TY - JOUR AB - In recent decades, significant progress has been made in the treatment of heart diseases, particularly in the field of personalized medicine. Despite the development of genetic tests, phenotyping and risk stratification are performed based on clinical findings and invasive in vivo techniques, such as stimulation conduction mapping techniques and programmed ventricular pacing. Consequently, label-free non-invasive in vitro functional analysis systems are urgently needed for more accurate and effective in vitro risk stratification, model-based therapy planning, and clinical safety profile evaluation of drugs. To overcome these limitations, a novel multilayer high-density microelectrode array (HD-MEA), with an optimized configuration of 512 sensing and 4 pacing electrodes on a sensor area of 100 mm2, was developed for the bioelectronic detection of re-entry arrhythmia patterns. Together with a co-developed front-end, we monitored label-free and in parallel cardiac electrophysiology based on field potential monitoring and mechanical contraction using impedance spectroscopy at the same microelectrode. In proof of principle experiments, human induced pluripotent stem cell (hiPS)-derived cardiomyocytes were cultured on HD-MEAs and used to demonstrate the sensitive quantification of contraction strength modulation by cardioactive drugs such as blebbistatin (IC50 = 4.2 μM), omecamtiv and levosimendan. Strikingly, arrhythmia-typical rotor patterns (re-entry) can be induced by optimized electrical stimulation sequences and detected with high spatial resolution. Therefore, we provide a novel cardiac re-entry analysis system as a promising reference point for diagnostic approaches based on in vitro assays using patient-specific hiPS-derived cardiomyocytes. AU - Schmidt, S.* AU - Li, W.* AU - Schubert, M.* AU - Binnewerg, B.* AU - Prönnecke, C.* AU - Zitzmann, F.D.* AU - Bulst, M.* AU - Wegner, S.* AU - Meier, M. AU - Guan, K.* AU - Jahnke, H.G.* C1 - 70041 C2 - 55375 CY - Oxford Fulfillment Centre The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, Oxon, England TI - Novel high-dense microelectrode array based multimodal bioelectronic monitoring system for cardiac arrhythmia re-entry analysis. JO - Biosens. Bioelectron. VL - 252 PB - Elsevier Advanced Technology PY - 2024 SN - 0956-5663 ER - TY - JOUR AB - Three-dimensional (3D) in vitro cell culture models serve as valuable tools for accurately replicating cellular microenvironments found in vivo. While cell culture technologies are rapidly advancing, the availability of non-invasive, real-time, and label-free analysis methods for 3D cultures remains limited. To meet the demand for higher-throughput drug screening, there is a demanding need for analytical methods that can operate in parallel. Microelectrode systems in combination with microcavity arrays (MCAs), offer the capability of spatially resolved electrochemical impedance analysis and field potential monitoring of 3D cultures. However, the fabrication and handling of small-scale MCAs have been labour-intensive, limiting their broader application. To overcome this challenge, we have established a process for creating MCAs in a standard 96-well plate format using high-precision selective laser etching. In addition, to automate and ensure the accurate placement of 3D cultures on the MCA, we have designed and characterized a plug-in tool using SLA-3D-printing. To characterize our new 96-well plate MCA-based platform, we conducted parallel analyses of human melanoma 3D cultures and monitored the effect of cisplatin in real-time by impedance spectroscopy. In the following we demonstrate the capabilities of the MCA approach by analysing contraction rates of human pluripotent stem cell-derived cardiomyocyte aggregates in response to cardioactive compounds. In summary, our MCA system significantly expands the possibilities for label-free analysis of 3D cell and tissue cultures, offering an order of magnitude higher parallelization capacity than previous devices. This advancement greatly enhances its applicability in real-world settings, such as drug development or clinical diagnostics. AU - Zitzmann, F.D.* AU - Schmidt, S.* AU - Frank, R.* AU - Weigel, W.* AU - Meier, M. AU - Jahnke, H.G.