shell nanoparticles. The 76 nm SiO2@ 23 nm Ag shell nanoparticles shows highest SERS intensity of R6G. Moreover, 76nm SiO2@ 23 nm Ag nanoparticles have higher SERS enhancements of R6G, 4-aminothiophenol (4-ATP), and cotinine (COT) than that of both silver nanoparticles and SiO2@Ag nanoparticles of previous studies. Also, the tuneability of surface plasmon of core-shell structure is flexible by changing in the size of either core or shell. In addition, three Raman spectroscopy application in material science fields were studied: MP-11 encapsulated inside of Tb-mesoMOFs, poly(methyl methacrylate) composites of copper-4,4'-trimethylenedipyridein, and surfactant-free TiO2 surface hydroxyl groups. For the first study, the interaction between the ligands of Tb-meso MOFs and MP-11 was examined. Individual Raman bands of MP-11 and the ligands of Tb-mesoMOFs were distinguished and some of bands were shifted from the complex of MP-11@Tb-mesoMOFs. It is turned out that the interactions is involved through π•••π interactions between the heme and the conjugated triazine and benzene rings of TATB ligand. Next, Raman was used to study the interaction between poly methyl methacrylate (PMMAP) composites and copper-4,4'-trimethylenedipyridein (CU-TMDP). Copper contained in polymer materials has shown improvement performance (thermal and mechanical stability). The Raman results reveal a red-shift of vibrational peaks associated with pyridine ring of CU-TMDP when CU-TMDP is dispersed into PMMA. This interaction, a dipole-dipole interaction or London dispersion force, may produce the stability improvement of metal-containing polymer. The last application is about the effect of pH levels on the phase of TiO2 crystalline. TiO2 crystal has attractive advantage of self-cleaning property. The efficiency of self-cleaning of TiO2 is dependent on the phases (anatase, rutile, and brookite) of TiO2. Raman study revealed that the formation of the anatase phase of TiO2 is interrupted as the pH level increases.

Schnelltests sind eine weit verbreitete Analysemethode, um vor Ort schnelle analytische Aussagen treffen zu können. Ein möglicher Zugang zu Schnelltests für Analyten in geringer Konzentration könnten Messung von Oberflächenverstärkten Raman-Spektren sein. In der vorliegenden Arbeit wird insbesondere auf drei Aspekte der SERS-Messungen (= Oberflächenverstärkte Raman-Streuung) eingegangen: die Reproduzierbarkeit der SERS-Signalintensität, die Interpretation der Konzentrationskurven und die Analyse von Probengemischen. Für die Untersuchung der Reproduzierbarkeit wurden verschiedene Auftragungsmethoden und Messsysteme getestet und es wurde untersucht, wie reproduzierbar die Signalintensitäten über einen längeren Zeitraum sind. Dabei wurde festgestellt, dass die Kombination von einer homogenen Auftragung der Nanopartikelsuspensionen auf dem Papier und ein großer Durchmesser des Laser- und Detektionspunktes auf der Probe zu einer stabileren Signalintensität führen. Die bei einem Labormessaufbau eine Stabilität des Messsignals von ca. 20 % relativer Standardabweichung über einen Zeitraum von ca. 2,5 Monaten lieferte. Für die Analyse und Auswertung der Abhängigkeiten der SERS-Signalintensität von der Konzentration des Analyten wurden Konzentrationsreihen von verschiedenen Verbindungen aufgenommen. Die Messdaten konnten mit einer Langmuir-Isotherme beschrieben und mit dem Langmuir-SERS-Modell erklärt werden. Für die gemessenen Thiolverbindungen wurde zudem noch eine weitere Möglichkeit der quantitativen Analyse gefunden, die auf der Auswertung der Verschiebung von bestimmten SERS-Banden im Spektrum in Abhängigkeit von der Analytkonzentration beruht. Für die Analysen der Mehrkomponenten-Lösungen wurden die Papierbasierten Mikrofluidik-Analysesysteme (µPADs) eingesetzt. Hier konnte beobachtet werden, dass Analyten aus einer Lösung auf Grund ihrer hohen Affinität zu den Nanopartikeln abgetrennt werden können und es so möglich ist, diese zu analysieren.
Rapid tests are widely used analytical methods for obtaining analytical information immediately on site. Surface enhanced Raman scattering (SERS) is a possible detection method for compounds in diluted samples. This thesis focuses mainly on three aspects: reproducibility of SERS signal intensity, interpretation of concentration curves and analysis of sample mixtures. The signal reproducibility was investigated using different deposition methods and measurement systems and the reproducibility of measurements was tested over longer periods of time. It was found that the most stable signal intensity was obtained using a combination of homogeneous deposition of a nanoparticle suspension on paper and a detection configuration that involves large diameters of both, the laser and the detection spot on the sample. It was shown with a laboratory setup, that comparatively stable measurements are possible with a relative standard deviation of approx. 20 % over a period of approx. 2.5 months. For the analysis and interpretation of the dependence of the SERS signal intensity on the concentration of the analyte, concentration series of different compounds were measured. The measurement data could be fitted with a Langmuir isotherm and explained with the Langmuir SERS model. For the measured thiol compounds an alternative option for quantification was found: the shift of certain SERS bands in the Raman spectrum as a function of analyte concentration. For the analysis of compound mixture in solution microfluidic paper-based analytical devices (µPADs) were used. It was observed that certain analytes which have a high affinity for the nanoparticles can be separated from the solution and thereby analyzed.

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.

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.

ABSTRACT PREPARATION AND CHARACTERIZATION OF SILVER SERS NANOTAGS Kibar, Seda M.S., Department of Chemistry Supervisor: Prof. Dr. Mü
rvet Volkan December 2010, 88 pages Tags are materials used for labeling substances and so make possible the qualitative and quantitative analysis both in macroscopic and microscopic world. Nowadays, surface enhanced Raman spectroscopy became the favored one among the optical based-tag detection systems. Progress in surface enhanced Raman detection and imaging technologies depends on the availability of Raman labels with strong light scattering characteristics. In this study various SERS nanotags were prepared. An ideal SERS nanotag consists of three parts, core nanoparticle for enhancement, Raman active molecule for signature and a shell for protection and further functionalization. As a core material, silver nanoparticles were prepared using the chemical reduction method with sodium citrate as reductant. SERS enhancement provided by Ag particles prepared was examined. For colloidal stabilization and further surface modifications, silica with a controlled thickness was deposited on Ag nanoparticles. Three single-dye doped nanotags, Ag-BCB@SiO2 Ag-CFV@SiO2 and Ag-CV@SiO2 were prepared using positively charged dyes, brilliant cresyl blue (BCB), cresyl fast violet (CFV) and cresyl violet (CV). The effects of silica thickness and dye concentration in the reaction medium were examined. Stability of prepared nanotags and repeatability of the method were investigated. Multi-dye doped nanotags were prepared using BCB and CFV solutions mixed at various concentration ratios. Resulting Raman spectra Ag-BCB-CFV@SiO2 nanotags successfully exhibited characteristic peaks of each dye with a good resolution. In addition, the molar ratio between dyes BCB and CFV was reflected on the related spectra. A linear correlation was observed between the molar ratio of the dyes and their Raman intensity ratio.

