title: Smectic phase in suspensions of gapped DNA duplexes.
abstract: Smectic ordering in aqueous solutions of monodisperse stiff double-stranded DNA fragments is known not to occur, despite the fact that these systems exhibit both chiral nematic and columnar mesophases. Here, we show, unambiguously, that a smectic-A type of phase is formed by increasing the DNA's flexibility through the introduction of an unpaired single-stranded DNA spacer in the middle of each duplex. This is unusual for a lyotropic system, where flexibility typically destabilizes the smectic phase. We also report on simulations suggesting that the gapped duplexes (resembling chain-sticks) attain a folded conformation in the smectic layers, and argue that this layer structure, which we designate as smectic-fA phase, is thermodynamically stabilized by both entropic and energetic contributions to the system's free energy. Our results demonstrate that DNA as a building block offers an exquisitely tunable means to engineer a potentially rich assortment of lyotropic liquid crystals.
authors.affiliation: Department of Physics and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Salamonczyk
authors.affiliation: Institute of Complex Systems ICS-3, JARA-SOFT, Forschungszentrum Jülich, Leo-Brandt-Str, Jülich D-52425, Germany.|Department of Environmental Nano-materials, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Zernike Institute for Advanced Materials, Department of Macromolecular Chemistry and New Polymeric Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Portale
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720 California, USA.
authors.forename: Chenhui
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich, Jülich D-52425, Germany.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Kentzinger
authors.affiliation: Department of Physics and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: James T
authors.initials: JT
authors.lastname: Gleeson
authors.affiliation: Department of Physics and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Antal
authors.initials: A
authors.lastname: Jakli
authors.affiliation: Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 5, Roma 00185, Italy.
authors.forename: Cristiano
authors.initials: C
authors.lastname: De Michele
authors.affiliation: Institute of Complex Systems ICS-3, JARA-SOFT, Forschungszentrum Jülich, Leo-Brandt-Str, Jülich D-52425, Germany.|Department of Physics, Heinrich-Heine-Universität Düsseldorf, Universitätsstrae 1, D-40225 Düsseldorf, Germany.
authors.forename: Jan K G
authors.initials: JK
authors.lastname: Dhont
authors.affiliation: Department of Physics and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Samuel
authors.initials: S
authors.lastname: Sprunt
authors.affiliation: Institute of Complex Systems ICS-3, JARA-SOFT, Forschungszentrum Jülich, Leo-Brandt-Str, Jülich D-52425, Germany.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Stiakakis
mesh_terms: D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry; D050866:Liquid Crystals / Q000737:chemistry; D008958:Models, Molecular; D009010:Monte Carlo Method; D009690:Nucleic Acid Conformation; D044367:Phase Transition; D013696:Temperature; D013816:Thermodynamics
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA