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Öğe Antimicrobial open-cell polyurethane foams with quaternary ammonium salts(Wiley, 2018) Demirci, Fatma; Yıldırım, Kenan; Koçer, Hasan BasriAn hydroxyl-terminated quaternary ammonium salt polymer (QAP) was added to a foam formulation in various amounts between 1 and 5 wt %. The structures of the produced foams and their QAP content were characterized by Fourier transform infrared and EDXRF analyses. A linear polymer of QAP with a diisocyanate was also synthesized to support our investigations. The morphological changes such as the cell size and the cell structure of the produced foams were observed with scanning electron microscopy. Thermogravimetric analysis and dynamic mechanical analysis analyses were applied to examine the thermal and thermomechanical properties of the produced foams. Relatively low amount of QAP-added foams showed very similar structural and thermomechanical properties to the unmodified foams. In addition, while the unmodified foams did not show any antimicrobial activity, the QAP-added foams provided significant inactivation against Staphylococcus aureus, yeast and mold at concentrations of about 10(2) and 10(3) CFU within 5 h of contact time. The results showed that the addition of minute amount of QAP can significantly improve the biocidal performance of the produced foams without deteriorating their structure. (C) 2017 Wiley Periodicals, Inc.Öğe Curcumin-Loaded Akermanite/Chitosan/Carboxymethylcellulose Patches for Skin Wound Healing: Fabrication, Characterization, and In Vitro Cytocompatibility(Wiley-V C H Verlag Gmbh, 2025) Mutlu, Busra; Demirci, Fatma; Ercelik, Melis; Tekin, Cagla; Tunca, Berrin; Terzioglu, Pinar; Duman, SeymaIn this study, bioactive and biocompatible transdermal patches were fabricated through the lyophilization of a chitosan/carboxymethylcellulose/akermanite composite matrix. The influence of curcumin incorporation at 0.5%, 1%, and 2% on the physicochemical, morphological, and biological properties of the patches was systematically investigated. Scanning electron microscopy revealed an interconnected porous structure with pore sizes ranging from 29 to 57 mu m, facilitating cell infiltration and nutrient transport. Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy confirmed the successful integration of akermanite and curcumin, along with characteristic interactions within the polymeric network. In vitro release studies demonstrated a biphasic profile consisting of an initial burst followed by a sustained release phase, with the CCMAKCur0.5 sample achieving the highest cumulative release (94.28%). Antioxidant performance, evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method, ranged from 21.55% (CCM) to 38.96% (CCMAKCur0.5), while higher curcumin concentrations reduced activity due to increased matrix densification. Simulated body fluid immersion confirmed apatite formation, particularly in CCMAKCur0.5 and CCMAKCur2, indicating enhanced bioactivity. Cytocompatibility studies with HUVECs showed no toxic effects, and scratch assays demonstrated that CCMAKCur0.5 most effectively promoted wound closure. Overall, the findings indicate that curcumin- and akermanite-loaded lyophilized patches represent promising candidates for transdermal therapeutic applications.Öğe Development of Curcumin-Loaded TiO2-Reinforced Chitosan Monofilaments for Biocompatible Surgical Sutures(Mdpi, 2025) Demirci, FatmaSutures provide mechanical support for wound closure after various traumas and surgical operations. Absorbable sutures are increasingly favored as they eliminate the need for secondary procedures and minimize additional damage to the wound site. In this study, chitosan sutures were produced using the dry jet-wet spinning method, achieving number 7-0 sutures (approximately 76 mu m diameter) with a homogeneous surface. FTIR analysis demonstrated molecular interactions between chitosan and TiO2 or curcumin, confirming successful incorporation. The addition of 3% TiO2 increased the tensile strength of chitosan sutures by 12.32%, reaching 189.41 MPa. Morphological analysis revealed smooth surfaces free of pores and bubbles, confirming the production of high-quality sutures. Radical scavenging activity analysis showed that curcumin-loaded sutures exhibited 43% scavenging ability after 125 h, which was significantly higher compared to pure chitosan sutures. In vitro antibacterial tests demonstrated that curcumin-loaded sutures provided 98.87% bacterial inactivation against S. aureus within 24 h. Additionally, curcumin release analysis showed a cumulative release of 77% over 25 h. The bioactivity of the sutures was verified by hydroxyapatite layer formation after incubation in simulated body fluid, supporting their potential for tissue regeneration. These findings demonstrate that TiO2 reinforcement and curcumin loading significantly enhance the functional properties of chitosan sutures, making them strong candidates for biocompatible and absorbable surgical applications.