A novel H ₂O ₂ amperometric biosensor based on gold nanoparticles/self-doped polyaniline nanofibers

A new kind of gold nanoparticles/self-doped polyaniline nanofibers (Au/SPAN) with grooves has been prepared for the immobilization of horseradish peroxidase (HRP) on the surface of glassy carbon electrode (GCE). The ratio of gold in the composite nanofibers was up to 64%, which could promote the conductivity and biocompatibility of SPAN and increase the immobilized amount of HRP molecules greatly. The electrode exhibits enhanced electrocatalytic activity in the reduction of H ₂O ₂ in the presence of the mediator hydroquinone (HQ). The effects of concentration of HQ, solution pH and the working potential on the current response of the modified electrode toward H ₂O ₂ were optimized to obtain the maximal sensitivity. The proposed biosensor exhibited a good linear response in the range from 10 to 2000μM with a detection limit of 1.6μ M (S/N=3) under the optimum conditions. The response showed Michaelis-Menten behavior at larger H ₂O ₂ concentrations, and the apparent Michaelis-Menten constant K _m was estimated to be 2.21mM. The detection of H ₂O ₂ concentration in real sample showed acceptable accuracy with the traditional potassium permanganate titration.