Inhibitor-Regulated Cas12a Activation Enables Highly Sensitive and One-Pot Detection of Drug-Resistant Genes in River Water

Monitoring environmental drug-resistance genes (DRGs) plays a pivotal role in preventing the transmission of antimicrobial resistance, thereby reducing public health risks. In this study, a one-pot recombinase polymerase amplification (RPA)/clustered regularly interspaced short palindromic repeat (CRISPR) assay was developed for monitoring DRGs in river water. To overcome compatibility challenges between RPA and CRISPR systems, four glycosaminoglycans (heparin sodium, nadroparin calcium, dalteparin sodium, and chondroitin sulfate A sodium salt) with different molecular weights or negative charge density were evaluated as Cas-enzyme activity modulators. Among them, heparin sodium with the high molecular weight and high strong negative charge density exhibited the best performance in the one-pot DRG detection assay. In the system, CRISPR-Cas12a activity was temporarily inhibited during the RPA amplification phase. When sufficient amplicons were accumulated, Cas12a was activated for signal readout, thereby achieving orderly coupling and precise control of both reactions. To further simplify and improve the reliability of environmental DRG monitoring, a pretreatment method that can eliminate nucleic acid extraction was developed and integrated with the inhibitor-controlled one-pot platform. This assay achieved high sensitivity and specificity when it was applied to river samples, matching the performance of qPCR. The developed assay is simple to operate, has high sensitivity, and is widely adaptable, providing a robust tool for rapid antimicrobial resistance surveillance and exhibiting promise for public health management applications.