Recently our group has been focused on medical applications of various uniform-sized nanoparticles. For example, using 3 nm-sized iron oxide nanoparticles, new non-toxic MRI contrast agent was realized for high resolution MRI of blood vessels down to 0.2 mm, which can be potentially applied to early diagnosis of cancers, stroke, and cardiovascular diseases. We demonstrated that ceria nanoparticles could protect against ischemic stroke in an in vivo animal model. In animal trials, intravenously administered ceria nanoparticles considerably reduced the stroke volume and nerve damage. We reported the first successful demonstration of high-resolution in vivo three-photon imaging using biocompatible and bright Mn2+ doped ZnS nanocrystals. Tumor vascular lining could be visualized with a resolution as small as 2 micrometer, which can be eventually applied to real-time monitoring of tumors during cancer surgery.
We reported the large-scale synthesis of magnetite nanocrystals imbedded in a carbon matrix and hollow iron oxide nanoparticles. These iron oxide-based nanomaterials exhibited very high specific capacity and good cyclability. We demonstrate galvanic replacement reactions in metal oxide nanocrystals. When Mn3O4 nanocrystals were reacted with iron(II) perchlorate, hollow box-shaped nanocrystals of Mn3O4/γ-Fe2O3 (“nanoboxes”) were produced. Because of their non-equilibrium compositions and hollow structures, these nanoboxes exhibited good performance as anode materials for lithium ion batteries.