title: Synthesis and in vitro evaluation of novel star-shaped block copolymers (blocked star vectors) for efficient gene delivery.
abstract: Novel 4-branched diblock copolymers consisting of cationic chains as an inner domain and nonionic chains as an outer domain were prepared by iniferter-based living radial polymerization and evaluated as a polymeric transfectant. The cationic polymerization of 3-(N,N-dimethylamino)propyl acrylamide (DMAPAAm) using 1,2,4,5-tetrakis( N,N-diethyldithiocarbamylmethyl)benzene as a 4-functional iniferter followed by the nonionic block polymerization of N,N-dimethylacrylamide (DMAAm) afforded 4-branched diblock copolymers with controlled compositions. By changing the solution or irradiation conditions, 4-branched PDMAPAAms with molecular weights of 10,000, 20,000, and 50,000 were synthesized. In addition, by graft polymerization, PDMAPAAm-PDMAAm blocked copolymers with copolymer composition (unit ratio of DMAAm/DMAPAAm) ranging from 0.18 to 1.0 for each cationic polymer were synthesized. All polymers were shown to interact with and condense plasmid DNA to yield polymer/DNA complexes (polyplexes). A transfection study on COS-1 cells showed that the polyplexes from block copolymers with cationic chain length of approximately 50,000 and a nonionic chain length of 30,000, which were approximately 200 nm in diameter and very stable in aqueous media, had the most efficient luciferase activity with minimal cellular cytotoxicity under a charge ratio of 20 (vector/pDNA). The PDMAPAAm-PDMAAm-blocked, star-shaped polymers are an attractive novel class of nonviral gene delivery systems.
authors.affiliation: Department of Bioengineering, Advanced Medical Engineering Center National Cardiovascular Center Research Institute, Suita, Osaka, Japan. nakayama@ri.ncvc.go.jp
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kakei
authors.forename: Ayaka
authors.initials: A
authors.lastname: Ishikawa
authors.forename: Yue-Min
authors.initials: YM
authors.lastname: Zhou
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Kingo
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000818:Animals; D019556:COS Cells; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D008970:Molecular Weight; D010957:Plasmids / Q000235:genetics; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity; D014162:Transfection / Q000379:methods*
chemical_list: D000178:Acrylamides; C493602:N,N-dimethylaminopropylacrylamide; D011108:Polymers; C099046:N,N-dimethylacrylamide