Inferring spatial organization of bonds within adhesion clusters by exploiting fluctuations of soft interfaces

A.-S. Smith^1,2, S. F. Fenz³ and K. Sengupta⁴

¹  II. Institut für Theoretische Physik, Universität Stuttgart - Pfaffenwaldring 57, 70550 Stuttgart, Germany, EU
²  Institut für Theoretische Physik, Universität Erlangen-Nünberg - Staudtstrasse 7, 90158 Erlangen, Germany, EU
³  Institute of Bio- and Nanosystems (IBN-4), Research Centre Jülich - D-52425 Jülich, Germany, EU
⁴  CNRS, Aix-Marseille Université, CINaM UPR 3118, Campus de Luminy - 13288 Marseille Cedex 9, France, EU

Corresponding author: sengupta@cinam.univ-mrs.fr

Received: 24 September 2009
Accepted: 11 January 2010

Abstract

Detecting the organization of bonds within adhesion domains connecting two interacting membranes is, at present, extremely challenging. Herein we present a technique, based on Reflection Interference Contrast Microscopy, which uses spontaneous thermal fluctuations of a soft interface as a tool to identify the organization of specific ligand-receptor bonds. The key is a time-resolved analysis of micro-interferometric data that systematically quantifies fluctuations and enables the detection of their suppression due to the formation of bonds, which, in turn, allows the identification of the bond organization without the use of fluorescent labelling. The identification of a new type of bond organization characterized by sparsely distributed bonds, as well as detection of pinning centres of nanometric size is presented.