VladimirSamuilov
Electrostatic Interaction of Long DNA
Molecules with Solid State Surfaces
Vladimir Samuilov, Department of Physics, St. John’s
College of Liberal Arts and Sciences
Abstract: During electric transport
at low buffer concentration strong electrostatic interaction of DNA
molecules with substrate initiates a number of phenomena, such as
the electro-hydrodynamic instability, partial adsorption at the
buffer-semiconductor interface and stretching DNA with the electric
field. The electric double layer is responsible for a velocity
profile of the electroosmotic flow near the surface.
Long DNA molecules at the silicon substrate–buffer solution
interface are very interesting objects to study electric transport
along the surfaces. The system (DNA-substrate-electric field in the
buffer solution) is very complicated. Due to the strong
electrostatic interaction of DNA with the substrate, the image
charge is generated, and the physical adsorption takes place.
Within a surface DNA is entropically recoiled due to
electrostatic adsorption. The electroosmotic flow strongly depends
on the electric field. If the electric field is high enough, DNA
could be de-trapped and forms a compact coil. This behavior is
considered as an inverse mechanism of entropy trapping due to
confined constrictions. In the case of the surface, DNA is recoiled
and trapped in the stretched configuration in the deep energetic
barrier by Si surface due to the strong electrostatic interaction.
If the energy of the field is enough to overcome the barrier, DNA
is detached. The Si surface could be considered as an analog of the
entropic recoiling nanostructure.