The external surface of the plant virus Cowpea mosaic virus (CPMV) can be chemically modified with peptides that direct specific mineralization processes. Subsequent mineralization of the peptide-CPMV conjugates produces monodisperse nanoparticles of ca. 32 nm diameter coated with, for example, cobalt-platinum, iron-platinum or zinc sulfide, which cannot be readily prepared by other methods. This route is particularly attractive as it avoids the need to genetically engineer the protein surface of the virus to provide chimaeras for templated-mineralization. The synthetic procedure is environmentally friendly, as it proceeds at ambient temperature and pressure, in aqueous solvent. Further, the methodology is demonstrated to be generally applicable by the mineralization of a peptide-modified multiwalled carbon nanotube.