Intra-molecular Structural Change of PAMAM Dendrimers in Aqueous Solutions Revealed by Small Angle Neutron Scattering
- National Institute of Standards and Technology (NIST)
- ORNL
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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences; Spallation Neutron Source
- Sponsoring Organization:
- SC USDOE - Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 979183
- Journal Information:
- Journal of Physical Chemistry B, Journal Name: Journal of Physical Chemistry B Journal Issue: 5 Vol. 114; ISSN 1520-6106
- Country of Publication:
- United States
- Language:
- English
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