Preparation Of Multifunctional Carbohydrate-based Nanomaterials And Its Application In Cancer Targeted Therapy

Developing effective methods for the diagnosis and treatment of breast cancer and liver cancer is an urgent problem for clinical medical researchers.With the rapid development of nano science and technology as well as the remarkable achievements made in biomedical field,nano-system provides new strategies and hopes for the diagnosis and treatment of cancer.Carbohydrates is an important biological macromolecules.The study of their structure and function is very important for the understanding of the biological basis,and studies on carbohydrates have provided new major disease diagnosis and treatment strategies.This dissertation focuses on the research of multi-functional carbohydrate-based nanomaterials system,which has many functions such as targeting,acid sensitivity,imaging,drug loading and nucleic acid.The specific research contents are as follows:?1?The experimental study of mannose-modified amphiphilic cyclodextrin nanosystems for targeted breast cancer therapyWe successfully constructed a mannose-modified amphiphilic cyclodextrin nanosystem loaded with the anticancer drug doxorubicin.The primary hydroxyl surface of the cyclodextrin has been modified with hydrophilic targeting ligand mannose molecule,and the secondary hydroxyl surface is modified with different lengths of the alkyl chains.After drug loading,the amphiphilic cyclodextrin can be self-assembled to form micelles with size of 199.4±2.8 nm.The drug loading capacity is 12.3±0.94%and drug encapsulation efficiency is 59.3±5.55%.The nano drug delivery system exhibits acid-sensitive release characteristics and remains stable under normal physiological conditions.The MDA-MB-231 breast cancer cells overexpressing the mannose receptor on the cell surface are used as the test cells,and the normal epithelial HEK293 cells are the control cells.Confocal scanning laser microscope experiment,flow cytometry and cytotoxicity experiments were performed to prove that the drug-loaded nanosystem can be specifically endocytosed by MDA-MB-231 cells and has a significant growth inhibition effect on the cells.The animal model experiments of solid tumors showed that the modification of mannose enabled the drug-loaded nanosystems to be highly selective,making the drug-loaded nanosystems have a good growth inhibitory effect on cancer tissues,and its growth inhibition rate for cancer tissues was 65%,which is much higher than 43%accquied by the free anticancer drugs.And the tissue section experiments showed that the drug-loaded nanosystems have low toxicity to various major organs.The experimental results show that the mannose-modified amphiphilic cyclodextrin-loaded nanosystem has high-efficiency targeting ability,improves the efficacy of anticancer drugs and reduces toxic side effects.?2?Experimental study of galactose-modified multifunctional nano-system for targeted liver cancer in combination of chemotherapy and gene therapyWe have successfully established a multi-functional polymer nano-system with multi-functional polymer nano-systems,such as targeting,tracing,acid-sensitive,and simultaneous loading of drugs and nucleic acids,for the experimental study of targeting liver cancer for combination of chemotherapy and gene therapy.Fluorescent rhodamine B has been modified into a bromine-containing macroinitiator,which triggers the monomeric N,N-dimethylaminoethyl methacrylate?DMAEMA?and 3-azido-2-hydroxyl polymerization of propyl methacrylate?GMA-N₃?to form a copolymer.This polymer was then reacted with galactose containing alkynyl groups with click chemistry to obtain the target copolymer.The target copolymer forms a nano-system with size of 153.8±4.5 nm by self-assembly.The drug loading capacity is 12.6±0.03%and drug encapsulation efficiency is 58.0±3.4%.The nanomicelles loaded with nucleic acids and drugs have good stability in high-glucose medium containing 10%fetal bovine serum and can trigger drug release under acidic pH conditions.Targeted delivery of doxorubicin and gene transfection were realized in HepG2 and Huh7 cells.And the determination of protein levels and mRNA levels,as well as cytotoxicity experiments have demonstrated that the nano-system has a good synergistic effect of nucleic acids/drug treatment.In addition,the synergistic effect of chemotherapy and gene therapy of the nano-system was performed in subcutaneous and orthotopic liver cancer mouse models,which shows with 84%.It is higher than the sum of the efficiencies of chemotherapy or gene therapy alone,reflecting a good synergistic effect.?3?Experimental study of cercosporin loaded galactose-modified multi-functional nano-system for targeted photodynamic therapy of liver cancerWe successfully encapsulated the perylenequinones photosensitizing compound cercosporin into a galactose-modified multifunctional polymer nano-system to form a photosensitizer composite nanomaterial with a particle size of 103±9.9 nm.The extracellular and intracellular experiments demonstrated that the cercosporin loaded nanomaterials have good targeting ability,can specifically recognize liver cancer cells and endocytosed by liver cancer cells through galactose-asialoglycoprotein receptor interaction.And it can trigger the release of cercosporin under acidic pH conditions,which reached an accumulative release amount of 97%after 48 h,and generated a large amount of singlet oxygen?the singlet oxygen yield was calculated to be 0.87?under the light of 463 nm wavelength to exert the photodynamic therapy efficiency.While in normal cells and physiological environment,the cercosporin was stably encapsulated in the nano-system.The survival rate of the cells was higher than 80%even when the cells were incubated with HepG2 and HEK293 cells at a concentration of 1?g·mL^-1for 24 h,which shows the low toxicity of the cercosporin loaded nano-system.However,under the exposure of the cercosporin excitation wavelength,the cercosporin loaded nano-system exhibits enhanced cytotoxicity towords HepG2,which shows targeted photodynamic interference in specific cancer cell growth.