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Date of Award

Spring 2013

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science



First Advisor

Dr. Michael Leopold


First-generation amperometric glucose biosensors incorporating alkanethiolate-protected gold nanoparticles, commonly known as monolayer protected clusters (MPCs), within a xerogel matrix are investigated as model systems for the advancement of nanomaterial-assisted electrochemical sensing strategies. The xerogel biosensors are comprised of platinum electrodes modified with composite films of (3-mercaptopropyl)trimethoxy silane xerogel embedded with glucose oxidase enzyme, doped with MPCs, and an outer polyurethane layer. Electrochemical measurements and scanning/transmission electron microscopy, including cross-sectional TEM imaging, show sensor construction, humidity effects on xerogel structure, and successful incorporation of MPCs into the xerogels. Analytical performance of the biosensor scheme with and without doping of the xerogel layer with Au225(C6)75 MPCs is determined from direct glucose injection during amperometry. MPC inclusion within the xerogel yields significant enhancement of several sensor attributes compared to analogous films without nanoparticles: doubling of the linear range, drastic improvement of sensitivity by an order of magnitude, and four-fold faster response times. Long term stability and response to common interferents of the MPC-doped sensors are competitive with current literature on glucose biosensing. MPC chain length and MPC:silane ratio studies suggest the MPC-mediated sensing enhancements are critically related to structure-function relationships, particularly those affecting inter-particle electronic communication. The MPC network appears to behave as a three-dimensional extension of the working electrode into the xerogel film, reducing the system’s dependence on diffusion and maximizing efficiency of the sensing mechanism. The integration of MPCs as a functional component of amperometric biosensor schemes has implications for future development of biosensors and materials targeting clinically relevant species.