Browsing by Author "Mirioglu, Muge"

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Horseradish peroxidase (HRP) nanoflowers-mediated polymerization of vinyl monomers
(SPRINGER NATURE LINK, 2024) Ozaydin, Gulbahar; Mirioglu, Muge; Kaplan, Naime; Dadi, Seyma; Ocsoy, Ismail; Gokturk, Ersen; 0000-0001-6280-3966; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Dadi, Seyma
The effects of flower-shaped hybrid nano biocatalyst (hFe-NFs) from coordination between horseradish peroxidase (HRP) enzyme and Fe2+ ions on the free-radical polymerization reactions of three different vinyl monomers (styrene, methylmethacrylate and acrylamide) were investigated. Polymerizations of styrene and methylmethacrylate (MMA) were performed under emulsion conditions using three different surfactants in the presence of acetylacetone (AcAc) and hydrogen peroxide (H2O2) initiator. Polymerization of water soluble acrylamide was accomplished under surfactant-free media. According to the obtained outcomes, hFe-NFs exhibited higher catalytic activity towards polymerization of vinyl monomers compared to the free-HRP enzyme in terms of yields and the number average molecular weights (Mn) of the synthesized polymers. hFe-NFs also demonstrated very high thermal stability. While optimum polymerization of styrene was achieved at room temperature (RT), the highest polymerization yields for acrylamide and MMA were respectively accomplished at 70 and 60 degrees C in which free-HRP enzyme loses its catalytic activity. Preparation of the flower-shaped hFe-NFs, therefore, enables inexpensive and stable catalyst system for free-radical polymerization of vinyl monomers compared to free-HRP enzyme. Increasing catalytic activity and stability of hFe-NFs at higher reaction temperatures are very crucial for utilization of these types of catalysts in both scientific and industrial purposes.
Investigation of Peroxidase-Like Activity of Flower-Shaped Nanobiocatalyst from Viburnum Opulus L. Extract on the Polymerization Reactions
(Turkish Chemical Society, 2024) Kalayci, Berkant; Kaplan, Naime; Mirioglu, Muge; Dadi, Seyma; Ocsoy, Ismail; Gokturk, Ersen; 0000-0001-6280-3966; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Dadi, Seyma
Here, we report the effects of peroxidase-mimicking activity of flower shaped hybrid nanobiocatalyst obtained from Viburnum-Opulus L. (Gilaburu) extract and Cu2+ ions on the polymerization of phenol and its derivatives (guaiacol and salicylic acid). The obtained nanoflowers exhibited quite high catalytic activity upon the polymerization of phenol and guaiacol. The yields and the number average molecular weights of the obtained polymers were significantly high. Due to solubility issue of salicylic acid in aqueous media, polymerization of salicylic acid resulted in very low yields. Free-horseradish peroxidase (HRP) enzyme is known to be losing its catalytic activity at 60 °C and above temperatures. However, the synthesized nanoflowers exhibited quite high catalytic activity even at 60 °C and above reaction temperatures. This provides notable benefits for reactions needed at high temperatures, and it is very important to use these kinds of nanobiocatalysts for both scientific studies and industrial applications.