Methacryloylated chitosan hydrogel-mediated polyphenol-Ga/hUCMSC-Exo release platform: Possessing antibacterial,...

Bacterial infections and excessive inflammation frequently arise during titanium-based bone repair endeavors and necessitate intervention. In this study, a methacrylated chitosan (CS-MA) hydrogel encapsulating human umbilical cord mesenchymal stem cell-derived exosomes (Exos) was meticulously coated onto the surface of a metal phenolic network (TA-Ga, composed of tannic acid and Ga³⁺), thereby constructing a multifunctional coating of TA-Ga/CS-MA@Exo with pH-responsiveness on the titanium surface. The coating exhibited commendable hydrophilicity, corrosion resistance, and blood compatibility. Leveraging the antimicrobial attributes of Ga³⁺, this coating exhibited inhibitory rates of (84.66 ± 0.001)% against S. aureus and (67.17 ± 0.02)% against E. coli. Moreover, the coating was capable of modulating the polarization of RAW264.7 cells towards the M2 phenotype, effectively reconfiguring the local anti-inflammatory microenvironment. Concurrently, the coating also significantly facilitated HUVEC migration, lumen formation, and the expression of vascularizing growth factors. Interestingly, the coating significantly enhanced MC3T3-E1 differentiation towards osteoblasts, where the expression level of the key osteogenic gene RUNX2 was increased by approximately 2.94-fold. In vivo, the coating also manifested ideal antimicrobial, anti-inflammatory, angiogenic, and bone repair capabilities, holistically satisfying the intricate demands of infectious bone repair. In conclusion, TA-Ga/CS-MA@Exo furnishes an efficacious and comprehensive resolution for infected bone repair and harbors substantial potential for clinical application.