| The largest extravascular barrier of tumors is mainly composed of dense extracellular matrix(ECM)and multilayered tumor cells(MLTC).Traditional nanocarriers usually can not effectively overcome the physiological barrier of solid tumors,so that most of the nanocarriers can only distribute around the tumors' blood vessels and rarely reach the inside of tumors.Because nanocarriers cannot effectively cross this barrier and deliver therapeutic drugs to the deep tissues that cancer stem cells may hide,drug resistance and recurrence of tumors are gradual.In this paper,two types of nanocarriers for anticancer drugs were prepared: one was a pH and enzyme-responsive nanocarriers;the other was a polymer micelle nanocarriers.The results are as follows:1.By modifying the chitosan oligosaccharide and cross-linking with poly-N-isopropylacrylamide,a nanocarrier with a gelatin shell was prepared.Using nuclear magnetic resonance,laser confocal,transmission electron microscopy,cell experiments,animal experiments and other characterization,the test results show that the nanocarrier has the advantages of particle size variability,enzyme responsiveness,fixed-point explosiveness,and tumor enrichment;2.A copolymer triblock drug carrier with PCL-PEG-PCL as micelle was synthesized by solution polymerization,and the anticancer drug 7-ethyl-10-hydroxycamptothecin was treated with cystamine dihydrochloride.(SN38)was modified by disulfide bond.The drug was loaded into the micelle by membrane hydration method,and tested by nuclear magnetic,transmission electron microscopy and high performance liquid chromatography.The preparation was successful and the particle size was 40-60 nm.The drug loading is up to 19.67% and the release efficiency is 62%.3.A drug carrier with modified polyglutamic acid as a micelle was prepared by covalent attachment.First,the polyglutamic acid was modified with different amounts of glutamine,and then reacted with the anticancer drug cis dichlorodiamine platin. |
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