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Calcium mediated interaction of calf-thymus DNA with monolayers of distearoylphosphtidylcholine: a neutron and Xray reflectivity study

Dabkowska, Aleksandra LU ; Talbot, Jonathan P. ; Cavalcanti, Leide ; Webster, John R. P. ; Nelson, Andrew ; Barlow, David J. ; Fragneto, Giovanna and Lawrence, M. Jayne (2013) In Soft Matter 9(29). p.7095-7105
Abstract
X-ray and neutron reflection studies, the latter in conjunction with contrast variation, have been combined to study the interaction of calf thymus DNA (ctDNA) with monolayers of distearoylphosphatidylcholine (DSPC) in the presence of 20 mM Ca2+ ions, at the air–liquid interface as a function of surface pressure (10, 20, 30 and 40 mN m−1). Analysis of the X-ray and neutron reflection data showed that, regardless of the surface pressure of the monolayer, a layer of ctDNA was present below the DSPC lipid head groups and that this ctDNA-containing layer (thickness [similar]12.5 to 15 Å) was separated from the DSPC head groups by a layer of water of [similar]9 Å thickness. The thickness of the ctDNA-containing layer was thinner than that... (More)
X-ray and neutron reflection studies, the latter in conjunction with contrast variation, have been combined to study the interaction of calf thymus DNA (ctDNA) with monolayers of distearoylphosphatidylcholine (DSPC) in the presence of 20 mM Ca2+ ions, at the air–liquid interface as a function of surface pressure (10, 20, 30 and 40 mN m−1). Analysis of the X-ray and neutron reflection data showed that, regardless of the surface pressure of the monolayer, a layer of ctDNA was present below the DSPC lipid head groups and that this ctDNA-containing layer (thickness [similar]12.5 to 15 Å) was separated from the DSPC head groups by a layer of water of [similar]9 Å thickness. The thickness of the ctDNA-containing layer was thinner than that reported for monolayers of cationic lipid at the air–water interface (18–25 Å) although in these monolayers no water layer separating the lipid head groups from the layer containing ctDNA has been reported. At all surface pressures the amount of ctDNA present in the layer was in the range 30–40% by volume. As no significant re-arrangement of the DSPC film was required to accommodate the presence of the ctDNA, this suggests that the distribution of charges in the lipid film matches well the charge spacing of ctDNA. Brewster angle microscopy measurements of DSPC on water in the absence of Ca2+ showed the presence of a continuous film containing small, regular shaped domains at all four surface pressures examined. When Ca2+ ions were present in the sub-phase, although the film was still continuous, the domains comprising the film were more irregular in appearance while the presence of Ca2+ ions and ctDNA resulted in the domains becoming smaller and more regularly packed on the surface. (Less)
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publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
9
issue
29
pages
7095 - 7105
publisher
Royal Society of Chemistry
external identifiers
  • scopus:84880006396
ISSN
1744-6848
DOI
10.1039/C3SM50350J
language
English
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no
id
3041f73a-b174-4d7c-89ee-d3f8f30351d5 (old id 4250667)
date added to LUP
2016-04-01 13:37:39
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2020-05-13 02:32:48
@article{3041f73a-b174-4d7c-89ee-d3f8f30351d5,
  abstract     = {X-ray and neutron reflection studies, the latter in conjunction with contrast variation, have been combined to study the interaction of calf thymus DNA (ctDNA) with monolayers of distearoylphosphatidylcholine (DSPC) in the presence of 20 mM Ca2+ ions, at the air–liquid interface as a function of surface pressure (10, 20, 30 and 40 mN m−1). Analysis of the X-ray and neutron reflection data showed that, regardless of the surface pressure of the monolayer, a layer of ctDNA was present below the DSPC lipid head groups and that this ctDNA-containing layer (thickness [similar]12.5 to 15 Å) was separated from the DSPC head groups by a layer of water of [similar]9 Å thickness. The thickness of the ctDNA-containing layer was thinner than that reported for monolayers of cationic lipid at the air–water interface (18–25 Å) although in these monolayers no water layer separating the lipid head groups from the layer containing ctDNA has been reported. At all surface pressures the amount of ctDNA present in the layer was in the range 30–40% by volume. As no significant re-arrangement of the DSPC film was required to accommodate the presence of the ctDNA, this suggests that the distribution of charges in the lipid film matches well the charge spacing of ctDNA. Brewster angle microscopy measurements of DSPC on water in the absence of Ca2+ showed the presence of a continuous film containing small, regular shaped domains at all four surface pressures examined. When Ca2+ ions were present in the sub-phase, although the film was still continuous, the domains comprising the film were more irregular in appearance while the presence of Ca2+ ions and ctDNA resulted in the domains becoming smaller and more regularly packed on the surface.},
  author       = {Dabkowska, Aleksandra and Talbot, Jonathan P. and Cavalcanti, Leide and Webster, John R. P. and Nelson, Andrew and Barlow, David J. and Fragneto, Giovanna and Lawrence, M. Jayne},
  issn         = {1744-6848},
  language     = {eng},
  number       = {29},
  pages        = {7095--7105},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Calcium mediated interaction of calf-thymus DNA with monolayers of distearoylphosphtidylcholine: a neutron and Xray reflectivity study},
  url          = {http://dx.doi.org/10.1039/C3SM50350J},
  doi          = {10.1039/C3SM50350J},
  volume       = {9},
  year         = {2013},
}