Date on Master's Thesis/Doctoral Dissertation

5-2024

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Physics and Astronomy

Degree Program

Physics, PhD

Committee Chair

Mendes, Sergio

Committee Co-Chair (if applicable)

Sumanasekera, Gamini

Committee Member

Sumanasekera, Gamini

Committee Member

Yu, Ming

Committee Member

O'Toole, Martin

Author's Keywords

Plasmon wave; DNA sensor; electrohemical impedance spectroscopy; optical impedance spectroscopy; electron transfer

Abstract

This study offers a thorough comparative analysis of optical and electrical signaling strategies for assessing the electrochemical properties of different redox-labeled DNA-based biosensing platforms. In addition, it illustrates the development of an optical interrogation technique with electrochemical modulation of surface plasmon waves (ECM-SPW) as a route for analyzing and implementing DNA-based hybridization sensors. For those quantitative analyses, we chose a model sensing platform composed of a methylene blue (MB)-modified single-stranded DNA (ssDNA) signaling probe and an unlabeled capture ssDNA probe that complements the signaling probe. Two types of signaling probes were employed in this work: one with MB attached to the 3' end, which positions the redox marker closer to the electrode surface upon hybridization with the capture probe, and the other with MB attached to the 5' end, which places the redox marker farther from the electrode surface. We carried out complementary investigations by employing electrochemically driven protocols such as cyclic voltammetry and impedance spectroscopy while collecting both optical and electrical signals to quantitatively analyze and compare the strength of the electrochemically active redox process for each redox label position and the rate of electron transfer between the redox marker and the electrode surface. Due to its immunity to non-faradaic background signals, our results indicate that an optical impedance spectroscopy technique utilizing ECM-SPW can be a superior route to the traditional purely electrical impedance spectroscopy (EIS) technique for developing redox-labeled DNA sensors.

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