Ulla Wollenberger

Publications (102) View all

• Article: A Biosensor for Aromatic Aldehydes Comprising the Mediator Dependent PaoABC-Aldehyde Oxidoreductase

  Artavazd Badalyan, Meina Neumann-Schaal, Silke Leimkühler, Ulla Wollenberger
  Electroanalysis 01/2013; 25(1):101-108. · 2.87 Impact Factor
• Article: Bioelectrocatalysis at mesoporous antimony doped tin oxide electrodes - electrochemical characterization and direct enzyme communication

  Stefano Frasca, Anabel Molero Milan, Amandine Guiet, Caren Goebel, Fernando Pérez-Caballero, Konstanze Stiba, Silke Leimkühler, Anna Fischer, Ulla Wollenberger
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  ABSTRACT: In this paper we report immobilization and bioelectrocatalysis of human sulfite oxidase (hSO) on nanostructured antimony doped tin oxide (ATO) thin film electrodes. Two types of ATO thin film electrodes were prepared via evaporation induced self-assembly of ATO nanoparticle sols. The use of a porogen results in different porosity and film thickness. Nevertheless both electrode types reveal similar quasi reversible electrochemical behavior for positive and negatively charged small mediators. Facile and durable immobilization of catalytically active enzyme in a direct electron transfer configuration was achieved without further chemical modification of the ATO surfaces. Interestingly, the binding of hSO onto the ATO surface seem to be not only of electrostatic nature, but also originates from a strong interaction between the histidine-tag of the enzyme and the supporting material. This is suggested from stable sulfite dependent bioelectrocatalytic signals at high ionic strength and imidazole desorption experiments. As such, ATO appears as a promising conductive platform for the immobilization of complex enzymes and their application in bioelectrocatalysis.
  Electrochimica Acta 01/2013; · 3.83 Impact Factor
• Article: The aromatic peroxygenase from Marasmius rutola--a new enzyme for biosensor applications.

  Aysu Yarman, Glenn Gröbe, Bettina Neumann, Mathias Kinne, Nenad Gajovic-Eichelmann, Ulla Wollenberger, Martin Hofrichter, René Ullrich, Katrin Scheibner, Frieder W Scheller
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  ABSTRACT: The aromatic peroxygenase (APO; EC 1.11.2.1) from the agraric basidomycete Marasmius rotula (MroAPO) immobilized at the chitosan-capped gold-nanoparticle-modified glassy carbon electrode displayed a pair of redox peaks with a midpoint potential of -278.5 mV vs. AgCl/AgCl (1 M KCl) for the Fe(2+)/Fe(3+) redox couple of the heme-thiolate-containing protein. MroAPO oxidizes aromatic substrates such as aniline, p-aminophenol, hydroquinone, resorcinol, catechol, and paracetamol by means of hydrogen peroxide. The substrate spectrum overlaps with those of cytochrome P450s and plant peroxidases which are relevant in environmental analysis and drug monitoring. In M. rotula peroxygenase-based enzyme electrodes, the signal is generated by the reduction of electrode-active reaction products (e.g., p-benzoquinone and p-quinoneimine) with electro-enzymatic recycling of the analyte. In these enzyme electrodes, the signal reflects the conversion of all substrates thus representing an overall parameter in complex media. The performance of these sensors and their further development are discussed.
  Analytical and Bioanalytical Chemistry 01/2012; 402(1):405-12. · 3.78 Impact Factor
• Article: Enzyme electrode for aromatic compounds exploiting the catalytic activities of microperoxidase-11.

  Aysu Yarman, Artavazd Badalyan, Nenad Gajovic-Eichelmann, Ulla Wollenberger, Frieder W Scheller
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  ABSTRACT: Microperoxidase-11 (MP-11) which has been immobilised in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode catalyzes the conversion of aromatic substances. This peroxide-dependent catalysis of microperoxidase has been applied in an enzyme electrode for the first time to indicate aromatic compounds such as aniline, 4-fluoroaniline, catechol and p-aminophenol. The electrode signal is generated by the cathodic reduction of the quinone or quinoneimine which is formed in the presence of both MP-11 and peroxide from the substrate. The same sensor principle will be extended to aromatic drugs.
  Biosensors & bioelectronics 12/2011; 30(1):320-3. · 5.43 Impact Factor
• Article: Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode.

  Stefano Frasca, Oscar Rojas, Johannes Salewski, Bettina Neumann, Konstanze Stiba, Inez M Weidinger, Brigitte Tiersch, Silke Leimkühler, Joachim Koetz, Ulla Wollenberger
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  ABSTRACT: The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl(4) with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2 s, a linear detection range between 0.5 and 5.4 μM with a high sensitivity (1.85 nA μM(-1)). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples.
  Bioelectrochemistry (Amsterdam, Netherlands) 12/2011; 87:33-41. · 2.65 Impact Factor