Mn2+-activated CRISPR-Cas12a strategy for fluorescence detection of the insecticide carbaryl

This study developed a simple fluorescence method for detecting the insecticide carbaryl using the Mn2+-activated CRISPR-Cas12a system (MACC). Based on the phenomenon that Mn2+ significantly enhances the trans-cleavage activity of Cas12a and the acetylcholinesterase (AChE) catalysis-mediated degradation of MnO2 nanosheets, the Mn2+-activated CRISPR-Cas12a system was utilized for highly sensitive detection of AChE with a detection limit of 0.08 mU/mL. As an inhibitor of AChE, carbaryl was successfully detected through this strategy with a detection limit of 29 nM (5.8 μg/kg), significantly lower than the pesticide residue limits established by the United States (20 μg/kg) and European Union (50 μg/kg). Furthermore, the concentrations of carbaryl in real samples detected by this method exhibited substantial concurrence with those revealed by the classical method, indicating our method's acceptable accuracy and sensitivity. Overall, this study presents a highly sensitive method for detecting AChE activity and the insecticide carbaryl.