Synthesis Of Polylutamic Acid Dendrimer And Its Application In Anti-cancer And Thrombolysis Combined Treatment

Cancer and thrombus often do not occur alone in clinic.The tissue factors?TFs?produced by cancer cells and the cancer treatment process,including chemotherapy,surgery and long-term bed rest,can promote the formation of thrombosis,leading to thrombosis complications becoming the second major cause of death in cancer patients.Moreover,thrombosis will also lead to the occurrence of hypoxia,necrosis and other lesions at the site of thrombus,and increase the probability of cell carcinogenesis.Therefore,the combined treatment of cancer and its thrombosis complications has attracted researchers'attention.However,anticancer drugs tend to have large toxic,side effects and low utilization rate,while the commonly used thrombolytic drug nattokinase?NK?is easy to lose its activity,short half-life,and prone to bleeding when used in large amounts.Therefore,in this dissertation,a series of drug delivery systems were prepared with glutamic acid as the main raw material,and used to treat cancer and dissolve thrombus.The main research contents and results are as follows:1.Nanoparticles of nattokinase-second generation polyglutamic acid dendrimer?NK-G₂-RGD?with thrombus targeting ability were prepared.The nanoparticles had high activity of NK.A large number of G₂ were bonded in the peripheral of NK through amide bonds to protect the activity of NK,making it more stable under different temperature and pH conditions.TEM images showed that the nanoparticles had obvious core-shell structure,with NK as the nucleus and G₂ as the shell.In vitro cytotoxicity tests showed that the NK-G₂-RGD had good biocompatibility.The results of in vivo and in vitro thrombolytic experiments showed that the nanoparticles had good thrombolytic effect compared with free NK.2.A double drugs loaded nano polymer conjugate Dox-?NK-G₂?_n based on disulfide cross-linked low-generation peptide dendrimers was developed for combined treatment of colon cancer and its thrombotic complications.The polymer conjugate had high stability,and enzyme activity experiments showed that it can improve the activity of NK.In vitro drug release tests showed that the Dox-?NK-G₂?_n had slow-release effect on NK and GSH-responsive release effect on DOX,and can release Dox rapidly in the solution of 10 mM GSH.The cytotoxic tests showed that?NK-G₂?_n had good biocompatibility.In vitro cell tests and thrombolysis determination showed that Dox-?NK-G₂?_n had the potential of combined treatment of colon cancer and its thrombotic complications.3.A pH-responsive,magnetic and folic acid?FA?targeted drug delivery system?NK-G₂?_n/Dox-FA was prepared with imine bonds as acid responsive chemical bonds.VSM indicated that?NK-G₂?_n had excellent magnetic properties.TEM results showed the cross-linking structure of the conjugates.Enzyme activity measurements and NK release experiments in vitro proved that the polymer can improve the enzyme activity of NK,and had slow-release behavior.Cell experiments showed that?NK-G₂?_n/Dox-FA had H⁺response,which can not only be decomposed in the weak acid environment of tumor tissues and release Dox-FA,but also easily ingestion by cancer cells that improved the anti-tumor effect of anti-cancer drug Dox.The thrombolytic experiment showed that?NK-G₂?_n had good thrombolytic effect.