Dissertations / Theses: 'SERS SUBSTRAT'

1

Gillibert, Raymond. "Développement d’un substrat SPRi/SERS pour des applications en détection moléculaire." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCD003/document.

Full text

Abstract:

Dans cette thèse, nous décrivons sommairement les techniques utilisées qui sont l’imagerie parrésonance plasmon de surface (SPRi) et la diffusion Raman exaltée de surface (SERS). Le butprincipal du projet Piranex dans lequel la thèse s’inscrit consiste au développement d’une biopucenanostructurée bimodale permettant le couplage des deux techniques SPRi et SERS. Cettebiopuce est constituée d’un film d’or par-dessus lequel nous avons déposé un réseau carré denanocylindres en or. Un ensemble d’études ont été effectuées pour caractériser ses propriétésplasmoniques du biocapteur afin d’en optimiser le signal SERS. Nous avons ainsi constaté quel’émission du signal était fortement anisotrope, dus à l’excitation du Mode de Bragg et que lechamp proche était principalement exalté sur les bords de la nanostructure. Les propriétés furentégalement comparées avec celles de réseaux identiques déposés directement sur un substrat diélectrique.Par la suite un ensemble d’études plasmoniques et SERS ont été effectuées pourl’aluminium, autre matériaux plasmonique d’intérêt. Enfin, un protocole de détection par SERSde l’ochratoxine basé sur un aptamère fut développé et a permis la détection de l’ochratoxine dès10 pM, bien en dessous de la limite autorisée par les organismes de régulation en agroalimentaire
In this thesis, we briefly describe the techniques used, which are surface plasmon resonanceimaging (SPRi) and surface enhanced Raman scattering (SERS). The main goal of the Piranexproject in which the thesis is based is the development of a bimodal nanostructured biochipallowing the coupling of the two techniques SPRi and SERS. This bio-chip consists of a goldfilm over which we have deposited a square array of gold nanocylinders. A set of studies hasbeen carried out to characterize plasmonic properties of the biosensor in order to optimize theSERS signal. We have thus found that the emission of the signal was strongly anisotropic, due tothe excitation of the Bragg Mode and that the near field was mainly enhanced on the edges of thenanostructure. The properties were also compared with those of identical gratings depositeddirectly on a dielectric substrate. Subsequently a set of plasmonic and SERS studies were carriedout for aluminum, other plasmonic materials of interest. Finally, a detection protocol by SERS ofochratoxin based on an aptamer was developed and allowed the detection of ochratoxin with adetection threshold of 10 pM, well below the limit allowed by food regulatory agencies

APA, Harvard, Vancouver, ISO, and other styles

2

Dridi, Hamida. "Méthodologies pour la réalisation d'un substrat SERS à base de silicium poreux pour la détection de molécules chimiques et biologiques." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S012/document.

Full text

Abstract:

Le travail de cette thèse porte sur la réalisation de substrats SERS (Surface Enhanced Raman Scattering) pour la détection d'espèce chimiques et biologiques. Il s'agit de mettre en place des méthodologies utilisant comme surface de départ celle d'une couche poreuse de silicium et un effet de Plasmon de surface induit par la présence d'un métal noble en général. Les spécificités des couches poreuses qui sont d'une part une rugosité nanométrique et d'autre part une porosité et donc une surface interne modulable ont une incidence directe sur la sensibilité de détection de molécules cibles. Nous avons développé dans ce manuscrit de thèse différentes méthodes d'élaboration de substrats SERS à base de couches poreuses de silicium. Nous avons envisagé deux voies, la première se base sur l'utilisation des nanoparticules d'or en solution colloïdale. La deuxième voie, plus originale, utilise le dépôt d'or par pulvérisation cathodique sur une couche poreuse préparée sur la face rugueuse de silicium. Des résultats SERS intéressants, concernant la détection de molécules chimique (Rhodamine 6G) et biologique (Albumine Sérum Bovin), ont été décrits et expliqués permettant d'envisager diverses solutions afin de les optimiser
The work of this thesis focuses on the realization of SERS substrates (Surface Enhanced Raman Scattering) for the detection of chemical and biological species. This is to implement the methodologies using as the starting surface of a porous silicon layer and a surface Plasmon effect induced by the presence of a noble metal in general. The specificities of the porous layers which are firstly a nanometer roughness and secondly a porosity and therefore an inner surface have a direct impact on the target molecule detection sensitivity. We have developed in this PhD thesis different substrates development methodologies SERS-based on porous silicon layers. We considered two ways, the first is based on the use of gold nanoparticles in colloidal solution. The second route, more original, uses the deposition of gold by sputtering on a porous layer prepared on the rough side of a silicon wafer. Interesting SERS results regarding the detection of chemical (Rhodamine 6G) and biological (Bovin Serum Albumin) molecules, have been described and explained for considering various solutions to optimize them

APA, Harvard, Vancouver, ISO, and other styles

3

Iakab, Stefania-Alexandra. "Gold-Coated Black Silicon Nanostructured Surfaces for SERS and SALDI-MS Multimodal Imaging of Biological Applications." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672198.

Full text

Abstract:

La caracterització in situ de la composició molecular dels teixits biològics és indispensable en la investigació clínica, farmacèutica i forense. Les tècniques d’imatge molecular, com l’espectrometria de masses d’imatge i les imatges per espectroscòpia Raman, empren materials nanoestructurats per abordar reptes com la baixa sensibilitat, l’especificitat i la resolució lateral. L’objectiu d’aquesta tesi és dissenyar, fabricar, avaluar i aplicar un substrat nanoestructurat basat en or i silici (que denominem “AuBSi”) compatible amb aplicacions d’espectrometria de masses d’imatges per desorció/ionització per làser assistides per superfície (SALDI-MS) i espectroscòpia Raman intensificada per superfície (SERS). Els resultats demostren que el substrat AuBSi és reproduïble, fàcil de fer servir, rendible i altament fiable. Assegura una fàcil preparació de la mostra i és totalment compatible amb les dues modalitats d’imatge, cosa que permet un enfocament veritablement multimodal. Mostrem que hi ha una unificació entre els formats de dades SALDI i SERS que permet la integració completa del flux de treball de processament d’imatges i el co-registre d’imatges.. S’han provat les capacitats d’obtenció d’imatges del substrat AuBSi en diverses solucions d’estàndards, seccions histològiques de teixit animal (fetge, ronyó i cervell de ratolí) i empremtes dactilars. L’anàlisi multimodal d’empremtes dactilars va destacar les excel·lents capacitats del substrat per acoblar imatges SALDI i SERS, alhora que s’aconsegueix pal·liar les limitacions de cada tècnica. Així doncs, el substrat AuBSi desenvolupat en aquesta tesi facilita els estudis de metabolòmica in situ dirigits i/o no dirigits per a diversos camp com la investigació clínica, medioambiental, forense i farmacèutica.
La caracterización in situ de la composición molecular de los tejidos biológicos es indispensable en la investigación clínica, farmacéutica y forense. Las técnicas de imagen molecular, como la espectrometría de masas de imagen y las imágenes por espectroscopia Raman, emplean materiales nanoestructurados para abordar desafíos como la baja sensibilidad, la especificidad y la resolución lateral. El objetivo de esta tesis es diseñar, fabricar, evaluar y aplicar un sustrato nanoestructurado basado en oro y silicio (que denominamos “AuBSi”) compatible con aplicaciones de espectrometría de masas de imágenes por desorción / ionización por láser asistidas por superficie (SALDI-MS) y espectroscopía Raman intensificada por superficie (SERS). Los resultados demuestran que el sustrato AuBSi es reproducible, fácil de usar, rentable y altamente confiable. Garantiza una fácil preparación de la muestra y es totalmente compatible con ambas modalidades de imagen, lo que permite un enfoque verdaderamente multimodal. Mostramos que existe una unificación entre los formatos de datos SALDI y SERS, que permite la integración completa del flujo de trabajo de procesamiento de imágenes y el coregistro de imágenes.Se han probado las capacidades de obtención de imágenes del sustrato AuBSi en varias soluciones de estándares, secciones histológicas de tejido animal (hígado, riñón y cerebro de ratón) y huellas dactilares. El análisis multimodal de huellas dactilares destacó las excelentes capacidades del sustrato para acoplar imágenes SALDI y SERS, al tiempo que se consiguen paliar las limitaciones de cada técnica. Así, el sustrato AuBSi desarrollado en esta tesis facilita los estudios de metabolómica in situ dirigidos y / o no dirigidos para diversos campos como la investigación clínica, medioambiental, forense y farmacéutica.
Characterising in situ the molecular composition of biological tissues is an indispensable tool in clinical, pharmaceutical and forensic research. Imaging modalities such as mass spectrometry imaging and Raman spectroscopy imaging employ nanostructured materials for addressing challenges such as low sensitivity, specificity and lateral resolution. The aim of this thesis is to design, fabricate, evaluate and apply a gold- and silicon-based nanostructured substrate (named AuBSi) compatible with surface-assisted laser desorption/ionization (SALDI) and surface-enhanced Raman spectroscopy (SERS) imaging applications. Results demonstrate that the AuBSi substrate is reproducible, user-friendly, cost effective and highly reliable. It ensures easy sample preparation and is fully compatible with both imaging modalities, enabling a genuine multimodal approach. We show that there is a unification between SALDI and SERS data formats that allows the full integration of the image processing workflow and the straightforward coregistration of images. We tested the imaging capabilities of the AuBSi on several standard solutions, animal tissue sections (mouse liver, kidney and brain) and fingerprints. The multimodal analysis of fingerprints highlighted the excellent capabilities of the substrate to couple SALDI and SERS imaging, while dealing with the challenges of each technique. Thus, the AuBSi substrate developed in this thesis facilitates targeted and/or untargeted in situ metabolomics studies for various fields such as clinical, environmental, forensics, and pharmaceutical research.

APA, Harvard, Vancouver, ISO, and other styles

4

Azziz, Aicha. "Étude structurale des brins d'ADN et de leurs interactions par diffusion Raman exaltée de surface." Electronic Thesis or Diss., Le Mans, 2024. https://cyberdoc-int.univ-lemans.fr/Theses/2024/2024LEMA1024.pdf.

Full text

Abstract:

Le développement de méthodes rapides et sensibles de détection et d’étude de l’ADN suscite un intérêt croissant notamment dans le domaine biomédical pour le diagnostic moléculaire.Dans ce cadre, la technique de diffusion Raman exaltée de surface (SERS) s’est révélée être un outil idéal pour l'étude de la structure des brins d'ADN et des interactions moléculaires entre deux brins d'ADN.Dans un premier temps, nous avons évalué les capacités de détection de plusieurs substrats SERS commerciaux en utilisant une solution diluée de 4-MBA. Cette étude nous a permis de déterminer quel substrat présentait les meilleures performances SERS et lequel pouvait être exploité pour l'étude des brins d'ADN. Des nanoparticules colloïdales ont également été utilisées pour travailler en milieu liquide.Les signatures spectrales de plusieurs séquences d'ADN ont été étudiées avec des séquences monobases ou polybases. Nous avons pu obtenir des spectres de référence pour chaque base et montrer une dépendance du signal en fonction de la séquence.La caractérisation spectrale des brins d'ADN avant et après hybridation avec un brin complémentaire nous a permis de suivre les changements structuraux des brins d'ADN induits par l'hybridation. Nous avons pu mettre en évidence des modifications de l’orientation ou la diminution de la flexibilité des brins lors de l’hybridation en absence et en présence des mésappariements. Grace à l’utilisation d’outils d’analyses comme l'analyse par composante principale, il a été possible d’analyser et interpréter les données et de proposer des modèles d'interaction moléculaire
The development of rapid and sensitive methods for DNA detection and analysis is gaining increasing interest, particularly in the biomedical field for molecular diagnostics.In this context, surface-enhanced Raman scattering (SERS) has proven to be an ideal tool for studying the structure of DNA strands and the molecular interactions between two DNA strands.Initially, we assessed the detection capabilities of several commercial SERS substrates using a diluted 4-MBA solution. This study allowed us to determine which substrate exhibited the best SERS performance and could be exploited for the study of DNA strands. Colloidal nanoparticles were also employed for experiments in liquid media.The spectral signatures of several DNA sequences were studied using monobase or polybase sequences. We were able to obtain reference spectra for each base and demonstrate a signal dependency based on the sequence.Spectral characterization of DNA strands before and after hybridization with a complementary strand allowed us to track structural changes in the DNA strands induced by hybridization. We were able to highlight modifications in orientation or reduced flexibility of the strands during hybridization, both in the presence and absence of mismatches. Through the use of analytical tools such as principal component analysis, it was possible to analyze and interpret the data, leading to proposed models of molecular interaction

APA, Harvard, Vancouver, ISO, and other styles

5

Rahmani, Meryem. "Analyses Raman multispectrales exaltées pour la détection de molécules sous forme de trace." Electronic Thesis or Diss., Le Mans, 2024. http://www.theses.fr/2024LEMA1004.

