A novel signal amplification system fabricated immunosensor based on Au nanoparticles and mesoporous trimetallic PdPtCu nanospheres for sensitive detection of prostate specific antigen

•The m-PdPtCu was first used as the label of secondary antibodies in immunosensor.•The m-PdPtCu showed an excellent performance in signal amplification.•The immunosensor enabled highly sensitive and selective detection of PSA.•The designed immunosensor is promising in early clinical diagnosis of biomarkers. In this work, the gold nanoparticles (Au NPs) substrate and the prepared mesoporous trimetallic PdPtCu nanospheres (m-PdPtCu) as the label of secondary antibodies (Ab2, Ab2 labeled probe) were used as the basis for fabricating a highly sensitive immunosensor to detect trace amount of prostate specific antigen (PSA) in human serum. The Au NPs can provide a suitable microenvironment for immobilizing primary antibodies (Ab1) and accelerate the electron transfer on the electrode interface due to the good biocompatibility and conductivity. The sensitivity of immunosensor was greatly amplified by the designed novel Ab2 labeled probe, which can be attributed to the m-PdPtCu with mesoporous structure not only can provide high specific surface area, but also offer abundant catalytically active sites and accessible pores for reactants. Under the optimal conditions, a linear relationship between current responses and the logarithm of the PSA concentrations were obtained in the wide range of 10 fg mL−1–100 ng mL−1 and the detection limit was 3.3 fg mL−1. Remarkably, the detection result of PSA in real human serum samples by the immunosensor is well in correlation with commercial ELISA, which confirms that the immunosensor is promising in early clinical detection of biomarkers.