A novel label-free electrochemical aptasensor for sensitive and selective detection of microplastics based on split gRNA with CRISPR/Cas12a-mediated cascade strand displacement

Microplastic (MP) pollution has attracted worldwide attention due to its harmful effects on human health and ecosystems. Herein, we develop a novel label-free electrochemical biosensor for sensitive and selective detection of MP based on split gRNA with CRISPR/Cas12a (SCas12a)-mediated cascade strand displacement and an aptamer (termed as CRISPR-MP). Within the CRISPR-MP system, the target polyvinyl chloride (PVC)/polystyrene (PS) triggers the SCas12a-mediated cascade strand displacement, and then activates the DNase activity of SCas12a. Upon cleaving the DNA probe of the G-quadruplex/hemin complex on the gold electrode, the active Cas12a triggers a decrease in the electrochemical signal.This electrochemical aptasensor shows a detection limit of 37 ng/mL of PVC and 45 ng/mL of PS, respectively. The developed CRISPR-MP system expands the utility of the CRISPR for MP detection and exhibits significant promise in protecting human health and monitoring the environment.