8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.56Wed 711:10-14:00Eye-lens protein mixtures as an ideal colloidal system:application to cataract diseaseGiuseppe Foffi, 1 Nicolas Dorsaz, 2 Peter Schurtenberger, 2 Anna Stradner, 3 andGeorge Thurston 41 Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Theoretical Physics (ITP),, EPFL SB ITP GR-FO, BSP 418 (B sciences physiques UNIL) 1015, Lausanne,Switzerland2 Department of Chemistry, Cambridge, United Kingdom3 Physical Chemistry Chemical Center Lund University, Lund, Sweden4 Rochester Institute of Technology, Rochester, United States of AmericaThe eye-lens is one of the few transparent organs in our body. It contains a high density proteinsolution that remains stable over the whole life and guarantees transparency. When this stabilityis disrupted, density or concentration fluctuations set in making the eye-lens opaque to light. Thisis the molecular origin of cataract disease. I will discuss the properties of a binary mixture ofcolloidal particles devised to mimic the behavior of this eye-lens proteins system. We develop acoarse grained approach in which each protein is modeled as colloidal particle based on neutronscattering experiments. Our model was validated by molecular dynamics simulations, reproducingthe scattering intensities. We showed that there exists a mutual attraction between the two species[1]. In particular, we discovered that the thermodynamics stability of the mixture depends stronglyon such mutual interaction. Moreover, we used thermodynamic perturbation theory to characterizethe mixture in the full parameter space [2]. The main result is that there is a very narrow rangeof values of the mutual attraction where the mixture is stable. In particular we can pass from ademixing to a condensation by varying this mutual attraction. We have also characterized the fullphase diagram calculating the tie-lines that can be directly related to the experimental results [3].This novel idea has revived the interest in binary mixtures of eye-lens [4] and our predictions havebeen confirmed investigating crystallins with point mutations [5].[1] A. Stradner, G. Foffi, N. Dorsaz, G. M. Thurston, and P. Schurtenberger Phys. Rev.Lett. 99, 198103 (2007).[2] N. Dorsaz, G. M. Thurston, A. Stradner, P. Schurtenberger and G. Foffi, J. Phys. Chem. B,113, 1693 (2009).[3] N. Dorsaz, G. M. Thurston, A. Stradner, P. Schurtenberger and G. Foffi, Soft Matter, 7, 1763(2011).[4] Y. Wang et al. , PNAS 107 13282 (2010).[5] Banerjee et al. , PNAS 108 574 (2011)56