pH-controlled macromolecule encapsulation in and release from polyelectrolyte multilayer nanocapsules

Communication: pH-Controlled encapsulation in and release of macromolecules from polyelectrolyte capsules of a few microns in diameter is demonstrated . Capsules were prepared via alternating adsorption of the oppositely charg ed polymers poly(allylamine hydrochloride) and poly(styrene sulfonate) onto decomposable melamin formaldehyde cores. The capsules were open for macrom olecules at pH values below 6 and closed at pH > 8. Permeation and encapsulation of FITC-dextran (MW 75 000) into polyelectroly te multilayer capsules. Top: pH 10, center: pH 3, bottom: pH increased to 1 0 after the capsules were loaded with FITC-dextran at pH 3. The bulk FITC-d extran was removed by washings at pH 10.