Full text

Abstract:

Au cours des dernières décennies, l'utilisation des produits phytosanitaires communément appelés pesticides a augmenté. Ces substances sont devenues de plus en plus présentes dans notre environnement, s’'accumulant ainsi dans les sols, l'air et les eaux. Ces produits, même en très faible concentration, représentent un danger pour la santé humaine, végétale et animale. Pour toutes ces raisons il est important d'encadrer l'utilisation des produits phytosanitaires en interdisant l'utilisation de certaines de ces substances et en mettant en place des réglementations pour fixer les Limites Maximales de Résidus (LMR). Il est aussi nécessaire de développer de nouvelles méthodes de détection et d’identification de polluants à l'état de trace car les techniques conventionnelles nécessitent de gros équipements de laboratoire qui ne sont pas compatibles avec des analyses sur site.Dans le cadre de nos travaux, nous utilisons la Diffusion Raman Exaltée de Surface (DRES) pour détecter et identifier des molécules à l’'état de trace. Nous avons étudié et analysé les performances de trois substrats DRES commerciaux (Hamamatsu, SERSitive et Ocean Insight) pour la détection et l'identification d'une molécule modèle à des concentrations de l'ordre de 10-6 M et 10-8 M. Nous avons comparé les réponses Raman à partir des cartographies enregistrées sur leurs surfaces à deux longueurs d’onde incidentes. Nous avons également développé et optimisé des supports métalliques nanorugueux capables de détecter et identifier des molécules avec une limite de détection à 10-9 M. Nous présenterons le protocole expérimental utilisé pour fabriquer ces substrats nanorugueux en or. Ensuite, nous avons étudié les propriétés topographiques des surfaces pour mieux comprendre les propriétés d'exaltation des substrats. Ces derniers sont analysés par microscopie électronique à balayage et par microscopie à force atomique (AFM). Les réponses optiques des supports nanorugueux sont étudiées en champ proche par photoémission d’électrons (PEEM) et en champ lointain par spectrométrie Raman une fois ces supports mis en contact avec des solutions contenant des molécules à très faibles concentrations. Nous avons comparé la réponse spectrale, les distributions d'intensité, et la stabilité sous faisceau laser, des substrats nanorugueux en or et le substrat le plus efficace parmi les trois substrats DRES commerciaux en analysant les spectres Raman à une concentration de 10-8 M.La stabilité de la réponse Raman des substrats DRES commerciaux et du substrat nanorugueux optimisé a été étudiée dans le temps, pendant une durée de plusieurs mois. Avec le temps, l'efficacité des substrats diminue et il n'est alors plus possible de détecter la présence des molécules. Nous avons développé une méthode qui permet d'améliorer les performances Raman de ces substrats vieillis. Les performances de ces substrats améliorés ont été étudiées en analysant les distributions d'intensité Raman à partir d'imagerie contenant plusieurs centaines de spectres. Nous avons utilisé les substrats nanorugueux en or pour détecter les molécules présentes dans un mélange binaire de molécules modèles à une concentration de 10-8 M. Nous avons analysé les cartographies Raman en utilisant des outils chimiométriques, à savoir l’'Analyses en Composantes Principales (ACP), et la Multivariate Curve Resolution (MCR)
In recent decades, the use of phytosanitary products commonly called pesticides has increased. These substances have become increasingly present in our environment, accumulating in soil, air and water. Even at very low concentration these products represent a danger to human, plant and animal health. For all these reasons it is important to regulate the use of phytosanitary products by prohibiting the use of certain of these substances and by strengthening regulations to set Maximum Residue Limits (MRLs) as low as possible. It is also necessary to develop new methods for detecting and identifying trace pollutants because conventional techniques require large laboratory capabilities which are not compatible with on-site analyses.In my PhD. work, we have used Surface Enhanced Raman Scattering (SERS) to detect and identify trace molecules. We studied and analyzed the performance of three commercial DRES substrates (Hamamatsu, SERSitive and Ocean Insight) for the detection and identification of a model molecule at concentrations of the order of 10-6 M and 10-8 M. We compared the Raman responses from the Raman maps recorded on their surfaces at two incident wavelengths. We have also developed and optimized efficient nanorough metallic substrates to detect and identify molecules with a detection limit of 10-9 M. We will present the experimental protocol used to fabricate our nanorough gold substrates. The topographical properties of the surfaces were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to better understand the reason of SERS properties of the substrates. The optical responses of our nanorough substrates were studied in the near field by electron photoemission (PEEM) and in the far field by Raman spectrometry after putting them in contact with solutions containing molecules at very low concentrations. We compared the spectral response, intensity distributions, and stability under laser beam, of gold nanorough substrates and the most efficient substrate among the three commercial DRES substrates by analyzing the Raman spectra at a concentration of 10-8 M.The stability of the Raman response of the commercial SERS substrates and our optimized nanorough substrates was studied over time, for a period of several months. The effectiveness of the substrates decreases over time and it is no longer possible to detect the presence of the molecules after several months. In my PhD work we have tested a method that makes it possible to improve the Raman performance of these aged substrates. The performance of these improved substrates was studied by analyzing Raman intensity distributions from imaging containing several hundred spectra. Finally, we used the gold nanorough substrates to detect molecules present in a binary mixture of model molecules at a concentration of 10-8 M. We analyzed the Raman maps using chemometric tools, namely Component Analysis. Principal (ACP), and Multivariate Curve Resolution (MCR)

APA, Harvard, Vancouver, ISO, and other styles

6

Michel, Beat A. "Phénomène, sens et substrat : pour une métaphysique phénoménologique." Thesis, Paris 10, 2020. http://www.theses.fr/2020PA100056.

Full text

Abstract:

Quel est le substrat de la conscience, ou encore « qu’est-ce qui fait la conscience » ? Poser cette question revient à ne pas se satisfaire d'une réponse, qui peut paraître aller de soi, affirmant que ce substrat est le cerveau. En fait, situer le substrat de la conscience dans le corps objectif, comme partie du monde – que ce soit dans le contexte de la phénoménologie, de la philosophie de l’esprit ou du naturalisme – mène à une ontologie circulaire : la conscience dans le corps, le corps dans le monde, le monde pensé, perçu, conçu, constitué par la conscience. Or, même si toute circularité n’est pas nécessairement problématique, nous cherchons à montrer que cette circularité d’une ontologie générale est bien rédhibitoire. Aussi, nous empruntons une autre voie, partant du corps subjectif vers un substrat qui n’est pas situé dans le monde. Le concept de substrat transcendantal est construit en opérant deux fusions consécutives de concepts existants. Il s’agit d’abord de réunir en un seul concept, celui de substrat abstrait, le hylémorphisme aristotélicien, d’une part, et l’idée de survenance issue de la philosophie de l’esprit, d’autre part, en établissant que les deux sont, d’une certaine manière, coextensifs. Nous faisons ensuite appel à la notion de Vie absolue, introduite par Michel Henry dans la dernière période de son œuvre, en l’interprétant comme un cas particulier de la notion de substrat abstrait. Le résultat de cette deuxième unification conceptuelle, nous l’appelons substrat transcendantal – transcendantal au sens kantien. Enfin nous utilisons le terme d’adhérence pour désigner l’expérience vécue que fait le sujet transcendantal du substrat transcendantal
What is the substrate of consciousness, or what is it that “makes consciousness”? Asking this question amounts to not being satisfied with an answer that may seem self-evident: this substrate is the brain. In fact, situating the substrate of consciousness in the objective body, as part of the world - whether in the context of phenomenology, philosophy of mind or naturalism - leads to a circular ontology: consciousness in the body, the body in the world, the world thought, perceived, conceived, constituted by consciousness. However, even if all circularity is not necessarily problematic, we seek to show that this circularity of a general ontology is indeed fatal. So we take another path, from the subjective body to a substrate that is not located in the world. This substrate is constructed as an abstract notion, by operating two consecutive merges of existing concepts. First we bring together in a single concept, that of abstract substrate, the Aristotelian hylemorphism, on the one hand, and the idea of supervenience, from the philosophy of the mind, on the other hand, by establishing that the two are, in a way, coextensive. We then appeal to the notion of absolute Life, introduced by Michel Henry in the last period of his work, interpreting it as a particular case of the notion of abstract substrate. The result of this second conceptual unification, is what we call transcendental substrate - transcendental in the Kantian sense. Finally we use the term adherence to designate the lived experience that the transcendental subject makes of the transcendental substrate

APA, Harvard, Vancouver, ISO, and other styles

7

Speed, Jonathon. "Tailoring plasmonic substrates for SERS." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/191315/.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

8

Eliasson, Kasper. "Quantification using SERS on a colloidal substrate." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-443582.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

9

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

10

Sharma, Narayan. "Solution Processable Surface Enhanced Raman Spectroscopy (SERS) Substrate." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1434375587.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Ahmad, Hossam [Verfasser], Heinz-Detlef [Akademischer Betreuer] Kronfeldt, Ulrike [Akademischer Betreuer] Woggon, and Frank [Akademischer Betreuer] Hubenthal. "Gold substrates for SERS and SERS/SERDS measurements in seawater and Raman measurements through long optical fibers / Hossam Ahmad. Gutachter: Heinz-Detlef Kronfeldt ; Ulrike Woggon ; Frank Hubenthal." Berlin : Technische Universität Berlin, 2014. http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-48713.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Ahmad, Hossam [Verfasser], Heinz-Detlef Akademischer Betreuer] Kronfeldt, Ulrike [Akademischer Betreuer] [Woggon, and Frank [Akademischer Betreuer] Hubenthal. "Gold substrates for SERS and SERS/SERDS measurements in seawater and Raman measurements through long optical fibers / Hossam Ahmad. Gutachter: Heinz-Detlef Kronfeldt ; Ulrike Woggon ; Frank Hubenthal." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1065669534/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Ahmad, Hossam Verfasser], Heinz-Detlef [Akademischer Betreuer] Kronfeldt, Ulrike [Akademischer Betreuer] [Woggon, and Frank [Akademischer Betreuer] Hubenthal. "Gold substrates for SERS and SERS/SERDS measurements in seawater and Raman measurements through long optical fibers / Hossam Ahmad. Gutachter: Heinz-Detlef Kronfeldt ; Ulrike Woggon ; Frank Hubenthal." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1065669534/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Marotta, Nicole Ella. "Patterned nanoarray sers substrates for pathogen detection." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37274.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

15

Mahajan, Sumeet. "Engineering substrates for SERS : Fundamentals and applications." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533255.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Callahan, Jordan J. "Silver-embedded ZSM-5 Zeolites: a Reliable SERS Substrate." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342104242.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Pereira, Anderson de Jesus. "Substratos vítreos com nanoestruturas metálicas para aplicações SERS." Universidade Federal de Viçosa, 2016. http://www.locus.ufv.br/handle/123456789/9872.

Full text

Abstract:

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-03-23T17:48:32Z No. of bitstreams: 1 texto completo.pdf: 5471239 bytes, checksum: 75e65b6389b6e94ee7f496ab984437dd (MD5)
Made available in DSpace on 2017-03-23T17:48:32Z (GMT). No. of bitstreams: 1 texto completo.pdf: 5471239 bytes, checksum: 75e65b6389b6e94ee7f496ab984437dd (MD5) Previous issue date: 2016-08-25
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.

APA, Harvard, Vancouver, ISO, and other styles

18

Han, Sungyub. "Optimization of Aggregating agents and SERS Substrates for SERS detection of Cotinine and trans 3'-hydroxycotinine." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5499.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

19

Wilhelm, Manon. "Development of SERS substrates of metal nanoparticles and textile fibers." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15336.

