Visible light-mediated crosslinked methacrylated gellan gum nanocomposite hydrogel: physicochemical characterization and in vivo safety

• Photocrosslinkable methacrylated gellan gum (GGMA)-based hydrogel for cartilage applications. • Comprehensive characterization and assessment of the in vitro and in vivo safety profile of the GGMA nanocomposite. • GGMA nanocomposite shows improved injectability, mechanical properties, and cartilage adhesion. • GGMA nanocomposite is fully biocompatible and exhibits translational potential. Methacrylated gellan gum (GGMA) injectable hydrogels have emerged as promising candidates for cartilage tissue engineering due to their structural similarity to cartilage glycosaminoglycans and the tunability enabled by visible-light photocrosslinking. Incorporating functional nanomaterials represents a promising approach to improve their functionality for cartilage repair. Although several studies have highlighted the in vitro potential of nanocomposite hydrogels, comprehensive evaluations of the in vivo safety of photocrosslinkable hydrogels for clinical use remain limited. Here, we demonstrated that the incorporation of graphene oxide nanoflakes and barium titanate nanoparticles into visible light–crosslinked GGMA hydrogels preserved their shear-thinning behavior while improving mechanical properties and adhesion to cartilage, without affecting lubrication or degradation. In vitro safety, evaluated according to ISO 10993 standards, confirmed the absence of cytotoxicity in human chondrocytes and genotoxic effects both in bacteria and human lymphoblasts. In vivo ISO 10993-compliant assessments (including skin irritation, delayed-type hypersensitivity, acute and subchronic systemic toxicity, and local effects after implantation) confirmed the biocompatibility of GGMA nanocomposites, with no local or systemic adverse effects in both animal sexes. Overall, GGMA-based nanocomposite hydrogels exhibited favorable mechanical and biological properties and a safe in vivo profile, supporting their potential for translational cartilage applications.