@article{ISI:000242974300017,
 abstract = {We have performed similar to 20-40 ns of molecular dynamics (MD)
simulations for the generation 8 PAMAM dendrimer in explicit water under
varying pH conditions to study the structure of the dendrimer (similar
to 156 738 atoms at low pH). This is the first report of such a long MD
simulation of a larger generation PAMAM dendrimer including the effect
of salt and counterions with explicit water molecules. We find that
changing the pH from a high value (similar to 12) to a low value
(similar to 3) changes the radius of gyration from R-g = 37.8 to 43.1 A
(increasing by 13%). We also find significant back-folding of the
primary amines and a large amount of water penetration inside the
polymer. The increase in size with decrease in pH is consistent with our
earlier studies on G3-G6 and agrees with the Monte Carlo theory by Welch
and Muthukumar of G8 (Macromolecules, 1998, 31, 5892) and the
experiments on G5 and G8 PAMAM dendrimer by Topp et al. (Macromolecules,
1999, 32, 7232). However, these results disagree dramatically with the
interpretations of SANS experiments of G8 PAMAM dendrimers by Nisato et
al. (Macromolecules, 2000, 33, 4172) who observe no change in the size
of the dendrimer with variations of solution pH and ionic strength. We
assume that the disagreement might arise from neglecting nonspherical
shape, penetration of water and ions into the core, and aggregation, all
of which might depend on pH.},
 author = {Maiti, Prabal K. and Goddard, III, William A.},
 doi = {10.1021/jp0622684},
 eissn = {1520-5207},
 issn = {1520-6106},
 journal = {JOURNAL OF PHYSICAL CHEMISTRY B},
 month = {DEC 28},
 number = {51},
 orcid-numbers = {Maiti, Prabal/0000-0002-9956-1136},
 pages = {25628-25632},
 researcherid-numbers = {Maiti, Prabal/B-6335-2009},
 times-cited = {78},
 title = {Solvent quality changes the structure of G8 PAMAM dendrimer, a
disagreement with some experimental interpretations},
 unique-id = {ISI:000242974300017},
 volume = {110},
 year = {2006}
}