Semiflexible polymer rings on topographically and chemically structured surfaces

TL;DR

This paper explores the equilibrium shapes of semiflexible polymer rings, like circular DNA, on structured surfaces, revealing diverse morphologies and transition behaviors influenced by surface patterns and physical parameters.

Contribution

It provides a comprehensive classification and bifurcation analysis of polymer ring morphologies on striped surfaces, including complex multi-stripe geometries.

Findings

Identified four main equilibrium shapes for polymer rings on striped surfaces.

Mapped the bifurcation diagram as a function of length and adhesion-to-bending ratio.

Observed cascade transitions in complex multi-stripe geometries.

Abstract

We investigate morphologies of semiflexible polymer rings, such as circular DNA, which are adsorbed onto topographically or chemically structured substrate surfaces. We classify all equilibrium morphologies for two striped surface structures, (i) topographical surface grooves and (ii) chemically structured surface domains. For both types of stripes, we find four equilibrium shapes: a round toroidal and a confined elongated shape as well as two shapes containing bulges. We determine the complete bifurcation diagram of these morphologies as a function of their contour length and the ratio of adhesive strength to bending rigidity. For more complex geometries consisting of several stripes we find a cascade of transitions between elongated shapes. Finally, we compare our findings to ring condensation by attractive interactions.