Photoelectrochemical immunoassay of aflatoxin B-1 in foodstuff based on amorphous TiO2 and CsPbBr3 perovskite nanocrystals

摘要

Aflatoxin B-1 (AFB(1)) pollution is one of the most serious problems for food safety. In this paper, a split-type photoelectrochemical (PEC) immunoassay was designed for sensitive detection of AFB(1) in foodstuffs by using amorphous TiO2 with all-inorganic perovskite CsPbBr3 nanocrystals (CsPbBr3/a-TiO2). The a-TiO2 layer not only improved the stability of CsPbBr3 nanocrystals, but also facilitated charge transfer, which resulted in the increasing photocurrent of the nanocomposites. Initially, a competitive-type enzyme immunoreaction was executed on a high-binding microplate between the analyte and alkaline phosphatase (ALP)-labeled AFB(1)-bovine serum albumin (AFB(1)-BSA) conjugate. Accompanied by the formation of the immunocomplex, the carried ALP triggered enzymatic hydrolysis to generate ascorbic acid (AA, as an electron donor) for increasing the photocurrent of the CsPbBr3/a-TiO2-modified electrode. Coupling with the competitive enzyme immunoassay, the photocurrent of the modified electrode decreased with the increase of target AFB(1) concentration in a dynamic working range from 0.01 ng mL(-1) to 15 ng mL(-1) with a limit of detection (LOD) of 2.8 pg mL(-1) under optimum conditions. Furthermore, the photoelectrochemical immunoassay was also utilized to detect AFB(1) in peanut and corn samples, giving acceptable accuracy in comparison with the referenced AFB(1) enzyme-linked immunosorbent assay (ELISA) method.