Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - Scopus: 1Oxidizer Gases Effects on the Diameter-Controlled Synthesis of Carbon Nanotubes(MIM Research Group, 2021) İnce Yardımcı, Atike; Öğütlü, Ahmet Sabri; Öğütlü, DenizIn this study, the influence of the oxidizers on the synthesis of carbon nanotubes by C2H4 decomposition over Fe catalyst has been investigated. CO2, O2, and H2O have been used as oxidizers, and to control catalyst particle formation and their sizes in the pretreatment stage. The same oxidizers have also been used in the growth stage to maintain the catalyst particle size, remove amorphous carbon formation to keep catalyst particle active. The results of scanning electron microscopy indicated that the average diameters of nanotubes decreased from 13.4±1.2 nm to 6.2±0.5 nm and extremely dense nanotubes were obtained when we added a small amount of CO2. Adding O2 extremely decreased the areal carbon nanotube density while widens the diameter distribution. H2O addition resulted in larger average diameters and made the growth strongly pretreatment dependent. Within the parameters tried for catalyst pretreatment and CNT growth processes, CO2 seemed the best choice for a weak oxidizing assistant. The strong dependency of the average diameter on pretreatment conditions indicated that pretreatment is a very important step in deciding the final diameters and their distribution.Article Citation - WoS: 13Citation - Scopus: 14Detection of Crispr-Cas9 Mutations Using a Carbon Nanotube-Modified Electrochemical Genosensor(MDPI, 2021) Kıvrak, Ezgi; Pauzaite, Tekle; Copeland, Nikki A.; Hardy, John G.; Kara, Pınar; Fırlak, Melike; İnce Yardımcı, Atike; Yılmaz, Selahattin; Palaz, FahreddinThe CRISPR-Cas9 system has facilitated the genetic modification of various model organisms and cell lines. The outcomes of any CRISPR-Cas9 assay should be investigated to ensure/improve the precision of genome engineering. In this study, carbon nanotube-modified disposable pencil graphite electrodes (CNT/PGEs) were used to develop a label-free electrochemical nanogenosensor for the detection of point mutations generated in the genome by using the CRISPR-Cas9 system. Carbodiimide chemistry was used to immobilize the 5 '-aminohexyl-linked inosine-substituted probe on the surface of the sensor. After hybridization between the target sequence and probe at the sensor surface, guanine oxidation signals were monitored using differential pulse voltammetry (DPV). Optimization of the sensitivity of the nanogenoassay resulted in a lower detection limit of 213.7 nM. The nanogenosensor was highly specific for the detection of the precisely edited DNA sequence. This method allows for a rapid and easy investigation of the products of CRISPR-based gene editing and can be further developed to an array system for multiplex detection of different-gene editing outcomes.Article Citation - WoS: 11Citation - Scopus: 13Effect of Cnt Incorporation on Pan/Ppy Nanofibers Synthesized by Electrospinning Method(TÜBİTAK, 2020) İnce Yardımcı, Atike; Tanoğlu, Metin; Yılmaz, Selahattin; Selamet, YusufIn this study, carbon nanotubes (CNTs) added polyacrylonitrile/polypyrrole (PAN/PPy) electrospun nanofibers were produced. Average diameters of the nanofibers were measured as 268 and 153 nm for 10 and 25 wt% of PPy contents, respectively. A relatively higher strain to failure values (23.3%) were observed for the low PPy content. When as-grown CNTs (1 and 4 wt%) were added into the PAN/PPy blends, disordered nanofibers were observed to form within the microstructure. To improve the interfacial properties of CNTs/PAN/PPy composites, CNTs were functionalized with H2SO4/HNO3/HCl solution. The functionalized CNTs were well dispersed within the nanofibers and aligned along the direction of nanofibers. Therefore, beads formation on nanofibers decreased. The impedance of the nanofibers was found to decrease with the PPy content and CNT addition. These nanofibers had a great potential to be used as an electrochemical actuator or a tissue engineering scaffold.Article Citation - WoS: 25Citation - Scopus: 27Osteogenic Differentiation of Mesenchymal Stem Cells on Random and Aligned Pan/Ppy Nanofibrous Scaffolds(SAGE Publications, 2019) Selamet, Yusuf; İnce Yardımcı, Atike; Baskan, Öznur; Yılmaz, Selahattin; Meşe, Gülistan; Özçivici, EnginThe aim of this study was to develop random and aligned polyacrilonitrile (PAN)/polypyrrole (PPy) nanofibrous scaffolds by electrospinning technique for osteogenic differentiation of mesenchymal stem cells. Nanofibers were fabricated successfully as straight, smooth, and free from bead formation. The average diameter of random and aligned nanofibers was 268(+/- 49) nm and 225(+/- 72) nm, respectively. Alignment