Development of Gelatin-Silk Fibroin Hydrogel Incorporated with Strontium-Doped Bioglass for Bone Tissue Regeneration

Abstract

Silk fibroin (SF) is a versatile biomaterial widely explored in tissue engineering due to its exceptional structural integrity, biocompatibility, and controllable degradation. Gelatin, derived from collagen, contains RGD (Arg-Gly-Asp) motifs that enhance cell adhesion, proliferation, and extracellular matrix deposition. Several bioinspired hydrogels present promising solutions for bone and cartilage regeneration, offering minimally invasive administration and adaptability to irregular defect sites. However, optimizing their degradation profile is critical, as it influences cellular infiltration and new tissue formation. Traditional hydrogels often lack tunable degradation and mechanical strength, limiting their efficacy in bone repair. Addressing this, our study develops SF based hydrogel with adjustable degradation rates, tailored to match bone healing dynamics. To enhance osteogenic potential, strontium-doped bioactive glass (Sr-BG) particles are incorporated into the SF hydrogel matrix. Sr-BGs release strontium ions that promote osteoblast activity and inhibit osteoclast function, stimulating bone growth and mineralization. Comprehensive physicochemical characterization confirmed the effective formation of Sr-BG particles. Dynamic Light Scattering (DLS) analysis revealed an average particle size of 287.4 ± 34.25 nm at pH 7.0, while the zeta potential was measured as -14.9 ± 2.76 mV at pH 7.4, indicating moderate colloidal stability and uniform dispersion. FTIR, XRD, SEM, and EDX analyses further validated the incorporation of Sr-BG into the SF matrix. FTIR spectra displayed characteristic amide I, II, and III peaks of SF along with Si-O-Si and Sr-O vibrations, confirming bioglass integration. EDX analysis revealed elemental peaks corresponding to Si, Ca, P, O, and Sr, with strontium constituting approximately 2.94 wt%, confirming effective doping and homogeneous dispersion within the hydrogel matrix. SEM images showed a highly porous and interconnected architecture, favourable for nutrient diffusion and cellular infiltration. Mechanical, rheological, and degradation studies showed enhanced mechanical strength, viscoelastic stability, and controlled degradation behaviour. Furthermore, biological studies, including in vitro cytocompatibility and in vivo bone regeneration assays, will be performed to evaluate the osteogenic performance of the developed system.