TY - JOUR A1 - Caserta, Giorgio A1 - Zhang, Xiaorong A1 - Yarman, Aysu A1 - Supala, Eszter A1 - Wollenberger, Ulla A1 - Gyurcsányi, Róbert E. A1 - Zebger, Ingo A1 - Scheller, Frieder W. T1 - Insights in electrosynthesis, target binding, and stability of peptide-imprinted polymer nanofilms JF - Electrochimica acta : the journal of the International Society of Electrochemistry (ISE) N2 - Molecularly imprinted polymer (MIP) nanofilms have been successfully implemented for the recognition of different target molecules: however, the underlying mechanistic details remained vague. This paper provides new insights in the preparation and binding mechanism of electrosynthesized peptide-imprinted polymer nanofilms for selective recognition of the terminal pentapeptides of the beta-chains of human adult hemoglobin, HbA, and its glycated form HbA1c. To differentiate between peptides differing solely in a glucose adduct MIP nanofilms were prepared by a two-step hierarchical electrosynthesis that involves first the chemisorption of a cysteinyl derivative of the pentapeptide followed by electropolymerization of scopoletin. This approach was compared with a random single-step electrosynthesis using scopo-letin/pentapeptide mixtures. Electrochemical monitoring of the peptide binding to the MIP nanofilms by means of redox probe gating revealed a superior affinity of the hierarchical approach with a Kd value of 64.6 nM towards the related target. Changes in the electrosynthesized non-imprinted polymer and MIP nanofilms during chemical, electrochemical template removal and rebinding were substantiated in situ by monitoring the characteristic bands of both target peptides and polymer with surface enhanced infrared absorption spectroscopy. This rational approach led to MIPs with excellent selectivity and provided key mechanistic insights with respect to electrosynthesis, rebinding and stability of the formed MIPs. KW - SEIRA spectroelectrochemistry KW - peptide imprinting KW - electrosynthesis KW - MIP KW - glycated peptide Y1 - 2021 U6 - https://doi.org/10.1016/j.electacta.2021.138236 SN - 0013-4686 SN - 1873-3859 VL - 381 PB - Elsevier CY - New York, NY [u.a.] ER - TY - JOUR A1 - Yarman, Aysu A1 - Kurbanoğlu, Sevinç A1 - Zebger, Ingo A1 - Scheller, Frieder W. T1 - Simple and robust BT - the claims of protein sensing by molecularly imprinted polymers JF - Sensors and actuators : B, Chemical : an international journal devoted to research and development of chemical transducers N2 - A spectrum of 7562 publications on Molecularly Imprinted Polymers (MIPs) has been presented in literature within the last ten years (Scopus, September 7, 2020). Around 10 % of the papers published on MIPs describe the recognition of proteins. The straightforward synthesis of MIPs is a significant advantage as compared with the preparation of enzymes or antibodies. MIPs have been synthesized from only one up to six functional monomers while proteins are made up of 20 natural amino acids. Furthermore, they can be synthesized against structures of low immunogenicity and allow multi-analyte measurements via multi-target synthesis. Electrochemical methods allow simple polymer synthesis, removal of the template and readout. Among the different sensor configurations electrochemical MIP-sensors provide the broadest spectrum of protein analytes. The sensitivity of MIP-sensors is sufficiently high for biomarkers in the sub-nanomolar region, nevertheless the cross-reactivity of highly abundant proteins in human serum is still a challenge. MIPs for proteins offer innovative tools not only for clinical and environmental analysis, but also for bioimaging, therapy and protein engineering. KW - Molecularly imprinted polymer KW - Plastibodies KW - Functional scaffolds KW - Biomimetic sensors KW - Proteins Y1 - 2021 U6 - https://doi.org/10.1016/j.snb.2020.129369 SN - 0925-4005 SN - 1873-3077 VL - 330 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Zhang, Xiaorong A1 - Caserta, Giorgio A1 - Yarman, Aysu A1 - Supala, Eszter A1 - Tadjoung Waffo, Armel Franklin A1 - Wollenberger, Ulla A1 - Gyurcsanyi, Robert E. A1 - Zebger, Ingo A1 - Scheller, Frieder W. T1 - "Out of Pocket" protein binding BT - a dilemma of epitope imprinted polymers revealed for human hemoglobin JF - Chemosensors N2 - The epitope imprinting approach applies exposed peptides as templates to synthesize Molecularly Imprinted Polymers (MIPs) for the recognition of the parent protein. While generally the template protein binding to such MIPs is considered to occur via the epitope-shaped cavities, unspecific interactions of the analyte with non-imprinted polymer as well as the detection method used may add to the complexity and interpretation of the target rebinding. To get new insights on the effects governing the rebinding of analytes, we electrosynthesized two epitope-imprinted polymers using the N-terminal pentapeptide VHLTP-amide of human hemoglobin (HbA) as the template. MIPs were prepared either by single-step electrosynthesis of scopoletin/pentapeptide mixtures or electropolymerization was performed after chemisorption of the cysteine extended VHLTP peptide. Rebinding of the target peptide and the parent HbA protein to the MIP nanofilms was quantified by square wave voltammetry using a redox probe gating, surface enhanced infrared absorption spectroscopy, and atomic force microscopy. While binding of the pentapeptide shows large influence of the amino acid sequence, all three methods revealed strong non-specific binding of HbA to both polyscopoletin-based MIPs with even higher affinities than the target peptides. KW - Molecularly Imprinted Polymers KW - epitope imprinting KW - non-specific KW - binding KW - redox gating KW - SEIRA spectroelectrochemistry Y1 - 2021 U6 - https://doi.org/10.3390/chemosensors9060128 SN - 2227-9040 VL - 9 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Bognár, Zsófia A1 - Supala, Eszter A1 - Yarman, Aysu A1 - Zhang, Xiaorong A1 - Bier, Frank Fabian A1 - Scheller, Frieder W. A1 - Gyurcsanyi, Róbert E. T1 - Peptide epitope-imprinted polymer microarrays for selective protein recognition BT - application for SARS-CoV-2 RBD protein JF - Chemical science / RSC, Royal Society of Chemistry N2 - We introduce a practically generic approach for the generation of epitope-imprinted polymer-based microarrays for protein recognition on surface plasmon resonance imaging (SPRi) chips. The SPRi platform allows the subsequent rapid screening of target binding kinetics in a multiplexed and label-free manner. The versatility of such microarrays, both as synthetic and screening platform, is demonstrated through developing highly affine molecularly imprinted polymers (MIPs) for the recognition of the receptor binding domain (RBD) of SARS-CoV-2 spike protein. A characteristic nonapeptide GFNCYFPLQ from the RBD and other control peptides were microspotted onto gold SPRi chips followed by the electrosynthesis of a polyscopoletin nanofilm to generate in one step MIP arrays. A single chip screening of essential synthesis parameters, including the surface density of the template peptide and its sequence led to MIPs with dissociation constants (K-D) in the lower nanomolar range for RBD, which exceeds the affinity of RBD for its natural target, angiotensin-convertase 2 enzyme. Remarkably, the same MIPs bound SARS-CoV-2 virus like particles with even higher affinity along with excellent discrimination of influenza A (H3N2) virus. While MIPs prepared with a truncated heptapeptide template GFNCYFP showed only a slightly decreased affinity for RBD, a single mismatch in the amino acid sequence of the template, i.e. the substitution of the central cysteine with a serine, fully suppressed the RBD binding. Y1 - 2021 U6 - https://doi.org/10.1039/d1sc04502d SN - 2041-6539 VL - 13 IS - 5 SP - 1263 EP - 1269 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Ozcelikay, Goksu A1 - Kurbanoglu, Sevinc A1 - Yarman, Aysu A1 - Scheller, Frieder W. A1 - Ozkan, Sibel A. T1 - Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin JF - Sensors and actuators : B, Chemical N2 - In this work, a novel electrochemical molecularly imprinted polymer (MIP) sensor for the detection of the lipopeptide antibiotic Daptomycin (DAP) is presented which integrates gold