Fungal species perform many important roles in biotechnology and recycling and act as agents of disease and decay. Surface-enhanced Raman scattering (SERS) has attracted significant attention as an analytical method for chemical and biological identification. For SERS experiments, it is essential to generate gold nanoparticles (AuNPs) with proper sizes and shapes. Raman and SERS imaging of fungi via in vivo synthesis of AuNPs were used to explore cellular components of Aspergillus nidulans (A. nidulans) cell. Critical parameters including pH, temperature and metal concentration affect the sizes and shapes of the NPs. For better control of NP formation (size, shape and location), pre-formed NP were incubated with A. nidulans colonies. Aspergillus nidulans outer hyphal walls were coated with NPs. Raman and SERS imaging of fungal walls revealed that proteins, carbohydrates and lipids are the main constituents of fungal cell wall.
October 2014

MicroRNAs (miRNAs) are short non-coding RNA sequences with a length of 18 to 24 nucleotides and are known to modulate protein expression by binding to complementary sequences of messenger RNA (mRNA). Despite being discovered only recently, there is growing evidence that miRNAs are involved in key biological processes. Recent studies have shown a correlation between circulating miRNA biomarkers and many diseases including type 2 diabetes. The development of a method for miRNA detection is of great importance as it could allow for early detection of type 2 diabetes, and therefore may have the potential to reduce the number of people with undiagnosed diabetes. Many methods can be used for miRNA detection, however surface enhanced Raman scattering (SERS) is an ideal candidate as it is considered to be a fast, highly sensitive and an extremely effective technique for miRNA detection when applied with bio-functionalised metallic nanoparticles. In addition, it offers the capability for the simultaneous detection of multiple targets, which provides SERS with major advantages over other techniques. The research began with the functionalization of silver nanoparticles using DNA oligonucleotide sequences and successive testing of their ability to detect miRNA biomarkers with a clinical relevance to type 2 diabetes in a solution-based assay. The silver nanoparticle conjugates were functionalised using thiol modified oligonucleotides and a Raman reporter to aid SERS detection. When the sample was exposed to a complementary strand of miRNA target, the nanoparticles aggregated and increased the SERS signal. Using a similar sandwich assay format, miRNA targets were also detected using a solid phase assay incorporating lateral flow strips. Lateral flow devices (LFDs) are already established for the detection of nucleic acids, and by using SERS, the detection sensitivity for targets in biological samples may be increased. Here we have been able to detect miRNA by direct visualisation of the lateral flow strips, and by SERS detection at very low concentrations difficult to see by the naked eye. These two approaches, towards using SERS for miRNA detection, are very promising and could allow biologists and clinicians to measure and monitor miRNA levels, for use in medical diagnosis and early detection of many diseases, not just type 2 diabetes.

Redox regulation and homeostasis are critically important in the regulation of cell function; however, there are significant challenges in quantitatively measuring and monitoring intracellular redox potentials. The work in this thesis details a novel approach to intracellular redox monitoring. The approach is based on the use of nanosensors, which comprise molecules capable of sensing the local redox potential, assembled on gold nanoshells. Since the Raman spectra of the sensor molecules change depending on their oxidation state, and since the nanoshells allow a large enhancement of the Raman scattering, intracellular potential can be calculated by simple optical measurements. A full description of the design, fabrication and characterisation (spectroscopic and electrochemical) of the nanosensors is provided within. The ability to deliver nanosensors into cells in a controllable fashion was confirmed using electron microscopy. Results from a range of assays are also presented which reveal that introduction of nanosensors does not result in any cytotoxicity. Sensor utility in monitoring redox potentials as cells responded to physiological and superphysiological oxidative and reductive stimuli was investigated. Importantly, the capability of the nanosensors in monitoring intracellular potentials in a reversible, non-invasive manner, and over a previously unattainable potential range, is demonstrated.

This thesis explores the practical usefulness of surface enhanced Raman spectroscopy on a colloidal substrate for quantification of organic analytes in a water matrix. The method evaluated is very simple and accessible as it utilizes a commercially available hand held Raman spectrometer and citrate reduced silver colloid substrate. Spectra of 4-mercaptopyridine (Mpy) and riboflavin (Rf) samples in distilled water were recorded. A Raman enhancement factor on the order of 108 was achieved for Mpy and its limit of detection was 0.1 nM. The standard deviation of Mpy intensity was <10% for 25 nM samples recorded at the same point in time, but significantly higher for samples recorded at different times. Mpy and Rf could be detected in parallel and both analytes had a close to linear Raman intensity to concentration relationship over a 100 times relative concentration change. We conclude that with improved substrate stability, a similar method should be practically applicable for quantification of suitable analytes down to the nM-range in samples of well defined composition. Considering the method's simplicity and the limited optimization efforts it has a large room for improvement.

Etude par diffusion Raman exaltée de surface (SERS) de l'influence de différents dépôts d'atomes (Pd, Al, Au, Cu et Si) de l'adsorption d'éthylène, d'oxygène et de pyridine sur des couches continues ou discontinues d'argent ou sur des couches minces d'Ag déposées sur des surfaces non actives vis-à-vis de la diffusion Raman. Analyse et compréhension de l'effet SERS et en particulier de la contribution à très courte portée. Application possible de la spectroscopie Raman à l'étude des surfaces.

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.

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×.

TESIS DE LICENCIATURA
Nanotechnology as a field of great relevance at present has focused its efforts in the controlled obtaining of nanosystems of different shape, size, dispersion and chemical composition, as well as its different applications; Furthermore, the field of nanobiotechnology investigates the use of a biological material to manufacture nanosystems, which can improve the biocompatibility of the nanomaterial, which generates widely dispersed systems in size and morphology. For this reason, in the present research, the synthesis and characterization of three different nanosystems are presented: obtaining of silver and gold nanoparticles using Anemopsis californica extract as a reducing and stabilizing agent; generation of nanocomposites of biosynthesized graphene oxide functionalized with silver and gold nanoparticles; and obtaining of hybrid nano/microstructures of silver and gold nanoparticles using pollen grains of Dimorphotheca ecklonis as a template. In addition to the synthesis and characterization of the nanosystems, its evaluation was carried out as substrates for surface enhanced Raman spectroscopy (SERS) effect, occupying methylene blue as the signal molecule. Gold and silver nanoparticles with A. californica extract were obtained, using different solvents in the preparation of the extract (water, methanol and isopropanol), which shows significant differences in morphology depending on the type of metal of the nanoparticles and dependent of the kind of solvent used, likewise considering only hemispheric nanoparticles, significant differences were found depending on the solvent occupied for the preparation of the extract. The second system, graphene oxide synthesis is obtained by graphite exfoliation in an aqueous/surfactant system supported by A. californica extract, which adds functional groups to the 2D material surface, inducing the possibility of functionalization. Such material was functionalized by the biosynthesis of silver and gold nanoparticles, which adhered to the surface of the material, thus generating AgNPs/GO and AuNPs/GO nanocomposites. The third nanosystem evaluates the obtaining of hybrid nano/microstructures, in which pollen grains of Dimorphotheca ecklonis are used as a reducing and stabilizing agent in the synthesis of silver and gold nanoparticles, working at the same time as a biteplate for the adhesion of these, thus generating the hybrid nano/microstructures AgNPs/PG and AuNPs/PG. Finally, we report the evaluation of all the systems as substrates for the application in SERS, occupying methylene blue as a signal molecule. In the same way all the systems exhibited such property of application of the Raman signal, with special preference silver nanostructures, due to the predominant anisotropic morphology; the AuNPs/OG nanocomposites associated with the conglomeration of the particles and the properties of the template, and the nano/microstructures AgNPs/GP due to the agglomeration of the particles and the morphology of the template.
CONACYT

