Specific phages-based electrochemical impedimetric immunosensors for label-free and ultrasensitive detection of dual prostate-specific antigens

Abstract

It is significant and challenging to develop dual immunosensors for the detection of the ratio of free/total prostate-specific antigen (f-PSA/t-PSA ratio) in human serums and introduce low-cost and highly specific probes in the design of f-PSA/t-PSA immunosensors. In this contribution, we developed the dual label-free immunosensors to detect f-PSA/t-PSA ratio, by the integration of phage display andPhage display electrochemical impedance spectroscopy (EIS). The proposed strategy eliminated complicated purification of recognition elements. The fabrication steps and morphology characterization of the immunosensing interface were studied. Under the optimal conditions, the proposed immunosensors demonstrated wide linear ranges (0.02 pg mL−1 – 200 ng mL-1 for f-PSA; 0.02 pg mL−1 – 200 ng mL−1 for t-PSA), satisfactory specificity, excellent reusability, high reproducibility and good storage stability. Moreover, the immunosensors showed remarkably lower limits of detection (3 fg mL−1 f-PSA, S/N = 3; 4 fg mL−1 t-PSA, S/N = 3) than other reported methods. These merits could be attributed to good specificity, affinity and biocompatibility of the multicopy octapeptides on the phage scaffold, the fibrous nanostructure of phage, and the inherent advantages of EIS method. The proposed label-free impedimetric immunosensing platform would open an avenue for the bio-marker diagnosis.