A highly sensitive photoelectrochemical aptsensor based on photocathode CuInS2 for the detection of tobramycin

• Modification of AuNPs improved the stability of p-type CuInS 2 electrodes and provided binding sites for aptamer. • Specific binding effect of aptamer and target allowed photocurrent signal to change with high selectivity. • The cathode PEC sensor can detect tobramycin accurately and efficiently. In this work, A “signal-off” photoelectrochemical aptasensor was proposed for the ultrasensitive detection of tobramycin. Different from other common n -type semiconductors, p-type semiconductor CuInS 2 was used as the photocathode material in this sensor construction, which had strong anti-interference ability and reduced the occurrence probability of the false signal. Moreover, the compound of gold nanoparticles and CuInS 2 increased the stability of the photocathode. In the presence of tobramycin, it can be well recognized by specific aptamers mounted on the electrode surface, which resulted in decrease of photocurrent. Under optimal conditions, the developed sensor demonstrated in the linear range of 1 pM–100 nM with a low detection limit of 0.59 pM. Furthermore, our strategy achieved high sensitivity, high selectivity, accurately and successfully detected tobramycin in milk and lake water, providing an accurate and effective method for its detection.