A “one-to-multiple” gold nanoparticle-enhanced CRISPR/Cas12a (AuNP-CRISPR) immunosensor for the sensitive detection of enrofloxacin

Sensitive and accurate detection of enrofloxacin (ENR) residues is essential for food safety. Herein, a competitive immunosensor was developed for the detection of ENR, using a gold nanoparticle (AuNP)-enhanced CRISPR/Cas12a system. In this method, bovine serum albumin-ENR- and single-stranded DNA-modified AuNPs (AuNPs-BSA-ENR/ssDNA) was used to act as both a competitor and CRISPR/Cas12a activator. The use of AuNPs-BSA-ENR/ssDNA helped transduce the target recognition information to the cleavage activity of the CRISPR/Cas12a system. Moreover, benefiting from the high ssDNA loading capability of AuNPs, it enabled one-to-multiple CRISPR/Cas12a activation. The synergetic signal amplification from AuNPs and the CRISPR/Cas12a system guaranteed the sensitivity of this method with a limit of detection of 1 ng/mL. Its feasibility for the detection of food and environmental samples was also investigated with recovery rates ranging from 91.0% to 115.2%. The developed immunosensor offered a promising alternative for ENR detection.