TY - JOUR A1 - Scheller, Frieder W. A1 - Zhang, Xiaorong A1 - Yarman, Aysu A1 - Wollenberger, Ulla A1 - Gyurcsányi, Róbert E. T1 - Molecularly imprinted polymer-based electrochemical sensors for biopolymers JF - Current opinion in electrochemistry N2 - Electrochemical synthesis and signal generation dominate among the almost 1200 articles published annually on protein-imprinted polymers. Such polymers can be easily prepared directly on the electrode surface, and the polymer thickness can be precisely adjusted to the size of the target to enable its free exchange. In this architecture, the molecularly imprinted polymer (MIP) layer represents only one ‘separation plate’; thus, the selectivity does not reach the values of ‘bulk’ measurements. The binding of target proteins can be detected straightforwardly by their modulating effect on the diffusional permeability of a redox marker through the thin MIP films. However, this generates an ‘overall apparent’ signal, which may include nonspecific interactions in the polymer layer and at the electrode surface. Certain targets, such as enzymes or redox active proteins, enables a more specific direct quantification of their binding to MIPs by in situ determination of the enzyme activity or direct electron transfer, respectively. KW - Electropolymerization KW - Direct electron transfer KW - Redox marker KW - Epitope imprinting KW - Biomarker Y1 - 2018 U6 - https://doi.org/10.1016/j.coelec.2018.12.005 SN - 2451-9103 VL - 14 SP - 53 EP - 59 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zeng, Ting A1 - Frasca, Stefano A1 - Rumschöttel, Jens A1 - Koetz, Joachim A1 - Leimkühler, Silke A1 - Wollenberger, Ursula T1 - Role of Conductive Nanoparticles in the Direct Unmediated Bioelectrocatalysis of Immobilized Sulfite Oxidase JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis KW - Direct electron transfer KW - Protein voltammetry KW - Human sulfite oxidase KW - Bioelectrocatalysis KW - Nanoparticles Y1 - 2016 U6 - https://doi.org/10.1002/elan.201600246 SN - 1040-0397 SN - 1521-4109 VL - 28 SP - 2303 EP - 2310 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zeng, Ting A1 - Pankratov, Dmitry A1 - Falk, Magnus A1 - Leimkühler, Silke A1 - Shleev, Sergey A1 - Wollenberger, Ursula T1 - Miniature direct electron transfer based sulphite/oxygen enzymatic fuel cells JF - Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics N2 - A direct electron transfer (DET) based sulphite/oxygen biofuel cell is reported that utilises human sulphite oxidase (hSOx) and Myrothecium verrucaria bilirubin oxidase (MvBOx) and nanostructured gold electrodes. For bioanode construction, the nanostructured gold microelectrodes were further modified with 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) to which polyethylene imine was covalently attached. hSOx was adsorbed onto this chemically modified nanostructured electrode with high surface loading of electroactive enzyme and in presence of sulphite high anodic bioelectrocatalytic currents were generated with an onset potential of 0.05 V vs. NHE. The biocathode contained MyBOx directly adsorbed to the deposited gold nanoparticles for cathodic oxygen reduction starting at 0.71 V vs. NHE. Both enzyme electrodes were integrated to a DET-type biofuel cell. Power densities of 8 and 1 mu W cm(-2) were achieved at 0.15 V and 0.45 V of cell voltages, respectively, with the membrane based biodevices under aerobic conditions. (C) 2014 Elsevier B.V. All rights reserved. KW - Enzymatic fuel cell KW - Microscale electrode KW - Direct electron transfer KW - Sulphite oxidase KW - Bilirubin oxidase Y1 - 2015 U6 - https://doi.org/10.1016/j.bios.2014.10.080 SN - 0956-5663 SN - 1873-4235 VL - 66 SP - 39 EP - 42 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Yarman, Aysu A1 - Nagel, Thomas A1 - Gajovic-Eichelmann, Nenad A1 - Fischer, Anna A1 - Wollenberger, Ursula A1 - Scheller, Frieder W. T1 - Bioelectrocatalysis by Microperoxidase-11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis N2 - We report on the redox behaviour of the microperoxidase-11 (MP-11) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. MP-11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP-11 at high scan rate is between 350+/-50 pmol cm(-2), which reflects a multilayer process. The formal potential (E degrees') of MP-11 in the gold nanoparticles-chitosan film was estimated to be -(267.7+/-2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (k(s)) starts at 1.21 s(-1) and levels off at 6.45 s(-1) in the scan rate range from 0.1 to 2.0 V s(-1). Oxidation and reduction of MP-11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP-11. KW - Microperoxidase KW - Direct electron transfer KW - Nanoparticles KW - Hydrogen peroxide KW - Superoxide KW - Bioelectrocatalysis Y1 - 2011 U6 - https://doi.org/10.1002/elan.201000535 SN - 1040-0397 VL - 23 IS - 3 SP - 611 EP - 618 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Wu, Yunhua A1 - Wollenberger, Ursula A1 - Hofrichter, Martin A1 - Ullrich, Rene A1 - Scheibner, Katrin A1 - Scheller, Frieder W. T1 - Direct electron transfer of Agrocybe aegerita peroxygenase at electrodes modified with chitosan-capped Au nanoparticles and its bioelectrocatalysis to aniline JF - Sensors and actuators : B, Chemical N2 - Three different sizes of chitosan-capped Au nanoparticles were synthesized and were used to incorporate Agrocybe aegerita peroxygenase (AaeAPO) onto the surface of glassy carbon electrode. The direct electron transfer of AaeAPO was achieved in all films. The highest amount of electroactive enzyme and highest electron transfer rate constant k(s) of AaeAPO were obtained in the film with the smallest size of chitosan-capped Au nanoparticles. In anaerobic solutions, quasi-reversible oxidation and reduction are obtained with a formal