Biomedical Engineering Reference
In-Depth Information
Fig. 11.24 (a) Experimental set-up. (b) Effective electric driving forces vs. voltage drops across
the solid membrane for different salt concentrations. (Adapted from [
34
]. Figures permitted by
Nature Physics)
Molecular dynamics simulations that can capture atomic-level details were per-
formed to characterize the effective charge
q
eff
of DNA in a solid-state nanopore [
37
].
Simulation results show that the effective driving force on DNA is independent of
the counterion-screened charge of DNA. Because of non-specific binding between
mono-valent ions and DNA, a typical residence time of such ions is only about 10 ps.
In an electric field, counterions near the DNA surface move in the field direction,
causing an electro-osmotic flow inside a nanopore (Fig.
11.25a
). Thus, the electric
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