A photoelectrochemical aptasensor of ciprofloxacin based on BiOCl/BiOCl heterojunction.

A photoelectrochemical (PEC) aptasensor was designed and constructed by BiOCl/BiOCl heterojunction as a photoelectric active material for realizing the determination of trace ciprofloxacin (CIP) in water. Compared with BiOCl, BiOCl/BiOCl heterojunction possessed the improvement of light harvesting and the enhancement of photocurrent signal. The formation of heterojunction between BiOCl and BiOCl can accelerate the transportation efficiency and inhibit the recombination rate of photoinduced carriers. Based on the excellent PEC performance, CIP aptamer was introduced on the modified BiOCl/BiOCl/indium tin oxide (ITO) electrode for fabricating a PEC aptasensor. Owing to the combination between aptamer and CIP, CIP-aptamer complex can block the transfer of charge, leading to the reduction of photocurrent response. The PEC aptasensor possessed high sensitivity with a wide detection range (5.0~1.0 × 10 ng L) and a low detection limit (1.67 ng L, S/N = 3). The PEC aptasensor with good selectivity and reproducibility has been applied to the determination of CIP in water.