@article{SternPaulyZydeketal.2016, author = {Stern, Daniel and Pauly, Diana and Zydek, Martin and Miller, Lilija and Piesker, Janett and Laue, Michael and Lisdat, Fred and Dorner, Martin B. and Dorner, Brigitte G. and Nitsche, Andreas}, title = {Development of a Genus-Specific Antigen Capture ELISA for Orthopoxviruses - Target Selection and Optimized Screening}, series = {PLoS ONE}, volume = {11}, journal = {PLoS ONE}, number = {3}, issn = {1932-6203}, doi = {10.1371/journal.pone.0150110}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5830}, pages = {22}, year = {2016}, abstract = {Orthopoxvirus species like cowpox, vaccinia and monkeypox virus cause zoonotic infections in humans worldwide. Infections often occur in rural areas lacking proper diagnostic infrastructure as exemplified by monkeypox, which is endemic in Western and Central Africa. While PCR detection requires demanding equipment and is restricted to genome detection, the evidence of virus particles can complement or replace PCR. Therefore, an easily distributable and manageable antigen capture enzyme-linked immunosorbent assay (ELISA) for the detection of orthopoxviruses was developed to facilitate particle detection. By comparing the virus particle binding properties of polyclonal antibodies developed against surface-exposed attachment or fusion proteins, the surface protein A27 was found to be a well-bound, highly immunogenic and exposed target for antibodies aiming at virus particle detection. Subsequently, eight monoclonal anti-A27 antibodies were generated and characterized by peptide epitope mapping and surface plasmon resonance measurements. All antibodies were found to bind with high affinity to two epitopes at the heparin binding site of A27, toward either the N- or C-terminal of the crucial KKEP-segment of A27. Two antibodies recognizing different epitopes were implemented in an antigen capture ELISA. Validation showed robust detection of virus particles from 11 different orthopoxvirus isolates pathogenic to humans, with the exception of MVA, which is apathogenic to humans. Most orthopoxviruses could be detected reliably for viral loads above 1 × 103 PFU/mL. To our knowledge, this is the first solely monoclonal and therefore reproducible antibody-based antigen capture ELISA able to detect all human pathogenic orthopoxviruses including monkeypox virus, except variola virus which was not included. Therefore, the newly developed antibody-based assay represents important progress towards feasible particle detection of this important genus of viruses.}, language = {en} } @article{GladischSarauliSchaeferetal.2016, author = {Gladisch, Johannes and Sarauli, David and Sch{\"a}fer, Daniel and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {Towards a novel bioelectrocatalytic platform based on "wiring" of pyrroloquinoline quinone-dependent glucose dehydrogenase with an electrospun conductive polymeric fiber architecture}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, issn = {2045-2322}, doi = {10.1038/srep19858}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5846}, pages = {10}, year = {2016}, abstract = {Electrospinning is known as a fabrication technique for electrode architectures that serve as immobilization matrices for biomolecules. The current work demonstrates a novel approach to construct a conductive polymeric platform, capable not only of immobilization, but also of electrical connection of the biomolecule with the electrode. It is produced upon electrospinning from mixtures of three different highly conductive sulfonated polyanilines and polyacrylonitrile on ITO electrodes. The resulting fiber mats are with a well-retained conductivity. After coupling the enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) to polymeric structures and addition