Öğe Durability of polymer composite materials for high-temperature applications(Elsevier, 2024) Parın, Fatma Nur; Demirci, Fatma“Advanced polymer composites” or “high-performance polymer composites” mainly depend on fiber, micro/nanoparticles, powder reinforcements, thermoplastic, and thermoset-based matrix components. These composites allow the development of secured, long-range airplanes, and highly light machine components in wide-range automotive and railway, aerospace, geopolymer, membrane, and energy applications. Polymer composites provide a significant contribution to our society's long-term growth. They are increasingly the material of choice whenever technological progress leads to demand for combining the characteristics that no single material can offer. The manufacturer of a composite can achieve qualities that neither material exhibits on its own by distributing fibers or particles of one component in a matrix or binder of another. This chapter explains the main and most commonly used types of high-performance polymer matrices and some of the fiber reinforcements with thermal resistance, as well as an overview of their applications in detail. Moreover, it indicates which application is potentially more dominant, as well. Finally, current troubles, future challenges, and some changing requirements are underlined and discussed. © 2024 Elsevier Ltd. All rights reserved.Öğe Electrospun PVDF Membranes Incorporated with Functionalized Carbon-based Material for Removal of Cationic Dyes(2023) Demirci, Fatma; Özsel, BurcakIn this study, polyvinylidene fluoride (PVDF) polymeric membranes with addition of functionalized carbon-based material (CBM) were fabricated by using electrospinning technique for the removal of cationic dyes from wastewater. CBM was prepared through a two-step carbonization process from cotton linter as an agricultural waste biomass. The characterization of CBM was performed by using Brunauer–Emmett–Teller (BET) surface analysis, fourier transform infrared spectrometry (FTIR) and elemental analysis. The morphologies of electrospun membranes were observed by scanning electron microscope (SEM) which clearly revealed that nanofibers with a smooth surface were produced by incorporation of CBM. According to the results obtained from FTIR and differential scanning calorimetry (DSC), crystallization behavior of PVDF membranes was promoted by increasing the percentage of CBM in the membrane. PVDF membrane prepared with the addition of 3 wt % CBM exhibited the highest water flux performance with a dye rejection of 74.6 % in comparison with the pure PVDF one.Öğe In Vitro Behavior of Boron-Doped Baghdadite/Poly(vinylidene fluoride) Membrane Scaffolds Produced via Non-Solvent Induced Phase Separation(Wiley-V C H Verlag Gmbh, 2025) Mutlu, Busra; Demirci, Fatma; Erginer, Merve; Duman, SeymaThis study explores the potential of boron-doped baghdadite (BAG) powders incorporated into poly(vinylidene fluoride) (PVDF)-based membrane scaffolds for bone tissue engineering applications. The aim is to enhance the scaffolds' microstructure, surface wettability, thermal behavior, mechanical properties, and biological performance. Composite scaffolds are fabricated by integrating the powders into the PVDF matrix, yielding scaffolds with enhanced material characteristics and functionality. The incorporation of the powders significantly enhances the hydrophilicity of the scaffolds, as evidenced by a notable reduction in contact angle measurements. Mechanical analyses demonstrate that the addition of boron-doped BAG powders reduces the tensile strength and elongation at the break of PVDF scaffolds, attribute to increased pore size, reduced crystallinity, and structural heterogeneity, though the values remain within the range of human cancellous bone. Furthermore, in vitro bioactivity studies reveal the superior apatite-forming ability of the composite scaffolds, indicating their enhanced potential for biomineralization. The results of the cellular adhesion assays indicate an enhanced affinity and proliferation of cells on the membrane scaffolds, which is indicative of improved biocompatibility. In conclusion, the developed PVDF-based membrane scaffolds, reinforce with BAG powders, show promise as effective alternatives to traditional bone graft materials, offering scalable and versatile solutions for regenerative medicine.