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    Ammonia-responsive thermoplastic starch films incorporated with gallic acid-cobalt metal-organic frameworks (GA/Co-MOF) for real-time tracking of shrimp freshness
    (Elsevier, 2026) Yilmaz, Mustafa Tahsin; Parlak, Mahmut Ekrem; Uzuner, Kubra; Yildiz, Zehra Irem; Dundar, Ayse Neslihan; Sahin, Oya Irmak; Saricaoglu, Furkan Turker
    Developing ammonia-responsive biopolymer-based smart films with strong mechanical properties and reliable visual freshness indicators is a significant research focus. Integrating cobalt-based metal-organic frameworks (CoMOF) into a polymer matrix is a contemporary method for manufacturing intelligent packaging materials, primarily due to their rapid responsiveness to ammonia. This study successfully synthesized an ammonia-sensitive Co-MOF by using gallic acid as the ligand (GA/Co-MOF) and integrated them into a thermoplastic starch (TPS) matrix, creating high-performance, multifunctional TPS-based intelligent active composite films (TPS/Co-MOF). FTIR analysis indicates that cobalt exhibits a strong affinity for the carboxy and hydroxy groups of gallic acid, leading to the formation of spherical aggregates, which have diameters of between 600 and 1000 nm, as visualized using SEM. A thorough analysis assessed the impact of GA/Co-MOF on the films' physicochemical, water barrier, and morphological properties, as well as their color, optical, UV-blocking, and material characteristics (thermal, crystallographic, molecular, and mechanical) and ammonia-responsive performances. The GA/Co-MOF nanofillers were uniformly dispersed in the TPS matrix, significantly enhancing tensile strength (from 4.35 to 5.29 MPa), elongation at break (from 122.97 to 153.7 %), puncture force (from 612.78 to 1069.96 g), puncture deformation (from 3.78 to 4.87 mm), water resistance, and UV-blocking abilities. Additionally, the films exhibited improved thermal stability, toughness, elasticity, and ammonia-sensitive discoloration properties. Notably, the TPS/Co-MOF films enabled effective real-time visual monitoring of shrimp freshness, with a faster color response time than existing nanocomposite films, making them promising for active and intelligent food packaging. These findings highlight the significant potential of TPS/Co-MOF films to meet the demands of safe packaging solutions with superior mechanical performance and freshness monitoring.
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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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    Encapsulation of carvacrol in (3-cyclodextrin metal-organic frameworks: Improved solubility, stability, antioxidant capacity and controlled release of carvacrol
    (Elsevier Sci Ltd, 2025) Ates, Kivilcim; Yildiz, Zehra Irem
    Carvacrol, a phenolic compound found in oregano and thyme, exhibits potent antioxidant activity and is commonly utilized in food applications due to its flavor and fragrance, as well as its capacity to inhibit oxidation and prolong shelf life. However, its application is limited by its low water solubility, low stability and high volatility. This study examines the encapsulation of carvacrol within edible and porous materials, namely cyclodextrin metal-organic frameworks (CD-MOFs), as a means of enhancing its properties. In the present study, (3-CD-MOFs were synthesized with varying amounts of carvacrol. The encapsulation efficiency was observed to vary with the ratio of carvacrol to (3-CD-MOF, with an improvement in efficiency achieved at higher ratios up to a point, reflecting the capacity of the (3-CD-MOF to encapsulate carvacrol molecules effectively before reaching saturation. Morphological examination and X-ray diffraction (XRD) revealed significant structural alterations in the (3-CD-MOF following the loading of carvacrol. Fourier-transform infrared (FTIR) spectroscopy served to confirm the successful encapsulation, as evidenced by alterations in the bonding patterns. Thermal analysis revealed shifts in degradation temperatures and the absence of the boiling point peak of carvacrol in carvacrolloaded (3-CD-MOFs (Car/(3-CD-MOFs), indicative of successful encapsulation and enhanced thermal stability. The antioxidant capacity of carvacrol was found to increase significantly upon encapsulation within (3-CD-MOFs, as evidenced by antioxidant assays. Solubility and release profile studies demonstrated an improvement in the dissolution and controlled release behavior of carvacrol. These findings collectively highlight the potential of (3-CD-MOFs as effective carriers for enhancing the functional properties and applications of carvacrol.
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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.