Trains, tails and loops of partially adsorbed semi-flexible filaments

TL;DR

This study combines experiments and simulations to analyze how semi-flexible polymers adsorb onto surfaces, revealing that filament stiffness influences desorption mechanisms and providing universal laws for adsorption behavior.

Contribution

It introduces a combined experimental and computational approach to understand the adsorption-desorption transition of semi-flexible polymers, highlighting the role of filament stiffness and configurational space.

Findings

Desorption driven by fluctuating tails in stiff filaments

Universal laws for adsorption-desorption transition scaling

Quantitative agreement between experiments and simulations

Abstract

Polymer adsorption is a fundamental problem in statistical mechanics that has direct relevance to diverse disciplines ranging from biological lubrication to stability of colloidal suspensions. We combine experiments with computer simulations to investigate depletion induced adsorption of semi-flexible polymers onto a hard-wall. Three dimensional filament configurations of partially adsorbed F-actin polymers are visualized with total internal reflection fluorescence microscopy. This information is used to determine the location of the adsorption/desorption transition and extract the statistics of trains, tails and loops of partially adsorbed filament configurations. In contrast to long flexible filaments which primarily desorb by the formation of loops, the desorption of stiff, finite-sized filaments is largely driven by fluctuating filament tails. Simulations quantitatively reproduce our experimental data and allow us to extract universal laws that explain scaling of the adsorption-desorption transition with relevant microscopic parameters. Our results demonstrate how the adhesion strength, filament stiffness, length, as well as the configurational space accessible to the desorbed filament can be used to design the characteristics of filament adsorption and thus engineer properties of composite biopolymeric materials.