title: Linear polyethyleneimine grafted to a hyperbranched poly(ethylene glycol)-like core: a copolymer for gene delivery.
abstract: A block copolymer of a hyperbranched poly(ethylene glycol)-like core and linear polyethylenimine (HBP) was synthesized by a facile synthetic route that included (1) a single-step cationic copolymerization of diepoxy and polyhydroxyl monomers, (2) derivatization of hydroxyl groups of the core HBPEG copolymer with either tosyl or chloromethylbenzoyl chlorides resulting in a corresponding macroinitiator, and (3) synthesis of HBPEG-block-poly(alkyl oxazolines). HBPEG-block-linear polyethyleneimine (HBP) was obtained by hydrolysis of HBPEG-block-poly(alkyl oxazolines). Linear PEI-bearing hyperbranched polycations (HBP) had lower inherent toxicity in cell culture than PEG-grafted linear polyethyleneimines (PEGLPEI). PEGLPEI formed a complex with DNA with an average diameter of 250 nm. The complexes were loosely condensed and formed aggregates and precipitates during storage. By contrast, hyperbranched polycations (HBP) formed approximately 50 nm nanocomplexes with DNA that were stable for several weeks and showed resistance to DNAse I-mediated degradation. The 'inverted' block copolymers showed several orders of magnitude higher transfection efficiency than PEGLPEI in vitro. Because of the biocompatibility and higher transfection efficiency, the 'inverted' block copolymer merits further investigation as a gene carrier.
authors.affiliation: Center for Molecular Imaging Research, Massachusetts General Hospital, Building 149, 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Pallab
authors.initials: P
authors.lastname: Banerjee
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Alexei
authors.initials: A
authors.lastname: Bogdanov
mesh_terms: D000818:Animals; D019556:COS Cells; D016923:Cell Death / Q000187:drug effects; D002522:Chlorocebus aethiops; D004247:DNA / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D023282:Nuclease Protection Assays; D010957:Plasmids / Q000235:genetics; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry*; D011094:Polyethyleneimine / Q000008:administration & dosage / Q000737:chemistry*; D011108:Polymers / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry; D014162:Transfection / Q000379:methods*
chemical_list: D011108:Polymers; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D004247:DNA; D003850:Deoxyribonuclease I