Cyclic voltammograms of HRP-AuNCs/MWCNTs/CFUME in 0.01 M pH 7.0 deoxygenated PBS at scan rates of 10, 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 mV/s
Description
We further investigated the effect of the scanning rates on the response of the HRP-AuNCs/MWCNTs/CFUME. Our results show that with the increase of the scan rates from 10 to 500 mV/s, the redox peak current increases linearly. Both the anodic and cathodic peak current of HRP is directly proportional to the scan rates (inset plot in Fig. 3), which suggests a typical surface-controlled electrochemical process. The average surface coverage of HRP was calculated to be 5.15×10-9 mol/cm2, according to the peak area of HRP in the cyclic voltammogram. That was about 600 times the theoretical monolayer coverage (8.5 × 10−12 mol/cm2) of HRP [19], indicating that multi-layers of HRP immobilized in the nanocomposite film participated in the electron transfer process. The anodic and cathodic peak potentials did not change with the increasing scan rate potentially due to the fast electron transfer process between HRP and the electrode surface, which also demonstrated that the modified film might provide HRP with a favorable microenvironment for facilitating electron transfer.