Assessment of in-vitro bioactivity, biodegradability and antibacterial activity of polymer-derived 3D printed akermanite scaffolds

Reticulated akermanite (Ca2MgSi2O7) 3D scaffolds were fabricated by direct ink writing of pastes based on a commercial silicone resin and fillers, such as calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)(2)) microparticles, followed by heat treatment at 1100 degree celsius in air. To form liquid phase upon firing and thus promote the ionic interdiffusion, borax (Na2B4O7 center dot 10H(2)O) or hydrated sodium phosphate (Na2HPO4 center dot 12H(2)O) were considered as alternative additives. Although leading to scaffolds with different strength-to-density ratio, the two additives did not lead to substantial differences in terms of biological response. All fabricated ceramics exhibited acellular in-vitro bioactivity upon immersion in simulated-body-fluid (SBF) as well as antibacterial activity against S. aureus and E. coli. Direct contact cell viability test, performed with a stromal-cell line from mouse bone marrow (ST-2 cells), indicated no cytotoxicity of both samples determined by the WST-8 assay.