Nanociências e Nanotecnologia
Esta tese descreve diversas estratégias preparativas assim como estudos de caracterização de nanocompósitos e outras nanoestruturas, para a análise em espectroscopia de Raman com intensificação por superfície (SERS). Em particular foi estudada a incorporação de nanopartículas (NPs) metálicas de Ag e Au em matrizes poliméricas visando avaliar o potencial destes materiais como novos substratos para SERS na deteção de moléculas. O primeiro capítulo consiste numa revisão bibliográfica, onde é destacado o desenvolvimento de novos substratos para SERS utilizando nomeadamente nanopartículas de Ag, Au e Cu. Numa primeira fase, esta secção apresenta uma breve descrição sobre as propriedades plasmónicas dos metais utilizados e alguns conceitos básicos de espectroscopia de difusão de Raman. Posteriormente, descreve-se em mais detalhe o efeito de SERS, revendo-se sobretudo a química de materiais descrita em trabalhos recentes tendo em conta a sua utilização como novas plataformas para análise química por SERS. O capítulo 2 descreve a síntese e caracterização de nanocompósitos de poli(acrilato de butilo) obtidos através de polimerização in situ por miniemulsão na presença de nanopartículas de Ag. Os nanocompósitos Ag/PtBA foram investigados como novos substratos de SERS visando o desenvolvimento de novas plataformas versáteis para deteção molecular. Estudos como o efeito da temperatura, pH e pressão foram investigados, visando a compreensão do efeito da matriz polimérica na difusão/adsorção do analito (ácido tiossalicílico) na superfície metálica. No capítulo 3, os nanocompósitos de Ag/PtBA descritos anteriormente foram investigados detalhadamente como substratos para bio-deteção em SERS, usando a adenina como analito modelo. Os nanocompósitos foram submetidos a vários tratamentos pré-analíticos para a bio-deteção da adenina. Foram realizadas experiências nos sistemas Ag/PtBA de modo a obter informação sobre o efeito do pH na deteção deste analito em soluções aquosas diluídas. Os nanocompósitos poliméricos obtidos apresentam a vantagem de poderem ser processados utilizando tecnologia disponível. Pelo que o estudo das suas propriedades térmicas é especialmente relevante. Assim, a influência da incorporação de NPs inorgânicas na temperatura de transição vítrea (Tg) do polímero PtBA foi investigada por meio de calorimetria diferencial de varrimento (DSC) e os resultados são apresentados no capítulo 4. Estes estudos descrevem efeitos na Tg do PtBA quando analisado em nanocompósitos obtidos por diferentes métodos (métodos ex situ e in situ), contendo nanopartículas metálicas com diferentes distribuições de tamanho e presentes em quantidade variável na matriz polimérica. Estes estudos possibilitaram relacionar a influência das NPs metálicas na mobilidade das cadeias poliméricas com as propriedades térmicas observadas. O capítulo 5 descreve a preparação e caracterização de materiais compósitos de base polimérica (PtBA) e NPs de Au com morfologia de bastonetes (NRs). Estes materiais foram investigados como substratos para SERS tendo originado um bom sinal de SERS na análise de 2-2’-ditiodipiridina. Investigouse igualmente o efeito da variação da morfologia das NPs metálicas (esferas e bastonetes), a razão de aspecto (R.A.) dos bastonetes e o tipo de matriz polimérica (PtBA e PnBA) no sinal de SERS. No capítulo 6 é descrita a utilização da técnica de SERS como método alternativo para a monitorização de alterações morfológicas de coloides de NRs de Au. Os NRs de Au foram recolhidos em diferentes fases de oxidação promovida pela presença de K2S2O8 e a sua sensibilidade como substratos de SERS foi avaliada utilizando o anião dietilditiocarbamato (DTC) como analito modelo. Os estudos foram realizados utilizando as linhas de excitação a 1064 nm e 633 nm. Este estudo demonstrou que a sensibilidade dos NRs de Au como substratos de SERS diminui à medida que a sua R.A. diminui devido à competitividade do CTAB (estabilizante) e o DTC pela superfície dos NRs. É de salientar que este processo é acompanhado por um diferente comportamento em termos de adsorção dos dois tautómeros do DTC à superfície do metal. O capítulo 7 introduz um novo tipo de compósitos para SERS, utilizando matrizes biopoliméricas. Assim, descreve-se a preparação e caracterização de nanocompósitos de carragenano e NPs de Ag. Nesta secção é avaliada a utilização destes materiais como novos substratos para a análise em SERS, utilizando a 2-2’-ditiodipiridina como molécula modelo. Descrevem-se estudos pioneiros que procuram relacionar a dependência do sinal de SERS com a força do gel. Para tal, realizou-se um estudo sistemático aos nanobiocompósitos usados como substratos de SERS em diferentes condições analíticas e investigaram-se as suas propriedades reológicas. No capitulo 8 é descrita a investigação de nanocompósitos de Ag/Gelatina como substratos para SERS, utilizando o anião dietilditiocarbamato como analito modelo. Realizaram-se várias experiências para correlacionar a variação da força do gel com o aumento do sinal de SERS bem como a diferente adsorção dos dois tautómeros do DTC à superfície do metal. Ao longo desta dissertação são apresentados metodologias distintas para a preparação e obtenção de nanocompósitos com base em polímeros (sintéticos ou naturais) e NPs metálicas (Ag e Au). Esta investigação não só permitiu a síntese e estudo de novos substratos para SERS mas também a compreensão do efeito matriz/NPs metálicas no sinal de SERS e na formação de “hot spots”. Este trabalho contribui para o enriquecimento na área da Nanociência e Nanotecnologia demonstrando a eficácia e reprodutibilidade de nanocompósitos com base em polímeros como novos substratos para SERS. Embora as propriedades óticas apresentadas por estes materiais serem aqui direcionadas para a deteção molecular pela técnica de SERS, estes materiais podem ser investigados em outras área tecnológicas.
This thesis describes several strategies as well as characterization of nanocomposites and other nanostructures, for analysis in surface enhanced Raman scattering (SERS). In particular, we studied the incorporation of metal nanoparticles (NPs) such as Ag and Au in polymer matrices to assess the potential of these materials as novel SERS substrates for the detection of molecules. The first chapter consists of a literature review, which emphasized the development of new substrates for SERS using nanoparticles, including Ag, Au and Cu. Firstly; this section presents a brief description of the plasmonic properties of the metals used and some basic concepts of Raman spectroscopy. Posteriorly, the SERS effect is described in more detail, mainly reviewing the materials chemistry described in recent studies in view of their use as new platforms for chemical analysis by SERS. Chapter 2 describes the synthesis and characterization of nanocomposites of poly(butylacrylate) obtained from in situ miniemulsion polymerization in the presence of Ag nanoparticles. Nanocomposites Ag/PtBA were investigated as novel SERS substrates for the development of new versatile platforms for molecular detection. Several studies such as the effect of temperature, pH and pressure were investigated in order to understand the effect of the polymer matrix on the diffusion and adsorption of the analyte (thiosalicylic acid) on the metal surface. In chapter 3, the nanocomposite Ag/PtBA described in Chapter 2 has been investigated in more detail as potential substrates for bio-detection in SERS. These substrates were exposed to various pre-treatment methods for the detection of adenine, a base deoxyribonucleic acid (DNA). A series of experiments were carried out in the Ag/PtBA systems in order to obtain information on the effect of pH variation in the detection of the analyte in dilute aqueous solutions. The obtained polymer nanocomposites have the advantage that they can be processed, using available technology. Thus, the study of their thermal properties is especially relevant. The influence of the incorporation of inorganic NPs in the glass transition temperature (Tg) of the polymer PtBA was investigated by differential scanning calorimetry (DSC) and the results are presented in Chapter 4. These studies describe the effect on the Tg of the PtBA when nanocomposites prepared by different methods (methods in situ and ex situ), containing metal nanoparticles with different size distributions and variable amounts in the polymer matrix are analysed. These studies correlate the influence of the metal NPs in the mobility of the polymer chains with the thermal properties observed. Chapter 5 describes the preparation and characterization of polymer-based composite materials (PtBA) and Au NPs with rod morphology (NRs). These materials were investigated as substrates for SERS, lending to a good SERS signal for 2-2'-dithiodipyridine. The effect of the morphology of the metallic NPs (rods and spheres), the aspect ratio (A.R.) of the rods and the type of polymeric matrix (PtBA and PnBA) on the SERS signal was also investigated. Chapter 6 describes the use of the SERS technique as an alternative method to monitor morphological changes in colloidal Au NRs. The Au NRs were collected at different stages of oxidation promoted by the presence of K2S2O8 and their sensitivity as SERS substrates was evaluated, using the anion diethyldithiocarbamate (DTC) as molecular probe. The studies were performed using excitation lines at 1064 nm and 633 nm. This study demonstrated that the sensitivity of the Au NRs as SERS substrates decreases as their A.R. decreases due to the competitiveness of CTAB (stabilizer) and DTC for the surface of NRs. It is noted that this process is accompanied by a different behaviour in terms of adsorption of the two tautomers of the DTC to the metal surface. Chapter 7 introduces a new type of composite SERS, using biopolymer matrices. Thus, it describes the preparation and characterization of nanocomposites based on carrageenan and Ag NPs. This section evaluates the use of these materials as novel substrates for SERS analysis, using 2-2'- dithiodipyridine as molecular probe. Pioneering studies correlating the dependence of the SERS signal with the gel strength is describe in more detail. Thus, systematic studies were performed on these nanobiocomposites used as SERS substrates in different analytical conditions and their rheological properties investigated. Chapter 8 described the investigation of Ag/gelatine nanocomposites as substrates for SERS, using the diethyldithiocarbamate anion as model analyte. Several experiments were carried out to correlate the variation of the gel strength with the increase of the SERS signal as well as adsorption of the two different tautomers of the DTC on the metal surface. Throughout this work are presented different methods for preparing and obtaining polymer-based nanocomposites (natural or synthetic) and metal NPs (Ag and Au). This research has not only enabled the synthesis and study of new substrates for SERS but also the understanding of matrix/metal NPs effects in the SERS signal and the formation of "hot spots". This work contributes to the enrichment in the area of Nanoscience and Nanotechnology, demonstrating the effectiveness and reproducibility of these polymer-based nanocomposites as new SERS substrates. Although the optical properties of these materials presented here are focussed on the molecular detection by SERS, these materials can be investigated in other technological area.

