| In tissue engineering,it is important to simulate extracellular matrix(ECM)to promote cell adhesion and regulate cell behavior.Therefore,the structural design and construction of tissue engineering scaffolds has become an important field in the development of biomedical materials and regenerative medicine research.The natural extracellular matrix is a nanofiber gel network composed of collagen,elastin,etc.,having a fiber diameter of 50 to 500 nm.Electrospinning is a technique that can quickly prepare a large amount of ultrafine fibers.By adjusting the parameters,the fibers with different diameter(nano to micro)can be fabricated.The fiber scaffold prepared by this technique can well mimic the structure of the natural extracellular matrix,has a positive effect on cell adherence,growth and spread,and can promote tissue regeneration.Silk fibroin(SF)extracted from silk by degumption is composed of various amino acids,the main components of it are glycine(Gly),alanine(Ala)and serine(Ser).SF has been highly valued by researchers because of its unique properties such as excellent biocompatibility,mechanical controllability and non-immunogenic properties.However,silk fibroin scaffolds are difficult to process and have poor anticoagulant properties.In addition,the mechanical properties of silk fibroin are not sufficient to support the construction of tissue engineering scaffolds that meet ergonomic standards.Therefore,the electrospinning technique is used to prepare a silk fibroin composite scaffold which is excellent in mechanical properties and can simulate an extracellular matrix by structural design and material modification.The comprehensive performance of the scaffolds was evaluated from the aspects of biomechanics,biodegradability,cell viability,and hemocompatibility.The main research content of this topic includes the following points: 1.Blended nanofibers of silk fibroin(SF)/degradable polyurethane(LDI-PEUU)were prepared using conventional random electrospinning techniques.Basic chemical characterization of infrared spectroscopy(FTIR)and X-ray diffraction(XRD)results showed that the blend did not change the molecular structure of SF and PEUU.The mechanical tensile properties test suggested that the mechanical strength was apparently increased with the addition of LDI-PEUU.Short-term biodegradability experiments suggeated that the composite of materials can regulate the nanofibers’ degradation rate.In vitro cell compatibility experiments showed that the composite nanofiber membrane showed higher cell proliferation characteristics.2.To study the effects of different microstructures on the mechanical properties,biodegradability and cell behavior of nano-micro fiber,silk fibroin composite scaffolds(OSS)with multi-layer micro-nanofiber structures were prepared by electrospinning equipment.Scanning electron microscopy(SEM)showed that the fiber morphology of OSS was not obvious,and it was composed of fiber and membrane morphology,which may micmic the structure of natural extracellular matrix.3.To increase the stability of micro-nanostructure silk fibroin composite scaffolds with different microscopic morphology,the scaffold was crosslinked by using natural crosslinking agent,and the performance of the scaffold was evaluated.The SEM results showed that the cross-linked stent fiber morphology remained intact.FTIR and XRD demonstrated that the conformation of the scaffold changed after crosslinking,and silk fibroin began to switch to ?-fold.Additionally,the chemical modification of the nanofibers significantly enhanced the expression of the composite nanofiber membrane on human umbilical vein endothelial cells(HUVECs).In addition,the chemical grafting process obviously changed the original morphology of the multi-layer structure composite nanofibers,and the fiber morphology was more obvious,the mechanical tolerance of the chemically modified fiber film was not significantly changed.This provides a possibility for the application of scaffolds in tissue engineering. |
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