* C1 - 69870 C2 - 55296 CY - Oxford Fulfillment Centre The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, Oxon, England TI - Microcavity well-plate for automated parallel bioelectronic analysis of 3D cell cultures. JO - Biosens. Bioelectron. VL - 250 PB - Elsevier Advanced Technology PY - 2024 SN - 0956-5663 ER - TY - JOUR AB - A new, highly sensitive fluorescence immunoassay for a TIRF (total internal reflection)-based point-of-care testing (POCT) device was developed for the detection of procalcitonin (PCT), a specific and early marker for sepsis and microbial infections. The immunoassay was performed on a bench-top system that fulfilled all the necessary characteristics of a POCT application, including a short measurement time (<9min), no sample pre-treatment requirements and application directly near patients. New rat monoclonal antibodies targeting PCT were screened and characterized. The best combinations of antibodies were then integrated into single-use cartridges, and the reduction of nonspecific binding was achieved by supplying suitable additives. Moreover, human recombinant PCT (hrPCT) for use as a standard was developed in the native form of hPCT in plasma (PCT1-116, PCT3-116). The assay achieves the required sensitivity range in human plasma to allow reliable differentiation between healthy persons and varying stages of infection severity (LOD=0.04ng/mL; LOQ=0.12ng/mL). Furthermore, the developed PCT assay can be applied in whole human blood with an adequate sensitivity (LOD=0.02ng/mL; LOQ=0.09ng/mL). To the best of our knowledge, this is the first diagnostic test for sepsis to use whole blood, which is a crucial requirement for POCT. We were able to detect native PCT in patient samples and showed a good correlation (R(2)=0.988) with the results of the Kryptor(®) device from BRAHMS, a state of the art device for the detection of PCT. AU - Rascher, D. AU - Geerlof, A. AU - Kremmer, E. AU - Krämer, P. AU - Michael, S. AU - Hartmann, A. AU - Rieger, M. C1 - 31075 C2 - 34139 CY - Oxford SP - 251-258 TI - Total Internal Reflection (TIRF)-based quantification of procalcitonin for sepsis diagnosis - a point-of-care testing application. JO - Biosens. Bioelectron. VL - 59 PB - Elsevier Advanced Technology PY - 2014 SN - 0956-5663 ER - TY - JOUR AB - Dengue fever is one of the most neglected tropical diseases and of highest international public health importance, with 50 million cases worldwide every year. Early detection can decrease mortality rates from more than 20% to less than 1% and the relevant early diagnosis analyte is the viral non-structural glycoprotein, NS1. Currently, enzyme linked immunosorbent assay (ELISA) is the method of choice to detect NS1. However, this is a time consuming method, requiring 3-5h, and it is the bottleneck for routine of clinical analysis laboratory in epidemic periods, when hundreds of samples should be tested. Here we describe an easy method combining principles of fluorophore linked immunosorbent assay (FLISA) and enzyme linked immunospotting (ELISPOT). For detection, we used mouse anti-NS1 IgG labeled with fluorescent nanoparticles. The presented procedure needs only 4μL of serum samples and requires 45-60min. The detection limit, 5.2ng/mL, is comparable to ELISA tests. The comparison of 83 samples with a commercial ELISA revealed a sensitivity of 81% and specificity of 88%. The use of fluorescent nanoparticles provides a higher sensitivity than an assay using usual fluorescent dye molecules, besides avoiding bleaching effects. Based on the results, the proposed method provides fast, specific and sensitive results, and proves to be a suitable method for Dengue NS1 detection in impoverished regions or epidemic areas. AU - Linares, E.M. AU - Pannuti, C.S.* AU - Kubota, L.T.* AU - Thalhammer, S. C1 - 11236 C2 - 30569 SP - 180-185 TI - Immunospot assay based on fluorescent nanoparticles for dengue fever detection. JO - Biosens. Bioelectron. VL - 41 IS - 1 PB - Elsevier PY - 2013 SN - 0956-5663 ER - TY - JOUR AB - Soybean is one of the most important crops and plays a key role in the whole food chain production. Soybean crops are very suscetible to the fungus Phakopsora Pachyrhizi, the agent responsible by the Asian soybean rust. The spore of the fungus is easily disseminated by wind with adequate environment, leaf wetness, high humidity and temperatures, the crop can be tottally lost within few days. A high sensitive, specific and easy test is the key for early diagnosing the soybean rust and therefore save the crop. Here we present a paper-based immunosensor for early stage diagnosis of soybean rust that can be performed by unskilled operators on-site. Nitrocellulose membrane was chosen as the substrate to stick the antigen due to its high binding properties. Polyclonal antibodies labeled with fluorescent nanoparticles were employed as the recognizers. An analytical curve with spiked samples shows a linear response range from 0.0032 to 3.2 mu g/mL. This immunosensor presents a very low detection limit of 2.2 ng/mL, which corresponds approximately to 8-12 spores/mL. The paper-based sensor reachs the detection range of ELISA and PCR based test systems, and outranges the available commercial test kits by two order of magnitude. We believe this immunosensor has a great potential as a point-of-care device for the early diagnosis of Asian soybean rust. AU - Santos de Miranda, B.