Photoelectrochemical immunosensor for carcinoembryonic antigen detection-an attempt for early cancer screening

A photoelectrochemical (PEC) immunosensor based on MIL-101(Cr) and CdTe-QDs composites (M&C) was successfully synthesized to assay the carcinoembryonic antigen (CEA) in human serum and urine samples. This novel method contained three key aspects: 1), the polarity of the photocurrent based on MIL-101(Cr) itself could be altered by applying a different voltage to detect the cathode and anode photocurrent. 2), the introduction of cadmium telluride quantum dots (CdTe-QDs) greatly improved the efficiency of light utilization. 3), the photogenerated electron-hole-pairs were suppressed and their separation efficiency was improved by effective matching of energy level between MIL-101(Cr) and CdTe-QDs. Due to the inherent insulating properties of the biological matrix, the transfer of photogenerated electrons was hindered, leading to a decreased photocurrent signal. Under the optimal condition, the anodic and cathodic detection limit of the PEC immunosensor for CEA was 0.00018 ng mL^-1 and 0.00023 ng mL^-1, respectively. The linear range was 0.0001-10 ng mL^-1. The developed PEC immunosensor showed acceptable stability and sensitivity for the analysis of human serum and urine samples. For future perspective, using PEC and 3D-printing technology, a small PEC detector was designed with the potential to detect tumor markers.