Electrochemical immunosensor using artificial enzyme-induced metallization for the ultra-sensitive detection of alpha fetoprotein

During the long incubation process of an electrochemical immunosensor, the sensitivity and detection limit of the sensor are seriously affected because the signal label easily falls off. In this work, we proposed an innovative artificial enzyme-induced metallization process. Firstly, an artificial enzyme is used to catalyze the solution to produce a reducing substance. Subsequently, metal ions in the solution are reduced to the surface of the electrode. Finally, the metal is dissolved by electrochemically, and the peak current is proportional to the alphafetoprotein (AFP) concentration. As a Lewis acid, CeO2 can hydrolyze phosphate bonds, and the hydrolysate ascorbic acid (AA) can reduce silver nanoparticles. In addition, the Au@CeO2 yolk shell nanostructure (Au@CeO2 YSNs) can greatly improve the catalytic activity of CeO2 and the conductivity of the signal tag. More importantly, since the signal substance is deposited on the electrode surface as soon as it is generated, the loss of electrical signals is reduced. Results show that the immunosensor has good analytical performance, a detection range of 0.1 pg/mL to 200 ng/mL, a detection limit of 0.035 pg/mL, and it performs well in serum samples. Therefore, this strategy provides a novel method for the early screening of AFP.