Preparation Of Cross-Linked Porous Starch And Chitosan Composite And Study On Hemostatic Properties

Natural disasters,wars,surgeries and traffic accidents are the main causes of bleeding.In recent years,biological hemostatic materials have shown great potential in hemostasis.Some breakthroughs have been made in the speed and function of hemostasis,but there are still many deficiencies and need to be improved.Porous starch has attracted much attention in the application of hemostatic materials because of its excellent properties,such as low toxicity,biodegradability,hydrophilicity and absorbability.Besides,chitosan has also many excellent biological properties,such as biocompatibility,biodegradability,non-toxicity,antibacterial activity and hemostasis.Therefore,the combination of two hemostatic materials will have potential advantages in hemostatic performance.In order to prepare a new type of hemostatic agent with high efficiency,safety and low cost,the experiment was carried out with porous starch and chitosan as raw materials:Using corn starch as raw material,porous starch(PS)was prepared by enzymatic hydrolysis method.When the the ratio of liquid volume to corn starch mass was 6 : 1,the mass ratio of saccharifying enzyme to amylase was 3 : 2,ultrasonic power was 550 W,enzymolysis time was 10 h,and the amount of enzyme was 5%,the optimum water absorption and expansion rate of porous starch were 120.49% and212.58% respectively.Cross-linked porous starch(SPS)was prepared by using sodium trimetaphosphate as cross-linking agent,when the volume ratio of porous starch to liquid is 30%,the reaction temperature is 55 ?~60 ?,the mass ratio of crosslinking agent to starch is 0.04:1,the pH value of the reaction system is 9.0,and the crosslinking time is 50~60 min.The water absorption and expansion rate of cross-linked porous starch were 154.33% and 239.14%,respectively.Chitosan(CS)was degraded by hydrochloric acid method.The degraded chitosan(molecular weight 100-110 KDa)was crosslinked with porous starch by sodium trimetaphosphate(STMP)and was investigated by single factor.On the basis of single factor,the ratio of solid to liquid(10.0%,12.5%,15.0%),the mass ratio of porous starch to chitosan(1:1,2:1,3:1),the mass ratio of STMP to porous starch and chitosan(6%,8%,10%)as the independent variable,taking the water absorption rate as the response value,and the response surface optimization was carried out.Theoptimum conditions are as follows: the ratio of solid to liquid is 12.5%,the mass ratio of porous starch to chitosan is 2%,and the mass ratio of STMP to porous starch and chitosan is 8.0%.Three parallel experiments were carried out under this condition,the average water absorption was 145.6%,and the binding rate was 71.30%.Scanning electron microscope(SEM)was used to observe that the surface of porous starch and cross-linked porous starch particles were covered with pores,and the surface of cross-linked porous starch-chitosan(SPC)was covered with a large amount of chitosan.Furthermore,Fourier transform infrared spectroscopy(FTIR)showed that there were no new absorption peaks in the infrared spectra of PS and SPS compared with the original starch.And the characteristic absorption peaks of chitosan appeared in SPC.X-ray single crystal diffraction scanning(XRD)showed that cross-linking of porous starch and cross-linking of porous starch with chitosan occurred in the crystalline region of starch.Male SD rats,weighing 200~220 g,were used as experimental rats.In the whole coagulation kinetics experiment,the cross-linked porous starch-chitosan could form larger blood clot in the same time compared with PS SPS.In the experiment of interaction with red blood cells,compared with PS,SPS,the surface of SPC can adsorb more red blood cells,and this adsorption is clustered and aggregated.During the interaction between SPC and sodium citrate anticoagulant,it was found that a large number of blood cells were adsorbed on its surface,and even a small number of platelet synapses were produced.We concluded that the hemostatic mechanism of SPC is the synergistic hemostatic effect of porous starch and chitosan.The hemostasis time of SPC was the shortest,which was 164.42 s(1 cm),147.25 s(2 cm)and 145.20 s(liver injury)in the experiment of severing tail and liver injury in rats.SPC showed a better hemostatic effect.