TY - JOUR A1 - Kröning, Steffen A1 - Scheller, Frieder W. A1 - Wollenberger, Ursula A1 - Lisdat, Fred T1 - Myoglobin-Clay Electrode for Nitric Oxide (NO) Detection in Solution Y1 - 2004 ER - TY - JOUR A1 - Mak, Wing Cheung A1 - Cheung, Kwan Yee A1 - Trau, Dieter A1 - Warsinke, Axel A1 - Scheller, Frieder W. A1 - Renneberg, Reinhard T1 - Electrochemical bioassay utilizing encapsulated electrochemical active microcrystal biolabels N2 - A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a "supernova effect" upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal- generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (SIP) ratio of 10(4)-10(5). Microcrystal biolabels with different antibody surface coverage (1.60-5.05 mg m(-2)) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m(-2) showed a sensitivity of 3.93 nA g(- 1) L-1 with a detection limit of 2.82 g L-1 Y1 - 2005 SN - 0003-2700 ER - TY - JOUR A1 - Liu, Songqin A1 - Wollenberger, Ursula A1 - Halamek, Jan A1 - Leupold, Eik A1 - Stöcklein, Walter F. M. A1 - Warsinke, Axel A1 - Scheller, Frieder W. T1 - Affinity interaction betwen phenylboronic acid-carrying self-assembled monolayers and FAD or HRP N2 - A method is provided for the recognition of glycated molecules based on their binding affinities to boronate- carrying monolayers. The affinity interaction of flavin adenine dinucleotide (FAD) and horseradish peroxidase (HRP) with phenylboronic acid monolayers on gold was investigated by using voltammetric and microgravimetric methods. Conjugates of 3-aminopherrylboronic acid and 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces to generate monolayers. FAD is bound to this modified sur-face and recognized by a pair of redox peaks with a formal potential of -0.433 V in a 0.1 m phosphate buffer solution, pH 6.5. Upon addition of a sugar to the buffer, the bound FAD could be replaced, indicating that the binding is reversible. Voltammetric, mass measurements, and photometric activity assays show that the HRP can also be bound to the interface. This binding is reversible, and HRP can be replaced by sorbitol or removed in acidic solution. The effects of pH, incubation time, and concentration of H2O2 were studied by comparing the catalytic reduction of H2O2 in the presence of the electron-donor thionine. The catalytic current of the HRP-loaded electrode was proportional to HRP concentrations in the incubation solution in the range between 5 mu g mL(-1) and 0.4 mg mL(-1) with a linear slope of 3.34 mu A mL mg(-1) and a correlation coefficient of 0.9945 Y1 - 2005 ER - TY - JOUR A1 - Halamek, Jan A1 - Makower, Alexander A1 - Knösche, Kristina A1 - Skladal, Petr A1 - Scheller, Frieder W. T1 - Piezoelectric affinity sensors for cocaine and cholinesterase inhibitors N2 - We report here the development of piezoelectric affinity sensors for cocaine and cholinesterase inhibitors based on the formation of affinity complexes between an immobilized cocaine derivative and an anti-cocaine antibody or cholinesterase. For both binding reactions benzoylecgonine-1,8-diamino-3,4-dioxaoctane (BZE-DADOO) was immobilized on the surface of the sensor. For immobilization. pre-conjugated BZE-DADOO with 11-mercaptomonoundecanoic acid (MUA) via 2- (5-norbornen-2,3-dicarboximide)-1,1,3,3-tetramethyluronium-tetrafluoro borate (TNTU) allowed the formation of a chemisorbed monolayer on the piezosensor surface. The detection of cocaine was based oil a competitive assay. The change of frequency measured after 300 s of the binding reaction was used as the signal. The maximum binding of the antibody resulted in a frequency decrease of 35 Hz (with an imprecision 3%, n = 3) while the presence of 100 pmol I-1 cocaine decreased the binding by 11%. The limit of detection was consequently below 100 pmol I-1 for cocaine. The total time of one analysis was 15 min. This BZE-DADOO-modified sensor was adapted for the detection of organophosphates. BZE-DADOO - a competitive inhibitor - served as binding element for cholinesterase in a competitive assay. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Bistolas, Nikitas A1 - Wollenberger, Ursula A1 - Jung, Christiane A1 - Scheller, Frieder W. T1 - Cytochrome P450 biosensors : a review N2 - Cytochrome P450 (CYP) is a large family of enzymes containing heme as the active site. Since their discovery and the elucidation of their structure, they have attracted the interest of scientist for many years, particularly due to their catalytic abilities. Since the late 1970s attempts have concentrated on the construction and development of electrochemical sensors. Although sensors based on mediated electron transfer have also been constructed, the direct electron transfer approach has attracted most of the interest. This has enabled the investigation of the electrochemical properties of the various isoforms of CYP. Furthermore, CYP utilized to construct biosensors for the determination of substrates important in environmental monitoring, pharmaceutical industry and clinical practice. (c) 2004 Elsevier