Synthesis and Characterization of PEGylated Brush-type Polycation Modified with Galactosamine

Abstract

Gene therapy has been generally regarded as a promising treatment for numerous hard curable diseases, such as cancer, genetic and infectious diseases. Seeking a safe and efficient vector plays the most challenging role in gene therapy. In the past decades, non-viral polycation has attracted much more attentions as a promising gene vector due to their good biocompatibility, high condensation ability, as well as easily-adjustable and controlled structures. In the present work, a series of galactosamine (Gal)-conjugated brush-type cationic copolymer P(PEGMEMA-co-PEGMA-Gal)-b-PDMAEMA were prepared via a combination of two-step atom transfer radical polymerization (ATRP) technique and polymer reaction. Firstly, random copolymerization of poly(ethylene glycol)methyl ether methacrylate (PEGMEMA) and poly(ethylene glycol) methacrylate (PEGMA) was carried out to yield the copolymer P(PEGMEMA-co-PEGMA), which was further used as a macroinitiator to polymerize 2-(N ,N-dimethylamino)ethyl methacrylate (DMAEMA), producing the cationic copolymer P(PEGMEMA-co-PEGMA)-b-PDMAEMA. Finally, the brush-type copolymer P(PEGMEMA-co-PEGMA-Gal)-bPDMAEMA was obtained by the modification of pendent hydroxyl groups with galactosamine using N,N'-carbonyldiimidazole (CDI) as the coupling agent. PDMAEMA is a well-known pH-sensitive polycation and has been widely applied for non-viral gene delivery, while the brush-type hydrophilic chains provide the carrier with favorable biocompatibility, prolonged blood circulation time, and reduced non-specific adsorption of proteins. PDMAEMA block would be partially protonated to afford some hydrophobic domains and positive charges at neutral condition, which can bind with DNA via electrostatic interaction to form polycation/DNA polyplex. The Gal moiety on the surface made the polyplex easily recognized by asialoglycoprotein receptors (ASGPRs) over-expressing hepatoma cells and internalized via a receptor-mediated endocytosis process. The chemical structures, molecular weights and molecular weight distributions of P(PEGMEMA-co-PEGMA-Gal)-b-PDMAEMA copolymer were characterized by H NMR, FT-IR, and GPC measurements. The DNA binding capacity of this copolymer was investigated by agarose gel electrophoresis and zeta potential measurements, which indicated that DNA migration could be completely retarded when the N/P ratio was higher than 1.5. The DLS DOI: 10.6023/A14030185