4 research outputs found
Dynamics of Fullerene-Mediated Heat-Driven Release of Drug Molecules from Carbon Nanotubes
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
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
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>
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