X. Shi and S. H. Wang contributed equally to this work. This project has been funded in whole or in part by the National Institutes of Health (NIH) (under the contract # NIH 1 RO1 EB002657, NOI-CO-97111, and NIH 1 RO1 CA119409) and the Michigan Economic Development Corporation-Life Sciences Corridor Fund (under award GR-472). The authors thank Sasha Meshinchi for his assistance with the TEM experiments and valuable discussions. Supporting Information is available online from Wiley InterScience or from the author.