Dual electrode configurations with a plant tissue as generator reactor

Abstract

Amperometric bioelectrodes prepared from tissues open up several biosensing possibilities. Dual-electrode configurations with a tissue reactor generating electroactive species that are hydrodynamically swept and detected amperometrically are described. A series-flow thin-layer detector and a rotating ring-disk electrode are characterized and offer significant advantages for biosensing applications and for the evaluation of biological materials. The selection of enzyme-rich tissue regions for biosensing applications is facilitated by constructing “maps” of the catalytic activity. Definite spatial variation of the enzymatic activity is observed. The kinetic behavior of the enzyme in the tissue is characterized by varying the convection rate and from Lineweaver-Burke plots. Because of the absence of diffusional barriers, dual-electrode devices respond very rapidly to changes in the substrate concentration. For flow-injection determination of dopamine by using the banana generator-carbon paste collector, the relative standard deviation is 1.5%, the detection limit is 1.9×10 −6 M and the injection rate is 45 samples per hour. Preliminary results are also given for the horseradish root/hydrogen peroxide and mushroom/cathechol systems.