Synthesis, characterization and ab initio simulation of magnesium-substituted hydroxyapatite.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Nanotechnology

Background:

• Hydroxyapatite (HA) is a crucial biomaterial, but its properties can be tuned by doping.
• Magnesium (Mg) is a biologically relevant ion that can influence HA's structural and thermal characteristics.

Purpose of the Study:

• To investigate the effects of magnesium substitution on hydroxyapatite nano-crystals.
• To determine the optimal conditions and sites for Mg incorporation in HA.
• To understand the impact of Mg on HA's structural, thermal, and morphological properties.

Main Methods:

• Synthesis of Mg-substituted HA nano-crystals via wet-chemical precipitation at 90°C.
• Comprehensive characterization using X-ray diffraction (XRD), X-ray fluorescence (XRF), electron microscopy (SEM, HR-TEM), and thermogravimetric analysis (TGA).
• Rietveld refinement for structural analysis and ab initio density functional theory (DFT) for computational modeling.

Main Results:

• Successful substitution of calcium by a limited amount of magnesium (5-7 mol%) in HA.
• Mg substitution led to smaller, more irregular HA crystallites, increased agglomeration, reduced crystallinity, and decreased thermal stability.
• Lattice constants 'a' and 'c' decreased with increasing Mg content; DFT simulations indicated Ca(1) sites are energetically favored for Mg substitution.

Conclusions:

• Magnesium incorporation modifies the structural, thermal, and morphological properties of hydroxyapatite nano-crystals.
• The study provides insights into the preferential site of Mg substitution within the HA lattice.
• Findings are relevant for designing tailored HA-based biomaterials with enhanced properties.