Near Infrared Light Triggered Release of Biomacromolecules from Hydrogels Loaded with Upconversion Nanoparticles

Using a photosensitive hybrid hydrogel loaded with upconversion nanoparticles (UCNPs), we show that continuous-wave near-infrared (NIR) light (980 nm) can be used to induce the gel-sol transition and release large, inactive biomacromolecules (protein and enzyme) entrapped in the hydrogel into aqueous solution on demand, where their bioactivity is recovered. This study is a new demonstration and development in harnessing the unique multiphoton effect of UCNPs for photosensitive materials of biomedical interest.