Preparation Of Targeted Nanoprodrugs Based On Carbohydrate Ligands And Preliminary Research On Anti-tumor

Traditional chemotherapy drugs will not only kill tumor cells but also cause damage to normal cells due to their poor tumor cell specificity,resulting in serious toxic and side effects.Moreover,many chemotherapeutic drugs have low bioavailability due to poor water solubility,which limits their clinical application.Nano delivery system can improve the security and therapeutic effect of currently used chemotherapeutic drugs.However,there are still some disadvantages,such as low drug loadings（usually less than 10%）,poor stability,damage for normal tissues and cells,particularly in the liver and kidney due to the accumulation of nanocarriers in degradation and metabolism.Therefore,modification of chemotherapeutic drugs or nanocarriers will have the capacities of active tumor targeting and low toxicity,which will be an effective strategy to improve anti-tumor activity.The modification of sugar ligand not only can greatly improve the water solubility of drugs and the hydrophilicity of nanocarriers,but also achieve active tumor targeting through glucose transporter（GLUT）and glycosidase.In this study,we developed self-assembly targeted nanosupramolecular prodrug camptothecin-glycoligand（CPT-GL）and maltose-PEG-azobenzene（Malt-PEG-ABZ）nanomicelle delivery system based on sugar ligand for tumor treatment through glycoligand modification of antitumor drugs.The specific contents are shown below:In chapter 2,glutathione（GSH）sensitive self-assembled nanosupramolecular prodrug CPT-GL is designed and developed.Glucose,maltose and maltotriose with similar structure and different molecular weight are linked to CPT through disulfide bond.CPT-SS-Glucose,CPT-SS-Maltose and CPT-SS-Maltotriose are obtained,which not only greatly increases the solubility of CPT,but also has the capacities of active tumor targeting and GSH response etc.CPT-GL has few steps in synthesis and high yield.The structure and purity of intermediates and final compounds are proved by MS,NMR and HPLC.GSH sensitivity assay demonstrates that CPT-GL can respond to the high expression of GSH in tumor microenvironment.The disulfide bond is broken,and highly toxic CPT is released.Solubility experiments have confirmed that CPT-SS-Maltose has the best solubility and is superior to irinotecan（IR）.The calculated drug loadings of CPT-GL are 41.3%,34.6%and 29.8%,respectively.Particle size,zeta potential,transmission electron microscope（TEM）and critical micelle concentration（CMC）experiments prove that CPT-GL can assembled into filamentous nanostructures in water.In cell experiments,cellular uptake of CPT-GL is significantly higher than that of CPT and IR,and cytotoxicity is lower than that of CPT.Cell experiments are very convenient without requiring any dyes because CPT has strong UV absorbance and fluorescence intensity which can be detected by flow cytometry and confocal microscopy.In vivo imaging experiments have proved that CPT-GL can increase the concentration of drugs in the brain through the blood-brain barrier and achieve brain-targeted drug delivery,which is applied in the treatment of brain-related tumors.In chapter 3,on the basis of the research in chapter 2,nanomicelle modified by maltose is synthesized and encapsulated GPX4 active inhibitor RSL3 to form Malt-PEG-Abz@RSL3 nanomicelle.The structure and purity of Malt-PEG-Abz are confirmed by MS and NMR.Hypoxia experiments demonstrate the hypoxic response of azobenzene structures.Particle size,zeta potential,TEM experiments prove the stability of Malt-PEG-Abz@RSL3.Cell experiments show that Malt-PEG-Abz@RSL3 release RSL3 and inhibit GPX4 activity in tumor cells.Meanwhile,a key coenzyme NADPH participated in synthesis of GSH and Trx（SH）2 is depleted by azobenzene moiety,resulting in decreasing GSH and Trx（SH）2,which dually induce ferroptosis in tumor cells and promote cell apoptosis.