Preparation Of Electrochemical Ion-doped Hydroxyapatite Coating On Bombyx Mori Silk Fibroin Film And Its Osteogenesis Function

Bombyx mori Silk Fibroin(SF)is a natural polymer material with good biocompatibility,excellent mechanical properties,and easy degradation.It is often used in bone tissue engineering scaffolds.Although it is not capable of promoting bone repair by itself,benefit from its rich β-sheet structure,it can effectively bind growth factors and enhance the osteogenic induction performance.Hydroxyapatite(HAp)is the main inorganic component in human bone tissue.It has good biocompatibility,osteoinduction,and osteoconductivity,and is of great application prospects in the field of bone tissue engineering.Studies have shown that the morphology,particle size,and shape of HAp greatly affect its osteogenesis.Electrochemical deposition is a redox coating technology that is capable of reproduce fine multi-level ordered structures on the coating surface.In the field of electrochemical deposition,a research hotspots of bone tissue engineering is to change the morphology of HAp and explore its role in promoting bone function.This is done by changing the electrochemical process and the concentration of ion in the electrolyte.At the same time,trace metal elements play an important role in the function of bone tissue.However,its efficacy has not been taken seriously.Therefore,it is necessary to combine it with hydroxyapatite to achieve better performance in bone tissue repair.Therefore,this study intends to use silk fibroin film as a base material,and deposit hydroxyapatite on its surface by electrochemical deposition with regulate electrochemical process parameters,The research contents and related results of this thesis are as follow:(1)Preparation of ion-doped hydroxyapatite silk fibroin filmBy exploring the conditions,the optimal electrochemical parameters were obtained for the preparation of hydroxyapatite silk fibroin composite membrane(SF-HAp)with uniform distribution and stable appearance.On this basis,the effects of different Zn and Mg concentrations on the deposition morphology were investigated by changing the metal ion concentration in the electrolyte.And an ion-doped hydroxyapatite with a large specific surface area and uniform morphology was obtained.The results show that with the increase of the doped ion concentration,the morphology of Zn-doped hydroxyapatite changes from porous flower clusters to nano-particles,and Mg-doped hydroxyapatite changes from nano-spherical particles to nano-papillary particles.Deposition changes,and particle size increases with increasing concentration.Uniform nanometer particle coatings was obtained when the molar concentration of ions in the mineralization liquid is Mg:Ca=1:4(SF-Mg-HAp)and Zn:Ca=1:10(SF-Zn-HAp).At optimal concentration,doping zinc and magnesium simultaneously with hydroxyapatite(SF-Mg-Zn-HAp)form a spherical shape of foamy glutinous rice.(2)Study on the ability of composite membrane to promote osteoblast proliferation and differentiation in vitroProliferation of hMSCs cells and bone differentiation promotion of ion-doped hydroxyapatite silk fibroin composite membrane was characterized by cell culture experiment.The results of quantitative detection of CCK-8 and ALP showed that the prepared SF-HAp film effectively promoted the proliferation of human bone marrow mesenchymal stem cells.In addition,the electrochemical doping of Zn or Mg ions significantly enhanced the ability of the composite membrane to promote the differentiation of stem cells into osteoblasts.The SF-Zn-HAp membrane yielded best effect promoting bone differentiation in vitro.(3)Study on ectopic osteogenesis in composite membraneSF,SF-HAp,SF-Mg-HAp,SF-Zn-HAp,SF-Mg-Zn-HAp membranes were implanted subcutaneously in rats in in-vivo experiment.And ectopic osteogenesis was observed 8 weeks later.The experimental results show that the six groups of membranes all exhibit good biocompatibility,while SF-Zn-HAp and SF-Mg-HAp membranes doped with Zn and Mg ions alone better promoted the aggregation of collagen fibers at the implantation site.The SF-Zn-HAp yielded best repair effect.In this study,the silk fibroin hydroxyapatite composite membrane was first prepared by electrochemical method,and the effect of electrochemical preparation parameters on the morphology of hydroxyapatite was systematically discussed.Based on this,I expanded the perparation technique by introducing doped ion for constructing synthetic hydroxyapatite with closer structure and composition to human bone tissue structure.My result is show much potential in wider application in bone tissue engineering field,and provided theoretical and practical enlightenment to related researches.