Construction Of Nanometer Drug-carrying System Loaded With Ursolic Acid And Its Tumor Activity In Vitro

At present,the clinical treatment of cancer mainly depends on anti-cancer drugs,and the anti-cancer drugs developed from natural products are about one-third of the total anti-cancer drugs.There are many types of natural anticancer drugs in nature and abundant resources,but natural anticancer drugs have their own shortcomings,such as poor water solubility,poor targeting,and low bioavailability,which greatly limits their clinical application..Therefore,the combination of natural anticancer drugs and new nanomaterials to build a targeted nano drug delivery system can significantly improve the water solubility and bioavailability of natural anticancer drugs,and give natural anticancer drugs targeting,which is conducive to drug concentration Enrichment in cancerous areas reduces damage to normal tissues.Nanomaterials can also passively target cancerous tissues by virtue of their own EPR effect,further enhancing the targeting of drugs.The new nanomaterial quantum dot synthesis method is simple,and has excellent fluorescence performance and very low biological toxicity.Therefore,it can be used in nano-drug-loaded fluorescence imaging research and realize the fluorescence imaging function of drugs in cells,which is intuitive,fast and accurate To obtain important information such as the distribution,release and pharmacodynamic mechanism of nano-drugs in cells to provide an experimental basis for the design and development of clinical nano-drugs.According to reports,triterpenoids and their derivatives have many pharmacological activities,such as anti-tumor,anti-inflammatory,anti-AIDS HIV protease and so on.Ursolic acid(UA)is a common pentacyclic triterpenoid compound and has pharmacological properties such as antibacterial,anti-inflammatory,anti-viral,and anti-tumor.It has strong inhibitory activity on a variety of tumor cells.Research on ursolic acid as a cancer prevention and treatment drug.Ursolic acid has good anti-tumor activity,the mechanism is that it can block the cell cycle progression of G1 phase and induce apoptosis.Although ursolic acid can significantly inhibit the proliferation of tumor cells,its poor water solubility and extremelylow bioavailability limit its clinical application.Based on this,two ursolic acid-targeted fluorescent drug delivery systems were constructed,and the two systems were characterized in detail to evaluate their anti-cancer activity in vitro.The specific research content is divided into the following two parts:1.In this paper,Zn O QDs were successfully synthesized by sol-gel method and the surface of quantum dots was rich in amino functional groups.The Zn O QDs synthesized by this method not only have excellent fluorescence properties and good water solubility,but also have p H sensitivity.Co-precipitation method was used to prepare magnetic Fe3O4 nanoparticles.After being adsorbed by oleic acid molecules and oxidized by KMn O4,the nanoparticles were enriched in the surface with carboxyl functional groups.Subsequently,the two nanomaterials were characterized in detail by a series of means such as TEM,SEM,FTIR,UV,XRD and so on.Zn O QDs and Fe3O4 nanoparticles are chemically coupled to construct magnetic composite nanoparticles with fluorescent properties(Fe3O4@Zn O),and the surface of the composite nanoparticles is loaded with the natural anticancer drug ursolic acid to establish a p H-responsive magnetic target Nanometer drug loading system(Fe3O4@Zn O-UA).The inhibitory effect of ursolic acid and nano drug-carrying system on tumor cells was detected by MTT method,and the ursolic acid and nano drug-carrying system were applied to Hep G2,SMMC-7721,MCF-7 and A549 tumor cells respectively.The results showed that The inhibitory activity of the nano drug-carrying system on tumor cells is superior to ursolic acid used alone.Cell uptake experiments proved that the nano drug-carrying system can cross the cell membrane and enter the cytoplasm,showing bright yellow fluorescence under a fluorescent microscope,successfully achieving the cell imaging function,and providing a basis for further research on the mechanism of action of the nano drug-carrying system.Finally,a series of tests were carried out on the nano drug-loading system through a fluorescence microscope and a high-content imaging system,and it was found that the nano drug-loading system can cause the mitochondrial membrane potential to decrease,and the reactive oxygen species(ROS)to increase,which promotes tumor cell apoptosis.2.In this paper,Zn-CQDs were prepared by high-temperature pyrolysis.The quantumdots have excellent fluorescence properties.The morphological characterization of Zn-CQDs by TEM shows that the particle size of quantum dots is 5.16 ± 0.32 nm.The natural anticancer drug ursolic acid is modified with polyethylene glycol and folic acid,not only to improve water solubility and to make it targeted;to further enhance anticancer activity,it is connected to the natural anticancer drug paclitaxel(PTX),The formation of UA-PEG-FA-PTX helps to prolong the residence time in the body.The Zn-CQDs were physically adsorbed with UA-PEG-FA-PTX by electrostatic force,and the nano-drug loading system Zn-CQDs@UA-PEG-FA-PTX with fluorescent properties was constructed.The drug-carrying system was characterized in detail by TEM,SEM,FTIR,UV,XRD,1H NMR and other instruments.The inhibitory activity of nano-drug system Zn-CQDs@UA-PEG-FA-PTX on tumor cells was detected by MTT method.The results showed that the inhibitory activity of nano-drug system on tumor cells was superior to ursolic acid alone.Cell uptake experiments prove that the nano drug-loading system can enter the cytoplasm and realize the function of cell imaging.Finally,a fluorescence microscope and a high-content imaging system were used to conduct apoptosis-related experiments on the nano-drug-loaded system.It was found that the nano-drug-loaded system could induce apoptosis,meanwhile,the mitochondrial membrane potential decreased and the reactive oxygen species increased.