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Öğe Beyond Conventional: Antibacterial, Antioxidant, and Photocatalytic Properties of Nanofibers Featuring Metal-Oxide-Modified Boron Nitride Nanoparticles(Amer Chemical Soc, 2024) Horzum, Nesrin; Doğan, Deniz; Karaduman, Fatma Rabia; Metin, Ayşegül ÜlküCuO-, ZrO2-, and ZnO-immobilized functional boron nitride (fBN) nanoparticles were synthesized by an environmentally friendly approach using a Stevia rebaudiana extract. Metal-oxide-immobilized fBN nanoparticles (fBN/MO)-incorporated (1 wt %) polyvinyl alcohol/poly(acrylic acid) composite nanofibers were fabricated by electrospinning, and their antibacterial, antioxidant, and photocatalytic properties were investigated. fBN/CuO and fBN/ZnO nanoparticles were distributed randomly, showcasing nonuniform geometries besides polygonal-shaped fBN/ZrO2 nanoparticles. fBN/MO nanoparticles exhibited a uniform dispersion along the composite nanofibers, with diameters between 115 and 160 nm. The incorporation of fBN/MO nanoparticles into the composite nanofibers (0.074-0.753 W/mK) resulted in an improvement in both thermal stability and conductivity when compared with PVA/PAA nanofibers (0.063 W/mK). fBN/MO-modified composite nanofibers exhibited an antibacterial efficacy exceeding 99% against Streptococcus mutans, Acinetobacter baumannii, Escherichia coli, and Staphylococcus aureus, augmenting their antioxidant properties. The modified composite nanofibers, particularly those incorporating fBN/ZrO2 nanoparticles, exhibited effective photocatalytic remediation against methylene blue (MB) with the highest activity, attributed to their favorable morphological and optoelectronic properties, resulting in a remarkably more than 20-fold improvement. Enhanced stability for repeated treatment of MB for a minimum of three cycles was achieved. The multifunctional nature of nanofibers unveils synergistic antibacterial, antioxidant, and photodegradation effects, positioning them as promising for biomaterials and water disinfection.Öğe Biyouyumlu Malzemelerin Üretimi için 4D Eklemeli İmalat Cihazı Tasarımı ve Üretimi(Kırıkkale Üniversitesi, 2023) Kartal, Yunus; Doğan, Deniz; Daş, Memik Taylan; Metin, Ayşegül ÜlküBu çalışmanın amacı biyouyumlu malzemelerin üretimi için alışılagelmiş kartezyen eksenlerinin haricinde tablada bulunan ve ekseni etrafında dönen dördüncü eksene sahip dört boyutlu (4D) eklemeli imalat cihazı tasarımı ve üretimidir. Bu kapsamda çeşitli mekanik ve elektronik aksesuar veya bileşenlerin teorik ve teknik detayları verilmektedir. Çalışma kapsamındaki dört boyutlu yazıcı üretilen malzemelerin özelliklerinin atmosfer koşullarından etkilenmesini engellemek amacıyla izole bir ortamda çalışmaktadır. Tasarımı ve üretimi gerçekleştirilen cihazda ultraviyole ışın altında poli(2-hidroksietil metakrilat) üretilmiş ve mekanik özellikleri incelenmiştir.Öğe Metal oksitli ve metal oksitsiz ortamlarda polianilin sentezi, karakterizasyonu ve fotokatalitik etkisinin incelenmesi(Kırıkkale Üniversitesi, 2015) Doğan, Deniz; Can, MuzafferTez çalışmasında, iletken polimer olan polianilin metal oksitli ve metal oksitsiz olmak üzere iki farklı ortamlarda sentezlenmiştir. Elde edilen polimerler FTIR, SEM, EDAX, XRD ve iletkenlik ölçümleri ile karakterize edilmiştir. İletkenlik ölçümleri four probe yöntemi ile yapılmıştır. Sentezlenen polimerler ve polimer sentezinde kullanılan metal oksitler kullanılarak kirletici bir boya olan metilen mavisinin bozunması üzerinde fotokatalitik aktiviteleri incelenmiştir. Polimerlerin ve metal oksitlerin fotokatalitik etkilerine, kirletici miktarı, zaman, karanlık ortam ve UV ışık etkisi ayrı ayrı araştırılmıştır. Elde edilen deneysel sonuçlar, kirletici miktarının, zamanın ve UV ışığının fotokatalitik bozunma üzerine etki ettiğini göstermiştir. Ayrıca fotokatalitik etki üzerine polimer ve yarı iletken özellik gösteren yarı iletken metal oksitlerin band gap aralıklarının da etki ettiği belirlenmiştir.Öğe Novel magnetic gel beads based on ionically crosslinked sodium alginate and polyanetholesulfonic acid: Synthesis and application for adsorption of cationic dyes(ELSEVIER SCIENCE SA, 2020) Metin, Ayşegül Ülkü; Doğan, Deniz; Can, MuzafferThis study offers novel magnetic gel beads as an adsorbent containing bifunctional groups for cationic dye removal. The bifunctional composite gel beads were prepared from polyanetholesulfonic acid, alginate and magnetic zeolite (m-ALG/PESA), and characterized by FESEM-EDS, XRD, VSM, and TGA-FTIR. The adsorption capability of m-ALG/PESA beads was described using methylene blue (MB) and malachite green (MG). The maximum adsorption capacities of MB and MG onto m-ALG/PESA gel beads were 400 mg/g and 164 mg/g, respectively. Regeneration and reusability studies showed that both dyes were successfully desorbed from mALG/PESA gel beads with removal percentages approximately 90 in the first cycle and magnetic gel beads maintained their shapes after 10 times adsorption/desorption cycles in highly acidic conditions. It was also observed that MG was degraded during the desorption process. Therefore, the magnetic gel beads can be considered as a regenerable adsorbent making to the adsorption process is cost-effective and it is also biodegradable and environment-friendly material when used in pilot-scale applications.