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 - Göbel, Gero A1 - Müller, Florian A1 - Talke, Anja A1 - Ahnert, Uwe A1 - Lisdat, Fred T1 - Qualitative and quantitative protease activity tests based on protein degradation in three-dimensional structures JF - Bioelectrochemistry N2 - The pattern of the activity of proteases is related to distinct physiological states of living organisms. Often activity changes of a certain protease can be assigned to a specific disease. Hence, they are useful biomarkers and a simple and fast determination method of their activity could be a valuable tool for the efficient monitoring of numerous diseases. Here, two different methods for the qualitative and quantitative determination of protease activity are demonstrated using the model system of proteinase K. The first test system is based on a protein-modified and colored 3D silica structure that changes color when exposed to the enzyme. This method has also been used for the detection of matrix metallo-protease 2 (MMP2) with gelatine as protease substrate on the plates. The second detection system uses the decrease in the voltammetric signal of a cytochrome c/DNA multilayer electrode after incubation with a protease to quantitatively determine its proteolytic activity. While activities down to 0.15 U/ml can be detected with the first method, the second one provides detection limits of about 0.03 U/ml (for proteinase K.) The functionality of both systems can be demonstrated and ways for further enhancement of sensitivity have been elucidated. KW - multilayer electrode KW - protease activity KW - proteinase K KW - silica gel Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-19294 SN - 1567-5394 VL - 160 ER - TY - JOUR A1 - Kallabis, Conrad A1 - Beyerlein, Peter A1 - Lisdat, Fred T1 - Quantitative determination of dopamine in the presence of interfering substances supported by machine learning tools JF - Bioelectrochemistry N2 - In the field of neuroscience as well as in the clinical setting, the neurotransmitter dopamine (DA) is an analyte which is important for research as well as medical purposes. There are plenty of methods available to measure dopamine quantitatively, with voltammetric ones such as differential pulse voltammetry (DPV) being among the most convenient and simple ones. However, dopamine often occurs, either naturally or because of the requirements of involved enzymatic systems, alongside substances that can influence the signal it produces upon electrochemical conversion. An example for such substances is the magnesium ion, which itself is not electrochemically active in the potential range needed for DA oxidation, but influences the dopamine signal. We have characterized the properties of DPV signals subject to the interaction between DA and Mg2+ and show that, although these properties are changing in a nonlinear fashion when both concentrations are varying, relatively simple linear mathematical models can be used to determine dopamine concentrations quantitatively in the presence of magnesium ions. The focus of this study is thus, the mathematical treatment of experimental data in order to overcome an analytical problem and not the investigation of the chemical background of DA-Mg2+ interaction. KW - dopamine KW - voltammetric detection KW - interference KW - magnesium ion KW - multiple linear regression KW - Bayesian linear regression KW - multivariate calibration models Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-19277 SN - 1567-5394 VL - 157 IS - 108667 ER - TY - JOUR A1 - Morlock, Sascha A1 - Subramanian, Senthil Kumar A1 - Zouni, Athina A1 - Lisdat, Fred T1 - Closing the green gap of photosystem I with synthetic fluorophores for enhanced photocurrent generation in photobiocathodes JF - Chemical Science N2 - 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. