title: Biomimetics with a self-assembled monolayer of catalytically active tethered isoalloxazine on Au.
abstract: A new biomimetic nanostructured electrocatalyst comprised of a self-assembled monolayer (SAM) of flavin covalently attached to Au by reaction of methylformylisoalloxazine with chemisorbed cysteamine is introduced. Examinations by Fourier transform infrared spectroscopy and scanning tunneling microscopy (STM) show that the flavin molecules are oriented perpendicular to the surface with a 2 nm separation between flavin molecules. As a result of the contrast observed in the STM profiles between areas only covered by unreacted cysteamine and those covered by flavin-cysteamine moieties, it can be seen that the flavin molecules rise 0.7 nm above the chemisorbed cysteamines. The SAM flavin electrocatalyst undergoes fast electron transfer with the underlying Au and shows activity toward the oxidation of enzymatically active beta-NADH at pH 7 and very low potential (-0.2 V vs Ag/AgCl), a requirement for use in an enzymatic biofuel cell, and a 100-fold increase in activity with respect to the collisional reaction in solution.
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE, Ciudad Universitaria, AR-1428 Buenos Aires, Argentina. calvo@qi.fcen.uba.ar
authors.forename: Ernesto J
authors.initials: EJ
authors.lastname: Calvo
authors.forename: M Silvina
authors.initials: MS
authors.lastname: Rothacher
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bonazzola
authors.forename: Ian R
authors.initials: IR
authors.lastname: Wheeldon
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Salvarezza
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Vela
authors.forename: Guillermo
authors.initials: G
authors.lastname: Benitez
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D003543:Cysteamine / Q000737:chemistry; D004563:Electrochemistry; D005415:Flavins / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D016252:Microscopy, Scanning Tunneling; D015394:Molecular Structure; D009243:NAD / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D005415:Flavins; D008567:Membranes, Artificial; C518529:methylformylisoalloxazine; D009243:NAD; D003543:Cysteamine; D006046:Gold