Synthesis of Magnesium- and Silicon-modified Hydroxyapatites by Microwave-Assisted Method

Abstract

Nanopowders of hydroxyapatite (HA), modified by magnesium (MgHA) and by silicon (SiHA) were obtained by liquid-phase microwave synthesis method. X-ray diffraction and IR spectroscopy results showed that Mg2+ and SiO44− ions were present in the synthesized products both as secondary phases and as part of the HA phase. Whitlockite was found in the magnesium-modified HA (MgHA) and larnite was found in the silicon-modified HA (SiHA); ion substitution for both materials resulted in solid solutions. In the synthesized samples of modified HA, the increase of particle size of powders was in the order HA < SiHA < MgHA, which was calculated through data specific surface area and measured pycnometric density of the powders. The Lewis acid sites (Ca2+, Mg2+, Si4+) were present using spectral probes on the surface of the samples of HA, MgHA, and SiHA, and the acidity of these sites decreased in the order SiHA > MgHA > HA. The rates of calcium phosphate layer deposition on the surface of these materials at 37 °C in the model simulated body fluid solution showed similar dependence.

Mechanical and Biological Properties of Magnesium- and Silicon-Substituted Hydroxyapatite Scaffolds

“…in Figure 10, all scaffolds determined a significant increase in ALP activity after 14 and days in BMSC incubated in basal medium with respect to control cells, whereas afte days, no significant change was detected. However, ALP activity reached maximum v ues after 14 days of BMSC seeding on the scaffolds, while after 21 days, ALP valu showed a decrease while remaining higher than in control cells.…”

“…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 Mg 2+ and SiO 4 4− ions into the structure of HA, and it also accelerates the formation of a new apatite layer on the surface of the material [12][13][14]. Magnesium also plays an important role in mediating cell-extracellular matrix interaction, thus the incorporation of Mg 2+ in the HA crystal structure can facilitate new and dense bone formation as a result of the stimulated growth of osteoblasts [15,16].…”

Enhancing Bioactivity of Hydroxyapatite Scaffolds Using Fibrous Type I Collagen

“…(Bose et al, 2013 , Hoppe et al, 2011 ). Starting from this evidence, more scientific works reported the fabrication of ions doped apatite (Aina et al, 2012 ; Padmanabhan et al, 2014 ; Scalera et al, 2017 ; Rasskazova et al, 2019 ; Scalera et al, 2020 ). Among ions found in the natural bone tissues, magnesium and silicon play an important role in the development of new bone tissue, allowing the control of bioresorption and facilitating the biomineralization and the formation of bone stock on the surface of the material (Landi et al, 2008 ; Munir et al, 2011 ).…”

Physicochemical and Biological Properties of Mg-Doped Calcium Silicate Endodontic Cement

“…As the amount of Mg ion increases, the C3S peaks shift to a higher diffraction angle. These peak shift towards higher 2θ indicates a reducing d-spacing because the ionic radius of Mg 2+ (0.74 Å) is smaller than Ca 2+ (1.04 Å) [47]. Also, in Mg-CSC (Mg = 1 to 5%) specimens, the C2S peaks were formed, and these peaks present no shift with different contents of Mg ion.…”