Kinetics of aggregation of an anisotropic model of self-assembling molecules.

Abstract

We study the kinetics of aggregation of a two site model of interacting spherical molecules. A given site on one molecule can interact with one or more sites on other neighboring molecules. The sites represent the result of a simple coarse graining of putative amino acid residues or two specifically designed sites on a colloidal particle. We study the kinetics and equilibrium morphology for a fixed angle between the two sites, for several angles between 30° and 150°. In the model, the sites interact via an attractive Asakura-Oosawa potential and the molecules have the usual hard sphere repulsion interaction. We find a transition from a micelle-like morphology at small angles to a rod-like morphology at intermediate angles and to a gel-like structure at values of the angle greater than about ninety degrees. However, at 150 degrees, after a long induction time during which there is no aggregation, we observe a nucleation and growth process that leads to a final spherical-like aggregate. Our results show that this angle is a control parameter for the kinetics and equilibrium properties of the system.