Preparation And Performance Study Of Natural Polysaccharide-Based Hemostatic Hydrogel

Background and purpose of the study:In daily life,the skin often suffers from various types of physical injuries including trauma,burns and other injuries resulting in bleeding from skin damage,and since the body’s own clotting process is slow,if the bleeding rate is greater than the body’s clotting rate,it is then necessary to introduce hemostatic agents and devices to stop bleeding.Traditional wound dressings are only used to control hemostasis in conventional wounds and are difficult to be applied to the treatment of wounds with uneven surfaces and varying shapes and sizes.Therefore,traditional hemostatic dressings have become difficult to adapt to the needs of current patients.As a biological soft material similar to natural extracellular matrix,hydrogel is soft in texture and will not cause secondary adhesion to wounds,and the synthetic material chosen is non-cytotoxic and irritating.Since the inherent properties of hydrogel are compatible with the ideal wound repair dressing,hydrogel is widely studied and applied in the field of biological wound repair.Injectable hydrogels can be used to fill irregularly shaped and bleeding wounds of different depths due to their unique properties,so various viscous hemostatic hydrogels based on artificial polymers or biomacromolecules have been developed at home and abroad.However,the complicated preparation process and high cost of artificial polymer-based hydrogels have limited the clinical application of hydrogels,so providing a green and low-cost method for the preparation of injectable hydrogels will be of great application significance.In summary,this experiment prepared a natural polysaccharide-based hydrogel with hemostatic injectable green multifunctional by cross-linking water-soluble carboxyethyl chitosan containing amino group with oxidized white and polysaccharide containing aldehyde group by Schiff base under physiological conditions has important research value and application value.Materials and Methods:In this experiment,a natural polysaccharide-based hydrogel with multifunctional integrated hemostatic adhesion and injectable was prepared using acrylic acid-modified chitosan(N-carboxyethyl-chitosan,CEC)and oxidized Bletilla striata polysaccharide(OBSP)as raw materials(CEC-OBSP),which will have the potential and promise for a wide range of applications.The details of the experiments in this thesis are as follows:1.CEC-OBSP gel synthesis and characterization: The monomeric materials CEC and OBSP were synthesized,and the CEC was characterized by NMR hydrogen spectroscopy,thermogravimetric analysis and infrared spectroscopy,and the OBSP material was characterized by NMR hydrogen spectroscopy,thermogravimetric analysis and infrared analysis and the degree of aldolization of white and polysaccharide was detected by oxidation test.Six CEC-OBSP hydrogels with different concentrations were synthesized by adjusting the ratio of amino group to OBSP aldehyde group in CEC.The CEC-OBSP hydrogels were characterized by thermogravimetric analysis,infrared spectroscopy analysis,scanning electron microscopy,and CEC-OBSP hydrogels were tested for gel formation time.2.CEC-OBSP gel performance evaluation: The performance of CEC-OBSP hydrogels was evaluated by porosity evaluation,swelling rate evaluation,water content evaluation,p H response evaluation,injectable performance,and stability performance experiments.The adhesion performance,wound self-adaptability,wound stretchability and hemolytic rate of CEC-OBSP hydrogel were evaluated by pig skin adhesion,joint adhesion and tissue organ adhesion experiments,wound self-adaptability,wound stretchability and blood compatibility experiments.3.Evaluation of in vitro and in vivo hemostatic performance of CEC-OBSP hydrogel: The hemostatic performance of CEC-OBSP hydrogel was evaluated by conducting erythrocyte platelet adhesion test,erythrocyte adsorption rate test,in vitro coagulation index test,whole blood coagulation time test,rat liver injury hemostasis test,rat tail injury hemostasis test,and the hemostatic performance of CEC-OBSP hydrogel was evaluated from microscopic to macroscopic and in vivo to in vitro.The hemostatic properties of the hydrogels were investigated from different perspectives from microscopic to macroscopic,in vivo to in vitro.Results:1.Characterization of the structural