Preparation And Application Of Hydroxyapatite Derived From Mussel Shell

Mussel shells have unique biological evolutionary microstructures and are excellent raw materials for the preparation of hydroxyapatite.In order to improve the comprehensive utilization value of discarded shells,this thsis used mussel shells as raw materials to prepare hydroxyapatite,and studied the preparation conditions and morphology of high-purity hydroxyapatite;compounded with chitosan to prepare hydroxyapatite/chitosan hydrogels,the preparation conditions of composite hydrogels,the effect of hydroxyapatite on the physicochemical properties and antibacterial properties of hydrogels were studied;The preparation conditions,catalytic activity and stability of immobilized enzymes were studied,which provided a new way for the development and utilization of shells.(1)Optimization of conditions and structural characterization of hydroxyapatite preparation from mussel shells: Biomass calcium carbonate raw materials were obtained by heat-treating mussel shells,and reacted with diammonium hydrogen phosphate to prepare hydroxyapatite.The effects of shell powder particle size,concentration of feed liquid,reaction temperature,reaction time and initial p H of reaction on the content of hydroxyapatite in the product were studied,and a response surface optimization experiment was carried out on the basis of single factor experiment.The research results show that the reaction temperature has a greater influence on the hydroxyapatite content,followed by the concentration of the feed solution,and the reaction time has a smaller influence.The optimal process conditions are shell powder 600 mesh,feed concentration 0.06 g/m L,reaction time 7 h,reaction temperature 94 ℃,initial reaction p H 9.5,the content of the obtained hydroxyapatite reaches 98.21%,and the microscopic morphology is nanometer Plate-like enriched spherical structures.(2)Preparation and properties of hydroxyapatite/chitosan hydrogels: Using chitosan as monomer,hydroxyapatite as inorganic additives,and glutaraldehyde as cross-linking agent to prepare composite hydrogel materials,research the effects of chitosan concentration,glutaraldehyde addition and hydroxyapatite addition on the gelation time and properties of the gel materials were investigated,and the antibacterial properties of the composite hydrogel materials were investigated.The results show that: when the concentration of chitosan is lower than 0.75%,the gel cannot be formed;when the concentration is between 1% and 2%,the gel time is shortened with the increase of the concentration;when the concentration exceeds 2%,the gel time is too short poor operability.When the concentration of glutaraldehyde is between 5%and 30%,the gel formation time decreases with the increase of the amount of glutaraldehyde.When the addition amount of hydroxyapatite is 1%,the gel formation time is the shortest.Within the operable range,the hardness of the hydrogel increased with the increase of the chitosan concentration,and the swelling degree was opposite.The amount of glutaraldehyde affects the cross-linking degree of the gel.With the increase of the amount of glutaraldehyde,the hardness of the hydrogel increases,and the swelling degree decreases with water absorption.When the amount of hydroxyapatite added is between 0.5% and 1.0%,with the increase of the amount of hydroxyapatite,the hardness of the gel increases and the swelling degree of the gel decreases;while between 1.0% and 2.0% However,hydroxyapatite reduces the hardness of the gel and increases the swelling degree.In terms of antibacterial properties,the antibacterial rate of the gel material with the addition of 1% hydroxyapatite increased by 1.5%,and the antibacterial rate of the gel material with the addition of 2% hydroxyapatite increased by 3.5%.It has good biocompatibility and adsorption performance,and has a certain enrichment effect on biological materials.The addition of hydroxyapatite improves the mass transfer efficiency of chitosan in the antibacterial process,thereby improving the antibacterial effect.(3)Preparation of hydroxyapatite/chitosan gel microspheres and enzyme immobilization research: Hydroxyapatite/chitosan gel microspheres were prepared as immobilized enzyme carriers,and the effects of different immobilization sequences on the enzyme were compared.The loading efficiency,enzyme catalytic activity and stability of the enzyme immobilized on hydroxyapatite/chitosan gel microspheres were investigated.The results show that the sphericity of gel microspheres is proportional to the concentration of ethanol-sodium hydroxide solution,and relatively complete gel microspheres can be rapidly formed at a concentration of 20%.In the order of immobilization,the effect of the hydroxyapatite/chitosan gel microspheres is better,and the catalytic activity is retained.In terms of loading efficiency,the saturated enzyme loading capacity of hydroxyapatite/chitosan hydrogel reached 363.379 mg/g,and the loading rate was81.04%.In terms of stability,the optimum temperature of the gel microsphere-immobilized enzyme at 50 °C is slightly higher than that of the free enzyme at 45 °C,and the optimum p H has not changed,but the enzyme activity is higher than that of the free enzyme.The integrity of the test and the mechanical stirring test were 90% and 75%,respectively.After five times of repeated use,the enzyme activity remained 76.72%,indicating that the immobilized enzyme had good stability.The paper has 29 figures,11 tables,and 110 references.