Description: pH Responsiveness of Polyelectrolyte Dendrimers: A Dynamical Perspective

This title appears in the Scientific Report : 2011

pH Responsiveness of Polyelectrolyte Dendrimers: A Dynamical Perspective

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 segmen...

Personal Name(s):	Li, X.
	Zamponi, M. / Hong, K. / Porcar, L. / Shew, C.-Y. / Jenkins, T. / Liu, E. / Smith, G.S. / Herwig, K.W. / Liu, Y. / Chen, W.-R.
Contributing Institute:	JCNS; JCNS Neutronenstreuung; ICS-1 Streumethoden; PGI-4
Published in:	Soft matter, 7 (2011) S. 618 - 622
Imprint:	Cambridge Royal Society of Chemistry (RSC) 2011
Physical Description:	618 - 622
DOI:	10.1039/C0SM00671H
Document Type:	Journal Article
Research Program:	Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung
Series Title:	Soft Matter 7
Subject (ZB):	J
Link:	Get full text Published under German "Allianz" Licensing conditions on 2010-11-23. Available in OpenAccess from 2011-11-23
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1039/C0SM00671H in citations.
Please use the identifier: http://hdl.handle.net/2128/7258 in citations.

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.