Design strategies of fluorescent covalent organic frameworks and visual on-site monitoring of food freshness: A state-of-the-art review

Abstract

Owing to the high demand for fresh food and its perishability and fast inventory turnover, real-time monitoring of food freshness has gradually attracted widespread attention. The development of sensors that can intelligently monitor the freshness of food in real time can not only help consumers make optimal decisions and reduce economic losses but also make important contributions to ensuring the nutrition and safety of food. Covalent organic frameworks (COFs) are a class of highly crystalline organic porous materials with large specific surface areas, high porosities and tuneable structures that can be used to construct platforms for fluorescence sensing. Fluorescent sensors based on COFs have been gradually applied as effective tools for determining food freshness. The aim of this work is to facilitate the development of a more accurate and comprehensive platform for food freshness determination using fluorescent COFs.