Strontium-containing Hydroxyapatite Research Articles

A novel injectable bioactive bone cement for spinal surgery: a developmental and preclinical study.

The injection of bone cement by minimally invasive techniques for the treatment of vertebral body fractures or for stabilization of an osteoporotic vertebral body is regarded as promising in spinal surgery. The purpose of this study was to develop a novel injectable bioactive bone cement to address such concerns. The cement was composed mainly of strontium-containing hydroxyapatite (Sr-HA) filler and Bisphenol A Diglycidylether Dimethacrylate (D-GMA) resin. The Sr-HA filler was prepared by precipitation and calcination, then analyzed with Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns. Samples of strontium-containing hydroxyapatite cement (SrHAC) were formed by a combination of powder filler and resin matrix, with the setting time and peak temperature recorded. Cell relative growth rate (RGR), Tetrazolium bromide (MTT), and haemolysis tests were used to detect initial in vitro biocompatibility of the new cement. In vitro spinal biomechanical testing and morphological observation after bone cement injection were performed on pig spines. Results indicate that the setting time and peak temperature of the cement was 15 min and 55 degrees C, respectively. Cytotoxicity of the cement was class 1 (no cytotoxicity) and haemolysis was 1% (no haemolysis). Stiffness after cement injection and fatigue loading were 112% and 95% of the intact bone, respectively, which is similar to that of natural bone. Radiopacity of SrHAC allowed easy radiographic imaging. The use of SrHAC cement is, thus, promising in spinal surgery.

Synergistic effects in the oxidation of methane on strontium and lead hydroxyapatites

The oxidation of methane has been investigated on lead hydroxyapatite (PbHAp), strontium hydroxyapatite (SrHAp) and their binary mixtures at 873 K. PbHAp showed no activity for the oxidation of methane, while SrHAp produced carbon monoxide selectively at 2–4% conversion. On binary mixtures of the hydroxyapatites the conversion of methane and the selectivity to C2 compounds reached values higher than those of the separate constituents of the mixture. With tetrachloromethane in the feed stream a similar synergistic effect was observed with conversions of methane and selectivities to CH3Cl higher on the binary mixtures than those on either SrHAp or PbHAp. The strontium-containing hydroxyapatite appears to play a crucial role in the activation of methane, while the presence of the lead-containing analogue is apparently required for the minimization of undesirable processes involving methyl radicals.