title: Influence of RNA Strand Rigidity on Polyion Complex Formation with Block Catiomers.
abstract: Polyion complexes (b-PICs) are prepared by mixing single- or double-stranded oligo RNA (aniomer) with poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) (block catiomer) to clarify the effect of aniomer chain rigidity on association behaviors at varying concentrations. Here, a 21-mer single-stranded RNA (ssRNA) (persistence length: 1.0 nm) and a 21-mer double-stranded RNA (small interfering RNA, siRNA) (persistence length: 62 nm) are compared. Both oligo RNAs form a minimal charge-neutralized ionomer pair with a single PEG-PLL chain, termed unit b-PIC (uPIC), at low concentrations (<≈ 0.01 mg mL(-1)). Above the critical association concentration (≈ 0.01 mg mL(-1)), ssRNA b-PICs form secondary associates, PIC micelles, with sizes up to 30-70 nm, while no such multimolecular assembly is observed for siRNA b-PICs. The entropy gain associated with the formation of a segregated PIC phase in the multimolecular PIC micelles may not be large enough for rigid siRNA strands to compensate with appreciably high steric repulsion derived from PEG chains. Chain rigidity appears to be a critical parameter in polyion complex association.
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Chaya
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Shigeto
authors.initials: S
authors.lastname: Fukushima
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Sumiyo
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.|Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Takemoto
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.|Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Osada
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.|Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan.|Innovation Center of NanoMedicine, Institute of Industry Promotion-Kawasaki, 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki, 210-0821, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.|Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.|Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.|Innovation Center of NanoMedicine, Institute of Industry Promotion-Kawasaki, 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki, 210-0821, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D019277:Entropy; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000031:analogs & derivatives* / Q000737:chemistry; D008823:Micelles; D011092:Polyethylene Glycols / Q000737:chemistry*; D012330:RNA, Double-Stranded / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D008823:Micelles; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; C092361:poly(ethylene glycol) lysine copolymer; D011092:Polyethylene Glycols; D008239:Lysine
keywords: block copolymers; micellization; polyion complexes; siRNA; supramolecular chemistry