process increased the tensile strength of nanofibers 3.9-fold, while the tensile strain of nanofibers decreased by 78%. PAN/PPy nanofibers were hydrophilic with the contact angle value of about 32 degrees and alignment did not affect the contact angle value. Random and aligned PAN/PPy nanofibers were investigated as a scaffold material for osteogenic differentiation of D1 ORL UVA mouse bone marrow mesenchymal stem cells. Cells were able to attach and grow on nanofibers confirmed by cell viability results. Stem cells that were cultured with osteogenic induction were able to mineralize on electrospun nanofibers based on alizarin red and Von Kossa dye staining. For aligned PPy nanofibers, mineralization occurred in the fiber alignment direction. Consequently, PAN/PPy nanofibrous mats in both random and aligned forms would be potential candidates for bone tissue engineering.Article Citation - WoS: 18Citation - Scopus: 17Cnt Incorporated Polyacrilonitrile/Polypyrrole Nanofibers as Keratinocytes Scaffold(Trans Tech Publications, 2019) İnce Yardımcı, Atike; Aypek, Hande; Öztürk, Özgür; Yılmaz, Selahattin; Özçivici, Engin; Meşe, Gülistan; Selamet, YusufPolypyrrole (PPy) is an attractive scaffold material for tissue engineering with its non-toxic and electrically conductive properties. There has not been enough information about PPy usage in skin tissue engineering. The aim of this study is to investigate biocompatibility of polyacrilonitrile (PAN)/PPy nanofibrous scaffold for human keratinocytes. PAN/PPy bicomponent nanofibers were prepared by electrospinning, in various PPy concentrations and with carbon nanotube (CNT) incorporation. The average diameter of electrospun nanofibers decreased with increasing PPy concentration. Further, agglomerated CNTs caused beads and disordered parts on the surface of nanofibers. Biocompatibility of these PAN/PPy and PAN/PPy/CNT scaffolds were analyzed in vitro. Both scaffolds provided adhesion and proliferation of keratinocytes. Nanofiber diameter did not significantly influence the morphology of cells. However, with increasing number of cells, cells stayed among nanofibers and this affected their shape and size. In this study, we demonstrated that PAN/PPy and PAN/PPy/CNT scaffolds enabled the growth of keratinocytes, showing their biocompatibility.Article Citation - WoS: 28Citation - Scopus: 31The Effects of Catalyst Pretreatment, Growth Atmosphere and Temperature on Carbon Nanotube Synthesis Using Co-mo/Mgo Catalyst(Elsevier Ltd., 2015) İnce Yardımcı, Atike; Yılmaz, Selahattin; Selamet, YusufThe growth of high quality and high yield carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CVD) of CH4 over Co-Mo/MgO catalyst was investigated for different growth temperatures and H2 flow rates. It was observed that CNT yield decreased with the H2 flow rate, however, quality increased with increasing H2 flow rate. CNT yield increased for the temperatures 850-950 °C but dropped significantly above 950 °C. In this study, the highest yield of 1526% was obtained at the growth temperature of 950 °C. The optimum H2 flow rate was 200 sccm; this rate gave both high graphitization and high yield of product. Various CNT growth atmospheres including Ar, H2 and the mixture of both gases were also analyzed and it was observed that the highest quality CNTs were obtained for both pretreatment and growth carried out with H2. This gave a high yield of 292%. On the other hand, CNT growth carried out under Ar atmosphere gave higher CNT yield of 368%, however, the CNTs grown with Ar were more defective and had larger diameters. Prime novelty statement We demonstrate a sorbitol added catalysis synthesis method and importance of the ideal growth conditions to improve high quality single walled carbon nanotube yield up to 1500%.Article Citation - WoS: 15Citation - Scopus: 14Development of Electrically Conductive and Anisotropic Gel-Coat Systems Using Cnts(Elsevier Ltd., 2013) İnce Yardımcı, Atike; Tanoğlu, Metin; Selamet, YusufElectrical conductivity of an unsaturated thermoset polyester based gel-coat system containing 0.05 wt.% of carbon nanotubes (CNTs) was investigated. The CNTs used were synthesized by chemical vapor deposition method by methane decomposition and Raman characterization showed that they were mostly single walled and high quality. To disperse CNTs in the gel-coat resin, 3-roll milling technique was used. It was found that as the CNTs are added to gel-coat system, resistivity value decreases significantly while neat gel-coat showed a high resistivity. By the application of an AC electrical field during curing process, it was attempted to align CNTs in the gel-coat resin and an electrically anisotropic polymer was obtained. © 2012 Elsevier B.V. All rights reserved.