Self-replicating catalyzed hairpin assembly for rapid aflatoxin B1 detection

Abstract

Herein, a rapid signal amplified aflatoxin B1 (AFB1) detection system based on self-replicating catalyzed hairpin assembly (SRCHA) has been constructed. In this SRCHA system, trigger DNA was initially blocked and two split trigger DNA sequences were integrated into two hairpin auxiliary probes, H1 and H2, respectively. In the presence of AFB1, the aptamer sequence was recognized by AFB1 and trigger DNA was released, which can initiate a CHA reaction and lead to the formation of a helix DNA H1–H2 complex. Then this complex can dissociate double-stranded probe DNA (F–Q) and the fluorescence signal was recovered. Meanwhile, the two split trigger DNA sequences came into close-enough proximity and a trigger DNA replica was formed. Then the obtained replicas can trigger an additional CHA reaction, leading to the rapid and significant enhancement of the fluorescence signal, and AFB1 can be detected within 15 min with a detection limit of 0.13 ng mL⁻¹. This AFB1 detection system exhibits potential application in the on-site rapid detection of AFB1.