Electrochemical biosensor for detecting pathogenic bacteria based on a hybridization chain reaction and CRISPR-Cas12a

In this study, Lba Cas12a (Cpf1) as one of the CRISPR systems from Lachnospiraceae bacterium was coupled with a hybridization chain reaction (HCR) to develop an electrochemical biosensor for detecting the pathogenic bacterium, Salmonella typhimurium. Autonomous cross-opening of functional DNA hairpin structures of HCR yielded polymer double-stranded DNA wires consisting of numerous single-stranded DNAs, which initiated the trans-cleavage activity of CRISPR-Cas12a to indiscriminately cleave random single-stranded DNA labeling electrochemical tags on the surface of the electrode. It led to a variation in the electron transfer of electrochemical tags. The polymer double-stranded DNA of HCR was immobilized on dynabeads (DBs) via the S. typhimurium aptamer and released from DBs. The established method could selectively and sensitively quantify S. typhimurium in samples with detection limits of 20 CFU/mL. Our study provides a novel insight for exploring universal analytical methods for pathogenic bacteria based on CRISPR-Cas12a coupled with HCR.

Automated summary

This study developed an electrochemical biosensor by coupling the CRISPR system with HCR for detecting Salmonella typhimurium. The interaction between DNA wires and CRISPR-Cas12a enabled the detection of electrochemical tags, allowing for selective and sensitive quantification of the pathogenic bacterium in samples. This method provides a novel insight for exploring universal analytical methods for pathogenic bacteria based on CRISPR-Cas12a coupled with HCR.