Study On Synthesis Methods Of Nano-hydroxyapatite And Its Composites

Hydroxyapatite is the main inorganic material in human teeth and bone tissue.Nano-hydroxyapatite and its composites have been widely used in bone-like materials due to their excellent biocompatibility and bioactivity.Microwave heating is a kind of heating method that can quickly and completely heat materials.It can not only accelerate the reaction rate,but also change the disadvantage of uneven particle size caused by uneven heating.In this thesis,we first studied the synthesis method,and explored a new method of nano-hydroxyapatite synthesized by microwave assisted sol-gel method.Then,nano-hydroxyapatite was modified by arginine and poly-arginine to increase its biocompatibility.The modified hydroxyapatite and nano clay were combined to prepare composite materials,which had great potential in regenerative tissue engineering and medical applications.(1)In this thesis,nHAP was successfully prepared by microwave-assisted sol-gel method.The effects of different experimental conditions on the crystallinity,purity and particle size of the products were investigated from three aspects of reaction solvents(water and ethanol),synthesis temperatures(25,40 and 60?)and microwave(on and off).The products were characterized by TGA,TEM,FTIR,XRD and SEM.It was found that ethanol was a better solvent for the sol-gel method in producing nHAP with high crystallinity and good purity,and the size of the nHAP particle increased along with the raise of temperature.We developed a new method for preparing nHAP:microwave-assisted sol-gel method,which greatly improves the reaction efficiency compared with the traditional method,and has great potential in the synthesis of nano particles.(2)In this thesis,Arg and poly-Arg were successfully modified on the surface of nHAP by coprecipitation methods.The content of Arg in nHAP-Arg was determined by Ninhydrin chromogenic method.The Arg and poly-Arg were successfully modified on nHAP,which demonstrated by XRD and FTIR,and the morphologies of nHAP-Arg and nHAP-poly-Arg crystals were observed by TEM.The results showed that the distribution of modified nHAP particles were more uniform.Then we investigated the interaction between NCs and nHAP modified by Arg or poly-Arg.NCs/nHAP-Arg and NCs/nHAP-Arg composites were prepared and their mechanical properties were investigated.It was found that the interfacial interaction force between modified nHAP and NCs became stronger.The crystal characteristics and morphologies were characterized by a series of characterization methods.The mechanism of the interfacial interaction of NCs enhanced by Arg crosslinking agent was elucidated by ITC and rheological experiments.The results showed thaat the formation of molecular interactions between NCs and nHAP-Arg/nHAP-poly-Arg was achieved by enhancing gelation behavior of NCs with Arg.The above studies showed that nHAP is successfully prepared by microwave assisted sol-gel process,which greatly shorten the reaction time.Arginine and polyarginine enhanced the interfacial interaction between hydroxyapatite and nano-clay,and successfully prepared a new type of composite material with good mechanical properties,which broadened the potential application of hydroxyapatite in bone tissue engineering and regenerative medicine.