of the substrate glucose an efficient bioelectrocatalysis is demonstrated. Depending on the choice of the sulfonated polyanilline mediatorless bioelectrocatalysis starts at low potentials; no large overpotential is needed to drive the reaction. Thus, the electrospun conductive immobilization matrix acts here as a transducing element, representing a promising strategy to use 3D polymeric scaffolds as wiring agents for active enzymes. In addition, the mild and well reproducible fabrication process and the active role of the polymer film in withdrawing electrons from the reduced PQQ-GDH lead to a system with high stability. This could provide access to a larger group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.}, language = {en} } @misc{GladischSarauliSchaeferetal.2016, author = {Gladisch, Johannes and Sarauli, David and Sch{\"a}fer, Daniel and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {Elektrogesponnene Polymerfasern als neuartiges Material f{\"u}r die Bioelektrokatalyse des Enzyms Pyrrolochinolinchinon-abh{\"a}ngige Glucosedehydrogenase}, series = {Wissenschaftliche Beitr{\"a}ge 2016}, volume = {20}, journal = {Wissenschaftliche Beitr{\"a}ge 2016}, issn = {0949-8214}, doi = {10.15771/0949-8214_2016_1_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5293}, pages = {15 -- 21}, year = {2016}, abstract = {Es wurde ein dreidimensionales Polymerfasernetzwerk aufgebaut, charakterisiert und anschließend daran das Enzym Pyrrolochinolinchinon-abh{\"a}ngige Glukosedehydrogenase (PQQ)GDH gebunden. Das Polymerfasernetzwerk wurde durch Elektrospinnen einer Mischung des Polymers Polyacrylnitril und verschiedener leitf{\"a}higer Polymere der Polyanilin-Familie auf Indium-Zinn-Oxid-Elektroden aufgebracht. Die so hergestellten Fasermatten erwiesen sich bei mikroskopischen Untersuchungen gleichf{\"o}rmig pr{\"a}pariert und die Faserdurchmesser bewegten sich im Bereich weniger hundert Nanometer. Das Redoxpaar Kaliumhexacyanoferrat (II/III) zeigte an diesen Polymer-Elektrodenstrukturen eine quasi-reversible Elektrochemie. Bei weitergehenden Untersuchungen an den enzymmodifizierten Fasern ((PQQ)GDH) konnten unter Substratzugabe (Glukose) bioelektrokatalytische Str{\"o}me nachgewiesen werden. Das Fasernetzwerk fungiert hier nicht nur als Immobilisierungsmatrix, sondern als auch als Teil des Signalwandlers.}, language = {de} } @article{GoebelTalkeAhnertetal.2019, author = {G{\"o}bel, Gero and Talke, Anja and Ahnert, Uwe and Lisdat, Fred}, title = {Electrochemical Activity Determination of Catechol-O-methyl Transferase by Selective Dopamine Detection}, series = {ChemElectroChem}, volume = {6}, journal = {ChemElectroChem}, number = {17}, publisher = {Wiley}, doi = {10.1002/celc.201900856}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13900}, pages = {4533 -- 4540}, year = {2019}, abstract = {Abstract For the treatment of Parkinson's disease, as one of the most frequent diseases of the central nervous system, several key enzymes for dopamine metabolism [e. g. catechol-O-methyl transferase (COMT)] are drug targets. For an efficient and long-lasting treatment, the activity of this enzyme should be monitored. In this study, an electrochemical approach using differential pulse voltammetry (DPV) is introduced for the activity determination. The applied electrode material, fluorine-doped tin oxide (FTO), is characterized by a clear discrimination between substrate and product of COMT, a high stability of the dopamine signal during consecutive measurements, and a linear dependency on the dopamine concentration in the range of the maximum reaction rate of COMT. Despite these advantageous results, dopamine detection in the complete activity assay is influenced by each of the added essential assay components, even though none of the added components reveal a current signal at the FTO electrode itself. After adjusting the potential range and the assay composition, these effects can be circumvented. By following the dopamine concentrations during COMT action, it can be shown that the activity of COMT can be detected by using differential pulse voltammetry (DPV) at an FTO electrode and, by analyzing different COMT amounts, quantification can be demonstrated.