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摘要
In this work, a novel and ultrasensitive sandwich-type electrochemical immunosensor was developed for the quantitative detection of prostate specific antigen (PSA), a well-known prostatic tumor biomarker. A 3D-structured reduced graphene oxide-multiwalled carbon nanotube-palladium nanoparticle (NP) nanocomposite (rGO-MWCNT-Pd) was prepared in a simple and environmentally friendly way and utilized for the adsorption of secondary antibodies (Ab(2)). It is used as a novel enzyme-mimicking label to develop a sandwich-type electrochemical immunosensor for signal amplification, and shows better electrocatalytic activity for the reduction of hydrogen peroxide (H2O2) than rGO-CNT or rGO-Pd due to the synergetic effect of the rGO-MWCNT-Pd nanocomposite. The nanocomposite of Au NPs decorated on aminated graphene (Au-NH2-GS) is used as a platform for the immobilization of primary antibobies (Ab(1)) via an amide reaction between the -NH2 group of the Au-NH2-GS and the -COOH groups of Ab1. Due to the excellent electrocatalytic activity of rGO-MWCNT-Pd for the reduction of H2O2, electrochemical amperometric changes at different concentrations of PSA were studied after the immunoreaction. Under the optimum experimental conditions, the proposed electrochemical sandwich-type immunosensor exhibits a low detection limit (0.17 pg mL(-1)), and a wide linear range (from 0.5 pg mL(-1) to 15 ng mL(-1)) for the detection of PSA. It also shows high sensitivity, good selectivity and stability, and has great potential in clinical and diagnostic applications.
