title: Lateral distribution of charged species along a polyelectrolyte probed with a fluorescence blob model.
abstract: The distribution of metal counterions binding onto the oppositely charged surface of a model polyelectrolyte, namely, DNA, was characterized by conducting fluorescence quenching experiments. In these experiments, DNA was used as a molecular ruler to measure the average distance (d(blob)) over which electron transfer takes place between DNA-intercalated ethidium bromide (DNA-EB) and the electrostatically bound divalent metal cations Ni(2+) and Cu(2+). Analysis of the fluorescence decays of DNA-EB quenched by Cu(2+) and Ni(2+) with the fluorescence blob model showed that d(blob) was equal to the Debye length (κ(-1)). This surprisingly simple result considering the overall complexity of the system under study led to the straightforward proposal that counterions bind to a polyelectrolyte by distributing themselves randomly into an array of self-defined subdomains of dimension κ(-1). In turn, this insight can be utilized to rationalize the complex behavior of polyelectrolytes in aqueous solution.
authors.affiliation: Institute of Polymer Research, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Christine
authors.initials: C
authors.lastname: Keyes
authors.forename: Manoj
authors.initials: M
authors.lastname: Mathew
authors.forename: Jean
authors.initials: J
authors.lastname: Duhamel
mesh_terms: D002413:Cations, Divalent / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D004996:Ethidium / Q000737:chemistry*; D005453:Fluorescence; D007364:Intercalating Agents / Q000737:chemistry*; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry
chemical_list: D002413:Cations, Divalent; D007364:Intercalating Agents; D003300:Copper; D009532:Nickel; D004247:DNA; D004996:Ethidium