decorated platinum nanoparticles (Au-Pt NPs) into the nanocomposite film. The sensor was prepared by electropolymerization of o-phenylenediamine (o-PD) in the presence of DAP using cyclic voltammetry. Cyclic voltammetry and differential pulse voltammetry were applied to follow the changes in the MIP-layer related to rebinding and removal of the target DAP by using the redox marker [Fe(CN)(6)](3-/4-). Under optimized operational conditions, the MIP/Au-Pt NPs/ GCE nanosensor exhibits a linear response in the range of 1-20 pM towards DAP. The limit of detection and limit of quantification were determined to be 0.161pM +/- 0.012 and 0.489pM +/- 0.012, respectively. The sensitivity towards the antibiotics Vancomycin and Erythromycin and the amino acids glycine and tryptophan was below 7 percent as compared with DAP. Moreover, the nanosensor was also successfully used for the detection of DAP in deproteinated human serum samples. KW - molecularly imprinted polymer KW - Daptomycin KW - platinum nanoparticles KW - gold KW - nanoparticles KW - modified electrodes Y1 - 2020 U6 - https://doi.org/10.1016/j.snb.2020.128285 SN - 0925-4005 VL - 320 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Scheller, Frieder W. A1 - Schmid, Rolf T1 - A tribute to Isao Karube (1942-2020) and his influence on sensor science JF - Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry, Analusis and Quimica analitica KW - Karube KW - Japan KW - biosensors KW - lifetime achievements Y1 - 2020 U6 - https://doi.org/10.1007/s00216-020-02946-5 SN - 1618-2642 SN - 1618-2650 VL - 412 IS - 28 SP - 7709 EP - 7711 PB - Springer CY - Berlin ER - TY - JOUR A1 - Yarman, Aysu A1 - Scheller, Frieder W. T1 - How reliable is the electrochemical readout of MIP sensors? JF - Sensors N2 - Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration. KW - molecularly imprinted polymers KW - electropolymerization KW - direct electron KW - transfer KW - catalysis KW - redox marker KW - gate effect Y1 - 2020 U6 - https://doi.org/10.3390/s20092677 SN - 1424-8220 VL - 20 IS - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Riedel, M. A1 - Sabir, N. A1 - Scheller, Frieder W. A1 - Parak, Wolfgang J. A1 - Lisdat, Fred T1 - Connecting quantum dots with enzymes BT - mediator-based approaches for the light-directed read-out of glucose and fructose oxidation JF - Nanoscale N2 - The combination of the biocatalytic features of enzymes with the unique physical properties of nanoparticles in a biohybrid system provides a promising approach for the development of advanced bioelectrocatalytic devices. This study describes the construction of photoelectrochemical signal chains based on CdSe/ZnS quantum dot (QD) modified gold electrodes as light switchable elements, and low molecular weight redox molecules for the combination with different biocatalysts. Photoelectrochemical and photoluminescence experiments verify that electron transfer can be achieved between the redox molecules hexacyanoferrate and ferrocene, and the QDs under illumination. Since for both redox mediators a concentration dependent photocurrent change has been found, light switchable enzymatic signal chains are built up with fructose dehydrogenase (FDH) and pyrroloquinoline quinone-dependent glucose dehydrogenase ((PQQ) GDH) for the detection of sugars. After immobilization of the enzymes at the QD electrode the biocatalytic oxidation of the substrates can be followed by conversion of the redox mediator in solution and subsequent detection at the QD electrode. Furthermore, (PQQ) GDH has been assembled together with ferrocenecarboxylic acid on top of the QD electrode for the construction of a funtional biohybrid architecture, showing that electron transfer can be realized from the enzyme over the redox mediator to the QDs and subsequently to the electrode in a completely immobilized fashion. The results obtained here do not only provide the basis for light-switchable biosensing and bioelectrocatalytic applications, but may also open the way for self-driven point-of-care systems by combination with solar cell approaches (power generation at the QD electrode by enzymatic substrate