TY - JOUR
A1 - Jetzschmann, Katharina J.
A1 - Jagerszki, Gyula
A1 - Dechtrirat, Decha
A1 - Yarman, Aysu
A1 - Gajovic-Eichelmann, Nenad
A1 - Gilsing, Hans-Detlev
A1 - Schulz, Burkhard
A1 - Gyurcsanyi, Robert E.
A1 - Scheller, Frieder W.
T1 - Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition
JF - Advanced functional materials
N2 - Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from approximate to 0.04 x 10(-6) to 0.4 x 10(-6)m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP-AChE binding is 4.2 x 10(-7)m indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer is the effective suppression of the cross-reactivity toward competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by i) the shape-specific MIP filter, ii) the propidium-SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid.
KW - acetylcholinesterase
KW - biomimetic sensors
KW - molecularly imprinted electropolymers
KW - peripheral anionic site
KW - propidium
Y1 - 2015
U6 - https://doi.org/10.1002/adfm.201501900
SN - 1616-301X
SN - 1616-3028
VL - 25
IS - 32
SP - 5178
EP - 5183
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Yarman, Aysu
A1 - Schulz, Christopher
A1 - Sygmund, Cristoph
A1 - Ludwig, Roland
A1 - Gorton, Lo
A1 - Wollenberger, Ursula
A1 - Scheller, Frieder W.
T1 - Third generation ATP sensor with enzymatic analyte recycling
JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis
N2 - For the first time the direct electron transfer of an enzyme - cellobiose dehydrogenase, CDH - has been coupled with the hexokinase catalyzed competition for glucose in a sensor for ATP. To enhance the signal output for ATP, pyruvate kinase was coimmobilized to recycle ADP by the phosphoenolpyruvate driven reaction. The new sensor overcomes the limit of 1:1 stoichiometry of the sequential or competitive conversion of ATP by effective enzymatic recycling of the analyte. The anodic oxidation of the glucose converting CDH proceeds at electrode potentials below 0 mV vs. Ag vertical bar AgCl thus potentially interfering substances like ascorbic acid or catecholamines do not influence the measuring signal. The combination of direct electron transfer of CDH with the enzymatic recycling results in an interference-free and oxygen-independent measurement of ATP in the lower mu molar concentration range with a lower limit of detection of 63.3 nM (S/N=3).
KW - ATP
KW - Third generation sensor
KW - Enzymatic recycling
KW - Cellobiose dehydrogenase
KW - Hexokinase
KW - Pyruvate kinase
Y1 - 2014
U6 - https://doi.org/10.1002/elan.201400231
SN - 1040-0397
SN - 1521-4109
VL - 26
IS - 9
SP - 2043
EP - 2048
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Yarman, Aysu
A1 - Scheller, Frieder W.
T1 - The first electrochemical MIP sensor for tamoxifen
JF - Sensors
N2 - We present an electrochemical MIP sensor for tamoxifen (TAM)-a nonsteroidal anti-estrogen-which is based on the electropolymerisation of an O-phenylenediamine. resorcinol mixture directly on the electrode surface in the presence of the template molecule. Up to now only. bulk. MIPs for TAM have been described in literature, which are applied for separation in chromatography columns. Electro-polymerisation of the monomers in the presence of TAM generated a film which completely suppressed the reduction of ferricyanide. Removal of the template gave a markedly increased ferricyanide signal, which was again suppressed after rebinding as expected for filling of the cavities by target binding. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the TAM concentration between 1 and 100 nM. The TAM-imprinted electrode showed a 2.3 times higher recognition of the template molecule itself as compared to its metabolite 4-hydroxytamoxifen and no cross-reactivity with the anticancer drug doxorubucin was found. Measurements at + 1.1 V caused a fouling of the electrode surface, whilst pretreatment of TAM with peroxide in presence of HRP generated an oxidation product which was reducible at 0 mV, thus circumventing the polymer formation and electrochemical interferences.
