**5. Patents**

This work has been submitted with a preliminary patent and invention disclosure.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1996-1944/12/6/894/s1, Figure S1: Silk hydrogels equilibrated in 100 mM Na2PdCl4 and 100 mM K2PtCl6 reduced in 2 M NaBH4; Figure S2: Silk hydrogels equilibrated in 100 mM HAuCl4 reduced with 2 M DMAB; Figure S3: SEM images of the HFIP–silk noble metal fibers; Figure S4: SEM images of the HFIP–silk aerogels for silk–palladium, silk–platinum, and silk–gold; Figure S5: X-ray diffraction (XRD) and Fourier transform infrared (FTIR) absorption spectra for the silk–gold composite aerogels, Figure S6: TGA curves of the silk–gold aerogels; Figure S7: Nitrogen gas adsorption–desorption curves for the silk–gold aerogels.

**Author Contributions:** Conceptualization, A.N.M. and F.J.B.; Data curation, A.N.M., F.J.B. and C.K.N.; Formal analysis, A.N.M. and F.J.B.; Funding acquisition, A.N.M. and F.J.B.; Investigation, A.N.M., F.J.B., C.K.N., M.Y.R., J.W. and R.K.S.; Methodology, A.N.M. and F.J.B.; Project administration, A.N.M. and F.J.B.; Resources, A.N.M., F.J.B. and J.K.W.; Supervision, A.N.M. and F.J.B.; Validation, F.J.B.; Original draft preparation, A.N.M. and F.J.B.; Review and editing of manuscript, A.N.M., F.J.B., C.K.N., E.A.N., M.Y.R., J.W., R.K.S., K.W. and J.K.W.

**Funding:** This work was funded by a Faculty Development Research Fund gran<sup>t</sup> from the United States Military Academy. A.N.M. received partial funding from the National Academy of Sciences through the National Research Council Davies Fellowship and through the Army Research Office (ARO).

**Acknowledgments:** The authors acknowledge Stephen Bartolucci at Watervliet Arsenal and Benet Laboratories for providing use of their SEM. The authors also acknowledge David Kaplan from Tufts University for the raw silk cocoons.

**Conflicts of Interest:** The authors declare no conflicts of interest.
