Silk Fibroin Nanofiber Regulated Synthesis Of Iron Oxide Nanomaterial And Its Mechanism Study

Iron is abundant in nature. Its oxides exhibit excellent performances in electricity, magnetism and others; furthermore, they have been widely used in energy storage, biomedical applications and so on. However, water-dispersibility and energy recession during charge-discharge process remain key problems to be solved. Besides, silk fibroin has been widely applied in different fields such as tissue regeneration, drug release, and photo-electric application due to its controllable nano-structure and secondary conformations. Especially in recent years, silk fibroin as template has shown promising future in regulating nanomaterial’s fabrication.In the present thesis, silk fibroin with specific nanostructures was used to tune the synthesis of iron oxide with different morphologies and functions. Through investigating the forming processes, the mechanisms for controlling the nanostructures of the nanomaterials were revealed to improve their feasibility in magnetism, and biomedical applications. Several detailed results are showed as follows:(1) Silk fibroin nanofiber-templated preparation of olive-like Fe3O4/C hollow nanomaterials. Olive-like Fe3O4/C was prepared without any other chemical agents. The morphology, size and structure of the final nanomaterials could be tuned by varying the concentration of silk fibroin and the reaction time. Possible formation mechanism was also proposed based on various characterizations. The prepared Fe3O4/C hollow nanomaterial has been evaluated as anode materials for lithium ion batteries, showing that Fe3O4/C hollow nanomaterial has a good electrochemical performance.(2) Graphene-silk fibroin nanofiber complexe-tempaled preparation of Fe2O3/Graphene nanorods. Silk fibroin can be assembled into nanofiber with the assistance of the graphene oxide’s reduction by hydrazine. So, graphene-silk fibroin nanofiber complexe was used to template the preparation of Fe2O3/Graphene nanorods through hydrothermal method. The possible formation mechanism was proposed to improve various characterizations of the nanorods. The nanorods showed excellent electrochemical performance, suggesting promising application as anode material for lithium ion batteries(3) Silk fibroin-templated preparation of Fe3O4/SF nanomaterials. Silk fibroin nanofiber, assembled in EG, was used to prepare Fe3O4/SF nanoparticles with uniform morphology via a solvethermal method in which the size of the Fe3O4/SF nanoparticles was tuned by varying the concentration of silk fibroin. A possible mechanism was proposed to clarify the critical effect of silk fibroin in regulating the morphology and stability of the nanomaterials. Due to its strong magnetism, the obtained Fe3O4/SF nanoparticles were also fabricated as MRI and bioseparation agent.(4) Preparation of Fe3O4/SF nanochains with silk fibroin as template under external magnetic field. Silk fibroin nanofiber, assembled in EG, was used to prepare Fe3O4/SF nanochains with uniform morphology through solvethermal method under external magnetic field. A possible formation mechanism was suggested and an enhanced magnetic property was achieved, compared with previous Fe3O4 nanomaterials.In summary, iron oxide nanomaterials with different morphologies and functions were successfully prepared through simple method with the assistance of silk fibroin. The applications of the obtained iron oxide nanomaterial in magnetism, biomedical field and electricity were also studied. The corresponding formation mechanisms of the different iron oxide nanomaterials were revealed through studying the forming processes. As a result, silk fibroin is an ideal bio-template for regulating the formation of iron oxide nanomaterials with different morphologies and functions, which expands the application of silk fibroin in nanomaterials.