title: Electrochemistry of single metalloprotein and DNA-based molecules at Au(111) electrode surfaces.
abstract: We have briefly overviewed recent efforts in the electrochemistry of single transition metal complex, redox metalloprotein, and redox-marked oligonucleotide (ON) molecules. We have particularly studied self-assembled molecular monolayers (SAMs) of several 5'-C6-SH single- (ss) and double-strand (ds) ONs immobilized on Au(111) electrode surfaces via Au-S bond formation, using a combination of nucleic acid chemistry, electrochemistry and electrochemically controlled scanning tunnelling microscopy (in situ STM). Ds ONs stabilized by multiply charged cations and locked nucleic acid (LNA) monomers have been primary targets, with a view on stabilizing the ds-ONs and improving voltammetric signals of intercalating electrochemical redox probes. Voltammetric signals of the intercalator anthraquinone monosulfonate (AQMS) at ds-DNA/Au(111) surfaces diluted by mercaptohexanol are significantly sharpened and more robust in the presence than in the absence of [Co(NH3)6](3+). AQMS also displays robust Faradaic voltammetric signals specific to the ds form on binding to similar LNA/Au(111) surfaces, but this signal only evolves after successive voltammetric scanning into negative potential ranges. Triply charged spermidine (Spd) invokes itself a strong voltammetric signal, which is specific to the ds form and fully matched sequences. This signal is of non-Faradaic, capacitive origin but appears in the same potential range as the Faradaic AQMS signal. In situ STM shows that molecular scale structures of the size of Spd-stabilized ds-ONs are densely packed over the Au(111) surface in potential ranges around the capacitive peak potential.
authors.affiliation: Department of Chemistry, Kemitorvet, Building 207, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
authors.forename: Princia
authors.initials: P
authors.lastname: Salvatore
authors.forename: Dongdong
authors.initials: D
authors.lastname: Zeng
authors.forename: Kasper K
authors.initials: KK
authors.lastname: Karlsen
authors.forename: Qijin
authors.initials: Q
authors.lastname: Chi
authors.forename: Jesper
authors.initials: J
authors.lastname: Wengel
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
mesh_terms: D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D008667:Metalloproteins / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D008667:Metalloproteins; D006046:Gold; D004247:DNA
keywords: DNA; electrochemistry; gold; in situ STM; metalloproteins