Öğe One-pot green approach for rapid and effective anionic dye remediation: encapsulation within alginate nanocapsules(Wiley, 2024) Alver, Erol; Doğan, Deniz; Mert Balaban, Hümeyra; Metin, Ayşegül ÜlküBACKGROUNDThe encapsulation technique was applied to efficiently eliminate Congo red (CR) from aqueous solutions. During the ionotropic gelation between calcium (Ca2+) ions and alginate (AL), CR was effectively entrapped within the AL nanocapsules in a one-step process. Suitable conditions for efficient CR removal via encapsulation were revealed by the systematic optimization of parameters including pH, time and stirring speed, etc.RESULTSAccording to the experimental observations, the stirring rate and temperature were found to have an insignificant effect on the encapsulation of CR molecules. When the pH value of the medium was 3, the highest level of encapsulation efficiency was achieved in a period of 15 min. At a preliminary CR concentration of 2000 mg L-1 and pH 3, the encapsulation efficiency was calculated at approximate to 98.9%, with an encapsulation capacity of 2800 mg dye g-1 AL. The zeta potential values of AL and CR/AL nanocapsules were determined to be +7.05 eV and -14.9 eV, respectively, and the results showed that the particles tended to agglomerate. TEM micrographs also showed that the nanocapsules were nanosized and agglomerated. Soil and UV degradation studies showed that the dye-entrapped nanocapsules degraded remarkably. These results highlighted the great potential of encapsulation for dye removal in economical and practical applications.CONCLUSIONEncapsulation was confirmed to be an economical and practical technique for effectively eliminating CR from aqueous solutions. Under UV light irradiation, the dye molecules entrapped within alginate nanocapsules displayed photodegradation. (c) 2024 Society of Chemical Industry (SCI).Öğe Physicochemical and biological assessment of boron nitride nanosheets-reinforced poly(2-hydroxyethylmethacrylate) composite for biomedical applications(Elsevier, 2022) Doğan, Deniz; Metin, Ayşegül ÜlküResearch on mechanically advanced materials for biological applications involving load-bearing is in progress. Within this scope, this study is the first to propose the fabrication of bionanocomposites combining the different amounts of functionalized boron nitride nanosheets (f-BNNSs, 0-2.0 mg/mL) and poly(hydroxyethyl methac-rylate) (pHEMA). The pristine BN was exfoliated by microwave irradiation to access BNNSs at different powers and times. The as-exfoliated BNNSs were characterized by zeta-sizer, FTIR, XRD, and TEM, which showed that the BNNSs exhibited facile and processable features in tiny sizes. Bionanocomposites were fabricated by pho-topolymerization. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of bionanocomposites were evaluated. The mechanical parameters such as Young's modulus and elongation per-centage at break showed that adding f-BNNSs up to 2.0 mg/mL significantly increased the mechanical strength of pHEMA without affecting the hydrophilicity, hemocompatibility, and cytotoxicity. Moreover, the hardness of pHEMA/f-BNNSs composites (38.56 MPa) was remarkably higher than that of pHEMA. There was no cytotoxicity recorded for fabricated bionanocomposites from the MTT assay. All nanocomposites exhibited superior anti-bacterial activities against E.coli and S.aureus compared with pHEMA. However, pHEMA/f-BNNSs composites were more effective against E.coli than S.aureus. While E.coli colonies was reduced 100% at all composites in an hour, S.aureus colonies was completely destroyed with pHEMA/1f-BNNSs and pHEMA/2f-BNNSs after 24 h in-cubation. The study's findings demonstrated that the mechanically improved pHEMA/f-BNNSs films could in-crease the application of pHEMA in biomedical fields.Öğe Resorbable membrane design: In vitro characterization of silver doped-hydroxyapatite-reinforced XG/PEI semi-IPN composite(Elsevier, 2023) Doğan, Deniz; Erdem, Ümit; Bozer, Büşra M.; Turkoz, Mustafa Burak; Yıldırım, Gürcan; Metin, Ayşegül ÜlküIn this study, the production and characterization of silver-doped hydroxyapatite (AgHA) reinforced Xanthan gum (XG) and Polyethyleneimine (PEI) reinforced semi-interpenetrating polymer network (IPN) biocomposite, known to be used as bone cover material for therapeutic purposes in bone tissue, were performed. XG/PEI IPN films containing 2AgHA nanoparticles were produced by simultaneous condensation and ionic gelation. Characteristics of 2AgHA-XG/PEI nanocomposite film were evaluated by structural, morphological (SEM, XRD, FT-IR, TGA, TM, and Raman) and biological activity analysis (degradation, MTT, genotoxicity, and antimicrobial activity) techniques. In the physicochemical characterization, it was determined that 2AgHA nanoparticles were homogeneously dispersed in the XG/PEI-IPN membrane at high concentration and the thermal and mechanical stability of the formed film were high. The nanocomposites showed high antibacterial activity against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S.aureus), and Streptococcus mutans (S.mutans). L929 exhibited good biocompatibility for fibroblast cells and was determined to support the formation of MCC cells. It was shown that a resorbable 2AgHA-XG/PEI composite material was obtained with a high degradation rate and 64% loss of mass at the end of the 7th day. Physico-chemically developed biocompatible and biodegradable XG-2AgHA/PEI nanocomposite semi-IPN films possessed an important potential for the treatment of defects in bone tissue as an easily applicable bone cover. Besides, it was noted that 2AgHA-XG/PEI biocomposite could increase cell viability, especially in dental-bone treatments for coating, filling, and occlusion.
