Korkut, Şeyda | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2019 | Asia-Pacific Journal of Chemical Engineering14 ( 6 )

A copolymer poly(methyl methacrylate-co-vinylferrocene) was synthesized and used for the first time in a biofuel cell design. Bioanaode enzyme glucose oxidase and biocathode enzyme bilirubin oxidase were physically immobilized onto the copolymer-modified electrodes. Characterization studies were conducted by scanning electron microscopy, carbon-13, fourier transform infrared and hydrogen-1 nuclear magnetic resonance, and cyclic voltammograms. The designed biofuel cell was operated with linear sweep voltammetry. The maximum current was at 45°C with 120 µg of polymer amount. An improved power density of 323 µW cm-2 that is higher than . . . other ferrocene-based fuel cells was obtained with 10-mM glucose at 0.4 V with the designed bioanode. © 2019 John Wiley & Sons Ltd Daha fazlası Daha az

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2017 | Electroanalysis29 ( 10 ) , pp.2377 - 2384

Newly synthesized poly(styrene-g-oleic amide) was coated onto a rhodium nanoparticle modified glassy carbon (GC) surface for the fabrication of horseradish peroxidase based biosensor used for hydrogen peroxide detection. The rhodium modifed electrode presented ten times higher signal than unmodified electrode even at low elecrtroactive enzyme quantity by enhancing the electron transfer rate at the applied potential of -0.65 V. The biosensor designed by under the optimized rhodium electrodeposition time exhibited a fast response less than 5 s, an excellent operational stability with a relative standard deviation of 0.6 % (n=6), an ac . . .curacy of 96 % and a large linear range between 50 µM and 120 mM for hydrogen peroxide. Detection limit and the sensitivity parameters were calculated to be 44 µM and 57 µA mM-1 cm-2, respectively by preserving its entire initial response up to the 15 days, while only 20 % of its initial response was lost at the end of one month. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei Daha fazlası Daha az

Korkut, Şeyda | Kılıç, Muhammet Samet | Uzunçar, Sinan | Hazer, Baki

Article | 2016 | Analytical Letters49 ( 14 ) , pp.2322 - 2336

A carboxylated poly(styrene-b-isoprene-b-styrene) triblock copolymer was synthesized for the construction of an enzymatic fuel cell. Glucose oxidase and bilirubin oxidase were chemically immobilized via the carboxylated functional groups of the polymer. The enzymatic fuel cell working electrodes were modified with graphene to accelerate the electron transfer rate of the system. Essential design and operational parameters were carefully optimized for improving the power of the enzymatic fuel cell. A power density of 20 µW cm-2 with only 4 µg of immobilized bilirubin oxidase was generated from 30 mM glucose at 0.72 V. The improved enz . . .ymatic fuel cell was tested in a plant leaf. A power density of 14 nW cm-2 was generated with glucose produced by photosynthesis reactions conducted during 30 min in the leaf. © 2016, Taylor & Francis Group, LLC Daha fazlası Daha az

Hazer, Baki | Akyol, Elvan | Şanal, Timur | Guillaume, Sophie | Çakmaklı, Birten | Steinbuchel, Alexander

Article | 2019 | Polymer Bulletin76 ( 2 ) , pp.919 - 932

Poly(3-hydroxyalkanoate)s (PHAs) are a class of polymers receiving attention because of their potential as renewable, biodegradable and high-technology properties. Unlike most short chain length (scl) PHAs such as poly(3-hydroxybutyrate) (PHB), medium chain length (mcl) PHAs such as poly(3-hydroxyoctanoate) (PHO) exhibit low crystallinity and are elastomeric in character. PHB-b–PEG-b–PHO block copolymers can combine both properties in block copolymer matrix. In this study, we report the synthesis of the block copolymers combining the PHB and PHO blocks. Transamidation reactions of PHB with polyethylene glycol with primary amine yiel . . .d equimolar amounts and PHB with amine ends. PHO reacts with the modified PHB containing the amine end to give PHB-b–PEG-b–PHO block copolymers. Structural analysis of the products was performed by using 1H–, 13C, heteronuclear single quantum coherence NMR techniques. Thermal and mechanical properties of the block polymers were also evaluated. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature Daha fazlası Daha az

Korkut, Şeyda | Uzunçar, Sinan | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2016 | Instrumentation Science and Technology44 ( 6 ) , pp.614 - 628

A novel continuous flow biosensor based on gold nanoparticles and poly(propylene-co-imidazole) was developed for the online determination of p-benzoquinone. The amperometric response was measured as a function of p-benzoquinone concentration at an applied potential of -50 mV. The hydrogen peroxide concentration was optimized and fixed at 1 mM in samples. The mass transfer resistance of the copolymer film was minimized, and the flow cell was regenerated quickly at 1 mL/min. The resulting device provided good analytical performance based on a linear dynamic range from 5–100 µM, a short response time of 3 s, a detection limit of 3.3 µM . . ., excellent repeatability with a relative standard deviation of 0.82%, long-term stability of 95% after four weeks, and an accuracy of 105%. The gold nanoparticles enhanced the electron transfer rate on the electrode. The apparent Michaelis-Menten constant was 4 mM, showing that the enzyme retained catalytic specificity and provided high activity for p-benzoquinone. © 2016, Taylor & Francis Daha fazlası Daha az

