Light-Responsive\nSmart Nanoliposomes: Harnessing the\nAzobenzene Moiety for Controlled Drug Release under Near-Infrared\nIrradiation

The azobenzene moiety is an intriguing structure that\ndeforms under\nUV and visible light, indicating a high potential for biomedical applications.\nHowever, its reaction to UV radiation is problematic because of its\nhigh energy and low tissue penetration. Unlike previous research on\nazobenzene structures in photoresponsive materials, this study presents\na novel method for imparting photostimulation-responsive properties\nto liposomes by incorporating the azobenzene moiety and extending\nthe light wavelength with up-conversion nanoparticles. First, the\nazobenzene structure was incorporated into a phospholipid molecule\nto create Azo-PSG, which could spontaneously form vesicle assemblies\nin aqueous solutions and isomerizes within 1 h of light exposure.\nFurthermore, orthogonal up-conversion nanoparticles with a core–shell\nstructure were created by sequentially growing lanthanide rare earths\nin the shell layer, which efficiently converts near-infrared light\ninto ultraviolet (400 nm) and blue-green (540 nm) light. Combining\nthese core–shell structured up-conversion nanomaterials with\nAzo-PSG molecules resulted in the creation of a near-infrared light-responsive\nsmart nanoliposome system. Under near-infrared light irradiation,\nUCNPs emit UV and blue-green light, causing conformational changes\nin Azo-PSG molecules that allow drug release within 6 h. The reversible\nstructural shift of Azo-PSG in response to light stimulation holds\nenormous promise for improving drug release techniques. This novel\ntechnique also expands the usage of UV-responsive compounds beyond\ntheir constraints of low penetration and high biotoxicity, allowing\nfor rapid medication release under NIR light.