Robocasting of multicomponent sol-gel–derived silicate bioactive glass scaffolds for bone tissue engineering

Abstract

Robocasting is universally recognized as an affordable and reproducible manufacturing strategy to process glass and glass-ceramic materials in the form of highly ordered porous scaffolds for bone tissue engineering (BTE) applications. Nevertheless, while being widely applied to melt-derived bioactive glasses, this technique was seldom implemented with sol-gel materials due to the intrinsic difficulties in producing suitable inks for extrusion and thus, good printing outcomes. The present experimental work describes a new and relatively easy method to manufacture multicomponent sol-gel bioactive silicate scaffolds (oxide system: 47.5SiO2–20CaO–10MgO–10Na2O-10 K2O-2.5P2O5, mol.%) using dried gels as basic material within the ink composition, which allows by-passing intermediate heat treatments that are usually detrimental to the bioactive potential of the material in physiological environment. The scaffolds, exhibiting a total porosity of 81 vol%, were characterized in terms of morphological-compositional features and bioactivity in simulated body fluid (SBF), paying special attention to ion release and surface modifications occurring upon soaking (apatite-forming ability). The compressive strength of the scaffolds (around 5 MPa) was comparable to that of human cancellous bone. Collectively, the results supported the possibility of using robocast sol-gel–derived scaffolds in BTE approaches. Furthermore, a comparison with robocast scaffolds based on a melt-derived glass with the same composition was reported in order to investigate the effect of the synthesis route on the dissolution behavior and morphological features of the final biomaterials.