Photoelectrochemical biosensor based on DNA aptamers and dual nano-semiconductor heterojunctions for accurate and selective sensing of chloramphenicol.

Nanosheets of anatase TiO2 and CdS quantum dots modified with thioglycolic acid (TGA-CdS QDs) were prepared and hierarchically modified on the indium tin oxides (ITO) electrodes. The heterojunction structure is formed to improve the light capture ability and carrier migration, significantly enhancing the sensitivity of photoelectrochemical (PEC) biosensors. Specific DNA sequences labeled with TGA-CdS QDs were placed on the electrodes to prepare a biosensor for the detection of chloramphenicol with ultrahigh selectivity. In addition, the heterojunction structure and the principle of photocurrent signal amplification on the electrode are described in detail. Under the optimal conditions, the photoelectrochemical biosensors showed good reproducibility and stability for chloramphenicol with a linear response in the range 10-10,000 pM and a limit of detection (LOD) of 0.23 pM. Due to the specific recognition of base pairs, the sensor has excellent anti-interference ability in practical applications. An effective method was developed for the accurate detection of antibiotics with far reaching prospects.