Allı, Abdulkadir | Hazer, Baki

Article | 2011 | JAOCS, Journal of the American Oil Chemists' Society88 ( 2 ) , pp.255 - 263

To diversify edible oil thermoresponsive polymer composites, polymeric linoleic acid peroxide (PLina) and polymeric linolenic acid peroxide (PLinl) were obtained by the autoxidation of linoleic acid (Lina) and linolenic acid (Linl), respectively. The autoxidation of Lina and Linl under air at room temperature rendered waxy soluble polymeric peroxide, having a soluble fraction in chloroform of more than 91 wt% and containing up to 1.0 wt% of peroxide. The soluble polymeric oil macro-peroxide was used to initiate the free radical polymerization of N-isopropylacrylamide, NIPAM, resulting in PLina-g-PNIPAM and PLinl-g-PNIPAM graft copol . . .ymers, respectively. The PNIPAM content of the graft copolymers was calculated using the elemental nitrogen analysis of graft copolymers. Thermal analysis, FTIR, 1H NMR, and SEM techniques were used in the characterization of the products. The hydrophobic effect of the fatty acid macro peroxides on the thermal response rate of the graft copolymers was investigated by means of swelling-deswelling behaviors in response to temperature change. They have a thermoresponsive character and exhibit a volume phase transition at approximately 27-30 °C, which is 1-4 °C lower than that of pure PNIPAM. A plastizer effect of PLina and PLinl in graft copolymers was observed, indicating a lower glass transition temperature than that of pure PNIPAM. © 2010 AOCS Daha fazlası Daha az

Öztürk, Temel | Göktaş, Melahat | Hazer, Baki

Article | 2011 | Journal of Macromolecular Science, Part A: Pure and Applied Chemistry48 ( 1 ) , pp.65 - 72

Synthesis of poly(methyl methacrylate-block-ethylene glycol-block-methyl methacrylate) triblock copolymers by reversible addition-fragmentation chain transfer (RAFT) by using a novel dual macro initiator (RAFT-agent) is reported. RAFT-agent is obtained from potassium salt of the ethyl xanthegonate and the terminally brominated poly(ethylene glycol) (Br-PEG-Br) which is synthesized by the reaction of poly(ethylene glycol) [PEG] with Mn= 3000 Dalton and 3-bromopropionyl chloride. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the polymerization reaction are evaluate . . .d. The characterization of the products is achieved using Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), gel-permeation chromatography (GPC), thermogravimetric analysis (TGA), and fractional precipitation () techniques. Molecular weights of the polymers obtained from GPC agreed with the theoretical values. RAFT polymerization is used to control the polymerization of MMA over a broad range of molecular weights. Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

Hazer, Derya Burcu | Hazer, Baki | Dinçer, Nazmiye

Article | 2011 | Journal of Biomedicine and Biotechnology2011 , pp.65 - 72

Hazer, Derya Burcu | Hazer, Baki

Article | 2011 | Journal of Polymer Research18 ( 2 ) , pp.251 - 262

We describe the synthesis and characterization of gold clusters embedded into poly (3-hydroxy octanoate-co-3-hydroxy-10-undecenoate) (PHOU), and evaluated the tissue response of the material upon implantation onto muscle tissue (rat). For this aim, PHOU was obtained by Pseudomonas oleovorans from octanoic acid (OA) and 10-undecenoic acid (UA) with a weight ratio of 50:50. The unsaturated co-polyester film in which HAuCl4 was dispersed was exposed to air at room temperature to produce gold clusters embedded into cross-linked PHOU. The cross-linking kinetics of the gold catalyzed PHOU autoxidation was followed by sol-gel analysis. In . . .vivo tissue reactions of the cross-linked PHOU embedded gold clusters were evaluated by subcutaneous implantation in rats. The rats appeared to be healthy throughout the implantation period. No symptom such as necrosis, abscess or tumor genesis was observed in the vicinity of the implants. Retrieved materials varied in their physical appearance after 6 weeks of implantation. AFM and SEM micrographs of the PHOU containing gold clusters were also taken. © 2010 Springer Science+Business Media B.V Daha fazlası Daha az

Kızılçay, Ebru | Çakmaklı, Birten | Hazer, Baki | Denkbaş, Emir Baki | Açikgöz, Bektaş

