The improved textural properties, thermal stability, and cytocompatibility of mesoporous hydroxyapatite by Mg2+ doping

Abstract

The paper demonstrated the increase of the surface area and meso- and microporosity volume with the low concentration Mg-substitution introduction during the hydroxyapatite (HA) wet method synthesis, as well as samples phase and structure evolution during the heat treatment up to 1200 °C. The incorporation of 0.1 and 1.0 mol.% Mg2+ were studied by magnetic resonance techniques including electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), magic angle spinning nuclear magnetic resonance (MAS NMR) depending on Mg2+ content, and thermal treatment temperature. The calculation based on Density Functional Theory (DFT) was conducted and a model of the Mg2+ introduction was proposed, which correlated with the unit cell volume evaluations. Incorporation of 0.1 mol. % Mg2+ resulted in the growth of specific surface area (S) on the 37%, while 1.0 mol. % Mg-HA powders demonstrated a more than three times increase of surface area up to 86.91 m2/g compared to 23.35 m2/g for pure HA. The micro- and mesopores volume also demonstrated the near three time growing up with a total pore volume of 0.2938 mm3/g. The established properties indicated the opportunity to apply these materials for water, air, and soil purification, catalyst, as well as active phase support and bone tissue repair including drugs and proteins delivery systems. The in vitro investigations demonstrated the cytocompatibility of the bioceramic granules and confirmed the positive influence of the Mg2+ on cell viability and proliferation.