consumption). Y1 - 2017 U6 - https://doi.org/10.1039/c7nr00091j SN - 2040-3364 SN - 2040-3372 VL - 9 SP - 2814 EP - 2823 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Yarman, Aysu A1 - Jetzschmann, Katharina J. A1 - Neumann, Bettina A1 - Zhang, Xiaorong A1 - Wollenberger, Ulla A1 - Cordin, Aude A1 - Haupt, Karsten A1 - Scheller, Frieder W. T1 - Enzymes as Tools in MIP-Sensors JF - Chemosensors N2 - Molecularly imprinted polymers (MIPs) have the potential to complement antibodies in bioanalysis, are more stable under harsh conditions, and are potentially cheaper to produce. However, the affinity and especially the selectivity of MIPs are in general lower than those of their biological pendants. Enzymes are useful tools for the preparation of MIPs for both low and high-molecular weight targets: As a green alternative to the well-established methods of chemical polymerization, enzyme-initiated polymerization has been introduced and the removal of protein templates by proteases has been successfully applied. Furthermore, MIPs have been coupled with enzymes in order to enhance the analytical performance of biomimetic sensors: Enzymes have been used in MIP-sensors as tracers for the generation and amplification of the measuring signal. In addition, enzymatic pretreatment of an analyte can extend the analyte spectrum and eliminate interferences. KW - enzymatic MIP synthesis KW - template digestion KW - enzyme tracer KW - enzymatic analyte conversion KW - molecularly imprinted polymers Y1 - 2017 U6 - https://doi.org/10.3390/chemosensors5020011 SN - 2227-9040 VL - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Yarman, Aysu A1 - Kurbanoglu, Sevinc A1 - Jetzschmann, Katharina J. A1 - Ozkan, Sibel A. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. T1 - Electrochemical MIP-Sensors for Drugs JF - Current Medicinal Chemistry N2 - In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano-up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts. KW - Biomimetic sensors KW - molecularly imprinted polymers KW - drug sensors KW - drug imprinting KW - electropolymerization KW - electrochemical sensors Y1 - 2018 U6 - https://doi.org/10.2174/0929867324666171005103712 SN - 0929-8673 SN - 1875-533X VL - 25 IS - 33 SP - 4007 EP - 4019 PB - Bentham Science Publishers LTD CY - Sharjah ER - TY - JOUR A1 - Jetzschmann, Katharina J. A1 - Yarman, Aysu A1 - Rustam, L. A1 - Kielb, P. A1 - Urlacher, V. B. A1 - Fischer, A. A1 - Weidinger, I. M. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. T1 - Molecular LEGO by domain-imprinting of cytochrome P450 BM3 JF - Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces N2 - Hypothesis: Electrosynthesis of the MIP nano-film after binding of the separated domains or holocytochrome BM3 via an engineered anchor should result in domain-specific cavities in the polymer layer. Experiments: Both the two domains and the holo P450 BM3 have been bound prior polymer deposition via a N-terminal engineered his6-anchor to the electrode surface. Each step of MIP preparation was characterized by cyclic voltammetry of the redox-marker ferricyanide. Rebinding after template removal was evaluated by quantifying the suppression of the diffusive permeability of the signal for ferricyanide and by the NADH-dependent reduction of cytochrome c by the reductase domain (BMR). Findings: The working hypothesis is verified by the discrimination of the two domains by the respective MIPs: The holoenzyme P450 BM3 was ca. 5.5 times more effectively recognized by the film imprinted with the oxidase domain (BMO) as compared to the BMR-MIP or the non-imprinted polymer (NIP). Obviously, a cavity is formed during the imprinting process around the hiss-tag-anchored BMR which cannot accommodate the broader BMO or the P450 BM3. The affinity of the MIP towards P450 BM3 is comparable with that to the monomer in solution. The hiss-tagged P450 BM3 binds (30 percent) stronger which shows the additive effect of the interaction with the MIP and the binding to the electrode. KW - Molecularly imprinted polymers KW - Protein imprinting KW - Electropolymerization KW - Cytochrome P450 Y1 - 