A sandwich-type ECL immunosensor based on signal amplification using a ZnO nanorods-L-cysteine-luminol nanocomposite for ultrasensitive detection of prostate specific antigen

An ultrasensitive sandwich-type electrochemiluminescence (ECL) immunosensor was developed for detection of prostate specific antigen (PSA) using an amplification strategy based on ZnO nanorods- l -cysteine-luminol nanocomposites and the biotin-streptavidin system. The biotin-streptavidin system served as a capture probe to increase the number of antibodies. ZnO nanorods not only acted as a nanocarrier that increased the number of luminol molecules and secondary antibodies, but also enhanced the ECL signal of luminol-H 2 O 2 system by promoting H 2 O 2 decomposition, which can further increase ECL intensity. Under optimized conditions, the proposed immunosensor demonstrated excellent analytical performance with a wide linear detection range of 0.03 pg mL −1 to 30 ng mL −1 and a detection limit of 0.01 pg mL −1 (the detection limit in real samples was 0.021 pg mL −1 ). This method exhibited excellent stability, reproducibility, and selectivity. In addition, the results of PSA determinations in human serum samples obtained using the proposed immunosensor were consistent with data collected using the commercial chemiluminescence immunoassay analyzer.