Notes:

We would like to thank Prof. J. J. Vlassak and H. Li for the use of the four-point flexure apparatus and Prof. G. M. Whitesides and Dr. M. Reches for access to their equipment during the construction of J.A.’s laboratory. We thank Dr. A. Taylor for the fabrication of Si nanostructures. B.P. would like to extend his gratitude to the Fulbright Visiting Scholar Program for financial support. This work was partially supported by the Materials Research Science and Engineering Center (MRSEC) of the National Science Foundation under NSF Award Number DMR-0213805. Supporting Information is available online from Wiley InterScience or from the author. This article is part of a special issue on Biomaterials.