2D/2D heterojunction of ZnIn2S4/N-doped graphene nanosheets for off-type high-performance photoelectrochemical aptasensor

Residues caused by the abuse of antibiotics will lead to the resistance of bacteria and harm human health through the food chain. Photoelectrochemical (PEC) aptamer sensing technology has been broadly applied in analysis and detection because of its merits of low cost, fast response, high sensitivity, high affinity, and high specificity. Highly active photosensitive materials are suitable for constructing sensitive ‘signal-off’ type PEC aptasensor. Nitrogen-doped graphene nanosheet-loaded ZnIn2S4 (ZIS/NG) functional material was prepared by a simple one-step solvothermal method. The introduction of NG inhibits the over-assemble of ZIS, forming ZIS/NG 2D/2D Van Der Waals (VDW) heterojunctions. NG cannot only broaden the visible absorption range but accept electrons from ZIS, thus promoting charge separation efficiency. In addition, the as-synthesized ZIS/NG 2D/2D VDW heterojunctions have a good synergy between the two layers, inhibiting electron-hole recombination, improving interfacial charge transfer, and increasing active sites. Hence, the photocurrent of ZIS/NG was significantly higher than that of ZIS. Based on high photocurrent of ZIS/NG, a “signal-off” mode PEC aptasensor was constructed to detect oxytetracycline (OTC), which expressed high sensitivity and selectivity. It can achieve rapid reaction within the linear scope of 1 pmol/L to 5 μmol/L and exhibit relatively low detection limit (0.33 pmol/L). The constructed aptasensor has been applied to detect OTC in chicken with a good recovery.