18 research outputs found

    Novel dendrimers containing redox mediator: Enzyme immobilization and applications

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    In this study, new dendrimers with a ferrocene core were produced by means of a divergent method for the immobilization of the glucose oxidase enzyme (GOx). Pt(II) and Pt(IV) ions were attached to the terminal groups of dendrimers. Metal-containing dendrimers, [Fc(MGlu)(2)-Aph-Pt(II)] and [Fc(MGlu)(2)-Aph-Pt(IV)], were obtained using the template method with aminophenol and Pt(II)/Pt(IV) cations. These compounds have been characterized by molar conductivity, magnetic susceptibility, FTIR, UV-Vis, H-1 NMR and LC-MS methods. The GOx enzyme was immobilized on the Fc(MGlu)(2), [Fc(MGlu)(2)-Aph-Pt(II)] and [Fc(MGlu)(2)-Aph-Pt(IV)] dendrimers, and the immobilized enzyme optimization parameters (substrate concentration, temperature, pH, reusability and storage capacity) were determined. Their K-m (mM) and V-max (mM.min(-1)) values were calculated from the Michaelis-Menten equation. The reusability of the immobilized glucose oxidase enzyme was investigated in an artificial urine medium. The research showed that [Fc(MGlu)(2)-Aph-Pt(II)] retains more than 61.23% of its initial activity after 10 successive cycles, which is a remarkable result. (C) 2019 Elsevier B.V. All rights reserved.Gazi University Research FundGazi University [05/2012-53, 05/2014-02]This work was supported by the Gazi University Research Fund (Project number: 05/2012-53 and 05/2014-02).WOS:0004681784000202-s2.0-8506550113

    PREPARATION OF FERROCENE CORE DENDRIMERS AND IMMOBILIZATION OF AChE FOR DETECTION OF DICLOFOP-METHYL HERBICIDE

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    The aim of this work was to investigate diclofop-methyl detection (found in a variety of herbicides) using novel dendrimers that have ferrocene cores, as well as their Pt(II) and Pt(IV) complexes. Novel dendrimer structures were synthesized and characterized by molar conductivity, magnetic susceptibility, FTIR, UV-Vis, H-1-NMR and LC-MS methods. Then, the AChE (acetylcholine esterase) enzyme was immobilized on the novel dendrimers, and the optimal parameters (pH, temperature, repeated use, storage stability, substrate concentration) were determined for immobilized AChE. Lastly, changes in absorbance intensity were measured, and calibration graphs were plotted that reflect the inhibition reaction of immobilized AChE with diclofop-methyl. The inhibition interaction of the enzyme immobilized to the Pt(II) ion containing dendrimers was higher than that of the Pt(IV) ion containing dendrimers.Gazi University Research FundGazi University [05/2016-10]This work was supported by the Gazi University Research Fund (Project number: 05/2016-10).WOS:0005080009000072-s2.0-8507939602

    Immobilization of GOx on Trp / Trp-Fc Functionalized Nanospheres: Improved of Reusability and Stability

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    In the study, new nanospheres support containing ferrocene were synthesized and characterized, then the properties of nanospheres as biocatalysis were researched. Novel support was prepared from (Aminomethyl) polystyrene (AMP), tryptophan (Trp) and ferrocene aldehyde (Fc) and the enzymatic properties of immobilized glucose oxidase enzyme (GOx) were investigated. Modified polystyrene was characterized IR spectra, Gel permeation chromatography and Scanning electron microscopy. Ferrocene-tagged nanospheres-GOx shows high reusability and storage capacity and fast incubation time determination of glucose. After 12 months, immobilized GOx to the AMP-Trp and AMP-Trp-Fc retained ca 20 % and 40 % for their original activity, respectively. High activities were found for modified polymers AMP-Trp-Fc retains more than 35 % of the initial activity after fifteenth successive cycles, which is a perfect performance.Gazi University Scientific Research FundGazi University [05/2011-59]The authors thank to the Gazi University Scientific Research Fund (Project number: 05/2011-59) for the financial support provided for this study and Esengul Ciftci for carryings out laboratory studies.WOS:00041881800001

