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

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No. of bitstreams: 1 alinelucianofilgueiras.pdf: 4846834 bytes, checksum: f046903a257bca51b49b36d371931270 (MD5) Previous issue date: 2017-03-24 / Nesta tese investigou-se as interações químicas dos antimicrobianos tinidazol, metronidazol, aztreonam, rifampicina e tetraciclina (TC) adsorvidos sobre superfícies metálicas de nanopartículas de ouro (AuNP) ou prata (AgNP) através das técnicas espectroscópicas de espalhamento Raman intensificado por superfície (SERS), de espalhamento Raman ressonante intensificado por superfície (SERRS) e de absorção no ultravioleta, visível e infravermelho próximo (UV-VIS-NIR). Também foram investigadas, a citotoxidade das AgNP, quitosana (QUIT), TC e das combinações AgNP com quitosana (AgNP+QUIT), e AgNP com QUIT e TC (AgNP+QUIT+TC) frente a células de fibroblastos bovinos. Foram obtidas as imagens de microscopia eletrônica de transmissão (TEM) das bactérias K.pneumoniae e S. aureus na ausência e presença das AgNP. Diferentes rotas sintéticas de AuNP e AgNP foram propostas, com o objetivo de se aprimorar as possíveis aplicações dessas sínteses. As AgNP devem ser pequenas para aplicações em experimentos biológicos e devem estar em ressonância com as radiações excitantes de comprimento de onda em 532, 633 ou 1064 nm quando forem utilizadas nos experimentos SERS. Os espectros SERS dos adsorbatos estudados foram obtidos na ausência e na presença dos modificadores de superfície 2-mercaptoetanol, polivinil álcool (PVA) ou íons cloreto. A presença destes modificadores superficiais permitiu monitorar os mecanismos de adsorção, que levaram a padrões espectrais SERS distintos. A análise dos espectros SERS da rifampicina foi baseada nas modificações observadas na estrutura eletrônica do grupo cromóforo, enquanto que para o tinidazol, metronidazol e aztreonam as diferenças nos padrões espectrais foram devidas a proximidade do sítio de adsorção do analito em relação à superfície metálica. A atribuição vibracional dos espectros Raman e SERS foi baseada em cálculos teóricos obtidos da teoria do funcional de densidade (DFT) das moléculas isoladas ou interagindo com átomos de metal. Este trabalho foi realizado em parceria com o Prof. Dr. Diego Paschoal da Universidade Federal do Rio de Janeiro e com o Prof. Dr. Hélio Ferreira dos Santos da Universidade Federal de Juiz de Fora. As imagens TEM das bactérias K. pneumoniae e S.aureus obtidas na ausência e presença das AgNP+QUIT foram realizadas em colaboração com o Dr. Celso Sant’Ana e o aluno Mateus Eugênio do Instituto Nacional de Metrologia, Qualidade e Tecnologia. Os ensaios de citotoxicidade das diferentes combinações de AgNP frente as células de fibroblastos bovinos foram realizados através do ensaio colorimétrico com brometo de 3, (-4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium (MTT). Este trabalho foi realizado em colaboração com a Profa. Dra. Michele Munk da Universidade Federal de Juiz de Fora. / In this thesis were investigated the chemical interaction of the antimicrobians tinidazole, metronidazole, aztreonam, rifampicin and tetracycline adsorbed on metallic surfaces of gold (AuNP) or silver nanoparticles (AgNP) by using the spectroscopic techniques surface enhanced Raman scattering (SERS), surface enhanced resonance Raman scattering (SERRS) and absorption in ultraviolet, visible and near infrared regions (UV-VIS-NIR). The cytotoxic effects of silver nanoparticles, chitosan (QUIT), tetracycline (TC) and its combinations AgNP with chitosan (AgNP+QUIT), and AgNP with QUIT and TC (AgNP+QUIT+TC) against bovine fibroblast cells were also investigated. The images using transmission electron microscopy (TEM) were obtained from the bacteria K.pneumoniae and S. aureus in the absence and presence of AgNP +QUIT. Different AuNP and AgNP were synthesized, with the aim of improving the possible applications of these syntheses. These have to be small in the biological experiments and should be in resonance with laser lines at 532, 633 or 1064 nm when used in the SERS experiments. The SERS spectra of the studied adsorbates were obtained in the absence and presence of the surfaces modifiers 2-mercaptoethanol, chloride ions or polyvinyl alcohol (PVA). The presence of these surfaces modifiers allowed monitoring adsorption mechanisms, which led to distinct SERS spectral patterns. The analyses of the SERS spectra of rifampicin were based on the observed changes in the electronic structure of the chromophore group, while for the tinidazole, metronidazole and aztreonam the differences in the spectral patterns were due to the proximity of anchor site of the analyte in relation to the metallic surface. The vibrational assignments of the Raman and SERS spectra were based on theoretical calculations obtained from density functional theory (DFT) of the isolated molecules or in interaction with metallic atoms. The DFT studies were made in collaboration with the Prof.Dr.Diego Paschoal from Universidade Federal do Rio de Janeiro and Prof.Dr Hélio Ferreira dos Santos from Universidade Federal de Juiz de Fora. The TEM images of K. pneumoniae and S.aureus bacteria obtained in the absence and in the presence of AgNP+QUIT were made in collaboration with the researcher Celso Sant’Ana and its student Mateus Eugênio from Instituto Nacional de Metrologia, Qualidade e Tecnologia. The cytotoxicity assays of the different combination of AgNP and chitosan and tetracycline against bovine fibroblast cells were made though colorimetric assay using MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The biological assay were made in collaboration with the Prof.Dr. Michele Munk and its students Leonara Fayer and Rafaella Zanetti from Universidade Federal de Juiz de Fora.

