Abstract
Magnesium (Mg)- and silicon (Si)-substituted hydroxyapatite (HA) scaffolds were synthesized using the sponge replica method. The influence of Mg2+ and SiO44− ion substitution on the microstructural, mechanical and biological properties of HA scaffolds was evaluated. All synthesized scaffolds exhibited porosity >92%, with interconnected pores and pore sizes ranging between 200 and 800 μm. X-ray diffraction analysis showed that β-TCP was formed in the case of Mg substitution. X-ray fluorescence mapping showed a homogeneous distribution of Mg and Si ions in the respective scaffolds. Compared to the pure HA scaffold, a reduced grain size was observed in the Mg- and Si-substituted scaffolds, which greatly influenced the mechanical properties of the scaffolds. Mechanical tests revealed better performance in HA-Mg (0.44 ± 0.05 MPa), HA-Si (0.64 ± 0.02 MPa) and HA-MgSi (0.53 ± 0.01 MPa) samples compared to pure HA (0.2 ± 0.01 MPa). During biodegradability tests in Tris-HCl, slight weight loss and a substantial reduction in mechanical performances of the scaffolds were observed. Cell proliferation determined by the MTT assay using hBMSC showed that all scaffolds were biocompatible, and the HA-MgSi scaffold seemed the most effective for cell adhesion and proliferation. Furthermore, ALP activity and osteogenic marker expression analysis revealed the ability of HA-Si and HA-MgSi scaffolds to promote osteoblast differentiation.
Highlights
Element mapping and spectra of HA-MgSi scaffolds are shown in Figure 3b,c, respecXRF measurements reveal that Mg and Si ions are homogeneously distributed in the tively
Mg- and Si-substituted HA scaffolds were fabricated from hydroxide coprecipitation combined with the sponge replica method
X-ray fluorescence fluorescence (XRF) analysis confirmed the homogeneous distribution of Mg and Si ions on each scaffold
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. An ideal bioactive material should be nontoxic and form bonds with surrounding bone tissue after implantation. Ideal scaffolds for bone tissue regeneration require an interconnected and highly porous (>90%) 3D structure to allow cell migration, vascularization and nutrient diffusion [6]. Kim et al reported enhanced biocompatibility of magnesium- and silicon-substituted sintered HA and suggested that it could be a useful material for bone augmentation [11]. The processes of bioresorption can be controlled by the substitution of Mg2+ and SiO4 4− ions into the structure of HA, and it accelerates the formation of a new apatite layer on the surface of the material [12,13,14]. Despite the wide interest towards using Mg2+ and SiO4 4− in the field, the synergistic role of these ions towards the bioactivity of porous scaffolds (HA-MgSi) has not been investigated yet. To the best of our knowledge, there are no reports on sintered HA-MgSi composite scaffolds evaluated for physical, mechanical, biodegradation and biocompatible properties
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