A label-free photoelectrochemical aptamer sensor based on in situ Ag2S quantum dot-sensitized BiOI/CdWO4 heterojunction for detection of ochratoxin A.

[Display omitted] • BiOI/CdWO 4 with large specific surface area was synthesized by hydrothermal method. • The combination of aptamers and new materials improves the performance of aptamer-based sensors significantly. • A novel label- free PEC aptamer sensor for the detection of ochratoxin A was developed. • The photocurrent signal of BiOI/CdWO 4 could be effectively enhanced by in-situ growth of Ag 2 S quantum dots. • The photoelectrochemistry aptamer sensor has the advantages of high sensitivity, strong stability, strong selectivity, low detection limit and wide detection range. Ochratoxin A (OTA) is a kind of mycotoxin. It widely exists in all kinds of mammals and has teratogenicity and cytotoxicity. In this paper, a label-free photoelectrochemical (PEC) aptamer sensor based on bismuth oxyiodide/cadmium tungstate (BiOI/CdWO 4) was designed to detect OTA. The BiOI/CdWO 4 heterojunction is an excellent optoelectronic active material with remarkable chemical stability. AgNO 3 and Na 2 S were selected to grow in situ to form Ag 2 S quantum dots, which were sensitized to enhance the absorption of visible light and promote the generation of photocurrent. In this system, with the increasing of OTA concentration, the photoelectric signal intensity reduces as the specific binding with aptamer. When the concentration of OTA is between 0.01 ng/mL and 50.00 ng/mL, the linear equation is I (μA) = 48.95 – 10.276 lg c (c OTA , ng/mL), R2 = 99.281, and the detection limit is 0.823 pg/mL. The newly designed PEC aptamer sensor has exceptional stability, sensitivity, and reproducibility, making it capable of detecting OTA effectively and sensitively. [ABSTRACT FROM AUTHOR]