@article{BognarSupalaYarmanetal.2022, author = {Bogn{\´a}r, Zs{\´o}fia and Supala, Eszter and Yarman, Aysu and Zhang, Xiaorong and Bier, Frank Fabian and Scheller, Frieder W. and Gyurcsanyi, R{\´o}bert E.}, title = {Peptide epitope-imprinted polymer microarrays for selective protein recognition}, series = {Chemical science / RSC, Royal Society of Chemistry}, volume = {13}, journal = {Chemical science / RSC, Royal Society of Chemistry}, number = {5}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2041-6539}, doi = {10.1039/d1sc04502d}, pages = {1263 -- 1269}, year = {2022}, abstract = {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.}, language = {en} } @article{YarmanKurbanoğluZebgeretal.2021, author = {Yarman, Aysu and Kurbanoğlu, Sevin{\c{c}} and Zebger, Ingo and Scheller, Frieder W.}, title = {Simple and robust}, series = {Sensors and actuators : B, Chemical : an international journal devoted to research and development of chemical transducers}, volume = {330}, journal = {Sensors and actuators : B, Chemical : an international journal devoted to research and development of chemical transducers}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0925-4005}, doi = {10.1016/j.snb.2020.129369}, pages = {12}, year = {2021}, abstract = {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.}, language = {en} } @article{CasertaZhangYarmanetal.2021, author = {Caserta, Giorgio and Zhang, Xiaorong and Yarman, Aysu and Supala, Eszter and Wollenberger, Ulla and Gyurcs{\´a}nyi, R{\´o}bert E. and Zebger, Ingo and Scheller, Frieder W.}, title = {Insights in electrosynthesis, target binding, and stability of peptide-imprinted polymer nanofilms}, series = {Electrochimica acta : the journal of the International Society of Electrochemistry (ISE)}, volume = {381}, journal = {Electrochimica acta : the journal of the International Society of Electrochemistry (ISE)}, publisher = {Elsevier}, address = {New York, NY [u.a.]}, issn = {0013-4686}, doi = {10.1016/j.electacta.2021.138236}, pages = {8}, year = {2021}, abstract = {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.}, language = {en} } @article{ZhangCasertaYarmanetal.2021, author = {Zhang, Xiaorong and Caserta, Giorgio and Yarman, Aysu and Supala, Eszter and Tadjoung Waffo, Armel Franklin and Wollenberger, Ulla and Gyurcsanyi, Robert E. and Zebger, Ingo and Scheller, Frieder W.}, title = {"Out of Pocket" protein binding}, series = {Chemosensors}, volume = {9}, journal = {Chemosensors}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors9060128}, pages = {13}, year = {2021}, abstract = {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.}, language = {en} } @article{OzcelikayKurbanogluYarmanetal.2020, author = {Ozcelikay, Goksu and Kurbanoglu, Sevinc and Yarman, Aysu and Scheller, Frieder W. and Ozkan, Sibel A.}, title = {Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin}, series = {Sensors and actuators : B, Chemical}, volume = {320}, journal = {Sensors and actuators : B, Chemical}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2020.128285}, pages = {7}, year = {2020}, abstract = {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.}, language = {en} } @article{KurbanogluYarman2020, author = {Kurbanoglu, Sevinc and Yarman, Aysu}, title = {Simultaneous determination of hydrochlorothiazide and irbesartan from pharmaceutical dosage forms with RP-HPLC}, series = {Turkish journal of pharmaceutical sciences}, volume = {17}, journal = {Turkish journal of pharmaceutical sciences}, number = {5}, publisher = {Turkish Pharmacists Association}, address = {{\c{C}}ankaya-Ankara}, issn = {1304-530X}, doi = {10.4274/tjps.galenos.2019.76094}, pages = {523 -- 527}, year = {2020}, abstract = {Objectives: In this work, a simple and rapid liquid chromatographic method for the simultaneous determination of irbesartan (IRBE) and hydrochlorothiazide (HCT) was developed and validated by reverse phase high performance liquid chromatography (RP-HPLC).