}, language = {en} } @article{HeinsohnNiedlAnielskietal.2022, author = {Heinsohn, Natascha Katharina and Niedl, Robert Raimund and Anielski, Alexander and Lisdat, Fred and Beta, Carsten}, title = {Electrophoretic µPAD for Purification and Analysis of DNA Samples}, series = {Biosensors}, volume = {12}, journal = {Biosensors}, number = {2}, publisher = {MDPI}, issn = {2079-6374}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15763}, year = {2022}, abstract = {In this work, the fabrication and characterization of a simple, inexpensive, and effective microfluidic paper analytic device (µPAD) for monitoring DNA samples is reported. The glass microfiber-based chip has been fabricated by a new wax-based transfer-printing technique and an electrode printing process. It is capable of moving DNA effectively in a time-dependent fashion. The nucleic acid sample is not damaged by this process and is accumulated in front of the anode, but not directly on the electrode. Thus, further DNA processing is feasible. The system allows the DNA to be purified by separating it from other components in sample mixtures such as proteins. Furthermore, it is demonstrated that DNA can be moved through several layers of the glass fiber material. This proof of concept will provide the basis for the development of rapid test systems, e.g., for the detection of pathogens in water samples.}, language = {en} } @article{MorlockSubramanianZounietal.2023, author = {Morlock, Sascha and Subramanian, Senthil Kumar and Zouni, Athina and Lisdat, Fred}, title = {Closing the green gap of photosystem I with synthetic fluorophores for enhanced photocurrent generation in photobiocathodes}, series = {Chemical Science}, volume = {14}, journal = {Chemical Science}, publisher = {Royal Society of Chemistry (RSC)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-17022}, pages = {1696 -- 1708}, year = {2023}, abstract = {One restriction for biohybrid photovoltaics is the limited conversion of green light by most natural photoactive components. The present study aims to fill the green gap of photosystem I (PSI) with covalently linked fluorophores, ATTO 590 and ATTO 532. Photobiocathodes are prepared by combining a 20 μm thick 3D indium tin oxide (ITO) structure with these constructs to enhance the photocurrent density compared to setups based on native PSI. To this end, two electron transfer mechanisms, with and without a mediator, are studied to evaluate differences in the behavior of the constructs. Wavelength-dependent measurements confirm the influence of the additional fluorophores on the photocurrent. The performance is significantly increased for all modifications compared to native PSI when cytochrome c is present as a redox-mediator. The photocurrent almost doubles from -32.5 to up to -60.9 μA cm-2. For mediator-less photobiocathodes, interestingly, drastic differences appear between the constructs made with various dyes. While the turnover frequency (TOF) is doubled to 10 e-/PSI/s for PSI-ATTO590 on the 3D ITO compared to the reference specimen, the photocurrents are slightly smaller since the PSI-ATTO590 coverage is low. In contrast, the PSI-ATTO532 construct performs exceptionally well. The TOF increases to 31 e-/PSI/s, and a photocurrent of -47.0 μA cm-2 is obtained. This current is a factor of 6 better than the reference made with native PSI in direct electron transfer mode and sets a new record for mediator-free photobioelectrodes combining 3D electrode structures and light-converting biocomponents.