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    The Carboxylated Multi-walled Carbon Nanotubes/l-Asparaginase Doped Calcium-Alginate Beads: Structural and Biocatalytic Characterization
    (Springer, 2020) Ulu, Ahmet; Karaman, Muhammet; Yapici, Fatma; Naz, Mehmet; Sayin, Selin; Saygili, Eyup Ilker; Ates, Burhan
    The calcium-alginate/multi-walled carbon nanotube hybrid beads (Ca-ALG/MWCNT-COOH) as a novel kind of matrix were fabricated and characterized in detailed. l-Asparaginase (l-ASNase), which is important chemotherapeutic enzyme-drug in leukemia, was immobilized on the Ca-ALG/MWCNT-COOH hybrid beads. To the best of our knowledge, this is the first study using Ca-ALG/MWCNT-COOH hybrid beads for l-ASNase immobilization. Our characterization investigations displayed that the hybridization between ALG and MWCNT-COOH caused significant changes on the surface morphology and structure. ALG of 0.5% (w/v), CaCl2 of 0.2 M concentration, enzyme of 187.5 U and bead size of 2 mm was found to be best with respect to enzyme loading efficiency. The enzyme was loaded a high yield (97.0%) on these hybrid beads. Remarkably, the tolerance of immobilized enzyme developed towards temperature and pH changes. The maximum activity for the free enzyme was observed at 35 degrees C, pH 7.5, whereas the immobilized enzyme showed maximum activity at 45 degrees C pH 8.5. After immobilization, storage stability of enzyme improved and retained more than 70% of its initial activity after 4 weeks at ~ 30 degrees C as compared with free enzyme which showed only 20% of residual activity. After immobilization, Km value decreased 1.27-fold compared to free counterpart, indicating increased the affinity between the substrate and enzyme. Moreover, immobilized enzyme maintained more than 36% of its original activity even after consecutive 14 reuse. As result, it is worthy of noting that this kind of hybrid materials may become a promising support material for the immobilization of commercial enzymes in areas such as industrial and medical. Graphic
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    Characterization and evaluation of the antimicrobial properties of algal alginate; a potential natural protective for cosmetics
    (Marmara Univ, 2022) Sayin, Selin; Depci, Tolga; Naz, Mehmet; Sezer, Selda; Karaaslan, Merve Goksin; Aras, Aycan; Ugur, Sinem
    Sargassurn vulgare was sampled by free dives in Iskenderun Bay, Hatay, Turkey, in September 2018. Sargassum vulgare is a material with high economic value because it has compounds that can be used in medical applications such as alginic acid and at the same time it contains carbohydrates and vitamins. Alginates were extracted with a sequential extraction protocol from Sargassum vulgare. Structural characterization of alginate obtained from Sargassum vulgare was determined by FT-IR spectrum, phase structure by XRD diffractometer, and surface morphology by SEM image. Within the scope of the study, alginate obtained from Sargassurn vulgare and herbal preservative 705 used in the field of cosmetics were compared. After pretreatment of Sargassurn vulgare with ethanol, alginate extraction was performed. Microorganisms of Pseudontonas aeruginosa, Staphylococcus aureus, Candida albicans, Escherichia soli, Aspergillus brasiliensis were used to examine the antimicrobial activity of the obtained alginate and showed that the contamination risk was tolerable for all microorganisms examined on the seventh day of incubation. Alginate obtained from Sargassum vulgare was found to be more effective than herbal preservative 705 at 0 hours. Pseudomonas aeruginosa, Staphylococcus aureus are microorganisms with the highest effect in the 0 hour. Since alginate obtained from Sargassurn vulgare is more effective on microorganisms in a shorter time than herbal preservative 705, it is predicted that it can be a product that can be used in the field of cosmetics.