Photoelectrochemical detection of human epidermal growth factor receptor 2 (HER2) based on Co 3 O 4 -ascorbic acid oxidase as multiple signal amplifier

A sensitive photoelectrochemical (PEC) sensor based on hexagonal carbon nitride tubes (HCNT) as photoactive material was prepared for the detection of human epidermal growth factor receptor 2 (HER2). Magnetic Fe 3 O 4 nanospheres (MNs) modified with anti-HER2 antibodies were employed for highly efficient capture of HER2 from serum sample, and Co 3 O 4 nanoparticles (Co 3 O 4 NPs) modified with ascorbic acid oxidase (AAO) as well as HER2 aptamer were used for signal amplification. When the aptamer-Co 3 O 4 -AAO probe was captured onto the electrode surface through the specific binding of the aptamer with HER2, the photocurrent intensity decreased. This was because Co 3 O 4 NPs competed with HCNT for consumption of the excitation energy. As a consequence AAO catalyzed the oxidation of the electron donor (AA), and the aptamer-Co 3 O 4 -AAO probe increased the steric hindrance at the electrode surface, leading to significant photocurrent intensity decrease, thus realizing multiple signal amplification. Based on this signal amplification strategy, at 0 V (vs Ag/AgCl), the PEC sensor shows a wide linear response ranging from 1 pg mL −1 to 1 ng mL −1 with a low detection limit of 0.026 pg mL −1 for HER2. Importantly, the prepared PEC sensor was applied for detection of HER2 in human serum samples with recoveries between 98.8 and 101%. Graphical abstract Sensitive photoelectrochemical sensor based on Co 3 O 4 nanoparticles modified with ascorbic acid oxidase for signal amplification is reported.