Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 1Citation - Scopus: 1Investigation of the Free-Radical Polymerization of Vinyl Monomers Using Horseradish Peroxidase (HRP) Nanoflowers(Springer, 2025-01-24) Ozaydin, Gulbahar; Mirioglu, Muge; Dadi, Seyma; Ocsoy, Ismail; Gokturk, ErsenIn this study, we report the production of flower-shaped HRP-Cu2+ hybrid nano biocatalyst (HRP-Cu2+ HNF) from the complexation between horseradish peroxidase (HRP) enzyme and Cu2+ ions, and investigate catalytic activity and stability of the obtained nanoflowers on the polymerization of some vinyl monomers (styrene, methylmethacrylate, acrylamide and N-isopropylacrylamide). Polymerizations of these monomers, except water soluble acrylamide, were accomplished under emulsion conditions using cationic, anionic and non-ionic surfactants in the presence of hydrogen peroxide (H2O2) and 2,4-pentanedione mediator. Optimum polymerizations were achieved under the conditions of non-ionic surfactant (tween 40) used. HRP-Cu2+ HNF mediated polymerizations resulted in very high yields and molecular weights (Mn) of the polymers. Optimum polymerization of styrene with 84% of yield (Mn = 319 kDa) was accomplished at room temperature. However, the highest polymerization yields for acrylamide (96%, Mn = 171 kDa) and N-isopropylacrylamide (85%, Mn = 185 kDa) was achieved at 70 degrees C. Similarly, optimum polymerization of methylmethacrylate was accomplished with 84% of yield (Mn = 190 kDa) at 60 degrees C. While free-HRP loses its catalytic activity at 60 degrees C and above temperatures, HRP-Cu2+ HNF showed very high catalytic activity and stability even at 70 degrees C. Increasing activity and stability of hybrid nanoflowers provide significant advantages for both scientific and industrial applications.Book Part Citation - Scopus: 1Green Magnetic Nanoparticles in Enzyme Immobilization(Elsevier, 2024) Dadi, Seyma; Alrifai, Wardishan Kassem; Öçsoy, IsmailEnzymes as highly efficient biocatalysts are widely used in various biotechnological sectors including cosmetic, textile, food, and detergent. However, their practical applications can be hampered due to high expense and challenges in the extraction, separation, and purification steps. Additionally, enzymes have limited activity and stability at high temperature and different pH values. Aiming to overcome these challenges, various nanoparticles (NPs) have been used as supporting matrices and carriers for enzyme immobilization. Among the NPs, in recent years, green magnetic nanoparticles (GMNPs) have attracted great attention as ideal support material for enzyme immobilization owing to their exceptional properties, such as their easy preparation, low toxicity, biocompatibility, and lower diffusion limitation. These properties enable the immobilized enzymes on GMNPs to be used in many different applications. This chapter aims to summarize the recent developments about enzyme immobilization on magnetic nanoparticles and GMNPs and their practical applications. © 2024 Elsevier B.V., All rights reserved.Book Part Citation - Scopus: 1Green Magnetic Nanoparticles: Recent Advancements in Synthesis and Characterization(Elsevier, 2024) Alrifai, Wardishan Kassem; Dadi, Seyma; Öçsoy, IsmailVarious types of nanoparticles (NPs) have been used in numerous scientific and industrial fields. Specifically, magnetic nanoparticles (MNPs) have drawn great attention in the last two decades concerning their synthesis, development, functionality, and relevant applications in a variety of areas including data storage, wastewater treatment, catalysis, bio-separation, and medicine. Several strategies have been developed to synthesize MNPs with various shapes, sizes, and compositions. The magnetization performance of MNPs is directly dependent on their high size, size distribution, composition, and crystallinity of the NP. The highly crystalline, monodisperse, and uniform MNPs called “high-quality MNPs” with unique magnetic properties have been synthesized by chemical synthesis method in the presence of hydrophobic surfactant (long hydrocarbon chain) and nonpolar solvents at high temperatures; however, these MNPs are toxic, insoluble in water and lack of use in all bio-related applications. To use these MNPs in biological applications, it is mandatory to apply a ligand exchange process to remove hydrophilic ligands and make MNPs soluble and stable in aqueous solutions. To address these issues, green synthesis methods using biomolecules, plant extracts, and microorganisms have been developed for the synthesis of biocompatible MNPs. This chapter aims to display recent developments in the synthesis of MNPs with green synthesis methods and in their characterization. © 2024 Elsevier B.V., All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Benefiting From Both Ethanol Oxidation and Bidentate Thiol Groups of DHLA Ligands Under Photoirradiation for Synthesis of Au Nanoparticles With Their Catalytic and Peroxidase Like Activity(Amer Chemical Soc, 2025-04-08) Temur, Nimet; Dadi, Seyma; Dogan, Ayse Nur; Nisari, Mustafa; Avan, Ilker; Ocsoy, IsmailIn this work, we rationally synthesized quite stable gold nanoparticles (AuNPs) using dihydrolipoic acid (DHLA) and DHLA-aspartame (DHLA-Asptm) as both reducing and stabilizing agents in a mixture of water/ethanol at RT under photoirradiation in 10 min. The novelty of this work is that benefiting from both the oxidation of ethanol to ethanal and having the bidentate thiol groups of DHLA, stable DHLA@AuNPs and DHLA-Asptm@AuNPs were successfully and rapidly formed without additional reducing reagents. We systematically examined the formation of DHLA@AuNPs and DHLA-Asptm@AuNPs under different pH values and reaction temperatures. Furthermore, the salt tolerance of DHLA@AuNPs and DHLA-Asptm@AuNPs was tested in a series of sodium chloride solutions. We showed the catalytic and peroxidase-like activities of DHLA@AuNPs against 4-nitrophenol and 3,3 ',5,5 '-tetramethylbenzidine. The AuNPs were characterized by UV-vis spectrophotometry, scanning transmission electron microscopy, zeta potential, and dynamic light scattering.