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-17022 VL - 14 SP - 1696 EP - 1708 PB - Royal Society of Chemistry (RSC) ER - TY - JOUR A1 - Morlock, Sascha A1 - Subramanian, Senthil Kumar A1 - Zouni, Athina A1 - Lisdat, Fred T1 - Bio-inorganic hybrid structures for direct electron transfer to photosystem I in photobioelectrodes JF - Biosensors and Bioelectronics N2 - Synthetic materials can be combined with biological components in many ways. One example that provides scientists with multiple challenges is a photobioelectrode that converts sunlight into electrons in a biohybrid approach. In the present study several key parameters are evaluated concerning their influence on the direct electron transfer from a 3D indium tin oxide (ITO) electrode material to photosystem I (PSI) as a light-harvesting biomolecule. In contrast to previous investigations, no mediating molecule is added to shuttle the electrons to the luminal side of PSI. Thus, this setup is less complex than foregoing ones. The solution composition drastically influences the interaction of PSI with the ITO surface. Here, the application of higher buffer concentrations and the addition of salts are advantageous, whereas the nature of the buffer ions plays a minor role. The artificial electrode material's thickness is adjustable since a spin-coating procedure is used for preparation. With a 30 μm thick structure and immobilized PSI cathodic photocurrents up to 10.1 μA cm−2 are obtained at 100 mW cm−2 illumination intensity and an applied potential of −0.1V vs. Ag/AgCl. Over a period of three days the photobioelectrodes are illuminated for a total of 90 min and stored between the measurements at ambient temperature. The stability of the setup is noteworthy as still about 90% of the photocurrent is retained. The photocathode described here offers many positive features, including a high onset potential for the photocurrent starting sligthly above the redox potentail of P700, and applicability in a wide pH range from pH 5 to 8. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16770 SN - 1873-4235 VL - 204 PB - Elsevier ER - TY - JOUR A1 - Morlock, Sascha A1 - Subramanian, Senthil Kumar A1 - Zouni, Athina A1 - Lisdat, Fred T1 - Scalable Three-Dimensional Photobioelectrodes Made of Reduced Graphene Oxide Combined with Photosystem I JF - ACS Applied Materials & Interfaces N2 - 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%). KW - biophotovoltaics KW - reduced graphene oxide (rGO) KW - scalable template process KW - spin-coating KW - 3D electrode structure KW - carbon material Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16760 VL - 13 IS - 9 SP - 11237 EP - 11246 PB - American Chemical Society (ACS) 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 - JOUR A1 - Heinsohn, Natascha Katharina A1 - Niedl, Robert Raimund A1 - Anielski, Alexander A1 - Lisdat, Fred A1 - Beta, Carsten T1 - Electrophoretic µPAD for Purification and Analysis of DNA Samples JF - Biosensors N2 - 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. KW - microfluidic paper analytic device (µPAD) KW - patterning glass microfiber KW - fiber-electrophoresis chip KW - DNA KW - imprinted electrodes KW - cross layer chip KW - polymerase chain reaction (PCR) KW - purification Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15763 SN - 2079-6374 VL - 12 IS - 2 PB - MDPI ER - TY - CHAP A1 - Riedel, Marc A1 - Göbel, Gero A1 - Parak, Wolfgang J. A1 - Lisdat, Fred T1 - Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts N2 - 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. KW - quantum dot electrode KW - enzyme sensor KW - signal chain KW - photobioelectrochemistry KW - light adressability Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15266 SP - 195 EP - 200 PB - Society of Photo-Optical Instrumentation Engineers (SPIE) 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 - Riedel, Marc A1 - Höfs, Soraya A1 - Ruff, Adrian A1 - Schuhmann, Wolfgang A1 - Lisdat, Fred T1 - A Tandem Solar Biofuel Cell: Harnessing Energy from Light and Biofuels JF - Angewandte Chemie International Edition N2 - We report on a photobioelectrochemical fuel cell consisting of a glucose‐oxidase‐modified BiFeO3 photobiocathode and a quantum‐dot‐sensitized inverse opal TiO2 photobioanode linked to FAD glucose dehydrogenase via a redox polymer. Both photobioelectrodes are driven by enzymatic glucose conversion. Whereas the photobioanode