Platinum nanoparticle-modified carbon fiber ultramicroelectrodes for mediator-free biosensing

A novel platinum nanoparticle-modified carbon fiber ultramicroelectrode (Pt/CFUME) is proposed for the construction of a mediator-free amperometric ultramicroelectrode biosensor. The platinum nanoparticles electrodeposited on the ultramicroelectrodes greatly increase the surface areas with enhanced electron transfer characteristics between the electroactive centers of enzymes and the ultramicroelectrodes. By using horseradish peroxidase (HRP) as an enzyme model, we construct a mediator-free amperometric ultramicroelectrode HRP sensor for detecting H2O2. The resultant biosensor well displays the direct electrochemical behavior of HRP on the Pt/CFUME and the electrocatalytic response to the reduction of H2O2 without the aid of electron mediators. The steady-state response current is linearly related to the H2O2 concentration in the range of 0.64 μM–3.6 mM with a detection limit of 0.35 μM (S/N = 3) and a correlation coefficient of 0.9953.