    Spectroscopic characterization of novel d-amino acid-Schiff bases and their Cr(III) and Ni(II) complexes as antimicrobial agents

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    The aim of this work was to investigate the antibacterial and antifungal activities of novel d-amino acid-Schiff bases including fluorine atom and their Cr(III) and Ni(II) complexes. All these substances have been examined for antibacterial activity against pathogenic strains Listeria monocytogenes 4b ATCC19115, Staphylococcus aureus ATCC25923, Escherichia coli ATCC1280, Salmonella typhi H NCTC 901.8394, Brucella abortus (A.99, UK-1995) RSKK03026, Staphylococcus epidermis sp., Micrococus luteus ATCC9341, and Shigella dysenteria typ 10 NCTC 9351, and antifungal activity against Candida albicans Y-1200-NIH, Tokyo. The antimicrobial test results of these amino acid-Schiff base complexes exhibited better activity than some known antibiotics. In particular, diamagnetic Ni(II) complexes were more potent bactericides than all of the substances synthesized.Gazi University Research FundGazi University [05/2010-03, 05/2007-02]This work was supported by the Gazi University Research Fund (Project number: 05/2010-03 and 05/2007-02).WOS:0003137117000072-s2.0-8487399428

    Influence of load on the recycling stability of nanospheres attached platinium ion for determination of glucose

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    New nanospheres have been prepared with Pt2+ and Pt4+ for compare enzymatic properties of glucose oxidase enzyme (GOx). In this study nanoparticles, (aminomethyl)polystyrene (APS), 2-hydroxy-5-methylbenzaldehyde and Pt2+/Pt4+. have been synthesized by means of template and investigated the enzymatic properties of glucose oxidase enzyme (GOx) immobilized on there. The characteristics of the immobilized glucose oxidase (APS-Pt2+-GOx and APS-Pt4+-GOx) enzyme showed one optimum pH value. The influence of temperature, reusability and storage capacity on the free and immobilized glucose oxidase enzyme have been investigated. It is found that nanosphere including platinium atom exhibits excellent performance as the immobilized supporter of GOx, the immobilized enzyme demonstrates perfected storage and recycling stability. APS-Pt2+-GOx retains more than 30% of the initial activity after 32 successive cycles, which is a remarkable result. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.Gazi UniversityGazi University [05/2012-53, 05/2014-02]This work was supported by the Gazi University Research Fund (Project number: 05/2012-53 and 05/2014-02).WOS:0003562004000272-s2.0-8493006108

    Preparation of AChE immobilized microspheres containing thiophene and furan for the determination of pesticides by the HPLC-DAD method

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    In this study, acetylcholinesterase (AChE) enzyme immobilized polymeric microspheres were prepared to detect the dichlorvos (DDVP: 2,2-dichlorovinyl dimethyl phosphate) and the chlorpyrifos (O, O-Diethyl 0-3,5,6-trichloropyridin-2-yl phosphorothioate) pesticides. To produce polymeric supports, tris(2-aminoethyl)amine polystyrene (2AEPS) was reacted with thiophene carboxaldehyde and its derivatives; and 2AEPS was also reacted with furaldehyde and its derivatives. A total of six different ligands were synthesized (2AEPS-Tio, 2AEPS-5-CH(3)Tio, 2AEPS-5-NO2 Tio, 2AEPS-Fur, 2AEPS-5-CH(3)Fur, 2AEPS-5-NO(2)Fur). Polystyrene's spherical porous structure having large surface area and aldehyde groups were modified to enhance the efficiency of enzyme immobilization. In terms of the number of times it can be reused, the highest relative activity was found to be with 2AEPS-Tio-AChE at 71.28% after 10 cycles. HPLC-DAD system was used for detection of pesticides. For this purpose, the parameters which were thought to affect the response in HPLC-DAD analysis were optimized. Method validation was performed for pesticides. The decomposition reaction of the pesticide was followed by free and immobilized AChE enzyme using validated conditions. Using free AChE, the detection of limit (LOD) for DDVP and chlorpyrifos was found to be 2.57 mu g L-1 and 0.45 mu g L-1, respectively. When using immobilized AChE, the LOD values for DDVP and chlorpyrifos was obtained in the range of 0.42-0.75 mu g L-1 and 0.34-4.23 mu g L-1, respectively. (C) 2020 Elsevier B.V. All rights reserved.Kirklareli University Research Fund [KLUBAP-165]This work was supported by the Kirklareli University Research Fund (KLUBAP-165).WOS:0005874672000702-s2.0-8508839651

