Person: TOKSOY ÖNER, EBRU
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TOKSOY ÖNER
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Publication Open Access Synthesis and characterization of interpenetrating network (IPN) based levan-polyacrylamide hydrogels and their application in conservation of cultural heritage(2023-11-01) ÜNAL YILDIRIM, SEMRA; OKTAR, FAİK NÜZHET; GENÇ, SEVAL; TOKSOY ÖNER, EBRU; Özen Sağlam R., Ünal Yıldırım S., Oktar F. N., Genç S., Erdem G., Toksoy Öner E.In this study, an IPN based enzymatic levan-polyacrylamide hydrogel (EL-PA) was developed and characterized for its structural, morphological, rheological properties and swelling kinetics to underline hydrogel properties and its potential use in paper conservation. The addition of levan also led to changes in the viscoelastic behavior of the hydrogels, with the complex viscosity of EL-PA samples showing pronounced dependence on shear rate. The swelling and the overall surface area of the hydrogels were increased with the addition of levan into the polymer network. Source associated structural differences were found to be negligible such that both microbially produced linear and enzymatically produced branched forms of levan performed equally well. Solvent loaded hydrogels were then applied on an artifact, a 19th century book of Namık Kemal, and investigated using FTIR, SEM, XRD and colorimetric analysis. Old adhesive layers were successfully removed, and hydrogels showed good compatibility and ease of application. This study has shown that levan has improved hydrogel properties and levan based systems bear high potential in conservation science.Publication Open Access Biosynthesis of Levan by Halomonas elongata 153B: Optimization for Enhanced Production and Potential Biological Activities for Pharmaceutical Field(2022-01-01) TOKSOY ÖNER, EBRU; Erdal Altıntaş Ö., TOKSOY ÖNER E., ÇABUK A., AYTAR ÇELİK P.Halophilic organisms are a novel attractive option as cell factories for the production of industrially valuable bioproducts. Halomonas elongata is the cell factory of choice for ectoine production, but its levan production has not been well researched. Based on this scientifc motivation, in this study, we evaluated the chemical and biological properties of levan produced by the halophilic extremophile Halomonas elongata 153B (HeL). First, the central composite design was used to determine the optimal process variables for maximum levan biosynthesis. Then, the levan produced from HeL was purifed, quantifed, and chemically characterized with FTIR, 1 H-NMR, and GPC analyses. This was followed by antioxidant, anti-infammatory, antibioflm, and antimicrobial activity tests to assess its biological activities as well as a cytotoxcity assay. Maximum levan yields of 5.13±0.38 g/L were achieved after dialysis at the optimum levels of process variables. The 1 H-NMR spectrum of HeL revealed characteristic signals. It showed a strong antioxidant activity of 67.88% and the best radical scavenger. At a concentration of 400 µg/mL, HeL showed the most anti-infammatory efcacy. Also, at all indicated concentrations (250, 500, 750, and 1000 μg/mL) HeL, acted against bioflms formed by Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 11778, Candida albicans ATCC 10231. Furthermore, HeL displayed antimicrobial activities against all strains tested. Finally, HeL showed high Cell viability in all dosages and no cytotoxicity was observed. In light of these results, HeL may have high potential in the medical, pharmaceutical and dermo-cosmetics industries.Publication Metadata only The book of fructans(Elsevier Science, Oxford/Amsterdam , 2023-03-01) TOKSOY ÖNER, EBRU; Toksoy Öner E. (Editör), Van Den Ende W. (Editör)After more than 30 years, The Book of Fructans represents the first and most comprehensive coverage of fructans generated by pioneer glycoscientists from the field. It outlines the fundamentals of all fructan types, their terminology, chemical and structural-functional features, biosynthetic enzymes that make and break them, their presence and possible roles in nature, their evolutionary aspects and their microbial, enzymatic, and plant-based production. Additional sections cover the applications of fructans, specifically, the agro/chemical and biomedical applications, health, pharmaceutical and cosmetic applications, fructans in food and feed, fructan nanotechnology, the immunomodulatory and antiviral effects of fructans and the perspectives for fructans in circular economies and sustainable societies. Intended for scientists, entrepreneurs, academicians and students working in related fields, this book will be a useful resource for all who wish to learn more about these extraordinary carbohydrates.Publication Metadata only Levan micro/nano particulate systems for controlled cargo delivery(2021-02-19) CESUR, SÜMEYYE; GÜNDÜZ, OĞUZHAN; TOKSOY ÖNER, EBRU; Cinan E., Santos S., Cesur S., Gündüz O., Mono J., Toksoy Öner E.Publication Metadata only Controlled release of resveratrol-loaded levan nanoparticles using electrospray(2021-06-26) CESUR, SÜMEYYE; GÜNDÜZ, OĞUZHAN; TOKSOY ÖNER, EBRU; Cinan E., Cesur S., Gündüz O., Toksoy Öner E.