IN VITRO EVALUATION OF SILICATE AND BORATE BIOACTIVE GLASS SCAFFOLDS PREPARED BY ROBOCASTING OF ORGANIC-BASED SUSPENSIONS

摘要

Porous three-dimensional scaffolds of silicate (13-93) and borate (13-93B3) bioactive glass were prepared by robocasting and evaluated in vitro for potential application in bone repair. Organic-based suspensions were developed to limit degradation of the bioactive glass particles, and deposited layer-by-layer to form constructs with a grid-like microstructure. After binder burnout, the constructs were sintered for 1 hour at 690 ℃ (13-93 glass) or 560 ℃ (13-93B3 glass) to produce scaffolds (porosity ≈ 50%) consisting of dense glass struts (400 μm in diameter) and interconnected pores of width 300 μm. The mechanical response in compression and the conversion of the scaffolds to hydroxyapatite (HA) were studied as a function of immersion time in a simulated body fluid (SBF). As fabricated, the 13-93 scaffolds showed a compressive strength of 142 ± 20 MPa, comparable to the values for human cortical bone, while the 13-93B3 scaffolds showed a compressive strength of 65 ± 11 MPa, far higher than the values for trabecular bone. When immersed in SBF, the borate 13-93B3 scaffolds converted faster than the silicate 13-93 scaffolds to a calcium phosphate material, but they also showed a sharper decrease in strength. Based on their high compressive strength, bioactivity, and microstructure favorable for supporting tissue ingrowth, the scaffolds fabricated in this work by robocasting could have potential application in the repair of loaded and non-loaded bone.