Molecularly imprinted Photoelectrochemical sensor for Escherichia coli based on Cu:ZIF-8/KZ3TTz heterojunction

Abstract

Herein, a signal stable molecularly imprinted photoelectrochemical (MIP-PEC) sensing platform was designed to sensitively detect Escherichia coli by incorporating polythiophene film with Cu: ZIF-8/KZ3TTz heterojunction. Attributed to the formation of a staggered type II heterostructure between KZ3TTz and Cu: ZIF-8 semiconductors, the Cu: ZIF-8/KZ3TTz heterojunction exhibited stable and significant cathode PEC response. Impressively, selective MIP film was grown on the surface of Cu: ZIF-8/KZ3TTz/GCE by electro-polymerization of 2,2-Dimethyl-5-(3-thienyl)-1,3-dioxane-4,6-dione (DTDD) in the presence of E. coli. After removing E. coli, more electrons were transferred to the electrolyte solution through the imprinting cavity on the MIP film, which was eliminated by O₂ in the electrolyte, causing further enhancement of the cathode PEC response. On the contrary, when the imprinted cavity was filled with E. coli, the cathodic PEC response gradually decreased due to steric hindrance effect. The sensor showed excellent linearity in the range of 10¹ to 10⁸ CFU/mL with a detection limit of 4.09 CFU/mL (S/N = 3). This strategy offered a novel approach for pathogenic bacteria detection in food safety and environmental monitoring.

Keywords: Escherichia coli; Heterojunction; Molecular imprinting polymer; Nanocomposites; Photoelectrochemical.