Advanced

NMR studies of molecular mobility in a DNA-amphiphile complex

Leal, Cecilia LU ; Topgaard, Daniel LU ; Martin, R W and Wennerström, Håkan LU (2004) In The Journal of Physical Chemistry Part B 108(39). p.15392-15397
Abstract
The molecular mobility in a hexagonal DNA-cationic surfactant complex is studied using H-1 and C-13 nuclear magnetic resonance spectroscopy. The charge-compensated complex can swell in water up to a content of approximately seven water molecules per charge. The NMR measurements show that in the dry state the alkyl chains of the surfactant have the properties of a disordered solid with internal motions of sufficient amplitude to substantially narrow the H-1 resonance line from the rigid lattice limit. As water is introduced, there is an increase in molecular motion resulting in further narrowing of the signal. In the fully swollen system, the signal is narrower than that observed for a normal hexagonal liquid crystalline phase with the same... (More)
The molecular mobility in a hexagonal DNA-cationic surfactant complex is studied using H-1 and C-13 nuclear magnetic resonance spectroscopy. The charge-compensated complex can swell in water up to a content of approximately seven water molecules per charge. The NMR measurements show that in the dry state the alkyl chains of the surfactant have the properties of a disordered solid with internal motions of sufficient amplitude to substantially narrow the H-1 resonance line from the rigid lattice limit. As water is introduced, there is an increase in molecular motion resulting in further narrowing of the signal. In the fully swollen system, the signal is narrower than that observed for a normal hexagonal liquid crystalline phase with the same surfactant. This shows that the alkyl chains are packed with a degree of disorder that is higher than in the corresponding liquid crystalline surfactant system, reflecting the aggregate deformations induced by the requirement of charge matching with DNA. Furthermore, the translational diffusional motion of the surfactant molecule is slower than D < 10(-13) m(2)/s, while for the water molecules we observe D going from 1 x 10(-11)m(2)/ s at 5 water molecules per base pair to 2 x 10(-10) m(2)/s at the swelling limit of 27 waters per base pair. The DNA remains solid throughout the hydration range. By combining the NMR observations with the thermodynamic characterization of the system by Leal et al.(1) we arrive at a detailed description of the molecular organization in the complex between DNA and the single chain cationic surfactant hexadecyltrimethylammonium, CTA. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
108
issue
39
pages
15392 - 15397
publisher
The American Chemical Society
external identifiers
  • wos:000224070200083
  • scopus:6344292462
ISSN
1520-5207
DOI
10.1021/jp0480495
language
English
LU publication?
yes
id
4323f5cf-2c09-467b-b9b3-fbfc0e0d7f8b (old id 153955)
date added to LUP
2007-07-11 15:36:24
date last changed
2017-10-29 04:22:03
@article{4323f5cf-2c09-467b-b9b3-fbfc0e0d7f8b,
  abstract     = {The molecular mobility in a hexagonal DNA-cationic surfactant complex is studied using H-1 and C-13 nuclear magnetic resonance spectroscopy. The charge-compensated complex can swell in water up to a content of approximately seven water molecules per charge. The NMR measurements show that in the dry state the alkyl chains of the surfactant have the properties of a disordered solid with internal motions of sufficient amplitude to substantially narrow the H-1 resonance line from the rigid lattice limit. As water is introduced, there is an increase in molecular motion resulting in further narrowing of the signal. In the fully swollen system, the signal is narrower than that observed for a normal hexagonal liquid crystalline phase with the same surfactant. This shows that the alkyl chains are packed with a degree of disorder that is higher than in the corresponding liquid crystalline surfactant system, reflecting the aggregate deformations induced by the requirement of charge matching with DNA. Furthermore, the translational diffusional motion of the surfactant molecule is slower than D &lt; 10(-13) m(2)/s, while for the water molecules we observe D going from 1 x 10(-11)m(2)/ s at 5 water molecules per base pair to 2 x 10(-10) m(2)/s at the swelling limit of 27 waters per base pair. The DNA remains solid throughout the hydration range. By combining the NMR observations with the thermodynamic characterization of the system by Leal et al.(1) we arrive at a detailed description of the molecular organization in the complex between DNA and the single chain cationic surfactant hexadecyltrimethylammonium, CTA.},
  author       = {Leal, Cecilia and Topgaard, Daniel and Martin, R W and Wennerström, Håkan},
  issn         = {1520-5207},
  language     = {eng},
  number       = {39},
  pages        = {15392--15397},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {NMR studies of molecular mobility in a DNA-amphiphile complex},
  url          = {http://dx.doi.org/10.1021/jp0480495},
  volume       = {108},
  year         = {2004},
}