Modified Electrode Based on Immobilizing Horseradish Peroxidase on nano-Gold with Choline Covalently Modified Glassy Carbon Electrode as a Base

Glassy carbon electrode was covalently modified with choline, which can improve the activity of the electrode markedly. The choline film on the modified electrode with plenty of positive charges could adsorb nano-Au colloids with negative charges, and the nano-Au colloids could immobilize horseradish peroxidase (HRP) to form a hydrogen peroxide (H2O2) sensor. The electrochemical characteristics of the biosensor were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). As the result showed, the biosensor was with a good catalytic activity. The surface coverage of HRP (Γ*) was 1.2 × 10−9 mol cm−2, and the KMapp of HRP at the biosensor was determined to be (1.55 ± 0.11) mM. The linear response of the modified electrode to H2O2 was in the range of 1.2 × 10−6−3.2 × 10−3 M with a detection limit of 4.0 × 10−7 M. The modified electrode could be easily prepared and it exhibited good selectivity and stability.