Simultaneous photoelectrochemical and visualized immunoassay of β-human chorionic gonadotrophin

Herein, on the basis of the alkaline phosphate (ALP) induced reaction, a simultaneous photoelectrochemical (PEC) and visualized immunoassay has been established for the detection of β-human chorionic gonadotrophin (β-HCG). Specifically, in the proposed system, ALP stimulated the oxidative hydrolyzing transformation of 5-bromo-4-chloro-3-indoyl phosphate (BCIP) to an indigo precipitation, generating an insulating layer that impeded the interfacial mass and electron transfer and thus the photocurrent production. Meanwhile, a visualized detection could be performed according to the change of color intensity. Upon proper experimental conditions, the protocol possessed a detection range of 0.5-1000IU/L with a detection limit of (0.20±0.011)IU/L toward β-HCG. With high sensitivity and specificity, this work presents the first general protocol for simultaneous PEC and visualized detection, which could be easily extended to addressing numerous other targets.