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In this thesis, we report the use of DNA diluents to reduce surface fouling in peptide-containing, thiol-gold self-assembled monolayers. Two antimicrobial peptides previously developed as therapeutics for Methicillin-resistant Staphylococcus aureus (MRSA) USA300 LAC, P1 and P2, were selected as the peptide probes. Both systems were first tested and verified to form stable monolayers on gold electrode surfaces. Their responses in the presence of two complex biological samples, 50 % simulated nasal mucus and undiluted human serum were recorded. A large reduction in the redox signal from the methylene blue label on the peptide probes was observed, indicating severe surface fouling. To minimize surface fouling, two thiolated DNA diluents, tetra-thymine (T4) and tetra-adenine (A4), were separately incorporated into the P1 and P2 systems, and their responses upon exposure to the two matrices were analyzed. All four systems with a DNA diluent, P1/T4, P1/A4, P2/T4, and P2/A4, showed significantly lower signal reduction, verifying the antifouling capabilities of the two DNA diluents. Although this study’s immediate focus was not on the detection of USA300 LAC, the results are invaluable. It has laid the foundation for future advances in the design and fabrication of electrochemical peptide-based MRSA sensors.
Advisor: Rebecca Y. Lai