Superoxide dismutase-like cerium dioxide hollow sphere-based highly specific photoelectrochemical biosensing for ascorbic acid

Conventional N-type semiconductor-based photoelectrochemical (PEC) sensors are difficult to achieve high selectivity for ascorbic acid (AA) detection in real samples because co-existing reducing agents act as hole sacrificial agents like AA to promote the increase of photocurrent. Cerium dioxide (CeO2) is a superoxide dismutase-like nanozyme with the reversible Ce3+/Ce4+ redox pair as well as one of alternative N-type semiconductors. To address the problem of PEC detection selectivity of AA, bifunctional CeO2 is a good choice. Herein, a novel and rational PEC biosensor for AA is constructed based on CeO2 hollow spheres as both AA superoxide dismutase-like nanozyme and the photoelectric beacon, which enable the PEC approach with high selectivity. In this protocol, AA can selectively induce a decrease in the CeO2-based photoanode current, which is significantly different from the conventional N-type semiconductor-based PEC sensor, this unique working mechanism is also proposed. The results show that the CeO2-based photocurrent response decreases linearly with AA concentrations in the ranges of 1 μM–600 μM and 600 μM–3000 μM, with a limit of detection of 0.33 μM. Moreover, the fabricated PEC biosensor has advantages of cost-effectiveness, replicability, and stability. Additionally, the sensor is competent for AA determination in practical settings and has achieved satisfactory results.