Preparation And Properties Of Silk Fabric Reinforced Silk Fibroin Composite

Silk fiber and its fabric have excellent mechanical properties and good biocompatibility.In recent years,as reinforcements of composite material,silk fiber and its fabrics have been applied to research and construction of artificial vascular,meniscus and wound covering materials.This thesis obtained a kind of silk fabric reinforced silk fibroin composite material through casting different concentrations of regenerated silk fibroin/formic acid(FA)solution onto degummed silk plain woven fabrics pretreated by different concentrations of FA at different compound ratios.Tests and analysis of mechanical properties,structures and thermal properties of the material were systematically conducted.By adding anhydrous Ag NO3 particles into regenerated silk fibroin/FA solution and choosing the best preparing parameters of composite,silver-loaded antibacterial composite was prepared.The size,shape and distribution of silver particles and their effect on the composite's antibacterial properties,mechanical properties and structures were also studied in order to explore its potential in wound coverage materials.The effect of FA pretreatment on tensile properties of silk fabric was found significantly different when the concentration of FA varied.The effect of 98% FApretreatment was the strongest and 88% FA showed weaker effect than the former while 78% FA has the smallest effect.After 98% FA pretreatment,fabric showed a dramatic shrinkage and nearly 85% breaking strength lost.However,the elongation was 2 times of the original and reached around 27%.As to 88% FA pretreatment,breaking strength lost 50% but elongation at break increased to 33%.Considering 78% FA pretreatment,breaking strength of silk fabric was slightly less than 20 MPa and elongation increased to 17%.Effects of concentrations of regenerated silk fibroin/FA solution,compound weight ratios and FA pretreatments of fabrics on the properties of composites were mainly discussed.88% FA pretreatment,fabric/silk fibroin compound weight ratio at 1:2 and 4% regenerated silk fibroin/FA solution were the best parameters.Under this condition,the mechanical properties of composite came the best with breaking strength,breaking elongation and modulus reaching 41.55 MPa,6.35% and 1.85 GPa.The tensile fracture cross section was very smooth and fabric was closely connected with regenerative silk fibroin as there was no gap between them.From X-ray diffraction(XRD)results,no matter the concentrations of regenerated silk fibroin/FA,compound ratios or FA pretreatments of fabrics,the crystallization structure of composites was mainly ?-sheet.When the content of regenerated silk fibroin in composites increased,the thermal decomposition temperature of composite decreased then.The antibacterial experiments showed that silver-loaded fabric reinforced silk fibroin composite had excellent antibacterial effect on Staphylococcus aureus and Escherichia coli.The antibacterial rate of composite with 1% silver content reached 100%.The deacidized silver particles presented nanoscaled between 100 nm ~ 300 nm when composite contained a low content(less than 2%)of silver.Fourier transform infrared spectroscopy(FTIR)results indicated that silver particles did not significantly change the secondary structure of composite.Also,there were no changes of mechanical properties due to silver particles.The preparation of silver-loaded silk fabric reinforced silk fibroin composite material not only overcame the brittleness of pure regenerated silk fibroin film but also embraced excellent antibacterial properties,which provided an innovative idea for research and development of biomedical material in wound coverage.