Ca:Mg:Zn:CO ₃ and Ca:Mg:CO ₃ —tri- and bi-elemental carbonate microparticles for novel injectable self-gelling hydrogel–microparticle composites for tissue regeneration

Abstract

Injectable composites for tissue regeneration can be developed by dispersion of inorganic microparticles and cells in a hydrogel phase. In this study, multifunctional carbonate microparticles containing different amounts of calcium, magnesium and zinc were mixed with solutions of gellan gum (GG), an anionic polysaccharide, to form injectable hydrogel-microparticle composites, containing Zn, Ca and Mg. Zn and Ca were incorporated into microparticle preparations to a greater extent than Mg. Microparticle groups were heterogeneous and contained microparticles of differing shape and elemental composition. Zn-rich microparticles were 'star shaped' and appeared to consist of small crystallites, while Zn-poor, Ca- and Mg-rich microparticles were irregular in shape and appeared to contain lager crystallites. Zn-free microparticle groups exhibited the best cytocompatibility and, unexpectedly, Zn-free composites showed the highest antibacterial activity towards methicilin-resistant Staphylococcus aureus. Composites containing Zn-free microparticles were cytocompatible and therefore appear most suitable for applications as an injectable biomaterial. This study proves the principle of creating bi- and tri-elemental microparticles to induce the gelation of GG to create injectable hydrogel-microparticle composites.

Porous Alginate Scaffolds Assembled Using Vaterite CaCO3 Crystals

“…Therefore, there was no need to eliminate CaCO 3 crystals in order to form the pores, and even vice versa, the crystals have been kept in the final scaffold architecture. A straightforward approach for the fabrication of composite CaCO 3 -alginate gel materials was first employed nearly one decade ago and has been based on the simultaneous growth of CaCO 3 crystals and gelation of alginate hydrogel [138,139,140,141,142]. In this design, calcium carbonate crystals grow in the presence of the gel and get entrapped inside this polymer matrix.…”

Marine-Inspired Enzymatic Mineralization of Dairy-Derived Whey Protein Isolate (WPI) Hydrogels for Bone Tissue Regeneration

“…It was found that increased magnesium concentration reduced the crystallinity of CaCO 3 . This observation was confirmed by two other bands typical for calcite (at 281 and 154 cm −1 ), which were also broader in WPI_U_MC than in WPI_U_MA and WPI_U_MB [17,23,24]. The decrease in intensity and band sharpness in the order WPIU_MA > WPIU_MB > WPIU_MC suggests a decrease in crystallinity in the same order.…”

“…Mar. Drugs 2020, 18, x 6 of 14 also broader in WPI_U_MC than in WPI_U_MA and WPI_U_MB [17,23,24]. The decrease in intensity and band sharpness in the order WPIU_MA > WPIU_MB > WPIU_MC suggests a decrease in crystallinity in the same order.…”

Inter-protein interactions govern protein loading into porous vaterite CaCO3 crystals

“…27,28 In addition, CaCO 3 crystals can be used as sacrificial templates for the formulation of porous protein 29 and polymer beads, 30,31 and layer-by-layer assemblies to produce multilayer capsules. [32][33][34][35] All these findings indicate that CaCO 3 crystals are promising carriers for the encapsulation of protein-based therapeutics for oral, [36][37][38] intravenous, 17 intratumoral, 39 intranasal, 40 and mucosal drug delivery; 41,42 tissue engineering 43,44 and regeneration; 45,46 and diagnostics. 47,48 This diversity of administration routes enabled by CaCO 3 for protein delivery is especially important because in current medical practice, protein drugs are predominantly available in injectable formulations, but the demand for non-invasive drug delivery systems for therapeutic proteins is high.…”