Highly sensitive Escherichia coli detection via cell surface in situ cytocompatible ATRP

Foodborne pathogens, including bacteria, viruses, fungi, and parasites, commonly cause disease outbreaks through contaminated food or water. Escherichia coli (E. coli) tends to induce severe illnesses like hemorrhagic colitis and hemolytic uremic syndrome. To address detection challenges, lectins, natural glycoproteins isolated from plants, animals, or microorganisms, demonstrate unique advantages through their specific binding to carbohydrate moieties on pathogen surfaces. This biomolecular recognition mechanism establishes lectins as ideal bioreceptors for developing biosensing platforms targeting foodborne pathogens. In this study, a fluorescent sensor that mediates atom transfer radical polymerization (ATRP) through Concanavalin A (ConA) was developed. This sensor utilizes ConA's ability to capture pathogens and E. coli's ability to catalyze ATRP to identify E. coli. First, ConA is modified onto magnetic beads for initial capture, followed by modification of 2-bromoisobutyryl bromide (BIBB) onto the surface of captured E. coli for subsequent ATRP. If the pathogen captured by ConA is not E. coli, the subsequent ATRP cannot proceed normally, and the sensor cannot generate a fluorescent signal. Under optimal conditions, this sensor demonstrated good linearity from 1.00 × 10² to 1.00 × 10⁷ CFU/mL. The limit of detection has gone down to 8 CFU/mL. This solution has the advantages of high sensitivity, low cost, and easy operation compared to traditional solutions for bacteria detection, which provides an efficient, stable, and sensitive solution for the detection of E. coli.