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 (DNA_T), 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 DNA_T, 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 (DNA_C) 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.