Date of Award

2016

Document Type

Thesis

Degree Name

Bachelor of Science

Department

Chemistry

First Advisor

Dr. Michael Leopold

Abstract

The research conducted in the Leopold Bioanalytical and Nanomaterials Analytical Chemistry Lab prior to the summer of 2013 focused on the synthesis of a functional biosensor equipped with a nanoparticle network embedded in a xerogel film for the detection of glucose. Xerogel-based films featuring embedded glucose oxidase enzyme and doped with alkanethiolate-protected gold NPs, known as monolayer protected clusters (MPCs), exhibit significantly enhanced performance compared to analogous systems without NPs including higher sensitivity, faster response time, and extended linear/dynamic ranges.

The following presented research is a systematic study of the structure-function relationships critical to understanding the sensing mechanism of the 1st generation glucose biosensor with an embedded nanoparticle (NP) network. The proposed mechanism involves diffusion of the glucose to glucose oxidase enzyme within the xerogel, enzymatic reaction production of H2O2 with subsequent diffusion to the embedded network of MPCs where it is oxidized, an event immediately reported via fast electron transfer (ET) through the MPC system to the working electrode. To confirm our theory, various aspects of the film construct and strategy are systematically probed using amperometry, voltammetry, and solid-state electronic conductivity measurements, including the effects of MPC peripheral chain length, MPC functionalization via place-exchange reaction, MPC core size, and the MPC density or concentration within the xerogel composite films.

The results of these experiments support the proposed mechanism and identify interparticle spacing and the electronic communication through the MPC network as the most significant factors in the sensing scheme with the diffusional aspects of the mechanism that may be affected by film/MPC hydrophobicity and functionality (i.e., glucose and H2O2 diffusion) shown to be less substantial contributors to the overall enhanced performance. The importance of understanding the mechanism behind the enhanced performance of MPC doped xerogel biosensors is for its application for future biosensor design toward clinically relevant targets.

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