Person: DEMİR, SERAP
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DEMİR
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SERAP
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Publication Metadata only Preparation and characterization of UV-curable polymeric support for covalent immobilization of xylanase enzyme(ELSEVIER, 2011) KAHRAMAN, MEMET VEZİR; Akdemir, Zumrut Seden; Demir, Serap; Kahraman, M. Vezir; Apohan, Nilhan KayamanThe hydroxyl group of poly(ethylene glycol) monoacrylate (PEGMA) was activated by 1 1'-carbonyldiimidazole (CDI) and then a xylanase enzyme was immobilized to amine active PEGMA UV-curable polymeric support formulation was prepared by mixing the xylanase bonded PEGMA aliphatic polyester 2-hydroxyethyl methacrylate (HEMA) poly(ethylene glycol) diacrylate (PEGDA) and photoinitiator After UV irradiation the enzymatic activity of the polymeric matrix was evaluated and compared with the corresponding free enzyme By immobilization the temperature resistance of the enzyme was improved and showed maximum activity at 60 C pH dependent activities of the free and immobilized enzymes were also investigated and it was found that the pH of maximum activity for the free enzyme was 60 while for the optimal pH of the immobilized enzyme was 65 The immobilized enzyme retained 75% of its activity after 33 runs The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition The results have confirmed the evidence of enzyme in the structure of the polymeric material (c) 2010 Elsevier B V All rights reservedPublication Metadata only Immobilization of alpha-amylase onto poly(glycidyl methacrylate) grafted electrospun fibers by ATRP(ELSEVIER, 2015) OKTAY, BURCU; Oktay, Burcu; Demir, Serap; Kayaman-Apohan, NilhanIn this study, novel alpha-amylase immobilized poly(vinyl alcohol) (PVA) nanofibers were prepared. The PVA nanofiber surfaces were functionalized with 2-bromoisobutyryl bromide (BiBBr) and followed by surface initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA). The morphology of the poly(glycidyl methacrylate) (PGMA) grafted PVA nanofibers was characterized by scanning electron microscopy (SEM). Also PGMA brushes were confirmed by X-ray photo electron microscopy (XPS). alpha-Amylase was immobilized in a one step process onto the PGMA grafted PVA nanofiber. The characteristic properties of the immobilized and free enzymes were examined. The thermal stability of the enzyme was improved and showed maximum activity at 37 degrees C by immobilization, pH values of the maximum activity of the free and immobilized enzymes were also found at 6.0 and 6.5, respectively. Free enzyme lost its activity completely within 15 days. The immobilized enzyme lost only 23.8% of its activity within 30 days. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Nonhydrolytic sol-gel synthesized oligosiloxane resin reinforced thiol-ene photocured coatings for the immobilization of acetylcholinesterase(SPRINGER, 2019) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Demir, SerapAcetylcholinesterase (AChE), which is responsible for the hydrolysis of neurotransmitter acetylcholine, is a critical enzyme for the nervous system and also a biomarker for organophosphorous pesticide detection. The immobilization of AChE is an active area of research and recently the use of sol-gel-derived materials for enzyme immobilization has gained a lot of attraction. In this work, AChE was covalently immobilized onto a photocured substrate which was reinforced with an oligosiloxane resin. The oligosiloxane resin was designed to have both vinyl and epoxide groups and prepared via nonhydrolytic sol-gel technique. The strategy employed in this study offered a platform that has good mechanical and thermal properties and also suitable for modification. Thus, AChE was also immobilized onto these substrates after amine modification of the epoxy groups and followed by glutaraldehyde activation. Over 80% enzyme immobilization yield was achieved. At certain pH values (5.5 and 8.5) and under relatively higher temperatures (above 40 degrees C) the immobilized enzymes were found to have higher catalytic activity than the free enzyme. Furthermore, by immobilization the reuse and the storage stability of the enzyme was improved and the stability of the immobilized enzyme against the inhibitory effects of certain metal cations was enhanced [GRAPHICS] . Nonhydrolytic sol-gel synthesized oligosiloxane resin reinforced thiol-ene photocured coatings for the immobilization of acetylcholinesterase. Emrah CAKMAKCI, Serap DEMIR. HighlightsAn oligosiloxane resin was prepared via nonhydrolytic sol-gel technique.The oligosiloxane resin was used to reinforce thiol-ene photocured coatings.Acetylcholinesterase was immobilized onto the photocured coatings.By immobilization, storage stability, reuse and metal ion resistance were improved.Publication Metadata only Immobilization of alpha- amylase on aminated polyimide membrane: Preparation, characterization, and properties(WILEY-V C H VERLAG GMBH, 2014) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Cigil, Asli Beyler; Danis, Ozkan; Demir, Serap; Kahraman, Memet Vezir-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3,4,4-Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4-oxydianline (4,4-ODA) based polyimide membranes were obtained via thermal imidization. Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were subjected to enzyme immobilization after GA activation. Immobilization efficiency and enzyme activity of -amylase was examined at various pH (3.0-8.0) and temperature (15-80 degrees C). The storage stability and reusability of immobilized -amylase were investigated. Immobilization yield was found as 359.53mg per gram of modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo stability than the free one. The storage stability and reusability improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 79.98% of its activity after 30 days. These results confirmed that -amylase was successfully immobilized and gained more stable character compared to the free enzyme.