}, language = {en} } @article{MorlockSubramanianZounietal.2021, author = {Morlock, Sascha and Subramanian, Senthil Kumar and Zouni, Athina and Lisdat, Fred}, title = {Scalable Three-Dimensional Photobioelectrodes Made of Reduced Graphene Oxide Combined with Photosystem I}, series = {ACS Applied Materials \& Interfaces}, volume = {13}, journal = {ACS Applied Materials \& Interfaces}, number = {9}, publisher = {American Chemical Society (ACS)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16760}, pages = {11237 -- 11246}, year = {2021}, abstract = {Photobioelectrodes represent one of the examples where artificial materials are combined with biological entities to undertake semi-artificial photosynthesis. Here, an approach is described that uses reduced graphene oxide (rGO) as an electrode material. This classical 2D material is used to construct a three-dimensional structure by a template-based approach combined with a simple spin-coating process during preparation. Inspired by this novel material and photosystem I (PSI), a biophotovoltaic electrode is being designed and investigated. Both direct electron transfer to PSI and mediated electron transfer via cytochrome c from horse heart as redox protein can be confirmed. Electrode preparation and protein immobilization have been optimized. The performance can be upscaled by adjusting the thickness of the 3D electrode using different numbers of spin-coating steps during preparation. Thus, photocurrents up to ∼14 μA/cm2 are measured for 12 spin-coated layers of rGO corresponding to a turnover frequency of 30 e- PSI-1 s-1 and external quantum efficiency (EQE) of 0.07\% at a thickness of about 15 μm. Operational stability has been analyzed for several days. Particularly, the performance at low illumination intensities is very promising (1.39 μA/cm2 at 0.1 mW/cm2 and -0.15 V vs Ag/AgCl; EQE 6.8\%).}, language = {en} } @misc{RiedelSchaeferParaketal.2019, author = {Riedel, Marc and Sch{\"a}fer, Daniel and Parak, Wolfgang J. and Ruff, Adrian and Schuhmann, Wolfgang and Lisdat, Fred}, title = {Quantum Dot-modifizierte TiO2-Strukturen f{\"u}r die Licht-gesteuerte Bioelektrokatalyse}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10773}, pages = {11 -- 17}, year = {2019}, abstract = {Die funktionale Kopplung von photoaktiven Nanostrukturen mit Enzymen stellt eine neue Strategie zum Aufbau lichtgesteuerter biohybrider Systeme dar. Hier sind Untersuchungen zusammengefasst, welche die effiziente Kontaktierung der FAD-abh{\"a}ngigen Glukosedehydrogenase (FAD-GDH) mit Hilfe eines Osmium-Redoxpolymers (P Os ) an PbS-Quantum Dots (PbS QDs) zeigen, welche direkt auf dreidimensionalen TiO 2 -Elektrodenstrukturen synthetisiert wurden. Diese biohybriden Strukturen erlauben die Licht-induzierte Oxidation von Glukose. Dazu wird zun{\"a}chst ein Verfahren vorgestellt, bei welchem durch den Aufbau invers-opaler TiO 2 (IO-TiO 2 ) Strukturen hohe Bindungskapazit{\"a}ten f{\"u}r die Integration von QDs, Redoxpolymer und Enzym erreicht werden. In Folge wird gezeigt wie elektrochemische Signalketten durch Licht gesteuert werden k{\"o}nnen, indem Ladungstr{\"a}ger in den QDs unter Beleuchtung erzeugt werden. Diese Aktivierung erm{\"o}glicht dann die Ausbildung einer Elektrontransferkaskade vom Enzym {\"u}ber das Redoxpolymer zu den QDs und final zur IO-TiO 2 -Elektrode. Die resultierenden anodischen Photostr{\"o}me k{\"o}nnen durch das Potential, die Lichtintensit{\"a}t und die Glukosekonzentration moduliert werden. So k{\"o}nnen in Anwesenheit von Glukose Photostr{\"o}me von bis zu 207 μA/cm2 und erste Oxidationssignale bereits bei einem Potential von -540 mV vs Ag/AgCl, 1 M KCl erhalten werden. Dies entspricht einem Potentialgewinn von {\"u}ber 500 mV im Vergleich zu nicht lichtsensitiven Elektroden. Das vorgestellte biohybride System kombiniert Vorteile einer großen Oberfl{\"a}che (durch IO-TiO 2 -Struktur), die effiziente Ladungstr{\"a}gergenerierung und -trennung an der QD/TiO 2 -Schnittstelle sowie die effiziente Kontaktierung von FAD-GDH mit den QDs mit Hilfe eines Redoxpolymers. Die Ergebnisse verdeutlichen das Potential dieser leistungsf{\"a}higen Photobioanode f{\"u}r die Sensorik und die Erzeugung von Energie aus Licht und Glukose.