Molecular dynamics study of charged dendrimers in salt-free solution: Effect of counterions

A.A. Gurtovenko, S.V. Lyulin, M. Karttunen, I. Vattulainen

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    70 Citations (Scopus)
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    Abstract

    Polyamidoamine dendrimers, being protonated under physiological conditions, represent a promising class of nonviral, nanosized vectors for drug and gene delivery. We performed extensive molecular dynamics simulations of a generic model dendrimer in a salt-free solution with dendrimer’s terminal beads positively charged. Solvent molecules as well as counterions were explicitly included as interacting beads. We find that the size of the charged dendrimer depends nonmonotonically on the strength of electrostatic interactions demonstrating a maximum when the Bjerrum length equals the diameter of a bead. Many other structural and dynamic characteristics of charged dendrimers are also found to follow this pattern. We address such a behavior to the interplay between repulsive interactions of the charged terminal beads and their attractive interactions with oppositely charged counterions. The former favors swelling at small Bjerrum lengths and the latter promotes counterion condensation. Thus, counterions can have a dramatic effect on the structure and dynamics of charged dendrimers and, under certain conditions, cannot be treated implicitly.
    Translated title of the contributionMolecular dynamics study of charged dendrimers in salt-free solution: Effect of counterions
    Original languageEnglish
    Pages (from-to)pp. 094904-1-8
    Number of pages8
    JournalJournal of Chemical Physics
    Volume124
    Issue number9, 094904
    DOIs
    Publication statusPublished - 2006
    Publication typeA1 Journal article-refereed

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