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Title: Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering

Abstract

Small-angle neutron scattering (SANS) experiments were carried out to investigate the structure of aqueous (D2O) G4 PAMAM dendrimer solutions as a function of molecular protonation and dendrimer concentration. Our results indicate unambiguously that, although the radius of gyration RG remains nearly invariant, the dendrimer radial density profile (r) decreases in the dendrimer core with a continuous increase in protonation. This discovery also suggests that RG, which is commonly adopted by numerous simulation and experimental works in describing the global dendrimer size, is not suitable as the index parameter to characterize the dendrimer conformation change. We also found that RG and (r), for dendrimers dissolved in both neutral and acidified solutions, remain nearly constant over the studied concentration range. We further demonstrate that the outcome of the widely used Guinier method is questionable for extracting RG in the concentration range studied. Our results reveal the polymer colloid structural duality as benchmarks for future experimental and theoretical studies and provide a critical step toward understanding drug encapsulation by ionic bonds.

Authors:
 [1];  [2];  [2];  [2];  [2];  [1];  [2]
  1. National Institute of Standards and Technology (NIST)
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
979183
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B
Additional Journal Information:
Journal Volume: 114; Journal Issue: 5; Journal ID: ISSN 1520-6106
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AQUEOUS SOLUTIONS; BENCHMARKS; COLLOIDS; DUALITY; ENCAPSULATION; NEUTRONS; POLYMERS; SCATTERING; SIMULATION

Citation Formats

Porcar, L., Hong, Kunlun, Butler, Paul D, Herwig, Kenneth W, Smith, Gregory Scott, Liu, Yun, and Chen, Wei-Ren. Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering. United States: N. p., 2010. Web. doi:10.1021/jp9064455.
Porcar, L., Hong, Kunlun, Butler, Paul D, Herwig, Kenneth W, Smith, Gregory Scott, Liu, Yun, & Chen, Wei-Ren. Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering. United States. https://doi.org/10.1021/jp9064455
Porcar, L., Hong, Kunlun, Butler, Paul D, Herwig, Kenneth W, Smith, Gregory Scott, Liu, Yun, and Chen, Wei-Ren. 2010. "Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering". United States. https://doi.org/10.1021/jp9064455.
@article{osti_979183,
title = {Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering},
author = {Porcar, L. and Hong, Kunlun and Butler, Paul D and Herwig, Kenneth W and Smith, Gregory Scott and Liu, Yun and Chen, Wei-Ren},
abstractNote = {Small-angle neutron scattering (SANS) experiments were carried out to investigate the structure of aqueous (D2O) G4 PAMAM dendrimer solutions as a function of molecular protonation and dendrimer concentration. Our results indicate unambiguously that, although the radius of gyration RG remains nearly invariant, the dendrimer radial density profile (r) decreases in the dendrimer core with a continuous increase in protonation. This discovery also suggests that RG, which is commonly adopted by numerous simulation and experimental works in describing the global dendrimer size, is not suitable as the index parameter to characterize the dendrimer conformation change. We also found that RG and (r), for dendrimers dissolved in both neutral and acidified solutions, remain nearly constant over the studied concentration range. We further demonstrate that the outcome of the widely used Guinier method is questionable for extracting RG in the concentration range studied. Our results reveal the polymer colloid structural duality as benchmarks for future experimental and theoretical studies and provide a critical step toward understanding drug encapsulation by ionic bonds.},
doi = {10.1021/jp9064455},
url = {https://www.osti.gov/biblio/979183}, journal = {Journal of Physical Chemistry B},
issn = {1520-6106},
number = 5,
volume = 114,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 2010},
month = {Fri Jan 01 00:00:00 EST 2010}
}