Hydrogen peroxide biosensor based on hemoglobin-modified gold nanoparticles-screen printed carbon electrode

A biosensor based on hemoglobin immobilized on screen-printed carbon electrode (SPCE) pre-electrodeposited with gold nanoparticles (AuNPs) was developed to measure hydrogen peroxide (H2O2) concentration. Cyclic voltammetry method was utilized for AuNPs electrodeposition process and characterized the Hb behaviour in the modified electrode. The highest electro active surface area (0.07 cm(2)) of working electrode in SPCE was obtained when the potential was swept (in electrodeposition experiment) from 0 to +1 V for 15 cycles in phosphate buffer solution (PBS) (pH 7) containing 0.1 nM AuNPs. Direct electrochemical of hemoglobin in the modified electrode showed quasi-reversible redox behaviour at -0.2 V and -0.3 V on forward and revers scan respectively, in PBS (pH 7) at scan rate 0.05 Vs(-1) vs. Ag/AgCl. The modified electrode was used to measure hydrogen peroxide concentration with a linear response over 3 mu M to 240 mu M and a detection limit of 0.6 mu M at -0.35 V. The apparent Michaelis-Menten constant value of Hb in the modified SPCE to measure H2O2 was calculated to be 235 mu M with sensitivity of 0.918 AM(-1) cm(-2). The surface morphology of the SPCE and its modification were investigated using Atomic Force Microscope (AFM). As a result, the new modified biosensor exhibited a high sensitivity, good reproducibility and stability.