Thermo-controlled\nWater Microenvironment Inducing\nFluorescence Enhancement of Chalcone Nanohydrogels for Mitochondrial\nTemperature Sensing

Developing aggregation-induced emission (AIE)-based hydrogels\nthat\nexhibit fluorescence enhancement as to thermal properties is an interesting\nand challenging task. In this work, we employed the fluorophore 2′-hydroxychalcone\n(HC), fluorescence properties of which are easily influenced by the\nexcited-state intramolecular proton transfer and twisted intramolecular\ncharge transfer (TICT) effects, to develop a novel type of temperature-sensitive\npolymers, hydroxychalcone-based polymers (HCPs). By controlling the\ntemperature-dependent water microenvironments in HCPs, the intramolecular\nhydrogen bonds between water and HCPs can be regulated, thereby influencing\nthe TICT process and leading to thermo-induced fluorescence enhancement,\nwhich shows a contrary tendency compared to typical AIEgens that always\nexhibit fluorescence attenuation as the thermal energy accelerates\nthe molecular motion. Following the decoration with triphenylphosphine,\nthe resulting polymer P-HCP assembled into nanohydrogels and served\nas a fluorescent probe for intracellular mitochondrial temperature\nsensing.