and physicochemical properties of CEC-OBSP hydrogels: It was demonstrated by NMR,thermogravimetric analysis and Fourier infrared analysis that chitosan was generated by grafting reaction with acrylic acid through Michael addition reaction,white and polysaccharide was oxidized to aldehydic white and polysaccharide by sodium periodate,and CEC was reacted with OBSP to generate CEC-OBSP hydrogels through Schiff base reaction.The oxidation degree of oxidized white and polysaccharide and the effect of oxidation time on the oxidation degree were tested by hydroxylamine hydrochloride method.The microscopic morphology of the hydrogels was observed by scanning electron microscopy,and the results showed that as the OBSP solution content increased,the R-value became larger and the Schiff base reaction became more complete,thus making the hydrogel cross-linked network more dense.The gel formation time of CEC-OBSP hydrogel increases with the increase of OBSP content,but the excessive amount of OBSP solution makes the gel formation time too long.2.Evaluation of CEC-OBSP performance: The swelling rate results showed that the six groups of CEC-OBSP hydrogels basically reached the swelling equilibrium at about 35 min,and the swelling rates were 2190%±34%,2011%±35%,1861%±44%,1560%±25%,1185%±43%,and 1305%±45%,respectively.The porosity structure results showed 75.3%,70.26%,71.61%,69.54%,62.54%,and 65.31% porosity of the six groups of CEC-OBSP hydrogels,respectively.The results of water content showed that the water content of CEC-OBSP hydrogels were all about 98%.It shows that the hydrogels formed by self-crosslinking have good water retention and abundant water content.The p H dynamic reversible responsiveness of the hydrogels demonstrated that the CEC-OBSP system changed from a gel state to a liquid state under acidic conditions and from a liquid state to a gel state under alkaline conditions.It was proved by injectability experiments that the hydrogel could inject the gel uniformly through 26 G,25 G,22 G,20 G syringes and produce hydrogel filaments uniformly,and could inject the pattern of maple leaves,so the CEC-OBSP hydrogel has excellent injectability performance.The joint adhesion experiments demonstrated that CEC-OBSP hydrogel could completely adhere to the joint,proving that CEC-OBSP hydrogel has good dynamic adhesion.The adhesion experiments on organs and pig skin proved that CEC-OBSP hydrogel has excellent adhesion,toughness and injectability,which is due to various cross-linking forces such as hydrogen bonding,electrostatic interaction and amide bonding between the carboxyl and hydroxyl groups contained in CEC-OBSP hydrogel composition and skin.Wound tensile properties experiments proved that CEC-OBSP hydrogel has excellent tensile properties and toughness.The gel wound adaptivity experiments proved that CEC-OBSP hydrogel has excellent injectability and can be applied to any irregular and different depth of wounds.The hemocompatibility test shows that CEC-OBSP hydrogel has excellent hemocompatibility are less than 3%,which is in line with the national evaluation standard for medical devices.3.Characterization of in vitro in vivo hemostatic properties of CEC-OBSP hydrogel: In vitro coagulation index test proves that CEC-OBSP hydrogel has good coagulation properties and helps to promote blood clotting.The erythrocyte platelet adhesion assay demonstrated that CEC-OBSP hydrogel has good platelet and erythrocyte adhesion.The erythrocyte adsorption rate experiment proved that the erythrocyte adsorption rate of CEC-OBSP hydrogel was better than that of commercially available gauze,and it increased with the increase of OBSP ratio.The in vitro clotting time of CEC-OBSP hydrogel was shorter than that of commercially available gauze by whole blood clotting time experiment,and the clotting time became shorter as the proportion of OBSP increased.It was demonstrated by tail bleeding and liver bleeding experiments in rats that the CEC-OBSP hydrogel group significantly reduced the bleeding volume and clotting time compared with the commercially available gauze group.Conclusion:In conclusion,all the experimental results show that this experimentally prepared multifunctional flexible hydrogel with stretchability,adhesion,injectability and hemostasis will have some potential applications and can be used for the treatment of hemostasis of joints and irregular wounds with depth.