Colorimetric immunosensor for determination of prostate specific antigen using surface plasmon resonance band of colloidal triangular shape gold nanoparticles.

were synthesized using Tween-20 as a nonionic surfactant and then, conjugated with PSA capture antibody (Ab1-AuNPs). When exposed to Ab1-AuNPs, PSA antigens were found to be successfully captured by nanosystem (PSA)-Ab1-AuNPs. Next, (PSA)-Ab1-AuNPs were incubated with second PSA antibody (2)-decorated magnetite (Fe3O4-Ab2) and separated by an external magnetic force to leave Ab1-AuNPs in the supernatant solution to be directly analyzed using UV–Vis spectroscopy. It was found that the absorption intensity was directly proportional to the PSA concentration. As a result, the linear range for PSA detection was found to be 0.01–20 ng mL−1 with a detection limit of 0.009 ng mL−1. Because of significant stability of the prepared Ab1-AuNPs and excellent selectivity to the PSA antigen, this simple and sensitive sensing system is proposed to be potentially effective in the fast and real-time analysis of clinical samples from prostate cancer patients. We believe that the simple platform of this immunosensor to be useful in the development of future point-of-care sensing tools, working on the quantification of biomarkers in a drop of blood.