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

The increasing market demand for fresh produce promotes a keen interest in developing a rapid, sensitive and reliable method for monitoring plant health and determining the shelf-life of postharvest produce. The objective of this study is to explore the capability of Surface-enhanced Raman spectroscopy (SERS) in these applications. SERS integrates Raman spectroscopy which measures molecular vibrations and nanotechnology which enhances the weak Raman signals. Herein, we developed two SERS methods based on a surface detection approach using nanoparticles solution and a headspace detection approach using gold nanoparticles (AuNPs) fibers, to detect biochemical changes during postharvest storage of arugula leaves. Compared with surface detection, the headspace detection revealed significant spectral changes during the storage, particularly in the shifts around 500, 950 and 1030 cm-1. These changes analyzed using principal component analysis (PCA) to establish a prediction model for shelf-life determination. Through analyzing reference standard compounds, we identified the dimethyl disulfide (DMDS), 1-propanethiol and methanethiol (MT) were most likely to account for the signature spectra of headspace arugula at the late storage period due to the activities of spoilage bacteria. The headspace detection method was also applied to monitor the stress responses of living basil to abiotic stresses (pesticide/salinity). However, the volatile analysis of the basil plants response to abiotic stresses (pesticide/salinity) showed indistinctive results. In conclusion, the headspace detection based on SERS provides a new strategy for quality monitoring of fresh produce in the food industry.

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

<p>This thesis highlights the use and significance of surface enhanced Raman spectroscopy (SERS) for forensic applications. Two unique SERS substrates are developed for successful (1) forensic toxicological drug detection in human patient plasma and (2) trace explosive detection.  </p>

No description available.

