Photoelectrochemical aptasensor for sensitive detection of tetracycline in soil based on CdTe-BiOBr heterojunction: Improved photoactivity enabled by Z-scheme electron transfer pathway.

Exploring effective methods for tetracycline (TC) detection in soil has great significance because of its emerging environmental problem and increasing threat to soil quality and general public health worldwide. In this work, a sensitive photoelectrochemical (PEC) aptasensor toward TC detection was designed and constructed based on an efficient photosensitive material of Z-scheme CdTe-BiOBr heterojunction. Due to the sensitization of CdTe quantum dots (QDs) on the BiOBr nanoflowers, the photocurrent intensity of the CdTe-BiOBr heterojunction was enhanced about 5.0-fold and 8.0-fold than that of pure BiOBr and CdTe under visible-light irradiation, which was attributed to the low electron-hole combination efficiency, high visible light utilization efficiency, and high carrier density of the heterojunction. On the merits of the excellent PEC activity of the CdTe-BiOBr and the specificity of the aptamer, the proposed PEC aptasensor has the advantages of satisfying linear range (from 10 to 1500 pM), low detection limit (9.25 pM), good selectivity, and reproducibility. In addition, acceptable accuracy was obtained for TC detection in real soil sample, giving acceptable accuracy in comparison with the referenced high-performance liquid chromatography-diode array detector method, revealing a promising avenue for accurate and ultrasensitive estimation of other kinds of contaminants in the broad field of analysis.