Eur. Phys. J. E (2008) 26: 205-216
https://doi.org/10.1140/epje/i2007-10317-x

ISMC-2007

Key role of receptor density in colloid/cell specific interaction: a quantitative biomimetic study on giant vesicles

¹ Université Pierre et Marie Curie, Laboratoire PhysicoChimie Curie, Paris, France
² Université Bordeaux 1, Centre de Recherche Paul Pascal, av. du Docteur Schweitzer, 33000, Pessac, France
³ UPR 8641 Centre de Recherche Paul Pascal, CNRS, UMR 168 Laboratoire PhysicoChimie Curie, UMR 144 Compartimentation et dynamique cellulaires, Paris, France
⁴ Centre de Recherche, Institut Curie, 26 Rue d'Ulm, 75248, Paris Cedex 05, France

Received: 26 September 2007
Accepted: 19 March 2008
Published online: 15 May 2008

Abstract

This paper presents an experimental study of the adsorption of colloids on model membranes mediated by specific ligand-receptor interactions. The colloids consist of lipid multilamellar liposomes (spherulites) functionalized with the B-subunit of Shiga Toxin (STxB), while the membranes are lipid Giant Unilamellar Vesicles (GUV) containing STxB lipid receptor, Globotriaosylceramide (Gb3). Through confocal microscopy and flow cytometry, we show the specificity of the adsorption. Moreover, we show that flow cytometry can be used to efficiently quantify the kinetics of colloid adsorption on GUVs with very good statistics. By varying the bulk colloid concentration and receptor density in the membrane, we point out the existence of an optimum Gb3 density for adsorption. We propose that this optimum corresponds to a transition between reversible colloid adsorption at low Gb3 density and irreversible adsorption, and likely spherulite fusion, at high density. We compare our results both to STxB-colloids adhering on living cells and to free STxB proteins interacting with GUVs containing Gb3. This biomimetic system could be used for a quantitative evaluation of the early stage of virus infection or drug delivery.