can collect electrons from sugar oxidation at rather low potential, the photobiocathode shows reduction currents at rather high potential. The electrodes can be arranged in a sandwich‐like manner due to the semi‐transparent nature of BiFeO3, which also guarantees a simultaneous excitation of the photobioanode when illuminated via the cathode side. This tandem cell can generate electricity under illumination and in the presence of glucose and provides an exceptionally high OCV of about 1 V. The developed semi‐artificial system has significant implications for the integration of biocatalysts in photoactive entities for bioenergetic purposes, and it opens up a new path toward generation of electricity from sunlight and (bio)fuels. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13680 SN - 1521-3773 VL - 60 IS - 4 SP - 2078 EP - 2083 PB - Wiley ER - 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 - Kölsch, Adrian A1 - Radon, C. A1 - Golub, M. A1 - Baumert, A. A1 - Bürger, Jörg A1 - Mielke, Thorsten A1 - Lisdat, Fred A1 - Feoktystov, Artem A1 - Pieper, Jörg A1 - Zouni, Athina A1 - Wendler, Petra T1 - Current limits of structural biology: The transient interaction between cytochrome c6 and photosystem I JF - Current Research in Structural Biology N2 - Trimeric photosystem I from the cyanobacterium Thermosynechococcus elongatus (TePSI) is an intrinsic membrane protein, which converts solar energy into electrical energy by oxidizing the soluble redox mediator cytochrome c6 (Cyt c6) and reducing ferredoxin. Here, we use cryo-electron microscopy and small angle neutron scattering (SANS) to characterize the transient binding of Cyt c6 to TePSI. The structure of TePSI cross-linked to Cyt c6 was solved at a resolution of 2.9 Å and shows additional cofactors as well as side chain density for 84% of the peptide chain of subunit PsaK, revealing a hydrophobic, membrane intrinsic loop that enables binding of associated proteins. Due to the poor binding specificity, Cyt c6 could not be localized with certainty in our cryo-EM analysis. SANS measurements confirm that Cyt c6 does not bind to TePSI at protein concentrations comparable to those for cross-linking. However, SANS data indicate a complex formation between TePSI and the non-native mitochondrial cytochrome from horse heart (Cyt cHH). Our study pinpoints the difficulty of identifying very small binding partners (less than 5% of the overall size) in EM structures when binding affinities are poor. We relate our results to well resolved co-structures with known binding affinities and recommend confirmatory methods for complexes with KM values higher than 20 μM. KW - photosystem I KW - cryo-EM KW - Thermosynechococcus elongatus KW - small angle neutron scattering KW - cytochrome c6 KW - electron transfer KW - photo-biotechnology Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13628 SN - 2665-928X VL - 2 SP - 171 EP - 179 ER - TY - JOUR A1 - Kölsch, Adrian A1 - Hejazi, Mahdi A1 - Stieger, Kai Ralf A1 - Feifel, Sven Christian A1 - Kern, Jan F. A1 - Müh, Frank A1 - Lisdat, Fred A1 - Lokstein, Heiko A1 - Zouni, Athina T1 - Insights into the binding behavior of native and non-native cytochromes to photosystem I from Thermosynechococcus elongatus JF - Journal of Biological Chemistry N2 - 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-Å 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. Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-12780 SN - 1083-351X VL - 293 IS - 23 SP - 9090 EP - 9100 ER - TY - JOUR A1 - Zhao, Shuang A1 - Caruso, Frank A1 - Dähne, Lars A1 - Decher, Gero A1 - De Geest, Bruno G. A1 - Fan, Jinchen A1 - Feliu, Neus A1 - Gogotsi, Yury A1 - Hammond, Paula T. A1 - Hersam, Mark C. A1 - Khademhosseini, Ali A1 - Kotov, Nicholas A1 - Leporatti, Stefano A1 - Li, Yan A1 - Lisdat, Fred A1 - Liz-Marzán, Luis M. A1 - Moya, Sergio A1 - Mulvaney, Paul A1 - Rogach, Andrey L. A1 - Roy, Sathi A1 - Shchukin, Dmitry G. A1 - Skirtach, Andre G. A1 - Stevens, Molly M. A1 - Sukhorukov, Gleb B. A1 - Weiss, Paul S. A1 - Yue, Zhao A1 - Zhu, Dingcheng A1 - Parak, Wolfgang J. T1 - The Future of Layer-by-Layer Assembly: A Tribute to ACS Nano Associate Editor Helmuth Möhwald JF - ACS Nano N2 - 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 Möhwald, we discuss the developments and applications that are to come in LbL assembly, focusing on coatings, bulk materials, membranes, nanocomposites, and delivery vehicles. