Double-Layer Nanogold and Poly(amidoamine) Dendrimer-Functionalized PVC Membrane Electrode for Enhanced Electrochemical Immunoassay of Total Prostate Specific Antigen

A simple and portable electrochemical immunosensor for the detection of total Prostate specific antigen (t-PSA) in human serum was developed using a double-layer nanogold particles and dendrimer-functionalized polyvinyl chloride (PVC) membrane as immunosensing interface. To fabricate such a multifunctional PVC electrode, an o-phenylenediamine-doped PVC membrane was initially constructed, then nanogold particles and poly(amidoamine) G4-dendrimer with a sandwich-type format were assembled onto the PVC membrane surface, and then t-PSA antibodies (anti-PSA) were adsorbed on the nanogold surface. The detection principle of the immunosensor is based on the change in the electric potential before and after the antigen-antibody interaction. The experimental conditions and the factors influencing the performance of the immunosensor were investigated. Under optimal conditions, the proposed immunosensor exhibits good electrochemical behavior in the dynamic range of 0.5 - 18 ng/mL relative to t-PSA concentration with a relative low detection limit of 0.1 ng/mL (S/N=3). The precision, reproducibility, and stability of the immunosensor are acceptable. In addition, 43 serum specimens were assayed by the as-prepared immunosensor, and consistent results were obtained in comparison with those obtained by the standard enzyme-linked immunosorbent assay (ELISA). Compared with the conventional ELISAs, the developed immunoassay system was simple and rapid without labeling and separation steps. Importantly, the immobilization and detection methodologies could be extended for the immobilization and detection of other biomarkers.