Depletion forces near curved surfaces

TL;DR

This paper uses density functional theory to analyze how curvature affects depletion forces on a large sphere near spherical surfaces, revealing slow convergence to flat wall behavior and implications for membrane interactions.

Contribution

It provides a detailed theoretical analysis of curvature effects on depletion potentials, extending understanding beyond flat surfaces using density functional theory.

Findings

Depletion potential depends on curvature and packing fraction.

Slow convergence to flat wall limit as radius increases.

Results relate to experimental observations of membrane forces.

Abstract

Based on density functional theory the influence of curvature on the depletion potential of a single big hard sphere immersed in a fluid of small hard spheres with packing fraction \eta_s either inside or outside of a hard spherical cavity of radius R_c is calculated. The relevant features of this potential are analyzed as function of \eta_s and R_c. There is a very slow convergence towards the flat wall limit R_c \to \infty. Our results allow us to discuss the strength of depletion forces acting near membranes both in normal and lateral directions and to make contact with recent experimental results.