TY - JOUR A1 - Mak, Wing Cheung A1 - Cheung, Kwan Yee A1 - Trau, Dieter A1 - Warsinke, Axel A1 - Scheller, Frieder W. A1 - Renneberg, Reinhard T1 - Electrochemical bioassay utilizing encapsulated electrochemical active microcrystal biolabels N2 - A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a "supernova effect" upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal- generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (SIP) ratio of 10(4)-10(5). Microcrystal biolabels with different antibody surface coverage (1.60-5.05 mg m(-2)) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m(-2) showed a sensitivity of 3.93 nA g(- 1) L-1 with a detection limit of 2.82 g L-1 Y1 - 2005 SN - 0003-2700 ER - TY - JOUR A1 - Lettau, Kristian A1 - Gajovic-Eichelmann, N. A1 - Kwak, Young-Keun A1 - Scheller, Frieder W. A1 - Warsinke, Axel T1 - Hydroxylasen und katalytische Polymere für Biochips Y1 - 2004 ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Tiepner, K. A1 - Warsinke, Axel T1 - Anwendung von Biosensoren in der Lebensmittelanalytik Y1 - 2004 SN - 3-89947-120-2 ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Warsinke, Axel A1 - Pfeiffer, Dorothea A1 - Czeponik, J. T1 - Biosensorik / Bioanalytik Y1 - 2004 SN - 3-87081-372-5 ER - TY - JOUR A1 - Lettau, Kristian A1 - Warsinke, Axel A1 - Laschewsky, André A1 - Mosbach, K. A1 - Yilmaz, E. A1 - Scheller, Frieder W. T1 - An esterolytic imprinted polymer prepared via a silica-supported transition state analogue N2 - In this work we describe a new preparation method for an esterolytic imprinted polymer with catalytic sites on the surface. A template was prepared by immobilizing a transition state analogue (phosphoramidic acid derivative) of an esterolytic reaction within porous silica particles. Polymerization within the pores was carried out using 4- vinylimidazole as a functional monomer and divinylbenzene as a cross-linker. The polymer was released by dissolution of the silica support with hydrofluoric acid and catalytic properties were studied by incubation with three different 4- nitrophenylesters and spectrophotometric determination of the released 4-nitrophenol. For 4-nitrophenyl acetate an activity of 211 nmol min(-1) mg(-1) and a K-m value of 2.2 mmol L-1 was obtained Y1 - 2004 ER - TY - JOUR A1 - Pieper-Fürst, U. A1 - Kleuser, U. A1 - Stöcklein, Walter F. M. A1 - Warsinke, Axel A1 - Scheller, Frieder W. T1 - Detection of subicomolar concentrations of human matrix metalloproteinase-2 by an optical biosensor N2 - We describe in this paper the development of a one-step sandwich assay for the highly sensitive and fast detection of human matrix metalloproteinase (MMP)-2 (EC 3.4.24.24), using surface plasmon resonance (SPR). For the assay, two ligands were selected: monoclonal anti-MMP-2 antibody Ab-2 and the tissue inhibitor of metalloproteinases (TIMP)-2. They were chosen on the basis of (1) their affinities to MMP-2, (2) the efficiency of immobilization to the sensor chip, (3) the efficiency of adsorption to colloidal gold, and (4) the stability of these protein-coated gold particles. The assay included mixing of MMP-2 with antibody Ab-2 adsorbed to colloidal gold with a diameter of about 20 rim and injection into the flowcell of the SPR instrument containing immobilized TIMP-2. By using colloidal gold particles an amplification factor of 114 and a detection limit of 0.5 pM for MMP-2 were obtained. The precision of the assay was high even at low analyte concentrations, the standard deviation being 8.3% for five determinations of 1 pM MMP- 2. No significant binding was observed with the structurally related MMP-9. The assay is far more sensitive and faster than commonly used methods for MMP-2 detection. As TIMP-bound MMP-2 is not detected by this method, the assay can be applied for measuring free MMP-2, reflecting the imbalance of free and inhibitor-bound enzyme in various pathological situations. (C) 2004 Elsevier Inc. All rights reserved Y1 - 2004 ER - TY - JOUR A1 - Warsinke, Axel A1 - Lettau, Kristian A1 - Werner, Deljana A1 - Micheel, Burkhard A1 - Kwak, Young-Keun T1 - Biomimetic Binders and Catalysts for Sensorics = Biomimetische Binder und Katalysatoren für die Sensorik N2 - Biosensors which make use of the high specificity of enzymes, antibodies, and nucleic acids have been described for detection of numerous metabolites, hormones, and nucleic acid sequences. In addition to biological components nowadays biomimetic recognition molecules are also used. Especially antibodies, aptamers, and molecular imprints are promising biomimetics. They could broaden the range of detectable analytes and could increase the functional stability of the sensor. In this publication we describe the generation of biomimetic antibodies and biomimetic molecular imprints for binding creatinine and for hydrolyzing phenylcarbamates to be used in electrochemical sensors. Y1 - 2003 UR - http://www.extenza-eps.com/extenza/loadHTML?objectIDValue=21853&type=abstract ER - TY - JOUR A1 - Stoellner, Daniela A1 - Scheller, Frieder W. A1 - Warsinke, Axel T1 - Activation of cellulose membranes with 1,1ï-carbonyldiimidazole or 1-cyano-4-4-dimethylaminopyridinium tetrafluoroborate as a basis for the development of immunosensors Y1 - 2002 ER - TY - JOUR A1 - Stöllner, Daniela A1 - Stöcklein, Walter F. M. A1 - Scheller, Frieder W. A1 - Warsinke, Axel T1 - Membrane-immobilized haptoglobin as affinity matrix for a hemoglobin-A1c-immunosensor Y1 - 2002 ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Bauer, Christian G. A1 - Makower, Alexander A1 - Wollenberger, Ursula A1 - Warsinke, Axel A1 - Bier, Frank Fabian T1 - Immunoassays using enzymatic amplification electrodes Y1 - 2002 SN - 0-7484-0791-X ER -