Browsing by Author "Teke, Mustafa"

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Citation - WoS: 68
Citation - Scopus: 75
Synthesis and Characterization of Electrospun Pva/Zn2+ Metal Composite Nanofibers for Lipase Immobilization With Effective Thermal, Ph Stabilities and Reusability
(ELSEVIER SCIENCE BV, 2019) Işık, Ceyhun; Arabacı, Gökmen; Doğaç, Yasemin İspirli; Deveci, İlyas; Teke, Mustafa
Polyvinyl alcohol (PVA)/Zn2+ electrospun nanofibers that were a kind of polymer/ionic metal composite was successfully embedded in the hybrid fibers for the first time in the literature, due to chemical interactions between PVA and Zn2+. Also, the nanofibers were used as carriers for the first time in enzyme immobilization. The nanofibers were optimized and synthesized by electrospinning technique according to the operational parameters like as PVA concentration (%), Zn2+ concentration (%), voltage (kV), needle tip-collector distance (cm) and injection speed (ml/h). The morphology and structure of the nanofibers were characterized by SEM, XRD, ATR-FTIR and TGA. Lipase was immobilized on the nanofibers by adsorption and crosslinking methods. According to immobilization results, nanofiber enhanced enzyme stability properties like as thermal stability, pH stability and reusability. Lipase immobilized nanofiber protected 90% of its activity after 14 reuses.
Citation - WoS: 19
Citation - Scopus: 22
Urease Immobilized Electrospun Pva/Chitosan Nanofibers With Improved Stability and Reusability Characteristics: an Application for Removal of Urea From Artificial Blood Serum
(TAYLOR & FRANCIS INC, 2020) Kutlu, Nur; Doğaç, Yasemin İspirli; Deveci, İlyas; Teke, Mustafa
Electrospun polyvinyl alcohol (PVA)/Chitosan nanofibers were successfully prepared and were used as carriers for the first time in urease immobilization. Also, urease immobilized electrospun PVA/Chitosan nanofibers were applied for the removal of urea from artificial blood serum by recycled reactor. The nanofibers were optimized and synthesized by electrospinning technique according to the operational parameters. The morphology and structure of the nanofibers were characterized by scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA). Urease was immobilized on the nanofibers by adsorption and crosslinking methods. According to immobilization results, nanofiber enhanced urease stability properties like thermal stability, pH stability, and reusability. Urease immobilized electrospun PVA/Chitosan nanofiber protected its activity by 85% after 10 uses and 45% after 20 uses. Urea removal rates of artificial blood serum were as follows: 100% at 1st cycle, 95% at 2nd, 3rd and 4th cycles; 85% at the 5th cycle; 76% at the 6th cycle, and 65% at the last three cycles.
Citation - WoS: 5
Citation - Scopus: 6
Zn2+-Doped Pva Composite Electrospun Nanofiber for Upgrading of Enzymatic Properties of Acetylcholinesterase**
(WILEY-V C H VERLAG GMBH, 2020) Işık, Ceyhun; Doğaç, Yasemin İspirli; Deveci, İlyas; Teke, Mustafa
Enzyme immobilization provides improve mechanical characteristic of enzymes and stability to environmental alters. It also helps to enzymes maintain their activities for a long time and offers the possibility to use them again. With these unique features, they can reduce production costs in industrial applications. In this study, acetylcholinesterase (AChE) immobilized on Zn2+-doped PVA nanofibers via adsorption and cross-linking methods. Morphological structures of Zn2+-doped PVA nanofibers were characterized by Scanning Electron Microscopy (SEM) before and after immobilization. It was observed that the enzyme gained resistance against temperature and pH changes occurring in the reaction medium after immobilization process. In addition, immobilized Zn2+-doped PVA nanofibers retained of its activity approximately 75 % after 8 reuse and its activity decreased below 50 % after 12 reuse. As a result, AChE immobilized Zn2+-doped PVA nanofibers offers numerous advantages for various biotechnological applications, such as hydrolysis and determination of pesticides, use in the structure of reactors and electrodes, thanks to the unique stability and reusability features that AChE gains after immobilization.