Synergistic effect of MOF@Pt@MOF-B(OH)2 in biosensing platform: The combined action of boronic acid groups and composite MOF applied to dual-mode detection and portable smartphone sensing of bacteria in food

Abstract

Bacterial contamination in food constitutes a grave menace to the global public health. Consequently, the rapid detection of foodborne bacteria is of paramount importance for addressing the increasingly severe challenges. Herein, a multifunctional MOF@Pt@MOF-B(OH)₂ was developed, integrating colorimetric-fluorescence detection and smartphone sensing to create a novel biosensing platform for the detection of Escherichia coli (E. coli) in food. The MOF@Pt@MOF-B(OH)₂ exhibited exceptional enzymatic activity and fluorescence property owing to its composite structure, as well as its ability to recognize bacterial glycoproteins through boronic acid groups. This enabled selective identification of glycosylated sites on the surface of E. coli through covalent interactions, thereby amplifying the detection signal. The colorimetric-fluorescence platform achieved selective detection of E. coli, boasting a detection limit of 2 and 1 CFU/mL within a linear detection range of 1.5 × 10¹–1.5 × 10⁴ CFU/mL. This dual-mode strategy demonstrated remarkable specificity and interference resistance, achieving good recovery rates (91.76 %–108.73 %) in food samples with a relative standard deviation (RSD) below 4.72 %. Additionally, recognizing the importance of portable detection for on-site monitoring, a smartphone-mediated portable detection device was developed for real-time use. This device similarly could detect E. coli with high sensitivity and showed excellent practical application potential, achieving recovery rates from 95.57 % to 98.61 %, with RSD values below 2.56 %. These results fully demonstrated the effectiveness of the sensing platform for detecting E. coli in food.