Microcrystallization-gelation enabled mechanocompatible and antibacterial hydrogels for cartilage repair

Repairing cartilage defects requires biomaterials with mechanical properties similar to native cartilage. However, balancing these properties with biodegradability remains a major challenge. In this study, a degradable antibacterial hydrogel with promising mechanical characteristics was developed for personalized cartilage defect repair. The hydrogel was synthesized using chitosan and gelatin via microcrystallization and gelation, combined with chemical crosslinking facilitated by epichlorohydrin. This method significantly enhanced the mechanical properties of the material, with compressive modulus of the optimal group reaching 0.2 MPa and tensile strength reaching 2.2 MPa, which are comparable to those of human cartilage. The hydrogel maintained its integrity after 50000 compression cycles. With excellent flowability prior to crosslinking, it can adapt to complex cartilage defects. The inclusion of gentamicin provides antibacterial properties, while nano-hydroxyapatite promotes osteogenesis. This hydrogel, with its multiple crosslinking mechanisms, balances mechanical strength, biodegradability, and adaptability, offering a promising solution for repairing infected cartilage defects.