Endogenous biological processes including cellular recognition, motility and differentiation together with infection often result from carbohydrate-based interactions. Investigation into glycobiological interactions using sugar-coated nanoparticles are the basis for the research described herein. Metallic nanoparticles were coated with a variety of thiol-based linker molecules. Heterobifunctional PEG (carboxyl/thiol) molecules were found to be most successful in preventing non-specific aggregation. The carboxylic acid functionality of the PEG molecules used allowed for subsequent coupling of a variety of carbohydrates to the nanoparticle surface. This resulted in the production of glyconanoparticles with unique surface functionality, for example, glucose or galactose. Additionally, functionalising the particles with Raman reporter molecules (RRMs) resulted in the measurement of surface enhanced Raman scattering (SERS) signals. Aggregation of the glyconanoparticles in the presence of a variety of carbohydrate-binding proteins (lectins) was measured via changes in the extinction profile, size and the SERS response of those particles. Nanoparticle aggregation was used for the sensitive detection of plant lectins, including the Concanavalin A and Jacalin lectin and also bacterial lectins including cholera toxin B subunit (CTB). CTB was detected sensitively, selectively and rapidly by using glyconanoparticles coated in a mixture of different carbohydrates (mixed-monolayers of galactose and N-acetylneuraminic acid). Detection was possible in both buffer and synthetic freshwater conditions, demonstrating the use of these glyconanoparticles in detecting a target in complex samples. By exploiting the reversible nature of carbohydrate-lectin interactions, it was possible to use the glyconanoparticles together with the lectin ConA to develop a glucose sensor. This performed effectively across the physiological range and into the hypo/hyperglycaemic regions in buffer conditions. Finally, the glyconanoparticles were used for the detection of plant and bacterial lectins on glass substrates by initially developing a sandwich SERS assay with a view to eventually creating SERS-based carbohydrate microarrays.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Filmes finos metálicos nanoestruturados têm despertado considerável interesse devido à sua ca- pacidade de produzir Ressonância de Plasmons de Superfície (SPR), tornando-os versáteis para aplicação em espectroscopia Raman Intensificada por Superfície (SERS). Os metais usados, geralmente, são prata, ouro, cobre e níquel uma vez que a SPR desses metais estão localizados na região do visível. Neste trabalho, foi sintetizado e caracterizado um material híbrido, consti- tuído de nanopartículas de prata ou cobre autossuportadas sobre um substrato vítreo ativo à base de fosfato, para aplicação na espectroscopia SERS. Os precursores das nanoestruturas de prata ou cobre foram introduzidos como íon na composição do vidro (NaH 2 PO 4 -H 3 BO 3 -Al 2 O 3 ), na forma de AgNO 3 ou Cu 2 O, respectivamente. O tamanho e a forma das nanopartículas formadas possuem dependência com a temperatura e o tempo de tratamento térmico. Para verificação da sensibilidade dos substratos vítreos à umidade, medidas de absorção de água foram realizadas em função de várias concentrações de Al 2 O 3 . Os resultados mostraram que os substratos vítreos SERS ativos sintetizados com 15% de Al 2 O 3 não absorvem água e as nanopartículas não são removidas em solução. Usando a molécula cresil-violeta (CV) como molécula teste, foi pos- sível obter uma amplificação da ordem de 10 5 para os substratos vítreos borofosfatos dopado com íons Ag + . Os substratos dopados com íons de cobre foram avaliados quanto a atividade SERS, usando como molécula teste a rodamina B (RB). Estes substratos vítreos SERS ativos exibiram fatores de amplificação SERS (EF) de 10 7 e 10 8 , para as linhas de laser 514,5 nm e 632,8 nm, respectivamente, com uma excelente reprodutibilidade. A rugosidade da superfície dos substratos vítreos com as nanoestruturas de cobre aumenta com o tempo de tratamento tér- mico. A intensidade SERS apresenta a mesma tendência, atingindo um máximo de amplificação para a amostra tratada durante 20 minutos. Para o tratamento durante 30 minutos, nota-se uma diminuição na intensidade. Os processos cinéticos de difusão e adsorção, responsáveis pela formação de auto-arranjos de nanoestruturas de cobre (mounds) sobre superfície dos vidros borofosfatos, foram estudados usando o método Monte Carlo Cinético, implementando uma barreira cinética que aparece quando a partícula executa uma difusão intercamada no modelo Wolf-Villain (WV). Este modelo foi capaz de reproduzir o comportamento da rugosidade em função do tempo de tratamento térmico obtido experimentalmente, medido através do expoente de crescimento β e do expoente dinâmico z.
Nanostructured thin metallic films have attracted considerable interest due to its ability to pro- duce surface plasmon resonance (SPR), making them versatile for surface-enhanced Raman spectroscopy (SERS) applications. A variety of metals are commonly used include silver, gold, copper and nickel since the SPR these metals are located in the visible region. In this work, we were synthesized and characterized a hybrid material, composed of silver or copper nanopar- ticles auto supported onto phosphate based active glass substrate, which are suitable to SERS spectroscopy. The precursors of the silver or copper nanostructures were introduced as ions in the glass composition (NaH 2 PO 4 -H 3 BO 3 -Al 2 O 3 ) as AgNO 3 or Cu 2 O, respectively. The size and shape of the formed nanoparticles have a dependence with the temperature and time of thermal treatment. For check the humidity sensitive of the vitreous substrates, water absorption mea- surements were performed as a function of several Al 2 O 3 concentrations. The results showed that the vitreous substrates SERS active synthesized with 15% Al 2 O 3 do not absorb water and the nanoparticles are not removed in water solution. Using the cresyl violet molecule (CV) in ethanol as the model molecule, was possible to obtain an SERS amplification of 10 5 for vitreous borophosphates substrates doped with silver ions. The substrates doped with copper ions were evaluated for SERS activity, using the rhodamine B (RB) as the model molecule. These vitreous SERS active substrates exhibited SERS enhancement factor (EF) of 10 7 and 10 8 , for laser lines 514,5 nm and 632,8 nm, respectively, with an excellent reproducibility. The surface roughness of the vitreous substrates with copper nanostructures increases with the thermal treatment time. The SERS intensity shows the same tendency, reaching a maximum amplification to the sample treated for 20 minutes. For annealing during 30 minutes, a decrease in intensity is noted. The kinetic processes of diffusion and adsorption, responsible for the formation of copper nanos- tructures self-arrangements (mounds) on the surface of borophosphatos glasses, were studied using the Kinetic Monte Carlo method, implementing a kinetic barrier that appears when the particle performs an interlayer diffusion in Wolf-Villain model (WV). This model was capable of reproduce the behavior of the roughness as a function of the thermal treatment time obtained experimentally, measured by growth exponent β and dynamic exponent z.

