Defective UIO66 metal-organic framework nanoparticles assisted by cascade isothermal amplification technology for the detection of aflatoxin B1.

Aflatoxin B1 (AFB1) exhibits significant toxicity and pose a serious threat to food safety, environmental hygiene, and public health even in trace amounts. Hence, the development of a rapid, accurate, and sensitive detection technology has become a pivotal aspect of ensuring control standards. In this study, we introduce the UIO66 and two defective dichloroacetic acid@UIO66 (DCA@UIO66, DU) metal-organic framework nanoparticles, named DU1 and DU2, characterized by different defect levels. It is noteworthy that DU1 exhibits superior DNA sensing capability compared to UIO66 and DU2. With a fluorescence quenching efficiency of 92.66 % and a recovery efficiency of 1256.75 %, DU1 demonstrates the substantial potential in the detection field. Furthermore, we employ cascade isothermal amplification to assist DU1-mediated fluorescence sensors in detecting AFB1. AFB1 is efficiently identified through an aptamer competition process facilitated by magnetic nanoparticles, which initiates the exponential amplification triggered rolling circle amplification reaction, and converts trace amounts of toxin signal into a large number of long single-stranded DNA molecules. Upon recognition of the amplification product by the fluorescent probe on DU1, a more stable double-stranded DNA is formed and leaves the surface of DU1, leading to a significant change in fluorescence intensity. This method exhibits acceptable sensitivity, with a detection limit of 0.09 pg mL^-1 and a wide detection range spanning from 0.2 pg mL^-1 to 20 pg mL^-1. Additionally, this assay exhibits satisfactory specificity and high accuracy in practical sample applications. Our proposed method offers a solid theoretical framework and technical backing, thereby facilitating the establishment of a new generation of mycotoxin detection standards.