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    Magnetic-propelled Fe3O4-chitosan carriers enhance l-asparaginase catalytic activity: a promising strategy for enzyme immobilization
    (Royal Soc Chemistry, 2018) Ates, Burhan; Ulu, Ahmet; Koytepe, Suleyman; Ali Noma, Samir Abbas; Kolat, Veli Serkan; Izgi, Tekin
    Magnetic-propelled carriers comprising magnetic Fe3O4-chitosan nanoparticles were immobilized with l-asparaginase (l-ASNase). The enzyme displayed enhanced catalytic activity in a weak magnetic field, and thermal and pH stabilities. The conjugated l-ASNase presented higher thermostability and wider range of pH stability in comparison with those of free l-ASNase. Moreover, the reusability of conjugated l-ASNase significantly improved after immobilization and it retained 60.5% of its initial activity after undergoing 16 cycles. The conjugated l-ASNase maintained more than 50% and 48% initial activity after 4 weeks of storage at 4 degrees C and room temperature, respectively. Furthermore, we reveal that the activity of conjugated l-ASNase onto magnetic Fe3O4-chitosan particles increased by about 3-fold in the weak magnetic field at certain frequencies and flux density compared with that of free l-ASNase. Considering these excellent attributes, the magnetic-propelled mechanism in the transporting and activation of l-ASNase can be used by enhancing the catalytic activity, stability, and efficiency in vital implications for medicinal biotechnology.
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    The preparation of trimethylolpropane ethoxylate-170-based antibacterial wound dressing materials containing allantoin via electrospinning method
    (Springer, 2024) Cakmen, Ayse Basak; Ali Noma, Samir Abbas; Gurses, Canbolat; Koytepe, Sueleyman; Ates, Burhan; Yilmaz, Ismet
    In this study, multifunctional wound and burn dressing material was developed to cover open wounds and protect them from external effects. Trimethylolpropane ethoxylate-170 (TMPE)-based polyurethane/polycaprolactone (PU/PCL) dressing materials were prepared with high biocompatibility and ordered nanofiber formation. Prepared PU/PCL dressing materials also contain allantoin additive to accelerate wound healing. Polyurethane structures were synthesized using solution polymerization technique from hexamethylene diisocyanate, polyethylene glycol-200, TMPE and Tween-40 monomers in different mole ratios. The obtained polyurethanes and dressing materials were characterized structurally, thermally and morphologically. Then, PCL, allantoin and gentamicin sulfate were added to these PU structures and converted into wound dressing materials by electrospinning technique. The allantoin release, mechanical analysis, antibacterial properties and biodegradability of the produced dressing materials were investigated. The obtained PU/PCL dressing materials were seen as flexible, durable and structural stable. These dressing materials have fiber diameter of approximately 500 nm. The tensile strength and Young's modulus of PU/PCL dressing materials are 2.22 +/- 0.39 MPa and 1.04 +/- 0.11 MPa. They released allantoin regularly for about 70 h and showed antibacterial properties. In addition, the prepared dressing materials have grade 1 biocompatibility. As a result, these dressing materials provide a good alternative to existing wound dressing materials.