Competition between a macroion and a polyelectrolyte in complexation with an oppositely charged polyelectrolyte

The competition between a spherical macroion and a polyelectrolyte in complexation with an oppositely charged flexible polyelectrolyte has been studied by means of Monte Carlo simulations. A simple model system with focus on the electrostatic interactions has been used to investigate under what conditions the macroion in a polyelectrolyte-macroion complex (excess of polyelectrolyte charges) is exchanged with a polyelectrolyte. It is shown that the macroion is released when the charge of the added polyelectrolyte equals or exceeds that of the polyelectrolyte in the complex. The effect of the polyelectrolyte length, flexibility, and linear charge density on the macroion release has been investigated.