▎ 摘　　要

NOVELTY - Photoelectrochemical biosensor comprises oxytetracycline aptamer-titanium dioxide-reduced graphene oxide (TiO2/RGO)-fluorine-doped tin oxide (FTO) electrode, where the oxytetracycline aptamer comprises a 77 base pair sequence (SEQ ID NO: 1) fully defined in the specification. USE - The photoelectrochemical biosensor is useful for determining oxytetracycline in water sample (claimed). ADVANTAGE - The photoelectrochemical biosensor determines oxytetracycline in water sample in a stable, reliable, and cost-effective manner with high selectivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) method for preparing photoelectrochemical biosensor involves preparing nano-TiO2 by hydrothermal method on FTO conductive glass to obtain TiO2-FTO conductive glass electrode, electrochemically reducing and depositing graphene oxide solution on TiO2-FTO conductive glass electrode to obtain TiO2-RGO-FTO electrode, and then modifying oxytetracycline aptamer on TiO2-RGO-FTO electrode; (2) use of photoelectrochemical biosensor for determining oxytetracycline in water sample; and (3) method for determining oxytetracycline in water sample involves adding oxytetracycline aptamer photoelectrochemical biosensor to phosphate-buffered saline (PBS) buffer solution diluted with water to be measured in the sample, reacting at 30-60 degrees C for 1 hour, washing the sample with ultrapurified water, and then using electrochemical workstation for signal detection using ampere current-time curve method with initial potential of -0.2 V for 30-100 seconds to detect the sensor before and after the oxytetracycline reaction photocurrent value.