Modified Biosensor for Cholinesterase Inhibitors with Guinea Green B as the Color Indicator.

Colorimetric biosensors of cholinesterase inhibitors are ideal for fast, reliable, and very simple detection of agents in air, in water, and on surfaces. This paper describes an innovation of the Czech Detehit biosensor, which is based on a biochemical enzymatic reaction visualized by using Ellman's reagent as a chromogenic indicator. The modification basically consists of a much more distinct color response of the biosensor, attained through optimization of the reaction system by using Guinea Green B as the indicator. The performance of the modified biosensor was verified on the chemical warfare agents (sarin, soman, cyclosarin, and VX) in water. The detection limits ascertained visually (with the naked eye) were about 0.001 µg/mL in water (exposure time 60 s, inhibition efficiency 25%).