This is the institutional Repository of the Helmholtz Centre for Infection Research in Braunschweig/Germany (HZI), the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken/Germany, the TWINCORE Zentrum für Exprerimentelle und Klinische Infektionsforschung, Hannover/Germany,Helmholtz-Institut für RNA-basierte Infektionsforschung (HIRI), Würzburg/Germany, Braunschweig Integrated Centre for Systems biology (BRICS), Centre for Structural Systems Biology (CSSB) the Study Centre Hannover, Hannover/Germany and the Centre for Individualised Infection Medicine (CiiM).

 

  • PIEZOELECTRIC (PZ) IMMUNOSENSORS AND THEIR APPLICATIONS

    Suleiman, Ahmad A.; Guibault, George G.; Department of Chemistry University of New Orleans New Orleans, LA 70148 (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1992)
    The recent development of piezoelectric immunosensors is reviewed. The selectivity provided by the biological coatings together with the inherent sensitivity of the PZ devices and the ability to oscillate the crystal in liquid medium have induced a rising interest in this class of sensors. Methods of coating and several applications are reported including microgravimetric immunoassays, microbial assays and gas phase immunosensors.
  • BIOCHEMICAL CHARACTERIZATION OFA HIGHLY SPECIFIC TRIMETHYLAMINE DEHYDROGENASE SUITED FOR THE APPLICATION IN BIOSENSORS

    Hummel, W.; Wendel, U.; Sting, Susanne; Institut für Enzymtechnologie der Heinrich-Heine-Universität Düsseldorf; Forschungszentrum Jülich, Pf 2050, D-5170 Jülich; Kinderklinik der Heinrich-Heine-Universität Düsseldorf, Moorenstr. 5, D-4000 Düsseldorf (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1992)
    A strain of Paracoccus possessing a NAD (P)*-independent trimethylamine dehydrogenase could be isolated by enrichment cultivation. The enzyme was purified up to 4.2 U/mg. Phenazine ethosulfate acts as an electron acceptor, other artificial mediators such as methylene blue or K3[Fe(CN)¢] are inactive. Important biochemical data are: pH-optimum: 9.0; substrates: specific for trimethylamine; dimethylamine, methylamine or $rimethylamine-N-oxide are not converted; Ky(trimethylamine): 6.6*¢10°° M. The calibration curve for trimethylamine (aqueous solution) using a kinetic photometric assay with dichlorophenol-indophenol shows a linearity between 0.1 - 0.8 uM trimethylamine.
  • GRAPHITE BASED BIENZYME SENSORS

    Kulys, Juozas J.; Bilitewski, Ursula; Schmid, Rolf D.; GBF- Gesellschaft fiir Biotechnologische Forschung mbH, Project Group Biosensors, Mascheroder Weg 1, W- 3300 Braunschweig (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1992)
    Robust peroxidase/oxidase sensors based on both chemically modified and unmodified graphite electrodes were prepared. The sensorsacted atelectrode potentials of -0.2 V to 0.2 V vs Ag/AgCl electrode. The Sensors werespecific to glucose, alcohols, choline chloride, L- and D-amino acids and oxalic acid. The sensitivities of sensors ranged from 0.3 - 12 uA/mM and the determination ranges of metabolites were 0.01 - 20 mM. The concentration range of cholesterine determined using a hydrogen peroxide sensor and soluble cholesterol oxidase was 0.01 - 0.26 mM with a sensitivity of 0.25 mA/mM whendetermination was carried out using the in biocatalytic pre-concentration regime. The pH optima andthe longterm stabilities of the sensors depended largely on the properties of the oxidase immobilized
  • BIOSENSOR SYSTEMSUTILIZING NADH AS AN INTERMEDIATE

    Risinger, Lars; Skoog, Mikael; Yang, Xiurong; Moges, Ghirma; Johansson, Gillis; DepartmentofAnalytical Chemistry, University of Lund P.O. Box 124, S-221 00 Lund, Sweden (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1992)
    The combination of dehydrogenases and chemically modified graphite electrodes has proved particularly useful in the developmentof highly selective and sensitive biosensor systems. Amongthe applications given is a flow injection system for the determination of fructose with a linear range of 1 pM - 2 mM.As a means toincrease sensitivity further, substrate recycling was employed in the determination of ATP down to the nano-molar level. A creatine and creatinine assayillustrates the potential of coupled equilibria and coimmobilized enzymes. For the determination ofglucose in whole blood a dialyzer was integrated with a biosensor. The hematocrit dependence on the transfer of glucose through the dialysis membrane was studied.
  • NICKELOCENE AS ELECTROCHEMICAL MEDIATOR FOR GLUCOSE OXIDASE IMMOBILIZED ON PYROLYTIC GRAPHITE ELECTRODE

    Atanasov, P.; Kaisheva, A.; Gamburzev, S.; Iliev, I.; Bobrin, S.; Central Laboratory of Electrochemical Power Sources Bulgarian Academy of Sciences, Sofia 1113, Bulgaria; Frumkin Institute of Electrochemistry Soviet Academy of Sciences, Moscow, USSR (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1992)
    Nickelocene is investigated as an electrochemical mediator in glucose oxidase amperometric electrodes. The formal redox potential of nicKelocene /nickelocenium obtained in adsorbed state on electrochemically pre-treated (activated) pyrolytic graphite electrode,is -0.1 V (vs. Ag/AgCl). Adsorbed nickelocene mediates the charge transfer between the electrode and glucose oxidase. The steady-state amperometric response of nickelocene mediated enzyme electrode is investigated as a function of the glucose concentration, applied potential and pH of electrolyte.

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