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    Preparation and Characterization of Biopolymeric Hybrid Microbeads for Controlled Drug Delivery of Levothyroxine Sodium
    (Springer Heidelberg, 2024) Cakmak, Funda; Ozcan, Yusuf; Sokmen, Bugra; Gok, Cem; Fenkci, Semin Melahat
    The active ingredient levothyroxine sodium is used in diseases originating from the thyroid gland or in the treatment of functional disorders of the thyroid gland. Since this situation will cause problems related to patient compliance, the development of long-lasting formulations to treat hypothyroidism would greatly help with solving this problem. In the study, hybrid microbeads in gel form which increases both patient compliance and the effectiveness of the drug, were proposed as a controlled oral delivery vehicle for levothyroxine sodium. Four formulations, both non-medicated and medicated were prepared using different compositions including agar, gum arabic, kaolin clay, graphene oxide, and glycerol. The microbeads were characterized by various methods to obtain information on the surface topography, composition of the material, and physical properties. Comparing the release rates of medicated hybrid microbeads for in vitro pH 1.5 and pH 7.4 environments, they performed a slower and more controlled drug release. A value of n of the dry form of the hybrid microbeads doped with kaolin clay and loaded with levothyroxine sodium (K4) less than 0.5 indicates that the emissions are compatible with the quasi-Fickian diffusion mechanism. Therefore, the slowest drug release was obtained in K4. When the release kinetics of K4 were examined, 20%, 56%, and 83% drug release were observed in 2, 4, and 5 h, respectively.
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    Preparation of new alginate capsules enclosing diatomite and organic extractants to uptake lanthanum
    (Elsevier, 2023) Colakoglu, Tunc; Oral, Alparslan Enes; Aytas, Sule; Yusan, Sabriye; Kaptanoglu, Ikbal Gozde; Gok, Cem; Yoho, Michael Duncan
    The present study conducted syntheses of Ca-alginate composite beads, which involved trioctyl-amine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) organic extractants, and diatomite for separation of La (III) ions from dilute aqueous solutions. The surface morphology of the capsules was examined under Scanning Electron Microscopy, while their chemical structure was characterized using Fourier Transform Infrared Spectroscopy. Alginate composites were prepared by adding concentrations of TBP (1%-10%), TOPO (0.005 M-0.09 M) and TOA (1%-10%) organic extractants to the Na-alginate-diatomite mixture.The effects of various parameters on adsorption such as solution pH, contact time, metal ion concentration, and temperature, were individually tested using standard solutions of La(III). The maximum uptake capacity of the alginate composite adsorbent, consisting of TOA, diatomite, and alginate for La(III) ions, was examined at 25 degrees C. Adsorption data were analyzed using Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, FloryHuggins and Brunauer, and Emmett and Teller (BET) isotherm models. The biosorption isotherm parameters were estimated by both linear and nonlinear regression analyses. The results indicate that the Langmuir model provides a better fit than the other models for the adsorption equilibrium data.Thermodynamic parameters such as variations of enthalpy, entropy, and Gibbs free energy were calculated. The maximum uptake capacity of the alginate composite adsorbent, including TOA, diatomite, and alginate for La(III) ions from aqueous solutions was found to be 146.4 mg/g. The adsorption efficiency in dilute solutions was determined to be 97.2%.
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    Sustainable Production of Microcrystalline and Nanocrystalline Cellulose from Textile Waste Using HCl and NaOH/Urea Treatment
    (MDPI, 2025) Isitan, Arzum; Pasquardini, Laura; Bersani, Massimo; Gok, Cem; Fioravanti, Simona; Lunelli, Lorenzo; Caglarer, Evren
    Bio-nanomaterials are gaining increasing attention due to their renewable and eco-friendly characteristics. Among these, nanocrystalline cellulose (NCC) stands out as one of the most advanced materials for applications in food, healthcare, composite production, and beyond. In this study, NCC was successfully extracted from cotton-based textile waste using a combination of chemical and mechanical methods. The cellulose fibers were first hydrolyzed using a dilute HCl solution, neutralized, and then dried, resulting in microcrystalline cellulose (MCC) with diameters ranging from 7 to 15 mu m and lengths up to 300 mu m (as observed via optical microscopy and scanning electron microscopy, SEM). To achieve nanoscale dimensions, NaOH/urea solution with mechanical treatment was applied, resulting in the successful extraction of NCC in the supernatant, particularly under room-temperature conditions. Dynamic light scattering (DLS) analysis confirmed the presence of nanostructures (average sizes ranging from 120 nm to 750 nm), and atomic force microscopy (AFM) analysis verified the nanoscale range (diameters between 2 and 4 nm and lengths from 200 nm to 1 mu m). Fourier transform infrared (FTIR) spectroscopy revealed the conversion of cellulose I to cellulose II, confirming the successful transformation into NCC. For the first time, NCC was obtained from undyed cotton textile wastes using NaOH/urea treatment after HCl hydrolysis, eliminating the need for pre-treatment and intermediate steps.