Full text

Abstract:

Mestrado em Ciência e Engenharia de Materiais
Noble metallic nanostructures are well-known materials that present interesting physical and chemical properties, especially the surface plasmon resonance involved in the surface-enhanced Raman signal (SERS) of molecules adsorbed at the metal surface. Since its discovery, the SERS method is a highly studied analysis technique that allows detecting molecules at very low concentration. Numerous works are currently leaded to develop more efficient SERS substrates to lower the detection limit. Also, the development of more convenient substrates, eventually coupled with portable Raman technology is promising for the detection of low concentrated molecules in multiple domains, as for example the detection of dyes. This report presents the study of new nanocomposites with texile fibers for their use as SERS substrates. A literature review about natural fibers, metallic nanoparticles, nanocomposites and SERS technique will first be presented to contextualize this research. Then, several combinations of composites were prepared with natural fiber matrix of linen, silk or cotton. To prepare the nanocomposites, gold and silver nanoparticles were synthesized by the citrate method and have a mean size of respectively 14 nm and 86 nm. Then, three techniques of synthesis are used to produce the nanocomposites; namely the blending of fibers and metal colloids previously prepared, with and without modification of the fiber’s surface with polyelectrolytes, and the in situ synthesis of the particles in presence of the fibers. The nanocomposites were then characterized by several techniques such as scanning electron microscope, X-ray diffraction and optical measurements. The molecular probe used to evaluate the quality of the composites as SERS substrates was methylene blue (MB). This molecule has a strong SERS signal and is a dye frequently used in textile industry. Mapping studies of the composites were performed, using Raman confocal microscopy with MB as molecular probe. These studies allowed monitoring the distribution of the metallic nanoparticles at the fiber’s surface, as well as the presence of MB. The results showed that the detection of MB through this technique strongly depends on the type of nanocomposite, knowing that the composites with silver presented a better SERS signal of MB than the similar material with gold. Particularly, the composites of linen and silver presented very promising results as SERS substrates for the detection of MB.
As nanopartículas de prata e ouro são materiais que exibem propriedades físicas e químicas muito interessantes, nomeadamente as que se encontram associadas a efeitos de superfície como por exemplo na obtenção de espetros de Raman de moléculas adsorvidas na superfície de metais, originando sinais por intensificação por superfície (SERS: Surface-enhanced Raman scattering). Desde a sua descoberta, o efeito de SERS tem sido aproveitado em técnicas de análise e deteção de analitos em concentração muito baixa nas respetivas soluções. Um aspeto muito relevante em termos de desenvolvimento de novos materiais é a investigação de substratos mais eficientes para SERS. Além disso, o desenvolvimento de substratos mais convenientes, eventualmente acoplados a instrumentos de Raman portáteis é também promissor para a deteção de baixas concentrações de moléculas em múltiplas áreas, como por exemplo a deteção de corantes. Esta dissertação de Mestrado apresenta estudos em novos nanocompósitos à base de fibras têxteis e nanopartículas metálicas, tendo em vista a sua utilização como substratos para SERS. Primeiramente é apresentada uma revisão bibliográfica sobre fibras naturais, nanopartículas metálicas, nanocompósitos e a técnica de SERS, de modo a contextualizar o trabalho de investigação. Este envolveu numa primeira fase a preparação de nanocompósitos à base de fibras naturais, tais como o linho, a seda e o algodão. Utilizaram-se para o efeito nanopartículas coloidais de Au e Ag obtidas pelo método de citrato, com tamanho médio de 14 e 86 nm, respetivamente. Seguidamente, exploraram-se três técnicas preparativas para obter os nanocompósitos, nomeadamente a mistura das fibras e os coloides metálicos previamente preparados, com e sem modificação prévia da superfície das fibras com polieletrólitos e, ainda, a síntese in situ das nanopartículas na presença das fibras. Os nanocompósitos foram caracterizados por diversas técnicas, tais como microscopia eletrónica de varrimento, difração de raio-X e espetroscopia eletrónica. Em particular, realizaram-se estudos detalhados de espetroscopia de Raman explorando o efeito de SERS e usando o azul de metileno (MB) como analito. Esta molécula origina um sinal de SERS intenso sendo um corante frequentemente utilizado na indústria têxtil. Realizaram-se ainda estudos pioneiros no mapeamento destes materiais, usando o MB como sonda molecular, utilizando microscopia confocal de Raman. Estes estudos permitiram igualmente investigar a distribuição das nanopartículas metálicas na superficie das fibras bem como a presença do MB. Os resultados indicaram que a deteção de MB por esta técnica depende fortemente do tipo de nanocompósito, sendo que os nanocompósitos contendo prata apresentaram melhor sinal de SERS para a deteção do MB em comparação com os materiais análogos de ouro. Em especial, os nanocompósitos de linho e prata originaram resultados muito promissores como substratos de SERS na deteção do MB.

APA, Harvard, Vancouver, ISO, and other styles

20

Merces, Leandro 1989. "Nanomembranas tensionadas : ilhas de InAs em substratos complacentes de Si e microtubos metálicos enrolados como um sensor SERS para monocamadas auto organizadas." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276952.

Full text

Abstract:

Orientadores: Christoph Friedrich Deneke, Eduardo Granado Monteiro da Silva
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-25T16:50:29Z (GMT). No. of bitstreams: 1 MercesSilva_Leandrodas_M.pdf: 8926273 bytes, checksum: 010f49f410852b0ba0278adfc3e091fa (MD5) Previous issue date: 2014
Resumo: Nanomembranas livres são definidas como filmes ultrafinos constituídos por metais, óxidos ou semicondutores, com espessuras nanométricas e vastas áreas superficiais. São obtidas em geral por um processo de subcorrosão seletiva de uma camada de sacrifício, cujo papel é liberá-las gradualmente, permitindo que o relaxamento da energia elástica nelas armazenada aconteça de maneira controlada, garantindo a integridade final das estruturas. Neste trabalho, nanomembranas livres de Si suportadas por um substrato de SOI foram utilizadas como substratos complacentes para o crescimento de ilhas de InAs em uma câmara de MBE. Além disso, nanomembranas metálicas tensionadas (Ag/Ti/Cr/Ag) foram utilizadas na obtenção de microtubos metálicos enrolados. Análises detalhadas da morfologia das amostras, das estruturas das ilhas e dos microtubos, do strain em ambos os sistemas e de suas possíveis aplicações foram realizadas. A microscopia eletrônica de varredura mostrou que as estruturas permaneceram íntegras após as deformações. A microscopia de força atômica revelou uma baixa densidade de ilhas no topo das nanomembranas de Si. Ademais, possibilitou o aperfeiçoamento de parâmetros superficiais das nanomembranas metálicas e o enrolamento de microtubos com diâmetros pré definidos, garantindo convergência com o modelo analítico. Técnicas de difração de raios X e modelagem por elementos finitos foram utilizadas para elucidar os estados de strain observados em ambas as estruturas. As simulações das curvaturas do substrato complacente de Si e do microtubo metálico sugeriram, respectivamente, um gradiente de strain dependente da posição lateral de cada ilha na nanomembrana e coeficientes de strain constantes nas nanomembranas de Ti e Cr. Finalmente, cálculos envolvendo elasticidade contínua sugeriram que para uma nanomembrana de Si com espessura adequada, o InAs pode transferir strain suficiente para possibilitar o crescimento epitaxial coerente. Ainda, medidas de espectroscopia Raman em moléculas auto organizadas de 1-octadecanethiol, adsorvidas em Ag e aprisionadas entre as paredes dos microtubos metálicos, sugeriram que tal sistema pode ser utilizado como um dispositivo SERS para self-assembled monolayers
Abstract: Freestanding nanomembranes (NMs) are defined as metallic, semiconductor or oxide ultrathin films with nanometer thickness and macroscopic surface areas. In general, they are obtained by a process of selective underetching of a sacrificial layer, whose role is gradually release them, allowing relaxation of their stored elastic energy in a controlled way, ensuring integrity of the final structure. In this work, freestanding edge-supported Si nanomembranes are used as compliant substrate to the InAs growth on a SOI substrate in a MBE chamber. Furthermore, strained metallic nanomembranes (Ag / Ti / Cr / Ag) are used to obtain rolled-up metallic microtubes. A detailed analysis of sample morphology, InAs island and metallic microtube structure, strain on both systems and their possible applications is carried out. Scanning electron microscopy shows the structures stay intact during and after deformation. Atomic force microscopy reveals a lower island density on the top of the freestanding membranes. Moreover, it allowed optimizing the surface parameters of the strained metallic membranes, rolling-up tubes with pre-defined diameters and ensuring convergence with the proposed analytical model. X-ray diffraction and finite element modeling is used to elucidate the observed strain states in both structures. The bending simulations of compliant Si substrate and rolled up metallic microtube suggest, respectively, a lateral strain distribution depending on the island position on the freestanding membrane and a constant strain distribution on the Ti/Cr strained NMs. Finally, continuous elasticity calculations suggest that for a Si nanomembrane with adequate thickness, the InAs can transfer enough strain to enable coherent epitaxial growth. In addition, Raman spectroscopy measurements of 1-octadecanethiol self-assembled molecules adsorbed on an Ag nanomembrane and trapped between the microtube Ag walls suggest the system could be used as a SERS sensor for self-assembled monolayers
Mestrado
Física
Mestre em Física

APA, Harvard, Vancouver, ISO, and other styles

21

Wijesuriya, Shavini. "Fabrication and optimisation of SERS substrates for medical diagnostics and monitoring." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12694.

Full text

Abstract:

Surface enhanced Raman spectroscopy (SERS) has great potential for design of next generation point-of-care (POC) diagnostic devices. However, its practical application in medical diagnosis is limited due to high cost of SERS substrates. The goal for this thesis was to develop affordable SERS substrates, and demonstrate their efficacy in the detection and assay of a Raman probe and diabetes biomarkers, using 514nm and 1064nm Raman spectrometers. Rapid and less energy intensive methods were optimised for manufacturing three categories of SERS substrates: 1) chemically roughened silver (Ag) metal, 2) Ag and gold (Au) nanoparticles (NPs) prepared using microemulsions, and 3) Ag and Au NPs’ coated insoluble electrospun membranes. Immersion of Ag metal for 30 seconds in ammonia (NH4OH), followed by 10 seconds in nitric acid (HNO3) produced optimum roughened Ag metal SERS substrates. For synthesis of gold (Au) and Ag NPs, microemulsion compositions were varied, and the use of sodium borohydrate (NaBH4) produced the desired larger sizes and anisotropic shapes of the NPs. Nanostructured planar SERS structures based on insoluble electrospun membranes, were prepared by covalently binding Au or Ag NPs, on electrospun poly acrylic acid-ethylene glycol (PAA-EG) fibres. Ag metal SERS substrates provided the best SERS enhancement for the Raman probe molecule, 4-methylbenzenethiol (MBT), with a detection limit of 1aM, using 514nm Raman spectrometer. The Ag metal SERS substrates were then used to demonstrate proof-of-concept for the use of SERS for assay of diabetes biomarkers. The higher laser intensity of 106nm Raman caused burning of the dry NPs’ incorporated SERS substrates; but the thermally conductivity of solid Ag in Ag metal SERS substrate allowed SERS detection of 1nM MBT. To conclude, chemically roughened Ag metal SERS substrates proved cost effective and robust for quantitative SERS detection of MBT and diabetes biomarkers both with 514nm and 1064nm Raman spectrometers.

APA, Harvard, Vancouver, ISO, and other styles

22

Pelfrey, Suzanne Helen. "Tuneable photonic crystal structures as highly reproducible surface enhanced Raman (SERS) substrates." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494729.

Full text

Abstract:

SERS is a very useful analytical technique which was discovered over 30 years ago, however it has never fulfilled its potential due to inherently irreproducible surfaces used to enhance the Raman signals. If a robust and reliable surface was to be produced SERS could have applications in trace drug detection and catalytic reactions amongst others. Gold nanostructured void surfaces have been produced which yield full control over the enhancement, simply by tuning the surface to the correct layer wavelength. It was discovered that SER signals varied depending on the void size and film thickness, and that a 350 nm void structure gave rise to enhancements in Raman signals of the order 108, and the 600 nm structures have a reproducibility of <10% variation, in terms of signal, across a surface. the theory as to why the structures give rise to a strong enhancement comes from the fully controllable plasmon modes within the structures, which are based on molecular orbital fields. The strongest SER signal arose when the laser light and outgoing Raman band were encompassed within a P type of plasmon mode. The underlying background in every SERS spectra was also attributed to photoluminescence (PL) from the gold surface, and an excellent correlation between the PL and surface plasmons was observed. The detection of pyridine and carbon monoxide using in-situ electrochemical experiments have shown that the substrate has widened the (electrochemical) potential window for monitoring reactions, and show excellent promise as future chemical sensors.