}, language = {de} } @article{ZhaoCarusoDaehneetal.2019, author = {Zhao, Shuang and Caruso, Frank and D{\"a}hne, Lars and Decher, Gero and De Geest, Bruno G. and Fan, Jinchen and Feliu, Neus and Gogotsi, Yury and Hammond, Paula T. and Hersam, Mark C. and Khademhosseini, Ali and Kotov, Nicholas and Leporatti, Stefano and Li, Yan and Lisdat, Fred and Liz-Marz{\´a}n, Luis M. and Moya, Sergio and Mulvaney, Paul and Rogach, Andrey L. and Roy, Sathi and Shchukin, Dmitry G. and Skirtach, Andre G. and Stevens, Molly M. and Sukhorukov, Gleb B. and Weiss, Paul S. and Yue, Zhao and Zhu, Dingcheng and Parak, Wolfgang J.}, title = {The Future of Layer-by-Layer Assembly: A Tribute to ACS Nano Associate Editor Helmuth M{\"o}hwald}, series = {ACS Nano}, volume = {13}, journal = {ACS Nano}, number = {6}, issn = {1936-086X}, doi = {10.1021/acsnano.9b03326}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12356}, pages = {6151 -- 6169}, year = {2019}, abstract = {Layer-by-layer (LbL) assembly is a widely used tool for engineering materials and coatings. In this Perspective, dedicated to the memory of ACS Nano associate editor Prof. Dr. Helmuth M{\"o}hwald, we discuss the developments and applications that are to come in LbL assembly, focusing on coatings, bulk materials, membranes, nanocomposites, and delivery vehicles.}, language = {en} } @article{KoelschHejaziStiegeretal.2018, author = {K{\"o}lsch, Adrian and Hejazi, Mahdi and Stieger, Kai Ralf and Feifel, Sven Christian and Kern, Jan F. and M{\"u}h, Frank and Lisdat, Fred and Lokstein, Heiko and Zouni, Athina}, title = {Insights into the binding behavior of native and non-native cytochromes to photosystem I from Thermosynechococcus elongatus}, series = {Journal of Biological Chemistry}, volume = {293}, journal = {Journal of Biological Chemistry}, number = {23}, issn = {1083-351X}, doi = {10.1074/jbc.RA117.000953}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12780}, pages = {9090 -- 9100}, year = {2018}, abstract = {The binding of photosystem I (PS I) from Thermosynechococcus elongatus to the native cytochrome (cyt) c6 and cyt c from horse heart (cyt cHH) was analyzed by oxygen consumption measurements, isothermal titration calorimetry (ITC), and rigid body docking combined with electrostatic computations of binding energies. Although PS I has a higher affinity for cyt cHH than for cyt c6, the influence of ionic strength and pH on binding is different in the two cases. ITC and theoretical computations revealed the existence of unspecific binding sites for cyt cHH besides one specific binding site close to P700. Binding to PS I was found to be the same for reduced and oxidized cyt cHH. Based on this information, suitable conditions for cocrystallization of cyt cHH with PS I were found, resulting in crystals with a PS I:cyt cHH ratio of 1:1. A crystal structure at 3.4-{\AA} resolution was obtained, but cyt cHH cannot be identified in the electron density map because of unspecific binding sites and/or high flexibility at the specific binding site. Modeling the binding of cyt c6 to PS I revealed a specific binding site where the distance and orientation of cyt c6 relative to P700 are comparable with cyt c2 from purple bacteria relative to P870. This work provides new insights into the binding modes of different cytochromes to PS I, thus facilitating steps toward solving the PS I-cyt c costructure and a more detailed understanding of natural electron transport processes.