Enhanced bone healing of photothermal hydrogel via mild heat stimulation and Zn2+ release

The loss of alveolar bone has caused heavy burden worldwide. In this paper, we have synthesized photothermal hydrogel with sustained release of Zn2+ and repeated mild heat stimulation. The in situ retention of ZnO microspheres (ZnO-MPs) and polydopamine (pDA) have been achieved by loading into the thermosensitive hydrogel network after injection in the subcutaneous tissue. The hydrogel could reach around 42 °C under near infrared light irradiation (for 6 min). And after 2, 4 and 6 days, the in situ hydrogel was proved still photothermal sensitive. Sustained released Zn2+ and mild heat (for 6 min each) promoted BMSCs cell viability and osteogenic differentiation, and after being implanted into the tooth socket after 14 days, micro-CT, HE and masson staining have illustrated that more newly formed bone tissue was observed in the hydrogel + laser group, compared with that of control. This photothermal hydrogel has demonstrated efficient photothermal effects, drug releasing capacity with promising clinical application potential for bone regeneration in the future.