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.

Adoption of a multi-marker nanotag approach will led to better disease characterisation whilst simultaneously enabling targeting of multiple disease markers or organelles. The employed nanotag method controllably aggregated nanoparticles with 1,6-hexamethylene diamine (1,6-HMD), before polymer coating with polyvinylpyrrolidone (PVP) and labelling with small molecule reporters; 4-mercaptopyridine (MPY), 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), 4-nitrobenzenethiol (NBT) and 2-naphthalenethiol (2-NPT). Within a multiple component suspension reporters were identified by their unique peak and when present within single cells or populations they were additionally identified using component direct classical least squares (DCLS). Within a single cell three of the four components (MPY, DTNB and NBT) were positively identified. 2D SERS imaging can monitor nanotag uptake but it provides no conclusive evidence of cellular inclusion. The simultaneous determination of cellular uptake and nanotag identification was however achieved using combined 3D Raman and SERS imaging. Three of the four components were detected within a single cell and by combining 2D sections from the 3D images it was possible to determine their intracellular location. Determination of intracellular localisation was achieved using principal component analysis (PCA) since it resulted in the resolution of a subcellular compartment. However, the ultimate success of the system will only be realised when active targeting is demonstrated. Nanotags were functionalised with peptide sequences specific for the endoplasmic reticulum (ER) and trans-Golgi network (TGN). Both nanotag systems were found to locate within lipid rich regions of the cell but they could not be positively confirmed as the ER or TGN. To identify these structures and confirm localisation, further chemometric methods must be investigated including hierarchical cluster analysis (HCA). In conclusion, the SERS nanotags were suitable imaging agents for 2 and 3D cell interrogation. 3D imaging simultaneously permitted organelle resolution and the intracellular localisation of the SERS nanotags. Targeting systems were developed and in future work their localisation within organelles will be confirmed by the application of advanced chemometric methods.

Intracellular redox potential is a delicately balanced property in cells. It plays an important role in the regulation of cellular processes and dysfunction of the redox state is believed to get involved in initiation of many kinds of diseases. However, lack of suitable techniques for quantitatively monitoring the redox potential in cells with a wide range is a significant challenge. My project aims to develop SERS nanosensors for measuring intracellular redox state quantitatively and applying them to quantify hypoxia, which is generally described by the cell having a reducing environment and defined as a form of “reductive stress”. Four redox active probe molecules have been synthesised and characterised. Their Raman spectra all change as a function of local redox potential. Since these probe molecules can be assembled on gold nanoshells which are able to enhance the Raman Effect significantly, we can calculate the redox potential from simple optical SERS measurements. Transmission Electron Microscopy was used to investigate the cellular delivery of nanosensors. TEM images confirmed that either single nanosensor or small aggregates can be taken up controllably by cells and translocated in the cytoplasm. The introduction of nanosensors was also found not to be toxic to the cells. The nanosensor has been used to monitor the redox potential in resting cells as well as the redox changes when cells responded to pharmacologically induced hypoxia and oxidative stress. These measurements demonstrated that the SERS based nanosensor developed is able to monitor the intracellular redox change in a reversible, noninvasive way and respond to cellular hypoxia quantitatively.

Dans cette thèse, la définition du SERS en tant que biocapteur a été testée et une nouvelle approche a été développée. Ainsi, concernant la quantification, il est montré que le SERS peut-être un outil très efficace. Concernant la sélectivité, la qualité spectrale a été améliorée. Une excellente limite de détection associée à l’approche statistique et dynamique permet une très bonne sensibilité (inférieure au nanomolaire). Cette approche permet également une grande reproductibilité du capteur dans le temps. Ainsi, alors que le SERS ne réponds pas forcément bien aux caractéristiques d’un capteur dans son approche classique, dans notre cas le couplage entre un substrat de nanoparticules d’or non fonctionnalisées associé à un système microfluidique, le tout monté sur un microscope confocal pour des études temporelles dynamiques analysées statistiquement a contribué à définir le SERS comme un biocapteur efficace
In this thesis, the definition of SERS as a biosensor has been tested and a new approach developed for. Also, in terms of quantification, it has been shown that SERS can be an efficient tool. Concerning the selectivity, the spectral quality was improved. A low limit of detection associated to the statistical and dynamic approach allows a very good sensitivity (under the nanomolar). This approach also enables a high reproducibility in time of the sensor. Thus, as low as SERS does not well answer to the sensor capabilities in a classical approach, in our case the coupling between a non-functionalized GNPs substrate coupled with a microfluidic chip, all mounted on a confocal microscope for temporal dynamic studies statistically analyzed has contributed to define SERS as an efficient biosensor

