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Öğe A Strep-Tag Imprinted Polymer Platform for Heterogenous Bio(electro)catalysis(Wiley, 2024) Yarman, Aysu; Waffo, Armel F. T.; Katz, Sagie; Bernitzky, Cornelius; Kovacs, Norbert; Borrero, Paloma; Frielingsdorf, Stefan; Supala, Eszter; Dragelj, Jovan; Kurbanoğlu, SevinçMolecularly imprinted polymers (MIPs) are artificial receptors equipped with selective recognition sites for target molecules. One of the most promising strategies for protein MIPs relies on the exploitation of short surface-exposed protein fragments, termed epitopes, as templates to imprint binding sites in a polymer scaffold for a desired protein. However, the lack of highresolution structural data of flexible surface-exposed regions challenges the selection of suitable epitopes. Here, we addressed this drawback by developing a polyscopoletin-based MIP that recognizes recombinant proteins via imprinting of the widely used Strep-tag II affinity peptide (Strep-MIP). Electrochemistry, surfacesensitive IR spectroscopy, and molecular dynamics simulations were employed to ensure an utmost control of the Strep-MIP electrosynthesis. The functionality of this novel platform was verified with two Strep-tagged enzymes: an O2-tolerant [NiFe]-hydrogenase, and an alkaline phosphatase. The enzymes preserved their biocatalytic activities after multiple utilization confirming the efficiency of Strep-MIP as a general biocompatible platform to confine recombinant proteins for exploitation in biotechnology.Öğe A tale of captopril detection based on an electrochemical mip sensör(2024) Yarman, Aysu; Kurbanoğlu, SevinçAmaç: Bu çalışmada antihipertansif bir ilaç olan Kaptoprilin tespitine yönelik moleküler baskılama yöntemi ile hazırlanmış sensörler kullanılarak voltametrik bir yöntem geliştirilmesi amaçlanmıştır. Gereç ve Yöntem: Moleküler baskılama yöntemi ile camsı karbon elektroların yüzeylerinde moleküler baskınlanmış polimerler oluşturulmuş ve differansiyel puls voltammetri yöntemi ile Kaptoprilin analizi gerçekleştirilmiş, sensörün performansı incelenmiştir. Sonuç ve Tartışma: 2,62 pM teşhis sınırı değeri ile 50 pM Kaptopril seviyesine kadar doğrusal bir analiz gerçekleştirilmiştir. Seçicilik çalışmaları, Kaptoprilin, diğer girişim yapabilecek, parasetamol, askorbik asit ve L-prolin gibi maddelere göre daha yüksek elektrokimyasal cevaba sahip olduğunu göstermiştir.Öğe Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin(2020) Yarman, Aysu; Özçelikay, Göksu; Kurbanoğlu, Sevinç; Scheller, Frieder W.; Ozkan, Sibel A.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.Öğe Electrochemical MIP sensor for butyrylcholinesterase(Mdpi, 2019) Özçelikay, Göksu; Kurbanoğlu, Sevinç; Zhang, Xiaorong; Söz, Çağla; Wollenberger, Ulla; Özkan, Sibel Ayşıl; Scheller, Frieder W.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.Öğe Electrochemical MIP sensors for environmental analysis(Springer, 2023) Yarman, Aysu; Kurbanoğlu, Sevinç; Zhang, Xiaorong; Scheller, Frieder W.[Özet yok]Öğe Electrochemical MIP-sensors for drugs(Bentham Science Publ Ltd, 2018) Yarman, Aysu; Kurbanoğlu, Sevinç; Jetzschmann, Katharina J.; Özkan, Sibel A.; Wollenberger, Ulla; Scheller, Frieder W.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.Öğe Electrochemical readout of molecularly imprinted polymers: potentials and challenges(2020) Yarman, Aysu; Özçelikay, Göksu; Kurbanoğlu, Sevinç; Peng, Lei; Söz, Çağla; Özkan, Sibel Ayşıl; Wollenberger, Ulla; Scheller, Frieder W.Molecularly imprinted polymers (MIPs) are one of the most frequently studied alternative recognition elements in chromatography and sensorics. They are prepared by polymerizing the target analyte (socalled template) and functional monomers (in the presence or absence of cross-linkers). Subsequent removal of the template from the polymer network results in the formation of cavities with a molecular memory, which is complementary in size, shape and functionality to the template.Öğe Imprinted Polymers on the Route to Plastibodies for Biomacromolecules (MIPs), Viruses (VIPs), and Cells (CIPs)(Springer, 2024) Yarman, Aysu; Zhang, Xiaorong; Bagheri, Mandien; El-Sherbiny, Ibrahim M.; Hassan, Rabeay Y. A.; Kurbanoğlu, Sevinç; Waffo, Armel Franklin Tadjoung; Zebger, Ingo; Karabulut, Tutku Ceren; Bier, Frank F.; Lieberzeit, Peter; Scheller, Frieder W.Around 30% of the scientific papers published on imprinted polymers describe the recognition of proteins, nucleic acids, viruses, and cells. The straightforward synthesis from only one up to six functional monomers and the simple integration into a sensor are significant advantages as compared with enzymes or antibodies. Furthermore, they can be synthesized against toxic substances and structures of low immunogenicity and allow multi-analyte measurements via multi-template synthesis. The affinity is sufficiently high for protein biomarkers, DNA, viruses, and cells. However, the cross-reactivity of highly abundant proteins is still a challenge.Öğe Molecularly imprinted polymer based sensors for SARS-CoV-2: where are we now?(MDPI-Multidisciplinary Digital Publishing Institute, 2022) Yarman, Aysu; Kurbanoğlu, SevinçSince the first reported case of COVID-19 in 2019 in China and the official declaration from the World Health Organization in March 2021 as a pandemic, fast and accurate diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has played a major role worldwide. For this reason, various methods have been developed, comprising reverse transcriptase-polymerase chain reaction (RT-PCR), immunoassays, clustered regularly interspaced short palindromic repeats (CRISPR), reverse transcription loop-mediated isothermal amplification (RT-LAMP), and bio(mimetic)sensors. Among the developed methods, RT-PCR is so far the gold standard. Herein, we give an overview of the MIP-based sensors utilized since the beginning of the pandemic.Öğe Present state of MIP-based sensors for SARS-CoV-2(Elsevier, 2022) Yarman, Aysu; Kurbanoğlu, Sevinç; Scheller, Frieder W.[Özet yok]Öğe Quantum dot-based electrochemical molecularly imprinted polymer sensors: potentials and challenges(Elsevier, 2021) Yarman, Aysu; Kurbanoğlu, Sevinç; Erkmen, Cem; Uslu, Bengi; Scheller, Frieder W.[Özet yok]Öğe Simple and robust: The claims of protein sensing by molecularly imprinted polymers(2020) Yarman, Aysu; Kurbanoğlu, Sevinç; Zebger, Ingo; Scheller, Frieder W.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.Öğe Simultaneous determination of hydrochlorothiazide and irbesartan from pharmaceutical dosage forms with RP-HPLC(2000) Yarman, Aysu; Kurbanoğlu, SevinçObjectives: 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 ?g mL-1 and HCT was detected in the linear range of 0.25-25 ?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 µg mL-1 for IRBE and 0.012 µg 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.
