TY - JOUR A1 - Lütkecosmann, Steffi A1 - Warsinke, Axel A1 - Tschöpe, Winfried A1 - Eichler, Rüdiger A1 - Hanack, Katja T1 - A novel monoclonal antibody suitable for the detection of leukotriene B4 JF - Biochemical and biophysical research communications N2 - Leukotriene B4 as an inflammatory mediator is an important biomarker for different respiratory diseases like asthma, chronic obstructive pulmonary disease or cystic lung fibrosis. Therefore the detection of LTB4 is helpful in the diagnosis of these pulmonary diseases. However, until now its determination in exhaled breath condensates suffers from problems of accuracy. Reasons for that could be improper sample collection and preparation methods of condensates and the lack of consistently assay specificity and reproducibility of the used immunoassay detection system. In this study we describe the development and the characterization of a specific monoclonal antibody (S27BC6) against LTB4, its use as molecular recognition element for the development of an enzyme-linked immunoassay to detect LTB4 and discuss possible future diagnostic applications. KW - Leukotriene B4 KW - Monoclonal antibody KW - Immunosensor KW - Chronic obstructive pulmonary disease (COPD) KW - Hapten Y1 - 2017 U6 - https://doi.org/10.1016/j.bbrc.2016.11.157 SN - 0006-291X SN - 1090-2104 VL - 482 IS - 4 SP - 1054 EP - 1059 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Guha, S. A1 - Warsinke, Axel A1 - Tientcheu, Charles Merlin A1 - Schmalz, K. A1 - Meliani, C. A1 - Wenger, Ch. T1 - Label free sensing of creatinine using a 6 GHz CMOS near-field dielectric immunosensor JF - The analyst : the analytical journal of the Royal Society of Chemistry N2 - In this work we present a CMOS high frequency direct immunosensor operating at 6 GHz (C-band) for label free determination of creatinine. The sensor is fabricated in standard 0.13 mu m SiGe:C BiCMOS process. The report also demonstrates the ability to immobilize creatinine molecules on a Si3N4 passivation layer of the standard BiCMOS/CMOS process, therefore, evading any further need of cumbersome post processing of the fabricated sensor chip. The sensor is based on capacitive detection of the amount of non-creatinine bound antibodies binding to an immobilized creatinine layer on the passivated sensor. The chip bound antibody amount in turn corresponds indirectly to the creatinine concentration used in the incubation phase. The determination of creatinine in the concentration range of 0.88-880 mu M is successfully demonstrated in this work. A sensitivity of 35 MHz/10 fold increase in creatinine concentration (during incubation) at the centre frequency of 6 GHz is gained by the immunosensor. The results are compared with a standard optical measurement technique and the dynamic range and sensitivity is of the order of the established optical indication technique. The C-band immunosensor chip comprising an area of 0.3 mm(2) reduces the sensing area considerably, therefore, requiring a sample volume as low as 2 mu l. The small analyte sample volume and label free approach also reduce the experimental costs in addition to the low fabrication costs offered by the batch fabrication technique of CMOS/BiCMOS process. Y1 - 2015 U6 - https://doi.org/10.1039/c4an02194k SN - 0003-2654 SN - 1364-5528 VL - 140 IS - 9 SP - 3019 EP - 3027 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Grießner, Matthias A1 - Hartig, Dave A1 - Christmann, Alexander A1 - Ehrentreich-Förster, Eva A1 - Warsinke, Axel A1 - Bier, Frank Fabian T1 - Surface regeneration of microfluidic microarray printheads through plasma techniques N2 - This work describes a method for surface regeneration of microfluidic microarray printheads through plasma techniques. Modification procedures were chosen in a way to obtain high reproducibility with a minimum of time consumption. The idea behind this is a complete regeneration of a microarray printhead before or after usage to achieve best printing results over a typical print job. A sequence of low-pressure oxygen-plasma and plasma polymerization with hexamethyldisiloxane (HMDSO) was used to regenerate printheads. Proof of the concept is given through quality control performed with a spotter implemented CCD camera, contact angle measurements and a typical hybridization experiment. Stable printing results were obtained over 3000 activations showing that the presented method is suitable for treatment of microarray printheads. Y1 - 2010 UR - http://iopscience.iop.org/0960-1317/ U6 - https://doi.org/10.1088/0960-1317/20/3/037002 SN - 0960-1317 ER - TY - JOUR A1 - Warsinke, Axel T1 - Point-of-care testing of proteins N2 - Point-of-care testing (POCT) is a fast developing area in clinical diagnostics that is considered to be one of the main driving forces for the future in vitro diagnostic market. POCT means decentralized testing at the site of patient care. The most important POCT devices are handheld blood glucose sensors. In some of these sensors, after the application of less than 1 A mu l whole blood, the results are displayed in less than 10 s. For protein determination, the most commonly used devices are based on lateral flow technology. Although these devices are convenient to use, the results are often only qualitative or semiquantitative. The review will illuminate some of the current methods employed in POCT for proteins and will discuss the outlook for techniques (e.g., electrochemical immunosensors) that could have a great impact on future POCT of proteins. Y1 - 2009 UR - http://www.springerlink.com/content/100417 U6 - https://doi.org/10.1007/s00216-008-2572-0 SN - 1618-2642 ER - TY - JOUR A1 - Sellrie, Frank A1 - Warsinke, Axel A1 - Micheel, Burkhard T1 - Homogeneous indirect fluorescence quenching immunoassay for the determination of low molecular weight substances JF - Analytical & bioanalytical chemistry N2 - This paper describes the principle of a homogeneous indirect fluorescence quenching immunoassay that uses