Öğe Influence of boron incorporated biphasic calcium phosphate on mechanical, thermal, and biological properties of poly(vinylidene fluoride) membrane scaffold(Wiley, 2024) Mutlu, Buesra; Demirci, Fatma; Duman, SeymaIn this paper, boron (B)-doped biphasic calcium phosphate (BCP)/poly(vinylidene fluoride) (PVDF) membrane scaffolds were developed by the combination of non-solvent induced phase separation and lyophilization processes. In addition, the effects of the synthesized B-incorporated BCP powders on the properties of the fabricated scaffolds were investigated. The physicochemical and morphological properties of the scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The physical properties were evaluated by surface wettability and swelling measurements, whereas the mechanical properties were investigated by tensile strength measurements. The thermal behavior was determined by differential scanning calorimetry, the beta-crystallization ratio was calculated by FTIR, and the beta-phase structure was characterized by X-ray diffraction. The bioactivity was evaluated in the simulated body fluid, and the cytotoxicity of the scaffolds was also investigated by performing in vitro cell culture experiments. The results showed that the incorporation of B into the PVDF matrix improved the hydrophilicity while reducing the degree of swelling of the scaffolds. Tensile strength was slightly reduced by the powder content, but yet the strength of all scaffolds was mechanically compatible with native bone. Increasing the B content up to 0.5 and 1 wt.% was improved the thermal properties, the beta-crystalline phase fraction, and thus the piezoelectricity. Furthermore, B-doped BCP/PVDF-based scaffolds significantly promoted bioactivity, cell viability, and proliferation without cytotoxicity, compared to the PVDF scaffold, depending on the B content. In conclusion, our results indicate that the PVDF-based composites in the form of membrane scaffolds that support bone growth have the potential to be highly sought-after candidates in the field of biomedical applications.Öğe Investigating the impact of coagulation bath temperature on the properties of biphasic calcium phosphate/poly(vinylidene fluoride)-based membrane scaffold via immersion precipitation(Wiley, 2025) Mutlu, Buesra; Demirci, Fatma; Duman, SeymaIn this study, composite membrane scaffolds comprising poly(vinylidene fluoride) (PVDF) and boron-containing biphasic calcium phosphate (BCP) are developed using a non-solvent-induced phase separation technique at coagulation bath temperatures of -5, 0, 10, and 20 degrees C. The morphology, pore size and tensile strength of the scaffolds are primarily influenced by the bath temperature. Moreover, raising the bath temperature enhances the thermal properties and beta-crystalline phase fraction. Results demonstrate that changes in the temperature increase the surface hydrophilicity and reduce the degree of swelling. According to the in vitro bioactivity analysis, apatite growth is affected by the interactive relation between the surface of the samples and the simulated body fluid (SBF) medium, in addition to the superior bioactivity of the scaffolds. In vitro cytotoxicity assay results confirm the extensive spreading of L-929 cells on the sample surfaces, indicating the high biocompatibility of the scaffolds. Based on these favorable properties, the novel composite membranes produced, particularly at 20 degrees C coagulation bath temperature, may contribute to applications in bone tissue engineering. Fabrication of the BCP/PVDF-based membrane scaffold via immersion precipitation. imageÖğe OLIVE LEAF EXTRACT INCORPORATED CHITOSAN FILMS FOR ACTIVE FOOD PACKAGING(2023) Kazan, Aslihan; Demirci, FatmaPackaging materials serve as a barrier to protect the food from the environment and new approaches with improved properties, such as active packaging, is gaining more attention nowadays. In this study, chitosan films containing olive leaf extract (OLE) as an additive were prepared and characterized in terms of mechanical, structural and biological properties. The addition of OLE improved not only the tensile strength (32 MPa) and elongation (9.3%) of chitosan films but also their barrier properties such as water vapor transmission rate of 657.52 g/m2day and moisture retention capability of 90.41%. Furthermore, chitosan films gained antibacterial properties with the addition of OLE and possessed a dose and time-dependent antioxidant activity compared to their extract-free equivalents. As a consequence, the present study suggests that chitosan films incorporated with OLE are a promising alternative as an active food packaging with enhanced mechanical, barrier, antioxidant and antibacterial properties.