* AU - Linares, E.M. AU - Thalhammer, S. AU - Kubota, L.T.* C1 - 24528 C2 - 31584 SP - 123-128 TI - Development of a disposable and highly sensitive paper-based immunosensor for early diagnosis of Asian soybean rust. JO - Biosens. Bioelectron. VL - 45 IS - 1 PB - Elsevier PY - 2013 SN - 0956-5663 ER - TY - JOUR AB - Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for modification is easy to control and can be optimized and implemented for many carbon materials currently used in microbial fuel cells and other bioelectrochemical systems. AU - Picot, M.* AU - Lapinsonnière, L.* AU - Rothballer, M. AU - Barrière, F.* C1 - 5621 C2 - 29100 CY - Oxfrod, UK SP - 181-188 TI - Graphite anode surface modification with controlled reduction of specific aryl diazonium salts for improved microbial fuel cells power output. JO - Biosens. Bioelectron. VL - 28 IS - 1 PB - Elsevier PY - 2011 SN - 0956-5663 ER - TY - JOUR AB - The proof of principle of a reusable surface plasmon resonance (SPR)-based immunosensor for the monitoring of isoproturon (IPU), a selective and systemic herbicide, is presented. The detecting rat monoclonal anti-isoproturon antibody (mAb IOC 7E1) was reversibly immobilized through the use of a capture mouse anti-rat (kappa-chain) monoclonal antibody (mAb TIB 172), which was covalently immobilized on the sensor chip surface. Such strategy features a controlled binding of the captured detecting antibody as well as facilitates the surface regeneration. The capture of the anti-IPU mAb by the antibody (TIB 172) coated sensor surface could be carried out up to 120 times (immobilization/regeneration cycles) without any evidence of activity loss. With a high test midpoint and a low associated SPR signal, the direct detection format was shown to be unsuitable for the routine analysis of isoproturon. However, the limit of detection (LOD) could be easily enhanced by using a strategy based on a surface competition assay, which improved all immunosensor parameters. Moreover, the sensitivity and working range of the indirect format were found to be dependent on the surface density of the anti-IPU mAb IOC 7E1. As expected for competitive formats, the lowest surface coverage (0.5 ng/mm(2)) allowed a lower detection of the herbicide isoproturon with a calculated LOD of 0.1 microg/l, an IC(50) (50% inhibition) of 5.3+/-0.6 microg/l, and a working range (20-80% inhibition) of 1.3-16.3 microg/l. AU - Gouzy, M.-F. AU - Keß, M. AU - Krämer, P.M. C1 - 1164 C2 - 26067 SP - 1563-1568 TI - A SPR-based immunosensor for the detection of isoproturon. JO - Biosens. Bioelectron. VL - 24 IS - 6 PB - Elsevier Advanced Technology PY - 2009 SN - 0956-5663 ER - TY - JOUR AB - This paper presents a new, versatile, portable miniaturized flow-injection immunosensor which is designed for field analysis. The temperature-controlled field prototype can run for 6 h without external power supply. The bio-recognition element is an analyte-specific antibody immobilized on a gold surface of pyramidal structures inside an exchangeable single-use chip, which hosts also the enzyme-tracer and the sample reservoirs. The competition between the enzyme-tracer and the analyte for the antigen-binding sites of the antibodies yields in the final step a chemiluminescence signal that is inversely proportional to the concentration of analyte in the given range of detection. A proof of principle is shown for nitroaromatics and pesticides. The detection limits (DL; IC20) reached with the field prototype in the laboratory was below 0.1 μg l−1 for 2,4,6-trinitrotoluene (TNT), and about 0.2 μg l−1 for diuron and atrazine, respectively. Important aspects in this development were the design of the competition between analyte and enzyme-tracer, the unspecific signal due to unspecific binding and/or luminescence background signal, and the flow pattern inside the chip. AU - Ciumasu, I.M.* AU - Krämer, P.M. AU - Weber, C.M. AU - Kolb, G.* AU - Tiemann, D.* AU - Windisch, S.* AU - Frese, I.* AU - Kettrup, A. C1 - 2076 C2 - 22729 SP - 354-364 TI - A new, versatile field immunosensor for environmental pollutants. Development and proof of principle with TNT, diuron and atrazine. JO - Biosens. Bioelectron. VL - 21 IS - 2 PY - 2005 SN - 0956-5663 ER -