Date of Award


Document Type


Degree Name

Master of Science


Department of Systems Engineering and Management

First Advisor

Dirk P. Yamamoto, PhD.


Previous work to develop biosensors that can be used to detect organophosphorus compounds (OPCs) has successfully demonstrated the potential application of enzymes encapsulated in peptide-nanotubes (PNTs) enhanced with horseradish peroxidase (HRP) to detect the presence of OPCs in the aqueous and gas phases. In this research, a standardized test method that was applied to evaluate a biosensor fabricated with a single-use electrode, was refined to accommodate a reusable screen printed electrode. Also in this study, butyrylcholinesterase (BChE) enzyme was used in lieu of the acetylcholinesterase (AChE) enzyme applied in earlier studies in an effort to enhance biosensor performance. Biosensor operation is based on the principle that butyrylthiocholine (BSCh), in the presence of the enzyme BChE, will produce a measurable electrochemical signal during chemical reaction; a signal that is inhibited in the presence of an OPC. For this research, cyclic voltammograms (CVs) were used to measure the inhibition in current due to the presence of a model OPC, malathion. The response of a BChE-based biosensor was shown to be inhibited by gas phase malathion concentrations less than 25 ppbv, with the extent of inhibition linearly proportional to the malathion concentration above 6 ppbv. Additionally, this study demonstrated that a BChE-based biosensor stored at room temperature can be used as long as 42 days after fabrication.

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