Sensitive Colorimetric Detection of Prostate Specific Antigen Using a Peroxidase-Mimicking Anti-PSA Antibody Coated Au Nanoparticle

The use of colorimetric bioassays for protein detection is one of the most promising diagnostic approaches, but their relatively poor detection limits have been a critical issue. In this study, we developed an efficient colorimetric bioassay based on antibody-coated peroxidase-mimicking Au nanoparticles (Au NPs) for the detection of prostate-specific antigen (PSA), which is one of the most widely used protein biomarkers for the diagnosis of prostate and breast cancers. Anti-PSA antibody adsorption on the Au NP surface result in 65% of the peroxidasemimicking properties of Au NPs was suppressed to maximize sensitivity of the assay. Anti-PSA antibody adsorption on the Au NP was optimized at 150 µg/mL anti-PSA4 antibody for 1 h incubation, and their surface was blocked with 2% BSA. The experimental conditions of the immunoassay detection were also investigated. A highest assay value was obtained at 10 µg/mL anti-PSA1 capture antibody using 3% BSA for surface blocking and at 2.5 pM anti- PSA4-Ab coated Au NPs for 1 h incubation with PSA antigen. As a result, PSA was detected at a wide range of 0.25 to 2,500 ng/mL with a detection limit of 0.23 ng/mL. The anti-PSA-Ab coated Au NP- based assay was simple, easy to operate, and sensitive. The proposed peroxidase-mimicking anti-PSA Ab-coated Au NP-based assay could be further developed to detect other protein biomarkers.