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    Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties
    (Elsevier, 2016) Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa
    A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90 degrees C for 2 h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5 degrees C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro. (C) 2015 Elsevier B.V. All rights reserved.
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    Synthesis, characterization and modification of Gum Arabic microgels for hemocompatibility and antimicrobial studies
    (Elsevier Sci Ltd, 2017) Farooq, Muhammad; Sagbas, Selin; Sahiner, Mehtap; Siddiq, Mohammad; Turk, Mustafa; Aktas, Nahit; Sahiner, Nurettin
    Gum Arabic (GA) microgels were successfully prepared via reverse micellization method with high yield (78.5 +/- 5.0%) in 5-100 mu m size range using divinyl sulfone (DVS) as a crosslinker. The GA microgels were degraded hydrolytically 22.8 +/- 3.5% at pH 1 in 20 days, whereas no degradation was observed at pH 7.4 and pH 9 at 37 degrees C. By using diethylenetriamine (DETA), and taurine (TA) as chemical modifying agents, GA microgels were chemically modified as GA-DETA and GA-TA, and the zeta potential values of 5.2 +/- 4.1 and -24.8 +/- 1.3 mV were measured, respectively in comparison to -27.3 +/- 4.2 mV for GA. Moreover, blood compatibility of GA, GA-TA, and GA-DETA microgels was tested via in vitro protein adsorption, % hemolysis ratio, and blood clotting index. All the microgels were hemocompatible with% hemolysis ratio between 0.23 to 2.05, and the GA microgels were found to be highly compatible with a blood clotting index of 81 +/- 40. The biocompatibility of GA, GA-DETA and GA-Taurine microgels against L929 fibroblast cells also revealed 84.4, 89.1, and 67.0% cell viability, respectively, at 25.0 mu g/mL concentration, suggesting great potential in vivo biomedical applications up to this concentration. In addition, 5 and 10 mgImL minimum inhibition concentrations of protonated GA-DETA microgels (GA-DETA-HCl) were determined against E. coli and S. aureus, respectively. (C) 2016 Elsevier Ltd. All rights reserved.