The Effects of Magnetic Nanoparticles Incorporated in Polyelectrolyte Capsules

Polyelectrolyte multilayer capsules are synthesized comprising of 12 total layers each containing a single layer of iron oxide nanoparticles in shells 4, 6, 8 or 10. A protein-labelled dye is embedded in the calcium carbonate template core as a model for the encapsulation of a drug. The core is dissolved after 6 layers are formed. Two types of magnetic nanoparticles are incorporated into various capsule shells: ferric oxide (Fe2O3, 50 nm) and iron oxide (Fe3O4, 15 nm), a 1:1 (vol.) mixture of the two types of nanoparticles suspensions is also used. Nanoparticle inclusion reduces the capsule sizes in all cases with the order of effect Fe3O4 [ Fe2O3 [ Fe2O3/Fe3O4 mixture. When Fe3O4 or a Fe2O3/Fe3O4 mixture is incorporated in layer 6 the reduction in size of the final capsules is less than expected. The number of surviving capsules containing nanoparticles are lower than control regardless of which of the nanoparticles is used but here the effect of Fe3O4 or a mixture of the two types of nanoparticles incorporated in layer 6 was slightly out of step. The amount of iron incorporated is almost the same regardless of which shell the nanoparticles were incorporated but the iron content using 50 nm nanoparticles is generally slightly higher than that obtained with 15 nm nanoparticles.