Detection of the human prostate-specific antigen using an aptasensor with gold nanoparticles encapsulated by graphitized mesoporous carbon

We report on a sensitive electrochemical aptasensor for the detection of human prostate specific antigen (PSA). It is based on the signal amplification of the biotin-avidin system using a sensing platform that is making use of a graphite electrode modified with gold nanoparticles that were covered with graphitized mesoporous carbon nanoparticles (AuNPs@GMCs). The AuNPs@GMCs hybrid was prepared by linking 1,6-hexanedithiol-functionalized GMCs and gold nanoparticles via Au-S groups. Then, streptavidin was immobilized on the electrode modified with the AuNPs@GMCs so to enlarge the amount of biotin-aptamer which led to enhanced detection sensitivity. If an PSA aptamer captures the target PSA on the electrode, the differential pulse voltammetric (DPV) signal of the hexacyanoferrate redox system decreases. Factors affecting the performance of the aptasensor were studied in detail. Under optimal conditions, the DPV signal changes could be used to quantitatively detect PSA in the concentration range from 0.25 to 200 ng mL−1, with a lowest limit of detection as small as 0.25 ng mL−1. The aptasensor is highly specific and displays acceptable precision, good stability and repeatability.