KW - molecularly imprinted polymers
KW - anticancer drug
KW - tamoxifen
KW - electropolymerisation
Y1 - 2014
U6 - https://doi.org/10.3390/s140507647
SN - 1424-8220
VL - 14
IS - 5
SP - 7647
EP - 7654
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Yarman, Aysu
A1 - Scheller, Frieder W.
T1 - The first electrochemical MIP sensor for tamoxifen
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - We present an electrochemical MIP sensor for tamoxifen (TAM)-a nonsteroidal anti-estrogen-which is based on the electropolymerisation of an O-phenylenediamine. resorcinol mixture directly on the electrode surface in the presence of the template molecule. Up to now only. bulk. MIPs for TAM have been described in literature, which are applied for separation in chromatography columns. Electro-polymerisation of the monomers in the presence of TAM generated a film which completely suppressed the reduction of ferricyanide. Removal of the template gave a markedly increased ferricyanide signal, which was again suppressed after rebinding as expected for filling of the cavities by target binding. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the TAM concentration between 1 and 100 nM. The TAM-imprinted electrode showed a 2.3 times higher recognition of the template molecule itself as compared to its metabolite 4-hydroxytamoxifen and no cross-reactivity with the anticancer drug doxorubucin was found. Measurements at + 1.1 V caused a fouling of the electrode surface, whilst pretreatment of TAM with peroxide in presence of HRP generated an oxidation product which was reducible at 0 mV, thus circumventing the polymer formation and electrochemical interferences.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1046
KW - molecularly imprinted polymers
KW - anticancer drug
KW - tamoxifen
KW - electropolymerisation
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476173
SN - 1866-8372
IS - 1046
ER -
TY - JOUR
A1 - Yarman, Aysu
A1 - Gröbe, Glenn
A1 - Neumann, Bettina
A1 - Kinne, Mathias
A1 - Gajovic-Eichelmann, Nenad
A1 - Wollenberger, Ursula
A1 - Hofrichter, Martin
A1 - Ullrich, Rene
A1 - Scheibner, Katrin
A1 - Scheller, Frieder W.
T1 - The aromatic peroxygenase from Marasmius rutola-a new enzyme for biosensor applications
JF - Analytical & bioanalytical chemistry
N2 - The aromatic peroxygenase (APO; EC 1.11.2.1) from the agraric basidomycete Marasmius rotula (MroAPO) immobilized at the chitosan-capped gold-nanoparticle-modified glassy carbon electrode displayed a pair of redox peaks with a midpoint potential of -278.5 mV vs. AgCl/AgCl (1 M KCl) for the Fe(2+)/Fe(3+) redox couple of the heme-thiolate-containing protein. MroAPO oxidizes aromatic substrates such as aniline, p-aminophenol, hydroquinone, resorcinol, catechol, and paracetamol by means of hydrogen peroxide. The substrate spectrum overlaps with those of cytochrome P450s and plant peroxidases which are relevant in environmental analysis and drug monitoring. In M. rotula peroxygenase-based enzyme electrodes, the signal is generated by the reduction of electrode-active reaction products (e.g., p-benzoquinone and p-quinoneimine) with electro-enzymatic recycling of the analyte. In these enzyme electrodes, the signal reflects the conversion of all substrates thus representing an overall parameter in complex media. The performance of these sensors and their further development are discussed.
KW - Unspecific peroxygenase
KW - Cytochrome P450
KW - Biosensors
KW - Phenolic substances
Y1 - 2012
U6 - https://doi.org/10.1007/s00216-011-5497-y
SN - 1618-2642
VL - 402
IS - 1
SP - 405
EP - 412
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Peng, Lei
A1 - Utesch, Tillmann
A1 - Yarman, Aysu
A1 - Jeoung, Jae-Hun
A1 - Steinborn, Silke
A1 - Dobbek, Holger
A1 - Mroginski, Maria Andrea
A1 - Tanne, Johannes
A1 - Wollenberger, Ursula
A1 - Scheller, Frieder W.
