Sensitive Detection of Chloramphenicol Using Electrochemiluminescence Imaging Based on a DNA Walker Coupled with Nanozyme Quenching Effect

Chloramphenicol (CAP), as a broad-spectrum antibiotic, can combat bacterial infections but can accumulate in the human body through food chains, leading to food safety issues. In this work, a novel electrochemiluminescence (ECL) biosensing strategy utilizing Prussian blue nanozymes (PBZs) to quench the ECL signals of the Tb-Luminol coordination polymer (Tb-Lu CP) was proposed for CAP detection. Tb-Lu CP possessed a unique aggregation-induced electrochemiluminescence (AIECL) property. Moreover, it exhibited significantly more stable and higher ECL signals than that of pure luminol, offering an ideal basis for constructing a stable ECL biosensor. Meanwhile, PBZs possessed superoxide dismutase (SOD)-mimetic, catalase (CAT)-mimetic, and hydroxyl radical (•OH) elimination activities. These properties enabled PBZs to serve as efficient quenchers and achieve ECL signal quenching, with a quenching efficiency exceeding 60%. The ECL imaging biosensor we designed relied on the assistance of exonuclease III (Exo III) and the formation of a DNA walker. This allowed ultrasensitive detection of CAP, featuring a wide linear range from 1.0 pg/mL to 100 ng/mL and a detection limit as low as 0.54 pg/mL. This ECL imaging biosensor provided an alternative approach for highly sensitive and visual CAP detection.