APA, Harvard, Vancouver, ISO, and other styles

23

ESPOSITO, ALESSANDRO. "Sviluppo e caratterizzazione di substrati SERS label-free per analisi di biofluidi e applicazioni biomediche." Doctoral thesis, Università degli Studi di Trieste, 2022. http://hdl.handle.net/11368/3030740.

Full text

Abstract:

Surface Enhanced Raman spectroscopy is a powerful analytical technique, in which are combined high sensitivity and chemical species recognition, which are provided by the surface signal enhancement and the vibrational fingerprinting of the Raman spectroscopy, respectively. Thus, the inelastic scattering (or Raman scattering) of the light is used to capture so-called Raman active vibrations in presence of an external source of light. On the base of this phenomenon, unique vibration can allow identifying with high selectivity a tremendous number of chemical structures. But, Raman scattering is di per se a rare event, that occurs only when certain circumstances are achieved. In SERS spectroscopy coherent oscillating conductive electrons on the metal surface are used to amplify the vibrational energy by the production of a very confined electromagnetic field at the nanoscale, providing an outcome signal up to 10 times stronger than the initial one. We refer to this effect as localized surface plasmon resonance LSPR, which allows specific nanostructured surfaces to reach molecular resolution too. SERS is also a fast, user-friendly technique, in which these features coupled with the advancement in optic and photonics (bench, potable and palmar instrumentation can be bought nowadays) have created a fertile field for the spreading of SERS applications. Nevertheless, plasmonic surfaces, or more properly called SERS substrates, can be obtained with a simple procedure, e.g by coating on the paper silver nanoparticles, obtained with salt reduction in water. Eventually, SERS spectroscopy is a non-destructive technique allowing measurement in aqueous media. For all these features SERS has been introduced, as a promising tool in precision medicine and biofluid analysis. In this frame, the scope of my thesis has been to find a simple and inexpensive method to extract biochemical information from complex biological matrixes. The simplest way to do SERS biosensing is to use the Label-free SERS approach. Thus, it is possible, accordingly to the sample compositions and affinity for the metal surface, to identify small molecules and more specifically metabolites. This provides a snapshot of a pool of metabolites of which the variation can be used to extract information on the state of illness of patients. For instance, many studies of label-free SERS ha reached interesting results such as in monitoring the therapeutic window and in the classification of patients' state of illness on the base of the relative concentration of small metabolites. In this frame I have developed for my PhD project, a protocol to extract biochemical information from stool samples that were adopted to study for the first time stool samples of the celiac patient (celiac disease can be defined as an uncontrolled immunogenic response to the gluten ingestion), with promising results in assessing the compliance of gluten-free diet patient. On the other hand, we have developed a fast SERS sampling protocol for human serum on the paper that allow achieving reproducible SERS spectra via the centrifugation of few µl of samples spotted on the paper in the presence of silver colloidal Nanoparticles. Thus, it was possible to obtain a fast and reliable SERS protocol to be adopted for sampling and SERS bioanalytic.
La spettroscopia Raman Surface Enhanced è una potente tecnica analitica, in cui sono combinati l'elevata sensibilità e il riconoscimento delle specie chimiche, forniti rispettivamente dall'aumento del segnale di superficie e dal fingerprinting vibrazionale della spettroscopia Raman. Pertanto, lo scattering anelastico (o Raman scattering) della luce viene utilizzato per catturare le cosiddette vibrazioni attive Raman in presenza di una fonte di luce esterna. Sulla base di questo fenomeno, una vibrazione unica può consentire di identificare con elevata selettività un numero enorme di strutture chimiche. Ma la dispersione Raman è di per sé un evento raro, che si verifica solo quando si ottengono determinate circostanze. Nella spettroscopia SERS gli elettroni conduttivi oscillanti coerenti sulla superficie del metallo vengono utilizzati per amplificare l'energia vibrazionale mediante la produzione di un campo elettromagnetico molto confinato su scala nanometrica, fornendo un segnale di esito fino a 10 volte più forte di quello iniziale. Ci riferiamo a questo effetto come risonanza plasmonica di superficie localizzata LSPR, che consente a specifiche superfici nanostrutturate di raggiungere anche la risoluzione molecolare. SERS è anche una tecnica veloce e facile da usare, in cui queste caratteristiche, unite al progresso nell'ottica e nella fotonica (oggi è possibile acquistare strumentazione da banco, potabile e palmare) hanno creato un campo fertile per la diffusione delle applicazioni SERS. Tuttavia, superfici plasmoniche, o più propriamente dette substrati SERS, possono essere ottenute con una semplice procedura, ad esempio ricoprendo sulla carta nanoparticelle di argento, ottenute con riduzione di sale in acqua. Alla fine, la spettroscopia SERS è una tecnica non distruttiva che consente la misurazione in mezzi acquosi. Per tutte queste caratteristiche è stato introdotto SERS, come uno strumento promettente nella medicina di precisione e nell'analisi dei biofluidi. In questo contesto, lo scopo della mia tesi è stato quello di trovare un metodo semplice ed economico per estrarre informazioni biochimiche da matrici biologiche complesse.

APA, Harvard, Vancouver, ISO, and other styles

24

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

Full text

Abstract:

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

APA, Harvard, Vancouver, ISO, and other styles

25

ZALAFFI, MARIA SOLE. "Metal nanostructures decorated with silver nanostars: a novel highly efficient SERS substrate for dyes and pigments detection." Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2963765.

Full text

Abstract:

The detection of artistic molecules such as dyes and/or pictorial binders employed in the field of Cultural Heritage requires more and more sensitive techniques. The surface enhanced Raman spectroscopy (SERS) represents a valuable option due to its ability to reveal molecules adsorbed or bound onto nanostructured interfaces. In order to maximize the enhancement of the Raman effect, different Ag and Au nanomaterials where bound together to produce hierarchical structures. In particular, silver nanostars (AgNSs) were chosen because of the strong enhancement caused by their anisotropic shape and they were prepared by one-pot chemical synthesis [1]. The AgNSs were used to decorate two different gold nanostructures, namely Au nanowires (AuNWs) and sphere segment void (SSV) structured surfaces. The AuNWs were obtained in the shape of ensembles of nanoelectrodes by templated elecrtroless deposition in nanoporous membranes [2,3] while the SSV substrates were prepared via gold electrodeposition by using a monolayer of polystyrene spheres as template [4]. The enhancement of the Raman effect was tested at first through the employment of benzenethiol, a well known Raman probe. Thereafter, cochineal lake-pigment, in particular, was chosen as target owing to its use throughout the history of art. Lakes are complex coloring pigments in which an organic dye (e.g. cochineal, madder or kermes) is adsorbed onto solid particles of inorganic salts. This composite structure, composed by an organic molecule chelated by metallic ions, makes the Raman detection of lakes extremely challenging. However, the described issue is overcome by employing highly sensitive SERS substrates as those prepared in the context of this thesis. We compared the magnitude of the enhancements obtained with different SERS substrates: standing alone AgNSs, AuNWs ensembles and SSV substrates and hierarchical nanostructures composed by AgNSs combined to AuNWs (AgNSs@AuNWs) and to SSV substrates (AgNSs@SSV). Particularly strong enhancements were recorded in the case of the AgNSs@SSV substrates, showing the high potential of the so called particle-in-cavity (PIC) architectures [5]. Concluding, we synthesized highly effective hierarchical nanostructures whose future employment lies in the production of extremely sensitive SERS biosensors to be applied in the detection of artistic dyes and binders. References [1] García-Leis A., García-Ramos J. V., Sánchez-Cortés S., J. Phys. Chem. C, 2013, 117, 7791. [2] De Leo M., Kuhn A., Ugo P., Electroanal., 2007, 19 , 227. [3] Ugo P., Moretto L. M., Template Deposition of Metals, Ed. C. Zosky, Handbook of Electrochemistry, chapter 16.2, Elsevier, Amsterdam, NL, 2007, 678. [4] Mahajan S., Cole R. M., Soares B. F., Pelfrey S. H., Russell A. E., Baumberg J. J., Bartlett P. N., Phys. Chem. C, 2009, 113 (21), 9284. [5] Speed J. D., Johnson R. P., Hugall J. T., Lal N. N., Bartlett P. N., Baumberg J. J., Russell A. E., Chem. Commun., 2011, 47, 6335.

APA, Harvard, Vancouver, ISO, and other styles

26

Panarin, Andrei Yu. "Mise au point, étude et applications de matériaux poreux recouverts d'argent en tant que substrats SERS-actifs." Paris 6, 2010. http://www.theses.fr/2010PA066084.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Pacaud, Mathias. "Synthesis and physico-chemical evaluation of gold nanoflowers (AuNFs) as new substrates for bioanalytical SERS." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR3804.

Full text

Abstract:

Un immense intérêt est porté sur les nanostructures métalliques anisotropes d’or (AuNFs) qui s’explique par les propriétés uniques qu’elles procurent et qui peuvent servir dans divers domaines, notamment dans le biomédicale. On cherche à maitriser leurs propriétés optiques liées aux oscillations collectives d’électrons de surface appelées plasmons. Elles possèdent une bande de résonance plasmonique localisée de surface (LSPR, comme localized surface plasmon resonance) située dans le rouge - proche infrarouge (> 600 nm). Leur capacité d’interagir avec la lumière rouge - proche IR (fenêtre optique biologique) les rend intéressantes en tant qu’agent d’imagerie optique et opto-acoustique. Dans le cas particulier de la diffusion Raman exaltée de surface (SERS, comme surface-enhanced Raman scattering), les AuNFs sont capables de procurer les zones d’exaltation appelées « hot spots » dans les jonctions entre leurs pétales. Ainsi, on peut les utiliser comme substrat SERS sans avoir besoin de les agréger, à la différence des nanosphères d’or. Le protocole de synthèse des AuNFs que nous avons développé est rapide, en une seule étape et n’utilise qu’un nombre réduit de réactifs connus qui sont peu ou pas toxiques. De plus, notre protocole permet de contrôler les caractéristiques des AuNFs telles que leur taille et la position de leur bande LSPR, entre 600 et 900 nm. Afin de garantir une stabilité colloïdale dans des milieux divers, nous avons enrobé nos AuNFs avec des polymères biocompatibles (alginates, chitosan, Pluronics, PVP et PEG) ou les avons encapsulées dans une matrice de silice. Les substrats colloïdaux à base de ces AuNFs enrobées d’enveloppes biocompatibles ont ainsi montré leur potentiel pour procurer l’effet SERS sans agrégation et permettre l’analyse ultrasensible de petits chromophores (comme le Bleu de Nil). De plus, nos résultats montrent que ces nouveaux substrats sont capables de délivrer une charge de molécules dans des cellules cancéreuses. Ainsi, ils semblent prometteurs en tant qu’agents théranostiques, applicables non seulement en SERS, mais également en imagerie optique ou opto-acoustique et en thérapie
A huge attention is paid on anisotropic gold metal nanostructures (AuNFs) because of the unique properties they can provide in various fields, in particular the biomedical applications. We are trying to control their optical properties related to the collective oscillations of surface electrons called plasmons. They have a localized surface plasmon resonance band (LSPR) located in the red - near infrared (> 600 nm). Their ability to interact with red light - near IR (optical biological window) makes them interesting as optical and optoacoustic imaging agents. In the specific case of the surface-enhanced Raman scattering (SERS), AuNFs are able to provide enhancement zones called "hot spots" in the junctions between their petals. Thus, they can be used as SERS substrates without the need to be aggregated, unlike for gold nanospheres. The protocol to synthesize AuNFs that we developed is fast, in one-step and uses only a small number of known reagents that are low or non-toxic. In addition, our protocol allows us to tune the characteristics of the AuNFs such as their size and the position of their LSPR band, between 600 and 900 nm. In order to guarantee their colloidal stability in various media, we have coated our AuNFs with biocompatible polymers (alginates, chitosan, Pluronics, PVP and PEG) or encapsulated them in a silica matrix. Colloidal substrates based on these AuNFs coated with biocompatible envelopes have thus shown their potential to provide the SERS effect without aggregation and allow the ultra-sensitive analysis of small chromophores (such as Nile Blue). In addition, our results show that these new substrates are able to deliver a cargo of molecules to the cancer cells. Thus, they seem promising as theranostic agents, applicable not only in SERS, but also in optical or optoacoustic imaging and therapy

APA, Harvard, Vancouver, ISO, and other styles

28

Weber, Verena. "Plasmonic nanostructures for the realization of sensor based on surface enhanced Raman spectroscopy." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423838.

