Highly Porous Sr/Mg‐Doped Hardystonite Bioceramics from Preceramic Polymers and Reactive Fillers: Direct Foaming and Direct Ink Writing

Abstract

Novel hardystonite-based bioceramics are obtained by thermal treatment, in air, of silicone resins and reactive fillers. Using commercial silicones embedding SrO and MgO precursors, in addition to CaO and ZnO precursors, a quite complex solid solution (Ca 1.4 Sr 0.6 Zn 0.85 Mg 0.15 Si 2 O 7 ) can be achieved, at 1100 C, instead of pure hardystonite (Ca 2 ZnSi 2 O 7 ), with improvements in biocompatibility and bioactivity. Highly porous foams are obtained by gas evolution at the early stage of heat treatment (at 300-350 C), from the dehydration of active filler present in hydrated form (Mg(OH) 2 ). Additionally, direct ink writing of silicone-based pastes is used for the manufacturing of scaffolds with non-stochastic pore architecture. In the latter case, strong scaffolds (with compressive strength exceeding %12 MPa) are obtained by adding fine glass powders as an additional filler. This addition enhances the viscous flow upon firing, but do not compromise the phase evolution, owing to the exact match in the composition between glass and silicone/filler mixture. Figure 4. 3D printed scaffolds: a) after drying (spacing ¼ 1.6 mm); b) after ceramization; c), d) top view of the scaffolds after firing; e), f) cross-sections of ceramized scaffolds.

Biological evaluation of preceramic organosilicon polymers for various healthcare and biomedical engineering applications: A review

“…An interesting approach to generating an analogue of pure hardystonite (Ca 2 ZnSi 2 O 7 ) materials involves the use of preceramic polymers such as polysiloxane and inorganic fillers such as SrCO 3 , and Mg(OH) 2 to produce Sr/Mg doped hardystonite foam materials (Ca 1.4 Sr 0.6 Zn 0.85 Mg 0.15 Si 2 O 7 ) that may be useful as scaffolds for bone tissue engineering 83 . Hybrid treatments combining direct foaming and direct ink writing of silicone‐based pastes have been applied to produce highly porous cellular Sr/Mg doped hardystonite materials after firing at 1,100°C for 1 hr.…”

“…MTT assay of fibroblast cells cultured on control condition (tcp), pure hardystonite and Sr/Mg‐doped hardystonite ceramics. The column charts are related to the cell proliferation rate as a function of seeding time at 1, 3, 7, and 14 days 83 . Reproduced with permission from John Wiley & Sons…”

Bioactive Glass and Silicate-Based Ceramic Coatings on Metallic Implants: Open Challenge or Outdated Topic?

“…Nevertheless, cell differentiation was superior on strontium-substituted hardystonite coatings compared to all the other groups. As both silica-based coatings had similar surface topography, it was suggested that the release of Sr ions—rather than surface topography—was responsible of the higher differentiation on strontium-substituted hardystonite compared to hardystonite ones [140,187,188].…”

Carbon‐Bonded Alumina Spaghetti Filters by Alginate‐Based Robo Gel Casting

“…To ensure the retention of the component shape after printing, the ink instantly has to be dried, [49] gelled, [50,51] or exposed to a significant viscosity increase [52] based on shear-thinning behavior. In the last decades, progress was made especially in the fields of bioceramics and [53][54][55] functional ceramics, [49,52] among others. Based on this technique, the manufacturing of complex geometries at very high resolution can be achieved.…”