Copper-based carbon dots modified hydrogel with osteoimmunomodulatory and osteogenesis for bone regeneration†

Biomaterials with dual functions of osteoimmunomodulation and bone repair are very promising in the field of orthopedic materials. For this purpose, we prepared copper-based carbon dots (CuCDs) and doped them into oxychondroitin sulfate/poly-acrylamide hydrogel (OPAM) to obtain a hybrid hydrogel (CuCDs/OPAM). We evaluated its osteoimmunomodulatory and bone repair properties in vitro and in vivo. The obtained CuCDs/OPAM exhibited good rBMSCs-cytocompatibility and anti-inflammatory properties in vitro. It also could effectively promote rBMSCs differentiation and the expression of osteogenic differentiation factors from rBMSCs under an inflammatory environment. Moreover, CuCDs/OPAM could induce macrophage phenotype switching (from M1-type macrophages to M2-type macrophages) in vivo, which is beneficial for anti-inflammatory action and presents good osteoimmunomodulation capability to induce a bone immune microenvironment to promote the differentiation of rBMSCs. In conclusion, CuCDs/OPAM hydrogel has dual functions of osteoimmunomodulatory and bone repair and is a promising bone filling and repair material.