}, language = {en} } @misc{WettsteinKanoSchaeferetal.2017, author = {Wettstein, Christoph and Kano, Kenji and Sch{\"a}fer, Daniel and Wollenberger, Ulla and Lisdat, Fred}, title = {Die Flavin-abh{\"a}ngige Fruktosedehydrogenase und Cytochrom c: Elektronentransfer und Sensorstrategien}, series = {Wissenschaftliche Beitr{\"a}ge 2017}, volume = {21}, journal = {Wissenschaftliche Beitr{\"a}ge 2017}, issn = {0949-8214}, doi = {10.15771/0949-8214_2017_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9379}, pages = {13 -- 21}, year = {2017}, abstract = {Die hier durchgef{\"u}hrten Untersuchungen erm{\"o}glichen ein besseres Verst{\"a}ndnis der Elektronentransferprozesse zwischen der Flavin-abh{\"a}ngigen Fruktosedehydrogenase (FDH) und dem Redoxprotein Cytochrom c (Cyt c). Dies liefert im Hinblick auf sensorische Anwendungen wichtige Erkenntnisse f{\"u}r vorteilhafte Sensorarchitekturen und deren Messbedingungen. Es wurden zwei unterschiedliche pH-Optima f{\"u}r die Redoxreaktion der beiden Proteine untereinander entdeckt. Die Reaktion wurde im Weiteren mit Elektroden kombiniert und so eine Fruktose-abh{\"a}ngige Stromantwort detektiert. Dar{\"u}ber hinaus konnten definierte dreidimensionale Sensorarchitekturen der beiden Proteine, mit Hilfe von DNA als zus{\"a}tzlichen biologischen Baustein erzeugt und f{\"u}r die Sensorik genutzt werden.}, language = {de} } @misc{StiegerFeifelLoksteinetal.2018, author = {Stieger, Kai Ralf and Feifel, Sven Christian and Lokstein, Heiko and Hejazi, Mahdi and Zouni, Athina and Lisdat, Fred}, title = {Biohybride Architekturen f{\"u}r eine effiziente Umwandlung von Licht in elektrische Energie durch Integration von Photosystem I in skalierbare mesopor{\"o}se 3D Elektroden}, series = {Wissenschaftliche Beitr{\"a}ge 2018}, volume = {22}, journal = {Wissenschaftliche Beitr{\"a}ge 2018}, issn = {0949-8214}, doi = {10.15771/0949-8214_2018_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10220}, pages = {17 -- 24}, year = {2018}, abstract = {Die Kombination von fortschrittlichen Materialien und kontrolliertem Oberfl{\"a}chendesign mit komplexen Proteinen aus der nat{\"u}rlichen Photosynthese ist derzeit eines der Hauptthemen bei der Entwicklung von Biohybridsystemen und Biophotovoltaik. In dieser Studie werden transparente makropor{\"o}se Indium-Zinn-Oxid-(μITO-) Elektroden mit dem trimeren Superkomplex Photosystem I (PSI) aus dem Cyanobakterium Thermosynechococcus elongatus sowie dem kleinen Redoxprotein Cytochrom c (Cyt c) kombiniert, um neuartige und effiziente biohybride Photokathoden herzustellen. Mit diesen bis zu 40 μm hohen 3D-Strukturen k{\"o}nnen beide Proteine in einer ann{\"a}hernden Monolage abgeschieden werden und die elektrische Kommunikation mit der Elektrode kann erzielt werden. Der generierte Photostrom folgt dabei linear der kontrollierbaren Schichtdicke der μITO-Elektrode, wobei Stromdichten von bis zu 150 μA cm -2 erhalten werden. Eine effiziente elektrische Kopplung der Proteine kann durch die hohe interne Quanteneffizienz von 30 \% gezeigt werden.}, language = {de} } @article{GoebelDietzLisdat2009, author = {G{\"o}bel, Gero and Dietz, T. and Lisdat, Fred}, title = {Biosensor based on an oxygen reducing bilirubin oxidase electrode}, series = {Procedia Chemistry}, volume = {1}, journal = {Procedia Chemistry}, number = {1}, issn = {1876-6196}, doi = {10.1016/j.proche.2009.07.068}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6237}, pages = {273 -- 276}, year = {2009}, abstract = {An oxygen reducing electrode made of bilirubin oxidase and multi-walled carbon nanotubes (BOD-MWCNT-Au electrode) is coupled to enzymes catalysing oxygen-consuming reactions such as glucose oxidase (GOD) to result in a membrane-free bienzyme electrode. The feasibility of such a molecularly assembled system stabilized by covalent linkage has been demonstrated. The electrochemical characterisation of the bienzyme electrode reveals sensitivity to the enzyme substrate. The results indicate that the BOD-electrode provides a suitable platform for sensing analytes for which oxidases of high activity are available.