Monodisperse self-assembly in a model with protein-like interactions

TL;DR

This study models protein-like interactions in patchy particles to understand self-assembly, revealing optimal conditions for forming complete, well-structured shells like viral capsids through thermodynamic and kinetic regulation.

Contribution

It introduces a minimal model with specific interactions that captures the thermodynamics and kinetics of protein shell assembly, highlighting the importance of free energy barriers and interaction specificity.

Findings

Robust assembly of target structures across parameter space.

Optimal assembly occurs near a free energy barrier that controls nucleation.

Torsional interactions prevent disordered aggregates and kinetic traps.

Abstract

We study the self-assembly behaviour of patchy particles with `protein-like' interactions that can be considered as a minimal model for the assembly of viral capsids and other shell-like protein complexes. We thoroughly explore the thermodynamics and dynamics of self assembly as a function of the parameters of the model and find robust assembly of all target structures considered. Optimal assembly occurs in the region of parameter space where a free energy barrier regulates the rate of nucleation, thus preventing the premature exhaustion of the supply of monomers that can lead to the formation of incomplete shells. The interactions also need to be specific enough to prevent the assembly of malformed shells, but whilst maintaining kinetic accessibility. Free-energy landscapes computed for our model have a funnel-like topography guiding the system to form the target structure, and show that the torsional component of the interparticle interactions prevents the formation of disordered aggregates that would otherwise act as kinetic traps.