Preparation And Properties Of Human Hair Keratin/nano-silver Antibacterial Bioporous Scaffolds

Natural keratin materials are widely found in animal hair,horns,feathers and human hair and nails.Waste wool from wool spinning industry and animal hair from animal husbandry are important sources of waste keratin.In view of its good biocompatibility and biodegradability,keratin has become one of the hot issues in tissue engineering in recent years and has been widely used in medicine,food and other fields.In this study,keratin macromolecules were extracted from human hair fibers by reduction method,and then keratin/nano silver antibacterial porous scaffolds(K/Ag)were prepared by different silver loading methods,including keratin/nano silver blend antibacterial porous scaffolds(K/Ag_in)and keratin surface attached nano silver biological porous scaffolds(K/Ag_sur).In order to improve the water resistance of porous scaffolds,EGDE crosslinking agent was used for the first crosslinking and oxygen crosslinking method for the second crosslinking.The porous scaffolds were characterized by SEM,EDX,porosity,FTIR,XRD,TG,water absorption,swelling and tensile mechanical properties.The results showed that silver free pure keratin porous scaffolds(Ag-0)and K/Ag_in scaffolds were similar in morphology,with different pore structures,good pore connectivity and microporous structure on the wall of macropore,while K/Ag_sur scaffolds had decreased pore connectivity.The surface silver content of K/Ag_sur scaffolds was higher than that of K/Ag_in scaffolds.The porosity of Ag-0 scaffolds was the highest,while that of K/Ag scaffolds decreased slightly with the increase of nano silver loading.When nano silver loading was the same,the porosity of K/Ag_in scaffolds was slightly higher than that of K/Ag_sur scaffolds.Oxygen crosslinking improved the water resistance of scaffolds.There was no chemical effect between keratin and nano silver,only physical adsorption.Crosslinked scaffolds have higher thermal stability than uncrosslinked scaffolds,and K/Ag scaffolds have higher thermal stability than Ag-0 scaffolds.The water absorption of the scaffolds was not related to the amount of silver,but it was related to the way of silver loading.Ag-0 scaffolds had the highest water absorption,and K/Ag_in scaffolds had higher water absorption than K/Ag_sur scaffolds.The swelling rate of Ag-0 scaffolds is relatively high,and that of K/Ag_in scaffolds is higher than that of K/Ag_sur scaffolds.The tensile property of K/Ag scaffolds is higher than that of Ag-0 scaffolds,and that of K/Ag_in scaffolds is higher than that of K/Ag_sur scaffolds.In addition,antibacterial test,in vitro degradation,drug release and biocompatibility of different porous scaffolds were studied.The results showed that the antibacterial effect of K/Ag_sur was better than that of K/Ag_in.The higher the silver loading,the slower the degradation rate of scaffolds.The drug release of each kind of K/Ag_in scaffolds showed a slow rising trend,which was lower than that of K/Ag_surscaffolds in the initial stage.With the increase of the soaking time of the scaffolds in each system,the drug release of K/Ag_in scaffolds exceeded that of K/Ag_sur scaffolds of corresponding concentration,and the overall release of each kind of K/Ag_in scaffolds showed a slow and sustained trend.Cells were cultured on the scaffold for one day,the cell density was not large,and they could adhere and proliferate on the scaffold.With the extension of culture time,the number of cells increased significantly,and migrated to the pores.Compared with Ag-0 scaffold,the other six K/Ag scaffolds had no inhibition on the growth of cells,which indicated that the six silver scaffolds had good biocompatibility and no cytotoxicity.