A label-free electrochemical immunosensor based on facet-controlled Au nanorods/reduced graphene oxide composites for prostate specific antigen detection

Abstract

Prostate specific antigen (PSA) is one of the most common tumour markers and indicators for prostate cancer. However, the trace concentration of PSA in serum expresses higher performance requirements for reliable detection. In this study, a simple but competitive label-free electrochemical immunosensor was constructed to detect PSA using subtly facet-controlled Au nanorods-functionalized reduced graphene oxide (Au NRs/rGO). A strong initial electrochemical current signal was achieved by modifying Au NRs with more pronounced surface concavity and indentation on fluorine-doped tin oxide (FTO) electrodes because of their enhanced conductivity. The specific structure and properties of facet-controlled Au NRs not only accelerate electron transfer kinetics but also offer an effective matrix for efficient conjugation of biomolecules due to surface modified cetyltrimethylammonium bromide (CTAB). The optimal immunosensor exhibits a wide linear range between 0.1 and 150 ng mL−1, and the calculated detection limit is down to 0.016 ng mL−1, together with good resolution, high selectivity and reliable long-term stability. The presented immunosensor also exhibits good performance in human serum analysis, which exhibits good potential for application in the clinical screening of cancer biomarkers and can be extended as a sensitive platform for a variety of target analytes.