Yazar "Yazgan, Idris" seçeneğine göre listele

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    Bienzymatic fluorescence detection based on paraoxonase and laccase on anthracene-sequestered polyamic acid films: A novel approach for inhibition-based sensors
    (Elsevier, 2020) Esen, Elif; Yazgan, Idris; Demirkol, Dilek Odaci
    A fluorescence assay based on paraoxonase (PO) and laccase (Lac) immobilized on anthracene-sequestered polyamic acid films is now being reported for the first time for ciprofloxacin (CFx) detection. in enzymatic reaction, PO converts phenyl acetate (PA) to acetic acid and phenol. The formed phenol is further oxidized by laccase using oxygen as a co-substrate. For indirectly fluorescence measurements of PA hydrolysis, increased fluorescence intensity was measured after oxygen consumption by laccase. This is because oxygen is quencher of anthracene (Ant) incorporated in the sequestered poly(amic) acid (PAA) film. The detection mechanism was based on inhibition of PO activity by CFx. Using PAA provided the advantage of controlling the film thickness. Firstly, morphology of PAA-Ant polymeric film was characterized by scanning electron microcopy (SEM) and the success of PO-Lac immobilization on PAA-Ant was proven by SEM plus Energy-dispersive X-ray spectroscopy (SEM-EDX) and fluorescence measurements. Then Ant-PAA/PO/Lac is calibrated for PA and CFx without any interfering of some potential interferences. All results make it a promising tool for monitoring CFx at minute levels in samples.
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    Brilliant green sequestered poly(amic) acid film for dual-mode detection: Fluorescence and electrochemical enzymatic biosensor
    (Elsevier Science Sa, 2018) Maiga, Mohomodou; Yazgan, Idris; Kariuki, Victor M.; Demirkol, Dilek Odaci; Sadik, Omowunmi A.; Timur, Suna
    Herein, we report a facile technique to fabricate fluorescent polymeric structure, brilliant-green sequestered poly(amic) acid film (BG-PAA), as enzyme support-material for biosensor applications. The structure and fluorescence properties of the fabricated BG-PAA membrane were investigated using H-1 NMR, scanning electron microscopy (SEM) and fluorescence microscopy. Glucose oxidase (GOx) was used as a model enzyme that immobilized on BG-PAA membrane using glutaraldehyde. The created BGPAA/GOx membrane was utilized to fabricate dual-purpose as fluorescent and electrochemical biosensors for the determination of glucose in beverages. Utilization of the dissolved oxygen in GOx mediated glucose oxidation resulted in alteration of the measured fluorescence and current intensity. In the fluorescence assay, the decreased concentration of oxygen causes the increased fluorescence intensity due to the elimination of quenching effect of oxygen on BG fluorescence. In amperometric assay, decrease in oxygen concentration was followed at -0.7 V. After optimization of working conditions linearity, limit of detection and repeatability of system were determined. Finally, BG-PAA/GOx was tested to analyze glucose in beverages. (C) 2017 Elsevier B.V. All rights reserved.
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    A colorimetric immunoassay for the detection of human vascular endothelial growth factor 165 (VEGF165) based on anti-VEGF-iron oxide nanoparticle conjugation
    (Springer Wien, 2024) Ceylan, Huelya Kudug; Kirbay, Fatma Ozturk; Yazgan, Idris; Elibol, Murat
    Vascular endothelial growth factor (VEGF) is an indispensable element in many physiological processes, while alterations in its level in the circulating system are signs of pathology-associated diseases. Therefore, its precise and selective detection is critical for clinical applications to monitor the progression of the pathology. In this study, an optical immunoassay biosensor was developed as a model study for detecting recombinant VEGF(165). The VEGF(165) sample was purified from recombinant Kluyveromyces lactis GG799 yeast cells. Indirect ELISA was used during the detection, wherein iron oxide nanoparticles (FeNPs) were utilized to obtain optical signals. The FeNPs were synthesized in the presence of lactose p-amino benzoic acid (LpAB). VEGF(165) antibody was conjugated to the LpAB-FeNPs through EDC/NHS chemistry to convert the iron oxide nanoparticles into VEGF(165) specific probes. The specificity of the prepared system was tested in the presence of potential serum-based interferents (i.e., glucose, urea, insulin, C-reactive protein, and serum amyloid A), and validation studies were performed in a simulated serum sample. The proposed immunoassay showed a wide detection range (0.5 to 100 ng/mL) with a detection limit of 0.29 ng/mL. These results show that the developed assay could offer a sensitive, simple, specific, reliable, and high-throughput detection platform that can be used in the clinical diagnostics of VEGF.