2018 U6 - https://doi.org/10.1016/j.colsurfb.2018.01.047 SN - 0927-7765 SN - 1873-4367 VL - 164 SP - 240 EP - 246 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zhang, Xiaorong A1 - Yarman, Aysu A1 - Erdossy, Julia A1 - Katz, Sagie A1 - Zebger, Ingo A1 - Jetzschmann, Katharina J. A1 - Altintas, Zeynep A1 - Wollenberger, Ulla A1 - Gyurcsanyi, Robert E. A1 - Scheller, Frieder W. T1 - Electrosynthesized MIPs for transferrin BT - Plastibodies or nano-filters? JF - Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics N2 - Molecularly imprinted polymer (MP) nanofilrns for transferrin (Trf) have been synthesized on gold surfaces by electro-polymerizing the functional monomer scopoletin in the presence of the protein target or around pre-adsorbed Trf. As determined by atomic force microscopy (AFM) the film thickness was comparable with the molecular dimension of the target. The target (re)binding properties of the electro-synthesized MIP films was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV) through the target-binding induced permeability changes of the MIP nanofilms to the ferricyanide redox marker, as well as by surface plasmon resonance (SPR) and surface enhanced infrared absorption spectroscopy (SEIRAS) of the immobilized protein molecules. For Trf a linear concentration dependence in the lower micromolar range and an imprinting factor of similar to 5 was obtained by SWV and SPR. Furthermore, non-target proteins including the iron-free apo-Trf were discriminated by pronounced size and shape specificity. Whilst it is generally assumed that the rebinding of the target or of cross-reacting proteins exclusively takes place at the polymer here we considered also the interaction of the protein molecules with the underlying gold transducers. We demonstrate by SWV that adsorption of proteins suppresses the signal of the redox marker even at the bare gold surface and by SEIRAS that the treatment of the MIP with proteinase K or NaOH only partially removes the target protein. Therefore, we conclude that when interpreting binding of proteins to directly MIP-covered gold electrodes the interactions between the protein and the gold surface should also be considered. KW - Molecularly imprinted polymer KW - Scopoletin KW - Transferrin KW - Protein adsorption KW - Redox marker Y1 - 2018 U6 - https://doi.org/10.1016/j.bios.2018.01.011 SN - 0956-5663 SN - 1873-4235 VL - 105 SP - 29 EP - 35 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Neumann, Bettina A1 - Götz, Robert A1 - Wrzolek, Pierre A1 - Scheller, Frieder W. A1 - Weidinger, Inez M. A1 - Schwalbe, Matthias A1 - Wollenberger, Ulla T1 - Enhancement of the Electrocatalytic Activity of Thienyl-Substituted Iron Porphyrin Electropolymers by a Hangman Effect JF - ChemCatChem : heterogeneous & homogeneous & bio- & nano-catalysis ; a journal of ChemPubSoc Europe N2 - The thiophene-modified iron porphyrin FeT3ThP and the respective iron Hangman porphyrin FeH3ThP, incorporating a carboxylic acid hanging group in the second coordination sphere of the iron center, were electropolymerized on glassy carbon electrodes using 3,4-ethylenedioxythiophene (EDOT) as co-monomer. Scanning electron microscopy images and Resonance Raman spectra demonstrated incorporation of the porphyrin monomers into a fibrous polymer network. Porphyrin/polyEDOT films catalyzed the reduction of molecular oxygen in a four-electron reaction to water with onset potentials as high as +0.14V vs. Ag/AgCl in an aqueous solution of pH7. Further, FeT3ThP/polyEDOT films showed electrocatalytic activity towards reduction of hydrogen peroxide at highly positive potentials, which was significantly enhanced by introduction of the carboxylic acid hanging group in FeH3ThP. The second coordination sphere residue promotes formation of a highly oxidizing reaction intermediate, presumably via advantageous proton supply, as observed for peroxidases and catalases making FeH3ThP/polyEDOT films efficient mimics of heme enzymes. KW - activation of oxygen species KW - electro-polymerization KW - Hangman porphyrin KW - heterogeneous catalysis KW - immobilization Y1 - 2018 U6 - https://doi.org/10.1002/cctc.201800934 SN - 1867-3880 SN - 1867-3899 VL - 10 IS - 19 SP - 4353 EP - 4361 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tadjoung Waffo, Armel Franklin A1 - Yesildag, Cigdem A1 - Caserta, Giorgio A1 - Katz, Sagie A1 - Zebger, Ingo A1 - Lensen, Marga C. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. A1 - Altintas, Zeynep T1 - Fully electrochemical MIP sensor for artemisinin JF - Sensors and actuators : B, Chemical N2 - 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. KW - Electro-synthesized molecularly imprinted polymer KW - o-Phenylenediamine KW - Artemisinin KW - Antimalarial drug detection KW - Electrochemical sensor Y1 - 2018 U6 - https://doi.org/10.1016/j.snb.2018.08.018 SN - 0925-4005 VL - 275 SP - 163 EP - 173 PB - Elsevier CY - Lausanne ER - TY - GEN A1 - Ozcelikay, Goksu A1 - Kurbanoglu, Sevinc A1 - Zhang, Xiaorong A1 - Söz, Çağla Kosak A1 - Wollenberger, Ulla A1 - Ozkan, Sibel A. A1 - Yarman, Aysu A1 - Scheller, Frieder W. T1 - Electrochemical MIP Sensor for Butyrylcholinesterase T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Molecularly imprinted polymers (MIPs) mimic the binding sites of antibodies by substituting the amino acid-scaffold of proteins by synthetic polymers. In this work, the first MIP for the recognition of the diagnostically relevant enzyme butyrylcholinesterase (BuChE) is presented. The MIP was prepared using electropolymerization of the functional monomer o-phenylenediamine and was deposited as a thin film on a glassy carbon electrode by oxidative potentiodynamic polymerization. Rebinding and removal of the template were detected by cyclic voltammetry using ferricyanide as a redox marker. Furthermore, the enzymatic activity of BuChE rebound to the MIP was measured via the anodic oxidation of thiocholine, the reaction product of butyrylthiocholine. The response was linear between 50 pM and 2 nM concentrations of BuChE with a detection limit of 14.7 pM. In addition to the high sensitivity for BuChE, the sensor responded towards pseudo-irreversible inhibitors in the lower mM range. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1138 KW - molecularly imprinted polymers KW - biomimetic sensors KW - butyrylcholinesterase KW - o-phenylenediamine KW - rivastigmine Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-501854 SN - 1866-8372 IS - 1138 ER - TY - JOUR A1 - Jetzschmann, Katharina J. A1 - Tank, Steffen A1 - Jagerszki, Gyula A1 - Gyurcsanyi, Robert E. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. T1 - Bio-Electrosynthesis of Vectorially Imprinted Polymer Nanofilms for Cytochrome P450cam JF - ChemElectroChem N2 - 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. KW - cytochrome P450 KW - direct electron transfer KW - electropolymerization KW - molecularly imprinted polymers KW - protein imprinting Y1 - 2019 U6 - https://doi.org/10.1002/celc.201801851 SN - 2196-0216 VL - 6 IS - 6 SP - 1818 EP - 1823 PB - Wiley-VCH CY - Weinheim ER - 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 - Altintas, Zeynep A1 - Takiden, Aref A1 - Utesch, Tillmann A1 - Mroginski, Maria A. A1 - Schmid, Bianca A1 - Scheller, Frieder W. A1 - Süssmuth, Roderich D. T1 - Integrated approaches toward high-affinity artificial protein binders obtained via computationally simulated epitopes for protein recognition JF - Advanced functional materials N2 - Widely used diagnostic tools make use of antibodies recognizing targeted molecules, but additional techniques are required in order to alleviate the disadvantages of antibodies. Herein, molecular dynamic calculations are performed for the design of high affinity artificial protein binding surfaces for the recognition of neuron specific enolase (NSE), a known cancer biomarker. Computational simulations are employed to identify particularly stabile secondary structure elements. These epitopes are used for the subsequent molecular imprinting, where surface imprinting approach is applied. The molecular imprints generated with the calculated epitopes of greater stability (Cys-Ep1) show better binding properties than those of lower stability (Cys-Ep5). The average binding