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-12356 SN - 1936-086X VL - 13 IS - 6 SP - 6151 EP - 6169 ER - TY - GEN A1 - Riedel, Marc A1 - Schäfer, Daniel A1 - Parak, Wolfgang J. A1 - Ruff, Adrian A1 - Schuhmann, Wolfgang A1 - Lisdat, Fred T1 - Quantum Dot-modifizierte TiO2-Strukturen für die Licht-gesteuerte Bioelektrokatalyse T2 - Wissenschaftliche Beiträge 2019 N2 - 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-abhängigen 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 zunächst ein Verfahren vorgestellt, bei welchem durch den Aufbau invers-opaler TiO 2 (IO-TiO 2 ) Strukturen hohe Bindungskapazitäten für die Integration von QDs, Redoxpolymer und Enzym erreicht werden. In Folge wird gezeigt wie elektrochemische Signalketten durch Licht gesteuert werden können, indem Ladungsträger in den QDs unter Beleuchtung erzeugt werden. Diese Aktivierung ermöglicht dann die Ausbildung einer Elektrontransferkaskade vom Enzym über das Redoxpolymer zu den QDs und final zur IO-TiO 2 -Elektrode. Die resultierenden anodischen Photoströme können durch das Potential, die Lichtintensität und die Glukosekonzentration moduliert werden. So können in Anwesenheit von Glukose Photoströme 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 über 500 mV im Vergleich zu nicht lichtsensitiven Elektroden. Das vorgestellte biohybride System kombiniert Vorteile einer großen Oberfläche (durch IO-TiO 2 -Struktur), die effiziente Ladungsträgergenerierung 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 leistungsfähigen Photobioanode für die Sensorik und die Erzeugung von Energie aus Licht und Glukose. N2 - The combination of photoactive nanostructures with enzymes represents a new strategy for the construction of light-directed biohybrid systems. The study demonstrates the efficient linkage of FAD-dependent glucose dehydrogenase (FAD-GDH) to PbS quantum dot (QD)-sensitized inverse opal TiO 2 (IO-TiO 2 ) electrodes using an osmium redox polymer (P Os ). How these biohybrid structures can oxidize glucose in a light-directed fashion is highlighted in detail. For this purpose, firstly a method for the construction of IO-TiO 2 electrodes is presented, which gives rise to high binding capacities for the integration of QDs, redox polymer and enzyme. It can be shown how electrochemical signal chains can be controlled with light, resulting in a generation of charge carriers within the QDs. The activation of the electron transfer cascade then allows for an electron transfer from the enzyme via the redox polymer to the QDs and finally to the IO-TiO 2 electrode. The resulting anodic photocurrents can be modulated by potential, light intensity and glucose concentration. In the presence of glucose, photocurrents of up to 207 μA/cm 2 can be generated and first electron withdrawal from the biocatalytic sugar oxidation already proceeds at a potential of -540 mV vs Ag/AgCl (1 M KCl). This corresponds to a potential gain of over 500 mV compared to light-insensitive electrodes. The proposed biohybrid system combines the advantages of a large surface area (IO-TiO 2 ), efficient charge carrier generation (PbS QDs) and separation at the TiO 2 /QDs interface and the efficient linkage of FAD-GDH to the QDs using a redox polymer. This illustrates the potential of this powerful photobioanode for sensing and power supply. