Enhanced electrocatalytic activity of graphene-gold nanoparticles hybrids for peroxynitrite electrochemical detection on hemin-based electrode.

A simple, ultrasensitive peroxynitrite anion (ONOO-) electrochemical sensing platform was developed by immobilizing hemin on a density controllable electrochemically reduced graphene oxide-Au nanoparticles (ERGO-AuNPs) nanohybrids. The ERGO-AuNPs in situ nanohybrids were produced onto a glass carbon electrode (GCE) by one-step electrodeposition, the density of which could be easily controlled by electrodeposited time. The morphology of ERGO-AuNPs nanohybrids was characterized by a scanning electron microscope (SEM). The ERGO-AuNPs nanohybrids showed a high electrocatalytic activity for immobilized-hemin, because the nanostructures hybrids could effectively promote electron transfer rate between hemin and the electrode. Due to nanohybrids-enhanced catalytic effect for hemin, they were firstly selected for use as a highly sensitive electrochemical platform for ONOO- detection. The resulted sensor showed a high electrocatalytic activity toward ONOO- oxidation, being free from the electroactive interferents, including nitrite, nitrate, dopamine and uric acid at an applied potential of 0.7V. The sensor exhibited a high sensitivity of 123.1nAμM-1 and a lower detection limit of 0.1μM, and a wide linear range of 2.4×10-6 to 5.5×10-5M, which could be attributed to the synergy between ERGO and AuNPs in hybrids. The nanohybrids in situ preparation and ONOO- detection methods would be beneficial to developing other sensing interface and have promising applications in biological molecules analysis and clinical diagnostic.