Reinforcing biopolymer hydrogels with ionic-covalent entanglement hydrogel microspheres

Microscopic hydrogel spheres can be used to improve the mechanical properties of conventional hydrogels. We prepared ionic-covalent entanglement (ICE) hydrogel microspheres of calcium cross-linked gellan gum and genipin cross-linked gelatin using a water-in-oil emulsion-based processing technique. The method was optimized to produce microspheres with number average diameter 4 ± 1 µm. These ICE microspheres were used to reinforce gelatin hydrogels and improve their compressive mechanical properties. The strongest microsphere reinforced hydrogels possessed a compressive mechanical stress at failure of 0.50 ± 0.1 MPa and a compressive secant modulus of 0.18 ± 0.02 MPa.