Öğe PLA-Based 3D Porous Scaffolds with Bioceramics for Load-Bearing Bone Substitutes(Springer Nature, 2025) Ozer, Hayrunnisa; Mutlu, Büşra; Demirci, Fatma; Duman, SeymaThree-dimensional (3D) printing technology, which has been widely adopted in the field of regenerative medicine, represents a high-speed manufacturing process for biomaterials. Three-dimensional printing technology enables the precise fabrication of biomaterial scaffolds, thereby facilitating the creation of intricate structures that are tailored to the specific characteristics of the defect site. In this study, three-dimensional printing was employed to prepare composite scaffolds comprising poly (lactic acid) and monticellite. The composite scaffolds were optimized through material characterization, mechanical testing, density measurements, and in vitro swelling assessments. The results demonstrated that the Poly (lactic acid)/monticellite composites proposed in this study were highly printable, exhibiting tunable mechanical strength and density in conjunction with the monticellite component. Additionally, the in vitro swelling properties were demonstrated to be superior to those of the neat poly (lactic acid) scaffold. This composite scaffolding of poly (lactic acid) and monticellite represents a promising strategy for load-bearing bone substitutes. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.Öğe Preparation of antibacterial polyvinylidene fluoride (PVDF) ultrafiltration membranes with direct addition of N-halamine polymers(Taylor & Francis Inc, 2019) Demirci, Fatma; Koçer, Hasan BasriIn this study, novel antibacterial ultrafiltration polyvinylidene fluoride (PVDF) flat sheet membranes were produced with addition of synthesized N-halamine polymers. The ternary phase diagrams of PVDF and the synthesized polymers with N-methyl-2-pyrrolidone and water systems were prepared. The water flux and BSA rejection performances of the produced membranes were assessed both with and without PVP addition, and compared with a commercial membrane. The produced membranes were characterized with FTIR, XPS, DSC, and SEM analysis. Addition of N-halamine polymers to the membrane structure significantly improved the biocidal performance of the produced membranes against Staphylococcus aureus and Escherichia coli (10(5) CFU).Öğe Preparation of breathable polyurethane membranes with quaternary ammonium salt diols providing durable antibacterial property(Wiley, 2019) Aydın, Ahmet; Demirci, Fatma; Orhan, Mehmet; Koçer, Hasan BasriAim of this study was to produce hydrophilic breathable polyurethane membranes providing antibacterial property permanently by incorporation of a quaternary ammonium salt diol (QAS). The study was carried out by synthesis of nine different polyurethanes by solution polymerization through variations of their QAS and isocyanate contents. Fully amorphous membranes at a thickness of 30m were produced from the synthesized polymers and their thermal and morphological characteristics were determined. The effect of morphological structures on the membrane water vapor transmission rates (WVTR) and antibacterial properties were correlated. The WVTR increased with the increased temperature in all membranes over 10-40 degrees C, all produced membranes showed water resistance up to a pressure of 2100 cmH2O and WVTR values above 60g/m(2) h at 30 degrees C. The WVTR increased by increasing amount of QAS including cationic groups and decreased by increasing isocyanate amount reducing the molecular chain flexibility. In addition, while the unmodified membranes did not show any antibacterial activity, the QAS-added membranes provided significant inactivation against Staphylococcus aureus and Escherichia coli of about 104CFU within 5h of contact time. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47133.Öğe Production of ultrafiltration membranes exhibiting antibacterial properties by the incorporation of novel N-halamine copolymers(Wiley, 2022) Demirci, Fatma; Aydin, Ahmet; Orhan, Mehmet; Kocer, Hasan BasriAntibacterial PVDF flat sheet membranes are produced with the directly incorporation of novel synthesized N-halamine copolymers having high chlorine loading capacity and compatible with the base polymer. FTIR and H-1 NMR analysis are applied to the synthesized polymers and the presence of the polymers in the produce membrane structures are determined with FTIR and XPS analysis. To get information about phase separation behavior of the membrane solutions, ternary phase diagrams of the synthesized copolymers, PVDF, and their mixed solutions are prepared. The effect of synthesized polymers on membrane pore formation is revealed with ternary phase diagrams, water flux performance, BSA rejection performance, and SEM images of the produced membranes. Two different biocidal tests are applied to the membranes to determine the effectiveness of the membrane surfaces against biofilm formation, the speed of antibacterial efficiency and the duration of the biocidal activity of the membranes. The tests results show that only a small amount of copolymer incorporation into PVDF membranes solutions enables to production of antibacterial membranes with a long-term and rapid efficacy against S. aureus and E. coli bacteria.