Full text

Abstract:

The field of Plasmonics deals with interaction processes between an electromagnetic radiation of appropriate wavelength and the conduction electrons of a metal. The induced collective oscillation of the electrons is called Plasmon Resonance. The Localized Surface Plasmon Resonance (LSPR) occur when the excitation involves surface electrons of nanostructures with dimensions less or comparable to the excitation wavelength. The excitation causes a strong enhancement of the local field around the metal nanostructure, which, combined with Raman Spectroscopy, could be very interesting for molecular sensing. The Raman technique is well known for providing a fingerprint spectrum of a given molecule, but has the great limitation of low sensibility. By adsorbing the analyte of interest on a plasmonic substrate in the region of enhanced local field, high detection sensitivity can be reached through Surface Enhanced Raman Spectroscopy (SERS). The first part of the present work is focused on the synthesis and characterization of gold and silver nanoparticles (Au and Ag NPs) and gold nanoshells (Au NSs) and their exploitation for the realization of SERS substrates, both in colloidal solutions and on solid supports. Different metal nanostructures give the possibility to exploit the LSPR in a wide spectral range, from the Vis to the near IR. Their optical and morphological characterization is carried out with conventional techniques, like TEM, AFM, UV-Vis absorption and Surface Enhanced Raman Spectroscopy, and with a new characterization technique, rarely used in this research field: the Photoacoustic Spectroscopy. It provides information about the absorption contribution to the total extinction of a plasmonic nanostructure. From a rigorous measurement of the SERS enhancement factor and from Photoacoustic Spectroscopy data at different excitation wavelengths, some considerations could be done concerning the relation of far field extinction and near field SERS properties. SERS EF profile measurements on liquid and solid SERS substrates demonstrated the presence of hot spots. The solid SERS substrates were chemically stable, homogeneous and reproducible and showed EF values of about 104-105. In colloidal solution, the EF values were about 103-106, depending on the metal nanostructure. Photoacoustic measurements performed on Au NSs in solution were in agreement with theoretical predictions found in literature. In the second part of the work, the plasmonic substrates, realized with Au NPs and Au NSs, were used for the realization of label free SERS sensors, to detect toxic aromatic chemical species and biological molecules. A sensor for toxic volatile compounds, based on Au NPs and Au NSs substrates coupled with a porous organic-inorganic hybrid sol-gel matrix, was realized. The matrix was specifically chosen for exhibiting a high-affinity interaction to aromatic hydrocarbons. The enhancement activity of the Au NPs and Au NSs substrates on the sol gel matrix alone was demonstrated. Some problems in the xylene detection process through SERS were probably due to the fast matrix regeneration under the laser radiation. Although, the enhanced SERS efficiency due to the detection design was demonstrated. Another application was based on the development of a novel label-receptor system, based on the cromophore 4-hydroxyazobenzene-2 carboxylic acid (HABA) and its specific antibody, to be used in bio-analytical applications. The interesting behaviour of the HABA dye relies in changing its tautomeric structure from an azo to a hydrazo form, thanks to the interaction with its antibody. This structural change can be exploited for SERS detection of the label-receptor interaction. Properly synthesized and characterized HABA derivatives were adsorbed onto SERS substrates, further incubated in the antibody solution. The HABA signals were well visible on both Au NSs and Au NPs substrates. No HABA change could be detected through SERS, because the antibodies extracted in vivo from two rabbits, do not cause the quantitative change of the HABA structure.
La Plasmonica si occupa dell’interazione di una radiazione elettromagnetica di opportuna lunghezza d’onda con gli elettroni di conduzione di un metallo. L’oscillazione collettiva degli elettroni, indotta da questa interazione, è chiamata appunto Risonanza Plasmonica. La risonanza plasmonica di superficie localizzata avviene quando gli elettroni coinvolti sono quelli di superficie di un metallo nanostrutturato con dimensioni minori o comparabili alla lunghezza d’onda di eccitazione. Da questa eccitazione deriva una forte amplificazione del campo elettromagnetico locale, localizzato nelle immediate vicinanze della nanostruttura metallica. Tale amplificazione, unita a una tecnica di rivelazione spettroscopica specifica, quale la spettroscopia Raman, può essere sfruttata per la realizzazione di sensori molecolari. La tecnica Raman è conosciuta come altamente specifica, perché in grado di fornire uno spettro caratteristico della singola molecola, identificandone univocamente la presenza e la costituzione. La sua maggiore limitazione, però, è la bassa sensibilità. Ponendo l’analita in prossimità di un substrato plasmonico, proprio nella regione di forte amplificazione del campo locale, la sensibilità di rivelazione viene fortemente aumentata, dando origine alla spettroscopia Raman amplificata da superfici (SERS). La prima parte del presente lavoro è focalizzata sulla sintesi e sulla caratterizzazione di nanoparticelle d’argento, d’oro e di nano gusci d’oro (chiamati nanoshell) e sul loro impiego per la realizzazione di substrati SERS, sia in soluzione colloidale che su substrato solido. L’utilizzo di differenti nanostrutture metalliche, dà la possibilità di sfruttare la risonanza plasmonica localizzata di superficie in un’ampia regione spettrale, che si estende dal visibile al vicino infrarosso. La caratterizzazione ottica e morfologica delle nanostrutture è stata effettuata con tecniche convenzionali, come la spettroscopia di assorbimento UV-visibile, il SERS, la microscopia elettronica a trasmissione e la microscopia a forza atomica. Ad esse è stata affiancata anche una tecnica raramente usata nell’ambito della plasmonica: la spettroscopia fotoacustica. Questa può fornire informazioni riguardanti il contributo di assorbimento, all’estinzione totale, di una nanostruttura plasmonica. Da una rigorosa misura dei fattori di amplificazione e delle proprietà di fotoacustica al variare della lunghezza d’onda, possono essere fatte alcune considerazioni riguardanti la possibile relazione tra l’estinzione (proprietà di campo lontano) e l’ amplificazione SERS (proprietà di campo vicino). Le misure dei profili di eccitazione SERS su substrati plasmonici in liquido e su supporto solido, hanno evidenziato la presenza di hot spots, ovvero di zone fortemente amplificate dall’interazione di due o più nanostrutture. I substrati SERS solidi sono risultati chimicamente stabili, omogenei e riproducibili; essi presentano valori di fattori di amplificazione attorno a 104-105. In soluzione colloidale, i fattori di amplificazione delle nanostrutture hanno raggiunto valori nell’intervallo 103-106, dipendentemente dal tipo di nanostruttura metallica investigata. Le misure di fotoacustica effettuate su soluzioni colloidali di nanoshell d’oro si sono rivelate in accordo con le predizioni teoriche di letteratura. Nella seconda parte del lavoro, i substrati plasmonici, realizzati principalmente con nanoparticelle e nanoshell d’oro, sono stati impiegati per la realizzazione di sensori SERS per la rivelazione di specie chimiche e biologiche. É stato realizzato un sensore di composti tossici aromatici volatili, accoppiando un substrato plasmonico con un film poroso di sol gel ibrido organico-inorganico. La componente organica della matrice sol gel è stata appositamente scelta per la sua alta affinità a composti aromatici, quali lo Xilene. È stata dimostrata l’amplificazione dei segnali della matrice da parte della componente plasmonica, ma si sono riscontrati alcuni problemi nella rivelazione delle molecole di analita attraverso il SERS. La difficoltà nella rivelazione è probabilmente dovuta al veloce deadsorbimento dello Xilene dalla matrice a causa del forte riscaldamento locale causato dalla radiazione laser. Nonostante questo, si è comunque dimostrata l’aumentata efficienza del sensore progettato, rispetto ai suoi componenti singoli. La seconda applicazione studiata ha riguardato la realizzazione di un sistema analita-accettore innovativo, che può essere utilizzato per diverse applicazioni bioanalitiche; esso è basato sull’interazione tra un cromoforo diazobenzenico (HABA) e il suo anticorpo specifico. Alla base dell’applicazione si trova una proprietà interessante del suddetto cromoforo, che è quella di cambiare la sua struttura molecolare, passando da una forma azo alla forma idrazo, dopo aver interagito con il suo anticorpo specifico. Questa variazione nella struttura molecolare può essere sfruttata per la rivelazione dell’avvenuta interazione analita-accettore, mediante SERS. Alcuni derivati di questo cromoforo sono stati sintetizzati e caratterizzati in modo da poter essere adsorbiti su un substrato SERS, che viene successivamente incubato in una soluzione di anticorpo. I segnali SERS della molecola di HABA sono risultati ben visibili sia sui substrati di nanoparticelle che di nanoshell d’oro. Purtroppo non è stato possibile rivelare la variazione strutturale del cromoforo, in quanto gli anticorpi, estratti in vivo da due coniglietti, inducono solo un parziale cambio di struttura, rendendo la rivelazione SERS alquanto difficile.

APA, Harvard, Vancouver, ISO, and other styles

29

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

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Gorunmez, Zohre. "Finite-Difference Time-Domain (FDTD) Modeling of Nanoscale Plasmonic Substrates for Surface-Enhanced Raman Spectroscopy (SERS)." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563296001850111.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Pierre-Bolivar, Marie Carmelle Serviane. "Synthesis and characterization of perm-selective SERS-active silica-coated gold nanospheres for the direct detection of small molecules." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/5042.

Full text

Abstract:

Noble metal nanomaterials have numerous uses in plasmonic and surface enhanced Raman scattering (SERS) detection applications; however, upon the addition of analytes, nanomaterials often undergo uncontrolled aggregation which leads to inconsistent signal intensities. To overcome this limitation, the effect of gold nanosphere concentration, column purification, and surface chemistry functionalization using internally etched silica stabilization methods was investigated on SERS assays for small molecule detection. Nanostructure composition, size, shape, stability, surface chemistry, optical properties, and SERS-activity were monitored using localized surface plasmon resonance (LSPR or extinction) spectroscopy, transmission electron microscopy (TEM), and Raman spectroscopy. First, the behavior of citrate-stabilized gold nanospheres was monitored as a function of molecular surface coverage. Both extinction and SERS spectral intensities increased linearly below monolayer functionalization. Above this value, however, uncontrolled nanoparticle aggregation occurred and large but irreproducible SERS signal intensities were monitored. Next, gold nanoparticles were encapsulated with varying silica shell thicknesses and purified using traditional centrifugation steps and/or column chromatography. Relative to the traditionally purified (i.e. centrifuged) samples, the SERS responses from small molecules using the column purified nanoparticle samples followed a well-known SERS distance-dependence model. Thus, surface chemistry cannot form more than a 2 nm thick layer on gold nanospheres if SERS applications were targeted. To overcome these challenges, gold nanospheres encapsulated with a thick silica shell were made SERS-active by etching the internal silica layer near the metal surface. During the synthesis of these internally etched silica-coated gold nanospheres, the LSPR wavelength shift, a parameter related to the effective local refractive index near the gold core, was monitored instead of etching time, in order to produce nanostructures with more uniform internal silica etching from sample to sample. The SERS-activity of a target molecule using these nanostructures was measured as a function of LSPR wavelength shift. SERS signal intensity increased, which suggested that more analyte molecules were able to bind to the gold surface because of the larger pore size in the silica layer near the metal core. Further exploration of these findings should increase the integration of solution-phase nanoparticles in more predictable functions in future applications, resulting in more quantitative and reproducible molecular detection in complex sample matrices, including biological and environmental samples.

APA, Harvard, Vancouver, ISO, and other styles

32

Lima, Leandro Holanda Fernandes de. "Síntese e caracterização de compósitos de nanotubos de carbono e nanopartículas de prata e sua aplicação como substrato SERS." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-22102013-102146/.

