Double-network composites based on inorganic fillers reinforced dextran-based hydrogel with high strength.

The biodegradable hydrogels with a 3D network structure have potential applications in bone tissue engineering. Here, inspired by natural bone, the novel organic-inorganic composites (GelMPC-x) with high compressive strength are designed via adding magnesium oxide/calcium dihydrogen phosphate (MPC) powders into the oxidized dextran/gelatin (OD/Gel) hydrogel. GelMPC-x composites can trigger the gelation of OD/Gel hydrogel through an acid-alkaline reaction between magnesium oxide and calcium dihydrogen phosphate, thus forming an organic-inorganic double network. The cross-linked network between oxidized dextran and gelatin, and the multiple weak interactions between OD/Gel hydrogel and MPC enable the composites to have remarkable compressive strength (77-652 kPa) at the strain of 44 %. More importantly, the composites with appropriate MPC content possess superior injectability, high porosity, and excellent cytocompatibility. This work provides guidelines for the preparation of oxidized dextran-based composite hydrogels with enhanced mechanical performance.

Developing a novel magnesium calcium phosphate/sodium alginate composite cement with high strength and proper self-setting time for bone repair.

In this work, novel magnesium calcium phosphate/sodium alginate composite cements were successfully fabricated with a proper setting time (5-24 min) and high compressive strength (91.1 MPa). The physicochemical and biological properties of the cement in vitro were fully characterized. The composite cements could gradually degrade in PBS as the soaking time increase, and the weight loss reached 20.74% by the end of 56th day. The cements could induce the deposition of Ca-P layer in SBF. Cell experiments proved that the extracts of the composite cements can effectively promote the proliferation and differentiation of the mouse bone marrow mesenchymal stem cells (MSCs). These preliminary results indicate that the magnesium calcium phosphate/sodium alginate composite cements could be promising as potential bone repair candidate materials.