Indian Journal of Science and Technology

Abstract

A novel sensor approach based on measurement of changes in capacitance of an electrochemical cell produced during enzyme catalyzed formation of products is described. The electrochemical property such as capacitance of an electrolyte between electrochemical cell depends on its ionic compositions, in turn depends on the resulting ionic constituents caused by catalytic action of the enzyme. Generation of micromolar (μM) concentration of ionic species causes large changes in capacitance that is measurable in picofarad (pF) range in capacitive electrodes. Broad clinical analytical application of this technique is demonstrated in this report by application to diagnostically valued enzymes measurements like pyrophosphatases and phosphatases. Specific measurements of enzyme activities were achieved over the concentration range of 0.125 – 5.0 mM of respective substrates. The performance of the electrochemical sensor based enzyme biochemical assays were compared directly with identical assays employing spectrophotometric detection and found to match well.
Keywords: Capacitance Changes, Electrochemical Cell, Enzyme Kinetics, Shigella Apyrase