Construction of an enzymatic sensor for visual measurements with redox dyes immobilized on the inner surface of a glass tube

Abstract

An enzymatic glucose sensor for visual measurements was constructed using glucose oxidase (GOD), catalase (CAT) and redox dyes. Enzymes and viologen dyes were entrapped in silica gel on the inner surface of a glass tube by means of the sol-gel method. Viologen dye has blue color in its reduced form and no color in its oxidized form. First, sodium dithionite was introduced into the glass tube and viologen dye was reduced. A sample was then introduced. The color of the glass tube faded due to soluble oxygen in the sample solution, but it took more time to fade the color in the presence of glucose, because glucose oxidase and catalase, which were entrapped in the gel, consumed soluble oxygen. Based on the color fading time or the color fading length, the glucose in sample solution was quantified. The quantification range was between 0.1 and 10 mM and the RSD was within 4%. The fading color simulation of this sensor was programmed and performed. The simulation results were compared with the experimental data.