potential of -0.280V vs. Ag/AgCl 1 M KCl in 100 mM (pH 7.0) PBS at scan rate of 1 V s(-1). Bioelectrocatalytic reduction currents can be obtained with the AaeAPO-modified electrode on addition of hydrogen peroxide. This reaction was suppressed when sodium azide, an inhibitor of AaeAPO, was present. Furthermore, the peroxide-dependent conversion of aniline was characterized and it was found that a polymer product via p-aminophenol is formed. And the AaeAPO biosensor was applied to determine aniline and p-aminophenol. KW - Agrocybe aegerita peroxygenase KW - Au nanoparticles KW - Direct electron transfer KW - Aniline biosensor KW - Bioelectrocatalysis Y1 - 2011 U6 - https://doi.org/10.1016/j.snb.2011.09.090 SN - 0925-4005 VL - 160 IS - 1 SP - 1419 EP - 1426 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Frasca, Stefano A1 - Rojas, Oscar A1 - Salewski, Johannes A1 - Neumann, Bettina A1 - Stiba, Konstanze A1 - Weidinger, Inez M. A1 - Tiersch, Brigitte A1 - Leimkühler, Silke A1 - Koetz, Joachim A1 - Wollenberger, Ursula T1 - Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode JF - Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society N2 - The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10 nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2 s, a linear detection range between 0.5 and 5.4 mu M with a high sensitivity (1.85 nA mu M-1). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples. KW - Direct electron transfer KW - Gold nanoparticle KW - Human sulfite oxidase KW - Ionic liquid KW - Sulfite biosensor Y1 - 2012 U6 - https://doi.org/10.1016/j.bioelechem.2011.11.012 SN - 1567-5394 VL - 87 SP - 33 EP - 41 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Bosserdt, Maria A1 - Gajovic-Eichelman, Nenad A1 - Scheller, Frieder W. T1 - Modulation of direct electron transfer of cytochrome c by use of a molecularly imprinted thin film JF - Analytical & bioanalytical chemistry N2 - We describe the preparation of a molecularly imprinted polymer film (MIP) on top of a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold, where the template cytochrome c (cyt c) participates in direct electron transfer (DET) with the underlying electrode. To enable DET, a non-conductive polymer film is electrodeposited from an aqueous solution of scopoletin and cyt c on to the surface of a gold electrode previously modified with MUA. The electroactive surface concentration of cyt c was 0.5 pmol cm(-2). In the absence of the MUA layer, no cyt c DET was observed and the pseudo-peroxidatic activity of the scopoletin-entrapped protein, assessed via oxidation of Ampliflu red in the presence of hydrogen peroxide, was only 30 % of that for the MIP on MUA. This result indicates that electrostatic adsorption of cyt c by the MUA-SAM substantially increases the surface concentration of cyt c during the electrodeposition step, and is a prerequisite for the productive orientation required for DET. After template removal by treatment with sulfuric acid, rebinding of cyt c to the MUA-MIP-modified electrode occurred with an affinity constant of 100,000 mol(-1) L, a value three times higher than that determined by use of fluorescence titration for the interaction between scopoletin and cyt c in solution. The DET of cyt c in the presence of myoglobin, lysozyme, and bovine serum albumin (BSA) reveals that the MIP layer suppresses the effect of competing proteins. KW - Cytochrome c KW - Molecularly imprinted polymer film KW - Mercaptoundecanoic acid KW - Direct electron transfer KW - Scopoletin (7-hydroxy-6-methoxycoumarin) Y1 - 2013 U6 - https://doi.org/10.1007/s00216-013-7009-8 SN - 1618-2642 VL - 405 IS - 20 SP - 6437 EP - 6444 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - Differently substituted sulfonated polyanilines - the role of polymer compositions in electron transfer with pyrroloquinoline quinone-dependent glucose dehydrogenase JF - Acta biomaterialia N2 - Sulfonated polyanilines have become promising building blocks in the construction of biosensors, and therefore we use here differently substituted polymer forms to investigate the role of their structural composition and properties in achieving a direct electron transfer with the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). To this end, new copolymers containing different ratios of 2-methoxyaniline-5-sulfonic acid (MAS), 3-aminobenzenesulfonic acid (ABS) and 3-aminobenzoic acid (AB) units have been chemically synthesized. All polymers have been studied with respect to their ability to react directly with PQQ-GDH. This interaction has been monitored initially in solution, and subsequently on electrode surfaces. The results show that only copolymers with MAS and aniline units can directly react with PQQ-GDH in solution; the background can be mainly ascribed to the emeraldine salt redox state of the polymer, allowing rather easy reduction. However, when polymers and the enzyme are immobilized on the surface of carbon nanotube-containing electrodes, direct bioelectrocatalysis is also feasible in the case of copolymers composed of ABS/AB and MAS/AB units, existing initially in pernigraniline base form. This verifies that a productive interaction of the enzyme with differently substituted polymers is feasible when the electrode potential can be used to drive the reaction towards the oxidation of the substrate-reduced enzyme. These results clearly demonstrate that enzyme electrodes based on sulfonated polyanilines and direct bioelectrocatalysis can be successfully constructed. KW - Sulfonated polyaniline KW - PQQ-dependent glucose dehydrogenase KW - Direct electron transfer KW - Immobilization KW - Bioelectrocatalysis Y1 - 2013 U6 - https://doi.org/10.1016/j.actbio.2013.06.008 SN - 1742-7061 VL - 9 IS - 9 SP - 8290 EP - 8298 PB - Elsevier CY - Oxford ER -