La pollution des eaux par des composés organiques constitue un problème mondial majeur. Parmi cescomposés, les molécules aromatiques de faibles masses molaires constituent une famille largementrependue dont la toxicité et la cancérogénicité est avérée et bien documentée. La Directive-CadreEuropéenne sur l’eau (2000/60/EC, 2006/118/EC and 2006/11/EC) établit des normes de qualitéenvironnementales ayant pour objectif d’améliorer la qualité des eaux. Dans ce contexte, ledéveloppement d’outils analytiques robustes, permettant de détecter et de quantifier précisément et insitula présence de polluants dans les eaux est d’une importante primordiale. L’objectif principal de cetteétude est l’élaboration de nanocapteurs sensibles, robustes et réutilisables, permettant l’analyse depolluants organiques dans les eaux grâce à la Spectroscopie Raman Exaltée de Surface (SERS).Tout d’abord, une attention particulière a été portée à la sélection des récepteurs et des différentesstratégies de fonctionnalisation permettant d’élaborer un nanocapteur SERS capable de pré-concentrerles polluants visés. L’utilisation d’antigènes et de fragments d’antigènes (F(ab)2) a montré des résultatsprometteurs pour l’élaboration de nanocapteurs très sélectifs. Une seconde approche basée surl’utilisation de cavitants ou molécules hôtes, telles que les cyclodextrines (CDs), a été développée. Lapré-concentration sélective des polluants grâce à leur taille a été démontrée par spectroscopie Raman etSERS. Enfin, grâce à la possibilité d’identification moléculaire en milieu complexe offerte par laspectroscopie SERS, une approche permettant une pré-concentration non spécifique des polluants a étédéveloppée. Pour ce faire, différents sels de diazoniums (DSs) ont été synthétisés et greffés à la surfacedes nanocapteurs afin de créer une couche hydrophobe permettant la pré-concentration et la détection decomposés apolaires. Les performances de ces nano-capteurs ont été démontrées pour la détection de plusieurs PAHs apolaires
Environmental water pollution by organic compounds is in continues worldwide concern. Low molecular mass aromatic molecules consisting in benzene rings have received considerable attention due to a documented significant toxicity and carcinogenicity. Within the objectives of the European Water Framework Directives (2000/60/EC, 2006/118/EC and 2006/11/EC) aiming in water quality improvement, the development of analytical tools allowing in-situ accurate and sensitive detection is of primary importance and would be a meaningful innovation. With this regard, the main scope of this study was to design sensitive, reproducible, specific and reusable nanosensor for the detection of organic pollutants in environmental waters using Surface Enhanced Raman Spectroscopy (SERS).During this study the main attention was paid to the selection of suitable receptors and strategies for SERS nanosensor surface functionalisation in order to preconcentrate targeted pollutants. The application of antibodies and antigen binding fragments (F(ab)2) for surface decoration was found to be promising approach for highly selective nanosensor design. Another strategy exploited during this study was related with an application of cyclodextrins (CDs). Using Raman and SERS spectroscopies the size selective encapsulation of analytes was demonstrated. Finally, taking advantage of molecular identification in the complex environments offered by SERS technique, nanosensors providing non-specific molecular pre-concentration was considered. For this purpose several diazonium salts (DSs) were studied and applied to the surface functionalisation to create highly hydrophobic coating layer. The performance of such nanosensor was evaluated by detection of aromatic pollutants

O estudo de nanopartículas plasmônicas de ouro sob o ponto de vista conceitual foi o foco desta tese, explorando principalmente os efeitos do envoltório molecular e a intensificação dos espectros SERS tendo em vista aplicações em sensoriamento químico. Como moléculas sonda, foram selecionadas espécies multifuncionais, como a 2,4,6-trimercapto-1,3,5-triazina (TMT), 4,5-diamino-2,6- dimercaptopirimidina (DadMcP ou Dad) e a mercaptoetilpirazina (PZT), que apresentam grupos tióis capazes de ancorar nas nanopartículas de ouro, deixando outros sítios livres para interagir com substratos e complexos metálicos. Observou-se que o envoltório molecular formado no método de Turkevich, é bastante dependente das condições de síntese, tendo sido possível detectar a presença do intermediário da reação de oxidação do citrato na superfície das nanopartículas, sob condições controladas, influenciando drasticamente o comportamento SERS. Foi feito um estudo sistemático da molécula sonda 2,4,6-trimercapto-1,3,5-triazina ancorada nas nanopartículas de ouro, tanto por troca da camada passivante (citrato), como por síntese in situ com e sem agente redutor. Esses sistemas foram investigados, sob diferentes condições, como sensores SERS para metais. Esse estudo foi ampliado para a molécula sonda 4,5-diamino-2,6-dimercaptopirimidina (DadMcP), explorando a influência do tempo na coordenação dessa espécie na superfície e o efeito de diferentes eletrólitos nos processos de agregação. Finalmente, foram apresentadas fortes evidências da ocorrência de processos fotoinduzidos envolvendo as nanopartículas funcionalizadas, com destaque para a mercaptoetilpirazina (PZT), cujo comportamento mostrou-se bastante inusitado, gerando filmes fotoagregados sob influência da luz UV com possível aplicação em fotolitografia.
The study of plasmonic gold nanoparticles under the conceptual point of view was the focus of this thesis, exploring mainly, the effects of molecular shell and the intensification of SERS spectra aiming at applications in chemical sensing. For the probe molecules, multifunctional species were selected, such as a 2,4,6-trimercapto- 1,3,5-triazine (TMT), 4,5-diamine-2,6-dimercaptopyrimidine (DadMcP or Dad) and mercaptoethylpyrazine (PZT) which present thiol groups able to anchor onto gold nanoparticles, leaving available sites for further interaction with substrates and metal complexes. It was observed that the molecular shell in Turkevich\'s method is very dependent on the synthesis condition, being possible to detect the intermediate product of citrate oxidation reaction in the nanoparticle surface, under controlled conditions, dramatically influencing the SERS behavior. A systematic study was conduct with the probe molecule 2,4,6-trimercapto-1,3,5-triazine anchored to gold nanoparticles either by changing the passivating layer (citrate), or for in situ synthesis with and without a reducing agent. These systems were investigated under different conditions as SERS sensors for metals. This study was extended to the probe molecule 4,5-diamine-2,6-dimercaptopyrimidine, exploiting the influence of time in the coordination of such species and also the effect of different kinds of eletrolytes in the aggregation process. Finally, it has been presented strong evidences for the occurence of photoinduced processes involving functionalized nanoparticles with emphasis on mercaptoethylpyrazine, whose bahavior has proved to be very unusual, generating photoaggregated films under UV light influence, with possible applications in photolithography.

A study of the use of Surface Enhanced Raman Spectroscopy (SERS) for the detection of illicit drugs in oral fluid using metal enhancement mechanisms was undertaken. Initial work investigated ecstasy tablet composition using Raman to identify what drugs and excipients might be present in oral fluid samples obtained from users. Overall, it is possible to identify the presence of phenethylamines and excipients in the seized tablets but not categorically distinguish between the phenethylamine derivative(s) especially when in a mixture. Comparison of the overall batch average peak positions and peak responses of the phenethylamine derivatives and excipients shows variability across the batches and reveals trends within the sub-batches. The Raman spectra appear to reflect the findings of the GUMS analysis tentatively, implying this technique could be used for initial intelligence gathering applications whilst confirmatory analysis results are awaited. Initial SERS research focused on achieving enhancement of aqueous drug solutions with silver and gold colloid. Overall a lack of reproducibility was observed. Therefore, alternative SERS enhancement mechanisms were sought. Ag/Ti0₂ substrates demonstrated low limits of detection and the possibility of detecting SERS enhancement of aqueous amphetamine solution at levels below 8x10⁻² M. The work also showed that cotton swabs for sample application onto the surface of the substrate are a viable practical option for both experimental and field analysis. Successful detection of methadone and buprenorphine, used to treat heroin addiction, was achieved with Ag/Ti0₂ substrates at concentrations associated with therapeutic use, representing lower concentration drugs. The detection of MDMA in oral fluid following ecstasy use, not only showed promise for the detection of illicit drugs, but did so at the analytical cut-off concentration detailed in the draft type approval specification for roadside drug screening devices. This work confirms that SERS has a role for drug detection in oral fluid samples.