Materials and Methods: Experimental conditions such as different buffer solutions, various pH values, temperature, composition of the mobile phase, and the effect of flow rate were optimized.
Results: The developed RP-HPLC method for these antihypertensive agents was wholly validated and IRBE was detected in the linear range of 0.1-25 mu g mL(-1) and HCT was detected in the linear range of 0.25-25 mu g mL(-1). Moreover, the suggested chromatographic technique was successfully applied for the determination of the drugs in human serum and pharmaceutical dosage forms with limit of detection values of 0.008 mu g mL(-1) for IRBE and 0.012 mu g mL(-1) for HCT.
Conclusion: The proposed rapid analysis method of these antihypertensive drugs can be easily used and applied by pharmaceutical companies for which the analysis time is important.}, language = {en} } @article{OzcelikayKurbanogluZhangetal.2019, author = {Ozcelikay, Goksu and Kurbanoglu, Sevinc and Zhang, Xiaorong and S{\"o}z, {\c{C}}ağla Kosak and Wollenberger, Ulla and Ozkan, Sibel A. and Yarman, Aysu and Scheller, Frieder W.}, title = {Electrochemical MIP Sensor for Butyrylcholinesterase}, series = {Polymers}, volume = {11}, journal = {Polymers}, number = {12}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym11121970}, pages = {11}, year = {2019}, abstract = {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.}, language = {en} } @article{Yarman2018, author = {Yarman, Aysu}, title = {Electrosynthesized Molecularly Imprinted Polymer for Laccase Using the Inactivated Enzyme as the Target}, series = {Bulletin of the Korean chemical society}, volume = {39}, journal = {Bulletin of the Korean chemical society}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1229-5949}, doi = {10.1002/bkcs.11413}, pages = {483 -- 488}, year = {2018}, abstract = {The first molecularly imprinted polymer (MIP) for the recognition of the copper-enzyme laccase was successfully prepared by electropolymerizing scopoletin in the presence of alkaline-inactivated enzyme. Laccase-MIP and the control polymer without laccase (nonimprinted polymer, NIP) were characterized by voltammetry using the redox marker ferricyanide. After electropolymerization, the signals for ferricyanide for both the MIP and the NIP were almost completely suppressed and increased after removal of the target from the polymer layer. Rebinding of both inactivated and active laccase decreased the ferricyanide peak currents to almost equal extent. The relative decrease of signal suppression approached saturation above 10 nM. Furthermore, the surface activity of rebound laccase toward the oxidation of catechol was investigated. The surface activity approached saturation above 10 nM, a value close to the value of the measurements with ferricyanide. Interaction of NIP with laccase brought about a six times smaller signal of catechol oxidation.}, language = {en} } @article{ZhangYarmanErdossyetal.2018, author = {Zhang, Xiaorong and Yarman, Aysu and Erdossy, Julia and Katz, Sagie and Zebger, Ingo and Jetzschmann, Katharina J. and Altintas, Zeynep and Wollenberger, Ulla and Gyurcsanyi, Robert E. and Scheller, Frieder W.}, title = {Electrosynthesized MIPs for transferrin}, series = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, volume = {105}, journal = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, publisher = {Elsevier}, address = {Oxford}, issn = {0956-5663}, doi = {10.1016/j.bios.2018.01.011}, pages = {29 -- 35}, year = {2018}, abstract = {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.}, language = {en} } @article{JetzschmannYarmanRustametal.2018, author = {Jetzschmann, Katharina J. and Yarman, Aysu and Rustam, L. and Kielb, P. and Urlacher, V. B. and Fischer, A. and Weidinger, I. M. and Wollenberger, Ulla and Scheller, Frieder W.}, title = {Molecular LEGO by domain-imprinting of cytochrome P450 BM3}, series = {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}, volume = {164}, journal = {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}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7765}, doi = {10.1016/j.colsurfb.2018.01.047}, pages = {240 -- 246}, year = {2018}, abstract = {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.}, language = {en} }