@article{YarmanNagelGajovicEichelmannetal.2011, author = {Yarman, Aysu and Nagel, Thomas and Gajovic-Eichelmann, Nenad and Fischer, Anna and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Bioelectrocatalysis by Microperoxidase-11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {23}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {3}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {1040-0397}, doi = {10.1002/elan.201000535}, pages = {611 -- 618}, year = {2011}, abstract = {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.}, language = {en} } @article{TadjoungWaffoYesildagCasertaetal.2018, author = {Tadjoung Waffo, Armel Franklin and Yesildag, Cigdem and Caserta, Giorgio and Katz, Sagie and Zebger, Ingo and Lensen, Marga C. and Wollenberger, Ulla and Scheller, Frieder W. and Altintas, Zeynep}, title = {Fully electrochemical MIP sensor for artemisinin}, series = {Sensors and actuators : B, Chemical}, volume = {275}, journal = {Sensors and actuators : B, Chemical}, publisher = {Elsevier}, address = {Lausanne}, issn = {0925-4005}, doi = {10.1016/j.snb.2018.08.018}, pages = {163 -- 173}, year = {2018}, abstract = {This study aims to develop a rapid, sensitive and cost-effective biomimetic electrochemical sensor for artemisinin determination in plant extracts and for pharmacokinetic studies. A novel molecularly imprinted polymer (MIP)based electrochemical sensor was developed by electropolymerization of o-phenylenediamine (o-PD) in the presence of artemisinin on gold wire surface for sensitive detection of artemisinin. The experimental parameters, including selection of functional monomer, polymerization conditions, template extraction after polymerization, influence of pH and buffer were all optimized. Every step of imprinted film synthesis were evaluated by employing voltammetry techniques, surface-enhanced infrared absorption spectroscopy (SEIRAS) and atomic force microscopy (AFM). The specificity was further evaluated by investigating non-specific artemisinin binding on non-imprinted polymer (NIP) surfaces and an imprinting factor of 6.8 was achieved. The artemisinin imprinted polymers using o-PD as functional monomer have provided highly stable and effective binding cavities for artemisinin. Cross-reactivity studies with drug molecules showed that the MIPs are highly specific for artemisinin. The influence of matrix effect was further investigated both in artificial plant matrix and diluted human serum. The results revealed a high affinity of artemisinin-MIP with dissociation constant of 7.3 x 10(-9) M and with a detection limit of 0.01 mu M and 0.02 mu M in buffer and plant matrix, respectively.}, language = {en} } @article{StoeckleinWarsinkeMicheeletal.1997, author = {St{\"o}cklein, Walter F. M. and Warsinke, Axel and Micheel, Burkhard and H{\"o}hne, Wolfgang and Woller, Jochen and Kempter, Gerhard and Scheller, Frieder W.}, title = {Detection of diphenylurea derivatives with biospecific interaction analysis (BIA) : Kinetic investigations}, year = {1997}, language = {en} } @article{StrefferKaatzBaueretal.1998, author = {Streffer, Katrin and Kaatz, Helvi and Bauer, Christian G. and Makower, Alexander and Schulmeister, Thomas and Scheller, Frieder W. and Peter, Martin G. and Wollenberger, Ursula}, title = {Application of a sensitive catechol detector for determination of tyrosinase inhibitors}, year = {1998}, language = {en} } @article{JetzschmannTankJagerszkietal.2019, author = {Jetzschmann, Katharina J. and Tank, Steffen and Jagerszki, Gyula and Gyurcsanyi, Robert E. and Wollenberger, Ulla and Scheller, Frieder W.}, title = {Bio-Electrosynthesis of Vectorially Imprinted Polymer Nanofilms for Cytochrome P450cam}, series = {ChemElectroChem}, volume = {6}, journal = {ChemElectroChem}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2196-0216}, doi = {10.1002/celc.201801851}, pages = {1818 -- 1823}, year = {2019}, abstract = {A new approach for synthesizing a vectorially imprinted polymer (VIP) is presented for the microbial cytochrome P450cam enzyme. A surface attached binding motif of a natural reaction partner of the target protein, putidaredoxin (Pdx), is the anchor to the underlying transducer. The 15 amino acid peptide anchor, which stems from the largest continuous amino acid chain within the binding site of Pdx was modified: (i) internal cysteines were replaced by serines to prevent disulfide bond formation; (ii) 2 ethylene glycol units were attached to the N-terminus as a spacer region; and (iii) an N-terminal cysteine was added to allow the immobilization on the gold electrode surface. Immobilization on GCE was achieved via an N-(1-pyrenyl)maleimide (NPM) cross-linker. In this way oriented immobilization of P450cam was accomplished by binding it to a peptide-modified gold or glassy carbon electrode (GCE) prior to the electrosynthesis of a polymer nanofilm around the immobilized target. This VIP nanofilm enabled reversible oriented docking of P450cam as it is indicated by the catalytic oxygen reduction via direct electron transfer between the enzyme and the underlying electrode. Catalysis of oxygen reduction by P450cam bound to the VIP-modified GCE was used to measure rebinding to the VIP. The mild coupling of an oxidoreductase with the electrode may be appropriate for realizing electrode-driven substrate conversion by instable P450 enzymes without the need of NADPH co-factor.}, language = {en} }