Metallic nanostructures supporting surface plasmon modes can concentrate optical fields, and enhance luminescence processes from the metal surface at plasmonic hotspots. Such nanoplasmonic metal luminescence contributes to the spectral background in surface-enhanced Raman spectroscopy (SERS) measurements and is helpful in bioimaging, nano-thermometry, and chemical reaction monitoring applications. Despite increasing interest in nanoplasmonic metal luminescence, little attention has been paid to investigating its dependence on voltage modulation. Also, the hyphenated electrochemical surface-enhanced Raman spectroscopy (EC-SERS) technique typically ignores voltage-dependent spectral background information associated with nanoplasmonic metal luminescence due to limited mechanistic understanding and poor measurement reproducibility. In this thesis, we combine the experimental observations and theoretical study on dynamic Faradaic & non-Faradaic modulated nanoplasmonic metallic luminescence and molecular vibrational Raman from hotspots at the electrode-electrolyte interfaces using multiple novel nano-optoelectrodes. Our work represents a critical step toward the general application of nanoplasmonic metal luminescence signals in optical voltage biosensing, hybrid optical-electrical signal transduction, and interfacial electrochemical monitoring. / Master of Science / Understanding the non-Faradaic and Faradaic process pathway is crucial for unraveling reaction mechanisms, developing efficient catalysts, designing bionsensing methodology, energy conversion and cellular stimulator (1-7). Advances in spectroscopic techniques( 8, 9) and computational models (3, 10) have facilitated the investigation of the non-Faradic and Faradaic processes. Unlike bulk reactions, interfacial electrochemical reactions occur in nanometer-thin layers (3, 11), necessitating highly sensitive detection methods. A significant challenge is background interference from bulk electrolytes and electrodes, often obscuring weak signals from the interfacial region – traditional spectroelectrochemistry struggles to match the high temporal resolution requirement due to noise (12, 13). Surface plasmons have become a promising solution for enhancing the sensitivity of spectroelectrochemical techniques (14, 15). Surface plasmons are collective oscillations of electrons at the metal-dielectric interface, which can focus and intensify optical fields at the nanoscale (16), boosting diverse nonlinear emission signals, including fluorescence, Raman scattering, and harmonic generation (17-23). By utilizing surface plasmons, spectroelectrochemistry techniques have shown promise in detecting interfacial activities with high sensitivity. In this thesis, we introduce a pioneering dual-channel in situ EC-SERS methodology, which harnesses the synergy between plasmon-enhanced vibrational Raman scattering (PE-VRS) and plasmon-enhanced electronic Raman scattering (PE-ERS) interfacial signals to monitor and analyze the Faradaic and non-Faradaic process at the electrode-electrolyte interfaces.

Many environmental compartments are acknowledged transmission routes for infectious diseases, antibiotic resistance, and anthropogenic pollution. The need for environmental sensing has consistently been stressed as a means to minimize public health threats caused by such contaminants. Many analytical detection techniques have been developed and applied for environmental sensing. However, these techniques are often reliant upon centralized facilities and require intensive resources. For these reasons their use can be challenging under resource-constrained conditions characterized by poor water, sanitation, and hygiene (WASH) services. In this dissertation, we developed biotechnology- and/or nanotechnology-advanced analytical tools for environmental sensing that have potential for future application in regions with poor WASH services. First, loop-mediated isothermal amplification (LAMP) and nanopore sequencing were applied to develop assays for the detection of SARS-CoV-2, the causative agent of COVID-19, in wastewater samples. Second, surface-enhanced Raman spectroscopy (SERS) was applied for environmental detection of a range of analytes. Gold nanoparticle (AuNP)-based SERS substrates were fabricated by droplet evaporation-induced aggregation on a hydrophobic substrate. These SERS substrates were then applied for the detection of antibiotic resistance genes (ARGs) and other environmental contaminants (e.g., dye or hydrophobic organic contaminants). In a separate study, Au nanostructured SERS substrates were fabricated and applied for pH sensing in a range of environmental media. Finally, the environmental impact of an AuNP-based colorimetric detection assay was assessed via life cycle assessment. / Doctor of Philosophy / Environmental sensing is an important means to intervene against public health threats of infectious diseases and environmental contaminants. However, currently available analytical tools for environmental samples often require intensive resources that are not available in low- and middle-income countries. In this dissertation, we developed biotechnology and/or nanotechnology advanced analytical tools for environmental sensing that have potential future application applied under resource-constrained conditions. First, we applied loop-mediated isothermal amplification (LAMP) and nanopore sequencing to develop detection assays for SARS-CoV-2, the causative agent of COVID-19, in wastewater samples. Second, we applied surface-enhanced Raman spectroscopy (SERS) to develop assays for environmental analytes. We fabricated SERS substrates by evaporation-induced aggregation of gold nanoparticles (AuNPs) on a hydrophobic substrate and applied these for the detection of antibiotic resistance genes (ARGs) and other environmental contaminants. In addition, Au nanostructured SERS substrates were fabricated and applied for pH sensing in a range of environmental media. Finally, we used life cycle assessment to quantitatively evaluate the environmental impacts of an AuNP-based sensing applications.

