Construction And Anticancer Study Of Drug Delivery Systems Based On Host-guest Interaction Of Cyclodextrin

Background:For the past decades,more and more polymeric nanomaterials have been explored in the diagnosis and treatment of tumors.Nanoparticles-based drug delivery systems exhibt the advantages in extention of the retention time in the body,increase of drug aggreagation in the tumor tissue,reduction of the side effects and so on.With the intensive development of understanding in the physiology and pathology characteristics of tumors,the researchers recognise that it is urgent demanded to impart the nanoparticles-based drug delivery system multifuntions to bypass the multiple barriers in-vivo.However,the functionalization of nanoparticles largely relies on the complicated chemical reactions,and is drastically confined by the nature of the polymers to obtain an inflexible structure.To address this issue,the drug delivery systems based on supramolecular interaction attract tremendous interest.The supramolecular chemistry is fundamentally different from the traditional covalent chemistry,which mainly depend upon hydrogen bond interaction,?-? bond interaction,van der Waals force,electrostatic interaction and so on.The interaction of this supramolecule is generally accomplished by recognizing the specific molecules in mild condition and reversible way.The most impressive advantage of drug delivery systems based on supramolecular chemistry is a modularized assembly manner for ease of introduction of diverse targeting groups and environmental responsive groups.In this thesis,the intelligent drug delivery systems based on supramolecules were constructed by the interaction of cyclodextrin and PEG,and their anti-tumor biological effects were studied in vitro.My research content is divided into the following two parts:Part one:Preparation of paclitaxel nanocrystal hybrid hydrogel andits effect on drug resistance researchObjective:To delivery hydrophobic antitumor drugs and overcome the multidrug resistance of tumor cells,we reported a novel strategy of drug delivery system.Methods:Firstly,D-?-Tocopherol polyethylene glycol 1000 succinate(TPGS)was used to emulsify the PTX to prepare the drug nanocrystals.And then an injectable hydrogel was formed by using the drug nanocrystals and ?-cyclodextrin through the supramolecular interactions.The physiochemical properties of the hydrogels were investigated by XRD,TEM and SEM.As the major mechanism of drug resistance,the suppression of Pgp pump was evaluated.To explore the anti-tumor biological effect of drug-loaded supramolecular hydrogel,the cell viability test and cell apoptosis test were carried out by using paclitaxel sensitive cell line A549 and paclitaxel resistant cell line A549/T.Results:The results of dynamic light scattering and transmission electron microscopy showed that paclitaxel nanocrystals were successfully prepared.The drug release test in vivo results showed that the drug delivery system could release the drug antitumor drugs quickly.In the cytotoxicity test and the apoptosis experiment,the hydrogel can effectively inhibit the paclitaxel-resistant cells,compared with the control group,there is a significant difference.Conclusion:Paclitaxel nanocrystals and ?-cyclodextrins(?-CD)successfully self-assemble to form supramolecular hydrogels that deliver both hydrophobic antitumor drugs(PTX)and bio-macromolecular drugs(TPGS),and the hydrogels could overcome the tumor drug resistance.Part two:A facile strategy to engineer a nanoassembly Nanoparticle and the drug delivery researchObjective:we provided a simple and versatile template strategy to co-delivery of multiple drugs with tunable drug loading content with tumor-acidity triggered targetability to combat drug resistance.Methods:First,PTX nanocrystals were prepared by using TPGS as the emulsifier.TPGS was not merely worked as an emulsifying agent but also a macromolecular drug capable of interrupting the P-gp pump.The crosslinked clusters of PTX nanocrystals were engineered to function as core of the nanoparticles to provide ultrahigh drug loading efficiency,which were crosslinked with poly(?-cyclodextrin)(PCD)as soft templates,such as poly(isobutylene-alt-maleic anhydride)-graft-p-cyclodextrin or hyaluronic acid-graft-?-cyclodextrin and etc.A acid-labile prodrug,poly(ethylene glycol)-doxorubicin(mPEG-DOX)was adopted as the shell which connected the core via supramolecular interactions between ?-CD and doxorubicin.The nanoparticles were characterized by dynamic light scattering,transmission electron microscopy and infrared spectroscopy.Cytotoxicity assay was used to detect the ability of nanoparticles to inhibit tumor cells.The endocytosis and intracellular distribution of nanoparticles were observed under confocal laser scanning microscopy.Quantitative analysis of intracellular mean fluorescence intensity was performed by flow cytometry.In addition,nanoparticles with oligonuclear hyaluronic acid modified?-cyclodextrin(HA-CD)as a template were constructed and the nanoparticles have the ability targeting to the cells expressing CD44+receptors.And the biological antitumor effect was evaluated by human hepatoma cell line HepG2.Results:The results of dynamic light scattering show that the average particle size of nanoparticles is 190±15nm and PDI is 0.175,and the nanoparticles have good stability in buffer.In acidic solution,Hydrazone bond between adriamycin and mPEG-hydrazide breaks,and the nanoparticles are dissociated from the shell.TEM results show that the cross-linked clusters of paclitaxel nanocrystals are the nuclei of nanoparticles,which can greatly increase the drug loading rate of nanoparticles.The cytotoxicity of MCF-7/ADR cell line showed that the nanoparticles had better cytostatic effect than doxorubicin and paclitaxel,which indicated that the nanoparticles could overcome the drug resistance.Laser confocal experimental results and flow cytometry results show that nanoparticles can successfully deliver a variety of different antineoplastic drugs into the cells.Biological experiment of HepG2 cells with hyaluronic acid modified nanoparticles showed that the nanoparticles were able to targetly delivery antitumor drugs to CD44+receptors cells and effectively inhibit tumor cells.Conclusion:Biocompatible nano-particles with core-shell structures fabricated by self-assembly from mPEG-DOX,p-CD,PTX and TPGS were utilized as vecteurs for targeted co-transport of DOX and PTX in the anti-tumor therapies.and targeted group could be used for co-delivery by this type of NPs.