| Chitosan(CTS)is cheap and easy to obtain.It has good hemostatic performance and biocompatibility.It can be widely used for antimicrobial and wound healing.After modification by N-alkylation,CTS not only retains its excellent activity,but also enhances its hemostatic performance.Bletilla striata polysaccharide(Bsp)is a water-soluble polysaccharide extracted from traditional Chinese medicine Bletilla striata,which can astringe hemostasis,detumescence and muscle-building,and has a variety of physiological activities.In this paper,a new N-alkylated chitosan(N-CTS)/bletilla baicalensis polysaccharide composite(N-CTS/Bsp)was prepared by combining the properties of the two materials,and the properties of the composite were studied.On the basis of N-alkylation modification of chitosan,three formulations of N-CTS/Bsp were prepared,and their performance evaluation and physicochemical characterization were carried out respectively.The results were as follows:1.Firstly,the aldehyde group in dodehyde was linked to the amino group in chitosan by Schiff base reaction to form a carbon-nitrogen double bond.Then,the carbon-nitrogen double bond was reduced by sodium borohydride solution to obtain a stable N-CTS.Fourier transform infrared spectroscopy(FTIR)confirmed that alkyl chain was successfully introduced into chitosan molecule.Elemental analysis showed that the contents of C and N in CTS and N-CTS were 65.56%(C),10.57%(N);66.77%(C)and 9.69%(N),respectively.The degree of substitution of N-CTS was5.731%.The degree of substitution is low,which meets the experimental expectation.2.N-CTS composite freeze-dried powders with different ratios of raw materials(1?N-CTS:Bsp?4)were prepared by ion cross-linking and freeze-drying.SEM results showed that the freeze-dried powders had porous structure and water absorption was greatly affected by the ratio of the two raw materials.In order to absorb liquid quickly,release active substances quickly and be more suitable for irregular wounds,the optimum preparation conditions of composite freeze-dried powder were determined by considering all the indexes of composite freeze-dried powder:the ratio of N-CTS to Bsp was 4:1,the total concentration of raw material was 2 g/L,and the positive-negative charge ratio was 20:1.At this time,the yield of the product was89%,the water absorption capacity was 327%,the effect lasted for a long time,and the degradation rate was 59.4%in 4 weeks.The particle size was concentrated at14.79?m,which was similar to the size of red blood cells and had obvious bacteriostatic effect.It was suitable for the application of biomaterials.3.Composite film and composite sponge with different Bsp content(5%-50%)were prepared by freeze-drying method.The material has excellent water absorption,bacteriostasis,degradation and other activities.The composite material can absorb water quickly after contacting with the liquid,wherein the composite membrane rapidly swells,and the composite sponge gels to a certain extent and has strong adhesion,both of which can continuously provide a moist sterile environment for the contact site to meet the requirements of biological materials.Considering the characteristics of composite materials and the characteristics of wound area,depth and bleeding volume,N-CTS composites with 90%of the composite materials are most suitable for use as hemostatic materials.At this time,the composite membrane can absorb 4.69 times its own weight of water,the water vapor permeability is 1.14kg/(24 h·m~2),and the degradation rate is 51.2%within five weeks.The surface of the composite membrane is convex and concave and porous,which is conducive to liquid adsorption.The composite sponge has abundant network structure and can absorb23.75 times its own weight of water.Its water vapor permeability is 3.09 kg/(24 h·m~2).It can degrade 85.2%in five weeks and its porosity is 89.22%.It fully demonstrates that the composite material has fast and lasting effect and has the application potential of hemostatic materials. |
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