Andrew J Gross

Publications (5) View all

• Source

  Available from: Frankie J Rawson

  Article: Mediated electrochemical detection of electron transfer from the outer surface of the cell wall of Saccharomyces cerevisiae

  Frankie J. Rawson, Andrew J. Gross, David J. Garrett, Alison J. Downard, Keith H. R. Baronian
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  ABSTRACT: Catabolic electron transport processes in yeast are generally considered to be restricted to respiration, glycolysis and trans plasma membrane electron transport (tPMET) proteins. These processes are shielded from the external environment by the cell membrane and a thick cell wall. It has been recently proposed that electrons might be transferred directly from the yeast cell to electrodes. Here we provide the first experimental evidence for electron transfer from the external surface of a yeast cell to an electrode. The electrode has a stable mediator layer that is significantly thinner than the cell wall and unable to make direct contact with any known yeast redox centres. Current measured at the modified electrode in the presence of Saccharomyces cerevisiae is shown to originate both from exported soluble redox species and directly from the external surface of the cell wall. Highlights: ► An osmium polymer is attached to an electrode with a thin robust tether layer ► The modified electrode mediates electron transfer from yeast cells ► Electron transfer from the surface of the yeast cell wall to the electrode is demonstrated.
  Electrochemistry Communications 12/2011; 15(1):85-87. · 4.86 Impact Factor
• Article: Nickel (II) tetraphenylporphyrin modified surfaces via electrografting of an aryldiazonium salt

  Andrew J. Gross, Christophe Bucher, Liliane Coche-Guerente, Pierre Labbé, Alison J. Downard, Jean-Claude Moutet
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  ABSTRACT: We have prepared and isolated the monodiazonium salt of nickel (II) tetraphenylporphyrin and grafted the corresponding complex to glassy carbon, pyrolysed photoresist film, gold and indium tin oxide surfaces via reduction of the diazonium moiety. Characterisations of the films by voltammetry, UV–vis spectroscopy and atomic force microscopy depth profiling confirm that the metallated porphyrin is intact in the film and is stably attached to the surface with well-behaved, but highly solvent-dependent electrochemistry. Under the grafting conditions used, the films appear to have close to monolayer thickness with the porphyrin macrocycles oriented predominantly upright on the surface. Highlights: ► Monodiazonium salt of nickel (II) tetraphenylporphyrin is isolated. ► Stable films of the porphyrin are grafted by electroreduction of the diazonium salt. ► Films exhibit well-behaved electrochemistry and UV–vis absorption spectra. ► Proposed structure is a monolayer of porphyrins with close to vertical orientation.
  Electrochemistry Communications 11/2011; 13(11):1236-1239. · 4.86 Impact Factor
• Article: Regeneration of pyrolyzed photoresist film by heat treatment.

  Andrew J Gross, Alison J Downard
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  ABSTRACT: A simple, time-, and cost-effective procedure is described for regenerating film-modified or deactivated pyrolyzed photoresist film (PPF) surfaces. Heating for 30 min at 545 ± 25 °C in argon at a flow rate of 1 L min(-1) removes covalently bound thin organic films, attached via electrografting from aryldiazonium salt solutions. The heat-treated surfaces exhibit improved electrochemical characteristics compared to those prior to modification and can be reused for solution-based electrochemical measurements and for electrografting. The same treatment reactivates PPF electrodes that have been deactivated by exposure to adsorbates from air or solution. X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and water contact angle measurements establish that the regeneration procedure does not lead to significant changes in oxygen content, roughness, or hydrophobicity of PPF surfaces. XPS measurements also confirm the complete removal of covalently attached organic films after heat treatment but reveal a specific interaction between grafted nitrophenyl films and PPF which results in a small amount of N incorporation in the surface.
  Analytical Chemistry 02/2011; 83(6):2397-402. · 5.86 Impact Factor
• Article: A simple approach to patterned protein immobilization on silicon via electrografting from diazonium salt solutions.

  Benjamin S Flavel, Andrew J Gross, David J Garrett, Volker Nock, Alison J Downard
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  ABSTRACT: A highly versatile method utilizing diazonium salt chemistry has been developed for the fabrication of protein arrays. Conventional ultraviolet mask lithography was used to pattern micrometer sized regions into a commercial photoresist on a highly doped p-type silicon (100) substrate. These patterned regions were used as a template for the electrochemical grafting of the in situ generated p-aminobenzenediazonium cation to form patterns of aminophenyl film on silicon. Immobilization of biomolecules was demonstrated by coupling biotin to the aminophenyl regions followed by reaction with fluorescently labeled avidin and visualization with fluorescence microscopy. This simple patterning strategy is promising for future application in biosensor devices.
  ACS Applied Materials & Interfaces 04/2010; 2(4):1184-90. · 4.53 Impact Factor
• Article: Two-component mixed and patterned films on carbon surfaces through the photografting of arylazides.

  Andrew J Gross, Samuel S C Yu, Alison J Downard
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  ABSTRACT: Organic films have been grafted to glassy carbon surfaces by the photolysis of arylazides. Atomic force microscopy and electrochemical measurements reveal that the films are loosely packed. The methodology was expanded to prepare two-component thin films incorporating either a reactive tether species and a nonreactive background film or two different reactive tethers. Strategies were developed to generate both continuous mixed films and surfaces presenting patterns of two components. For patterning, the arylazide derivative was grafted onto previously modified glassy carbon surfaces. In this case, the first modification step is not limited to photografting, which increases the scope of the methods. For all grafted surfaces, the reactivity of tether species was confirmed by coupling electroactive targets to the tethers, followed by electrochemical monitoring. The ease of preparing surfaces with spatially controlled functionality offers promise for the design of sensing platforms on graphitic carbon substrates.
  Langmuir 02/2010; 26(10):7285-92. · 4.19 Impact Factor