Detection of prostate specific antigen with 3,4-diaminobenzoic acid (DBA)–H2O2–HRP voltammetric enzyme-linked immunoassay system

A new voltammetric enzyme-linked immunoassay system of 3,4-diaminobenzoic acid (DBA)–H2O2–horseradish peroxidase (HRP) for sensitive detection of prostate specific antigen (PSA) in human serum was present. In the proposed procedure, labelled HRP efficiently catalyzed the oxidation reaction of DBA by H2O2 and generated the electroactive product, 2,2′-biamino-4,4′-bicarboxyl azobiphenyl, which produced a sensitive second-order derivative linear sweep voltammetric peak at potential of −0.62 V (versus SCE) in Britton–Robinson (BR) buffer solution. The linear range for detection free HRP was from 4.0 × 10−12 to 4.0 × 10−9 g ml−1 and the detection limit was about 6.0 × 10−13 g ml−1. The proposed new system could be used for detection of PSA ranging from 0.20 to 16.0 ng ml−1 with a detection limit of 0.10 ng ml−1, which was five times lower than that of the traditional o-phenylendiamine spectrophotometric enzyme-linked immunosorbent assay (ELISA) method. The proposed electrochemical ELISA method is simple, inexpensive, reproducible and sensitive, which shows potential for detecting PSA in clinical diagnosis.