T1 - Surface-Tuned Electron Transfer and Electrocatalysis of Hexameric Tyrosine-Coordinated Heme Protein
JF - Chemistry - a European journal
N2 - Molecular modeling, electrochemical methods, and quartz crystal microbalance were used to characterize immobilized hexameric tyrosine-coordinated heme protein (HTHP) on bare carbon or on gold electrodes modified with positively and negatively charged self-assembled monolayers (SAMs), respectively. HTHP binds to the positively charged surface but no direct electron transfer (DET) is found due to the long distance of the active sites from the electrode surfaces. At carboxyl-terminated surfaces, the neutrally charged bottom of HTHP can bind to the SAM. For this "disc" orientation all six hemes are close to the electrode and their direct electron transfer should be efficient. HTHP on all negatively charged SAMs showed a quasi-reversible redox behavior with rate constant k(s) values between 0.93 and 2.86 s(-1) and apparent formal potentials E-app(0)' between -131.1 and -249.1 mV. On the MUA/MU-modified electrode, the maximum surface concentration corresponds to a complete monolayer of the hexameric HTHP in the disc orientation. HTHP electrostatically immobilized on negatively charged SAMs shows electrocatalysis of peroxide reduction and enzymatic oxidation of NADH.
KW - electrochemistry
KW - electron transfer
KW - heme proteins
KW - molecular modeling
KW - monolayers
Y1 - 2015
U6 - https://doi.org/10.1002/chem.201405932
SN - 0947-6539
SN - 1521-3765
VL - 21
IS - 20
SP - 7596
EP - 7602
PB - Wiley-VCH
CY - Weinheim
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 - 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 - Yarman, Aysu
A1 - Wollenberger, Ursula
A1 - Scheller, Frieder W.
T1 - Sensors based on cytochrome P450 and CYP mimicking systems
JF - ELECTROCHIMICA ACTA
N2 - Cytochrome P450 enzymes (CYPs) act on more than 90 percent of all drugs currently on the market. The catalytic cycle requires electron supply to the heme iron in the presence of oxygen. Electrochemistry allows to characterise the reaction mechanism of these redox enzymes by observing the electron transfer in real time. According to the number of publications on protein electrochemistry CYP has the third position after glucose oxidase and cytochrome c. CYP based enzyme electrodes for the quantification of drugs, metabolites or pesticides have been developed using different iso-enzymes. A crucial step in the sensor development is the efficiency of coupling the biocatalytic systems with the electrode is. In the 1970s the direct electron transfer of heme and heme peptides called microperoxidases (MPs) was used as model of oxidoreductases. They exhibit a broad substrate spectrum including hydroxylation of selected aromatic substrates, demethylation and epoxidation by means of hydrogen peroxide. It overlaps with that of P450 making heme and MPs to alternate recognition elements in biosensors for the detection of typical CYP substrates. In these enzyme electrodes the signal is generated by the conversion of all substrates thus representing in complex media an overall parameter. By combining the biocatalytic substrate conversion with selective binding to a molecularly imprinted polymer layer the specificity has been improved. Here we discuss different approaches of biosensors based on CYP, microperoxidases and catalytically active MIPs and discuss their potential as recognition elements in biosensors. The performance of these sensors and their further development are discussed. (C) 2013 Elsevier Ltd. All rights reserved.
KW - Cytochrome P450
KW - Microperoxidases
KW - Catalytically active molecularly imprinted polymers
KW - Biosensors
KW - Personalised medicine
Y1 - 2013
U6 - https://doi.org/10.1016/j.electacta.2013.03.154
SN - 0013-4686
SN - 1873-3859
VL - 110
SP - 63
EP - 72
PB - PERGAMON-ELSEVIER SCIENCE LTD
CY - OXFORD
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 -