Article | 2011 | Journal of Applied Polymer Science119 ( 3 ) , pp.1610 - 1618

Poly(methyl methacrylate) (PMMA) and PMMA copolymers derived from plant oils (Polylinseed oil-g-PMMA, Polysoybean oil-g-PMMA, Polylinoleic acid-g-PMMA (PLina-g-PMMA) and Polyhydroxy alkanoate- sy-g-Polylinoleic acid-g-PMMA (PHA-g-PLina-g-PMMA)) as hydrophobic polymers, a series of hydrophobic microsphere or nanosphere dispersions, were prepared by the emulsion/solvent evaporation method. The diameters of the nanospheres and microspheres were measured by dynamic light scattering with a zetasizer, optically and by scanning electron microscopy. The magnetic quality of the microspheres was determined by the electron spin resonance techn . . .ique. Acetylsalicylic acid (aspirin, ASA) was used as a model drug and loaded into the microspheres during the preparation process. The effect of the stirring rate over the size and size distribution of the micro/nanospheres was evaluated, and the effects of copolymer types derived from plant oil/oily acids and the copolymer/drug ratios were evaluated. © 2010 Wiley Periodicals, Inc Daha fazlası Daha az

Bayramoğlu, Gülay | Hazer, Baki | Altıntaş, Begüm | Arıca, M. Yakup

Article | 2011 | Process Biochemistry46 ( 1 ) , pp.372 - 378

In this study, a functionalized hydrophobic polypropylene chloride membrane (PPC) was prepared by the amination of chlorinated polypropylene with hexamethylene diamine (APP). The PPC and APP membranes were characterized using SEM, FTIR and contact angle studies. The aminated polypropylene (APP) membrane was used for covalent immobilization of Candida rugosa lipase via glutaraldehyde coupling. The retained activity of the immobilized lipase was 76%. Kinetic analysis shows that the dependence of lipolytic activity of both free and immobilized lipase on tributyrin substrate concentration can be described by Michaelis-Menten model. The . . .estimated apparent Km values for the free and immobilized lipase were 2.9 and 8.4 mM, respectively. The Vmax values of free and immobilized enzymes were calculated as 926 and 741 U/mg enzyme, respectively. Optimal temperature was 5 °C higher for immobilized enzyme than that of the free enzyme. Thermal and storage stabilities were found to be increased upon immobilization. Finally, the immobilized lipase was used for the production of green apple flavor (i.e., ethyl valerate) in hexane medium. © 2010 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Kılıçay, Ebru | Demirbilek, Murat | Türk, Mustafa | Güven, Eylem | Hazer, Baki | Denkbaş, Emir Baki

Article | 2011 | EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES44 ( 3 ) , pp.310 - 320

Targeted drug delivery systems are one of the most promising alternatives for the cancer therapy. Rapid developments on nanomedicine facilitated the creation of novel nanotherapeutics by using different nanomaterials. Especially polymer based nanoparticles are convenient for this purpose. In this study; a natural polymer (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), PHBHHX) was used as a base matrix for the production of a novel nanotherapeutic including antineoplastic agent, Etoposide and attached folic acid as a ligand on the nanoparticles. Modified solvent evaporation technique was used for the production of PHBHHX nanoparticle . . .s and the average size of the obtained PHBHHX nanoparticles were observed in the range of 180 nm and 1.5 mu m by the change in experimental conditions (i.e., homogenization rate, surfactant concentration and polymer/solvent ratio). By the increase in homogenization rate and surfactant concentration, size of the nanoparticles was decreased, while the size was increased by the increase in polymer/solvent ratio. Drug loading ratio was also found to be highly affected by polymer/drug ratio. Surface charge of the prepared nanoparticles was also investigated by zeta potential measurements. In the cytotoxicity tests; Etoposide loaded and folic acid attached PHBHHX nanoparticles were observed as more effective on HeLa cells than Etoposide loaded PHBHHX nanoparticles without attached folic acid. The cytotoxicity of folic acid conjugated PHBHHX nanoparticles to cancer cells was found to be much higher than that of normal fibroblast cells, demonstrating that the folate conjugated nanoparticles has the ability to selectively target to cancer cells. In addition, apoptotic/necrotic activities were evaluated for all formulations of the PHBHHX nanoparticles and parallel results with cytotoxicity tests were obtained. These studies demonstrate that the folic acid attached and Etoposide loaded PHBHHX nanoparticles seem as promising for the targeted cancer therapy. (C) 2011 Elsevier B.V. All rights reserved Daha fazlası Daha az