Non-invasive and continuous spatiotemporal pathogen monitoring at biological interfaces (e.g., human tissue) holds promise for transformative applications in personalized healthcare (e.g., wound infection monitoring) and environmental surveillance (e.g., airborne virus surveillance). Despite notable progress, current receptor-based biosensors encounter inherent limitations, including inadequate long-term performance, restricted spatial resolutions and length scales, and challenges in obtaining multianalyte information. Surface-enhanced Raman spectroscopy (SERS) has emerged as a robust analytical method, merging the molecular specificity of Raman spectroscopy's vibrational fingerprinting with the enhanced detection sensitivity from strong light-matter interaction in plasmonic nanostructures. As a receptor-free and noninvasive detection tool capable of capturing multianalyte chemical information, SERS holds the potential to actualize bio-interfaced spatiotemporal pathogen monitoring. Nonetheless, several challenges must be addressed before practical adoption, including the development of plasmonic bio-interfaces, sensitive capture of multianalyte information from pathogens, regeneration of nanogap hotspots for long-term sensing, and extraction of meaningful information from spatiotemporal SERS datasets. This dissertation tackles these fundamental challenges. Plasmonic bio-interfaces were created using innovative nanoimprint lithography-based scalable nanofabrication methods for reliable bio-interfaced spatiotemporal measurements. These plasmonic bio-interfaces feature sensitive, dense, and uniformly distributed plasmonic transducers (e.g., plasmonic nano dome arrays, optically-coupled plasmonic nanodome and nanohole arrays, self-assembled nanoparticle micro patches) on ultra-flexible and porous platforms (e.g., biomimetic polymeric meshes, textiles). Using these plasmonic bio-interfaces, advancements were made in SERS signal transduction, machine-learning-enabled data analysis, and sensor regeneration. Large-area multianalyte spatiotemporal monitoring of bacterial biofilm components and pH was demonstrated in in-vitro biofilm models, crucial for wound biofilm diagnostics. Additionally, novel approaches for sensitive virus detection were introduced, including monitoring spectral changes during viral infection in living biofilms and direct detection of decomposed viral components. Spatiotemporal SERS datasets were analyzed using unsupervised machine-learning methods to extract biologically relevant spatiotemporal information and supervised machine-learning tools to classify and predict biological outcomes. Finally, a sensor regeneration method based on plasmon-induced nanocavitation was developed to enable long-term continuous detection in protein-rich backgrounds. Through continuous implementation of spatiotemporal SERS signal transduction, machine-learning-enabled data analysis, and sensor regeneration in a closed loop, our solution has the potential to enable spatiotemporal pathogen monitoring at the bio-interface. / Doctor of Philosophy / Continuous monitoring of pathogens within our bodies and surrounding environments is indispensable for various applications in personalized healthcare (e.g., monitoring wound infections) and environmental surveillance (e.g., airborne virus tracking). To accomplish this, we require sensors capable of seamlessly interfacing with biological systems, such as human tissue, and consistently providing pathogen-related information (e.g., spatial location and pathogen type) over prolonged periods. Our research relies on Surface-enhanced Raman spectroscopy (SERS) to address this challenge. SERS enables noninvasive sensing by providing unique fingerprints of molecules near the sensor's surface. SERS holds the potential to enable bio-interfaced spatiotemporal pathogen monitoring, but several challenges must be tackled before practical adoption. In this dissertation, we address various fundamental challenges in SERS, including constructing SERS devices that can seamlessly interface with biological systems while maintaining performance, sensitively capturing pathogen-related information, extracting meaningful insights from SERS datasets, and continuously regenerating the sensor surface to ensure long-term performance. We developed SERS devices capable of seamlessly interfacing with biological systems using innovative scalable nanofabrication methods. These devices contain sensitive, dense, and uniformly distributed SERS sensors on flexible and porous platforms, such as polymeric scaffolds and textiles. Leveraging these SERS devices, we made advancements in pathogen sensing, data analysis, and sensor regeneration. We demonstrated large-area spatiotemporal monitoring of biofilm components and pH in lab-grown biofilm models, critical for wound biofilm diagnostics. Additionally, we introduced novel approaches for sensitive virus detection, including monitoring changes in SERS signals during viral infection in living biofilms and directly detecting decomposed viral components. The SERS datasets were analyzed using machine learning models to extract biologically relevant spatial and temporal information, such as the spatial location of pathogen components and the temporal stage of pathogen growth, and to predict biological outcomes. Finally, we developed a sensor regeneration method to enable long-term continuous detection in complex backgrounds, such as blood. By continuously performing spatiotemporal pathogen sensing, data analysis, and sensor regeneration in a closed loop, our solution has the potential to realize bio-interfaced spatiotemporal pathogen monitoring.