Photoelectrochemical aptasensing of oxytetracycline based on a BiVO4-carboxylated graphene-WO3 Z-scheme heterojunction

A new BiVO4-carboxylated graphene (cG)-WO3 Z-scheme heterojunction was constructed on a fluorine-doped tin oxide (FTO) substrate electrode by ultrasonic mixing and cast-coating for determination of oxytetracycline (OTC). Since cG can absorb visible light and well match with the energy levels of WO3 and BiVO4 to promote the charge separation and transfer, the photocurrent on the BiVO4-cG-WO3/FTO photoelectrode is 4.4 times that on the control BiVO4-WO3/FTO photoelectrode. An amino-functionalized OTC aptamer was fixed on the BiVO4-cG-WO3/FTO photoelectrode by the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide mediated amide reaction, and then hexaammonium ruthenium(III) (Ru(NH3)(6)(3+)) was attached to the OTC aptamer to increase the photocurrent response to the OTC binding. Under the optimized conditions, the photocurrent on the BiVO4-cG-WO3/FTO photoelectrode at 0 V vs SCE was linear with the common logarithm of OTC concentration from 0.01 nM to 500 nM, with a limit of detection of 3.1 pM (S/N = 3). Satisfactory recovery results were obtained in the analysis of real water samples.

Automated summary

A new BiVO4-carboxylated graphene (cG)-WO3 Z-scheme heterojunction was constructed for determination of oxytetracycline (OTC). The photocurrent on the BiVO4-cG-WO3/FTO photoelectrode was 4.4 times higher than that on the control BiVO4-WO3/FTO photoelectrode due to the energy level match and charge separation. By attaching an amino-functionalized OTC aptamer and hexaammonium ruthenium(III) to the BiVO4-cG-WO3/FTO photoelectrode, the photocurrent response to OTC binding was increased.