Polymer-Derived Biosilicate®-like Glass-Ceramics: Engineering of Formulations and Additive Manufacturing of Three-Dimensional Scaffolds.

Fulden Dogrul,Dušan Galusek,Martin Michálek,Liliana Liverani,Aldo R Boccaccini,Hamada Elsayed,Enrico Bernardo,Paulina Ożóg

doi:10.3390/ma14185170

Abstract

Silicone resins, filled with phosphates and other oxide fillers, yield upon firing in air at 1100 °C, a product resembling Biosilicate® glass-ceramics, one of the most promising systems for tissue engineering applications. The process requires no preliminary synthesis of parent glass, and the polymer route enables the application of direct ink writing (DIW) of silicone-based mixtures, for the manufacturing of reticulated scaffolds at room temperature. The thermal treatment is later applied for the conversion into ceramic scaffolds. The present paper further elucidates the flexibility of the approach. Changes in the reference silicone and firing atmosphere (from air to nitrogen) were studied to obtain functional composite biomaterials featuring a carbon phase embedded in a Biosilicate®-like matrix. The microstructure was further modified either through a controlled gas release at a low temperature, or by the revision of the adopted additive manufacturing technology (from DIW to digital light processing).

Highlights

The amounts of other fillers were calibrated according to the oxide balance of Biosilicate® glass-ceramics (Figure 2a) and to the ‘oxide yield’ of the chosen compound
Given the CaO/SiO2 proportion in Biosilicate®, any 10 g of SiO2 had to be accompanied by 4.9 g of CaO, in turn provided by 8.74 g of calcite (CaCO3, undergoing decomposition upon heating)
Silicone resins resins combined manufacturing of Silicone combined with withoxide oxidefillers fillerswere wereused usedfor forthe theadditive additive manufacturing reticulated scaffolds, which, after firing, resembled

Summary

Introduction

Preceramic polymers [1], especially in the form of polysiloxanes, known as ‘silicones’, have been recently recognized as raw materials for a new generation of bioceramics, such as Ca-, Ca-/Mg- and Ca-/Zn- silicates [2,3,4,5,6,7]. Silicone resins, embedding micro- and nano-sized fillers, consisting of carbonates, hydroxides or simple oxides may yield the desired silicate with excellent purity, at a generally lower temperature (900–1100 ◦ C), offering interesting shaping possibilities [8,9,10,11,12,13]. The use of silicones as a silica source (after firing) may be considered as safe, considering the direct application of these polymers in composites for tissue engineering [9]

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