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 - GEN A1 - Yarman, Aysu A1 - Scheller, Frieder W. T1 - How reliable is the electrochemical readout of MIP-sensors? T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 960 KW - molecularly imprinted polymers KW - electropolymerization KW - direct electron transfer KW - catalysis KW - redox marker KW - gate effect Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471608 SN - 1866-8372 IS - 960 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 - 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 - 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 - 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 - 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 - GEN A1 - Peng, Lei A1 - Yarman, Aysu A1 - Jetzschmann, Katharina J. A1 - Jeoung, Jae-Hun A1 - Schad, Daniel A1 - Dobbek, Holger A1 - Wollenberger, Ursula A1 - Scheller, Frieder W. T1 - Molecularly imprinted electropolymer for a hexameric heme protein with direct electron transfer and peroxide electrocatalysis N2 - For the first time a molecularly imprinted polymer (MIP) with direct electron transfer (DET) and bioelectrocatalytic activity of the target protein is presented. Thin films of MIPs for the recognition of a hexameric tyrosine-coordinated heme protein (HTHP) have been prepared by electropolymerization of scopoletin after oriented assembly of HTHP on a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold electrodes. Cavities which should resemble the shape and size of HTHP were formed by template removal. Rebinding of the target protein sums up the recognition by non-covalent interactions between the protein and the MIP with the electrostatic attraction of the protein by the SAM. HTHP bound to the MIP exhibits quasi-reversible DET which is reflected by a pair of well pronounced redox peaks in the cyclic voltammograms (CVs) with a formal potential of −184.4 ± 13.7 mV vs. Ag/AgCl (1 M KCl) at pH 8.0 and it was able to catalyze the cathodic reduction of peroxide. At saturation the MIP films show a 12-fold higher electroactive surface concentration of HTHP than the non-imprinted polymer (NIP). T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 362 KW - molecularly imprinted polymers KW - self-assembled monolayer KW - direct electron transfer KW - hydrogen peroxide KW - bioelectrocatalysis Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400627 ER - TY - GEN A1 - Menger, Marcus A1 - Yarman, Aysu A1 - Erdőssy, Júlia A1 - Yildiz, Huseyin Bekir A1 - Gyurcsányi, Róbert E. A1 - Scheller, Frieder W. T1 - MIPs and aptamers for recognition of proteins in biomimetic sensing N2 - Biomimetic binders and catalysts have been generated in order to substitute the biological pendants in separation techniques and bioanalysis. The two major approaches use either "evolution in the test tube" of nucleotides for the preparation of aptamers or total chemical synthesis for molecularly imprinted polymers (MIPs). The reproducible production of aptamers is a clear advantage, whilst the preparation of MIPs typically leads to a population of polymers with different binding sites. The realization of binding sites in the total bulk of the MIPs results in a higher binding capacity, however, on the expense of the accessibility and exchange rate. Furthermore, the readout of the bound analyte is easier for aptamers since the integration of signal generating labels is well established. On the other hand, the overall negative charge of the nucleotides makes aptamers prone to non-specific adsorption of positively charged constituents of the sample and the "biological" degradation of non-modified aptamers and ionic strength-dependent changes of conformation may be challenging in some application. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 357 KW - biomimetic recognition elements KW - aptamers KW - molecularly imprinted polymers KW - chemical sensors KW - aptasensors KW - in vitro selection KW - SELEX Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400496 ER -