title: Rod-to-Globule Transition of pDNA/PEG-Poly(l-Lysine) Polyplex Micelles Induced by a Collapsed Balance Between DNA Rigidity and PEG Crowdedness.
abstract: The role of poly(ethylene-glycol) (PEG) in rod-shaped polyplex micelle structures, having a characteristic core of folded plasmid DNA (pDNA) and a shell of tethered PEG chains, is investigated using PEG-detachable polyplex micelles. Rod shapes undergo change to compacted globule shapes by removal of PEG from polyplex micelles prepared from block copolymer with acid-labile linkage between PEG and poly(l-lysine) (PLys) through exposure to acidic milieu. This structural change supports the previous investigation on the rod shapes that PEG shell prevents the DNA structure from being globule shaped as the most favored structure in minimizing surface area. Noteworthy, despite the PEG is continuously depleted, the structural change does not occur in gradual shortening manner but the rod shapes keep their length unchanged and abruptly transform into globule shapes. Analysis of PEG density reveals the transition occurred when tethered PEG of rod shapes has decreased to a critical crowdedness, i.e., discontacted with neighboring PEG, which eventually illuminates another contribution, rigidity of DNA packaged as bundle in the rod shapes, in addition to the steric repulsion of PEG, in sustaining rod shapes. This investigation affirms significant role of PEG and also DNA rigidity as bundle in the formation of rod-shaped structures enduring the quest of compaction of charge-neutralized DNA in the polyplex micelles.
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Theofilus A
authors.initials: TA
authors.lastname: Tockary
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, 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: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Motoda
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Hiki
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Qixian
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Kaori M
authors.initials: KM
authors.lastname: Takeda
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Anjaneyulu
authors.initials: A
authors.lastname: Dirisala
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Shigehito
authors.initials: S
authors.lastname: Osawa
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.|Department of Bioengineering, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.|Division of Clinical Biotechnology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyoku, Tokyo, 113-8656, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D004247:DNA / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D010957:Plasmids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*
chemical_list: D008823:Micelles; D011107:Polylysine; D011092:Polyethylene Glycols; D004247:DNA
keywords: DNA packaging; gene delivery; nanorods; polymers; polyplex micelles, micelles