A sensitive and stable visible-light-driven photoelectrochemical aptasensor for determination of oxytetracycline in tomato samples

Sensitive detection of oxytetracycline (OTC) has attracted increasing attention worldwide due to the relationship between food safety and human health problems. In this work, a visible-light-driven photoelectrochemical (PEC) OTC aptasensor was constructed using Bi4VO8Cl/nitrogen-doped graphene quantum dots (Bi4VO8Cl/N-GQDs) nanohybrids as photoactive material and OTC aptamer as identification element. Owing to the well matched heterojunction of Bi4VO8Cl and nitrogen-doped graphene quantum dots (N-GQDs), the photogenerated electron hole pairs could be separated effectively, so that the photocurrent intensity of as-prepared Bi4VO8Cl/N-GQDs nanohybrids was about 7 times higher than pure Bi4VO8Cl and had higher stability. The constructed signal-off PEC aptasensor realized OTC detection in tomato samples with excellent sensitivity, specificity and repeatability. The photocurrent decreased with the increase of OTC concentration in a range from 0.1 nM to 150 nM, and the detection limit was 0.03 nM (S/N = 3). The national standard method was used to compare with our method and the results were consistent.