Hybrid direct ink writing of bioglass-calcite-carbon composite scaffolds supported by novel silicone-based emulsions

70S30C (70 mol% SiO2, 30 % CaO) bioglass is one of the most promising bioceramics for bone tissue engineering. We discuss the feasibility of 70S30C bioglass/calcite/carbon composites derived from novel silicone-based emulsions, leading to highly porous lattice scaffolds. These are produced by direct ink writing (DIW) 3D printing, followed by ceramic conversion at 700 degrees C in flowing nitrogen. The emulsions consisted of droplets of concentrated calcium nitrate aqueous solution incorporated into blends of H44 commercial polysiloxane and photocurable acrylate resin. This formulation offered unprecedented opportunities in both synthesis and shaping. Specifically, the homogeneous dispersion of the CaO precursor in silicone enabled a uniform SiO2/CaO distribution, favoring the formation of a glass matrix. Additionally, the acrylate component and water content allowed for tuning of the microstructure both immediately after printing and upon firing. Photopolymerization of acrylates consolidated the printed bodies (configuring a 'hybrid DIW') after extrusion, while water evaporation enhanced gas evolution during ceramic conversion, promoting pore interconnectivity.