Evaluating Potential of Sr-Doped Bioactive Borosilicate Glasses in Improving Bioactivity and Corrosion Resistance of SS-316L Implants

Abstract The pursuit of improved implant materials for biomedical applications has prompted the development of hybrid inorganic-organic sol-gel methods to coat SS-316L implants. This study focuses on enhancing corrosion resistance and bioactivity through the integration of bioactive particles, particularly investigating the versatility of silicate-based bioactive glasses. By manipulating the chemical composition, especially through the incorporation of strontium (Sr), this research aims to control dissolution rates and bioactivity properties. A series of bioactive borosilicate glasses with increasing Sr concentrations were synthesized using a quick alkali sol-gel method. These glasses underwent in vitro testing with simulated body fluid (SBF) to evaluate their bioactive behavior concerning escalating Sr content. X-ray diffraction (XRD) analysis revealed the emergence of hydroxyapatite (HA) alongside a presence of calcite phase (CaCO3) after 7 days. Notably, scanning electron microscopy (SEM) showcased the presence of HA and calcite crystals. However, at higher Sr concentrations (Sr = 6, 8 mol %), the formation of calcite was significantly suppressed, potentially due to the larger ionic size of Sr hindering the movement and release of other ions required for calcite formation. Based on these outcomes, the Sr-6 glass was selected for coating SS-316L substrates using a sol-gel dip coating method, successfully achieving a 1µm thick bioactive layer. Fourier-transform infrared (FTIR) studies confirmed the formation of a bioactive layer on the surface, demonstrating its capability to form HA. Electrochemical tests conducted illustrated the protective behavior of the coating, markedly enhancing the corrosion resistance of SS-316L plates. This research highlights the potential of Sr-doped bioactive glass coatings to not only improve the corrosion resistance of SS-316L implants but also promote bioactivity, offering a promising avenue for advanced implant materials in biomedical applications. The tailored chemical composition of these glasses holds significant promise in fine-tuning properties critical for implant success, presenting avenues for further exploration and development in the field of biomaterials for medical devices.