Design and characterization of an injectable biohybrid hydrogel based on chitosan/silk fibroin/hyaluronic acid and containing bioactive glass for bone tissue engineering

Bone fractures are one of the most common injuries that usually occur after a blow or severe pressure to the bone. One way to treat and speed up the healing process of bone fractures is to use injectable gels containing suitable ions for repair, at the fracture site. This research focuses on developing an injectable hydrogel made from natural polymers as chitosan (CS), silk fibroin (SF), and hyaluronic acid (HA), combined with bioactive glass (BG) for bone repair. Various hydrogels, including CS hydrogels, CS/SF, CS/SF/HA, and CS/SF/HA containing BG with different component ratios, were prepared. Characterization analyses, including gelation time, FE-SEM, BET, FTIR, swelling, biodegradability, and strength analysis were performed. Calcium ion release from the hydrogel was measured and modeled. Additionally, the cytotoxicity of the prepared hydrogels was assessed using an indirect MTT assay. Results indicated that addition of CS and HA significantly reduced the lengthy gelation time of SF hydrogels to under 5 min. These components also enhanced swelling rate and biodegradability. The CS/SF/HA/BG hydrogel exhibited superior Young’s modulus in compressive strength analysis compared to other formulations. FE-SEM imaging revealed a 3D network structure with interconnected pores in the designed hydrogels. Calcium ion release reached approximately 80% after 7 days, following the Higuchi model for the initial 48 h (describing ion dissolution) and transitioning to the Korsmeyer-Peppas model thereafter (indicating Fickian diffusion). Cytotoxicity analyses confirmed the low toxicity of all tested hydrogel samples. The CS/SF/HA/BG hydrogel is a promising candidate for bone repair. However, further studies in animals and humans are needed to confirm its effectiveness.