The goal was to prepare composite lipid/Fe3O4/SiO2 mesoparticles from hollow porous silica shell particles (500-600 nm) prepared by emulsion method, superparamagnetic iron oxide nanoparticles (5-20 nm) prepared by co-precipitation method and lipid nanoparticles (30-40 nm) prepared by phase inversion temperature method. First, composite Fe3O4/SiO2 particles were prepared by coating the silica shell by a layer of iron oxide. The composite particles were then loaded by the active substance and coated by a layer of lipid nanoparticles to form a barrier which blocks diffusion in and out of the particles, thus preserving the active substance inside. The particles were characterised using transmission electron microscopy, dynamic light scattering and electrophoretic light scattering.
The release mechanism is triggered by alternating magnetic field in the radiofrequency range, which heats up the magnetic iron oxide particles and melts the lipidic barrier. Pores are no longer blocked and the active substance diffuses into the environment. Release kinetics of the active substance were measured using UV-VIS spectrophotometry. The ability of the particles to be visualised by Magnetic Resonance Imgaging (MRI) was demonstrated.
