A sustainable viscosity-sensitive isoliquiritigenin-based molecular sensor for liquid food safety inspection

Abstract

A non-invasive and effective viscosity inspection method during the liquid deterioration process needs to be developed urgently. To develop novel approaches to eliminate or reduce the substantial use of organic solvents and toxic reagents from the preparation procedure, we developed a natural product extracted from licorice, isoliquiritigenin (ILG), as an activatable molecular sensor for monitoring liquid microenvironmental viscosity alterations for metamorphic extent determination. The method displayed rapid detection, high sensitivity, simple operation, and visual result presentation. The sensor comprised a phenol donor and carbonyl acceptor, and displayed a typical twisted intramolecular-charge transfer (TICT) feature, with good photostability, selectivity, and adaptability in various commercial liquids. With the aid of isoliquiritigenin, the thickening effects of liquid thickeners can be captured. More importantly, isoliquiritigenin was explored to visualize the viscosity variations in the liquids at the spoilage stage, and it was found that the viscosity level in microenvironments is highly dependent on the liquid food spoilage period. It is noticeable that this approach can facilitate the continued perfection of molecular tools obtained from natural products for food quality and safety inspection.