An effective strategy of designing “turn on” mode-based lateral flow chromatography for rapid detection of aflatoxin B1

Aflatoxin B1 (AFB1) is an extremely toxic food contaminant that has serious effects on human health. In published aptamer-based lateral flow chromatography test strips, the detection results are mostly inversely proportional to the concentration of AFB1, which is a serious violation of intuition. An aptamer sensor based on the "turn on" mode for AFB1 detection has been reported in this paper. In this paper, we use gold nanoparticles (AuNPs) to present colorimetric signals and link capture sequences (SH-poly A-cDNA) to design AuNPs@SH-poly A-cDNA nanoprobes. The test strip relies on AFB1 and AuNPs@SH-poly A-cDNA competing aptamers for rapid detection of AFB1. In the absence of AFB1, the aptamer binds to AuNPs@SH-poly A-cDNA, preventing the cDNA from binding to the complementary fragment of the test line (DNAT), resulting in the disappearance of the red signal. However, in the presence of AFB1, the aptamer binds to AFB1, allowing some AuNPs@SH-poly A-cDNA not bound to the aptamer to be captured by DNAT, leading to the generation of a red signal. Regardless of the presence or absence of AFB1, the poly-A fragment of AuNPs@SH-poly A-cDNA consistently binds to the complementary sequence of the control line (DNAC) and presents a red signal. The detection results are proportional to the concentration of AFB1, which is in line with human intuitions. The development of this test strip provides a novel design idea for the detection of small molecules such as mycotoxins.