    Enzyme immobilization on polymeric microspheres containing Schiff base for detection of organophosphate and carbamate insecticides

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    In this study, polymeric microsphere including Schiff base TrisPS-pyr and TrisPS-pyr-Pt(II) were obtained by condensation reaction for improve the enzymatic properties of acetylcholinesterase (AChE) and detect harmful insects. Structures of the synthesized compounds were characterized by spectroscopic methods such as FT-IR, UV-Vis, SEM-EDX, GPC. Acetylcholinesterase enzyme was immobilized to these new polymeric microspheres and their properties such as activity, reusability and storage stability were investigated. In addition, the qualitative determination of carbamate [2,3-dihydro-2,2-dimethyl-7-benzofuranol N-methylcarbamate (carbofuran), 4-methylthio-3,5-xylyl methylcarbamate (methiocarb) and S-methyl-N- (methylcarbamoyl oxy) thioacetamide (methomyl)] and organophosphate [diethyl (dimethyl thiophosphoryl) succinate (malathion), O, S-dimethyl phosphoramidothioate acetyl (acephate) and chlorpyrifos methyl] insecticides by the immobilized enzyme was performed. The reason for the selection of these pesticides is because they are widely used to combat pests of agricultural products (hazelnut, corn, sugar beet, apple and tobacco) which are grown in our region. (C) 2019 Elsevier B.V. All rights reserved.Duzce University Research FundDuzce University [2017.07.06.661]This work was supported by Duzce University Research Fund (Project number: 2017.07.06.661).WOS:0004968109000082-s2.0-8507216720

    New Nanospheres to Use in the Determination of Imidan Phosmet and Vantex Pesticides

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    In this study, the usability of AChE immobilized nanospheres (NSs) was investigated to identify Imidan Phosmet and Vantex pesticides. Accordingly, (2AEPS-SalBr) coded nanosphere was synthesized in result of condensation of (Tris (2 aminoethyl)amine polymer and 5-bromine-2-hydroxy benzaldehyde. Then, new nanosphere coded 2AEPS-SalBr-Pd was synthesized using the template method. The structures of the synthesized nanospheres were characterized by the FT-IR, GPC, SEM/EDX and elemental analysis. Acetylcholinesterase (AChE) enzyme was immobilized to these nanospheres for the determination of Imidan and Vantex. The optimum conditions of the immobilized-AChE enzyme, the number of reuse, storage stability, and the kinetic parameters were determined. The immobilized AChE optimum pH was 8 for both supports, and the optimum temperature was 50 degrees C and 70 degrees C, respectively. Km and Vmax values were calculated as 1.443 mM and 0.251 mM/min for (2AEPS-SalBr)-AChE (pH 8, at 50 degrees C), and 0.680 mM and 0.157 mM/min for (2AEPS-SalBr-Pd)-AChE (pH 8, at 70 degrees C). Then the analyses of Imidan Phosmet and Vantex pesticides were carried out with immobilized AChE on nanospheres. As a result of the research, it was seen that Imidan Phosmet pesticide can be determined at a lower concentration than Vantex pesticide. [GRAPHICS] .Gazi University Research FundGazi University [05/2011-59]The authors thank Gazi University Research Fund (Project Number: 05/2011-59) for providing necessary facilities.WOS:0006074742000012-s2.0-8509943239
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