Journal Article

PreJuSER-12063

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png pH Responsiveness of Polyelectrolyte Dendrimers: A Dynamical Perspective

Li, X. ; Zamponi, M.FZJ* ; Hong, K. ; Porcar, L. ; Shew, C.-Y. ; Jenkins, T. ; Liu, E. ; Smith, G. S. ; Herwig, K. W. ; Liu, Y. ; Chen, W.-R.

2011
Royal Society of Chemistry (RSC) Cambridge

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Please use a persistent id in citations: http://hdl.handle.net/2128/7258  doi:10.1039/C0SM00671H

Abstract: A combined quasi-elastic neutron scattering (QENS) and high-resolution solution NMR spectroscopy study was conducted to investigate the internal dynamics of aqueous (D2O) G5 PAMAM dendrimer solutions as a function of molecular protonation at room temperature. Localized motion of the dendrimer segments was clearly exhibited in the QENS data analysis while the global, center-of-mass translational diffusion was measured by NMR. Our results unambiguously demonstrate an increased rapidity in local scale (similar to 3 angstrom) motion upon increasing the molecular protonation. This is contrary to an intuitive picture that increased charge stiffens the dendrimer segments thereby inhibiting local motion. These charge-induced changes may be a result of interactions with the surrounding counterions and water molecules as the segments explore additional intra-dendrimer volume made available by slight electrostatic swelling and redistribution of mass in the dendrimer interior. This observation is relevant to development of a microscopic picture of dendrimer-based packages as guest-molecule delivery vehicles because reorganization of the confining dendrimer segments must be a precursor to guest-molecule release.

Keyword(s): J

Note: This research at Oak Ridge National Laboratory's SNS was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. CNMS is sponsored at ORNL by the Division of Scientific User Facilities, U.S. Department of Energy.

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Contributing Institute(s):

1. Streumethoden (PGI-4)
2. Neutronenstreuung (ICS-1)
3. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)

Research Program(s):

1. BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung (P45)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Appears in the scientific report 2011

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