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    Öğe
    CRISPR-Cas İmmün Sisteminin Biyolojisi, Mekanizması ve Kullanım Alanları
    (Kırıkkale Üniversitesi, 2016) Gün Gök, Zehra; Çağdaş Tunalı, Beste
    Hedeflenmiş nükleazlar genomdüzenlenmesinde yaygın olarak kullanılmaktadır. Kısa süre önce, düzenliaralıklarla bölünmüş palindromik tekrar kümeleri (CRISPRs)-ilişkili Cas9nükleazları genom düzenleme çalışmalarında ilk defa kullanılmış ve o zamandanberi bu alanda devrim yaratmıştır. CRISPR-Cas9 genom düzenleme aracının bubüyük başarısının ardında Cas9’u istenilen DNA lokusuna hedefleyen kılavuzRNA’nın tasarımının basitliği ve CRISPR-Cas9 aracılı DNA kırılmalarının yükseközgüllük ve verimlilikte olması yatmaktadır. Yakın zamanda yapılan bazıçalışmalarda, in vivo hayvanmodellerinde ve ex vivo somatik veuyarılmış pluripotent kök hücrelerinde hastalığa neden olan allellerindüzenlenmesinde CRISPR-Cas9 sistemi başarıyla kullanılarak terapötik genomdüzenlenmesinin klinik uygulamaları için umutları arttırmıştır. Bu derleme ilebu sistemlerden en çok kullanılan CRISPR-Cas9 Tip II sisteminin diğersistemlere göre avantaj ve dezavantajları belirtilmiş ve bu sistemler ileyapılan uygulamalara değinilmiştir. Ayrıca bu derlemede, çeşitli araştırma yada translasyonel uygulamalarda kullanılan ve olağanüstü bir mikrobiyal savunmasisteminden türetilen CRISPR-Cas9’un gelişiminden ve uygulamalarındakizorluklarından bahsedilmiştir.
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    Öğe
    Effects of functional poly(ethylene terephthalate) nanofibers modified with sericin-capped silver nanoparticles on histopathological changes in parenchymal organs and oxidative stress in a rat burn wound model
    (Ankara Univ, 2023) Şahin, Yaşar; Gün Gök, Zehra; Alçığır, Mehmet Eray; Çınar, Miyas
    In this study, it was aimed to investigate the effect of a poly(ethylene terephthalate)-g-poly(hydroxyethyl methacrylate) (PET-g-HEMA) nanofiber wound dressing modified with sericin-coated silver nanoparticles (S-AgNPs) on internal organs, oxidative stress, and biochemical parameters. To establish a burn model, the backs of anesthetized rats were shaved and then third-degree burns were created with a round-bottomed stainless steel rod 2 cm in diameter kept in 100 degrees C water for 20 seconds. The wounds of the negative control group (G1) were covered with standard bandages; the wounds of the positive control group (G2) were covered with silvercel, used as burn wound material; and the wounds of the experimental group (G3) were covered with PET-based dressing material. Histopathological changes in organs (liver, kidneys, heart, pancreas, lungs), total oxidant status (TOS), total antioxidant status (TAS), nitric oxide (NO), and biochemical parameters (serum aspartate aminotransferase [AST], alanine aminotransferase [ALT], gamma glutamyl transpeptidase [GGT], creatine kinase, lactate dehydrogenase [LDH], total protein, albumin, globulin, urea) were examined. Compared with the G1 group, plasma AST, ALT, and GGT levels were found to be significantly decreased in G2 and G3 (P<0.001). Plasma TAS was found to be significantly increased in G2 and G3 compared to G1 (P<0.05). Compared to the G1 group, degenerative and necrotic changes in the liver, kidneys, and pancreas were found to be significantly reduced in G2 and G3 (P<0.05). In conclusion, this work demonstrates that the synthesized PET-based wound dressing material has the capacity to be used commercially.
