Preparation Of Chitosan/alginate Composite Microspheres And Gel Membrane And Hemostatic Properties Of Composite Microspheres

Chitosan(CS)and sodium alginate(SA)are important biomass materials derived from the ocean.Due to their excellent biocompatibility and biodegradability,they are widely used as biomedical materials.However,because of its own structural nature,single-component materials cannot meet functional requirements.Therefore,the chitosan-sodium alginate biomedical material with modified special structure and performance prepared by blending has become one of the research hotspots in recent years.In this study,a porous composite microsphere containing no cross-linking agent was prepared by microemulsion method combined with thermal induced phase separation(TIPS).Combining a variety of hemostatic mechanisms significantly improves the hemostatic properties of the microspheres.The CS and SA were dissolved in a LiOH/KOH/aqueous urea system by the freeze/thaw method.A dual-network interpenetrating homogeneous chitosan/calcium alginate polyelectrolyte composite gel membrane having pH responsiveness and good mechanical properties is prepared by adjusting preparation methods and raw material ratios.The main results and conclusions were listed below.(1)Firstly,the best preparation conditions of CS@ZnAlg were determined by univariate analysis.The ratio of CS/SA is 10:3,the ratio of ZnCl2 to CS is 10:4,and the emulsifying temperature is 250C.The CS@ZnAlg were particles with a rich porous structure.Their particle size distribution concentrated at 67±12 Em,the surface mean pore size was about 0.22±0.1 ?m,the density is ca.0.064±0.009 g/cm3.The water absorption rate of CS@ZnAlg reached 1850%.The specific surface area(48.9 m2/g)was nearly 49 times that of the commercially available chitosan powder(1.1 m2/g).XPS analysis results show that the surface of the composite microsphere contains Zn2+.Then hemostasis test results show that the in vitro whole blood coagulation time of CS@ZnAlg was reduced to 55 sec from 118 sec of CSMS.Histological analysis and cytotoxicity evaluation show that CS@ZnAlg exhibit no apparent cytotoxicity and cause no side effect to the tissues around a wound.The hemostatic mechanism of CS@ZnAlg was also discussed.(2)The effect of the ratio of CS and SA on the morphology and properties of chitosan/calcium alginate polyelectrolyte composite gel membrane was studied.The SEM of CS/SA11-E,CS/SA11-Ca and CS/SA11-W shows that the surface pore size of CS/SA11-E is uniform and the pore size is ca.11.5±3.1 ?m.However,the surface of CS/SA11-Ca shows no pore structure and is attached to a large amount of particles.The CS/SA11-W has a smooth surface with a mean pore size of 24.5±7.8 ?m.By regulating the ratio of CS/SA,the pH swollen response of CS/SA-E at different ratios was demonstrated.CS/SA11-E can relieve the unidirectional pH response of CS/SA21-E and CS/SA12-E The equilibrium swells at pH 3 and pH 10 are 3.6 and 1.6,respectively.The mechanical property test results show that the tensile strength ?b,elongation at break ?b and Young's modulus E of CS/SA11-E are 0.14 MPa,67.74%and 0.18 MPa,respectively;the compression modulus E is 0.68 MPa,showing good Tensile properties and fatigue resistance.However,CS/SA11-W is too low in mechanical strength due to hydration strength and cannot be tested.