Controable Preparation Of Nano-sized Hydroxyapatite In Rotating Pached Bed Reactor And Its Performance Study

Hydroxyapatite(HAp)is a very important biomedical material.HAp is main inorganic component of nature bone,and has good bioactivity and biocompatibility.In addition,HAp has also a good adsorption ability and can be used as carriers of drugs,proteins and genes,etc.In order to improve the application value of HAp,the preparation of HAp nanoparticles with different morphologies and good dispersibility has become a hot research topic in the field of biomaterials.Thus,in this master thesis,our objective is to synthesis nano-sized HAp and its dispersion with different aspect-ratios based on high-gravity technology combined with hydrothermal method.Moreover,the related biomedical performaces were investigated.The main research contents were as follows.1.Nano-sized HAp with various aspect raitos was prepared based on high gravity technology combined with hydrothermal method by introducing CO(NH2)2 and NH3·H2O as aspect ratio modifier.The effects of hydrothermal temperature,reactant concentration,the molar ratio of CO(NH2)2 and NH3 H20,and the rotating speed of RPB on the morphology and particles size of nano-sized HAp were explored.The optimal prepareation conditions were obtained as followed:hydrothermal temperature of 200?,reactant concentration of 0.2 mol/L,rotating speed of 2500 rpm and molar ratio of CO(NH2)2 and NH3·H2O from 0:4 to 4:0.As compared to those synthesized by a conventional stirred tank reactor(STR),the RPB reactor had HAp nanorods with a smaller particle width and a wider range of aspect ratio(RPB:2.2-39;STR:3.4-22),and a much shorter reaction time from 20 min to 1 s..2.Nano-HAp dispersion in water phase and organic phase was prepared based on high gravity technology combined with hydrothermal method by using sodium citrate(Na3Cit),OP and CTAB as surfactants.The effects of hydrothermal temperature,reactant concentration,surfactant addition and the rotating speed of RPB on the particle size and the dispersibility of nano-sized HAp were investigated.The as-prepared nano-HAp dispersion appeared good transparency and dispersion stability,which had a uniform particle distribution,an average aprticle size of 30-300 nm and a controlled aspect ratio of 3-13.3.The biological performaces of the as-prepared nano-HAp were investigated.HAp/pectin composite bone cements were prepared by combining different aspect ratios of nano-HAp and pectin solution.The water resistance,morphology and compressive strength of the samples were studied.Moreover,cell compatibility of nano-HAp was also evaluated.The resulsts indicated that the HAp/pectin composite cement had a good water resistance,and little effect on the pH of PBS.The compressive strength of HAp/pectin composite cement firstly increased and then decreased with the increasing of aspect ratio of nano-HAp.At an average aspect ratio of 15,there was the highest compressive strength of 29.4 MPa.Moreover,HAp namodisersion prepared by Na3Cit and OP had good biocompatibility and low cytotoxicity.