Full text

Abstract:

Neste trabalho foram produzidos compósitos de nanotubos de carbono contendo nanopartículas de prata, os quais foram testados como substratos SERS (Surface-enhanced Raman Spectroscopy) na detecção do cristal violeta. Para obter tais compósitos foram necessárias modificações de nanotubos de carbono através de funcionalizações químicas para inserção de grupos carboxila e tiol, capazes de interferir no crescimento de nanopartículas metálicas através de um processo de redução térmica do acetato de prata sobre a superfície das amostras de nanotubo. Para a preparação de tais compósitos foram utilizadas duas amostras de nanotubos, uma de parede simples (SWNT) e outra de paredes múltiplas (MWNT) a fim de avaliar diferenças nos tamanhos e homogeneidade das nanopartículas formadas. Utilizou-se como ferramenta investigativa a espectroscopia Raman na caracterização destes compósitos, que forneceu informações sobre interação dos nanotubos de carbono com as nanopartículas de prata e mudanças estruturais ocasionadas durante a gama de funcionalizações. Para avaliar a morfologia dos compósitos foi utilizada a microscopia eletrônica de varredura (MEV) e a microscopia eletrônica de transmissão (TEM) que forneceram informações sobre o tamanho e a disposição das nanopartículas formadas através do tratamento térmico dos nanotubos com acetato de prata. Os compósitos preparados foram aplicados como substrato SERS na detecção do cristal violeta. Nesta aplicação foi avaliada a capacidade dos nanotubos em adsorver estas moléculas e o potencial do substrato na intensificação do espectro Raman do analito. Observou-se que a adsorção do cristal violeta sobre uma amostra de SWNT foi máxima após o tempo de 60 minutos de agitação. Já o substrato utilizado (SWNT-COOH@Ag) permitiu a detecção do cristal violeta em solução aquosa com concentração de até 1,0.10-8 mol.L-1. Utilizando o mapeamento Raman foi possível avaliar a presença do analito através do monitoramento de uma banda do espectro vibracional do analito intensificada pelo efeito SERS
In this work, we produced carbon nanotube composites containing silver nanoparticles, which were tested as SERS (Surface-enhanced Raman Spectroscopy) substrates in the detection of crystal violet. For these the synthesis of these composites modifications of the carbon nanotubes surface through chemical functionalizations were necessary for insertion of carboxyl and thiol groups, that can affect the growth of metal nanoparticles in thermal reduction process of silver acetate on the surface of the nanotube samples. For the preparation of such composites have single walled carbon nanotubes (SWNT) and a multi-walled carbon nanotubes (MWNT) to evaluate differences in size and homogeneity of the nanoparticles formed. Raman spectroscopy was used as an investigative tool in the characterization of these composites, which provided information on the interaction of carbon nanotubes with silver nanoparticles and structural changes ocurring during the range of functionalizations. To evaluate the morphology of the composites scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used. These techniques provided information about the size and assembly of the silver nanoparticles formed by heat treatment of the nanotubes with silver acetate. The nanotubes@Ag composites were applied as SERS substrates in the detection of crystal violet. In this application, we evaluated the ability of nanotubes to adsorb these molecules and the substrate potential in enhancing the Raman spectrum of the analyte. It was observed that the adsorption of the crystal violet on a sample of SWNT was maximal after 60 minutes of stirring. Substrate used (SWNT-COOH @ Ag) allowed detection of crystal violet in aqueous solution with a concentration as low as 1,0.10-8 mol.L-1. Using Raman mapping was possible to evaluate the presence of the analyte by monitoring a band of vibrational spectrum of the analyte enhanced by SERS effect.

APA, Harvard, Vancouver, ISO, and other styles

33

Habouti, Salah [Verfasser]. "Herstellung substratgestützter, nanoporöser Aluminiumoxid-Template und ihre Anwendung für die Präparation von hocheffizienten SERS-Substraten / Salah Habouti." Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1065232918/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

DALLA, MARTA SILVIA. "Development of nanostructured substrates for quantification of anticancer drugs in biofluids with Surface Enhanced Raman Scattering (SERS)." Doctoral thesis, Università degli Studi di Trieste, 2017. http://hdl.handle.net/11368/2908137.

Full text

Abstract:

To date, therapeutic drug monitoring (TDM), that is the quantification of anticancer drugs in biofluids of oncological patients, is expensive and time consuming. Such a quantitative determination is crucial for a successful chemotherapic treatment due to the high interpatient variability of the anticancer drugs levels in biofluids. A frequent TDM turns out to be necessary to limit as far as possible the heavy side-effects of the treatment. Thus, the development of a new Point Of Care (POC) tool for a faster and less expensive TDM is highly desirable. Surface Enhanced Raman Scattering (SERS) is a surface-sensitive technique able to detect low concentrations of specific analytes in liquid environments. The high sensitivity given by metal nanostructured materials, the specificity given by Raman spectroscopy, the rapidity of the measurements and the possibility to develop inexpensive solid SERS substrates point to SERS as an appropriate platform for TDM. Moreover, solid SERS substrates together with the availability of portable instruments make this technique a possible new POC tool to quantify the drugs were a quick response is needed. The aim of this doctoral project is the development and the optimization of cost-efficient, repeatable and sensitive solid SERS substrates for quantitative analysis of antitumoral drugs in biofluids such as human serum. In the first part of this doctoral thesis, a general introduction about Raman spectroscopy, SERS and SERS as quantitative technique will be reported. In the second chapter, the development and the optimization of repeatable solid SERS substrates constituted by metal nanoparticles deposited on filter paper with a simple dipping method, it will be presented. Specifically, four kinds of substrates developed with dip-coating method will be presented, differing depending on the type of nanoparticles used. As the first step, I performed a systematic study on c-Au and c-Ag paper made substrates using two different non resonant analytes as probe molecules (i.e. Adenine and 4-Mercaptobenzoic acid). The aim was to optimize the parameters involved in the development procedure (i.e. the kind of filter paper, the NPs concentration and the presence of an aggregating agent) exploring how they affect the repeatability of the substrates. Optimized paper-based SERS substrates aiming at building a platform for quantitative analysis will be presented in terms of inter- and intra- sample repeatability, sensitivity and long term stability. Then, solid substrates based on different nanoparticles, namely h-Ag and NSs, will be presented and discussed from a repeatability point of view. The SERS signal variation, hence the repeatability, will be quantified calculating the relative standard deviation (RSD%). In the third part of the work, I will present some applications of the substrates developed in the first part. In particular, preliminary results will be reported, which are related to Methotrexate (MTX) and Imatinib (IMT) rapid quantification, in model solutions mimicking biofluids as well as in real biofluids such as human serum. Optimized c-Au and h-Ag paper-made substrates were used for the analysis of MTX and IMT, respectively. The direct quantification of MTX and IMT spiked in human serum will be presented by means of combined SERS with paper-made solid substrates and a multivariate Partial Least Squares Regression (PLSR) model. The model performance will be judged on the basis of the Root Mean Square Error of Prediction (RMSEP), which quantifies the quantification accuracy and precision.

APA, Harvard, Vancouver, ISO, and other styles

35

Mareš, Petr. "Depozice Ga a GaN nanostruktur na křemíkový a grafenový substrát." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231443.

Full text

Abstract:

Presented thesis is focused on the study of properties of Ga and GaN nanostructures on graphene. In the theoretical part of the thesis a problematics of graphene and GaN fabrication is discussed with a focus on the relation of Ga and GaN to graphene. The experimental part of the thesis deals with the depositions of Ga on transferred CVD-graphene on SiO2. The samples are analyzed by various methods (XPS, AFM, SEM, Raman spectroscopy, EDX). The properties of Ga on graphene are discussed with a focus on the surface enhanced Raman scattering effect. Furthermore, a deposition of Ga on exfoliated graphene and on graphene on a copper foil is described. GaN is fabricated by nitridation of the Ga structures on graphene. This process is illustrated by the XPS measurements of a distinct Ga peak and the graphene valence band during the process of nitridation.

APA, Harvard, Vancouver, ISO, and other styles

36

Letourneau, Guillaume. "Mouvements de sels en substrats organiques pour la culture de la tomate de serre." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26776/26776.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Létourneau, Guillaume. "Mouvements de sels en substrats organiques pour la culture de la tomate de serre." Master's thesis, Université Laval, 2010. http://hdl.handle.net/20.500.11794/22399.

Full text

Abstract:

L'utilisation de substrats composés de sous produits peut être envisagée par les producteurs serricoles pour diminuer leurs impacts environnementaux et favoriser un développement durable de l'industrie. Pour la culture de la tomate, des mélanges de sciures et de tourbe ont démontré leur potentiel, mais ces substrats sont sujets à une accumulation problématique de sels en cours de culture. Cette étude vise l'obtention d'une meilleure compréhension des phénomènes liés aux mouvements de sels dans les substrats de culture. Un essai de culture en serre de la tomate a été réalisé pour effectuer un suivi de la salinité dans différents substrats et des expériences de lessivage en laboratoire ont été faits pour déterminer la proportion d'eau immobile qu'ils contiennent. Sans que les rendements n'en soient affectés, des salinités élevées et une proportion d'eau immobile importante liée à la présence de substances humiques ont été observées dans des mélanges de sciures et tourbe.

APA, Harvard, Vancouver, ISO, and other styles

38

Alam, Md Khorshed. "Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest." Thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101573.

Full text

Abstract:

This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest. Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls. The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively.

APA, Harvard, Vancouver, ISO, and other styles

39

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

Full text

Abstract:

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

APA, Harvard, Vancouver, ISO, and other styles

40

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

Full text

Abstract:

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, 2015.
Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-05-06T15:01:10Z No. of bitstreams: 1 2015_KarolyneVileladeOliveira.pdf: 4124843 bytes, checksum: a896d190db2a100ab397386387efb480 (MD5)
Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-05-23T18:18:59Z (GMT) No. of bitstreams: 1 2015_KarolyneVileladeOliveira.pdf: 4124843 bytes, checksum: a896d190db2a100ab397386387efb480 (MD5)
Made available in DSpace on 2016-05-23T18:18:59Z (GMT). No. of bitstreams: 1 2015_KarolyneVileladeOliveira.pdf: 4124843 bytes, checksum: a896d190db2a100ab397386387efb480 (MD5)
Neste trabalho foram preparados dois substratos com atividade SERS (surface-enhanced Raman scattering), baseados na dispersão de nanopartículas de prata em solução aquosa (AgNPs/Coloide) e em gel de agarose (AgNPs/Agar). Esses substratos foram caracterizados por MET e espectroscopia UV-vis. Ambos os substratos foram também investigados pelo efeito SERS, registrando-se 100 espectros em triplicata empregando o modo de mapeamento Raman numa região de 20x20 µm. Os diâmetros médios das AgNPs nas amostras de AgNPs/Coloide e AgNPs/Agar foram de 8 nm e 19 nm, respectivamente. Os espectros UV-vis desses materiais revelam que as AgNPs/Agar apresentam ressonâncias de plasmon de superfície na região de 600 nm. A adsorção da rodamina 6G (R6G) foi investigada para ambos os substratos, para concentrações entre 10-8 M e 10-5 M, por excitação SERS em 632,8 nm. As intensidades SERS da R6G nas AgNPs/Agar foram ca. 10 vezes mais fortes que aquelas apresentadas para a R6G adsorvida nas AgNPs/Coloide. As isotermas de adsorção obtidas para ambos os substratos foram bem ajustadas a isotermas de Langmuir com constantes de adsorção e energias livres de Gibbs de adsorção semelhantes, características de adsorção química. As AgNPs/Agar também foram investigadas como um substrato SERS-ativo para a adsorção de azul de metileno (MB), cristal violeta (CV) e benzotriazolato (BTA). Os resultados SERRS para o MB mostraram sinais de monômeros e dímeros de MB. Os resultados também mostraram que R6G e CV adsorvem na superfície das AgNPs/Agar formando pares iônicos com os íons cloreto adsorvidos usados para promover agregação, enquanto que o MB e BTA adsorvem quimicamente na superfície das AgNPs formando ligações Ag-N. Curvas de intensidade SERS vs. concentração do adsorbato em solução foram usadas para obter isotermas de adsorção. Em todos os sistemas investigados os dados experimentais apresentaram razoável ajuste para isotermas de Langmuir com constante de adsorção e energia livre de Gibbs de adsorção compatível com adsorção química (< -30 kJ.mol-1). Os resultados (SERS/SERRS) para R6G, MB e CV, em concentração de 10-8 M, adsorvidos em AgNPs/Agar mostraram que os sinais SERS/SERRS de moléculas únicas desses adsorbatos foram observados, mostrando que o material AgNPs/Agar obtido é um substrato adequado para a investigação SERS de adsorbatos em concentrações muito baixas.
Two different SERS (surface-enhanced Raman scattering) substrates have been prepared based on silver nanoparticles (AgNPs) dispersed in water solution (AgNPs/Colloid) and in agarose gel (AgNPs/Agar). The materials were characterized by TEM and UV-vis spectroscopy. Both substrates were also investigated by SERS by recording 100 spectra in triplicates, using the Raman mapping procedure in an area of 20x20 µm. The mean diameters of the AgNPs in these substrates were 8 nm and 19 nm, respectively. The UV-vis spectra of these materials show that the AgNPs/Agar present AgNPs aggregates with surface plasmon resonances in the region of 600 nm. The adsorption of Rhodamine 6G (R6G) at concentrations ranging from 10-8 M to 10-5 M on both substrates was investigated by SERS excitation at 632.8 nm. The SERS intensities of R6G on the AgNPs/Agar were ca. 10 times stronger than those displayed for R6G adsorbed on the AgNPs/Colloid. Adsorption isotherms obtained for both substrates were well fitted to Langmuir isotherms with similar adsorption constants and free Gibbs adsorption energy, characteristic of chemical adsorption. The AgNPs/Agar was further investigated as a SERS-active substrate for the adsorption of Methylene Blue (MB), Crystal Violet (CV) and benzotriazolate (BTA). The SERRS results for MB have shown signals from MB monomers and dimers. The results have also shown that R6G and CV adsorb on the AgNPs/Agar surface forming ion-pairs with the adsorbed chloride ions used to promote the AgNPs aggregation, while MB and BTA adsorb chemically on the AgNPs surface forming Ag-N bonds. Curves of SERS intensity vsadsorbate concentration in solution were used to obtain adsorption isotherms. In all investigated systems the experimental data presented reasonable fitting to Langmuir isotherm with adsorption constants and free Gibbs adsorption energy compatible with chemical adsorption (< -30 kJ.mol-1). The results (SERS/SERRS) for R6G, MB and CV at 10-8 M concentration adsorbed on AgNPs/Agar have shown that SERS/SERRS signals from single molecules of these adsorbates were observed, showing that the AgNPs/Agar material obtained is a suitable substrate for SERS investigation of adsorbates at very low concentrations.

