Bi3+ engineered black anatase titania coupled with graphene for effective tobramycin photoelectrochemical detection

Abstract Photoelectrochemical (PEC) sensing is an efficient method for trace tobramycin (TOB) detection, which poses a serious threat to public health. Therefore, this work developed a photoelectric nanohybrid, Bi3+ doped black anatase titania that was decorated with reduced graphene oxide (Bi3+/B-TiO2/rGO), which exhibited excellent PEC activity. Compared with pristine TiO2, B-TiO2, and B-TiO2/rGO, the PEC response of as-prepared Bi3+/B-TiO2/rGO was respectively 40.0-fold, 4.0-fold and 2.4-fold higher under visible light illumination. The photocurrent of B-TiO2 was enhanced compared with TiO2 due to the existence of oxygen vacancies (OVs), while the increased photocurrent of Bi3+/B-TiO2/rGO was ascribed to the presence of more OVs and an improved charge transfer rate. The proposed PEC aptasensor for the sensitive detection of TOB was constructed by combining Bi3+/B-TiO2/rGO with a specific aptamer. Under the optimal experimental conditions, the Bi3+/B-TiO2/rGO-based aptasensor exhibited a low detection limit of 0.33 pg/mL (S/N = 3) with a wide linear response range from 0.001 ng/mL to 50 ng/mL. The prepared Bi3+/B-TiO2/rGO may find potential applications as a photoactive material in PEC aptasensors.