Browsing by Author "Özkan A.N."

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    Novel ferrocenyl pyrazoles inhibit breast cancer cell viability via induction of apoptosis and inhibition of PI3K/Akt and ERK1/2 signaling
    (Elsevier Ireland Ltd, 2017) Atmaca H.; Özkan A.N.; Zora M.
    Despite the advances in early detection and targeted therapies, chemotherapy is still of vital importance in breast cancer treatment. However, development of drug resistance and serious side effects limits their usage. Thus, there is an urgent need for safer and more effective agents against breast cancer. We have previously described the synthesis of a number of pyrazole derivatives, and in the current study, we have investigated the effects of two different ferrocenyl pyrazole (FP) derivates, 5-ferrocenyl-1-phenyl-1H-pyrazole (FP-Ph) and 5-ferrocenyl-1H-pyrazole (FP-H), on breast cancer cells. First, we investigated the effects of both FPs on cell viability and induction of cell death in breast cancer cells and benign MCF-10A cells by XTT and DNA fragmentation assays, respectively. Morphological changes in human breast cancer cells after FPs treatment were detected by both phase contrast microscope and atomic force microscopy (AFM). Then, we tested whether FPs exert their cytotoxic effect through inhibiting PI3K/Akt and/or ERK1/2 signaling pathways by using specific inhibitors. Both FPs induced cytotoxicity in a time and concentration-dependent manner in breast cancer cells; however, MCF-10A benign breast epithelial cells were much less susceptible to the cytotoxic effect of both FPs. FPs inhibited both PI3K/Akt and ERK 1/2 signaling pathways in breast cancer cells. The ultra structure images of MCF-7 cells by AFM showed that the cell surface was smooth in untreated cells, but it was rough with protrusions in treated cells. Both FPs induced apoptotic cell death in MDA-MB-231 cells; however, necrotic cell death was induced in caspase-3 lack MCF-7 cells, which implies that the synthesized FPs may induce apoptosis through caspase-3 dependent mechanism. In summary, these results suggest that FPs might be promising agents for the breast cancer therapy. © 2016 Elsevier Ireland Ltd
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    Preparation, characterization and thermal properties of polypropylene/polyethylene/zinc borate composites: investigation of thermal degradation kinetics
    (Springer Science and Business Media B.V., 2023) Saltan F.; Şentürk S.; Al A.M.; Özkan A.N.; Şirin K.
    In this study, polypropylene/polyethylene/zincborate composites (PP/HDPE/Zinc Borate) were prepared using high-density polyethylene, isotactic polypropylene, and a certain percentage of zinc borate. The composites were characterized using by X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDX), Fourier Transform Infrared (FT-IR) spectroscopy analyses. The thermal behavior of the materials was investigated using thermogravimetric analysis (TG), Differential Thermal Analysis (DTA), and Differential Thermogravimetry (DTG). The thermal degradation kinetics of the PP/HDPE/Zinc Borate15% composite was investigated. The apparent activation energies (Ea) were obtained following the differential and integral methods of Kissenger and Flynn-Wall-Ozawa (FWO). Using Kissinger's and Flynn–Wall–Ozawa methods to define thermal degradation of PP/HDPE/Zinc Borate%15, their activation energies were 233.3 kJ/mol and 189.3 kJ/mol, respectively. The mechanism of the studied conversion range was found to be the R3 deceleration model using the Coats–Redfern. The viscosity and shear stress of PP/HDPE/Zinc Borate15% were determined using a cone-plate type rheometer. PP/HDPE/Zinc Borate15% composite shows plastic-type fluidity, according to rheological analysis. © 2023, The Polymer Society, Taipei.