Date of Award


Degree Type


Degree Name

Master of Science




Dr. Heinz-Bemhard Kraatz


This work attempts to detect hepatitis C viral (Hep CV) NS3-4A protease and prostate specific antigen (PSA) proteins using electrochemical methods. The sensing probes used in detecting these biological markers are their inhibitory peptides. The inhibitory peptide for the hepatitis C viral NS3-4A protease is Asp-Glu-Ile-Val-Pro-Nva with an IC50of 7.5 pM and the inhibitory peptide for prostate specific antigen is the peptide Ser-Lys-Ser- Lys-Ser-Lys-Ser-Cys-Val-Phe-Ala-His-Asn-Tyr-Asp-Tyr-Leu-Val-Cys with a K, of 0.8 pM.

The steps involved in the fabrication of the sensor surface include the formation of a self assembled monolayer (SAM) using a thioctic acid modified ferrocene compound. The use of a thioctic acid labelled compound facilitates the chemisorption of the ferrocene probe to the electrode surface. The SAM is then diluted using an ethanolic solution of hexanethiol. This will help backfill the films and remove physisorbed molecules from the electrode surface. The sensing probes are then covalently attached to the surface and are used for subsequent studies with either NS3-4A protease or PSA.

Our studies show that the Hep CV NS3-4A protease can be detected using the biosensor approach at very low concentrations and this sensor approach is also very specific in the presence of high concentrations of human serum albumin (HSA). The changes in sensor surface can be directly correlated to the concentration o f the protease.

Studies using this approach with PSA also show similar result.



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