Fluorophore-Induced Plasmonic Current

Abstract

Fluorescence-based detection is a technique that is heavily entrenched in analytical chemistry, biochemistry, and biological sciences. The use of a compounds ability to turn energy from light into a discreet photon at a different wavelength has been proven to be a useful tool, whether in the tracking of intracellular proteins via green fluorescent proteins, or by turn-on fluorescent probes that undergo physical changes in the presence of a contaminant like lead to alert to their presence. In nearly all examples of fluorescence, fluorophores are excited and detected in the far-field. While the use of fluorescence-based detection continues to grow, it is hampered by quantum yields, detectability, and photostability of the fluorophores used. Our group has worked on solving this dilemma with a technique known as metal-enhanced fluorescence (MEF), where the coupling between an excited-state fluorophore and a plasmonically active nanoparticle in the near-field can produce an enhanced emission that can be detected in the far-field. MEF has its issues, such as the need for 120V power sources, as well as traditional fluorescence detection structures, such as a photodetector, to achieve these enhancements. The research outlined in this thesis is the next evolution of this MEF concept, one where the coupling between the fluorophores and the plasmonic nanoparticles leads to a faster and more direct detection of these excited state compounds, namely fluorophore-induced plasmonic current (FIPC). FIPC is the direct detection of these excited state fluorophores as an induced current across a nanoparticle film. Herein we will show our recent advances in FIPC, namely; the use of new and novel metal nanoparticle substrates, a deeper dive into the fundamental mechanisms of FIPC detection and modulation, the use of FIPC as a means of assay development for both environmental and biological analytes, as well as the detection of other excited state reactions analogous to fluorescence. We conclude by discussing the future use of FIPC in new methods for onsite assay design in the titular objective “Fluorophore-Induced Plasmonic Current.”