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 - 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 - Kurbanoglu, Sevinc
A1 - Yarman, Aysu
T1 - Simultaneous determination of hydrochlorothiazide and irbesartan from pharmaceutical dosage forms with RP-HPLC
T1 - Farmasötik Dozaj Formlarında TF-YPSK ile Hidroklorotiyazid ve
İrbesartanın Eş Zamanlı Tayini
JF - Turkish journal of pharmaceutical sciences
N2 - 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.
N2 - Amaç: Bu çalışmada, irbesartan (IRBE) ve hidroklorotiyazidin (HCT) eşzamanlı tayini için basit ve hızlı bir ters fazlı yüksek performanslı sıvı
kromatografisi (TF-YPSK) yöntemi geliştirilmiş ve validasyon çalışmaları yapılmıştır.
Gereç ve Yöntemler: Deneysel koşullar; farklı tampon çözeltileri, çeşitli pH değerleri, sıcaklık, mobil fazın bileşimi, akış hızının etkisi gibi
parametrelerin üzerinden optimize edildi.
Bulgular: Bu antihipertansif ajanlar için geliştirilen TF-YPSK yönteminin tüm validasyon parametrelerine ilişkin çalışmalar yapılmış, ve IRBE 0,1-25
μg mL-1 doğrusal aralığında ve HCT 0,25-25 μg mL-1 doğrusal aralığında tespit edilmiştir. Ayrıca önerilen TF-YPSK yöntemi ile IRBE için 0,008 μg
mL-1 ve HCT için 0,012 μg mL-1 tayin alt sınır değerleri bulunmuştur. Geliştirilen yöntem, insan serumunda ve farmasötik dozaj formlarında bulunan
IRBE ve HCT’nin belirlenmesi için başarıyla uygulanmıştır.
Sonuç: Bu antihipertansif ilaçların miktar tayininde önerilen YPSK analiz yönteminin, analiz süresinin önemli olduğu ilaç firmalarında rahatlıkla
kullanılabileceği ve uygulanabileceği düşünülmektedir.
KW - HPLC
KW - irbesartan
KW - hydrochlorothiazide
KW - pharmaceutical dosage forms
Y1 - 2020
U6 - https://doi.org/10.4274/tjps.galenos.2019.76094
SN - 1304-530X
VL - 17
IS - 5
SP - 523
EP - 527
PB - Turkish Pharmacists Association
CY - Çankaya-Ankara
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
T1 - Development of a molecularly imprinted polymer-based electrochemical sensor for tyrosinase
JF - Turkish journal of chemistry
N2 - For the first time a molecularly imprinted polymer (MIP)-based sensor for tyrosinase is described. This sensor is based on the electropolymerization of scopoletin or o-phenylenediamine in the presence of tyrosinase from mushrooms, which has a high homology to the human enzyme. The template was removed either by treatment with proteinase Kor by alkaline treatment. The measuring signal was generated either by measuring the formation of a product by the target enzyme or by evaluation of the permeability of the redox marker ferricyanide. The o-phenylenediamine-based MIP sensor has a linear measuring range up to 50 nM of tyrosinase with a limit of detection of 3.97 nM (R 2 = 0.994) and shows good discrimination towards other proteins, e.g., bovine serum albumin and cytochrome c.
KW - Molecularly imprinted polymers
KW - biomimetic sensors
KW - tyrosinase
KW - electropolymerization
KW - scopoletin
KW - ophenylenediamine
Y1 - 2017
U6 - https://doi.org/10.3906/kim-1708-68
SN - 1300-0527
VL - 42
IS - 2
SP - 346
EP - 354
PB - Türkiye Bilimsel ve Teknik Araştırma Kurumu
CY - Ankara
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 -