Preparation,Microstructure Control And Performance Study Of Chitosan/Nano-hydroxyapatite Composite Microspheres

Chitosan is abbreviated as CS.It is not only a natural biodegradable polysaccharide with a positive charge,but also is provided with non-toxic,antibacterial,antioxidant,enhanced gelling,hydroxyl absorption,antitumor,no mutagenic effect and other characteristics.So chitosan has been widely used in the fields of biomedicine,foodstuff,chemical,sewage treatment and many others realms.In these areas,it is one of the most hot spots at home and abroad that a new type composite materials was prepared by using chitosan with special physical,chemical and biological properties and other inorganic materials.In this study,CS microspheres and CS/nHA composite microspheres were prepared by crosslinking-emulsion.The effect of different preparation conditions on the microstructure of the product was systematically investigated,and the microstructure regulation of the microspheres was realized.On this premise,the adsorption properties,the drug loading and sustained release properties of the two microspheres were compared and analyzed.The full text is divided into the following five parts:In chapter one: Introduction.The structure and properties of chitosan and hydroxyapatite are introduced.Under this premise,the preparation methods of chitosan microspheres were introduced,and what's more,the research status,existing problems and application progress of chitosan and its composite microspheres were discussed.In chapter two: Preparation and microstructure control of chitosan microspheres.Chitosan microspheres were prepared by crosslinking-emulsion,which had good regularity,uniformity and good dispersibility.The effects of stirring speed,pH value,water bath temperature,amount of crosslinking agent,volume ratio of oil to water on the microstructure and morphology of CS microspheres were investigated.In chapter three: Preparation and microstructure analysis of chitosan/hydroxyapatite composite microspheres.On the basis of the preparation of nano-hydroxyapatite,CS/nHA composite microspheres were prepared by inverse crosslinking-emulsion,which had larger specific surface area,better homogeneity and dispersibility.In chapter four: Study on adsorption properties of chitosan and its composite microspheres.The adsorption properties of chitosan microspheres and CS/nHA composite microspheres were studied by using phenol simulated wastewater as adsorbent.The adsorption mechanism was analyzed by adsorption kinetics theory and thermodynamics theory.The relationship between microstructure and properties of microspheres was also discussed.In chapter five: Drug loading and release properties of chitosan and its composite microspheres.The drug loading properties of CS microspheres and CS/nHA composite microspheres were investigated by using norfloxacin as the drug loading model.On this basis,the sustained release of drug microspheres under different media of water and saline was studied.The results show that CS/nHA composite microspheres have better stability and drug release properties than CS microspheres.and can be applied to biomedical field.Therefore,CS microspheres and CS/nHA composite microspheres can be applied to the field of biomedicine.