Interactions between charged rods near salty surfaces
R. Menes1 - N. Grønbech-Jensen2 - P.A. Pincus1
1 Materials Research Laboratory, University of California,
Santa Barbara, CA 93106, USA
2 Department of Applied Science, University of California,
Davis, CA 95616, USA
NERSC, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
menes@mrl.ucsb.edu
Received 28 September 1999
Abstract
Using both theoretical modeling and computer simulations we study a model system for
DNA interactions in the vicinity of charged membranes. We focus on the polarization
of the mobile charges in the membranes due to the nearby charged rods (DNA) and the resulting
screening of their fields and inter-rod interactions. We find, both within a Debye-Hückel
model and in Brownian dynamics simulations, that the confinement of the mobile charges to
the surface leads to a qualitative reduction in their ability to screen the charged rods
to the degree that the fields and resulting interactions are not finite-ranged as in systems
including a bulk salt concentration, but rather decay algebraically and the screening effect
is more like an effective increase in the multipole moment of the charged rod.
PACS
87.68.+z Biomaterials and biological interfaces -
87.16.Dg Membranes bilayers and vesicles -
68.10.-m Fluid surfaces and fluid-fluid interfaces
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
