Variable on-demand release function of magnetoresponsive hybrid capsules

Magnetoresponsive hybrid capsules formed with polyelectrolytes, amphiphile bilayers and Fe3O4 nanoparticles were fabricated by a colloid-templating technique. Melamine-formaldehyde (MF) core particles with polyelectrolyte multilayer shell were prepared by layer-by-layer assembly. Fe3O4 nanoparticles were additionally deposited on the capsular surface. Hollow capsules were obtained by the removal of the MF core particles. Amphiphile bilayer was finally coated on the obtained hollow capsules. The deposition amount of the Fe3O4 nanoparticles is variable by changing the concentration of Fe3O4 dispersion using for preparation of capsules. Encapsulated dyes were released on-demand by irradiation with an alternating magnetic field, due to a phase transition in the amphiphile membrane, induced by heating of the magnetic nanoparticles. The release rate of the hybrid capsules was controllable through controlling the deposition amount of Fe3O4 nanoparticles on the capsules. (C) 2011 Elsevier Inc. All rights reserved.