Preparation Of Magnetic Hydroxyapatite/Chitosan Nanomaterials And Study Of Their Properties On Protein Adsorption

Due to the diversity and complexity of current diseases,the demand for modern medicines is getting higher.Drug sustained-release system can effectively solve the problems of low drug delivery efficiency and short effect time,and also has better effect on the treatment of some chronic diseases.Therefore,the study of drug-loaded protein drug sustained-release carriers with non-toxic and large drug loading have become a important field for many researchers.Hydroxyapatite?HAp?,as the main inorganic component of human hard tissue,is non-toxic and non-irritating,which can participate in metabolism in vivo with good biocompatibility and biological activity.However,due to poor biomechanical properties and high brittleness,it is limited in practical application.In view of the problems existing in hydroxyapatite,the development of composite materials has become an effective way to solve the shortage of single materials.Chitosan?CS?is an effective carrier for drug-controlled release which possesses favourable biodegradability,biocompatibility and non-antigenicity.In recent years,the composite material composed of CS mixed in HAp has attracted extensive attention.It is also one of the research difficulties in this field to prepare targeted drug delivery systems with controllable drug delivery,non-toxicity and good biocompatibility.In this graduation thesis,HAp/CS nano powders were firstly successfully prepared by hydrothermal method,the magnetic hydroxyapatite/chitosan?MCHAp?composites were prepared on this basis.The products were characterized by X-ray diffraction?XRD??Fourier transform infrared spectrum?FTIR??scanning electron microscopy?SEM??vibrating sample magnetometer?VSM?and analysis of specific surface area and pore structure.Bovine serum protein?BSA?and lysozyme?LYS?were used as model protein drugs to carry out in vitro loading and releasing experiments,and explore the changes of bacteriostatic activity before and after adsorption of lysozyme.The main results are summarized as follows:?1?Firstly,HAp/CS and MCHAp composites were successfully prepared.HAp/CS was fitted as hexagonal orthorhombic system structure.With the increase of hydrothermal temperature,the crystallinity of the sample becomes higher,and the morphology gradually ranges from fluffy porous to blocky,and the specific surface gradually decreases.MCHAp is a kind of amorphous nano-powder.The specific surface of the composite increases obviously,and the crystal plane spacing enlarges with the addition of dispersant.The MCHAp under different conditions all possess superparamagnetism,and the magnetic induction strength increases with the increase of Fe₃O₄ addition.?2?Then the effects of different factors of HAp/CS on the adsorption and release of BSA and LYS were studied.The results showed that it was related to hydrothermal temperature,CS doping amount,adsorption time,pH and PO₄^3-concentration.The maximum loading of BSA and LYS was 185.0301 mg/g and 421.2650 mg/g respectively.Compared with single material,HAp/CS has better loading effect on model protein,and the loading result on LYS is obviously better than BSA.The loading process tends to be equilibrium within 24 h,and the release shows the phenomenon of sudden release before slow release.?3?Finally,the loading,release and bacteriostasis of MCHAp on LYS were studied.The optimum loading of MCHAp on LYS could reach 479.9mg/g,which was better than HAp/CS material.It had antibacterial effect on Escherichia coli before and after LYS loading,and antibacterial effect increased with the increase of concentration,at the same tiame,the release shows the phenomenon of sudden release before slow release.