TY - JOUR A1 - Frasca, Stefano A1 - von Graberg, Till A1 - Feng, Jiu-Ju A1 - Thomas, Arne A1 - Smarsly, Bernd M. A1 - Weidinger, Inez M. A1 - Scheller, Frieder W. A1 - Hildebrandt, Peter A1 - Wollenberger, Ursula T1 - Mesoporous indium tin oxide as a novel platform for bioelectronics N2 - Stable immobilization and reversible electrochemistry of cytochrome c in a tranparent indium tin oxide film with a well-defined mesoporosity (mpITO) is demonstrated. the transparency and good conductivity, in combination with the large surface area of mpITO, allow the incorporation of a high amount of elelctroactive biomolecules and their electrochemical and spectroscopic investigation. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry are employed for the characterization of cytochrome c immobilized in the mpITO and reveal no perturbant of the structural of the integrity of the redox protein. The potential of this modified material as a biosensor detection of superoxide anions is also demonstrated. Y1 - 2010 UR - http://www3.interscience.wiley.com/journal/122208635/home U6 - https://doi.org/10.1002/cctc.201000047 SN - 1867-3880 ER - TY - JOUR A1 - Frasca, Stefano A1 - Rojas, Oscar A1 - Salewski, Johannes A1 - Neumann, Bettina A1 - Stiba, Konstanze A1 - Weidinger, Inez M. A1 - Tiersch, Brigitte A1 - Leimkühler, Silke A1 - Koetz, Joachim A1 - Wollenberger, Ursula T1 - Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode JF - Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society N2 - 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 HAuCl4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10 nm. 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 mu M with a high sensitivity (1.85 nA mu M-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. KW - Direct electron transfer KW - Gold nanoparticle KW - Human sulfite oxidase KW - Ionic liquid KW - Sulfite biosensor Y1 - 2012 U6 - https://doi.org/10.1016/j.bioelechem.2011.11.012 SN - 1567-5394 VL - 87 SP - 33 EP - 41 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Bergner, Andre A1 - Frasca, M. A1 - Sciuto, G. A1 - Buscarino, A. A1 - Ngamga, Eulalie Joelle A1 - Fortuna, L. A1 - Kurths, Jürgen T1 - Remote synchronization in star networks JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - We study phase synchronization in a network motif with a starlike structure in which the central node's (the hub's) frequency is strongly detuned against the other peripheral nodes. We find numerically and experimentally a regime of remote synchronization (RS), where the peripheral nodes form a phase synchronized cluster, while the hub remains free with its own dynamics and serves just as a transmitter for the other nodes. We explain the mechanism for this RS by the existence of a free amplitude and also show that systems with a fixed or constant amplitude, such as the classic Kuramoto phase oscillator, are not able to generate this phenomenon. Further, we derive an analytic expression which supports our explanation of the mechanism. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevE.85.026208 SN - 1539-3755 VL - 85 IS - 2 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Frasca, Stefano A1 - Richter, Claudia A1 - von Graberg, Till A1 - Smarsly, Bernd M. A1 - Wollenberger, Ursula T1 - Electrochemical switchable protein-based optical device JF - Engineering in life sciences : Industry, Environment, Plant, Food N2 - The present work contributes to the development of reusable sensing systems with a visual evaluation of the detection process related to an analyte. An electrochemical switchable protein-based optical device was designed with the core part composed of cytochrome c immobilized in a mesoporous indium tin oxide film. A color-developing redox-sensitive dye was used as switchable component of the system. The cytochrome c-catalyzed oxidation of the dye by hydrogen peroxide is spectroscopically investigated. When the dye is co-immobilized with the protein, its redox state is easily controlled by application of an electrical potential at the supporting material. This enables to electrochemically reset the system to the initial state and repetitive signal generation. The implemented reset function of the color forming reaction will make calibration of small test devices possible. The principle can be extended to other color forming redox reactions and to coupled enzyme systems, such as rapid food testing and indication of critical concentrations of metabolites for health care. KW - Cytochrome c KW - Electrochemical switch KW - Indium tin oxide KW - mesoporous materials KW - Optical device Y1 - 2011 U6 - https://doi.org/10.1002/elsc.201100079 SN - 1618-0240 VL - 11 IS - 6 SP - 554 EP - 558 PB - Wiley-Blackwell CY - Malden ER -