Protein adsorption and in vitro behavior of additively manufactured 3D-silicon nitride scaffolds intended for bone tissue engineering.

Highly porous scaffolds of Si ₃ N ₄ are fabricated by direct ink writing method (Robocasting) with a pattern of macroporous cavities of 650-700μm. Two different Si ₃ N ₄ ink compositions regarding the oxide sintering aids (namely, Y ₂ O ₃ , Al ₂ O ₃ , and SiO ₂ ) are tried. Both inks reach solid volume fractions of ~0.40 with about 10-12wt% of polymeric additive content that imparts the necessary pseudoplastic characteristics. The printed structures are sintered under controlled N ₂ atmosphere either in a conventional graphite furnace or by the spark plasma sintering technique. Skeleton of the scaffolds reaches densities above 95% of the theoretical value with ≈18-24% of linear shrinkage. Analysis of the crystalline phases, microstructure and mechanical properties are comparatively done for both compositions. The bioactivity of these structures is addressed by evaluating the ion release rate in simulated body fluid. In parallel, atomic force microscopy is used to determine the effect of the filaments surface roughness on protein adsorption (Bovine Serum Albumin) for assessing the potential application of 3D-Si ₃ N ₄ scaffolds in bone regeneration.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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