Preparation and Characterization of the Properties of Atmospheric Plasma-Sprayed Sr/Mg-Doped Bioactive Glass Coatings on Titanium Alloys

Titanium alloys are widely used in clinical settings due to their excellent mechanical properties and biocompatibility. However, the biologically inert surface of titanium alloys limits interfacial bioactivity and bone integration, which may compromise long-term implant stability. Therefore, this study innovatively proposes a synergistic “composition design and process adaptation” strategy. Specifically, borosilicate bioactive glasses (BSBGs) with a high B2O3 content (36 mol%), co-doped with strontium (Sr) and magnesium (Mg), were designed and systematically compared with Sr/Mg-doped silicate bioactive glasses (SBGs). Both glasses were subsequently deposited onto Ti6Al4V substrates using atmospheric plasma spraying. The results showed that the BSBG coating exhibited an initial boron release concentration of up to 116 mg/L but exhibited excellent cytocompatibility, which is likely related to the synergistic regulation of Sr, Mg, and B ions. Moreover, the BSBG coating induced Ca-P compound mineralization within 24 h, significantly faster than the SBG coating, which required a minimum of 3 days, confirming superior biomineralization kinetics. Both coatings achieved a bonding strength of 30 MPa, meeting clinical requirements. In vivo experiments confirmed that the BSBG coating significantly promoted new bone regeneration and implant osseointegration. This work not only delivers experimental validation supporting the implementation of high-boron-content bioactive glass coatings but also provides a practical method for designing rapidly degradable and highly bioactive coatings to facilitate improved osseointegration.