Hyeon’s team developed its wrap-bake-peel process to transform nanostructured materials. Although thermal treatment is routinely used to induce such transformations, and to improve material properties, high-temperature annealing usually destroys the properties of nanomaterials because the materials aggregate and sinter. The new method overcomes this problem because the materials are protected during the wrap stage.
The technique involves three steps: coating the akagenite (beta-FeOOH) with silica, heating the materials to up to 500 °C and then peeling off the silica layer. Hyeon told nanotechweb.org that the method could be used on a wide variety of nanocompounds, not just akagenite, to produce useful nanomaterials. What is more, the technique could easily lend itself to large-scale production of biocompatible nanoparticles.
The iron oxide nanocapsules produced in this simple process could find use in drug delivery because they are hollow, biocompatible and can be dispersed in water. They could also be used as MRI contrast agents. "In other words, in simultaneous diagnosis and therapy," explained Hyeon.
The researchers are now testing their as-prepared iron oxide capsules on animals.
The work was reported in Nature Materials.