  Mechanical interactions between biological cells may be mediated by secreted
products, making them dependent on the local particle density. Here, we explore
the generic physics of density-dependent attractive interactions. We show using
Brownian dynamics simulations that density-dependent interactions can produce
interesting phase separation behaviour including control of aggregate size
during a spinodal decomposition-like separation process. We show that these
results are generic using continuum modelling of the appropriate Cahn-Hilliard
equation. Our study suggests that density-dependent interactions can provide a
generic mechanism for control of aggregate size during phase separation.
