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Öğe Adsorption of Bisphenol A onto β-Cyclodextrin-Based Nanosponges and Innovative Supercritical Green Regeneration of the Sustainable Adsorbent(MDPI, 2025) Salgin, Ugur; Alomari, Ismail; Soyer, Nagihan; Salgin, SemaBisphenol A is a widely recognized endocrine disruptor that persists in ecosystems, harms aquatic organisms, and contributes to ecological degradation, raising global environmental concerns. Numerous studies have explored beta-cyclodextrin-based adsorbents for Bisphenol A removal; however, their regeneration remains a major challenge, often relying on energy-intensive processes and excessive use of organic solvents. In this study, Bisphenol A was selected as a model pollutant, and its adsorption onto beta-cyclodextrin nanosponges was investigated. After adsorption, Bisphenol A was efficiently recovered from the saturated beta-cyclodextrin nanosponges using an innovative and sustainable supercritical CO2-based green process, which simultaneously regenerated the adsorbent. The adsorption process achieved an efficiency of 95.51 +/- 0.82% under optimized conditions (C-0 = 150 mg/L, m(beta-CDNS) = 0.15 g, T = 25 degrees C, and N = 200 rpm), with a maximum adsorption capacity of 47.75 +/- 0.28 mg/g. The regeneration process achieved over 99% efficiency at 60 degrees C and 300 bar, with 10% (v/v) ethanol as a co-solvent, nearly fully restoring the adsorbent's performance. Unlike conventional regeneration techniques, this green approach eliminates the need for environmentally harmful organic solvents while preserving the adsorbent's structural integrity, making it a highly efficient and sustainable alternative. This study is the first to demonstrate the effective application of supercritical CO2-based regeneration for beta-cyclodextrin nanosponges in Bisphenol A removal, providing a scalable and environmentally sustainable solution for wastewater treatment. Furthermore, characterization analyses confirmed that the adsorbent retained its chemical and morphological stability after adsorption and regeneration.Öğe Antidepresan fluoxetıne karışımının enantiyomerik ayrılmasına kiral selektör etkisi(Cumhuriyet Üniversitesi, 2012) Soyer, Nagihan; Salgın, SemaBirçok ilaç ve tat verici bileşikler fiziksel ve kimyasal özellikleri oldukça benzer olan kiral izomerlerden oluşmuş rasemik karışımlardır. Farmasötik endüstrisinde, bir enantiyomer istenen terapötik aktiviteyi gösterirken diğeri aktif olmayan formda olabilir veya istenmeyen yan etkileri gösterebilir. Son yıllarda, rasemik karışımların enantiyomerlerine ayrılması farmasötik endüstrisinde, gıda hazırlamada, zirai kimyasallar ve parfüm üretimi gibi alanlarda oldukça ilgi çekmektedir. Saf enantiyomerler elde etmek için temel yollar asimetrik sentez ve rasematların rezolüsyonudur. Kimyasal kinetik rezolüsyon, enzimatik kinetik rezolüsyon, diastereomer kristalizasyon, kromatografi ve membranlar gibi kiral ayırma teknolojileri arasında membran prosesleri ekonomik ve ekolojik açıdan diğer klasik kiral ayırma metotları ile rekabet etmektedir. Membran ayırma teknolojisi ılımlı koşullar altında sürekli işletilebilir olması ve ölçek büyütme basamağının diğer klasik yöntemlere göre daha kolay olması avantajdır.Depresyon tedavisi için fluoxetine'in tek enantiyomer formülasyonunu geliştirme çalışmaları başarısızlıkla sonuçlanmıştır. Literatürde bu ilaç karışımının ayrılması ile ilgili az sayıda çalışma vardır ve bu çalışmalarda enantiyomerik ayırma için kromatografi ve elektroforez yöntemleri kullanılmıştır. Dolayısı ile kiral membranlar ile rasemik ilaç fluoxetine'in ayrılması ilk defa bu yüksek lisans tez çalışmasında gerçekleştirilmiştir.Bu yüksek lisans tez çalışmasında ?-siklodekstrin, lipaz ve BSA gibi farklı kiral selektörler kullanılarak antidepresan rasemik fluoxetine karışımının ayrılması için kiral seçici membranlar geliştirilmiştir. Seçilen kiral selektörler 30 kDa PES membrana farklı pH ve tuz derişim değerlerinde statik adsorpsiyon, dinamik adsorpsiyon ve çapraz bağlama yöntemleri ile bağlanmıştır. Modifiye edilen membranların ayırma performansı ultrafiltrasyon hücresi kullanılarak incelenmiştir. Rasemik fluoxetine ve enantiyomerlerinin analizi kiral kolon kullanılarak HPLC sisteminde incelenmiştir. Farklı yöntemlerle kiral selektör bağlanmasından sonra kiral selektör bağlanma konumları ve membran yüzeyindeki değişimler FTIR-ATR ile belirlenmiştir. Membranların zeta potansiyelleri akım potansiyeli ölçümüne dayanan elektrokinetik analiz (EKA) ile ölçülmüştür. Kiral selektörlerin yük analizleri Zetasizer NanoZS cihazı ile yapılmıştır.Öğe Effect of Reaction Parameters on the Synthesis of Cyclodextrin-Based Nanostructured Polymers for Drug Delivery(MDPI, 2025) Salgin, Sema; Eke, Hasan Huseyin; Soyer, Nagihan; Salgin, UgurIn this study, cyclodextrin-based nanostructures (CDNSs) were synthesized through the cross-linking of cyclodextrin (CD) with epichlorohydrin (ECH) as a cross-linker. Two types of CDNSs, alpha-CDNS and beta-CDNS, were prepared to systematically investigate the influence of reaction parameters-such as the solubilization time of alpha-CD and beta-CD, the molar ratio of ECH to CD, and NaOH concentration-on the physicochemical properties of the final product. Naproxen (NAP), a poorly water-soluble drug, was selected as a model compound to assess the drug-loading capacity of the synthesized CDNSs. The effect of each reaction parameter on NAP integration into the CDNSs was examined at varying weight ratios. The optimal reaction conditions were determined to be a solubilization time of 6 h, an ECH/CD molar ratio of 8/1, and an NaOH concentration of 33%. Under these conditions, the NAP loading efficiency of alpha-CDNSs was calculated as 67.12%. Comparative analysis revealed that alpha-CDNSs outperformed beta-CDNSs in terms of drug-loading capacity. Additionally, the synthesized CDNSs and NAP-loaded CDNSs were characterized using FTIR, DSC, XRD, SEM, and Zetasizer analyses, while the NAP concentration was determined by HPLC.