Aptamer against Aflatoxin B1 Obtained by SELEX and Applied in Detection

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.

Current developments of SELEX technologies and prospects in the aptamer selection with clinical applications

Aptamers are single-stranded oligonucleotide sequences capable of binding to specific ligands with high affinity. In this manner, they are like antibodies but have advantages such as lower manufacturing costs, lower immunogenicity, fewer batch-to-batch differences, a longer shelf life, high tolerance to different molecular milieus, and a greater number of potential targets. Due to their special features, they have been used in drug delivery, biosensor technology, therapy, and diagnostics. The methodology that allowed its production was the "Systematic Evolution of Ligands by Exponential enrichment" (SELEX). Unfortunately, the traditional protocol is time-consuming and laborious. Therefore, numerous variants with considerable optimization steps have been developed, nonetheless, there are still challenges to achieving real applications in the clinical field. Among them, are control of in vivo activities, fast renal filtration, degradation by nucleases and toxicity testing. This review focuses on current technologies based on SELEX, the critical factors for successful aptamer selection, and its upcoming biomedical and biotechnological applications.

Improvement of the sensitivity of lateral flow systems for detecting mycotoxins: Up-to-date strategies and future perspectives

Mycotoxins are dangerous human and animal health-threatening secondary fungal metabolites that can be found in various food and agricultural products. Several countries have established regulations to restrict their presence in food and agricultural products destined for human and animal consumption. Consequently, the need to develop highly sensitive and smart detection systems was recognized worldwide. Lateral flow assay possesses the advantages of easy operation, rapidity, stability, accuracy, and specificity, and it plays an important role in the detection of mycotoxins. Nevertheless, strategies to comprehensively improve the sensitivity of lateral flow assay to mycotoxins in food have rarely been highlighted and discussed. In this article, a comprehensive overview was presented on the application of lateral flow assay in mycotoxin detection in food samples by highlighting the principle of lateral flow assay, presenting a detailed discussion on various analytical performance-improvement strategies, such as the development of high-affinity recognition reagents, immunogen immobilization methods, and signal amplification. Additionally, a detailed discussion on the various signal analyzers and interpretation approaches was provided. Finally, current hurdles and future perspectives on the application of lateral flow assay in the detection of mycotoxins were discussed.