APA, Harvard, Vancouver, ISO, and other styles

41

Sant\'Ana, Antonio Carlos. "Caracterização do ácido esquárico e materiais derivados por espectrocopia Raman intensificada (uso de substratos metálicos SERS de alto desempenho)." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-28112006-141248/.

Full text

Abstract:

Nesta tese foram utilizadas as espectroscopias de espalhamento Raman intensificado pela superficie(Surface-EnhancedRaman Scattering- SERS) e Raman ressonante para monitorar a adsorção e o comportamento faradáico do ácido esquárico e seus derivados, além de um sal de transferência de carga de esquarato e tetratiofulvaleno e dois copolímeros de esquarato e pirróis. Outro tema desenvolvido neste estudo foi a construção de substratos SERS-ativos de elevado desempenho. A técnica SERS tem sido campo de grande interesse desde a detecção do espectro aman de uma única molécula, em 1997.O desenvolvimento de substratos SERS-ativos de elevado desempenho depende da apropriada manipulação de superficies metálicas nanoestruturadas, o que nos levou a adquirir conhecimento na síntese destes substratos. Colóides e filmes de Ag e Au foram preparados e seu desempenho SERS comparado com a superficie de eletrodos ativados por ciclos de oxidação-redução. A intensificação obtida para esses filmes foi comparávelà observada em eletrodos. O ânion esquarato, produto da dupla desprotonação do ácido esquárico, apresenta substancial delocalização de carga, sendo amplamente usado na síntese de materiais orgânicos condutores. Foram realizadas as caracterizações vibracionais do ácido esquárico, hidrogeno-esquarato e esquarato, além de seu radical, através da técnica SERS. Baseado nos resultados experimentais, um mecanismo de adsorção destas espécies sobre eletrodos de Au e filmes de ilhas de Ag ou Au foi proposto. Os resultados SERS também mostram que o ácido esquárico adsorvido sobre Au é decomposto em um processo catalisado pela superficie metálica, emboraestas espécies sejam muito estáveis em solução. Baseado nos resultados SERS do tetratiofulvaleno e de suas espécies oxidadas, foi eletroquimicamente, e formado pelo radical-cátion tetratiofulvaleno e o radical-ânion esquarato. Os elevados fatores de intensificação de Raman ressonante e SERS do tetratiofulvaleno impediram a detecção do esquarato no sal de transferência de carga. Duas poliesquaraínas polí(1-metilpirrol-co-ácido esquárico) e poli(1-dodecilpirrol-coácido esquárico) foram sintetizadas e caracterizadas pelas espectroscopias Raman ressonante, SERS e ressonância paramagnética de spin (EPR). Estes resultados nos levaram a propor uma estrutura polimérica diferente da apresentada pela literatura. Nossos resultados mostraram a presença de um radical orgânico delocalizado, do ânion esquarato protonadoe de dicátions similares aos presentes no polipirrol.
In this Thesis Surface-Enhanced Raman Scattering (SERS) and resonance Raman spectroscopy were used for monitoring the adsorption and faradaic behavior of squaric acid and its derived species. In addition, the charge transfer salt of squarate and tetrathiofulvalene and the copolymers of squarate and pyrroles were also studied. Another theme developed in this study was the manufacturing of. high performance SERS-active substrates. SERS technique has been a field of great interest since the detection of a single molecule Raman spectrum in 1997. The development of high perforrnance SERS-active substrates depends on the proper manipulation of nanostructured metal surfaces, and order to acquire know-how in the synthesis of such substrates. Ag and Au island films as well as colloid substrates were prepared and compared with electrode surfaces SERS activated by oxidation-reduction cycles. The enhancement factor obtained for such films is comparable to those observed in electrodes. The squarate anion, product of the double deprotonation of squaric acid, shows substantial charge delocalization, being largely used in the synthesis of conducting organic materiaIs. The vibrational characterization of squaric acid, hydrogen-squarate, squarate as well as its radical was carried out from the SERS data. Based on the experimental data an adsorption mechanism of such species on Au electrodes and Au or Ag islands was proposed. SERS results also show that squaric acid adsorbed on Au is decomposed in a process catalyzed by the metal surface, although in solution it proves to be a very stable specles. The vibrational characterization of an electrochemically forrned charge transfer salt between tetrathiofulvalene radical-cation and squarate radical-anion was done based on the SERS data of tetrathiofulvalene and its oxidation species. The large resonance Raman and SERS enhancement factors of tetrathiofulvalene preclude the detection of the squarate species in the charge transfer salt. Two polysquaraines: poly(1-methylpyrrole-co-squaric acid) and poly(1-dodecylpyrrole-co-squaric acid) were synthesized and characterized by resonance Raman, SERS and Electron Paramagnetic Resonance Spectroscopy (EPR) techniques. The results lead us to propose a polymeric structure different from that present in the literature. Our data showed a delocalized organic radical in the polymeric matrices together with dications similar to those present in polypirrole and protonated squarate anion.

APA, Harvard, Vancouver, ISO, and other styles

42

Prokopec, V., J. Čejková, M. Singh, P. Matějka, and F. Štěpánek. "Use of Vibrational Spectroscopic Techniques for the Characterization of Structured Particles for Chemical Robots." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35158.

Full text

Abstract:

This work is aimed at utilization of vibrational spectroscopic techniques for characterization of several types of structural particles suitable for the construction of chemical robots. Several case studies are presented and discussed: (i) PNIPAM-coated silica particles, (ii) surface-functionalized magnetic nanoparticles modified by citric and oleic acid, (iii) nanocomposit SERS-active substrates consisting of self-assembled monolayers of linear α,ω-aliphatic diammines with different lengths on Ag metal surface and a flat Ag electrode followed by testing of sensing activity of AD/NPs systems in the detection of the pesticide aldrin. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35158

APA, Harvard, Vancouver, ISO, and other styles

43

Bárdy, Stanislav. "Depozice Ga a GaN nanostruktur na vodíkem modifikovaný grafenový substrát." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254312.

Full text

Abstract:

In this work we studied gallium on graphene. Depositions were done by Molecular beam epitaxy. We observed Raman enhancement and peak shifts by individual Ga islands. Simulation confirmed our assumption, that the enhancement is based on plasmonics effect that is also the main contribution of Surface-enhanced Raman spectroscopy. Another result is hydrogenation of graphene before deposition does have an effect on Ga structure and reduces diffusion length of Ga atoms.

APA, Harvard, Vancouver, ISO, and other styles

44

Combs, Zachary Allen. "Advanced substrate design for label-free detection of trace organic and biological molecules." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50314.

Full text

Abstract:

To truly realize and exploit the extremely powerful information given from surface-enhanced Raman scattering (SERS) spectroscopy, it is critical to develop an understanding of how to design highly sensitive and selective substrates, produce specific and label-free spectra of target analytes, and fabricate long-lasting and in-the-field ready platforms for trace detection applications. The study presented in this dissertation investigated the application of two- and three-dimensional substrates composed of highly-ordered metal nanostructures. These systems were designed to specifically detect target analytes that would enable the trace, label-free, and real-time detection of chemicals and biomolecules. Specifically, this work provides new insight into the required properties for maximizing electromagnetic and chemical Raman enhancement in three-dimensional porous alumina substrates by designing metal nanostructure shape, density, aggregated state, and most importantly aligning the substrate pore size with the excitation wavelength used for plasmonic enhancement leading to the ppb detection of vapor phase hazardous chemicals. A new micropatterned silver nanoparticle substrate fabricated via soft lithography with specific functionalization was developed, which allows the simultaneous analyte and background detection for trace concentrations of the target biomolecule, immunoglobulin G. Also, a novel functionalized SERS hot spot fabrication technique, which utilizes highly specific aptamers as both the mediator for electrostatic assembly of gold nanoframe dimers as well as the biorecognition element for the target, riboflavin, to properly locate the tethered biomolecule within the enhanced region for trace detection, was demonstrated. We suggest that the understanding of SERS phenomena that occur at the interface of nanostructures and target molecules combined with the active functionalization and organization of metal nanostructures and trace detection of analytes discussed in this study can provide important insight for addressing some of the challenges facing the field of SERS sensor design such as high sensitivity and selectivity, reliable and repeatable label-free identification of spectral peaks, and the well-controlled assembly of functional metal nanostructures. This research will have a direct impact on the future application of SERS sensors for the trace detection of target species in chemical, environmental, and biomedical fields through the development of specific design criteria and fabrication processes.

APA, Harvard, Vancouver, ISO, and other styles

45

BERNARD, AGNES. "Mise au point de substrats actifs en sers (surface-enhanced raman spectroscopy) et application a l'analyse de traces de polluants en milieux aqueux." Paris, Institut national d'agronomie de Paris Grignon, 1997. http://www.theses.fr/1997INAP0019.

Full text

Abstract:

En vue d'evaluer l'impact des produits chimiques sur l'environnement aquatique, l'industrie chimique cherche a developper des methodes analytiques lui permettant de controler rapidement la concentration de ces produits en solution aqueuse a l'etat de traces. Les techniques analytiques ne sont que rarement applicables directement aux solutions aqueuses. Pour cela, nous avons envisage l'utilisation de la spectrometrie de diffusion raman. Cette technique etant peu sensible, nous nous sommes interesses a l'effet surface-enhanced raman spectroscopy, phenomene qui permet d'amplifier le signal raman diffuse d'une molecule adsorbee sur une surface metallisee d'un facteur 10#6 a 10#8. Dans un premier temps, nous avons etudie les aspects theoriques et qualitatifs de cette methode. Il en ressort que l'effet sers depend grandement de l'etat morphologique de la surface des substrats ainsi que des parametres experimentaux intervenant au cours de l'analyse. Nous nous sommes alors interesses a deux familles de substrats : des systemes en solution et des substrats a l'etat solide. Les premiers presentent de nombreux avantages car ils sont faciles a preparer et a utiliser, la taille des particules peut etre controlee et ils sont caracterises facilement et rapidement. Neanmoins ils sont instables en presence de composes capables de s'adsorber sur le metal. Nous avons montre que l'addition d'une solutin de poly(ethylene glycol) stabilise suffisamment les complexes collide-analyte, mais qu'il est necessaire de determiner le taux de polymere adapte a chaque nouveau produit. Enfin, parmi les differentes formes de substrats solides, les monocouches de colloides immobilises sur des plaques de chromatographie en couche mince dont la silice a ete modifiee chimiquement, semble constituer le substrat le mieux adapte a notre objectif. Nous sommes ainsi parvenus a detecter des traces de chlorure de methacryloxyethyltrimethyl ammonium jusqu'a une concentration de 10 ppm, et ceci de facon systematique.

