Digital multimeter-based point-of-care immunoassay of prostate- specific antigen coupling with a flexible photosensitive pressure sensor

Abstract This work designed a portable point-of-care (POC) immunosensing system for sensitive detection of prostate-specific antigen (PSA) in biological fluids by coupling a flexible photosensitive pressure sensor with digital multimeter (DMM) readout. Initially, photoactive methylammonium lead iodide (CH3NH3PbI3) and poly(vinylidene fluoride) (PVDF) were used for the fabrication of the flexible photosensitive pressure sensor. Thereafter, a sandwich-type immunoreaction was carried out on the capture antibody-coated microplate using platinum nanoparticle (PtNP)-labeled secondary antibody. Accompanying formation of sandwiched immunocomplexes, the carried PtNP could catalyze the decomposition of hydrogen peroxide (H2O2) to produce oxygen gas (O2). The as-produced gas squeezed flexible photosensitive pressure sensor to cause the piezoelectric potential on the sensing film, thus accelerating the separation of transfer of the generated electron-hole pairs under 365 nm light irradiation. The change in the resistance could be determinated on a portable digital multimeter. Under optimum conditions, DMM-based immunoassay exhibited good analytical properties toward target PSA within the dynamic linear range of 0.02 – 50 ng mL-1 at a detection limit of 12.6 pg mL-1. Meanwhile, DMM-based immunosensing system gave good specificity, high reproducibility and long-time storage stability. Importantly, human serum samples containing target PSA were assayed with DMM-based immunoassay, and well-matched results were acquired between our system and commercialized human PSA ELISA method.