Synthesis of different sized and porous hydroxyapatite nanorods without organic modifiers and their 5-fluorouracil release performance.

Porous biocompatible hydroxyapatite (HAP) nanorods of various sizes were synthesized by the combination of chemical precipitation and hydrothermal method without the use of organic modifiers. The HAP nanorod samples were characterized by powder X-ray diffraction, transmission electron microscopy, and N2 adsorption/desorption techniques. HAP nanorods with average diameters and average lengths ranging from 8.5 to 26.6 nm and from 23.1 to 49.7 nm, respectively, could be controllably synthesized via these methods. Low autoclaving temperature and high pH value favored the formation of relatively small HAP nanorods. The TEM images showed that the nanorods possessed porous structures with average pore diameters ranging from 1.6 to 2.7 nm. These HAP nanoparticles effectively prolonged the release time of 5-fluorouracil up to 24h. The as-synthesized HAP nanorods displayed no cytotoxicity to bone marrow stem cells at low HAP concentration, indicating that these nanorod materials could serve as potential carriers for novel drug release systems.

Size-controlled preparation of α-calcium sulphate hemihydrate starting from calcium sulphate dihydrate in the presence of modifiers and the dissolution rate in simulated body fluid.

Different-sized α-calcium sulphate hemihydrate (α-CSH) rods were hydrothermally prepared by converting calcium sulphate dihydrate at 110-140°C in the presence of MgCl2, sodium citrate (CANa), and sodium dodecyl benzene sulfonate (SDBS) as the modifiers. The α-CSH rods with the average diameters and the average lengths in the ranges of 2.6-5.2 and 17.5-33.1 µm, respectively, were tunably prepared. The presence of the modifiers favoured the formation of small-sized α-CSH rods. The effect of the modifiers on decreasing the diameters of α-CSH rods was in an order of SDBS>CANa>MgCl2. The dissolution rates of the different-sized α-CSH rods prepared at 140°C in simulated body fluid were in an order of α-CSH (CANa)>α-CSH (MgCl2)>α-CSH (reference)>α-CSH (SDBS). The naked and small-sized α-CSH rods had high dissolution rates. The adsorption of SDBS on the surfaces of α-CSH rods decreased their dissolution rates.