Preparation, Micro-analysis And Biological Activity Of Nano-hydroxyapatite Coating

Hydroxyapatite is short for HA. It is not only of the ideal biological activity, biocompatibility and bone conductivity, but also of very rich surface properties and strong ability of adsorbing and exchanging substances. Its powder has been widely used for tissue engineering, drug carriers, sensors, catalysts, optoelectronic materials, chemical engineering and environmental engineering and other fields. In these fields, it is one of the hotspots that the hydroxyapatite coating is applied to modifiy and improve the biological properties of the inert and medical metal such as titanium, stainless steel and titanium alloy. In this paper, nano-hydroxyapatite coating and its composite coating were prepared on the medical titanium substrate by sol-gel method. Through surface micro-analysis technology, the effects of different preparation conditions and substrate activation on the composition, microstructure, morphology and properties of the coating were explored. On the other hand, the biodegradation, deposition and safety of the coating were investigated via simulated body fluid immersion test and cell cytotoxicity test. The paper consists of the following five parts:Chapter 1: Introduction.The structure and physical and chemical properties of hydroxyapatite are introduced. Under the above premise, some problems and difficulties in this field are also summerized. Simultaneously, its development and application prospects are discussed.Chapter 2: Preparation of nano-hydroxyapatite by sol-gel method and its micro analysis. Nano-hydroxyapatite powder was prepared by sol-gel method in this chapter. The effects of pH value, water-bath temperature, aging time and annealing temperature on the phase and microstructure of hydroxyapatite was explored systematically. And the formation mechanism of n-HA was also preliminaryly discussed. All these laid the foundation for the preparation of n-HA coating.Chapter 3: Preparation and micro-analysis of nano-hydroxyapatite coating on the titanium substrate. In this chapter, the nano-hydroxyapatite coating was prepared on the titanium substrate by spin-coating method. The effects of different pretreatment method for titanium substrates and drying methods on the microstructure of the coating was investigated respectively. Finally, the suitable process conditions for preparing uniform and compact n-HA coating with fewer cracks were determined.Chapter 4: Preparation and micro-analysis of n-HA/SiO₂ composite coating. The n-SiO₂ powder was prepared in this part. Mix HA sol and SiO₂ sol directly through wet mechanical agitation method. And drop the blend sol on the titanium substrate to prepared n-HA/SiO₂ composite coating. The phase and microstructure of n-SiO₂ and n-HA/SiO₂ coating were studied, and the effect of adding SiO₂ on the n-HA coating was also discussed.Chapter 5: Biological activity and toxicity evaluation of n-HA coating and n-HA/SiO₂ composite coating. The simulated body fluid immersion experiment and MTT test were carried out for the n-HA coating and n-HA/SiO₂ coating materials. The biological activity and safety of the coating were evaluated from the view of microstructure change and cell survival rate respectively.