The tumour suppressor protein, p53, is either mutated or absent in over 50 % of cancers and is negatively regulated by the mouse double minute two protein, MDM2. This thesis presents a novel nanosensing approach to investigate full-length MDM2 interactions with p53, thus providing an allosteric assay for identifying novel binding ligands. SERS (Surface enhanced Raman scattering) - active nanoparticles, functionalized with a p53 peptide mimic, peptide 12.1, display biologically specific aggregation following addition of MDM2. The extent of nanoparticle assembly is altered following the introduction of various MDM2 binding ligands. This is the first study to report nanoparticle assembly through specific protein-peptide interactions which can be followed by SERS. This approach lends itself to the development of a screening assay for identifying new MDM2 inhibitory molecules and a pilot screen of natural products is completed. Owing to their biocompatibility, peptide functionalized nanoparticles have attracted increasing interest over the last decade for use in numerous biological applications applications. Controlling the assembly of peptide nanoparticles is of particular interest in the development of biocompatible nanomaterials. Coiled coil peptides have demonstrate highly specific binding activity in a variety of cellular functions and their structure is well understood. Work presented in chapter 4 of this thesis documents pH sensitive nanoparticle assembly driven by coiled coil heterodimer formation. SERSactive nanoparticles were functionalized with glutamic acid and lysine rich coiled coil peptides and assembly was observed, monitored using SERS, in heterogeneous solutions. This is the first instance of coiled coil directed assembly of silver nanoparticles followed by SERS.

The optimal surface enhanced Raman scattering (SERS) intensity was correlated to the localized surface plasmon resonance (LSPR) of individual and aggregated gold core/silver shell (Au@Ag) nanoparticles (NPs) in titrations involving the addition of both SERS label (e.g., rhodamine 6G, R6G) and the non-SERS active aggregant (chemical species that triggers the aggregation of NPs) potassium chloride (KCl). Titrating NP solutions with pure SERS label has often resulted in highly non-linear calibrations. In some cases, addition of non-SERS active aggregating agents such as KCl has also resulted in a large increase in SERS signals. An order of initial addition was followed in this report to find any advantage from the initial addition between the SERS label or the aggregant KCl. Interactions between Au@Ag solution and the SERS labels of R6G, 4 mercaptopyridine (MPY) and 4 mercaptobenzoic acid (MBA) were followed using spectrophotometric titrations. Evaluations of the role of aggregation in NP solutions were conducted through the micro-titrations using a quartz cuvette and in two separate stages: (1) a single amount of KCl was followed by increasing amounts of SERS label, and (2) a single amount of SERS label was followed by increasing amounts of KCl. The present reports allowed to conclude that the graphs of SERS intensity (λ _EX = 785nm, corrected for solution absorption) versus aggregate absorptions (λ_AG = 830 nm) had a correlation between intense SERS and LSPR band extinctions.

Através da modificação adequada da superfície de nanopartículas de ouro com uma molécula sulfurada que apresenta vários sítios de coordenação, foi possível desenvolver um conceito interessante de sensoriamento quantitativo conjugado ao efeito SERS. Estudos com sistemas desse tipo permitem explicar não apenas como uma molécula se liga a uma superfície, mas também como aproveitar essas informações para elaborar sensores de alta sensibilidade. Entretanto, as teorias eletrodinâmico-quânticas que regem as interações dos plasmons de superfície ainda estão sendo trabalhadas. Dessa forma, o presente trabalho procura explorar as teorias atuais sobre a origem dos plasmons e as interações plasmônicas entre as partículas. Essas interações promovem fenômenos de intensificação do espalhamento Raman por superfície e também foram discutidas. Visando conhecer e compreender os fenômenos envolvidos, foram sintetizadas nanopartículas de ouro estabilizadas com 2,4,6-trimercapto-1,3,5-triazina e estudada a química do ligante na superfície das nanopartículas de ouro. Além disso, foi estudada a influência dos equilíbrios ácido-base nos espectros SERS e monitorou-se as bandas mais diretamente sensíveis ao pH, associando as mudanças observadas aos diversos equilíbrios das espécies presentes em solução. Por fim, explorou-se o conceito de sensoriamento através das mudanças nos modos vibracionais dos espectros SERS, na formação de complexos em superfície.
Surface modification of gold nanoparticles with a molecule exhibiting several coordination points, allowed to elaborate an interesting concept for quantitative sensing conjugated with the SERS effect. In such systems it is important to know how the molecule binds to the surface, since, based on those informations one can elaborate sensors displaying high sensibility.. However, in dealing with the interaction of nanoparticles with light, the electrodynamic-quantum theories related to the interactions of the surface plasmons are not yet completely developed. In this way, in this t dissertation we made use of the current theories to understand the origin of the plasmons and of how they interact with the the nanoparticles. We have synthesized gold nanoparticles stabilized with 2,4,6-trimercapto-1,3,5-triazine and studied the ligand chemistry at the particles surface.. The influence of acid-base equilibria was studied based on the changes of the SERS spectra SERS with the pH, and interpreted in terms of the several equilibria of the species in solution. Finally, a new sensing concept, based on the observed changes in the SERS spectra in the presence of metal ions, was successfully demonstrated.

Desarrollo experimental de trabajo de titulación
En este trabajo se estudió el efecto del mejoramiento de la dispersión Raman por la superficie en soluciones diluidas de azul de metileno. Se usaron como sustratos nanoislas de oro obtenidas por evaporación térmica al alto vacío. El efecto mencionado, comúnmente conocido por sus siglas en inglés, efecto SERS (Surface-enhanced Raman Scattering), se estudió usando sustratos de oro depositados por evaporación térmica. El estudio se realizó en 5 etapas: En la primera etapa, se determinaron el disolvente, el volumen la solución y la temperatura del sustrato que permitieran que el analito, el azul de metileno, se pudiese colocar sobre un portaobjeto de manera uniforme. Esto es, evitando la formación de agregados de azul de metileno. Para ello se utilizó la espectroscopia Raman y microfotografías ópticas. En la segunda etapa, se demostró el efecto SERS, para ello se fue obteniendo el espectro Raman para diferentes diluciones. Se determinó que a la concentración de 10-5 molar el espectro Raman deja de observarse. Sin embargo al colocar la solución 10-5 molar sobre el sustrato SERS, la señal Raman se ve claramente. En la tercera etapa se determinó la dilución mínima detectable la cual fue de 10-20 Molar. En la cuarta etapa se estudió el efecto SERS como función de la longitud de onda y la mínima intensidad del haz láser. Observándose que para el azul de metileno sobre sustratos de oro, el efecto SERS va a depender en parte de la longitud de onda. Finalmente en la quinta etapa, se observó el efecto en una muestra biológica, la cual fue sangre, demostrándose que se puede detectar hemoglobina en concentraciones menores de 10-5 molar.
proyecto CONACyT No. A1-S-33899 proyecto PIIF-3-2018, PAPIIT-UNAM IN117116

