Preparation And Characterization Of Tussah Silk Fibroin And Hydroxyapatite Composite Biomaterials

With the development of society,the global aging process is also increasing.More and more people are suffering from osteoporosis,osteoarthritis,rheumatoid arthritis and other related diseases.These diseases affect both the self-care ability and the quality of people's life.But the limitations of auto graft and allograft induce a lot of difficulties and obstacles in the treatment of diseases.Therefore,the preparation of biomedical materials with bioactive bone tissue has become one of the main tasks in medicine and biology.In recent year,the research on the preparation of bone tissue biomedical materials with hydroxyapatite(HA)and silk fibroin powder has attracted more and more attention,however,few study on the total mixing of HA and tussah silk fibroin is reported.In addition,because of poor compatibility of the inorganic hydroxyapatite and silk fibroin,in this study,the dispersivity of HA and silk fibroin would be improved by the reaction of the silane coupling agent and HA,and then HA was mixed with the tussah silk fibroin solution to enhance the compatibility of composite materials.At present,the degumming,dissolution method and technology of silkworm is mature,but these methods and techniques are not suitable for tussah.Therefore,the degumming and dissolution process of the tussah has become a research key for the application in the fields of tussah silk fibroin biomaterials.It is necessary to use a green and mild method to obtain tussah silk fibroin solution with non-toxic biological properties.In the second chapter of the thesis,wild tussah was selected as the raw material to obtain silk fibroin solution.The degumming and dissolution of tussah silk fibroin and its influencing factors were disussed,as well as the problems that should be paid attention to in the process of purifying dialysis.The results showed that the optimal pH range of the degumming was 8-11.The optimal solution condition was obtained,the tussah was heated for 3 h in 0.5%Na2CO3 solution.The fibroin fiber was dissolved in molten tetrahydrate calcium for 5 h at 105?,and the silk fibroin solution containing calcium was obtained.In the process of purification and dialysis,the silk fibroin aqueous solution was obtained by the dialysised purification of the flowing water for 2 days and deionized water for 1 day,and then placed in the refrigerator at 4? for use.In the third chapter of thesis,to improve the dispersion of hydroxyapatite and avoid agglomeration,three different silane coupling agents(KH550,KH560,and KH580)was selected to modify hydroxyapatite.The structure and property of the modified hydroxyapatite were characterized with FTIR,SEM,XRD,TGA,water contact angle,and other characterization methods.The results showed that the silane coupling agent was successfully modified with hydroxyapatite,and the best dosage of silane coupling agent modified hydroxyapatite was determined.In the paper the fourth chapter,the hydroxyapatite and silk fibroin composite materials were prepared using solution blend method,and their mass ratio was 7:3.After ultrasonic dispersion,the composite materials were obtained by freeze drying of biological.The structure and properties of the composite materials were characterized by FTIR,XRD and so on.The results showed that the two substances mixed very well.The prepared composite biomaterials were placed in SBF,the results showed that the mass of the composite biomaterials increased and the pH value of the solution hardly change,which indicated that the composite biomaterial obtained in this study had good biocompatibility.In the degradation liquid,the extension of time and degradation rate gradually increased,this indicated that the compound biomaterial could meet the needs of the implantation.