Incorporation of macromolecules into polyelectrolyte micro- and nanocapsules via surface controlled precipitation on colloidal particles

A novel approach to incorporate different polymers into micro- and nanocapsules fabricated by means of layer-by-layer (LbL) adsorption of oppositely charged polyelectrolytes on colloidal particles is proposed. This method comprises two stages. At first, the polymers, which are supposed to be incorporated, precipitate on the surface of colloidal particles. This can be done either by complexation of polyelectrolytes with multivalent ions or by adding miscible non-solvents. Then stable LbL assembled polyelectrolyte shells are formed. After core decomposition the inner polymer molecules are released from the wall but captured by the outer shell and floating in the capsule interior. The possibilities to encapsulate a wide class of charged and non-charged polymers were demonstrated on such examples as sodium poly(styrene sulfonate) as a polyanion, poly(allylamine hydrochloride) as a polycation and Dextrane as non-charged water soluble polymer. (C) 2002 Elsevier Science B.V. All rights reserved.