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10773 SN - 0949-8214 VL - 23 SP - 11 EP - 17 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 - TY - JOUR A1 - Bay, Daniyah H. A1 - Busch, Annika A1 - Lisdat, Fred A1 - Iida, Keisuke A1 - Ikebukuro, Kazunori A1 - Nagasawa, Kazuo A1 - Karube, Isao A1 - Yoshida, Wataru T1 - Identification of G-quadruplex structures that possess transcriptional regulating functions in the Dele and Cdc6 CpG islands JF - BMC Molecular Biology N2 - 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. KW - Cdc6 KW - Dele KW - G-quadruplex KW - transcriptional regulation KW - 7OTD Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-9811 SN - 1471-2199 VL - 18 IS - 17 ER - TY - GEN A1 - Wettstein, Christoph A1 - Kano, Kenji A1 - Schäfer, Daniel A1 - Wollenberger, Ulla A1 - Lisdat, Fred T1 - Die Flavin-abhängige Fruktosedehydrogenase und Cytochrom c: Elektronentransfer und Sensorstrategien T2 - Wissenschaftliche Beiträge 2017 N2 - Die hier durchgeführten Untersuchungen ermöglichen ein besseres Verständnis der Elektronentransferprozesse zwischen der Flavin-abhängigen Fruktosedehydrogenase (FDH) und dem Redoxprotein Cytochrom c (Cyt c). Dies liefert im Hinblick auf sensorische Anwendungen wichtige Erkenntnisse für vorteilhafte Sensorarchitekturen und deren Messbedingungen. Es wurden zwei unterschiedliche pH-Optima für die Redoxreaktion der beiden Proteine untereinander entdeckt. Die Reaktion wurde im Weiteren mit Elektroden kombiniert und so eine Fruktose-abhängige Stromantwort detektiert. Darüber hinaus konnten definierte dreidimensionale Sensorarchitekturen der beiden Proteine, mit Hilfe von DNA als zusätzlichen biologischen Baustein erzeugt und für die Sensorik genutzt werden. N2 - With regard to sensor application, flavin-dependent fructose dehydrogenase (FDH) and the redox protein cytochrome c (cyt c) were examined for a better understanding of electron transfer (ET) pathways. First, two different pH optima could be determined for the reaction of both proteins. A fructose-dependent signal can be achieved on a cyt c electrode with adsorbed FDH as well as with the enzyme in solution. Furthermore, fructose sensors could be produced using a defined arrangement of cyt c and FDH by the layer-by-layer technique with DNA as a second building block. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-9379 SN - 0949-8214 VL - 21 SP - 13 EP - 21 ER - TY - JOUR A1 - Feifel, Sven Christian A1 - Stieger, Kai Ralf A1 - Kapp, Andreas A1 - Weber, Dennis A1 - Allegrozzi, Marco A1 - Piccioli, Mario A1 - Turano, Paola A1 - Lisdat, Fred T1 - Insights into Interprotein Electron Transfer of Human Cytochrome c Variants Arranged in Multilayer Architectures by Means of an Artificial Silica Nanoparticle Matrix JF - ACS Omega N2 - The redox behavior of proteins plays a crucial part in the design of bioelectronic systems. We have demonstrated several functional systems exploiting the electron exchange properties of the redox protein cytochrome c (cyt c) in combination with enzymes and photoactive proteins. The operation is based on an effective reaction at modified electrodes but also to a large extent on the capability of self-exchange between cyt c molecules in a surface-fixed state. In this context, different variants of human cyt c have been examined here with respect to an altered heterogeneous electron transfer (ET) rate in a monolayer on electrodes as well as an enhanced self-exchange rate while being incorporated in multilayer architectures. For this purpose, mutants of the wild-type (WT) protein have been prepared to change the chemical nature of the surface contact area near the heme edge. The structural integrity of the variants has been verified by NMR and UV–vis measurements. It is shown that the single-point mutations can significantly influence the heterogeneous ET rate at thiol-modified gold electrodes and that electroactive protein/silica nanoparticle multilayers can be constructed with all forms of human cyt c prepared. The kinetic behavior of electron exchange for the mutant proteins in comparison with that of the WT has been found altered in some multilayer arrangements. Higher self-exchange rates have been found for K79A. The results demonstrate that the position of the introduced change in the charge situation of cyt c has a profound influence on the exchange behavior. In addition, the behavior of the cyt c variants in assembled multilayers is found to be rather similar to the situation of cyt c self-exchange in solution verified by NMR. Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-6753 SN - 2470-1343 VL - 1 IS - 6 SP - 1058 EP - 1066 ER -