School Of Basic And Applied Sciences

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    Amino acid functionalized zinc oxide nanostructures for cytotoxicity effect and hemolytic behavior: Theoretical and experimental studies
    (Elsevier Ltd, 2017) Singh, Satvinder; Singh, Baljinder; Sharma, Prateek; Mittal, Anu; Kumar, Sanjeev; Saini, G.S.S.; Tripathi, S.K.; Singh, Gurinder; Kaura, Aman
    Blending of theoretical and experimental approach, provide an important strategy in designing the nanostructure at a microscopic level and helps in predicting the response of synthesized material towards inhibition of the growth of breast cancer cell. In this work, ab initio calculations using super cell approach are performed for three different amino acids (AAs)-Histidine (His), Arginine (Arg) and Aspartic acid (Asp) coated Zinc oxide (ZnO) nanostructures to explain the growth mechanism of nanoparticles (NPs) of different shapes. Based on the first principles calculations, we reveal that ZnO-AA (Arg and Asp) NPs results in rod like and ZnO-His NPs lead to tablet like configuration. Similar morphologies are fabricated using AAs through synthetic route. The effect of concentration ratio of reactants and pH has been studied. As synthesized samples, are characterized by using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and UV?Vis spectroscopy techniques. Based on the results, a plausible mechanism of formation of nanostructures has been proposed. The nanostructures with rod like morphology are found to be biocompatible with normal red blood cells and show cytotoxic effect as evaluated from hemolysis and cytotoxicity assays on breast (MCF-7, T47D, MDA-MB-231) & prostate cancer (PC-3) cell lines. ? 2017 Elsevier Ltd
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    Size dependent tunnel diode effects in gold tipped CdSe nanodumbbells
    (American Institute of Physics Inc., 2017) Saraf, Deepashri; Kumar, Ashok; Kanhere, Dilip; Kshirsagar, Anjali
    We report simulation results for scanning tunneling spectroscopy of gold-tipped CdSe nanodumbbells of lengths ?27 ? and ?78 ?. Present results are based on Bardeen, Tersoff, and Hamann formalism that takes inputs from ab initio calculations. For the shorter nanodumbbell, the current-voltage curves reveal negative differential conductance, the characteristic of a tunnel diode. This behaviour is attributed to highly localized metal induced gap states that rapidly decay towards the center of the nanodumbbell leading to suppression in tunneling. In the longer nanodumbbell, these gap states are absent in the central region, as a consequence of which zero tunneling current is observed in that region. The overall current-voltage characteristics for this nanodumbbell are observed to be largely linear near the metal-semiconductor interface and become rectifying at the central region, the nature being similar to its parent nanorod. The cross-sectional heights of these nanodumbbells also show bias-dependence where we begin to observe giant Stark effect features in the semiconducting central region of the longer nanodumbbell. ? 2017 Author(s).