@misc{TanneSchaeferKhalidetal.2012, author = {Tanne, Johannes and Sch{\"a}fer, Daniel and Khalid, Waqas and Parak, Wolfgang J. and Lisdat, Fred}, title = {Lichtgesteuerter bioelektrochemischer Sensor basierend auf CdSe/ZnS-Quantum Dots}, series = {Wissenschaftliche Beitr{\"a}ge 2012}, volume = {16}, journal = {Wissenschaftliche Beitr{\"a}ge 2012}, issn = {0949-8214}, doi = {10.15771/0949-8214_2012_1_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-1357}, pages = {15 -- 22}, year = {2012}, abstract = {Diese Studie besch{\"a}ftigt sich mit der Untersuchung der Sauerstoffsensitivit{\"a}t von QD-Elektroden auf Basis von CdSe/ZnS-Nanopartikeln. Das Verhalten des sauerstoffabh{\"a}ngigen Photostroms wurde dabei in Abh{\"a}ngigkeit des pH-Wertes und des Potentials untersucht. Auf Grundlage dieser Sauerstoffabh{\"a}ngigkeit wurde die Enzymaktivit{\"a}t von GOD {\"u}ber Photostrommessungen evaluiert. F{\"u}r die Konstruktion eines photobioelektrochemischen Sensors, der durch Beleuchtung der entsprechenden Elektrodenfl{\"a}che ausgelesen werden kann, wurden Multischichten auf die CdSe/ZnS-modifizierten Elektroden aufgetragen. Die Layer-by-Layer Deposition von GOD mit Hilfe des Polyelektrolyten PAH zeigte, dass eine Sensorkonstruktion m{\"o}glich ist. Die Sensoreigenschaften dieser Elektroden werden drastisch durch die Menge an immobilisiertem Enzym auf der Quantum Dot-Schicht beeinflusst. Durch die Pr{\"a}paration von vier Bilayern [GOD/PAH]4 an CdSe/ ZnS Elektroden kann ein schnell ansprechbarer Sensor f{\"u}r Konzentrationen zwischen 0.1 - 5 mM Glukose hergestellt werden. Dies er{\"o}ffnet neue M{\"o}glichkeiten f{\"u}r die Multianalytdetektion mit nichtstrukturierten Sensorelektroden, lokalisierten Enzymen und r{\"a}umlich aufgel{\"o}ster Auslesung durch Licht.}, language = {de} } @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.2022, author = {Morlock, Sascha and Subramanian, Senthil Kumar and Zouni, Athina and Lisdat, Fred}, title = {Bio-inorganic hybrid structures for direct electron transfer to photosystem I in photobioelectrodes}, series = {Biosensors and Bioelectronics}, volume = {204}, journal = {Biosensors and Bioelectronics}, publisher = {Elsevier}, issn = {1873-4235}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16770}, year = {2022}, abstract = {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.}, 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{KallabisBeyerleinLisdat2024, author = {Kallabis, Conrad and Beyerlein, Peter and Lisdat, Fred}, title = {Quantitative determination of dopamine in the presence of interfering substances supported by machine learning tools}, series = {Bioelectrochemistry}, volume = {157}, journal = {Bioelectrochemistry}, number = {108667}, issn = {1567-5394}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19277}, year = {2024}, abstract = {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.}, language = {en} } @article{GoebelMuellerTalkeetal.2024, author = {G{\"o}bel, Gero and M{\"u}ller, Florian and Talke, Anja and Ahnert, Uwe and Lisdat, Fred}, title = {Qualitative and quantitative protease activity tests based on protein degradation in three-dimensional structures}, series = {Bioelectrochemistry}, volume = {160}, journal = {Bioelectrochemistry}, issn = {1567-5394}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19294}, year = {2024}, abstract = {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.}, 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{LisdatBeissenhirtzSchelleretal.2006, author = {Lisdat, Fred and Beissenhirtz, Moritz K. and Scheller, Frieder W. and Viezzoli, Maria S.}, title = {Cystein-Mutanten der Cu,Zn-Superoxiddismutase und ihre Anwendung in Proteinelektroden f{\"u}r die Detektion von freien Sauerstoffradikalen}, series = {Wissenschaftliche Beitr{\"a}ge 2006}, volume = {11}, journal = {Wissenschaftliche Beitr{\"a}ge 2006}, issn = {0949-8214}, doi = {10.15771/0949-8214_2006_1_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-216}, pages = {7 -- 11}, year = {2006}, abstract = {Das Enzym Superoxiddismutase (SOD) bietet wegen seiner hohen Reaktionsrate und seiner extrem hohen Substratspezifi t{\"a}t große Vorteile f{\"u}r eine Anwendung als Superoxidbiosensor. In dieser Arbeit wurden durch molekularbiologische Methoden Mutanten