A "signal-on" photoelectrochemical sensor for human epidermal growth factor receptor 2 detection based on Y6/CdS organic–inorganic heterojunction

A "signal-on" photoelectrochemical (PEC) immunosensor was successfully constructed for determination of human epidermal growth factor receptor 2 (HER2) based on organic–inorganic heterojunction Y6/CdS as photoactive material. Compared with single organic semiconductor, Y6, Y6/CdS exhibited higher photoelectric conversion efficiency due to the formation of heterojunction. In the presence of HER2, sandwich immune structure was formed between HER2 aptamer and anti-HER2 antibody (Ab) by specific recognition. The polydopamine (PDA) nanoparticles were used for signal amplification to enhance photocurrent intensity as PDA can act as electron donor to eliminate holes and promote electron–hole pairs separation. The developed PEC sensor displayed a wide detection range of 5–1000 pg mL⁻¹ and a low detection limit of 2.2 pg mL⁻¹ for HER2 (S/N = 3). The sensor was successfully used for the detection of HER2 in serum with recoveries between 94.8 and 104% and relative standard deviations (RSDs) in the range of 1.2–4.3%. Furthermore, the designed immunosensor possessed good stability, selectivity, and reproducibility, which can find potential clinical applications for disease diagnosis. Graphical abstract A "signal-on" photoelectrochemical sensor was reported for human epidermal growth factor receptor 2 detection based on Y6/CdS organic–inorganic heterojunction