CRISPR-Cas12a-regulated photo-ATRP for ultrasensitive detection of lipopolysaccharide.

Lipopolysaccharide (LPS), a primary virulence factor produced by Gram-negative bacteria, demands rapid and ultrasensitive detection for safeguarding food safety and supporting clinical diagnosis. This study developed a novel electrochemical biosensing platform by integrating the programmable recognition of CRISPR-Cas12a with the high-gain signal amplification of photoinduced ATRP. In this mechanism, the binding of LPS to its aptamer regulated Cas12a activity, which controlled an N3-DNA initiator probe. This probe, in turn, guided in-situ photopolymerization via click chemistry, generating a dramatically enhanced signal. The sensor exhibited a linear range from 10 fg/mL to 1 ng/mL with a detection limit of 2.48 fg/mL, along with high selectivity, reproducibility, and stability. Tests in spiked beverage samples showed high recovery rates and strong anti-interference capability. This work not only achieves ultrasensitive LPS detection but also provides a new approach for extending CRISPR-based biosensing to non-nucleic acid targets.