@article{Lisdat2020, author = {Lisdat, Fred}, title = {Coupling biology to electrochemistry—future trends and needs}, series = {Journal of Solid State Electrochemistry}, volume = {24}, journal = {Journal of Solid State Electrochemistry}, publisher = {Springer Nature}, issn = {1433-0768}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13639}, pages = {2125 -- 2127}, year = {2020}, abstract = {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.}, language = {en} } @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}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13900}, pages = {4533 -- 4540}, year = {2019}, 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{DimitrievGrytsenkoTolmachevetal.2014, author = {Dimitriev, O. P. and Grytsenko, Kostyantyn and Tolmachev, O. I. and Slominskii, Yu L. and Kudinova, M. A. and Schrader, Sigurd}, title = {Effect of Concentration on Isomerization of Rhodanine Derivatives of Merocyanine Dyes in Polar Solvents}, series = {Advances in Physical Chemistry}, volume = {2014}, journal = {Advances in Physical Chemistry}, issn = {1687-7993}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5931}, pages = {9}, year = {2014}, abstract = {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.}, language = {en} } @article{ZhaoYueZhuetal.2024, author = {Zhao, Shuang and Yue, Zhao and Zhu, Dingcheng and Harberts, Jann and Blick, Robert H. and Zierold, Robert and Lisdat, Fred and Parak, Wolfgang J.}, title = {Quantum Dot/TiO2 Nanocomposite-Based Photoelectrochemical Sensor for Enhanced H2O2 Detection Applied for Cell Monitoring and Visualization}, series = {Small}, volume = {20}, journal = {Small}, number = {45}, publisher = {Wiley}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19642}, year = {2024}, abstract = {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.}, language = {en} } @article{AnandSchubertCorleyWiciaketal.2023, author = {Anand, Ketan and Schubert, Markus Andreas and Corley-Wiciak, Agnieszka Anna and Spirito, Davide and Corley-Wiciak, Cedric and Klesse, Wolfgang M. and Mai, Andreas and Tillack, Bernd and Yamamoto, Yuji}, title = {Lateral Selective SiGe Growth for Local Dislocation-Free SiGe-on-Insulator Virtual Substrate Fabrication}, series = {ECS Journal of Solid State Science and Technology}, volume = {12}, journal = {ECS Journal of Solid State Science and Technology}, publisher = {Electrochemical Society (ECS); IOP}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-17013}, year = {2023}, abstract = {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.}, language = {en} } @article{ZhaoRiedelPatarroyoetal.2022, author = {Zhao, Shuang and Riedel, Marc and Patarroyo, Javier and Bast{\´u}s, Neus G. and Puntes, Victor and Yue, Zhao and Lisdat, Fred and Parak, Wolfgang J.}, title = {Tailoring of the photocatalytic activity of CeO₂ nanoparticles by the presence of plasmonic Ag nanoparticles}, series = {Nanoscale}, volume = {14}, journal = {Nanoscale}, publisher = {Royal Society of Chemistry (RSC)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16361}, pages = {12048 -- 12059}, year = {2022}, abstract = {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.}, language = {en} }