Paper-based photoelectrochemical immunoassay for ultrasensitive screening of carcinoembryonic antigen on hollow CdS/CdMoO4-functionalized photoanode

Lab-based testing systems utilizing photoelectrochemical (PEC) biosensing methodologies for the ultrasensitive carcinoembryonic antigen (CEA) have been developed, although the majority have shown complicated operating procedures and dependence on precise apparatus. Herein, a portable photoelectrochemical split diagnostic platform based on a hollow CdS/CdMoO4 (h-CdS@CdMoO4) shell-shell structured photoanode system was developed for ultrasensitive detection of CEA. Using a small LED flashlight as the excitation light source and a digital multimeter (DMM) as the signal readout device, real-time CEA on a paper-based printed screen electrode developed in-house was quickly detected. The composite h-CdS@CdMoO4 featured a special hollow shell-shell heterojunction structure that optimizes photon usage in the bulk phase on the one hand, and facilitates directed separation of the electrons and holes therein on the other. A split-sandwich immunoassay and detection antibodies for modified glucose oxidase were introduced into the paper-based photoanode test system, and the signals were displayed with a DMM to realize a point-of-care test for CEA. Under optimized conditions, the constructed portable PEC sensing system was sensitive to the target CEA from 0.02 to 50.0 ng mL-1 with a detection limit of 11.3 pg mL-1. Interferent experiments and stability test evaluations demonstrate the specificity and robustness of the constructed paper-based portable PEC sensor. The portable, paper-based PEC immunoassay system developed offers a fresh way of exploring affordable, approachable sensors to satisfy both the relevant community medical testing demands and hospital objectives for quick testing.