The Preparation And Biological Research Of Glycosylated Polymer Conjugate Drugs For Liver Target

As the energy carrier and important biological information molecules, sugar plays a crucial role in many important physiological processes, and also controls the transmission of biological information through their specific recognition with the protein. It has been found that the lactose (galactose) has specific recognition and binding characteristic with lactose (galactose) receptor that exists on the surface of mammalian liver cells. By virtue of this property, drug delivery carriers containing lactose (galactose) to achieve active targeting have received more and more attention.Aliphatic polyester (such as polylactide), one of the most important biodegradable materials in biomedical application, has been widely used in carriers in drug delivery, sutures and temporary matrixes or scaffolds in tissue engineering due to its biodegradability, good biocompatibility, high mechanical properties and excellent shaping and molding properties. However, the following factors limit its applications: 1) their lack of adequate interactions with cells, leading to unexpected foreign body reactions in vivo; 2) the difficulty in their modification because they do not contain any reactive groups; 3) their low hydrophilicity. In this thesis, we attempt to improve the hydrophilicity and biocompatibility of polylactide by introducing poly(ethylene glycol), a molecule that is hydrophilic, nontoxic, biocompatible and nonimmunogenic. By introducing aliphatic carbonate monomers, the biocompatibility, physicochemical properties and biodegradability can be adjusted. What's more, with this method many kinds of reactive groups can be introduced into the polymer for futher conjugation with drug and sugar molecules. Targeted nano-micelles were prepared by self-assembling these amphiphilic polymers. Their applications were investigated. Detailed studies are as follows:1. A novel block copolymer PLLA-PLC carrying pendant thiol groups was designed and synthesized. The lactose molecules were introduced into the hydrophilic segment (PLC) of the polymer, obtaining PLLA-PLC/Lactose. The polymers were characterized by 1H NMR and FT-IR. Contact angle results proved the improved hydrophilicity by lactose grafting; in vitro cell culture verified their good biocompatibility; laser scanning confocal microscope (CLSM) and surface plasmon resonance (SPR) technology demonstrated specific recognition and binding effect between lactose-containing polymer and ricin agglutinin (RCA). Environmental Scanning electron microscopy (ESEM), dynamic light scattering (DLS), and fluorescence spectroscopy were used to characterize the morphology, particle size and distribution, critical micelle concentration of the sugar-containing polymer micelles, respectively.2. Lactose was azidized and alkynyl containing amphiphilic block copolymer PEG-PMPC-PLA was prepared. Then lactose was introduced into the hydrophobic segment of PEG-PMPC-PLA via Cu(I) catalyzed alkynyl-azide cycloaddition reaction (click chemistry). In vitro cell culture verified their good biocompatibility. Hydroxyl carrying copolymer PEG-b-P(LA-co-DHP) was synthesized. The anticancer drug doxorubicin was conjugated to the P(LA-co-DHP) segment, obtaining PEG-P(LA-DHP/Dox). Mutifunctional micelles were prepared by co-assembling method. ESEM, DLS characterized the morphology, particle size and distribution of the nano-micelles. Laser confocal microscope confirmed lactose receptor-mediated endocytosis. MTT method indicated the cytotoxicity of Dox-conjugated micelles.3. On the one hand, block copolymers with lactose conjugated at the segment PEG, lactose-PEG-PLLA, was prepared. Its specific binding effect with RCA was demonstrated. On the other hand Rhodamine B labeled block copolymer was synthesized. Mutifunctionalized micelles were prepared by co-assembling the two copolymers. ESEM, DLS and fluorescence spectroscopy characterized the morphology, particle size and distribution of the nano-micelles. Laser confocal microscope confirmed lactose receptor-mediated endocytosis. The micelles were injected into mice via tail vein injection. At specific time intervals, the mice were sacrificed and the in vivo distribution of the micelles solution was investigated by CRI in vivo imaging systems and laser scanning confocal microscope. The results showed obvious liver targeting effect.4. The in vivo anti-tumor activity of lactose targeting, drug conjugated micelles PEG-P(LA-DHP/Dox) was investigated, including tumor diameter, body weight change and life cycle variation after drug administration.