title: Collective conformations of DNA polymers assembled on surface density gradients.
abstract: To study dense double-stranded DNA (dsDNA) polymer phases, we fabricated continuous density gradients of binding sites for assembly on a photochemical interface and measured both dsDNA occupancy and extension using evanescent fluorescence. Despite the abundance of available binding sites, the dsDNA density saturates after occupation of only a fraction of the available sites along the gradient. The spatial position at which the density saturates marks the onset of collective stretching of dsDNA, a direct manifestation of balancing entropic and excluded-volume interactions. The methodology presented here offers a new means to investigate dense dsDNA compartments.
authors.affiliation: Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Shemer
authors.forename: Yahel
authors.initials: Y
authors.lastname: Atsmon
authors.forename: Eyal
authors.initials: E
authors.lastname: Karzbrun
authors.forename: Roy H
authors.initials: RH
authors.lastname: Bar-Ziv
mesh_terms: D002499:Centrifugation, Density Gradient; D004247:DNA / Q000737:chemistry*; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011108:Polymers; D004247:DNA