Electrochemical Immunosensor for Detection of Prostate Specific Antigen Based on CNSs/Thi@AuNPs Nanocomposites as Sensing Platform

A sensitive immunosensor for quantifying prostate specific antigen (PSA) had been described. In the design, gold nanoparticles decorated thionine-functionalized carbon nanospheres (CNSs/Thi@AuNPs) for immobilization of primary antibody (Ab 1 ) as an electrochemical sensing platform. Silicon dioxide nanospheres (SiO 2 NSs), with large surface area and good biocompatible, were loaded with horseradish peroxidase (HRP) and horseradish peroxidase labeled secondary antibodies (HRP-Ab 2 ). In the presence of PSA, a sandwich type immunocomplex from Ab 1 -Ag-Ab 2 had been formed. Differential pulse voltmmetry (DPV) was employed to obtain the response signal of immunosensor. Under the suitable experimental conditions, the changes of current intensity were linear with the logarithm of PSA concentration from 0.1 pg·mL -1 to 100 ng·mL -1 , and the detection limit was 0.025 pg·mL -1 (S/N=3). Moreover, the immunosensor possessed satisfactory specificity, repeatability and stability, suggesting that it had potential application value in the detection of tumor markers.