Malgré d'importantes percées dans le domaine de la biodétection, nous avons toujours besoin de nouveaux capteurs qui faciliteraient la détection précoce de maladies graves comme le cancer. La biopsie tissulaire classique reste la référence dans de nombreux cas. Bien que cette approche ait montré son potentiel, elle reste invasive pour les patients et les techniques de détection sont fastidieuses ou manquent de sensibilité pour détecter la maladie à un stade précoce. La spectroscopie Raman a démontré son intérêt pour la biodétection. Sa capacité à caractériser la nature chimique, la structure et l'orientation d'un analyte, en fait un candidat idéal. Les pics Raman très nets d'une molécule peuvent être considérés comme une véritable empreinte digitale. Malheureusement, le signal Raman diffusé est extrêmement faible. Cette limitation a été surmontée par la spectroscopie Raman exaltée de surface (SERS), car elle augmente considérablement le signal Raman diffusé tout en maintenant la largeur des pics du spectre d'une molécule. Malheureusement, la plupart des substrats SERS actuels sont soit des surfaces métalliques nano-rugueuses en 2D soit des nanoparticules colloïdales, qui manquent de sensibilité et de fiabilité dans les mesures avec une faible répétabilité et reproductibilité des données. Ces dernières années, des fibres optiques spéciales ont été utilisées comme plateformes SERS. Elles comportent des trous qui s'étendent sur toute leur longueur. Ces trous permettent d'incorporer l'analyte à l'intérieur de la fibre. Ainsi, une telle plate-forme représente une alternative prometteuse aux substrats plans puisque l'analyte et la lumière d'excitation peuvent interagir sur une plus grande longueur à l'intérieur des fibres. De plus, les fibres optiques sont très flexibles, compactes, et permettent un guidage de la lumière à faible perte. Par conséquent, ces capteurs à fibres présentent à la fois les capacités de détection exceptionnelles du SERS, les avantages des fibres optiques et une sensibilité et une fiabilité améliorées. Dans ce manuscrit, nous visons à créer une plateforme de biodétection qui pourrait être utilisée dans un cadre clinique. Pour cela, nous proposons d'optimiser les caractéristiques d'une topologie de fibre déjà existante. Cela nous permet d'augmenter sa sensibilité tout en améliorant sa fiabilité et sa facilité d’utilisation. Grâce à ce capteur amélioré, nous avons pu pour la première fois détecter le biomarqueur du cancer de l'ovaire dans les fluides de kystes cliniques, ce qui nous a permis de différencier le stade du cancer. Par la suite, nous proposons une nouvelle topologie de fibre, spécifiquement conçue pour augmenter encore la sensibilité des sondes à fibre basées sur le SERS. Cette amélioration est réalisée en augmentant la surface d'interaction par rapport aux sondes à fibre standard. Pour cela, le diamètre du noyau est considérablement augmenté et la quantité de lumière qui interagit avec l'analyte est contrôlée avec précision. Nous envisageons que de tels capteurs à fibres fonctionnalisés puissent être incorporés à l'intérieur d'une aiguille de biopsie afin de créer un capteur deux-en-un pour la collecte et l’analyse de fluides corporels. Les limitations associées aux aiguilles de biopsie actuelles, qui exigent une collecte et une analyse des échantillons en deux étapes, pourraient ainsi être surmontées
Despite important breakthroughs in biosensing, we are still in need of new sensors that would facilitate the early detection of severe diseases such as cancer. Classical tissue biopsy remains the gold standard in many cases. Although this approach has shown its potential, it remains invasive for the patients and the detection techniques are either tedious or lack the sensitivity to detect the disease at an early stage. Raman spectroscopy has demonstrated its interests for biosensing. Its ability to characterize the chemical nature, structure and the orientation of an analyte makes it an ideal candidate. The sharp Raman peaks of a molecule can be seen as a true fingerprint. Regrettably, Raman scattered signal is extremely weak. This limitation was overcome by surface enhanced Raman spectroscopy (SERS), since it drastically increases the Raman scattered signal while maintaining the sharp peak of the fingerprint spectrum of a molecule. Unfortunately, most of the current SERS substrates are 2D nano-roughened metal surfaces or colloidal nanoparticles, which lack the sensitivity and reliability in measurement with poor repeatability and reproducibility in the data. In the recent years, special optical fibers have been used as SERS platforms. They feature holes that run along their entire length. These holes allow for the analyte to be incorporated inside the fiber. Thus, such platform represents a promising alternative to planar substrates since the analyte and the excitation light can interact for longer length inside the fibers. In addition, optical fibers are very flexible, compact and allow for low-loss light guiding. Therefore, such fiber sensors exhibit the outstanding detection abilities of SERS, the advantages of optical fibers and improved sensitivity and reliability. In this manuscript, we aim to create a biosensing platform that could be routinely used in a clinical setting. For that, we propose to optimize the features of an already reported fiber topology. This allows us to increase its sensitivity while simultaneously improving its reliability and practicability. With this improved sensor, for the first time, we could detect the biomarker for ovarian cancer in clinical cyst fluids, which allowed us to differentiate the stage of the cancer. Subsequently, we propose a novel fiber topology, specifically designed to further increase the sensitivity of SERS-based fiber probes. This is achieved by increasing the surface of interaction compared to standard fiber sensors. For that, the core diameter is significantly increased and the amount of light that interacts with the analyte is precisely controlled. We envision that such functionalized fiber sensors could be incorporated inside a biopsy needle to create a two-in-one sensor for body fluid collection and readout that can eventually overcome the limitations associated with existing biopsy needle platforms, which demands for two-step sample collection and readout

Ce travail de recherche s'inscrit dans le nouveau mouvement de réflexion qui vise à la réinsertion des oeuvres paléolithiques dans leurs contextes économiques, sociaux et culturels. À travers la recontextualisation spatio-temporelle du dispositif pariétal sculpté du site d'habitat solutréen du Roc-de-Sers (Charente), fouillé anciennement, l'auteur tente de mettre en évidence les enjeux de cette approche interdisciplinaire, fondamentale pour la caractérisation culturelle de l'art paléolithique. Cette dernière est envisagée non plus par le concept general de "style", qui lui confère une unité apparente dans une vaste vision évolutive ignorant le processus croissant de régionalisation, mais en intégrant l'art à des cultures déterminées par des systèmes techno-économiques complexes. Ainsi considérés, les rapports entre art et société tendent à abolir les cloisonnements établis, composés d'une infinité d'approximations symboliques et de rapprochements évolutifs hypothétiques, et renforcent l'identité symbolique de chaque groupe. Forte des observations recueillies sur les témoins les plus tangibles de l'unité techno-economique de ce site d'habitat, l'analyse techno- et morpho, stylistique des représentations sculptées de ce dispositif pariétal exemplaire a conduit à distinguer un ensemble de conventions stylistiques, qui s'est avéré constituer un cadre référentiel pertinent pour la détermination de l'art du solutréen supérieur. À la lumière de ces résultats, il a été possible de réinsérer le dispositif pariétal du Roc-de-Sers dans le cadre contextuel du solutréen franco-ibérique
This research study fits into the new-tought movement which aims at the paleolithic art works reinseration in their economic, social and cultural contexts. Trough the spatial-temporal recontextualization of the rock engraved art appliance of the solutrean establishment site of Roc-de-Sers (Charente), Formerly excavated, the author attempts to point out the stakes of that combined research approach, a basic one for the paleolithic art characterization. The latter is no more concerned with the general style-concept which confers to it a conspicuous unit in a large evolutive vision, neglecting the increasing regionalization process, but it incorporates the art into determinated cultures by technological-economical complexes systems. So estimated, the relations between art and society tempt to cancel the established partionings compound of endless symbolic approximations and evolutive assumed parallels, and reinforce the symbolic identity of each group. Relaying to the observations collected on the most tangible witnesses of this site establishment technological-economic unit, the technological, morphological and stylistic analysis of that exemplary rock art appliance engraved representations has led to dicern a stylistic conventions assemblage, which is proving to form a pertinent reference frame for the upper-solutrean art determination. On the light of these result it has been possible to reinsert the roc-de-sers rock art appliance in the French-Iberian solutrean contextual frame