Korkut, Şeyda | Uzunçar, Sinan | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2019 | Instrumentation Science and Technology47 ( 1 ) , pp.1 - 18

A new amperometric urea biosensor based on gold nanoparticle embedded poly(propylene-co-imidazole) was developed for the determination of urea. The urease adsorbed on the polymeric film catalyzed the hydrolysis of urea to ammonium and bicarbonate ions and the ammonium was then electrooxidized on the gold electrode with the aid of gold nanoparticles at +0.2 V versus Ag/AgCl using differential pulse voltammetry. The biosensor provided a linear current response to urea concentration from 0.1 to 30 mM, a detection limit of 36 µM, a relative standard deviation of 2.43% (n = 18), and excellent storage stability, as the current decrease wa . . .s only 3% after 75 days. The operation of the biosensor was evaluated by the analysis of municipal sewage wastewater collected from the inlet pipe of the treatment plant of Zonguldak City in Turkey. The effects of possible interferants were also characterized. © 2018, © 2018 Taylor & Francis Daha fazlası Daha az

Tığlı-Aydın, Rahime Seda | Hazer, Baki | Acar, Merve | Gümüşderelioğlu, Menemşe

Article | 2013 | Polymer Bulletin70 ( 7 ) , pp.2065 - 2082

A novel biocompatible copolymer membrane was synthesized and characterized for use in guided bone regeneration using polymeric soybean oil-g-polystyrene (PSO-g-PS) graft copolymer which was successfully obtained by free radical polymerization of styrene initiated by PSO peroxide as a macroinitiator at 80 C. Osteoblastic cellular activities of MC3T3-E1 cells on PSO-g-PS membranes with different soybean oil composition (PSO-g-PS1, PSO-g-PS2, and PSO-g-PS3) were evaluated. Nuclear magnetic resonance (1H NMR) spectra showed that PSO inclusion (mol%) was found to be 27, 69, and 51 % for PSO-g-PS1, PSO-g-PS2, and PSO-g-PS3 membranes, resp . . .ectively. Superior biocompatibility of the PSO-g-PS membranes was determined compared to polystyrene tissue culture plates (TCPS) as positive control. Cell proliferation was enhanced on PSO-g-PS2 and PSO-g-PS3 membranes compared to PSO-g-PS1 membranes (p < 0.001), and a statistically significant higher ALP value of MC3T3-E1 cells on PSO-g-PS2 membranes (p < 0.05) suggested that proliferation and differentiation of preosteoblastic on PSO-g-PS membranes were enhanced with regard to soybean oil content within the membranes. Thus, the present study suggests that PSO-g-PS2 membranes, which showed a favorable biological environment for the preosteoblastic cells, can be well suited for bone tissue engineering applications. © 2013 Springer-Verlag Berlin Heidelberg Daha fazlası Daha az

Allı, Sema | Tığlı-Aydın, Rahime Seda | Allı, Abdülkadir | Hazer, Baki

Article | 2015 | JAOCS, Journal of the American Oil Chemists' Society92 ( 3 ) , pp.449 - 458

Well-defined graft copolymers based on poly(?-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(?-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(?-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of ?-caprolactone initiated by PLina and one-pot synthesis of graft copolymers, and by ring-opening polymerization and free radical polymerization by using PLina, respectively. PLina-g-PCL, PLina-g-PSt-g-PCL3, and PLina-g-PSt-g-PCL4 copolymers containing 96.97, 75.04 and 80.34 mol% CL, respectively, have been investigated . . . regarding their enzymatic degradation properties in the presence of Pseudomonas lipase. In terms of weight loss, after 1 month, 51.5% of PLina-g-PCL, 18.8% of PLina-g-PSt-g-PCL3, and 38.4% of PLina-g-PSt-g-PCL4 were degraded, leaving remaining copolymers with molecular weights of 16,140, 83,220 and 70,600 Da, respectively. Introducing the PLina unit into the copolymers greatly decreased the degradation rate. The molar ratio of [CL]/[Lina] dramatically decreased, from 21.3 to 8.4, after 30 days of incubation. Moreover, reduced PCL content in PLina-g-PSt-g-PCL copolymers decreased the degradation rate, probably due to the PSt enrichment within the structure, which blocks lipase contact with PCL units. Thus, copolymerization of PCL with PLina and PSt units leads to a controllable degradation profile, which encourages the use of these polymers as promising biomaterials for tissue engineering applications. © AOCS 2015 Daha fazlası Daha az

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2015 | Materials Science and Engineering C47 , pp.165 - 171

