Membrane filtration for microencapsulation and microcapsules fabrication by layer-by-layer polyelectrolyte adsorption.

Layer-by-layer polyelectrolyte adsorption at colloid particle surfaces as well as the removal of the core latex to obtain multilayer microcapsules is conducted by means of membrane filtration. As target particles for adsorption we use nonsoluble polystyrene sulfate latex, soluble melamine formaldehyde resin latex, and decomposable glutaraldehyde fixed human red blood cells. The materials adsorbed are poly(allylamine hydrochloride), poly(styrenesulfonate), poly(diallyldimethylammonium chloride), chitosan, and chitosansulfate. The coating process is carried out under different membrane filtration conditions with respect to the pressure regime, the filter materials, and the stirring conditions. We characterize the prepared multilayers at the particle surface or in the microcapsule (shell) form by atomic force microscopy, confocal laser scanning microscopy, transmission electron microscopy, single-particle light scattering, and electrophoresis. The quality, performance, and yield of the presented method are c...