Öğe Supercritical carbon dioxide application using hydantoin acrylamide for biocidal functionalization of polyester(Elsevier, 2020) Orhan, Mehmet; Demirci, Fatma; Koçer, Hasan Basri; Nierstrasz, VincentBiocidal functionalization in polyester fibers is a really tough challenge because of the lack of tethering groups. This study indicated supercritical carbon dioxide application using N-halamine would be an alternative solution for obtaining antibacterial function on the polyester surface. Firstly, N-(2-methyl 1-(4 methyl-2,5-dioxo-imidazolidin-4 yl)propan-2-yl)acrylamide was synthesized and applied to the polyester in supercritical carbon dioxide medium, at 120 degrees C, 30 MPa for different processing times. The addition of N-halamine on the surface significantly brought antibacterial activity against E. coli. The chlorine loadings showed that 6-h exposure time was critical to obtain sufficient antibacterial activity. This treatment caused a reasonable and tolerable loss in color and mechanical properties. But, the durability to abrasion, stability, and rechargeability of oxidative chlorine, and the durability of N-halamine on the surface were remarkably good. Conclusively, it can be available to work on polyester surfaces with resource-efficient and eco-friendly supercritical carbon dioxide technique for getting more functionalization and modification. (C) 2020 Elsevier B.V. All rights reserved.Öğe Synthesis of antibacterial polymers reducing biofilm formation and their application on hollow fiber membranes(Bursa Teknik Üniversitesi, 2018) Demirci, Fatma; Koçer, Hasan BasriKlasik su arıtma sistemleri sıkılaşan standartları sağlamakta yetersiz kalmaktadırlar. Bu sebeple, ileri arıtma proseslerine olan talep gün geçtikçe artmaktadır. Membran prosesleri en çok tercih edilen ileri arıtma prosesleridir. Bu prosesler içerisinde ultrafiltrasyon (UF) membranları yaygın kullanıma sahiptir. UF membranları çapraz-akışlı veya dik-akışlı olarak işletilebilmektedir. Dik-akışlı filtrasyon yöntemi daha az enerji kullandığı için avantajlıdır, ancak zamanla diğer yönteme göre hızlı tıkanması bu sistemin önündeki en büyük engellerdendir. Tıkanmaların en önemli sebeplerinden birisi ise su arıtımı ile filtrelenen mikroorganizmaların membran yüzeyinde oluşturduğu biyofilmlerdir. Genellikle su arıtma tesislerinde, membran yüzeyinde oluşan bu biyofilmleri uzaklaştırmak için membranlara zarar veren sodyum hipoklorit gibi kimyasallar ile periyodik ters(geri)-yıkamalar yapılmaktadır. Bu yıkamalarda ortaya çıkan halojenler bir miktar daha membran yüzeyinde tutulabilirse, yıkama sayıları azaltılabilir ve membran kullanım ömürleri uzatılabilir. Bu varsayım halojenleri depolayabilen N-halamin kimyası ile gerçekleştirilebilir. Böylece her yıkama işleminde membran yüzeyleri tekrar aktifleştirilmiş olup, farklı kimyasallar kullanılmadan antibakteriyel yüzeyler elde edilmiş olacaktır. Bu çalışmada, su uygulamalarında kullanılacak ultrafiltrasyon membranların biyobozunum dirençlerini arttırmak amacıyla, matris polimer ile ortak çözgende çözülebilen, yüksek klor depolama kapasitesine sahip, klor stabilitesi yüksek ve su ile malzemeden kolayca uzaklaşmayan polimerler sentezlenmiş ve sentezlenen polimerler membran üretiminde kullanılan polimer matrislere katılarak, düz ve içi boş lifler üretilmiştir. İçi boş lif üretimi için bir kuru-jet-yaş çekim hattı ve bir düze tasarlanmış ve üretilmiştir. Kurulan sistemde içi boş lifler başarıyla üretilmiş ve geçirgenlik testleri için modül formunda paketlenmiştir. Membranların üretiminde kullanılan polimerlerin üçlü faz diyagramları ile düz ve içi boş liflerin morfolojik ve yüzey özellikleri incelerenek sentezlenen antibakteriyel polimerlerin yapıya olan etkileri belirlenmiştir. Geçirgenlik testleri ve SEM analizleri yardımıyla membranların gözeneklilikleri hakkında bilgi edinilmiş, katkısız membrana göre membranın su akısı ve protein reddi değerlerindeki iyileşmeler ortaya konulmuştur. Ayrıca elde edilen düz membran geçirgenlik değerleri halihazırda ticari olarak kullanılan bir PVDF membran ile kıyaslanarak, elde edilen protein reddi değerlerinin ticari membrandan dahi yüksek olduğu görülmüştür. Yine benzer şekilde üretilen içi boş lifler ticari kataloglardaki akı değerlerine çok yakın su akısı değerleri göstermiştir. Son olarak üretilen membranların farklı test yöntemleriyle hızlı ve uzun süreli bir antibakteriyel etkinliğe sahip olduğu kanıtlanmıştır.
