Issue
EPL
Volume 84, Number 2, October 2008
Article Number 26004
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/84/26004
Published online 06 October 2008
EPL, 84 (2008) 26004
DOI: 10.1209/0295-5075/84/26004

Effective surface interactions mediated by adhesive particles

B. Różycki, R. Lipowsky and T. R. Weikl

Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems 14424 Potsdam, Germany, EU

weikl@mpikg.mpg.de

received 16 May 2008; accepted in final form 7 September 2008; published October 2008
published online 6 October 2008

Abstract
In biomimetic and biological systems, interactions between surfaces are often mediated by adhesive molecules, nanoparticles, or colloids dispersed in the surrounding solution. We present here a general, statistical-mechanical model for two surfaces that interact via adhesive particles. The effective, particle-mediated interaction potential of the surfaces is obtained by integrating over the particles' degrees of freedom in the partition function. Interestingly, the effective adhesion energy of the surfaces exhibits a maximum at intermediate particle concentrations, and is considerably smaller both at low and high concentrations. The effective adhesion energy corresponds to a minimum in the interaction potential at surface separations slightly larger than the particle diameter, while a secondary minimum at surface contact reflects depletion interactions. Our results can be generalized to surfaces with specific receptors for solute particles, and have direct implications for the adhesion of biomembranes and for phase transitions in colloidal systems.

PACS
68.43.De - Statistical mechanics of adsorbates.
05.20.-y - Classical statistical mechanics.
68.35.Np - Adhesion.

© EPLA 2008