B. V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Bistolas, Nikitas A1 - Liu, Songqin A1 - Jänchen, Michael A1 - Katterle, Martin A1 - Wollenberger, Ursula T1 - Thirty years of haemoglobin electrochemistry N2 - Electrochemical investigations of the blood oxygen carrier protein include both mediated and direct electron transfer. The reaction of haemoglobin (Hb) with typical mediators, e.g., ferricyanide, can be quantified by measuring the produced ferrocyanide which is equivalent to the Hb concentration. Immobilization of the mediator within the electrode body allows reagentless electrochemical measuring of Hb. On the other hand, entrapment of the protein within layers of polyclectrolytes, lipids, nanoparticles of clay or gold leads to a fast heterogeneous electron exchange of the partially denatured Hb. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Lisdat, Fred A1 - Wollenberger, Ursula T1 - Application of electrically contacted enzymes for biosensors Y1 - 2005 SN - 3-527- 30690-0 ER - TY - JOUR A1 - Lettau, Kristian A1 - Warsinke, Axel A1 - Katterle, Martin A1 - Danielsson, Bengt A1 - Scheller, Frieder W. T1 - A bifunctional molecularly imprinted polymer (MIP): analysis of binding and catalysis by a thermistor N2 - Binding or catalysis? Both can be distinguished with a molecularly imprinted polymer (MIP) by the different patterns of heat generation. The catalytically active sites, like in the corresponding enzyme, generate a steady-state temperature increase. Thus, enzyme-like catalysis and antibody-analogue binding are analyzed simultaneously in a bifunctional MIP for the first time (see scheme). Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26737/ U6 - https://doi.org/10.1002/anie.200601796 ER - TY - JOUR A1 - Teller, C. A1 - Halamek, Jan A1 - Makower, Alexander A1 - Fournier, Didier A1 - Schulze, H. A1 - Scheller, Frieder W. T1 - A piezoelectric sensor with propidium as a recognition element for cholinesterases N2 - A piezoelectric biosensor has been developed on the basis of the reversible acetylcholinesterase (AChE) inhibitor propidium. The propidium cation was bound to a 11-mercaptoundecanoic acid monolayer on gold-coated quartz crystals. The immobilization was done via activation of carboxyl groups by 1,3-dicyclohexylcarbodiimide (DCC). Different types of cholinesterases (acetyl- and butyryl-ChE) from different origins were tested for their binding ability towards the immobilized propidium. Binding Studies were performed in a flow system, Furthermore, catalytically active and organophosphate-inhibited enzyme were compared re-aiding their binding capability. The binding constants were derived by using an one to one binding model and a refined model also including rebinding effects. It was shown that organophosphorylation of the active site hardly influences the affinity of AChE towards propidium. Furthermore the propidium-based biosensor provides equal sensitivity as compared with piezolelectric sensors with immobilized paraoxon- an active site ligand of AChE. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2006 U6 - https://doi.org/10.1016/j.snb.2005.02.053 ER - TY - JOUR A1 - Halamek, Jan A1 - Teller, Carsten A1 - Zeravik, Jiri A1 - Fournier, Didier A1 - Makower, Alexander A1 - Scheller, Frieder W. T1 - Characterization of binding of cholinesterases to surface immobilized ligands N2 - We summarize here the development of various piezoelectric biosensors utilizing cholinesterase (ChE) as the recognition element. In our work we studied the interaction between cholinesterase and its ligands (propidium, carnitine, benzylgonine-1,8-diamino-3,4-dioxaoctane (BZE-DADOO) and paraoxon). The sensor modification was based on a self-assembled monolayer (SAM) of a thiol compound (11-mercaptoundecanoic acid) on the gold electrode and the subsequent covalent coupling of the cholinesterase ligand to this SAM. The ligand-modified piezoelectric sensors were placed in a flow system to allow the on-line monitoring of cholinesterase binding and the enzymatic activity quantification by amperometry. Cholinesterases from different species-acetylcholinesterase (AChE) from Electrophorus electricus , AChE from Drosophila melanogaster , and butyrylcholinesterase (BChE) of human origin-were tested on the various immobilized ligands. Our research allowed the development of a competitive assay for the detection of organophosphates in river water samples using the BZE-DADOO-modified piezosensor. Another direction of research was pointed on the characterization of the interactions between ChE and its ligands. The kinetic binding constants were derived using a one- to-one binding model Y1 - 2006 UR - http://www.informaworld.com/openurl?genre=journal&issn=0003-2719 U6 - https://doi.org/10.1080/00032710600713107 SN - 0003-2719 ER - TY - JOUR A1 - Halamek, Jan A1 - Teller, Carsten A1 - Makower, Alexander A1 - Fournier, Didier A1 - Scheller, Frieder W. T1 - EQCN-based cholinesterase biosensors N2 - The binding of acetylcholinesterase (AChE) to a propidium-modified piezoelectric quartz crystal and its surface enzymatic activity have been