Label-free photoelectrochemical aptasensor for tetracycline detection based on cerium doped CdS sensitized BiYWO₆

A novel photoelectrochemical (PEC) aptasensor based on cerium (Ce) doped CdS modified graphene (G)/BiYWO₆ was designed, which exhibits enhanced PEC intensity compared with pure BiYWO₆, G/BiYWO₃ and BiYWO₆/Ce:CdS. In this scenario, ascorbic acid (AA) was exploited as an efficient and non-poisonous electron donor for scavenging photogenerated holes. The doping of Ce in CdS promoted its visible light absorption range and facilitated the charge transfer rate as well as hindered the h⁺/e^- recombination. Moreover, the combination of G further promoted the electron carrier separation and transfer process due to its excellent electron collection and shuttling characteristic. Thus, the G/BiYWO₆/Ce:CdS heterostructure was successfully served as a matrix for the PEC detection of tetracycline (Tc) at 0 V (vs Hg/Hg₂Cl₂). Under optimal conditions, the PEC aptasensor could offer a sensitive and specific detection limit (3 S/N) of Tc down to 0.01 ng/mL, as well as acceptable reproducibility, selectivity and storage stability, which opened up a promising pathway for the development of PEC biosensors.