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    Öğe
    Graphene quantum dots: Synthesis, characterization, cell viability, genotoxicity for biomedical applications
    (Elsevier, 2019) Senel, Behiye; Demir, Neslihan; Buyukkoroglu, Gulay; Yıldız, Mustafa
    We report the synthesis and applications of a novel N-doped graphene quantum dots (GQDs) using hydrothermal reaction between citric acid and p-aminophenol. The synthesized N-doped GQDs have been characterized physico-chemically and evaluated its antioxidant, antimicrobial, DNA binding and cleavage activities. siRNA loading studies were performed and their effects on cells were evaluated. Obtained results indicate that monodisperse solution of N-doped GQDs has been obtained with particles size ca. similar to 10.9 +/- 1.3 nm. UV-Vis spectroscopy studies of the interactions between the N-doped GQDs and calf thymus DNA (CT-DNA) showed that the compound interact with CT-DNA via both intercalative and electrostatic binding. The DNA cleavage study showed that the N-doped GQDs cleaved DNA without any external agents. The antioxidant activity of N-doped GQDS was very active when compared to BHT. As the concentration of the compound increased, the antioxidant activity also increased. Cell viability assay demonstrated that the Ndoped GQDs showed cell viability (70%) when the concentration reached 200 mu g/mL for A549 and also MDA-MB-231, 150 mu g/mL for NIH-3T3 cell lines at 24 h incubation. N-doped GQDs were coated with Eudragit RS 100 and EphA2-siRNA was loaded. As a result of the studies on these formulations, it was concluded that there may be significant effects on A549 cells. The microscopy results revealed that N-doped GQDs was quickly internalized into the cell. Our novel N-doped-GQDs with siRNA are candidate for in situ tumor suppression via DNA and mRNA breakage. (C) 2019 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.
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    Öğe
    Synthesis and characterization of 2-aminoethylphosphonic acid-functionalized graphene quantum dots: biological activity, antioxidant activity and cell viability
    (Natl Inst Science Communication-Niscair, 2020) Yapar, Gonul; Senel, Behiye; Demir, Neslihan; Yıldız, Mustafa
    A facile, environmentally friendly one-step reaction for the preparation of luminescent N-doped graphene quantum dots (GQDs) involving a hydrothermal reaction between citric acid and 2-aminoethylphosphonic acid has been designed. Graphene quantum dots have been characterized by UV-visible absorption, FTIR spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and dynamic light scattering (DLS) techniques. Furthermore, the biological activity of the GQDs has been studied. UV-visible spectroscopy studies of the interactions between the GQDs and calf thymus DNA (CT-DNA) showed that the compound interacts with CT-DNA via intercalative binding. DNA cleavage study showed that the GQDs cleaved DNA oxidatively. In addition, antioxidant activity of N-doped GQDs was measured using the DPPH method. As the concentration of the compound increased, the antioxidant activity also has increased. According to cell viability analyses results, the N-doped GQDs showed cell viability (70%) when the concentration reaches 228 mu g/mL for A549, 200 mu g/mL for MDA-MB-231 and 140 mu g/mL for NIH-3T3 cell lines with 24 h incubation.