Electrochemical polymerization of toluidine blue and its application for the amperometric determination of β-D-glucose

Poly(toluidine blue) modified electrodes were successfully fabricated by cyclically sweeping the graphite electrode in the potential range -0.3 to 1.3 V (Is SCE) in aqueous buffer solutions containing 5.0 x 10(-3) M toluidine blue. The effect of pH on the polymerization process of toluidine blue and the electrochemical characteristics of the resulting polymer-modified electrodes were studied in detail. The experimental results indicated that the polymerization of toluidine blue could be carried out in a wide pH region. Particularly, its polymerization process was somewhat similar to that of aniline in acidic media. These polymer-modified electrodes showed redox activity in phosphate media and they have been further successfully used as mediators for the catalytic oxidation of reduced nicotinamide adenine dinucleotide (NADH). Meanwhile, a glucose enzyme electrode, constructed by immobilizing glucose dehydrogenase during the polymerization of toluidine blue, was developed. A good linear amperometric response to beta-D-glucose in the range 5.0 x 10(-5)-3.0 x 10(-3) M was obtained. (C) 1998 Elsevier Science Ltd. All rights reserved.