Our cloneable nanoparticle approach relies on a combination of NADPH-dependent metal(loid) reducing enzymes (e.g., GRLMR , mercuric reductase , etc.) combined with metal nanoparticle binding peptides . In this context, the elemental composition of the resulting nanoparticles is determined by the preferred enzymatic bio-coordination complex (i.e., substrate). Altering the substrate selectivity of a metal-reducing enzyme, therefore, can alter the elemental composition of a cloneable nanoparticle in which the enzyme is a component.