Synthesis of silicon-substituted hydroxyapatite by a hydrothermal method with two different phosphorous sources

摘要

Silicon-substituted hydroxyapatite (Si-HA) with up to 1.8 wt% Si content was prepared successfully by a hydrothermal method, using Ca(NO_3)_2, (NH_4)_3PO_4 or (NH_4)_2HPO_4 and Si(OCH_2CH_3)_4 (TEOS) as starting materials. Silicon has been incorporated in hydroxyapatite (HA) lattice by partially replacing phosphate (PO_4~(3-)) groups with silicate (SiO_4~(4-)) groups resulting in Si-HA described as Ca_(10)(PO_4)_(6-x)(SiO_4)_x(OH)_(2-x). X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), inductively coupled plasma AES (ICP-AES) and scanning electron microscopy (SEM) techniques reveal that the substitution of phosphate groups by silicate groups causes some OH~ loss to maintain the charge balance and changes the lattice parameters of HA. The crystal shape of Si-HA has not altered compared to silicon-free reference hydroxyapatite but Si-incorporation reduces the size of Si-HA crystallites. Based on in vitro tests, soaking the specimens in simulated body fluid (SBF), and MTT assays by human osteoblast-like cells, Si-substituted hydroxyapatite is more bioactive than pure hydroxyapatite.