Abstract: The present invention provides a nanostructured substrate for SERS. A substrate of the invention comprises a surface featuring substantially monodisperse-sized metal nanoparticles disposed thereon. Preferably, the substrate surface provides for SERS and spectra therefrom. For example, a nanostructured substrate of the invention can be used to reproducibly and reliably detect or identify pathogens, molecules or combinations thereof. In one embodiment, a nanostructured substrate of the invention comprises a surface featuring metal nanoparticles substantially aggregated in clusters thereon. Exemplary metal nanoparticles disposed on the substrate surface can be silver, copper, gold or combinations thereof. Metal nanoparticles disposed on a substrate surface can also be substantially spheroidal comprising diameters in a range from about 40 to 120 nm.