Label-Free Homogeneous Electroanalytical Platform for Pesticide Detection Based on Acetylcholinesterase-Mediated DNA Conformational Switch Integrated with Rolling Circle Amplification.

This study addresses the need for sensitive pesticide assay by reporting a new label-free and immobilization-free homogeneous electroanalytical strategy, which combines acetylcholinesterase (AChE)-catalyzed hydrolysis product-mediated DNA conformational switch and rolling circle amplification (RCA) to detect organophosphorous and carbamate pesticides in a "signal-on" mode. When target pesticides were present, AChE activity was inhibited and could not trigger the following DNA conformational change and the RCA reaction, which results in numerous methylene blue (MB) molecules in a free state, generating a strong electrochemical response. This proposed strategy was highly sensitive for omethoate detection with a detection limit as low as 2.1 μg/L and a linear range from 10 to 10 000 μg/L. Furthermore, this strategy was demonstrated to be applicable for pesticide detection in real samples. Thus, this novel label-free homogeneous electroanalytical strategy holds great promise for pesticide detection and can be further exploited for sensing applications in the environment and the food safety field.