Peptide-coated CdS quantum dots for the optical detection of copper(ii) and silver(i)Electronic Supplementary Information (ESI) available: experimental procedures for peptide synthesis and optical spectra measurements. See http://www.rsc.org/suppdata/cc/b3/b308991f/We thank Dr Matthew J. Lynn and Dr Bret J. Elkind at the University of Miami Center for Advance Microscopy for their help with TEM imaging and critical reading of manuscript. This work is supported by the National Science Foundation, CHE-0091390.