4 research outputs found

    Dynamics of Fullerene-Mediated Heat-Driven Release of Drug Molecules from Carbon Nanotubes

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    We have performed molecular dynamics (MD) simulations as a function of temperature to investigate the controlled release of multiple pyrazinamide (PZA) drug molecules encapsulated within single-wall carbon nanotube (SWCNT) mediated by fullerene (C<sub>60</sub>) fillers. The displacement of PZA by C<sub>60</sub> can be accounted to the comparatively higher π–π stacking between C<sub>60</sub>–SWCNT and PZA–SWCNT. The root-mean-square deviation (RMSD) provides definitive insight into drug release and simultaneous C<sub>60</sub> entrapment within the nanotube. The diffusion coefficient, variation of center of mass (COM), and energetic profiles at different temperatures suggest that the rate of diffusion of PZA increases with temperature. These results can be quite instrumental in providing details about the role of temperature on drug release from confined SWCNTs and aims at achieving the drug delivery regime

    Dynamics of Fullerene-Mediated Heat-Driven Release of Drug Molecules from Carbon Nanotubes

    No full text
    We have performed molecular dynamics (MD) simulations as a function of temperature to investigate the controlled release of multiple pyrazinamide (PZA) drug molecules encapsulated within single-wall carbon nanotube (SWCNT) mediated by fullerene (C<sub>60</sub>) fillers. The displacement of PZA by C<sub>60</sub> can be accounted to the comparatively higher π–π stacking between C<sub>60</sub>–SWCNT and PZA–SWCNT. The root-mean-square deviation (RMSD) provides definitive insight into drug release and simultaneous C<sub>60</sub> entrapment within the nanotube. The diffusion coefficient, variation of center of mass (COM), and energetic profiles at different temperatures suggest that the rate of diffusion of PZA increases with temperature. These results can be quite instrumental in providing details about the role of temperature on drug release from confined SWCNTs and aims at achieving the drug delivery regime

    Hierarchical Self-Assembly of Noncanonical Guanine Nucleobases on Graphene

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    Self-assembly characterizes the fundamental basis toward realizing the formation of highly ordered hierarchical heterostructures. A systematic approach toward the supramolecular self-assembly of free-standing guanine nucleobases and the role of graphene as a substrate in directing the monolayer assembly are investigated using the molecular dynamics simulation. We find that the free-standing bases in gas phase aggregate into clusters dominated by intermolecular H-bonds, whereas in solvent, substantial screening of intermolecular interactions results in π-stacked configurations. Interestingly, graphene facilitates the monolayer assembly of the bases mediated through the base–substrate π–π stacking. The bases assemble in a highly compact network in gas phase, whereas in solvent, a high degree of immobilization is attributed to the disruption of intermolecular interactions. Graphene-induced stabilization/aggregation of free-standing guanine bases appears as one of the prerequisites governing molecular ordering and assembly at the solid/liquid interface. The results demonstrate an interplay between intermolecular and π-stacking interactions, central to the molecular recognition, aggregation dynamics, and patterned growth of functional molecules on two-dimensional nanomaterials

    Amino-Acid-Conjugated Gold Clusters: Interaction of Alanine and Tryptophan with Au<sub>8</sub> and Au<sub>20</sub>

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    The stability and electronic properties of gold (Au) clusters interacting with the amino acids alanine (Ala) and tryptophan (Trp) in their canonical and zwitterionic configurations were investigated using first-principles density functional theory (DFT). We found that the geometrical structures of the Au clusters and the polarities of the amino acids determine the nature of the interactions in the gas and solvent phases. In the gas phase, the Au<sub>8</sub> (<i>D</i><sub>4<i>h</i></sub>) and Au<sub>20</sub> (<i>T</i><sub><i>d</i></sub>) clusters prefer single-site interactions through the amine group for the canonical amino acids, whereas in the solvent phase, the carboxylic site is preferred for the zwitterionic amino acids. The limited screening of the intermolecular interactions introduced by the solvent medium for the canonical forms of Ala and Trp conjugated with the Au<sub><i>n</i></sub> complexes suggests that the bonding is primarily covalent in nature. The screening is significantly more pronounced for the zwitterionic complexes for which the electrostatic interactions dominate. The cluster sizes and configurations define the extent of the interactions and the overall stability of the complexes. The structures of the Au<sub><i>n</i></sub> clusters govern the charge distribution and electrostatic potential, directing the selectivity toward the preferential binding sites with the Ala and Trp amino acids
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