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 - 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 - 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 JF - Polymers 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. KW - molecularly imprinted polymers KW - biomimetic sensors KW - butyrylcholinesterase KW - o-phenylenediamine KW - rivastigmine Y1 - 2019 U6 - https://doi.org/10.3390/polym11121970 SN - 2073-4360 VL - 11 IS - 12 PB - MDPI CY - Basel 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 - 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 - 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 - 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 - THES A1 - Zhang, Xiaorong T1 - Electrosynthesis and characterization of molecularly imprinted polymers for peptides and proteins Y1 - 2019 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 - 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 -