Facile Preparation And Characterization Of New Crosslinked Chitosan Sponges As Well As Their Application Potential As Hemostatic Dressings

Chitosan(CS),as a biocompatible cationic polysaccharide polymer,has versatile attractive characteristics such as low toxicity and antimicrobial activity.Chitosan has been widely used in food industry,environment protection and clinical appications.Fabricated as medical device in forms of sponge,bandage,granule,or non-woven fabric,chitosan was approved to stop bleeding and promote wound healing in clinic.However,unstable mechanical strength of chitosan sponge as hemostatic dressings limited its clinical applications.In this investigation,we aimed at the development of new cxosslinked chitosan sponges as hemostatic dressings,which maintained their flexibility and had improved mechanical strength.We chose a series of crosslinkers which contain diglycidyl ether functional group and obtained smooth,evenly,and slightly yellowish chitosan sponges.Compared with the uncrosslinked chitosan sponges(without addition of crosslinkers as Control),the crosslinked ones(as Sample)showed a similar flexibility and a better stability(appearance and morphology)in aqueous solution.To investigate the potential of the crosslinked chitosan sponges as hemostatic dressings,the porosity,water absorption,and blood coagulation time of the sponges were measured.The results revealed that the sponges could be used as hemostatic device,and prompted us to further study blood clotting of the sponges.The whole blood from cynomolgus monkey was applied onto the top of the chitosaa sponge,and blood stratification was observed by naked eye in the cross section of the sponge samples where three colored layers were formed after the whole blood was absorbed into sponges,which may suggest that red blood cells involved hemostatic process for the sponges as hemostatic dressings,visualized by using scanning electron microscope(SEIM).It may indicate the potential applications for the sponges for heparinated blood as hemostatic dressing.Meanwhile,with different concentrations of chitosan,and different types and ratios of crosslinkers,the preparation conditions of the sponge were optimized and the samples were prepared in pilot scale and characterized.The results made us believe that the covalently crosslinked chitosan sponge prepared in this study has a potential as hemostatic dressing and is worth of further development.