An electrochemiluminescence strategy with proximity ligation triggered multiple catalytic hairpin assembly induced CRISPR/Cas 12a system for analysis of paraquat

Abstract

Paraquat (PQ) as a widely used non-selective herbicides has gained attention in agricultural residue detection and food safety. Herein, a novel quantitative analysis approach for PQ was proposed based on a novel kind of aggregation-induced emission electrochemiluminescence (AIECL) emitters, tetraphenylethylene-luminol (TPE-L) with a small molecule-induced multiple catalytic hairpin assembly (CHA) amplification strategy, the competitive immune reaction and CRISPR/Cas12a system. The target molecule PQ is introduced into a signal cycle, and auxiliary sensitization cycles are constructed by virtue of the cleavage characteristics of the CRISPR/Cas12a system, which realized the multiple utilization of the target by using both cis- and trans-cleavage activities. In addition, the new multiple CHA amplification strategy was attributed to cross-catalytic hairpin assembly caused by the products of the CHA cycle as the initiator chain of the next CHA cycle, realizing the efficient utilization of cyclic products and producing high-efficiency signal amplification. Thus, the ECL biosensor for ultrasensitive analysis of PQ was successfully constructed with a limit of detection of 0.7 pg/mL. Importantly, it could be easily-extended to other small molecules simply by replacing paired antibodies, providing prospects in agricultural residue detection, food safety and related medical applications.