Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Inorganic Chemistry

Hydroxyapatite (HA) is a biocompatible material with high binding activity to DNA and protein. Also, its lattice is eligible for substition in both Ca and P sites. Thus, Ca can be substituted by Sr, Na, and Fe while P is easily substituted by CO₃, Si and Se. Incorporation of selenium which is known to play a specific role in human health, may endow the materials with novel characteristics. Therefore, it was selected for the present study. A series of substituted nano-hydroxyapatite with 1-5% Se, (SeHA) powders were synthesised by an aqueous precipitation method using sodium selenite. The produced precipitates were dried at 60{u00B0}C. The dried ground powders were characterised by XRF, XRD, FTIR and TEM. The XRD patterns obtained confirm the substitution of Se ions in the crystal lattice of HA and was accompanied by the presence of Na ion as was detected by XRF; (SeHA1, SeHA1.5, SeHA2, SeHA2.5, SeHA3 and SeHA5). No change in the morphology of the rod shaped particles took place. Instead a reduction in their size was observed with increase in the selenium content. The cytotoxicity of the produced powders was evaluated in vitro on human bone marrow mesynchymal stem cells (BM-MSCs) and umbilical cord derived mesenchymal stem cells (UC-MSCs). The 0.59 mM of Se corresponding to 2% substitution in the lattice of HA (SeHA2) does not show cytotoxicity and stimulated the proliferation of UC-MSCs in contrast to pure HA powders which inhibited proliferation of the same cells

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