Yazar "Azak, Hacer" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Catalase-conjugated surfaces: H2O2 detection based on quenching of tryptophan fluorescence on conducting polymers
    (Pergamon-Elsevier Science Ltd, 2021) Gelen, Sultan Sacide; Munkhbat, Tuvshinjargal; Rexhepi, Zuale; Kirbay, Fatma Ozturk; Azak, Hacer; Demirkol, Dilek Odaci
    Conducting polymers are promising materials used to prepare electrochemical and optical detection platforms for bioanalytical systems. After conjugation of biomolecules onto electmpolymerized monomers for preparation of multifunctional surfaces, they can be used to easily monitor small molecules, macromolecules, and cells. in this study, multifunctional monomer with indole (necessary for fluorescence detection of H2O2) and carboxyl functional groups (necessary for covalent immobilization of biological material) was synthesized, electropolymerized, modified with biomolecules (catalase) and then applied for the selective detection of target analyte (H2O2). Tryptophan sequestered dithione [3,2-b:2',3'-d] pyrmle (DTP-Trp) was synthesized and electropolymerized on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates, which is a transparent support. Afterward, catalase (CAT) was immobilized on the Poly(DTP-Trp) using a zero-length crosslinker, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), via covalent bonds between carboxyl groups of CAT and amino groups of Poly(DTP-Trp). Surface characterization of Poly(DTP-Trp)/CAT was done by scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX). The presence of Poly(DTP-Trp)/CAT on ITO-PET surfaces were also confirmed by electrochemical methods to show the success of support modification. Determination of H2O2 was investigated using fluorescence spectrometry based on quenching mechanism of H2O2 on the fluorescence of tryptophan. After optimization of working conditions of Poly(DTPTrp)/CAT, H2O2 detection in synthetic samples was done without any interference of the matrices.
  • Küçük Resim Yok
    Öğe
    Folic-Acid-Modified Conducting Polymer: Electrochemical Detection of the Cell Attachment
    (Wiley-V C H Verlag Gmbh, 2016) Azak, Hacer; Barlas, Firat Baris; Yildiz, Huseyin Bekir; Gulec, Kadri; Demir, Bilal; Demirkol, Dilek Odaci; Timur, Suna
    Here, postfunctionalization and bioapplication of a pi-conjugated polymer named 4-[4H-dithieno(3,2-b:2',3'-d)pyrrol-4-yl]aniline (DTP-aryl-NH2) are reported, which is successfully synthesized via electropolymerization onto the glassy carbon electrode. Folic acid (FA) is used to modify the amino functional polymer via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide chemistry for the further steps. The selective adhesion of folate receptor positive cells on the surface is followed by the electrochemical methods. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize stepwise modification of the electroactive surface. After optimization studies such as scan rate during the polymer deposition, FA amount for the efficient surface targeting, incubation time with the cells etc., analytical characterization is carried out. The surface morphologies at each step are imaged by using fluorescence microscopy.
  • Küçük Resim Yok
    Öğe
    A novel immobilization matrix for the biosensing of phenol: self assembled monolayers of calixarenes
    (Walter De Gruyter Gmbh, 2017) Tasci, Filiz; Sayin, Serkan; Seleci, Didem Ag; Demir, Bilal; Azak, Hacer; Yildiz, Huseyin Bekir; Demirkol, Dilek Odaci; Timur, Suna
    Aim: The development of calixarene based phenol biosensor. Methods: This study describes the application of a calixarene derivative, 5,17-diamino-25,27-bis(3-thiol-1- oxypropane)-26,28-dihydroxycalix[4] arene (HS-Calix-NH2) which has both amino and thiol functionalities, in the practical surface modifications for biomolecule binding. The structure of HS-Calix-NH2 allows easy interaction with Au surface and one-step biomolecule immobilization. Self-assembled monolayers (SAMs) of p-amino-functionalized mercaptoalkylcalixarene (HS-Calix-NH2) were formed onto the Au electrode. Then, Laccase (Lac) enzyme was immobilized onto the modified surface by crosslinking with glutaraldehyde (GA). Resulted electrode (HS-Calix-NH2/Lac) was used for the electrochemical analysis of phenolic compounds at -50 mV. Results: The linearity was observed in the range of 0.1-100 mu M and 1.0-100 mu M for catechol and phenol, respectively. The potential use of the biosensor was investigated for phenol analysis in artificial samples which simulate the industrial waste water, which is highly acidic and composed of concentrated salt, without needing any sample pre-treatment step. Conclusion: The prepared Lac biosensor has a potential for rapid, selective and easy detection of phenolic contaminations in samples.
  • Küçük Resim Yok
    Öğe
    Synthesis of an amine-functionalized naphthalene-containing conducting polymer as a matrix for biomolecule immobilization
    (Royal Soc Chemistry, 2013) Azak, Hacer; Guler, Emine; Can, Ummugulsum; Demirkol, Dilek Odaci; Yildiz, Huseyin Bekir; Talaz, Oktay; Timur, Suna
    N-functionalized dithienopyrroles (DTP-NH2) were synthesized and electropolymerized onto a graphite electrode as a novel conducting polymer matrix for biomolecule immobilization. H-1-NMR and C-13-NMR were utilized to investigate the characteristics of the monomer. After that, glucose oxidase (GOx) was immobilized onto the amino-functionalised matrix by means of glutaraldehyde. The surface morphologies of both DTP-NH2 and DTP-NH2-GOx were visualised by using SEM and fluorescence microscopy. The chronoamperometric signals of the electrochemical DTP-NH2-GOx biosensors were measured by monitoring the O-2 consumption during an enzymatic reaction in the presence of glucose at -0.7 V. After the optimization of the pH and scan number of the polymer deposition in batch mode, the DTP-NH2-GOx biosensor was also tested in Flow Injection Analysis (FIA) mode. The DTP-NH2-GOx biosensors had a very good linearity between 0.05 and 1.0 mM, and between 0.1 and 2.5 mM for glucose in batch and FIA modes, respectively. Finally, it was applied for glucose analysis in real samples where commercial glucose kits were used as the reference method to verify the data obtained with the proposed biosensor.
  • Küçük Resim Yok
    Öğe
    Synthesis of an amine-functionalized naphthalene-containing conducting polymer as a matrix for biomolecule immobilization
    (Royal Soc Chemistry, 2013) Azak, Hacer; Guler, Emine; Can, Ummugulsum; Demirkol, Dilek Odaci; Yildiz, Huseyin Bekir; Talaz, Oktay; Timur, Suna
    N-functionalized dithienopyrroles (DTP-NH2) were synthesized and electropolymerized onto a graphite electrode as a novel conducting polymer matrix for biomolecule immobilization. H-1-NMR and C-13-NMR were utilized to investigate the characteristics of the monomer. After that, glucose oxidase (GOx) was immobilized onto the amino-functionalised matrix by means of glutaraldehyde. The surface morphologies of both DTP-NH2 and DTP-NH2-GOx were visualised by using SEM and fluorescence microscopy. The chronoamperometric signals of the electrochemical DTP-NH2-GOx biosensors were measured by monitoring the O-2 consumption during an enzymatic reaction in the presence of glucose at -0.7 V. After the optimization of the pH and scan number of the polymer deposition in batch mode, the DTP-NH2-GOx biosensor was also tested in Flow Injection Analysis (FIA) mode. The DTP-NH2-GOx biosensors had a very good linearity between 0.05 and 1.0 mM, and between 0.1 and 2.5 mM for glucose in batch and FIA modes, respectively. Finally, it was applied for glucose analysis in real samples where commercial glucose kits were used as the reference method to verify the data obtained with the proposed biosensor.