It's been a while since we enjoyed a nano breakthrough. But recently, May 24th to be exact, Prof. Taeghwan Hyeon (Oh et al., Science, 340, 964) and his group at Seoul National University took the galvanic exchange method of making nanocages (e.g. see Prof. Younan Xia's seminal work on gold nanocages) and applied to metal oxides. They successfully made boxes of iron oxides by mixing Fe3+ with Mn3O4 nanocubes. This is a major expansion of the galvanic exchange methodology and certainly we'll see a trillion other examples, since metal oxides are much more abundant and stable than metallic counterparts (in case you forget, just think about our oxygen rich atmosphere). Congrats to Hyeon and Nicola Pinna (a WCU prof. at SNU) for another spectacular discovery!