APA, Harvard, Vancouver, ISO, and other styles

46

Hong, Seongmin. "Optimization, Modification and Application of Gold Nanoparticles as the Substrates of Surface Enhanced Raman Spectroscopy." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4819.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Huang, Wen-Chi, and 黃文岐. "Study of recyclable SERS substrates." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/838v2z.

Full text

Abstract:

碩士
國立臺灣科技大學
材料科學與工程系
107
This study attempted to develop recyclable and reusable SERS samples, and prepared separately powder type samples and substrate type samples for discussion. 　　The first part is to prepare a powder sample with a magnetic and SERS composite structure. Iron oxide (FexOy) with different magnetic properties (Strong or weak magnetic) or different structures (hollow or solid) are used as the core. The experimental results show that the sample prepared by hollow structure and magnetic iron oxide as the core [(H)Fe3O4@SiO2@Ag] has good magnetic and SERS performance. The saturation magnetization is 34.01 emu/g. Detecting 10-6 M R6G, the SERS intensity at 1650 cm-1 is about 8×104 counts, and the enhancement factor is about 8.45×104. It is speculated that it is related to the suspension characteristics provided by the hollow structure and the appropriate size and spacing of Ag NPs. Analyze the recyclable SERS effect, It shows that the SERS signal is greatly reduced when using the second times. According to the microscopic image, it was found that Ag NPs were dropped. Indicating that the adhesion of Ag NPs had to be improved. 　　The second part is to prepare a SERS substrate with photocatalytic properties. TiO2 substrate is heat-treated in different atmospheres for defect modification, to improve its photocatalytic properties. The experimental results show that Ti3+ has an increasing tendency in the TiO2 substrate treated by reducing atmosphere. In the performance of light properties, the absorption range extends to the visible range, and the electron-hole composite light emission phenomenon is suppressed. After depositing Ag NPs on the above substrate, 10-6 M R6G was detected, showing an EF value of 2105.Analyzing the recyclable SERS effect, showing that recyclability is 9 times. However, the intensity of the ninth re-use was only 6% of the first time. It is speculated that the reason is that the cleaning process, the Ag NPs are detached or the displacement occurs, so that the place where the hot spot is provided is less, and the SERS effect is thus lowered. The adhesion of TiO2 and Ag needs to be improved.

APA, Harvard, Vancouver, ISO, and other styles

48

Lee, Cheng-Tao, and 李政道. "SERS in pre-blasted tungsten mold to press silvers as SERS-active substrates." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/64307816930700280213.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Hsu, Jui-Hung, and 徐瑞鴻. "Silver Nanostructure for Efficient SERS Substrate and Electrochemical Detection." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/29hu8t.

Full text

Abstract:

碩士
國立東華大學
光電工程學系
105
First, we use a simple dip-coating route to deposit silver nanowires (Ag NWs) on coffee filter (CF), which would function as a new type substrates of SERS and non-enzyme biosensor for detecting the H2O2 in this study. For SERS, the Ag NW/CF substrate exhibits low detection limit of 1x10-11 M for 4-Aminothiophenol (4-ATP). And for biosensor, the Ag NW/CF electrode exhibits detection limit of 0.1 mM and high sensitivity of 219 mAmM-1cm-2 for detection of H2O2 in concentration range 100 M ~ 25 mM. In order to find out the way to enhance the efficiency in the detections of H2O2 and SERS signal, we utilized the electrochemical growth technique to fabricate dendritic Ag NW on FTO substrate for achieving the low detection limit. Because the branched Ag NW/FTO has large active surface for electrocatalytic reaction, our results show a sensitivity of 1.44 mAcm-2mM-1 to H2O2 and the concentration range from 0.25M to 2.6 mM with a low detection limit of 0.25 mM. In addition, the branched Ag NW also exhibited an excellent and significant performance for molecular sensing by using SERS with ultra-low concentration detection limit of 1x10-16 M for 4-ATP. Finally, the branched Ag NW/FTO functions as photoelectrode for the detection of H2O2 under illumination based on the characteristics of SPR and electro-catalytic effects. In this study, we observed that the maximum photocurrent density of -0.2 mAcm-2 can be reached at potential -0.6 V v.s. Ag/Ag Cl and the reason is due to localized surface plasmon resonance leading to the contribution of the hot electrons in photocurrent.

APA, Harvard, Vancouver, ISO, and other styles

50

Wiercigroch, Ewelina. "Projektowanie nanoczujników SERS do detekcji markerów chorobowych." Praca doktorska, 2021. https://ruj.uj.edu.pl/xmlui/handle/item/289862.

Full text

Abstract:

Selektywna i szybka detekcja biomarkerów w złożonych próbkach biologicznych ma zasadnicze znaczenie w wykrywaniu chorób, wdrażaniu skutecznego leczenia oraz monitorowania skuteczności wprowadzanych terapii. Rozwój narzędzi diagnostycznych, które umożliwiają ich lokalizację, a także ilościową ocenę z wysoką czułością i niezawodnością, przyczyniają się do lepszej i szybszej diagnostyki, co ma ogromny wpływ na rokowania pacjenta i jego szanse przeżycia. Testy oparte na reakcjach immunologicznych są jednymi z najczęściej stosowanych metod w wielu obszarach diagnostyki klinicznej oraz badań naukowych, służąc detekcji składników takich jak specyficzne białka, hormony czy leki. Testy immunologiczne odgrywają kluczową rolę w wykrywaniu biomarkerów związanych z rozwojem wielu chorób i zaburzeń ze względu na ich wysoką czułość i selektywność. W ostatnim czasie szczególnie wiele uwagi poświęca się na testom immunologicznym opartym na detekcji i kwantyfikacji sygnału generowanego dzięki powierzchniowo wzmocnionej spektroskopii ramanowskiej (SERS). Silne wzmocnienie sygnału ramanowskiego wynikające z wykorzystania nanostruktur metalicznych umożliwia wykrywanie biomarkerów na bardzo niskim poziomie stężeń, a w połączeniu z reakcjami immunologicznymi możliwe jest skonstruowanie czujników do selektywnego wykrywania interesujących badacza składników próbki. Celem prowadzonych w ramach niniejszej pracy badań naukowych była konstrukcja sensorów do detekcji stanu zapalnego w tkankach oraz płynach biologicznych i realizowany był on poprzez dwie ścieżki badawcze. Pierwsza z nich poświęcona była opracowaniu czujników immunoSERS do selektywnego wykrywania markerów w tkance aorty z rozwiniętą miażdżycą. Aby to osiągnąć testowano różnego rodzaju nanocząstki złota oraz sposoby barwienia (metodą bezpośrednią i pośrednią). Ostatecznie opracowano protokół, który umożliwił poprawną detekcję komórek mięśniówki gładkiej, jednego z kluczowych elementów blaszki miażdżycowej. Bardzo ważnym aspektem było przeprowadzenie analizy ilościowej badanego markera, a także wykonanie jednoczesnej detekcji dwóch markerów w aorcie. W ramach drugiej ścieżki badawczej realizowano założenia konstrukcji czujnika do ilościowej oceny mediatorów zapalnych, których poziom zmienia się na długo przed wystąpieniem objawów choroby. Projektowany sensor składał się z dwóch głównych części. Pierwsza z nich obejmowała metaliczne podłoże zmodyfikowane w taki sposób, aby wychwycić badany analit z roztworu. Z kolei drugą z nich stanowiła immunosonda SERS, rozpoznająca analit unieruchomiony na podłożu i generujący sygnał SERS. W ten sposób stworzony sensor przypomina w budowie powszechnie stosowany test kanapkowy ELISA. Punktem wyjścia w tej ścieżce badawczej było testowanie różnych podłoży metalicznych, a następnie wybranie tych o najlepszych właściwościach SERS do budowy sensora. W kolejnym kroku opracowano i zoptymalizowano metodę modyfikacji zarówno stałego podłoża SERS jak i koloidalnych nanocząstek metalicznych, aby stworzyć kompletny czujnik kanapkowy. Co więcej zbudowano dwa systemy testów kanapkowych - konwencjonalny z użyciem jednego reportera ramanowskiego umiejscowionego w immunosondzie oraz z zastosowaniem dwóch reporterów - jednego związanego z immunosondą, a drugiego z podłożem stałym. Ostatnim etapem prowadzonych badań była ocena działania obu rodzajów sensorów oraz stworzenie krzywych kalibracyjnych dla interleukiny 6 w zakresie stężeń od 0 do 1000 pg/mL dla wybranych czujników. Na podstawie prowadzonych eksperymentów stwierdzono, że układ z dwoma reporterami ramanowskimi charakteryzuje się większą czułością w detekcji badanej interleukiny w stosunku do sensora opartego na jednym reporterze ramanowskim.
Selective and rapid detection of biomarkers in complex biological samples is essential in disease recognition, effective treatment and monitoring of the therapy efficacy. Development of diagnostic tools which enable detection and qunatification with high sensitivity and selectivity, could provide accurate and fast diagnosis. The latter plays a pivotal role on the patient’s prognosis and chance of survival. Immunoassay is one of the most common method for the analysis of biochemical targets such as specific proteins, nuclei acids, hormones or drugs. And it has been routinely employed in many areas of clinical diagnostics and life -science research. As a robust and sensitive technique, immunoassay plays a key role in the detection of disease and disorder-associated biomarkers. Recently, surface enhanced Raman scattering (SERS) is increasingly considered as an ultrasensitive and rapid assay readout in the immunoassay techniques. Because of strong enhancement of Raman signal due to plasmonic features of metallic substrates, this technique is extremely useful in detection of biomarkers even at ultra-low concentrations. Based on immunological reaction, it is possible to construct a SERS sensor for the selective detection of various targets of interests. The main scientific goal of the doctoral thesis was to design immunosensors for detecting specific inflammation markers in tissues and biological fluids. This aim was realized through two research paths. The first one was devoted to the development of immunoSERS sensors for the selective detection of markers in aortic tissue with developed atherosclerosis. To achieve that, various types of nanostructures and staining approaches (direct and indirect methods) were tested. Designed immunoSERS probes allowed for the localisation of smooth muscle cells, one of the key components of atherosclerotic plaque. A very important aspect was to perform the quantitative analysis of the tested marker as well as the simultaneous detection of two markers within the same tissue. Another essential direction of the doctoral thesis was to design a diagnostic test for the quantitative detection of inflammatory mediators in blood plasma as their level can increase before disease symptoms. The SERS-based immunoassay platform involved two parts. The first one included a capture surface modified with specific antibodies that bind antigen from a sample, while the second part is based on a SERS immunoprobe which recognizes the analyte immobilized on the substrate and provides SERS readout. This construction resembles the commonly used ELISA sandwich test. The starting point for this research path was to test various metallic substrates and then select those with the high SERS properties. In the next step, a method for modifying both the substrate and metallic nanoparticles was developed and optimized to construct a complete sandwich sensor. Moreover, two types of the sandwich strategy were evaluated – the conventional design with one Raman reporter conjugated with metal nanoparticles and with two Raman reporters conjugated with metal nanoparticles and metal solid film. The last step of the research was to evaluate analytical performance of the designed SERS sandwich sensors based on calibration curves for interleukin 6 in the concentration range from 0 to 1000 pg/mL. It was found that the assay with the dual -reporter and dual SERS enhancement systems exhibit a better sensitivity in detection of investigated interleukin compared to the sensor with one Raman reporter only.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'SERS SUBSTRAT'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles