Label-free amperometric immunosensor based on prussian blue as artificial peroxidase for the detection of methamphetamine

A label-free amperometric immunosensor for the detection of methamphetamine was developed. The prussian blue deposited/l-cystine-modified electrode was covered with nano-Au/(3-mercaptorpropyl) trime-thoxysilane film. Then, the nano-Au was used for the immunosensor platform to capture a large amount of anti-methamphetamine. PB exhibited excellent electrocatalytical properties toward the reduction of H₂O₂ at low overpotentia to amplify the amperometric signal, which enhanced the sensitivity of the immunosensor. The active sites of PB could be shielded and the access of H₂O₂ from solution to the electrode might be partially blocked after the completion of immunoassay, led to a linear decrease in the response current of the electrode over the range from 1.0 × 10⁻⁸ to 5.0 × 10⁻⁶ mol L⁻¹of MA. The obtained immunosensor displayed excellent catalytic reduction toward H₂O₂ due to high activity and selectivity of PB. The influence of relevant experimental variables, including the construction of immunosensor platform, the amount of MPS and the time of immunoaction, was examined and optimized.