title: Interfacial Au nanoparticle decoration of a disulfide modified G-wire.
abstract: The guanine-rich oligonucleotide (GRO), dGGGGTTGGGG (G4T2G4), has the capacity to form a linear supramolecular polymer known as a G-wire. Individual nucleotides of the component GROs can be functionally modified to serve as site-specific attachment points in the G-wire while not interfering with its self-assembling properties. An amine linker modification to an internal thymine base of the GRO, denoted G4TT*G4, serves as a chemically versatile attachment site.
  
  
  
  In this work, addition of an alkyl disulfide to G4TT*G4produces the GRO G4TTdG4enabling binding to gold nanoparticles via place exchange chemistry. G-wires assembled by combining G4T2G4and G4TTdG4were stably maintained in an aqueous environment. Disulfide modified G-wires (DS_G-wire) were then covered with dodecanethiol capped gold nanoparticles in an organic solvent via an interfacial place exchange reaction. Tapping Mode AFM and TEM were used to image G-wires decorated with gold nanoparticles. The specificity of the interfacial place exchange reaction was measured using a fluorometric dye displacement from the gold nanoparticles.
  
  
  
  The results show that a two component DS_G-wire with an amphipathic tether readily self-assemble as shown by PAGE and TM-AFM. The amphipathic disulfide moiety of DS_G-wires facilitates place exchange chemistry with alkylthiol protected Au nanoparticles across an aqueous-organic interface.
  
  
  
  Interfacial place exchange is an effective strategy for decorating DS_G-wires with Au nanoparticles.
  
  
  
  The use of modified G-wire self-assembly combined with a high degree of nanoparticle binding specificity presents another strategy for the use of G-wires as a rigid one-dimensional molecular scaffold with potential applications in nanoscale device construction. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
authors.affiliation: Department of Chemistry, University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, USA. Electronic address: brg3c@virginia.edu.
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Goblirsch
authors.affiliation: Department of Chemistry, University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, USA. Electronic address: evan.kalb@stthomas.edu.
authors.forename: Evan M
authors.initials: EM
authors.lastname: Kalb
authors.affiliation: Department of Chemistry, University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, USA. Electronic address: tcmarsh@stthomas.edu.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Marsh
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D001665:Binding Sites; D004220:Disulfides / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D054856:G-Quadruplexes; D006046:Gold / Q000737:chemistry*; D006151:Guanosine / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D008752:Methylene Chloride / Q000737:chemistry; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D009841:Oligonucleotides / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D004220:Disulfides; D008024:Ligands; D009841:Oligonucleotides; D013501:Surface-Active Agents; D006151:Guanosine; D008752:Methylene Chloride; D006046:Gold; C011934:mica
keywords: G-quartet; G-wire; Nanoparticle