Browsing by Author "Celikkan H."

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    Calibration Curve Approaches for Nonlinear Data Points Obtained in Colo 320 Exosomes Determination
    (Center of Excellence in Electrochemistry, Univ. of Tehran, 2022) Sazaklioglu S.A.; Torul H.; Kabadayi H.; Vatansever H.S.; Tamer U.; Celikkan H.
    The limit of detection (LOD) is defined as the lowest quantity or concentration of a component that can be reliably distinguished from the limit of blank (LOB). LOD value is one of the most important parameters considered for many determination methods and is usually calculated on the linear correlation between signal and concentration. However, the linear correlation may not always be obtained in experimental studies. We claim that data with low linear correlation have meaning, and we present such a study because analytical studies based on these data are not easily understood in the literature. In this manuscript, we suggest that a calibration curve can be obtained from nonlinear data points and the LOD value can be calculated. We tested this approach for the determination of exosomes and supported it with mathematical calculations. We produced a label-free sensor using anti-CD63 on the gold electrode for selective and reliable impedimetric detection of the exosomes obtained from Colo 320 cell lines in data points that are high concentrations and out of linearity. We characterized in detail what each calculation means. This sensor with a LOD value of 3.90×1011 exosome particles µL-1 and with a cubic polynomial model for the calibration curve was considered sensitive and reliable, especially for high vesicle content of samples such as cell culture medium. © 2022 by CEE (Center of Excellence in Electrochemistry).
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    Boron-Doped Carbon Nanodots as a Theranostic Agent for Colon Cancer Stem Cells
    (American Chemical Society, 2023) Ozkasapoglu S.; Caglayan M.G.; Akkurt F.; Ensarioğlu H.K.; Vatansever H.S.; Celikkan H.
    Carbon nanodots have drawn a great deal of attention due to their green and expedient opportunities in biological and chemical sciences. Their high fluorescence capabilities and low toxicity for living cells and tissues make them excellent imaging agents. In addition, they have a fluorimetric response against inorganic and organic species. Boron-doped carbon nanodots (B-CDs) with high fluorescence yield were produced from phenylboronic acid and glutamine as boron and carbon sources, respectively, by a hydrothermal method. First, the effects of the temperature on their fluorescence yield and the structural characteristics of B-CDs were investigated. Second, their cytotoxicity and cell death and proliferation behaviors were examined. The cytotoxicity was evaluated by the MTT assay. The cellular properties were evaluated with the distribution of caspase 3, Ki67, lamin B1, P16, and cytochrome c after the indirect immunoperoxidase technique. After the MTT assay, 1:1 dilution of all applicants for 24 h was used in the study. After immunohistochemical analyses, the application of B-CDs synthesized at 230 °C did not change control cell (Vero) proliferation, and also apoptosis was not triggered. Colo 320 CD133+ and CD133- cell-triggered apoptosis and cellular senescence were found to be synthesis temperature dependent. In addition, Colo 320 CD133- cells were affected relatively more than CD133+ cells from B-CDs. While B-CDs did not affect the control cells, the colon cancer stem cells (Colo 320 CD133+) were affected in a time-dependent manner. Therefore, the use of the synthesized B-CD product may be an alternative method for controlling or eliminating cancer stem cells in the tumor tissue. © 2023 The Authors. Published by American Chemical Society