Tube-like motion of ds-DNA in a nanoslit post array

Polymer reptation motion has been observed in polymer trapped in a porous network with pore size smaller than the chain Kuhn length. In this study, we directly observe the tube-like motion of DNA confined in nano-height hexagonal micropost arrays, where the post spacing is much larger than the Kuhn length. The chain length $N $dependence of DNA diffusivity $D$ exhibits the two-dimensional reptation scaling D $\sim \quad N^{-1.5}$. The tube-like motion results from confinement-induced attraction between DNA and the microposts. We also systematically investigate the transition of DNA-wall interaction from repulsion to attraction.