| Cyclodextrins (CDs) are a series of natural cyclic oligosaccharides composed of α-1,4-coupled D-glucose units. The most commonly used CD subtypes are α-CD, β-CD andγ-CD, which consist of6,7,8D-glucose units, respectively. CDs display a bucket-likestructure with a hydrophobic inner cavity that can form inclusion complexes with variousguest molecules, including many kinds of polymers. Meanwhile, abundant hydroxylslocated on the hydrophilic exterior of CDs show varied reactivity, which make it easy tosynthesize modified CDs. CDs have often been used to design and construct polymericmaterials by host-guest interactions or covalent modifications. CD-based polymericmaterials usually exhibit unique characteristics in terms of mechanical properties,stimuli-responsiveness, good availability, etc., facilitating their wide applications in drugdelivery, gene transfection, food additives, flavoring materials and cosmetics.In this dissertation, we designed and constructed several CD-based polymericsystems through host-guest interaction or by Michael addition reaction. The chemicalstructures and properties of these systems were thoroughly characterized, and theapplications in drug and gene delivery of these systems were also estimated. The detailsand key conclusions are described as follows: 1. Construction of interpolymer complexes with controlling particle size throughhost-guest interaction for drug deliveryA new method to adjust the particle size of interpolymer complexes was developedby introduction of host-guest interaction into the dilute aqueous solution of poly(acrylicacid)(PAA) and poly(ethylene glycol)(PEG). Due to the cooperative hydrogen-bondinginteraction, PAA formed the interpolymer complexes with PEG. Adding β-CD into dilutePAA/PEG aqueous solution, the competition between host-guest and hydrogen-bondinginteractions happened. The β-CD/PAA/PEG ternary systems were well characterized byultraviolet-visible absorption spectroscopy (UV-Vis), dynamic light scattering (DLS),transmission electron microscopy (TEM), diffusion NMR spectroscopy, Fourier transforminfrared (FTIR) and solid-state13C NMR spectroscopy. The results indicated that thehydrophobic cavity of β-CD was threaded by linear polymers so that the hydrophilicity ofPAA/PEG interpolymer complexes was improved greatly. Adjusting the amounts of β-CD,the particle size of the interpolymer complexes could be readily controlled. The lowcytotoxicity of various β-CD/PAA/PEG ternary complexes was confirmed using the MTTassay in COS-7cell line. Doxorubicin (DOX), an anticancer drug, was encapsulated intothe β-CD/PAA/PEG ternary complexes. The DOX-loaded β-CD/PAA/PEG ternarycomplexes had been analyzed by flow cytometry (FCM) analysis, confocal laser scanningmicroscopy (CLSM) and the methyl tetrazolium (MTT) assay against human cervicalcarcinoma cell (Hela). The results indicated that β-CD/PAA/PEG ternary complexes withcontrolled particle size could be used as safe and promising drug carriers.2. Preparation and characterization of supramolecular hydrogel consisting of adendritic multiarm copolymer brush and α-CDs for drug deliveryThrough reversible addition-fragmentation transfer (RAFT) polymerization ofpoly(ethylene glyco1) methyl ether methacrylate (PEGMA) initiated by dendritic macroinitiator, a dendritic multiarm copolymer brush was successfully synthesized.Benefiting from the cooperation of host-guest interaction and hydrogen-bondinginteraction, a supramolecular hydrogel formed between the dendritic multiarm copolymerbrush and α-CDs in an aqueous solution. The resultant hydrogel showed uniquetemperature-dependent sol-gel phase transition. The structure and the forming mechanismof the supramolecular hydrogel were characterized by FTIR,NMR and X-ray diffraction(XRD) techniques. MTT assay in NIH-3T3cell line proved the low cytotoxicity of thehydrogel. The anticancer drug DOX could be loaded into the hydrogel, and theencapsulated DOX could be released gradually in a long time. It suggested that thissupramolecular hydrogel consisting of a dendritic multiarm copolymer brush and α-CDscould be useful as an injectable drug delivery system.3. Design and synthesis of hyperbranched poly(amido amine) containing β-CDs as anonviral gene delivery vectorHyperbranched poly(amido amine) containing different amounts of β-CDs(HPAMAM-CDs) were synthesized through a simple and efficient one-step Michaeladdition copolymerization of N, N'-methylenebis(acrylamide)(MBA),1-(2-aminoethyl)piperazine (AP) and mono-6-dexy-6-ethylenediamino-β-CD (EDA-β-CD). NMR, GPC(gel permeation chromatography), and FTIR techniques were used to characterize thestructure of the obtained HPAMAM-CDs. MTT assay proved that the cytotoxicity becamelower as the β-CD content increased. The agarose gel electrophoresis results indicated thatHPAMAM-CDs could condense pDNA very well. In vitro transfection evaluation ofHPAMAM-CD/pDNA complexes in the absence or presence of10%FBS showed highgene transfection efficiencies. Furthermore, the inner cavities of β-CDs inHPAMAM-CDs could be used to encapsulate drugs through host-guest interaction.Therefore, the HPAMAM-CDs may have potential application in the combination of genetherapy and chemotherapy. 4. Fluorescence properties of HPAMAM-CDs and their application as fluorescenttracker in gene transfection processHPAMAM and HPAMAM-CDs were found to display fluorescence with theemission bands of nearly whole visible wavelength range. In comparison to pureHPAMAM, the fluorescence intensity of HPAMAM-CDs was enhanced significantly. Thefluorescence enhancement of HPAMAM-CDs might result from the restricted rotationalmotion of the terminal chains caused by the steric hindrance of big β-CD units, which wasconfirmed by the differential scanning calorimeter (DSC) results. Benefiting from thestrong fluorescence of HPAMAM-CD, the cell internalization studies ofHPAMAM-CD/pDNA complexes were preformed conveniently without fluorescentlabeling. FCM and CLSM results demonstrated that the cellular uptake ofHPAMAM-CD/pDNA complexes was very fast and HPAMAM-CDs mainly located inthe cytoplasm of the cells during the gene transportation process.
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