A SnO₂/Bi₂S₃-based photoelectrochemical aptasensor for sensitive detection of tobramycin in milk

Abuse of tobramycin (TOB) causes a series of diseases. Therefore, the development of rapid and sensitive method for analyzing TOB in food products is necessary. In this work, aptamer modified SnO₂/Bi₂S₃-based photoelectrochemical (PEC) sensor was developed for the determination of TOB in milk. Under optimal condition, a wide linear response for TOB from 5 to 50 nmol/L with a limit of detection of 4.28 nmol/L is reached. The possible detection mechanism is that TOB molecules are specifically captured by aptamer, increasing electron transfer resistance and declining the photocurrent. Thanks to the favorably matched energy level of SnO₂, and Bi₂S₃, the PEC aptasensor exhibits high sensitivity, and with the aid of oxalate, the sensitivity of the sensor is further improved. Importantly, the stability of the PEC aptasensor is also satisfactory due to the calcination of SnO₂/Bi₂S₃ at 450 °C.