Simple fabrication of a sensitive hydrogen peroxide biosensor using enzymes immobilized in processable polyaniline nanofibers/chitosan film

A simple method for polyaniline nanofibers modified glassy carbon electrode was developed. Polyaniline nanofibers (4-toluenesulfonic acid as dopant) were synthesized by interface polymerization. The polyaniline nanofibers had better processability than conventional polyaniline and were easily dispersed in chitosan solution. The mixed dispersion of polyaniline nanofibers and horseradish peroxidase was cast onto the glassy carbon electrode by a drop-coating method. The use of polyaniline nanofibers led to efficient enzyme loading and rapid electron transfer rate between the active centers of enzymes and electrodes. Horseradish peroxidase entrapped in the polyaniline nanofibers/chitosan film could keep its native bioactivity and effectively catalyze the reduction of hydrogen peroxide. The proposed biosensor exhibited good analytical performance due to the benefits of nanostructured polyaniline. This biosensor had a wide linear range of 1 × 10− 5 to 1.5 × 10− 3 M and correlation coefficient of 0.998 (n = 17), with the detection limit of 5 × 10− 7 M based on signal-to-noise ratio of 3.