A Physically Cross-Linked Sodium Alginate–Gelatin Hydrogel with High Mechanical Strength

Hydrogels constructed from pure biomacromolecules with multifunctions of good mechanical performances, ionic environmental stability, self-healing, biocompatibility, and ionic conductivity are desirable but remain as a challenge. In this work, hydrogels composed of pure biomacromolecules of gelatin and sodium alginate were constructed through a simple repeated acid soaking–drying–swelling process. The obtained hydrogel with a physically cross-linked interpenetrated network of gelatin and sodium alginate contained 79% water and had a relatively high fracture tensile stress and strain of 0.46 MPa and 2.4, respectively. As the gel was cross-linked with a hydrogen bond and alginic acid, it exhibited good stability in a physiological saline solution. Furthermore, the gel exhibited good biocompatibility, self-healing properties, and ionic conductivity, demonstrating its excellent potential for applications in biomedical materials and biosensors.