investigated. Propidium binds to a site remote to the active center of AChE - the peripheral anionic site (PAS) - which is located on the rim of the gorge to the active site. The gold electrodes of the quartz crystal were first modified with 11-mercaptoundecanoic acid to which propidium was coupled. AChE binding was monitored by a quartz crystal nanobalance (QCN), followed by amperometric activity evaluation of the AChE loaded on the sensor. Interestingly, the binding is strong but does not inhibit AChE. However, an excess of propidium in solution inhibits the immobilized enzyme. The surface enzymatic activities observed depend on the amount of enzyme and differ according to the type and species, i.e. number of enzyme subunits (Electrophorus electricus tetrameric, Drosophila melanogaster mono- and dimeric form - DmAChE). The operational stability and regeneration, effect of propidium in solution and detection limit for substrate for various AChEs were investigated amperometrically. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/00134686 U6 - https://doi.org/10.1016/j.electacta.2006.03.047 SN - 0013-4686 ER - TY - JOUR A1 - Beissenhirtz, Moritz Karl A1 - Scheller, Frieder W. A1 - Viezzoli, Maria Silvia A1 - Lisdat, Fred T1 - Engineered superoxide dismutase monomers for superoxide biosensor applications N2 - Because of its high reaction rate and specificity, the enzyme superoxide dismutase (SOD) offers great potential for the sensitive quantification of superoxide radicals in electrochemical biosensors. In this work, monomeric mutants of human Cu,Zn-SOD were engineered to contain one or two additional cysteine residues, which could be used to bind the protein to gold surfaces, thus making the use of promotor molecules unnecessary. Six mutants were successfully designed, expressed, and purified. All mutants bound directly to unmodified gold surfaces via the sulfur of the cysteine residues and showed a quasireversible, direct electron transfer to the electrode. Thermodynamic and kinetic parameters of the electron transfer were characterized and showed only slight variations between the individual mutants. For one of the mutants, the interaction with the superoxide radical was studied in more detail. For both partial reactions of the dismutation, an interaction between protein and radical could be shown. In an amperometric biosensorial approach, the SOD-mutant electrode was successfully applied for the detection of superoxide radicals. In the oxidation region, the electrode surpassed the sensitivity of the commonly used cytochrome c electrodes by similar to 1 order of magnitude while not being limited by interferences, but the electrode did not fully reach the sensitivity of dimeric Cu,Zn-SOD immobilized on MPA-modified gold Y1 - 2006 UR - http://pubs.acs.org/journal/ancham U6 - https://doi.org/10.1021/Ac051465g SN - 0003-2700 ER - TY - JOUR A1 - Liu, Songqin A1 - Wollenberger, Ursula A1 - Katterle, Martin A1 - Scheller, Frieder W. T1 - Ferroceneboronic acid-based amperometric biosensor for glycated hemoglobin N2 - An amperometric biosensor for the determination of glycated hemoglobin in human whole blood is proposed. The principle is based on the electrochemical measurement of ferroceneboronic acid (FcBA) that has been specifically bound to the glycated N-terminus. Hemoglobin is immobilized on a zirconium dioxide nanoparticle modified pyrolytic graphite electrode (PGE) in the presence of didodecyldimethylammonium bromide (DDAB). The incubation of this sensor in FcBA solution leads to the formation of an FcBA-modified surface due to the affinity interaction between boronate and the glycated sites of the hemoglobin. The binding of FcBA results in well-defined redox peaks with an E-0' of 0.299 V versus Ag/AgCl (1 M KCl). The square wave voltammetric response of the bound FcBA reflects the amount of glycated hemoglobin at the surface. This signal increases linearily with the degree of glycated hemoglobin from 6.8 to 14.0% of total immobilized hemoglobin. The scheme was applied to the determination of the fraction of glycated hemoglobin in whole blood samples. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/09254005 U6 - https://doi.org/10.1016/j.snb.2005.07.011 SN - 0925-4005 ER - TY - JOUR A1 - Nitsche, Andreas A1 - Kurth, Andreas A1 - Dunkhorst, Anna A1 - Pänke, Oliver A1 - Sielaff, Hendrik A1 - Junge, Wolfgang A1 - Muth, Doreen A1 - Scheller, Frieder W. A1 - Stöcklein, Walter F. M. A1 - Pauli, Georg A1 - Kage, Andreas T1 - One-step selection of vaccinia virus binding DNA-aptamers by MonoLEX Y1 - 2007 UR - http://www.biomedcentral.com/1472-6750/7 U6 - https://doi.org/10.1186/1472-6750-7-48 ER - TY - JOUR A1 - Kapp, Andreas A1 - Beissenhirtz, Moritz Karl A1 - Geyer, F. A1 - Scheller, Frieder W. A1 - Viezzoli, Maria Silvia A1 - Lisdat, Fred T1 - Electrochemical and sensorial behaviour of SOD mutants immobilized on gold electrodes in aqueous / organic solvent mixtures Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26571/ U6 - https://doi.org/10.1002/elan.200603620 SN - 1040-0397 ER -