monoclonal antibodies. It is a carrier-free assay system that is performed completely in solution. The assay system was established for the determination of a low molecular weight substance (hapten), the herbicide diuron, used as a model analyte. A fluorescein-monuron conjugate together with a fluorescence-quenching monoclonal anti-fluorescein antibody and an anti-analyte antibody (here an anti-diuron/monuron monoclonal antibody) were used as central components of the assay. The fluorescein-monuron conjugate can be bound either by the anti-fluorescein monoclonal antibody or by the anti-diuron/ monuron monoclonal antibody. Due to steric hindrance, binding of both antibodies to the conjugate was not possible at the same time. By selecting the antibody concentrations appropriately, a dynamic equilibrium can be established that permits the preferential binding of the anti-diuron/monuron antibody to the conjugate, which allows the fluorescein in the conjugate to fluoresce. This equilibrium can be easily altered by adding free analyte (diuron), which competes with the conjugate to bind to the anti-diuron/monuron antibody. A reduction of anti-diuron/monuron antibody binding to the conjugate results in an increase in the binding of the anti-fluorescein antibody, which leads to a decrease in the fluorescence of the conjugate. The fluorescence is therefore a direct indicator of the state of equilibrium of the system and thus also the presence of free unconjugated analyte. The determination of an analyte based on this test principle does not require any washing steps. After the test components are mixed, the dynamic equilibrium is rapidly reached and the results can be obtained in less than 5 min by measuring the fluorescence of the fluorescein. We used this test principle for the determination of diuron, which was demonstrated for concentrations of approximately 5 nM. Y1 - 2008 UR - http://www.springerlink.com/content/n7227875454216v7/ VL - 386 IS - 2 SP - 206 EP - 210 ER - TY - JOUR A1 - Halámek, Jan A1 - Wollenberger, Ursula A1 - Stöcklein, Walter F. M. A1 - Warsinke, Axel A1 - Scheller, Frieder W. T1 - Signal amplification in immunoassays using labeling via boronic acid binding to the sugar moiety of immunoglobulin G : proof of concept for glycated hemoglobin N2 - A novel electrochemical immunoassay based on the multiple affinity labeling of the indicator antibody with an electro-active tag is presented. The concept is illustrated for the determination of the glycated hemoglobin HbA1c in hemoglobin samples. Hemoglobin is adsorbed to the surfactant-modified surface of a piezoelectric quartz crystal. Whereas the quartz crystal nanobalance is used to validate the total Hb binding, the HbA1c on the sensor surface is recognized by an antibody and quantified electrochemically after the sugar moieties of the antibody have been labeled in-situ with ferroceneboronic acid. The sensitivity of this sensor is about threefold higher than the sensitivity of a hemoglobin sensor, where the ferroceneboronic acid is bound directly to HbA1c. Y1 - 2007 UR - http://www.informaworld.com/openurl?genre=journal&issn=0003-2719 U6 - https://doi.org/10.1080/00032710701327096 SN - 0003-2719 ER - TY - THES A1 - Warsinke, Axel T1 - Von Enzymen zu biomimetischen Polymeren : neue Perspektiven für die Bioanalytik Y1 - 2006 CY - Potsdam ER - TY - JOUR A1 - Nagel, Birgit A1 - Warsinke, Axel T1 - Towards separation-free electrochemical affinity sensors by using antibodies, aptamers and molecularly imprinted polymers : a review Y1 - 2006 U6 - https://doi.org/10.1080/00032710600853903 ER - TY - JOUR A1 - Lettau, Kristian A1 - Warsinke, Axel A1 - Katterle, Martin A1 - Danielsson, Bengt A1 - Scheller, Frieder W. T1 - A bifunctional molecularly imprinted polymer (MIP): analysis of binding and catalysis by a thermistor N2 - Binding or catalysis? Both can be distinguished with a molecularly imprinted polymer (MIP) by the different patterns of heat generation. The catalytically active sites, like in the corresponding enzyme, generate a steady-state temperature increase. Thus, enzyme-like catalysis and antibody-analogue binding are analyzed simultaneously in a bifunctional MIP for the first time (see scheme). Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26737/ U6 - https://doi.org/10.1002/anie.200601796 ER - TY - JOUR A1 - Liu, Songqin A1 - Wollenberger, Ursula A1 - Halamek, Jan A1 - Leupold, Eik A1 - Stöcklein, Walter F. M. A1 - Warsinke, Axel A1 - Scheller, Frieder W. T1 - Affinity interaction betwen phenylboronic acid-carrying self-assembled monolayers and FAD or HRP N2 - A method is provided for the recognition of glycated molecules based on their binding affinities to boronate- carrying monolayers. The affinity interaction of flavin adenine dinucleotide (FAD) and horseradish peroxidase (HRP) with phenylboronic acid monolayers on gold was investigated by using voltammetric and microgravimetric methods. Conjugates of 3-aminopherrylboronic acid and 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces to generate monolayers. FAD is bound to this modified sur-face and recognized by a pair of redox peaks with a formal potential of -0.433 V in a 0.1 m phosphate buffer solution, pH 6.5. Upon addition of a sugar to the buffer, the bound FAD could be replaced, indicating that the binding is reversible. Voltammetric, mass measurements, and photometric activity assays show that the HRP can also be bound to the interface. This binding is reversible, and HRP can be replaced by sorbitol or removed in acidic solution. The effects of pH, incubation time, and concentration of H2O2 were studied by comparing the catalytic reduction of H2O2 in the presence of the electron-donor thionine. The catalytic current of the HRP-loaded electrode was proportional to HRP concentrations in the incubation solution in the range between 5 mu g mL(-1) and 0.4 mg mL(-1) with a linear slope of 3.34 mu A mL mg(-1) and a correlation coefficient of 0.9945 Y1 - 2005 ER -