A method based on a double emulsion system (solid-in-water-in-oil-in-water) has been developed for the production of nanoparticles-in-microparticles (NIMs). The distribution of nanoparticles within the NIMs was explored using light and electron microscopy and through assessment of drug loading and release profiles. The extent of nanoparticle entrapment within the NIMs was found to be dependent on the state (wet vs. dry) in which the nanoparticles were introduced to the formulation. The technique was readily adaptable to produce NIMs of different morphologies. It is proposed that NIMs and this method to produce them have broad application in drug delivery research.
