title: Migration of phospholipid vesicles in response to OH(-) stimuli.
abstract: We demonstrate migration of phospholipid vesicles in response to a pH gradient. Upon simple micro-injection of a NaOH solution, the vesicles linearly moved to the tip of the micro-pipette and the migration velocity was proportional to the gradient of OH(-) concentration. Vesicle migration was characteristic of OH(-) ions and no migration was observed for monovalent salts or nonionic sucrose solutions. The migration of vesicles is quantitatively described by the surface tension gradient model where the hydrolysis of the phospholipids by NaOH solution decreases the surface tension of the vesicle. The vesicles move toward a direction where the surface energy decreases. Thus the chemical modification of lipids produces a mechanical force to drive vesicles.
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. imai@bio.phys.tohoku.ac.jp.
authors.forename: Atsuji
authors.initials: A
authors.lastname: Kodama
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. imai@bio.phys.tohoku.ac.jp.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Sakuma
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. imai@bio.phys.tohoku.ac.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Imai
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. imai@bio.phys.tohoku.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oya
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. imai@bio.phys.tohoku.ac.jp.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kawakatsu
authors.affiliation: Laboratoire Matière et Systèmes Complexes, University Paris Diderot - Paris 7, F-75013 Paris, France and Faculty of Physics, University Pierre & Marie Curie - Paris 6, F-75005 Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Puff
authors.affiliation: Laboratoire Matière et Systèmes Complexes, University Paris Diderot - Paris 7, F-75013 Paris, France and Faculty of Physics, University Pierre & Marie Curie - Paris 6, F-75005 Paris, France.
authors.forename: Miglena I
authors.initials: MI
authors.lastname: Angelova
mesh_terms: D006868:Hydrolysis; D009038:Motion; D010743:Phospholipids / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D013395:Sucrose / Q000737:chemistry; D013500:Surface Tension; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D010743:Phospholipids; D053835:Unilamellar Liposomes; D012972:Sodium Hydroxide; D013395:Sucrose