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    Öğe
    Synthesis and characterization of polyvinyl alcohol–silk sericin nanofibers containing gelatin-capped silver nanoparticles for antibacterial applications
    (Springer Science and Business Media Deutschland GmbH, 2022) Gün Gök, Zehra
    In this study, nanofiber surfaces were produced from a mixture of polyvinyl alcohol and silk sericin protein (PVA:SS) containing gelatin-coated silver nanoparticles (G-AgNPs) by electrospinning. For preparation of G-AgNPs, gelatin solution (1%, w/v) was mixed with 5 mM of AgNO3 solution and the mixture was heated and stirred for 2 h. AgNPs production has been observed with the brown color change that occurred in the solution. The absorbance of G-AgNPs was measured with a UV–Vis spectroscopy in the 300–700 nm range, and it was proved that AgNPs were formed with the surface plasmon resonance peak observed at 420 nm. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray analysis (EDS) analyses revealed that G-AgNPs were in spherical form and contained C, H, N, Ag elements in their structures, respectively. Antibacterial activity of the synthesized of G-AgNPs was shown with agar well diffusion test against to Escherichia coli and Staphylococcus aureus bacteria. In the second stage of the study, PVA:SS solutions were turned into nanofibers by electrospinning at certain conditions. G-AgNPs solutions were added in 3 different ratios of 10, 20 and 30% by volume to PVA:SS solutions, and these mixtures were turned into nanofibers with the same conditions. It has been shown by Fourier transform infrared spectroscopy (FTIR) analyses that the nanofiber surfaces obtained were composed of PVA:SS blend. The morphologies of nanofiber surfaces were investigated by FESEM analysis, and compared to PVA nanofibers collected alone, the fiber diameters of the groups containing PVA, sericin and G-AgNPs were found to be much lower. The presence of silver in nanofibers containing G-AgNPs was proven by EDS and X-ray fluorescence analyses. The thermal properties of nanofiber surfaces were investigated by thermogravimetric analysis, and it was observed that the thermal stability of nanofiber surfaces increased with the addition of sericin and G-AgNPs to PVA. Then, liquid medium tests were performed for finding the antibacterial activity of nanofiber surfaces containing various proportions of G-AgNPs on E. coli and S. aureus bacteria, and it was observed that nanofiber surfaces containing certain amounts of G-AgNPs inhibited the growth of both bacteria. It is thought that the functional and antibacterial surfaces obtained in the study will have the capacity to be used in many different areas such as wound dressing material. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Öğe
    Synthesis, characterization and in vitro release analysis of pluronic F127 copolymer micelles containing quercetin as a hydrophobic drug
    (Springer Science and Business Media Deutschland GmbH, 2024) İspir, Elif; İnal, Murat; Gün Gök, Zehra; Yiğitoğlu, Mustafa
    The object of the present study is to develop a new controlled drug release system by loading quercetin into pluronic F127 micelles. For the experimental studies, first of all, the critical micelle concentration (CMC) of the pluronic F127 copolymer was found as 4.5% g/mL at 25 °C, since the micelle-forming surfactants formed micelles at concentrations equal to or higher than the CMC. Afterward, with thin-film hydration method, three micelle groups with different polymer/quercetin ratios were formed. In this procedure, pluronic F127 polymer dissolved in ethanol at 30–40 °C and different amount of quercetin was added to the polymer solution. The polymer-quercetin solutions were evaporated in the evaporator at 40 °C for 2 h to obtain a film. The resulting film was hydrated by adding of ultrapure water and the micelle suspensions were obtained after filtration. According to Malvern Zetasizer measurement and transmission electron microscope (TEM) analysis, quercetin loaded micelles were determined to have particle sizes between 40 and 50 nm. It was determined by fourier-transform infrared spectroscopy (FTIR) analysis that quercetin was physically found into pluronic F127 micelles without any chemical reaction. It was determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyzes that quercetin was present in amorphous form as a solid solution instead of in crystalline form in the micelles. Thermogravimetric analysis (TGA) analysis showed that loading quercetin into the micelles did not affect the thermal stability of the PF127 copolymer. The drug loading amounts for micelles were found between 1.95% and 3.3% (mg/mg) for different micelles groups and there was not much difference in the percentage of encapsulation efficiency values thought to the groups. In vitro release profiles of quercetin-loaded micelles were investigated in pH 7.4 phosphate buffer solution and at 37 °C. When the release results were examined in general, it was seen that the release rates of all formulations were almost the same after 168 h. The kinetic parameters of the release results of the micelles in different formulations were calculated according to the Peppas equation and it was determined that the quercetin release in each micelle formulation did not comply with Fick’s law, according to the calculated n parameter. Quercetin-loaded polymeric micelles obtained in this study offer advantages due to their easy synthesis methods and slow release profiles and they can used to successfully encapsulation of hydrophobic active ingredients like quercetin. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.