This study describes the construction of an enzymatic fuel cell comprised of novel gold nanoparticles embedded poly(propylene-co-imidazole) coated anode and cathode. Working electrode fabrication steps and operational conditions for the fuel cell have been optimized to get enhanced power output. Electrical generation capacity of the optimized cell was tested by using the municipal wastewater sample. The enzymatic fuel cell system reached to maximum power density with 1 µg and 8 µg of polymer quantity and bilirubin oxidase on electrode surface, respectively. The maximum power output was calculated to be 5 µW cm- 2 at + 0.56 V (vs. Ag . . ./AgCl) in phosphate buffer (pH 7.4, 100 mM, 20 °C) by the addition of 15 mM of glucose as a fuel source. The optimized enzymatic fuel cell generated a power density of 0.46 µW cm- 2 for the municipal wastewater sample. Poly(propylene-co-imidazole) was easily used for a fuel cell system owing to its metallic nanoparticle content. The developed fuel cell will play a significant role for energy conversion by using glucose readily found in wastewater and in vivo mediums. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az

Korkut, Şeyda | Kılıç, Muhammet Samet | Sanal, Timur | Hazer, Baki

Article | 2017 | Materials Science and Engineering C76 , pp.787 - 793

This study describes construction of an enzymatic fuel cell comprised of poly(caprolactone-g-ethylene glycol) coated novel glucose oxidase anode and laccase cathode. Rationally designed poly(caprolactone-g-ethylene glycol) containing various poly(ethylene glycol) percentages ranging between 2.67 and 15.04% were synthesized chemically and tested separately for operation of the fuel cell system to achieve the best energy generation. The maximum power density was found to be 80.55 µW cm- 2 at 0.91 V (vs. Ag/AgCl) in pH 5, 100 mM citrate buffer (20 °C) by the addition of 30 mM of glucose from the electrodes coated with 11.34% poly(ethyl . . .ene glycol) containing polymer with a quantity of 600 µg. High poly(ethylene glycol) percentages with more numbers of long poly(ethylene glycol) brushes lead to the creation of a complexity in the polymer morphology and steric hindrance effect for electron transport. The graft copolymer was easily used for the fuel cell system owing to its biocompatible and microporous film morphology. The grafted polymer was able to facilitate enzymatic glucose oxidation and oxygen reduction while simultaneously producing high catalytic electrical currents. © 2017 Elsevier B.V Daha fazlası Daha az

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2014 | WIT Transactions on Ecology and the Environment181 , pp.213 - 224

Enzymatic biofuel cells (EFCs), which employ enzymes as a catalyst, convert the chemical energy released from the enzymatic oxidation of fuel into electrical energy. While chemical energy is being generated by the oxidation of fuel with enzymes, electricity is generated simultaneously by the movement of electrons released as a consequence of this chemical reaction from anode through cathode in enzymatic fuel cells. The major problem encountered in EFC studies is the difficult/slow electron transfer between the enzyme and the electrode. To mediate the electron transfer between the enzyme and the electrode's surface, low molecular wei . . .ght redox compounds called mediators are used in EFC. Higher power generation and minimal interference effects at a lower cell potential are achieved by using a mediator in EFC. The scope of this study is for the development of an enhanced electron transferred EFC with a proper mediator for the generation of electrical energy by the oxidation of glucose in domestic wastewater. Therefore, glucose in domestic wastewater is utilised for energy generation. In this study, Polypyrrole-2-carboxyclic acid was modified with various mediators such as, ferrocene, neutral red and p-benzoquinone, which were tested for this purpose. The maximum power density (100 nW/cm2) was observed for the ferrocene modified electrodes including glucose oxidase and laccase as anodic and cathodic enzyme, respectively. The electrode fabrication step was optimized with respect to the electrode material, its operational potential and the thickness of the polymeric film. The highest current values were obtained from the addition of 10 mM of glucose for the EFC system designed with the gold electrode material and operated with a working potential of 0.45 V. The most suitable polymeric film thickness was achieved in the cyclic voltammetry parameters set up with a scan rate of 50 mV/s and 25 cycles. The optimized EFC was tested in the domestic wastewater of Zonguldak City in Turkey. Ferrocene mediated EFC yielded a power density of 50-200 nW/cm2 for the domestic wastewater. © 2014 WIT Press Daha fazlası Daha az

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki | Erhan, Elif

Article | 2014 | Biosensors and Bioelectronics61 , pp.500 - 505

Newly synthesized gold and cobalt oxide nanoparticle embedded Polypropylene-g-Polyethylene glycol was used for a compartment-less enzymatic fuel cell. Glucose oxidase and bilirubin oxidase were selected as anodic and cathodic enzymes, respectively. Electrode fabrication and EFC operation parameters were optimized to achieve high power output. Maximum power density of 23.5µWcm-2 was generated at a cell voltage of +560mV vs Ag/AgCl, in 100mM PBS pH 7.4 with the addition of 20mM of synthetic glucose solution. 20µg of polymer amount with 185µg of glucose oxidase and 356µg of bilirubin oxidase was sufficient to get maximum performance. T . . .he working electrodes could harvest glucose, produced during photosynthesis reaction of Carpobrotus Acinaciformis plant, and readily found in real domestic wastewater of Zonguldak City in Turkey. © 2014 Elsevier B.V Daha fazlası Daha az