der humanen Cu,Zn-SOD gewonnen, welche ein oder zwei zus{\"a}tzliche Cystein-Reste enthielten, die eine einfache Immobilisierung des Proteins durch Bindung des Cystein-Schwefels auf Goldelektroden erm{\"o}glichten. Sechs solcher Mutanten wurden entworfen, exprimiert, aufgereinigt und elektrochemisch charakterisiert. Alle Mutanten konnten durch einen einfachen Inkubationsschritt auf Goldelektroden gebunden werden und zeigten ein quasi-reversibles elektrochemisches Ansprechen. F{\"u}r eine Mutante wurde die Anwendung als Superoxidsensor genauer untersucht und f{\"u}r beide Teilreaktionen der Dismutation ein Ansprechen des Sensors auf das Radikal gefunden. Bei Verwendung einer Teilreaktion konnte die Empfindlichkeit herk{\"o}mmlicher Monoschichtsensoren um etwa eine Gr{\"o}ßenordnung {\"u}bertroffen werden.}, language = {de} } @misc{SchubartGoebelLisdat2013, author = {Schubart, Ivo and G{\"o}bel, Gero and Lisdat, Fred}, title = {Direkte Kontaktierung des Enzyms (PQQ)-GDH und Elektroden mit Hilfe von polymermodifizierten Nanor{\"o}hren f{\"u}r die Anwendung in Biobrennstoffzellen}, series = {Wissenschaftliche Beitr{\"a}ge 2013}, volume = {17}, journal = {Wissenschaftliche Beitr{\"a}ge 2013}, issn = {0949-8214}, doi = {10.15771/0949-8214_2013_1_3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-3127}, pages = {17 -- 22}, year = {2013}, abstract = {In dieser Studie pr{\"a}sentieren wir eine Enzymelektrode, bei der ein direkter Elektronentransfer (DET) zwischen der Pyrrolochinolinchinon-abh{\"a}ngigen Glukosedehydrogenase (PQQ)-GDH und einer Elektrode realisiert werden konnte. Hierf{\"u}r wird eine Goldelektrode mit mehrwandigen Kohlenstoffnanor{\"o}hren [engl. multi-walled carbon nanotubes (MWCNT)] modifiziert, anschließend mit einem Copolymer aus Anilinderivaten {\"u}berzogen und dann die (PQQ)-GDH (Acinetobacter calcoaceticus) kovalent immobilisiert. Die gepulste Polymersynthese wird hinsichtlich der Effektivit{\"a}t der bioelektrokatalytischen Umsetzung von Glukose optimiert. Die Glukoseoxidation startet bei einem Potential von -0,1 V vs. Ag/AgCl (1 M KCl) und Stromdichten von bis zu 500 μA/cm² (+0,1 V) k{\"o}nnen erreicht werden. Der Messbereich f{\"u}r Glukose liegt bei 0,1-5 mM (+0,1 V vs. Ag/AgCl). Der dynamische Bereich ist bei h{\"o}herem Potential auf bis zu 100 mM (+0,4 V vs Ag/AgCl) erweitert. Die Elektrode wird als Anode in einer Biobrennstoffzelle (BBZ) mit einer Bilirubinoxidase-modifizierten MWCNT/Gold-Kathode eingesetzt. Beide Elektroden basieren auf einem DET. Das Zellpotential der BBZ betr{\"a}gt 680 ±20 mV und sie erreicht eine maximale Leistungsdichte von 65 μW/cm² (bei einer Zellspannung von 350 mV).}, language = {de} } @misc{BuetowPaenkeKafkaetal.2008, author = {B{\"u}tow, Sandra M. and P{\"a}nke, Oliver and Kafka, Jan and Lisdat, Fred}, title = {Goldchipelektroden zur elektrochemischen DNA-Detektion}, series = {Wissenschaftliche Beitr{\"a}ge 2008}, volume = {13}, journal = {Wissenschaftliche Beitr{\"a}ge 2008}, issn = {0949-8214}, doi = {10.15771/0949-8214_2008_1_4}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-653}, pages = {25 -- 34}, year = {2008}, abstract = {Im folgenden Artikel werden einfache DNA-Sensoren vorgestellt, mit deren Hilfe es durch voltammetrische und impedimetrische Messmethoden m{\"o}glich ist, schnell, sensitiv und kosteng{\"u}nstig Einzelstrang-DNA (ssDNA) nachzuweisen. Beide Messprinzipien lassen neben der spezifischen Detektion auch die Quantifizierung von DNA-Sequenzen sowie den Nachweis von einzelnen Basenfehlpaarungen innerhalb dieser Sequenzen zu. F{\"a}nger- DNA wurde zu diesem Zweck mit dem 5'-Ende auf einer Goldoberfl{\"a}che immobilisiert. Die Hybridisierung mit einem Methylenblau (MB) markierten oder unmarkierten Probenstrang konnte dann mit Hilfe der Differenzpulsvoltammetrie DPV oder der elektrochemischen Impedanzspektroskopie nachgewiesen werden. Die voltammetrische Quantifizierung erfolgte in einem direkten und kompetitiven Ansatz, mit einem Detektionslimit von 30 nM bzw. 3 nM (bei Einsatz von 0,1 μM Kompetitor- DNA). Das Detektionslimit beim impedimetrischen Nachweis lag bei 100 nM DNA. Die hier vorgestellten Sensoren sind zum einen regenerierbar und k{\"o}nnen zum anderen {\"u}ber einen Zeitraum von zwei Monaten gelagert werden.}, language = {de} }