Fundamental Studies on the Development of a Biosensor for Nicotinamide Determination

Abstract

Prototype of nicotinamide-biosensor system was constructed, for the first time, with partially purified nicotinamidase (EC 3.5.1.19) from "Toramakitake" mushroom, ion sensitive field effect transistors (ISFET), a differential amplifier, a high sensitive potentiometer and a personal computer. The enzyme ISFET and reference ISFET were prepared by immobilizing the enzyme and bovine serum albumin on each ISFET. The ultra small change of pH on the enzyme ISFET, which was caused by nicotinamidase reaction dependent on the nicotinamide concentration, was measured potentiometrically. The differential voltage (mV) between both ISFET at stationary phase was plotted against the logarithm of nicotinamide concentration (molarity) to obtain calibration curve. As the result, linear relationship was observed among 60-160mM of nicotinamide with a relation coefficient of 0.989. Possibility for practical use of this new type of nicotinamide sensor was suggested.