Cutting-Edge Exploration of a Molecularly Imprinted Polymer-Coupled Electrochemiluminescence Mechanism Based on Organic Cation Side-Chain Construction for the Identification and Detection of Escherichia coli O157: H7.

In this paper, an organic semiconductor bacterial biosensor was developed for selective detection of facultative anaerobic Escherichia coli O157: H7, which combines electrochemiluminescence (ECL) and bacterial imprinted polymer technologies. Fe2+ and Mn2+ were used to prepare irregular nanocluster ECL emitters (Fe-Mn NCs) via Cu2O, which served as excellent catalysts in the cathodic coreactant (K2S2O8) reaction system, to enhance the ECL signal intensity. Through electropolymerization, the cationic side chains of functional monomers could bind to proteins (such as cytochrome proteins) on the cell membrane of E. coli O157: H7 under aerobic conditions, and transfer to the interior of E. coli O157: H7 and participate in the cyclic regeneration of nicotinamide adenine dinucleotide, which greatly amplifies the detected ECL signal and accelerates the consumption of oxygen by the respiratory chain. When oxygen was consumed, lactic acid was produced by bacteria during the low-oxygen process, in which E. coli O157: H7 can cause a change in the direction of electron flow, resulting in a reduction in the production of SO4•- and a significant decrease in the ECL signal. And when oxygen was readded to the system, the ECL signal recovers or becomes even stronger, where the mechanism of action of cationic semiconductors in this system had been well elucidated. This sensor has a good linear relationship in the range of 101-108 CFU/mL, with a detection limit of 2.29 CFU/mL (S/N = 3), which offers a new detection method for foodborne pathogens, as well as a rapid and accessible identification tool for different types of microorganisms.