Low-temperature sintered boron-doped S53P4 bioactive glass scaffolds fabricated by robocasting

This study investigates boron-doped S53P4 bioactive glass (BG) scaffolds fabricated via robocasting in the context of bone regeneration strategies by comparing their mechanical performance and bioactive behavior to undoped S53P4 BG scaffolds. Three-dimensional scaffolds with grid-like macro architectures were fabricated using gelatin-based composite inks containing S53P4 BG and 10 wt.% boron-doped S53P4 BG (S53P4_10B). The scaffolds were sintered at optimized temperatures (900°C for S53P4 and 615°C for S53P4_10B), resulting in an average volumetric shrinkage of 33 vol%. Both scaffold types exhibited high porosity (∼71%) with pore sizes of 584 ± 7 µm (S53P4) and 608 ± 25 µm (S53P4_10B). Compressive strength values of 3.3 ± 1.7 MPa and 1.5 ± 0.4 MPa were respectively measured for S53P4 and for S53P4_10B BG scaffolds. Soaking in simulated body fluid for 14 days resulted in complete surface coverage with calcium-phosphate-rich phases, indicating high bioactivity. Antibacterial tests revealed that while crystallization reduced the inhibition zone of S53P4 scaffolds, S53P4_10B scaffolds exhibited significant antibacterial activity against E. coli and S. aureus. Cytocompatibility tests using MG-63 and ST-2 cell lines confirmed that scaffold extracts at concentrations ≤1% w/v were noncytotoxic. These results show that boron-doped BG scaffolds possess bioactivity, antibacterial efficacy, and cytocompatibility, and suggest that their mechanical performance can be further tuned through scaffold design and sintering conditions.