From tongue to eye: A biomimetic colorimetric sensor for umami substances based on taste receptor and plasmonic gold nanoparticles.

Taste perception plays a crucial role in human survival and food quality assessment. Traditional methods for detecting taste substances suffer from limitations such as complex instrumental analysis and subjective evaluation, highlighting the need for developing simple and quantitative methods. Biomimetic sensors that mimic biological sensation to achieve taste evaluation while ensuring objective quantification and high sensitivity have emerged as a promising strategy. In this study, we designed a biomimetic colorimetric sensor based on plasmonic gold nanoparticles (AuNPs) and taste receptors. The Venus Flytrap domain (VFT) of the umami receptor T1R1, expressed heterologously in Escherichia coli, served as the recognition element to specifically recognize the umami substances. Hydrogen bonding interactions between the receptor and umami substances affected the charge balance on the surface of AuNPs, and the localized surface plasmon resonance (LSPR) properties of AuNPs enabled the quantitative detection with visible readout. Through the surface growth of AuNPs, we modulated the spacing between the receptor and AuNPs, thereby amplifying the signal for highly sensitive detection of sodium glutamate (MSG) with high selectivity and a detection limit of 0.0293 mM. Molecular docking results revealed multiple key binding sites between MSG and T1R1-VFT, contributing to its high affinity for the receptor. This biomimetic sensor was applied to detection in real food samples, demonstrating good specificity and stability. This study provides a promising approach for taste detection that holds great potential in food quality inspection and monitoring of food freshness.