Fig. 1
Effect of a nanofunnel on DNA threading into a nanochannel. a Cartoon illustrating the electrohydrodynamic (red arrow) and entropic (green arrow) forces affecting the leading portion of the DNA molecule as it is electrophoretically pulled into a nanochannel under an applied bias, ΔV. b These forces and an additional osmotic gradient force (blue arrows) act on the entire DNA molecule as a result of the extended high electric field region and the confining effects of the nanofunnel (in contrast to the smaller portion of segments affected in (a)). At the wide entrance to the nanofunnel (its mouth), the electrohydrodynamic force is greater than the entropic force. The osmotic gradient force acts as an “electro-osmotic piston,” providing further assistance for DNA entry into the nanochannel. The electric field strengths (relative to the electric field strength in the nanochannel, E Channel) are indicated using a logarithmic color scale for clarity