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    Laccase assay based on electrochemistry and fluorescence detection via anthracene sequestered poly(amic acid) films
    (Elsevier Science Bv, 2018) Esen, Elif; Yazgan, Idris; Demirkol, Dilek Odaci; Timur, Suna
    Phenols are among the most problematic organic compounds, which manipulates metabolism of living organisms and pose threat to environment. Detection of total phenol at the lowest allowable concentration is critical, so development of sensitive and easy to use methods have been heavily investigated. Hereby, for the first time, anthracene (Ant) was sequestered into poly(amic acid) (PAA) to form fluorescent and conductive film support for laccase (Lac) immobilization to quantify total phenol content at high specificity and selectivity. Ant-PAA/Lac films were applied to fluorescent and electrochemical quantification of phenol, which provided high sensitivity (LOD 46 mu M) and reproducibility (RSD, 0.5%) for the tested 10 phenolic compounds including phenol, catechol, 3-acetominophenol, hydroquinone, L-DOPA, 2,6-dimethylphenyl, syringalzadine, 3,5-dimethoxy-4-hydroxycinnamic acid, 2,5-dimethoxyaniline and guaiacol. The sensor system showed strong rejection to common organic interferent while real sample application revealed the applicability of the sensor. Therefore, the results can call the sensor system, particularly fluorescence-based quantification in 96-well plate, is an alternative approach for high-throughput screening of total phenolic compounds in waste-water at cost-effective manner.
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    Modification of chitosan-bead support materials with l-lysine and l-asparagine for alpha-amylase immobilization
    (Springer, 2018) Yazgan, Idris; Turner, Elizabeth G.; Cronmiller, Lauren E.; Tepe, Muammer; Ozturk, Taylan K.; Elibol, Murat
    Maltose syrups have got wide-range utilizations in a variety of applications from bakery to drug-development. alpha-Amylases are among the most widely utilized industrial enzymes due to their high specificity in production of maltose syrup from starch. However, enzymes are not stable in ex vivo conditions towards alteration in pH, temperature, and such other parameters as high salt concentrations and impurities, where immobilization is required to advance the stability of the enzyme with which approach the requirement of isolation of the enzyme from media is eliminated as well. In this study, Termamyl(A (R)) alpha-amylase was immobilized on the none-modified chitosan beads (NMCB), l-lysine-modified chitosan beads (LMCB), and l-asparagine-modified chitosan beads (AMCB) to assess effects of the support material on optimum conditions and kinetic parameters of the alpha-amylase activity in production of maltose from starch. Immobilization on NMCB, LMCB, and AMCB puts a strong influence on optimum pH, optimum temperature, stability, and kinetic parameters of alpha-amylase. Modification of chitosan beads with l-lysine and l-asparagine dramatically altered the overall immobilization yield, and enzyme's response to pH and temperature variations and the kinetic parameters. AMCB provided the best immobilization yield (49%), while LMCB only improved the yield by 2% from 22 to 24%.
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    Use of pyranose oxidase enzyme in inhibitor biosensing
    (Taylor & Francis Inc, 2008) Yazgan, Idris; Aydin, Tuba; Odaci, Dilek; Timur, Suna
    An inhibition based biosensing system was developed for the determination of glutathione (GSH) and ethanol (EtOH) as pyranose oxidase (PyOx) inhibitors. The PyOx was immobilized in carbon paste electrode and the amperometric detection of hydrogen peroxide through the enzymatic reaction was monitored at+0.9V versus Ag/AgCl. In addition to the optimization studies, analytical characteristics and the effect of various compounds on the biosensor response were researched. Finally, the proposed system was applied to analyze GSH and EtOH in real matrices.