Advances in Normal and Surface-Enhanced Raman Spectroscopy for Single-Molecule Electrochemistry and Non-Invasive Molecular Sensing

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Raman spectroscopy is an established and versatile molecular sensing technique, but it is limited by its modest chemical sensitivity. Surface-enhanced Raman spectroscopy (SERS) can amplify otherwise weak normal Raman signals up to nine to ten orders of magnitude, giving rise to its application in many molecular sensing problems, including those in catalysis, biosensing, and art conservation. Additionally, the excellent molecular sensitivity of SERS can be applied to studying chemical reactions at the single molecule limit. The first half of this thesis will highlight progress in monitoring single electron transfer reactions with single-molecule SERS (SMSERS) and its implications for nanoscale electrochemistry. We will then present the optimization of a procedure to covalently functionalize SERS-active substrates with a redox active molecule, which can achieve the ultimate goal of simultaneously monitoring both redox states of an electrochemical reaction with SMSERS. The second half of this thesis will explore the use of both NRS and SERS as non-invasive and label-free sensing techniques for point-of-care applications. We first investigate the limits of detection of both NRS and EC-SERS for use in intravenous (IV) therapy drug sensing and successfully demonstrate the ability to use both a tabletop and handheld Raman setup to perform IV drug sensing experiments. We then present a non-invasive means of detecting atherosclerotic plaques using spatially-offset Raman spectroscopy. Overall, the work presented in this thesis highlights the versatility of information obtained from Raman spectroscopy and SERS, as well as its applicability to a broad spectrum of molecular sensing problems. The work presented herein paves future pathways for the further implementation of SERS in the fields of nanoscale electrochemistry and point-of-care sensing.

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  • 02/26/2018
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