DNA confined in a two-dimensional strip geometry

Abstract

Semiflexible polymers characterized by the contour length $L$ and persistent length $\ell_p$ confined in a spatial region $D$ have been described as a series of ``{\em spherical blobs}'' and ``{\em deflecting lines}'' by de Gennes and Odjik for $\ell_p < D$ and $\ell_p \gg D$ respectively. Recently new intermediate regimes ({\em extended de Gennes} and {\em Gauss-de Gennes}) have been investigated by Tree {\em et al.} [Phys. Rev. Lett. {\bf 110}, 208103 (2013)]. In this letter we derive scaling relations to characterize these transitions in terms of universal scaled fluctuations in $d$-dimension as a function of $L,\ell_p$, and $D$, and show that the Gauss-de Gennes regime is absent and extended de Gennes regime is vanishingly small for polymers confined in a 2D strip. We validate our claim by extensive Brownian dynamics (BD) simulation which also reveals that the prefactor $A$ used to describe the chain extension in the Odjik limit is independent of physical dimension $d$ and is the same as previously found by Yang {\em et al.}[Y. Yang, T. W. Burkhardt, G. Gompper, Phys. Rev. E {\bf 76}, 011804 (2007)]. Our studies are relevant for optical maps of DNA stretched inside a nano-strip.