Ultrasensitive photoelectrochemical immunosensor for procalcitonin detection with porous nanoarray BiVO4/CuxS platform as advanced signal amplification under anodic bias

Abstract A new, porous nanoarray BiVO4/CuxS (PN-BiVO4/CuxS) platform as an advanced signal amplification strategy under anodic bias on the process of electrochemical catalysis assisted self-enhancing based photoelectrochemical (ECASE-based PEC) without electron donors was established for ultrasensitive procalcitonin (PCT) detection. The system operated upon that the PN-BiVO4/CuxS electrode could enhance separation of e-/h+ pairs under illumination of visible-light because the energy levels between BiVO4 and CuxS matched well. Afterwards, the photoexcited electrons could shift to working electrode as output signal, while the photoexcited holes could oxidize water under anodic bias to produce hydrogen peroxide (H2O2) that was subsequently reduced by CuxS, which resulted in significantly enhanced photocurrent intensity by electrochemical process. To further enhance the sensitivity of PEC immunosensor, amino-modified polystyrene (PS) nanoparticles act as labels for immobilizing secondary antibodies (Ab2) to form PS@Ab2 conjugates for construction of sandwich-type immunosensor on the basis of ECASE-based PEC strategy. The designed PEC immunosensor exhibited a linear concentration range from 50 fg mL-1 to 100 ng mL-1, with a low detection limit of 17.3 fg/mL (S/N = 3) for PCT, and achieved good selectivity, acceptable stability, and high sensitivity. This work first conducted the ECASE-based PEC system, and we believed it will provide a new perspective for developing innovative signal amplification toward detection of other biomarker in the future.