Evaluation Of Hemostatic And Antibacterial Properties Of Functionalized Three?dimensional Dendritic Mesoporous Silica

Massive hemorrhage is the main cause of death in various accidents and surgical treatment.On the battlefield,50% of battlefield casualties are caused by uncontrolled bleeding and complications caused by hemorrhage.Even if the injured can be sent to the hospital in time for emergency treatment,massive blood loss can still lead to acidosis,coagulation dysfunction and infection,resulting in septicemia and multiple organ failure,and eventually lead to death.How to effectively stop bleeding in the prime time after bleeding is of great significance.In recent years,a variety of new hemostatic methods and materials have been widely studied,including new inorganic hemostatic materials,bioactive hemostatic materials and organic polymer hemostatic materials.And they have been used in clinical and war wound treatment.However,the hemostatic materials used at present have some defects.Inorganic hemostatic agents can lead to tissue thermal injury,vascular endothelial damage,poor biodegradability,and they can remain in the vascular lumen and lungs which can lead to thrombosis;when organic polymer hemostatic materials is used for severe traumatic bleeding,its hemostatic effect is very limited;bioactive hemostatic agents are not easy to preserve,and have the risk of immunogenicity and virus contamination.Meanwhile,the hemostatic materials used in clinic have no antibacterial properties.The ideal hemostatic material should have the following characteristics:(1)it is suitable for all kinds of active bleeding wounds with good hemostatic effect;(2)it is convenient to use;(3)it has good biocompatibility and is easy to degrade in vivo;(4)it has antibacterial properties.Mesoporous silica has the advantages of good biocompatibility,low cytotoxicity,good thermal stability and adjustable surface charge.It can also effectively resist infection by loading antibiotics.In this study,three?dimensional dendritic mesoporous silica were modified with thrombin and vancomycin to enhance their hemostatic and antibacterial properties and a new hemostatic material with both hemostatic and antibacterial functions was prepared.Part One: Preparation of functionalized three-dimensional dendritic mesoporous silica materials.In this project,we chose a new preparation method(nanoparticles-oil-water stratification two-phase method)to synthesize three-dimensional dendritic mesoporous silica nanoparticles.We chose mesoporous silica spherical nanoparticles(MSN)with 7nm pore diameter and 135 nm particle size as the basis,firstly loaded vancomycin in the pore channel of mesoporous silica,then modified its surface with polydopamine to synthesize vancomycin loaded mesoporous silica(MSN-Van-DOPA).Finally,MSNVan-DOPA was further modified with thrombin to prepare mesoporous silica loaded with thrombin and vancomycin(MSN-Van-DOPA-Tro).The four kinds of mesoporous silica nanomaterials were observed by scanning electron microscope(SEM)and transmission electron microscope(TEM)to determine the drug loading.We found that the synthesized MSN is homogeneous and monodisperse spherical nanoparticles with MSNy pores on its surface that can be loaded with drugs.Vancomycin is loaded through those pores,encapsulated with polydopamine,and adhered to thrombin by polydopamine adhesion.A thin film can be observed on the surface of MSN-Van-DOPA-Tro,indicating that thrombin has been successfully loaded.Part Two: Study on the hemostatic properties of functionalized three-dimensional dendritic mesoporous silica materials.The mesoporous silica loaded with thrombin combines the advantages of thrombin and mesoporous silica,and its hemostatic effect should be better.We evaluated the hemostatic properties of MSN-Van-DOPA-Tro in vitro by measuring clotting blood test(CBT)and clinical basic blood coagulation tests(APTT and PT tests).The coagulation properties of functionalized three-dimensional dendritic mesoporous silica materials were evaluated by establishing a rat model of hepatic hemorrhage.The effect of nanohemostatic materials on the proliferation of MC3T3 was detected by CCK-8 to evaluate its biocompatibility.Through the study,we found that four kinds of mesoporous silica materials can effectively reduce the time of clotting blood test(CBT),MSN-Van-DOPA and MSN-Van-DOPA-Tro have a more significant effect on CBT.MSN-Van-DOPA and MSN-Van-DOPA-Tro can effectively reduce APTT and PT,while the effects of MSN and MSN-Van on APTT and PT are not obvious.In the rat model of hepatic hemorrhage,MSN-Van-DOPA and MSN-Van-DOPA-Tro,can significantly reduce the amount of bleeding and reduce the bleeding time.The compatibility test showed that the cytocompatibility of MSN-Van-DOPA-Tro was very good,and there was no cytotoxicity at the concentration of 200 ? g / ml.Part Three: Study on the antibacterial properties of functionalized threedimensional dendritic mesoporous silica materials.Ideal hemostatic materials must not only promote blood coagulation,but also have antibacterial properties.Mesoporous silica nanoparticles can be used as carriers of antibiotics and other small molecular drugs through their pore structure.Vancomycin can inhibit and treat methicillin-resistant Staphylococcus aureus infection.We loaded vancomycin into the pores of mesoporous silica nanomaterials and encapsulated with dopamine to ensure the antibacterial effect.We evaluated the antibacterial properties of functionalized three-dimensional dendritic mesoporous silica materials.The minimum inhibitory concentration(MIC)of three groups of mesoporous silica nano-materials(MSN,MSN-Van,MSN-Van-DOPA-Tro)were detected,and the antibacterial properties of nano-hemostatic materials were characterized by tissue plate method.Through the experiment,we found that the MIC of MSN-Van-DOPA-Tro against methicillin-resistant Staphylococcus aureus was 16 ? g / ml.The antibacterial activity was characterized by tissue plate method.MSN-Van,MSN-Van-DOPA-Tro could inhibit the proliferation of Staphylococcus aureus.