Abstract
Results of recent studies on polyelectrolyte complexes formed by both oppositely charged synthetic polyions and natural polyelectrolytes (proteins, enzymes, nucleic acids) are summarised. The properties of these complexes and the phase behaviour of their solutions are shown to obey general trends found in the studies of co-operative interpolyelectrolyte interactions. The principles of functioning of polyelectrolyte complexes that underlie the self-assembly of complexes in solution and determine the ability of the complexes to retain stability over a specified broad range of changes in external conditions and then to quickly and reversibly respond with high sensitivity to changes in the environment by changing their molecular characteristics and phase state are considered. The successful use of the results of fundamental research of (bio)polyelectrolyte complexes for solving topical problems of biotechnology, materials science and medicine are demonstrated.