Poly(aniline)–poly(acrylate) composite films as modified electrodes for the oxidation of NADH

Abstract

Poly(aniline), electrochemically deposited on an electrode surface in the presence of poly(acrylic acid), forms a Ðlm which remains protonated, and conducting, at pH 7. The resulting modiÐed electrode is an electrocatalytic surface for NADH oxidation at ]0.05 V vs. SCE in 0.1 M citrateÈphosphate bu †er at pH 7. The amperometric responses of these composite poly(aniline) Ðlms for NADH oxidation were studied in detail and Ðtted to a kinetic model in which the NADH di †uses into the polymer Ðlm and then binds to catalytic sites within the Ðlm where it undergoes reduction to NAD`. The rate determining process depends on the concentration of NADH present and the polymer Ðlm thickness. A comparison of the results presented here for the poly(aniline)Èpoly(acrylate) Ðlms with earlier work on poly(aniline)Èpoly(vinylsulfonate) Ðlms shows that the currents obtained for NADH at these poly(aniline)Èpoly(acrylate) Ðlms are approximately one third of those obtained for the poly(aniline)Èpoly(vinylsulfonate) Ðlms under similar conditions, that the currents saturate at lower NADH concentration and that the response is less stable towards repeated measurements. The poly(aniline)Èpoly(acrylate) Ðlms are, however, less readily inhibited by NAD`and possess the potential advantage that the carboxylate groups can be used as sites for chemical attachment of enzymes or NADH derivatives by using simple coupling reactions.

Electroactivity of Polyaniline Multilayer Films in Neutral Solution and Their Electrocatalyzed Oxidation of β‐Nicotinamide Adenine Dinucleotide

“…The above results are similar to those found for PANI copolymers. [11,12] Figure 4 shows the cyclic voltammograms of 6 bilayers of PANI/SPANI recorded in 0.1 M PBS buffer (pH 7.1) at different scan rates. The inset shows the plot of the anodic peak current versus the square root of the scan rate.…”

“…For PANI copolymers this process was reported to be surface controlled. [12] The difference may arise from the different structures of PANI/SPANI multilayer films and PANI copolymers. The former is more ordered and compact than the latter.…”

Preparation of an Electrode Modified with an Electropolymerized Film as a Mediator of NADH Oxidation and Its Application in an Ethanol/O2 Biofuel Cell

“…When the oxidation of NADH was conducted using an unmodified GCE, the electrochemical oxidation peak was observed at around + 0.56 V. The decrease in overpotential indicated that the imine group of pAPRu catalyzed the electrochemical oxidation of NADH as a mediator. The potential of pAPRu is comparable to that of other mediators of NADH oxidation, such as poly(aniline)-poly(anion) composites [21][22][23], However, poly(aniline) could not catalyze the electrochemical oxidation of NADH when poly-(aniline) lost its conductivity. To maintain the conductivity, the polymeric counter anion used as a dopant was entrapped within the poly(aniline) film [21,22].…”

“…The potential of pAPRu is comparable to that of other mediators of NADH oxidation, such as poly(aniline)-poly(anion) composites [21][22][23], However, poly(aniline) could not catalyze the electrochemical oxidation of NADH when poly-(aniline) lost its conductivity. To maintain the conductivity, the polymeric counter anion used as a dopant was entrapped within the poly(aniline) film [21,22]. However, the pAPRu/GCE could catalyze the electrochemical oxidation of NADH without doping.…”

“…For mediators of NADH oxidation prepared via electropolymerization, electropolymerized films of a metal complex containing 1,10-phenanthroline-5,6-dione [15], polymerized dyes [17,18], and poly(aniline)-poly(anion) composites [21][22][23] were reported. We are especially interested in poly(aniline)-poly(anion) composites.…”