engleski

PREPARATION OF HIGHLY POROUS MAGNESIUM-DOPED HYDROXYAPATITE FROM CUTTLEBONE AS BIOACTIVE MATERIAL

One of the main objectives in bone tissue engineering is synthesis of biomaterials that resemble natural bone in structure and composition. Bone mineral has a similar chemical composition to synthetic hydroxyapatite (HAp, Ca10(PO4)6(OH)2) but contains several ionic substitutions. Magnesium, Mg, is one of the predominant substitutes for calcium in biological apatite and plays an important role in bone growth. Objectives: The objective of this work was to investigate the influence of Mg2+ concentration on chemical composition, morphology, porosity, crystallographic structure and biocompatibility of porous HAp scaffold derived from cuttlebone. Methods: Hydroxyapatite and Mg substituted hydroxyapatites (Mg-HAp) were hydrothermally synthesised. Mg-HAp samples were prepared by addition of Mg2+ (MgCl2×6H2O or Mg(ClO4)2) with respect to (Ca+Mg)/P=10/6 molar ratio. The compositional and morphological properties of the scaffolds were studied by means of X-ray diffraction with Rietveld refinement, FTIR spectroscopy, thermogravimetric analysis and scanning electron microscopy with elemental mapping analysis. Cytotoxicity was determined using MTT assay on human embryonic kidney cell line, while osteogenic potential was evaluated by human mesenchymal stem cell culture. Results: The highly porous interconnected structure is completely preserved after the hydrothermal conversion of cuttlebone. HAp structure is substituted with HPO42- and B-type carbonate. With the increase of magnesium concentration, more whitlockite phase (Ca10-xMgx(HPO4)(PO4)6) was formed. The homogeneous distribution of ions and non-cytotoxicity was confirmed. Histological and immunohistochemical analyses, and evaluation of osteogenic genes expression indicated better osteogenic properties of Mg doped scaffolds with respect to the pure HAp. Discussion: The incorporation of Mg in the HAp lattice structure is limited unless other ions are incorporated simultaneously. Whitlockite can easily incorporate magnesium into structure ensuring better bioresorption under physiological conditions then HAp. Controlling the Mg substitution, the bioactivity and biocompatibility of 3D porous scaffolds based on substituted hydroxyapatite can be improved.

hydroxyapatite ; cuttlebone ; magnesium-doped ; bioactive material

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