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    Catechin Encapsulated Antioxidant Electrospun Nanofibers: A Comparative Study between Cyclodextrin Complex Nanofibers and Poly(vinyl alcohol) Nanofibers
    (Amer Chemical Soc, 2023) Yildiz, Zehra Irem; Topuz, Fuat; Uyar, Tamer
    Catechin is a plant polyphenol with a strong antioxidant effect. However, its use is limited due to its poor water solubility and sensitivity to light and oxygen. Here, catechin could be solubilized by inclusion complexation with cyclodextrin (CD) (CD-IC), and their solutions were electrospun into fibers in the presence and absence of poly(vinyl alcohol) (PVA) to compare the stabilization of catechin for its antioxidant activity. The antioxidant activity of catechin/CD IC nanofibers was also compared to that of the powder form. Scanning electron microscopy (SEM) analysis revealed the production of bead-free nanofibers. The successful incorporation of catechin into nanofibers was confirmed by Fourier-transform infrared spectroscopy (FTIR) analysis of catechin C=C bond stretching. Likewise, H-1 NMR spectroscopic analysis revealed the characteristic aromatic protons of catechin. The formation of inclusion complexes was confirmed by X-ray diffraction (XRD) and dissolution testing by the disappearance of crystalline peaks and rapid fiber dissolution, respectively. Finally, antioxidant testing demonstrated the higher antioxidant activity of polymer-free CD-IC nanofibers.
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    Encapsulation of antioxidant beta-carotene by cyclodextrin complex electrospun nanofibers: Solubilization and stabilization of beta-carotene by cyclodextrins
    (Elsevier Sci Ltd, 2023) Yildiz, Zehra Irem; Topuz, Fuat; Kilic, Mehmet Emin; Durgun, Engin; Uyar, Tamer
    Carotenoids act as effective antioxidant defense systems in humans as they scavenge molecular oxygen and peroxyl radicals. However, their poor water solubility and being susceptible to degradation driven by light and oxygen hinder their bioactivity, therefore, they should be stabilized by host matrices against oxidation. Here, beta-carotene was encapsulated in electrospun cyclodextrin (CD) nanofibers to increase its water-solubility and photostability to enhance its antioxidant bioactivity. beta-carotene/CD complex aqueous solutions were electrospun into nanofibers. The bead-free morphology of the beta-carotene/CD nanofibers was confirmed by SEM. The formation of beta-carotene/CD complexes was explored through computational modeling and experimentally by FTIR, XRD and solubility tests. The antioxidant activity of the fibers exposed to UV irradiation was demonstrated via a free radical scavenger assay, where beta-carotene/CD nanofibers revealed protection against UV radiation. Overall, this work reports the water-borne electrospinning of antioxidant beta-carotene/CD inclusion complex nanofibers, which stabilize the encapsulated beta-carotene against UV-mediated oxidation.
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    Gelatin-Based and Gelatin-Free Electrospun Fibers of Lycopene/Cyclodextrin Inclusion Complexes with Potent Antioxidant Activity
    (Amer Chemical Soc, 2024) Yildiz, Zehra Irem; Topuz, Fuat; Kilic, Mehmet Emin; Durgun, Engin; Uyar, Tamer
    Lycopene, a carotenoid pigment in tomatoes, is used as a dietary supplement with antioxidant effects, but it is vulnerable to environmental factors, such as heat, oxygen, and light. Therefore, there is considerable interest in stabilizing such fragile molecules against environmental influences to preserve their bioactivity during processing and long-term storage. This paper reports the encapsulation and stabilization of lycopene within cyclodextrin (CD) fibers in the presence or absence of gelatin. The successful embedding of lycopene was confirmed by FTIR and NMR analyses. The lycopene's bioactivity could be preserved during processing via electrospinning and long-term storage by stabilizing it against environmental factors. The encapsulated lycopene showed remarkable antioxidant activity, improved thermal stability, and increased UV light stability. The hydrophilic nature of gelatin improved the dissolution of the resulting fibers in water, giving these fibers potential for rapid oral delivery of food-derived molecules encapsulated in fibers.
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    Nanoencapsulation of Menthol/Cyclodextrin Inclusion Complexes in Rapidly Dissolving Electrospun Gelatin Nanofibers
    (Amer Chemical Soc, 2024) Yildiz, Zehra I.; Topuz, Fuat; Aboelkheir, Mahmoud; Kilic, Mehmet Emin; Durgun, Engin; Uyar, Tamer
    Menthol, a minty phytochemical found in peppermint and spearmint plants, is used in various products. However, it may have poor stability, especially when exposed to factors such as light and heat. In this context, this study reports the nanoencapsulation of menthol in electrospun gelatin fibers to improve its stability and release. First, inclusion complexes (ICs) of menthol were prepared with alpha-, beta-, and gamma-cyclodextrins (CDs) and then mixed with gelatin and electrospun into nanofibers. The molecular modeling study showed the inclusion complexation between CDs and menthol. Scanning electron microscopy analysis revealed the formation of a bead-free morphology in gelatin/menthol CD IC fibers. Fourier transform infrared analysis confirmed the presence of menthol in the resulting nanofibers, while H-1 nuclear magnetic resonance spectroscopy determined the menthol content in ICs, which varied between 54 and 100% depending on the CD type. Thermal analysis of the fibers revealed increased stability of menthol in the fibers, which dissolved quickly upon contact with water, suggesting their possible use as fast-dissolving dietary supplements.