Effect of pH and generation on structural properties of Poly(amidoamine) dendrons studied by molecular dynamics simulations

Kyung-Hoon Lee, Inhan Lee, James R. Baker, Jr., Mark M. Banaszak Holl

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Abstract

Molecular dynamics (MD) simulations on G3 poly(amidoamine) (PAMAM) dendrons bearing an alkyne focal point were carried out at three different pH levels and with explicit water and counterions to obtain appropriate simulation conditions and validity for waterless simulations. We find that charged dendron simulation results with distance-dependent dielectric constant without nonbonded cutoff distance are most similar to the ones in explicit water and counterions. Structural changes of PAMAM dendrons and focal point accessibility are understood as functions of pH and dendron generation using MD simulations with the long-range interaction parameters. The simulation results indicate that the radii of gyration of the G3 and G5 dendrons at low pH (≤ 4) increase ∼67% as compared with those at high pH (≥ 10) and neutral pH (∼7). The dendron structures exhibit an increasingly hollow interior as pH level decreases. The dendron focal point remained accessible for all generations and pH values studied.

Original languageEnglish
Pages (from-to)127-136
Number of pages10
JournalJournal of Computational and Theoretical Nanoscience
Volume9
Issue number1
DOIs
Publication statusPublished - 1 Jan 2012
Externally publishedYes

Keywords

  • Alkyne focal point
  • Binary nanodevices
  • Molecular dynamics simulations
  • PAMAM dendrons

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