title: Block versus random amphiphilic copolymers as antibacterial agents.
abstract: We examined the antibacterial and hemolytic activities in a series of amphiphilic block and random copolymers of poly(vinyl ether) derivatives prepared by base-assisting living cationic polymerization. Block and random amphiphilic copolymers with similar monomer compositions showed the same level of activity against  Escherichia coli . However, the block copolymers are much less hemolytic compared to the highly hemolytic random copolymers. These results indicate that the amphiphilic copolymer structure is a key determinant of activity. Furthermore, the block copolymers induced dye leakage from lipid vesicles consisting of  E. coli -type lipids, but not mammalian lipids, while the random copolymers disrupted both types of vesicles. In addition, both copolymers displayed bactericidal and hemolytic activities at concentrations 1 or 2 orders of magnitude lower than their critical (intermolecular) aggregation concentrations (CACs), as determined by light scattering measurements. This suggests that polymer aggregation or macromolecular assembly is not a requisite for the antibacterial activity and selectivity against bacteria over human red blood cells (RBCs). We speculate that different single-chain conformations between the block and random copolymers play an important role in the antibacterial action and underlying antibacterial mechanisms.
authors.affiliation: Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Oda
authors.forename: Shokyoku
authors.initials: S
authors.lastname: Kanaoka
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
authors.forename: Sadahito
authors.initials: S
authors.lastname: Aoshima
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kuroda
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects*; D016650:Fluorescein-5-isothiocyanate / Q000032:analysis; D005456:Fluorescent Dyes / Q000032:analysis; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007928:Lethal Dose 50; D008027:Light; D008856:Microscopy, Fluorescence; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology; D012542:Scattering, Radiation; D013045:Species Specificity; D013501:Surface-Active Agents / Q000737:chemistry* / Q000494:pharmacology; D014753:Vinyl Compounds / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D005456:Fluorescent Dyes; D011108:Polymers; D013501:Surface-Active Agents; D014753:Vinyl Compounds; C100195:vinyl ether; D016650:Fluorescein-5-isothiocyanate