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Surface-enhanced Raman scattering substrates based on nanometre scale structures on butterfly wings

Surface-enhanced Raman scattering (SERS) has received a great deal interest as an analytical tool due to its potential for obtaining Raman signals from single molecules. Many methods for preparing SERS-active substrate have been reported. These range from nano-particle based methods, which lack reproducibility, to highly reproducible nano-arrays requiring time consuming and costly preparation. We show that highly reproducible SERS can be achieved by applying a metallic coating to the brightly coloured regions of the graphium weiskei butterfly wing. Electron microscopy reveals the wing exhibit nanostructures with comparable dimensions to the roughness scale of SERS substrates. SERS measurements performed on wings coated with 60 nm of silver display enhancement factors of approximately 107 with no apparent background contribution from the wing. To demonstrate effectiveness and reproducibility the substrate is coated with a monoclonal antibody.