title: Shape anisotropy of a single random-walk polymer.
abstract: Random walks have been used to describe a wide variety of systems ranging from cell colonies to polymers. Sixty-five years ago, Kuhn [Kuhn, W. (1934) Kolloid-Z. 68, 2-11] made the prediction, backed later by computer simulations, that the overall shape of a random-walk polymer is aspherical, yet no experimental work has directly tested Kuhn's general idea and subsequent computer simulations. By using fluorescence microscopy, we monitored the conformation of individual, long, random-walk polymers (fluorescently labeled DNA molecules) at equilibrium. We found that a polymer most frequently adopts highly extended, nonfractal structures with a strongly anisotropic shape. The ensemble-average ratio of the lengths of the long and short axes of the best-fit ellipse of the polymer was much larger than unity.
authors.affiliation: Department of Chemical Engineering and Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
authors.forename: C
authors.initials: C
authors.lastname: Haber
authors.forename: S A
authors.initials: SA
authors.lastname: Ruiz
authors.forename: D
authors.initials: D
authors.lastname: Wirtz
mesh_terms: D016880:Anisotropy; D011108:Polymers / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D011108:Polymers