Controlling adsorption of semiflexible polymers on planar and curved substrates

TL;DR

This study investigates how polymer stiffness and substrate curvature influence the adsorption threshold of semiflexible polymers like DNA, revealing that both factors can be tuned to control adsorption behavior.

Contribution

The paper introduces a comprehensive analysis combining simulations and analytical methods to show how polymer stiffness and substrate curvature affect adsorption thresholds.

Findings

Adsorption threshold is maximized when polymer persistence length matches potential range.

Surface curvature can modulate the critical potential strength for adsorption.

Optimal polymer stiffness for adsorption can be achieved by tuning substrate curvature.

Abstract

We study the adsorption of semiflexible polymers such as polyelectrolytes or DNA on planar and curved substrates, e.g., spheres or washboard substrates via short-range potentials using extensive Monte-Carlo simulations, scaling arguments, and analytical transfer matrix techniques. We show that the adsorption threshold of stiff or semiflexible polymers on a planar substrate can be controlled by polymer stiffness: adsorption requires the highest potential strength if the persistence length of the polymer matches the range of the adsorption potential. On curved substrates, i.e., an adsorbing sphere or an adsorbing washboard surface, the adsorption can be additionally controlled by the curvature of the surface structure. The additional bending energy in the adsorbed state leads to an increase of the critical adsorption strength, which depends on the curvature radii of the substrate structure. For an adsorbing sphere, this gives rise to an optimal polymer stiffness for adsorption, i.e., a local minimum in the critical potential strength for adsorption, which can be controlled by curvature. For two- and three-dimensional washboard substrates, we identify the range of persistence lengths and the mechanisms for an effective control of the adsorption threshold by the substrate curvature.