TY - JOUR A1 - Lisdat, Fred T1 - Coupling biology to electrochemistry—future trends and needs JF - Journal of Solid State Electrochemistry N2 - The coupling of biological entities with electrodes has already quite some history and has reached a status which is not only based on phenomenological descriptions. Nowadays, we are able to effectively couple redox centres within protein molecules to electrochemical transducers. This allows the transduction of a biochemical reaction into an electrode signal with applications mainly in sensing and bioenergetics [1,2,3,4,5,6,7,8]. However, in most cases, this coupling is not direct, and shuttle molecules or side products of the reaction are used. But also for the direct coupling, significant progress has been made, and several enzymes and redox proteins can be addressed directly by electrodes [8,9,10,11,12,13]. The understanding of the functioning of developed systems is, however, in its infancy. Charge and electrostatic interactions have been mostly studied, and for small dipole molecules such as cytochrome c, the situation can be well described [14]. There is a lack of understanding for more complex enzyme molecules which brings a lot of trial and error into research. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13639 SN - 1433-0768 VL - 24 SP - 2125 EP - 2127 PB - Springer Nature ER - TY - JOUR A1 - Göbel, Gero A1 - Talke, Anja A1 - Ahnert, Uwe A1 - Lisdat, Fred T1 - Electrochemical Activity Determination of Catechol-O-methyl Transferase by Selective Dopamine Detection JF - ChemElectroChem N2 - 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. KW - catechol-O-methyl transferase KW - dopamine KW - flow system KW - fluorine-doped tin oxide KW - sensing Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13900 VL - 6 IS - 17 SP - 4533 EP - 4540 PB - Wiley ER - TY - JOUR A1 - Dimitriev, O. P. A1 - Grytsenko, Kostyantyn A1 - Tolmachev, O. I. A1 - Slominskii, Yu L. A1 - Kudinova, M. A. A1 - Schrader, Sigurd T1 - Effect of Concentration on Isomerization of Rhodanine Derivatives of Merocyanine Dyes in Polar Solvents JF - Advances in Physical Chemistry N2 - Rhodanine derivatives of merocyanine dyes with residues of 1,3,3-trimethyl-3H-indole and 3-ethylbenzothiazoline have been found to possess two molecular forms in diluted solutions of polar solvents such as dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidinone. The first molecular form was observed to prevail at low concentrations of the dyes, normally up to 10−5 M. The second one prevails at higher concentrations and is displayed through a new band in the electronic absorption spectrum, which is red-shifted with respect to the absorption band of the first form. No similar effect was found for these dyes by use of nonpolar solvents or upon alkyl-substitution of the molecules at nitrogen atom in the rhodanine moiety. We assign the above two forms to different molecular isomers and the analogous spectral changes were shown to take place by light or heat influence which correspond to a typical isomerization effect for the related merocyanine dyes. It is discussed that the isomer transformation is facilitated by the increased mobility of the proton bonded to the nitrogen atom of the rhodanine moiety in the polar environment and the increased amount of dye-dye collisions. Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-5931 SN - 1687-7993 VL - 2014 ER - TY - JOUR A1 - Zhao, Shuang A1 - Yue, Zhao A1 - Zhu, Dingcheng A1 - Harberts, Jann A1 - Blick, Robert H. A1 - Zierold, Robert A1 - Lisdat, Fred A1 - Parak, Wolfgang J. T1 - Quantum Dot/TiO2 Nanocomposite-Based Photoelectrochemical Sensor for Enhanced H2O2 Detection Applied for Cell Monitoring and Visualization JF - Small N2 - This work exploits the possibility of using CdSe/ZnS quantum dot (QD)-electrodes to monitor the metabolism of living cells based on photoelectrochemical (PEC) measurements. To realize that, the PEC setup is improved with respect to an enhanced photocurrent signal, better stability, and an increased signal-to-noise ratio, but also for a better biocompatibility of the sensor surface on which cells have been grown. To achieve this, a QD-TiO2 heterojunction is introduced with the help of atomic layer deposition (ALD). The heterojunction reduces the charge carrier recombination inside the semiconductor nanoparticles and improves the drift behavior. The PEC performance is carefully analyzed by adjusting the TiO2 thickness and combining this strategy with multilayer immobilizations of QDs. The optimal thickness of this coating is ≈5 nm; here, photocurrent generation can be enhanced significantly (e.g., for a single QD layer electrode by more than one order of magnitude at 0 V vs Ag/AgCl). The resulting optimized electrode is used for hydrogen peroxide (H2O2) sensing with a good sensitivity down to µmolar concentrations, reusability, stability, response rate, and repeatability. Finally, the sensing system is applied to monitor the activity of cells directly grown on top of the electrode surface. KW - biocompatible interface with atomic layer deposition KW - biosensor KW - detection of cellular metabolism KW - light addressable potentiometric sensor KW - photocurrent measurements Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-19642 VL - 20 IS - 45 PB - Wiley ER - TY - JOUR A1 - Anand, Ketan A1 - Schubert, Markus Andreas A1 - Corley-Wiciak, Agnieszka Anna A1 - Spirito, Davide A1 - Corley-Wiciak, Cedric A1 - Klesse, Wolfgang M. A1 - Mai, Andreas A1 - Tillack, Bernd A1 - Yamamoto, Yuji T1 - Lateral Selective SiGe Growth for Local Dislocation-Free SiGe-on-Insulator Virtual Substrate Fabrication JF - ECS Journal of Solid State Science and Technology N2 - Dislocation free local SiGe-on-insulator (SGOI) virtual substrate is fabricated using lateral selective SiGe growth by reduced pressure chemical vapor deposition. The lateral selective SiGe growth is performed around a ∼1.25 μm square Si (001) pillar in a cavity formed by HCl vapor phase etching of Si at 850 °C from side of SiO2/Si mesa structure on buried oxide. Smooth root mean square roughness of SiGe surface of 0.14 nm, which is determined by interface roughness between the sacrificially etched Si and the SiO2 cap, is obtained. Uniform Ge content of ∼40% in the laterally grown SiGe is observed. In the Si pillar, tensile strain of ∼0.65% is found which could be due to thermal expansion difference between SiO2 and Si. In the SiGe, tensile strain of ∼1.4% along 〈010〉 direction, which is higher compared to that along 〈110〉 direction, is observed. The tensile strain is induced from both [110] and [−110] directions. Threading dislocations in the SiGe are located only ∼400 nm from Si pillar and stacking faults are running towards 〈110〉 directions, resulting in the formation of a wide dislocation-free area in SiGe along 〈010〉 due to horizontal aspect ratio trapping. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-17013 VL - 12 PB - Electrochemical Society (ECS); IOP ER - TY - GEN A1 - Frischkorn, Felix A1 - Kreitlow, Horst A1 - Martini, Lothar A1 - Miesner, Jörn A1 - Stark, Bernd A1 - Wernecke, Roland T1 - Holographisches Messverfahren zur dreidimensionalen Analyse von Aerosolen T2 - Wissenschaftliche Beiträge 2/2000 N2 - Die Deutsche Bundesstiftung Umwelt (DBU) fördert seit 1998 in einem Großverbund „Atmosphärische Diagnostik“ die Entwicklung neuer Analysenmesstechniken, die kommerziell nicht verfügbar sind. Unter anderem wird in diesem Rahmen auch ein Projekt zur Entwicklung eines Messsystems zur „Dreidimensionalen Aufnahme von Aerosolverteilungen“ gefördert. Die Leitung dieses Projektes wurde der Technischen Fachhochschule Wildau übertragen. Kooperationspartner sind das Institut für Lasertechnik der Fachhochschule Ostfriesland Emden und die Firma deka Sensor & Technologie Teltow. Ziel des Projektes ist die Entwicklung eines mobilen Messgerätes, das nach einem holographischen Verfahren dreidimensionale Momentaufnahmen der Partikelverteilung in schneller Folge und damit auch Untersuchungen der Partikeldynamik gestattet. Das Projekt findet im Oktober 2000 bei einer Felderprobung des Messsystems auf dem Kleinen Feldberg im Taunus unter rauen Umweltbedingungen im Rahmen des Verbundes „Atmosphärische Diagnostik“ seinen Abschluss. Über die Grundlagen der Entwicklung des Projektes „Dreidimensionale Aufnahme von Aerosolverteilungen“ und das Ergebnis der Arbeiten soll im Folgenden berichtet werden. Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-7060 SN - 0949-8214 VL - 5 IS - 2 SP - 50 EP - 57 ER - TY - GEN A1 - Stoycheva, Vesela A1 - Goering, Harald A1 - Wolff, Dietmar A1 - Herzog, Michael T1 - Bestimmung der Kohäsionsenergie- und Vernetzungsdichte von Polymeren mit Hilfe von Quellungsmessungen T2 - Wissenschaftliche Beiträge 2014 N2 - Bei der Abschätzung der Beständigkeit von Kunststoffen gegenüber niedermolekularen Flüssigkeiten ist die Kohäsionsenergiedichte CED ein wichtiger Parameter auf molekularer Ebene. Die Vernetzungsdichte ν eines polymeren Festkörpers bildet hierbei einen bedeutsamen Kennwert, der darüber hinaus neben der Löslichkeit wichtige Eigenschaften wie thermische Stabilität und Steifigkeit des Materials charakterisiert. Für die experimentelle Bestimmung von CED und ν eignet sich die Untersuchung des Quellverhaltens in unterschiedlichen Lösungsmitteln. Es werden zwei Messmethoden miteinander verglichen und die Ergebnisse unter Berücksichtigung des molekularen Aufbaus von Proben aus Polyurethan (PU) und hochmolekularem – (HMWPE) und ultrahochmolekularem Polyethylen (UHMWPE) diskutiert. Zum Verständnis des Quellverhaltens dieser Polymerproben in niedermolekularen Lösungsmitteln werden neben den Messergebnissen Literaturdaten zu Grunde gelegt. Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-3372 SN - 0949-8214 VL - 18 SP - 77 EP - 84 ER - TY - GEN A1 - Lange, Janine A1 - Messaoudi, Hamza A1 - Das, Susanta Kumar A1 - Grunwald, Rüdiger A1 - Schrader, Sigurd A1 - Frohme, Marcus A1 - Heinrich, Friedhelm T1 - Analyse komplexer biologischer Proben mittels oberflächenverstärkter Ramanspektroskopie (SERS) T2 - Wissenschaftliche Beiträge 2014 N2 - Diese Studie beschäftigt sich mit dem Nachweis biologischer Proben mit Hilfe der Raman-Mikroskopie. Um ausreichende Signalintensitäten auch bei niedrigen Konzentrationen zu erhalten, wurde insbesondere der Effekt der oberflächenverstärkten Raman-Streuung (SERS) näher untersucht. Als Proben dienten DNA aus Hering-Sperma und das Protein Albumin. Zur Verstärkung des Raman-Spektrums wurden zwei unterschiedliche Methoden verwendet. Zum Einen wurden in einem chemischen Reduktionsprozess Nanosilberpartikel hergestellt und den biologischen Proben zugemischt. Zum Anderen wurden mit Hilfe laserangeregter periodischer Oberflächenstrukturierung (LIPSS) erzeugte nanostrukturierte Silberoberflächen als Substrate für die Proben verwendet. Diese Methode wurde bislang nicht für die SERS-Analyse biologischer Proben eingesetzt. Erste hier präsentierte Messungen zeigen, dass beide Verfahren signifikante SERS-Verstärkungen liefern und potentiell leistungsstarke Methoden für die zerstörungsfreie Analyse biologischer Proben darstellen. Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-3300 SN - 0949-8214 VL - 18 SP - 27 EP - 32 ER - TY - JOUR A1 - Zhao, Shuang A1 - Riedel, Marc A1 - Patarroyo, Javier A1 - Bastús, Neus G. A1 - Puntes, Victor A1 - Yue, Zhao A1 - Lisdat, Fred A1 - Parak, Wolfgang J. T1 - Tailoring of the photocatalytic activity of CeO₂ nanoparticles by the presence of plasmonic Ag nanoparticles JF - Nanoscale N2 - The present study investigates basic features of a photoelectrochemical system based on CeO2 nanoparticles fixed on gold electrodes. Since photocurrent generation is limited to the absorption range of the CeO2 in the UV range, the combination with metal nanoparticles has been studied. It can be shown that the combination of silver nanoparticles with the CeO2 can shift the excitation range into the visible light wavelength range. Here a close contact between both components has been found to be essential and thus, hybrid CeO2@Ag nanoparticles have been prepared and analyzed. We have collected arguments that electron transfer occurs between both compositional elements of the hybrid nanoparticles.The photocurrent generation can be rationalized on the basis of an energy diagram underlying the necessity of surface plasmon excitation in the metal nanoparticles, which is also supported by wavelength-dependent photocurrent measurements. However, electrochemical reactions seem to occur at the CeO2 surface and consequently, the catalytic properties of this material can be exploited as exemplified with the photoelectrochemical reduction of hydrogen peroxide. It can be further demonstrated that the layer-by layer technique can be exploited to create a multilayer system on top of a gold electrode which allows the adjustment of the sensitivity of the photoelectrochemical system. Thus, with a 5-layer electrode with hybrid CeO2@Ag nanoparticles submicromolar hydrogen peroxide concentrations can be detected. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16361 VL - 14 SP - 12048 EP - 12059 PB - Royal Society of Chemistry (RSC) ER - TY - GEN A1 - Stieger, Kai Ralf A1 - Feifel, Sven Christian A1 - Lokstein, Heiko A1 - Hejazi, Mahdi A1 - Zouni, Athina A1 - Lisdat, Fred T1 - Biohybride Architekturen für eine effiziente Umwandlung von Licht in elektrische Energie durch Integration von Photosystem I in skalierbare mesoporöse 3D Elektroden T2 - Wissenschaftliche Beiträge 2018 N2 - Die Kombination von fortschrittlichen Materialien und kontrolliertem Oberflächendesign mit komplexen Proteinen aus der natürlichen Photosynthese ist derzeit eines der Hauptthemen bei der Entwicklung von Biohybridsystemen und Biophotovoltaik. In dieser Studie werden transparente makroporöse 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 können beide Proteine in einer annähernden 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. N2 - The combination of advanced materials and a controlled surface design with complex proteins from natural photosynthesis is currently one of the major topics in the development of biohybrid systems and biophotovoltaic devices. In this study, transparent macroporous indium tin oxide (μITO) electrodes are combined with the trimeric supercomplex, Photosystem I (PSI) from the cyanobacterium Thermosynechococcus elongatus, and the small redox protein cytochrome c (cyt c) to create novel and efficient biohybrid photocathodes. With these 3D structures up to 40 μm in size, both proteins can be deposited in a monolayer fashion and electrical communication with the electrode can be established. The generated photocurrent linearly follows the controllable layer thickness of the μITO electrode up to 40 μm, whereby current densities of up to 150 μA cm –2 are obtained. An efficient electrical coupling of the proteins can be demonstrated by the high internal quantum efficiency of 30 %. Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10220 SN - 0949-8214 VL - 22 SP - 17 EP - 24 ER -