Construction of dual-mode sensing platforms based on MPC-B(OH)2 nanozyme: Colorimetric/electrochemical detection and portable smartphone sensing for foodborne contaminant detection

Early and portable detection of foodborne pathogens is a key challenge for food safety, as conventional methods suffer from insufficient sensitivity and cumbersome operation. Herein, inspired by cellular compartmentalization, we designed the composite nanozyme MIL-88(Fe)@Pt@COF-B(OH) 2 (MPC-B(OH) 2 ) and constructed a dual-mode biosensing platform with Escherichia coli ( E. coli ) as the model. In this design, a catalytic MIL-88(Fe)@Pt core was encapsulated by a boronic acid-functionalized COF shell, which mimicked a cell membrane to provide specific recognition while optimizing the local microenvironment to enhance peroxidase-like activity, as clarified by density functional theory calculations. Meanwhile, its porous COF layer improved electrochemical performance. This sensor achieved detection limits of 2 and 3 CFU/mL for colorimetric/electrochemical modes, and 7 CFU/mL for on-site detection via a smartphone platform. With excellent selectivity, stability and reliability in real samples, this work provided a new strategy for biomimetic nanozyme design and a practical platform for on-site food safety monitoring.