Öğe Enantiomeric separation of fluoxetine in ultrafiltration through chiral selector-immobilized polyethersulfone membranes(ELSEVIER SCIENCE BV, 2012) Soyer, Nagihan; Salgin, Sema; Salgin, Ugur…Öğe Investigation of magnetic iron oxide nanoparticle properties with co-precipitation methods under different reaction conditions(Bentham Science Publishers, 2021) Salgın, Sema; Salgın, Uğur; Soyer, NagihanObjective: In this study, magnetic iron oxide nanoparticles were synthesized by cost effective and an easy co-precipitation method. Methods: The effects of reaction parameters such as the mole ratio of Fe2+/Fe3+ (1/1, 1/2 and 1/3) and the base type (NaOH and NH4OH) on the average hydrodynamic diameter, zeta potential, chemical and morphological structure and saturation magnetization values of magnetic iron oxide nanoparticles were systematically investigated. Results: Magnetic iron oxide nanoparticles synthesized at the mole ratio of 1/2 using NH4OH base gave better results in terms of particle size and particle shape, magnetization value. Conclusion: In order to prevent the formation of different phases in the co-precipitation method, an alternative approach was developed and the reaction was performed using inert supercritical CO2 atmosphere. © 2021 Bentham Science Publishers.Öğe Streaming Potential Measurements of Polyethersulfone Ultrafiltration Membranes to Determine Salt Effects on Membrane Zeta Potential(ESG, 2013) Salgin, Sema; Salgin, Ugur; Soyer, NagihanA systematic study on the zeta potential of polyethersulfone membranes determined by streaming potential measurements was made to examine various salt effects. Chloride salts; KCl, NaCl, CaCl2 and MgCl2 and potassium salts; KCl, KNO3, KClO3, K2CO3, K2SO4 and K2Cr2O7 were used to investigate the effects of cations and anions on the zeta potential of membranes, respectively. The zeta potential was obtained in 0.001 M salt solutions at the range of pH=4.0-8.0. The effect of ionic strength on membrane zeta potential was also investigated in the solution of KC1 and Na2HPO4 with 0.001 M-0.1 M salt concentrations. At high pH values, anion adsorption on membrane surface had a more potent effect on zeta potential, while at low pH values, cation adsorption to membrane surface also possessed more potent effect on zeta potential. In general, zeta potential decreased with increasing ionic strength due to the compression of electrical double layer. However, preferential adsorption of ions on the membrane surface is another important parameter affecting zeta potential beside the ionic strength. The influence of ionic strength on the membrane zeta potential can be observed by performing FTIR-ATR analysis.Öğe Thermodynamic and Structural Properties of Biomimetic Monolayers Containing Cholesterol and Magnetite Nanoparticles(Uğur ŞEN, 2025) Soyer, Nagihan; Salgın, Sema; Salgın, UğurThe thermodynamic and structural properties of biomimetic monolayers composed of cholesterol, dipalmitoylphosphatidylcholine, and hydrophobic magnetite (Fe₃O₄) nanoparticles were investigated under varying cholesterol molar fractions and pH conditions (4.8 and 7.4). Langmuir monolayer experiments were performed to analyze surface pressure-area isotherms, excess molecular area, excess Gibbs free energy of mixing, and compressibility modulus to assess lipid monolayer phase behavior, molecular organization, and mechanical stability. The results confirm that cholesterol enhances monolayer condensation up to a cholesterol molar fraction of 0.50, particularly at pH 7.4, where stronger lipid-lipid interactions promote molecular ordering and increase monolayer rigidity. At cholesterol molar fractions of 0.75 and higher, steric hindrance and phase separation effects emerge, disrupting monolayer homogeneity. pH significantly influences monolayer stability, with pH 7.4 favoring lipid condensation, whereas pH 4.8 induces monolayer expansion and molecular disorder. Excess molecular area and Gibbs free energy of mixing analyses indicate the strongest cholesterol-lipid interactions at a cholesterol molar fraction of 0.25 for pH 4.8 and 0.50 for pH 7.4, confirming these compositions as the most thermodynamically stable. Compressibility modulus analysis demonstrates that cholesterol enhances monolayer rigidity, with pH 7.4 producing higher values. However, at high cholesterol molar fractions, compressibility modules slightly decrease, suggesting steric constraints and lateral phase separation. The incorporation of magnetite nanoparticles increases molecular area and slightly reduces monolayer rigidity at low cholesterol molar fractions due to steric disruptions, but at cholesterol molar fractions of 0.50 and higher, cholesterol stabilizes the monolayer, counteracting nanoparticle-induced perturbations. These findings provide insight into the thermodynamic and structural regulation of biomimetic lipid monolayers by cholesterol and magnetite nanoparticles, with implications for nanomedicine, membrane biophysics, and lipid-based nanostructures.
