Rare-earth doped upconversion-photopolymerization hydrogel hybrids for in vivo wound healing

In vivo wound healing stands as a transformative paradigm in the field of tissue repair and regeneration, yet still suffers from a pivotal limitation of inferior penetration depth along with the thermal tissue damage side-effect of photopolymerization hydrogels under conditions of suboptimal light and power. Herein, we propose an upconversion-photopolymerization-driven strategy and synthesize injectable NaYF4:Yb3+,Tm3+@NaYF4:Nd3+,Yb3+ + GelMa (UC-YT@NY + GelMa) hydrogel hybrids to respond to in vivo wound healing. The use of a near-infrared laser with a wavelength of 808 nm, a power density of 1.27 W cm−2 and an irradiation time of 8 minutes resulted in a hydrogel photopolymerization efficiency of up to 96.3%. A comparison with the use of a 980 nm laser under the same conditions shows that our process not only has excellent photopolymerization performance, but also significantly reduces the photothermal effect. Our biocompatible hydrogel hybrids facilitate deep-penetration wound healing at a depth of 3 mm in a mouse model and achieve complete healing in 7 days. This novel interventional therapy provides precise spatiotemporal control over therapeutic agent release, offering high-quality deep-tissue wound healing.