Browsing by Author "Aytac, Z."
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Item Open Access Antioxidant α-tocopherol/γ-cyclodextrin–inclusion complex encapsulated poly(lactic acid) electrospun nanofibrous web for food packaging(John Wiley and Sons Inc., 2017-01) Aytac, Z.; Keskin, N. O. S.; Tekinay, T.; Uyar, Tamerα-Tocopherol (α-TC) and α-TC/cyclodextrin (CD)–inclusion complex (IC) incorporated electrospun poly(lactic acid) (PLA) nanofibers (NF) were developed via electrospinning (PLA/α-TC–NF and PLA/α-TC/γ-CD–IC–NF). The release of α-TC into 95% ethanol (fatty food simulant) was much greater from PLA/α-TC/γ-CD–IC–NF than from PLA/α-TC–NF because of the solubility increase in α-TC; this was confirmed by a phase-solubility diagram. 2,2-Diphenyl-1-picrylhydrazyl radical-scavenging assay shows that PLA/α-TC–NF and PLA/α-TC/γ-CD–IC–NF had 97% antioxidant activities; this value was expected to be high enough to inhibit lipid oxidation. PLA/α-TC–NF and PLA/α-TC/γ-CD–IC–NF were tested directly on beef with the thiobarbituric acid reactive substance (TBARS) method, and the nanofibers displayed a lower TBARS content than the unpackaged meat sample. Thus, active packaging significantly enhanced the oxidative stability of the meat samples at 4 °C. In conclusion, PLA/α-TC/γ-CD–IC–NF was shown to be promising as an active food-packaging material for prolonging the shelf life of foods.Item Open Access Functional polymeric nanofibers via electrospinning(2012) Uyar, T.; Kayacı, F.; Celebioglu, A.; Aytac, Z.; Ertas, Y.Item Open Access pH-responsive nanofibers with controlled drug release properties(Royal Society of Chemistry, 2014-12-02) Demirci, S.; Celebioglu A.; Aytac, Z.; Uyar, TamerSmart polymers and nanofibers are potentially intriguing materials for controlled release of bioactive agents. This work describes a new class of pH responsive nanofibers for drug delivery systems with controlled release properties. Initially, poly(4-vinylbenzoic acid-co-(ar-vinylbenzyl) trimethylammonium chloride) [poly(VBA-co-VBTAC)] was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Then, ciprofloxacin was chosen as the model drug for the release study and encapsulated into pH-responsive polymeric carriers of poly(VBA-co-VBTAC) nanofibers via electrospinning. The morphology of the electrospun nanofibers was examined by scanning electron microscopy (SEM). The structural characteristics of the pH responsive nanofibers were investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The release measurements of ciprofloxacin from pH responsive nanofibers were also performed by high-performance liquid chromatography (HPLC) analysis. To show the pH sensitivity of these nanofibers, the release profile of ciprofloxacin was examined under acidic, neutral and basic conditions. The results indicate that pH responsive nanofibers can serve as effective drug carriers since the release of ciprofloxacin could be controlled by changing the pH of the environment, and therefore these drug loaded pH-responsive nanofibers might have potential applications in the biomedical field. This journal is © The Royal Society of Chemistry.Item Open Access Polylactic acid (PLA)/Silver-NP/VitaminE bionanocomposite electrospun nanofibers with antibacterial and antioxidant activity(Springer, 2014-10) Munteanu, B. S.; Aytac, Z.; Pricope, G. M.; Uyar, Tamer; Vasile, C.The antibacterial property of silver nanoparticles (Ag-NPs) and the antioxidant activity of Vitamin E have been combined by incorporation of these two active components within polylactic acid (PLA) nanofibers via electrospinning (PLA/Ag-NP/VitaminE nanofibers). The morphological and structural characterizations of PLA/Ag-NP/VitaminE nanofibers were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and X-ray diffraction. The average fiber diameter was 140 ± 60 nm, and the size of the Ag-NP was 2.7 ± 1.5 nm. PLA/Ag-NP/VitaminE nanofibers inhibited growth of Escherichia coli, Listeria monocytogenes and Salmonella typhymurium up to 100 %. The amount of released Ag ions from the nanofibers immersed in aqueous solution was determined by Inductively Coupled Plasma Mass