Electrochemical assay of proteolytically active prostate specific antigen based on anodic stripping voltammetry of silver enhanced gold nanoparticle labels

This work demonstrated the determination of proteolytically active prostate specific antigen (paPSA), a potential biomarker for prostate cancer diagnosis, in human serum using a sensitive and low-cost electrochemical sensor. A specifically designed peptide probe was immobilized on the surface of a 96-well plate. The probe could be recognized by paPSA causing cleavage of the peptide, resulting in a decrease in the thiols group remaining on the probe. Gold nanoparticles (AuNPs) were attached to the peptide thiol groups by self-assembly. Hence the amount of AuNPs relates to the length of peptide probe. After cleavage and binding of AuNPs, an amplification step was performed using a silver enhancer solution. The quantity of deposited silver was then measured by differential pulse anodic stripping voltammetry (DPASV) using a disposable screen-printed carbon electrode (SPCE). The signal for paPSA detection was the linear range from 0.1 to 100 ng mL^− 1, with a detection limit of 27 pg mL^− 1. We also showed that the assay was reliable and has potential for clinical applications.