ABSTRACT
Silicon is an effective element in bone biomineralization; hence Si-substituted hydroxyapatite can be a relevant bioceramic as bone materials substitution. Stoichiometric hydroxyapatite [HA] and Si-substituted hydroxyapatite [Si-HA] with different contents of Si substitution were synthesized successfully by a hydrothermal method using Ca [NO3] 2, [NH4] 3PO4 or [NH4] 2HPO4 and Si [OCH2CH3] 4 [TEOS] as starting materials. Crystalline Phases, chemical composition, microstructure and morphology of synthesized powders were investigated using X-ray diffraction [XRD], Fourier transform IR spectroscopy [FTIR], inductively coupled plasma AES [ICP-AES] and scanning electron microscopy [SEM] techniques. The results proved silicon substitution in hydroxyapatite structure and revealed that the substitution of phosphate groups by silicate groups caused some OH-loss to maintain charge balance and the lattice parameters slightly changed with respect to stoichiometric HA. Si-incorporation reduces the crystallites size of Si-HA and crystallinity, thus the solubility of Si-HA powders increases, and as a result Si-substitution has improved bioactivity behavior of HA. Based on in-vitro tests; soaking and incubating the specimens in simulated body fluid [SBF] and MTT assays [Dimethylthiazol assay], Si-substituted hydroxyapatite is more bioactive than pure hydroxyapatite