Plasmonic Substrates: Toward Surface-Enhanced Raman Spectroscopy In Vivo Biosensing

Park, Ji Eun

doi:https://doi.org/10.21985/n2-s74z-tm35

Work

Plasmonic Substrates: Toward Surface-Enhanced Raman Spectroscopy In Vivo Biosensing

Public

Download PDF

Download All Files (.zip)

Raman spectroscopy is an analytical technique that utilizes inelastic scattering of light to obtain structural information of analyte molecules. The weak intrinsic process of Raman scattering, however, can be greatly enhanced when molecules are placed on or near a surface of noble metal with nanostructures. Discovered over 40 years, surface-enhanced Raman spectroscopy (SERS) is a well-established tool that enhances the weak Raman effect up to about eight orders of magnitude and opened up a variety of applied studies such as art conservation, catalysis, electrochemistry, and biomedical sensing. SERS is an attractive technique particularly for biosensing because it is highly sensitive, chemically specific, and portable, enabling real-time in situ measurements in biofluids. Among many existing plasmonic substrates for biosensing, microneedle-based and nanopipette-based platforms have recently gained attention due to their ability to reach biofluids in vivo in a minimally invasive manner. In this thesis, we develop and implement different concepts for SERS sensors, with particular emphasis in in vivo biosensing. First, we introduce polymeric microneedle arrays integrated with SERS-active nanoparticles functionalized with a pH-responsive Raman reporter molecule. We then demonstrate their sensing ability by detecting pH levels in solutions, agar gel skin phantom, and human skin. Second, we develop hydrogel-based plasmonic microneedle arrays with anti-biofouling properties and attempt to detect glucose using a boronic acid-based glucose capture ligand. Alternatively, owing to the difficulty of implementing the capture ligand, we conduct an investigation on the glucose-binding ability of the ligand. Third, we then develop a strategy for coping with these issues associated by employing surface potential as a physical capture agent. We fabricate ligand-free, conductive plasmonic microneedle arrays that have the ability to modulate analyte adsorption on the sensor surface by controlling the surface electric potential. Combined with multivariate analysis, the sensor enables discrimination of spectral responses of various anaytes in a mixture. Finally, we present a method for fabricating inexpensive and reliable nanopipette-based electrochemical SERS sensors by electrodeposition. Overall, this dissertation highlights the importance of developing innovative plasmonic biosensing substrates and the applicability of the substrates developed herein for SERS in vivo biosensing at different scales. The main contribution of this work is to develop these novel plasmonic platforms for successful implementation of SERS in the growing biosensing field and open new opportunites for disease diagnosis and health monitoring.

Creator