Spectrometry, and it has been observed that the release of Ag ions was kept approximately constant after 10 days of immersion. The antioxidant activity of PLA/Ag-NP/VitaminE nanofibers was evaluated according to DPPH (2,2-diphenyl-1-picrylhydrazyl) method and determined as 94 %. The results of the tests on fresh apple and apple juice indicated that the PLA/Ag/VitaminE nanofiber membrane actively reduced the polyphenol oxidase activity. The multifunctional electrospun PLA nanofibers incorporating Ag-NP and Vitamin E may be quite applicable in food packaging due to the extremely large surface area of nanofibers along with antibacterial and antioxidant activities. These materials could find application in food industry as a potential preservative packaging for fruits and juices.Item Open Access Sulfisoxazole/cyclodextrin inclusion complex incorporated in electrospun hydroxypropyl cellulose nanofibers as drug delivery system(Elsevier, 2015-04-01) Aytac, Z.; Sen, H. S.; Durgun, Engin; Uyar, TamerHerein, hydroxypropyl-beta-cyclodextrin (HPCD) inclusion complex (IC) of a hydrophobic drug, sul- fisoxazole (SFS) was incorporated in hydroxypropyl cellulose (HPC) nanofibers (HPC/SFS/HPCD-IC-NF) via electrospinning. SFS/HPCD-IC was characterized by DSC to investigate the formation of inclusion complex and the stoichiometry of the complex was determined by Job’s plot. Modeling studies were also performed on SFS/HPCD-IC using ab initio technique. SEM images depicted the defect free uniform fibers and confirmed the incorporation of SFS/HPCD-IC in nanofibers did not alter the fiber morphology. XRD analyses showed amorphous distribution of SFS/HPCD-IC in the fiber mat. Release studies were performed in phosphate buffered saline (PBS). The results suggest higher amount of SFS released from HPC/SFS/HPCD-IC-NF when compared to free SFS containing HPC nanofibers (HPC/SFS-NF). This was attributed to the increased solubility of SFS by inclusion complexation. Sandwich configurations were prepared by placing HPC/SFS/HPCD-IC-NF between electrospun PCL nanofibrous mat (PCL-HPC/SFS/HPCD-IC-NF). Consequently, PCL-HPC/SFS/HPCD-IC-NF exhibited slower release of SFS as compared with HPC/SFS/HPCD-IC-NF. This study may provide more efficient future strategies for developing delivery systems of hydrophobic drugs.Item Open Access Surface modification of electrospun polyester nanofibers with cyclodextrin polymer for the removal of phenanthrene from aqueous solution(Elsevier, 2013) Kayaci, F.; Aytac, Z.; Uyar, TamerSurface modified electrospun polyester (PET) nanofibers with cyclodextrin polymer (CDP) were produced (PET/CDP). CDP formation onto electrospun PET nanofibers was achieved by polymerization between citric acid (CTR, crosslinking agent) and cyclodextrin (CD). Three different types of native CD (α-CD, β-CD and γ-CD) were used to form CDP. Water-insoluble crosslinked CDP coating was permanently adhered onto the PET nanofibers. SEM imaging indicated that the nanofibrous structure of PET mats was preserved after CDP surface modification process. PET/CDP nanofibers have shown rougher/irregular surface and larger fiber diameter when compared to untreated PET nanofibers. The surface analyses of PET/CDP nanofibers by XPS elucidated that CDP was present on the fiber surface. DMA analyses revealed the enhanced mechanical properties for PET/CDP where PET/CDP nanofibers have shown higher storage modulus and higher glass transition temperature compared to untreated PET nanofibers. The surface area of the PET/CDP nanofibers investigated by BET measurements showed slight decrease due to the presence of CDP coating compared to pristine PET nanofibers. Yet, it was observed that PET/CDP nanofibers were more efficient for the removal of phenanthrene as a model polycyclic aromatic hydrocarbon (PAH) from aqueous solution when compared to pristine PET nanofibers. Our findings suggested that PET/CDP nanofibers can be a very good candidate as a filter material for water purification and waste treatment owing to their very large surface area as well as inclusion complexation capability of surface associated CDP. © 2013 Elsevier B.V.