Double network composite scaffolds based on oxidized dextran/gelatin hydrogel and magnesium calcium phosphate cement

Magnesium is the fourth most abundant mineral in the human body and plays a significant role in bone growth and development. However, the precise role of magnesium ions is still considerably debated for bone tissue engineering. Here, the biomimetic composite (GelMCPC-x) scaffolds are produced by adding oxidized dextran/gelatin (OD/Gel) hydrogels and magnesium calcium phosphate cement (MCPC) that consisting of magnesium oxide (MgO), calcium dihydrogen phosphate, and β-tricalcium phosphate. The OD/Gel hydrogel provides the 3D network structure for the biomimetic scaffold. The addition of β-TCP affects the existence type of magnesium ions and MgO content in the biomimetic scaffolds. The MgO hydrated acts as an interacting site between inorganic and organic phases, while the sub-micron MgO particles function as a physical filling, both synergistic improving the compression strength of scaffolds through the chemisorption and physisorption. Our study suggests that the synergy between Gel and MgO actively controls for the nucleation site, and the calcium and magnesium ions provide the growth environment for apatite in vitro. When incorporated with 11 wt% of MgO, the GelMCPC-x composites have high compressive strength (5.3 MPa) and excellent osteogenic differentiation ability. This study provides guidelines for developing magnesium-based biomimetic scaffolds used in non-load-bearing bone.