}, language = {en} } @article{TanneKracherDietzeletal.2014, author = {Tanne, Johannes and Kracher, Daniel and Dietzel, Birgit and Schulz, Burkhard and Ludwig, Roland and Lisdat, Fred and Scheller, Frieder W. and Bier, Frank Fabian}, title = {Carboxylated or Aminated Polyaniline—Multiwalled Carbon Nanotubes Nanohybrids for Immobilization of Cellobiose Dehydrogenase on Gold Electrodes}, series = {Biosensors}, volume = {4}, journal = {Biosensors}, number = {4}, issn = {2079-6374}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5826}, pages = {370 -- 386}, year = {2014}, abstract = {Polymer-multiwalled carbon nanotube (MWCNT) nanohybrids, which differ in surface charge have been synthesized to study the bioelectrocatalysis of adsorbed cellobiose dehydrogenase (CDH) from Phanerochaete sordida on gold electrodes. To obtain negatively charged nanohybrids, poly(3-amino-4-methoxybenzoic acid-co-aniline) (P(AMB-A)) was covalently linked to the surface of MWCNTs while modification with p-phenylenediamine (PDA) converted the COOH-groups to positively charged amino groups. Fourier transform infrared spectroscopy (FTIR) measurements verified the p-phenylenediamine (PDA) modification of the polymer-CNT nanohybrids. The positively charged nanohybrid MWCNT-P(AMB-A)-PDA promoted direct electron transfer (DET) of CDH to the electrode and bioelectrocatalysis of lactose was observed. Amperometric measurements gave an electrochemical response with KMapp = 8.89 mM and a current density of 410 nA/cm2 (15 mM lactose). The catalytic response was tested at pH 3.5 and 4.5. Interference by ascorbic acid was not observed. The study proves that DET between the MWCNT-P(AMB-A)-PDA nanohybrids and CDH is efficient and allows the sensorial detection of lactose.}, language = {en} } @inproceedings{RiedelGoebelParaketal.2014, author = {Riedel, Marc and G{\"o}bel, Gero and Parak, Wolfgang J. and Lisdat, Fred}, title = {Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15266}, pages = {195 -- 200}, year = {2014}, abstract = {Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.}, language = {en} } @article{BayBuschLisdatetal.2017, author = {Bay, Daniyah H. and Busch, Annika and Lisdat, Fred and Iida, Keisuke and Ikebukuro, Kazunori and Nagasawa, Kazuo and Karube, Isao and Yoshida, Wataru}, title = {Identification of G-quadruplex structures that possess transcriptional regulating functions in the Dele and Cdc6 CpG islands}, series = {BMC Molecular Biology}, volume = {18}, journal = {BMC Molecular Biology}, number = {17}, issn = {1471-2199}, doi = {10.1186/s12867-017-0094-z}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9811}, year = {2017}, abstract = {G-quadruplex is a DNA secondary structure that has been shown to play an important role in biological systems. In a previous study, we identified 1998 G-quadruplex-forming sequences using a mouse CpG islands DNA microarray with a fluorescent-labeled G-quadruplex ligand. Among these putative G-quadruplex-forming sequences, G-quadruplex formation was verified for 10 randomly selected sequences by CD spectroscopy and DMS footprinting analysis. In this study, the biological function of the 10 G-quadruplex-forming sequences in the transcriptional regulation has been analyzed using a reporter assay.}, language = {en} }