Ultrasensitive amperometric immunosensor for PSA detection based on Cu2O@CeO2-Au nanocomposites as integrated triple signal amplification strategy

In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of prostate specific antigen (PSA). To this end, the amino functionalized cuprous oxide @ ceric dioxide (Cu2O@CeO2-NH2) core-shell nanocomposites were prepared to bond gold nanoparticles (Au NPs) by constructing stable Au-N bond between Au NPs and -NH2. Because the synergetic effect presents in Cu2O@CeO2 core-shell loaded with Au NPs (Cu2O@CeO2-Au), it shows better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than single Cu2O, Au NPs and Cu2O@CeO2. Featured by large specific surface area, good biocompatibility and good electrochemical properties which can greatly improve the electronic transmission rate, Cu2O@CeO2-Au was used as transducing materials to achieve efficiently capture antibodies and triple signal amplification of the proposed immunosensor. Under the optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.1 pg/mL to 100 ng/mL with a low detection limit of 0.03 pg/mL (S/N=3). Furthermore, the proposed label-free immunosensor has been used to determine PSA in human serum with satisfactory results. Meanwhile, it displayed good reproducibility, acceptable selectivity, and long-term stability, which had promising application in bioassay analysis.