Abstract
The accurate and highly sensitive detection of the tumor marker CYFRA21-1 is crucial for screening and diagnosing potential lung cancer patients with non-small cell lung cancer (NSCLC). A sandwich-type photoelectrochemical (PEC) immunosensor based on a ZnO/poly(5-formylindole) (P5FIn)/anthocyanin heterostructure was developed to achieve sensitive background-free detection of CYFRA21-1. ZnO with good photovoltaic properties is combined with narrow bandgap P5FIn to form a p-n type heterojunction. This structure reduces the recombination efficiency of electron-hole pairs, thereby enhancing the photocurrent response of the composite. Anthocyanidins are environmentally friendly natural compounds with excellent antioxidant, redox properties, and remarkable electrochemical activity. After sensitization by anthocyanins, the absorption and utilization of visible light in the composites are enhanced, further improving the PEC luminescence efficiency of the materials. Additionally, boron nitride quantum dots (BN QDs) are combined with Ab2 via polydopamine (PDA) as a secondary antibody marker, enhancing its sensitivity. The sensor exhibited a linear detection range (LDR) of 0.001-100 ng mL− 1 with limit of detection (LOD) of 0.00033 ng mL− 1. Furthermore, this sensor demonstrates excellent selectivity, reproducibility, and stability, as well as successful results in detecting actual human serum samples. This approach provides a feasible method for tumor marker detection.