strength of imprints created with stabile epitopes is found to be around twofold and fourfold higher for the NSE derived peptide and NSE protein, respectively. The recognition of NSE is investigated in a wide concentration range, where high sensitivity (limit of detection (LOD) = 0.5 ng mL(-1)) and affinity (dissociation constant (K-d) = 5.3 x 10(-11)m) are achieved using Cys-Ep1 imprints reflecting the stable structure of the template molecules. This integrated approach employing stability calculations for the identification of stabile epitopes is expected to have a major impact on the future development of high affinity protein capturing binders. KW - artificial protein binders KW - cancer markers KW - computationally simulated epitopes KW - molecular imprinting KW - protein recognition Y1 - 2019 U6 - https://doi.org/10.1002/adfm.201807332 SN - 1616-301X SN - 1616-3028 VL - 29 IS - 15 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Yarman, Aysu A1 - Jetzschmann, Katharina J. A1 - Neumann, Bettina A1 - Zhang, Xiaorong A1 - Wollenberger, Ulla A1 - Cordin, Aude A1 - Haupt, Karsten A1 - Scheller, Frieder W. T1 - Enzymes as tools in MIP-sensors T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Molecularly imprinted polymers (MIPs) have the potential to complement antibodies in bioanalysis, are more stable under harsh conditions, and are potentially cheaper to produce. However, the affinity and especially the selectivity of MIPs are in general lower than those of their biological pendants. Enzymes are useful tools for the preparation of MIPs for both low and high-molecular weight targets: As a green alternative to the well-established methods of chemical polymerization, enzyme-initiated polymerization has been introduced and the removal of protein templates by proteases has been successfully applied. Furthermore, MIPs have been coupled with enzymes in order to enhance the analytical performance of biomimetic sensors: Enzymes have been used in MIP-sensors as tracers for the generation and amplification of the measuring signal. In addition, enzymatic pretreatment of an analyte can extend the analyte spectrum and eliminate interferences. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1098 KW - enzymatic MIP synthesis KW - template digestion KW - enzyme tracer KW - enzymatic analyte conversion KW - molecularly imprinted polymers Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-474642 SN - 1866-8372 IS - 1098 ER - TY - GEN A1 - Yarman, Aysu A1 - Scheller, Frieder W. T1 - The first electrochemical MIP sensor for tamoxifen T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - We present an electrochemical MIP sensor for tamoxifen (TAM)-a nonsteroidal anti-estrogen-which is based on the electropolymerisation of an O-phenylenediamine. resorcinol mixture directly on the electrode surface in the presence of the template molecule. Up to now only. bulk. MIPs for TAM have been described in literature, which are applied for separation in chromatography columns. Electro-polymerisation of the monomers in the presence of TAM generated a film which completely suppressed the reduction of ferricyanide. Removal of the template gave a markedly increased ferricyanide signal, which was again suppressed after rebinding as expected for filling of the cavities by target binding. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the TAM concentration between 1 and 100 nM. The TAM-imprinted electrode showed a 2.3 times higher recognition of the template molecule itself as compared to its metabolite 4-hydroxytamoxifen and no cross-reactivity with the anticancer drug doxorubucin was found. Measurements at + 1.1 V caused a fouling of the electrode surface, whilst pretreatment of TAM with peroxide in presence of HRP generated an oxidation product which was reducible at 0 mV, thus circumventing the polymer formation and electrochemical interferences. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1046 KW - molecularly imprinted polymers KW - anticancer drug KW - tamoxifen KW - electropolymerisation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476173 SN - 1866-8372 IS - 1046 ER -