Filamentous virus decoration with gold nanoparticles: global fingerprints of bionanocomposites acquired with SERS

New construction blocks for nanomaterials have been found in nature itself: viruses. Synthetic methods to modify them are relevant for bionanomaterials design. In this paper, a method is presented that takes advantage of the natural functional groups in the fd virus structure to decorate them with gold nanoparticles. The method employs a bioconjugation reaction in which cysteine molecules are appropriately bonded, mediated by carbodiimides, to carboxyl and amine groups in the virus capsid proteins. fd virus with one gold nanoparticle at the tip end and gold nanowire-like structures were obtained. We can discriminate the different synthesized structures, using surface enhanced Raman spectroscopy in conjunction with principal component analysis. The general procedure developed here is a promising tool to determine how viruses are modified after a bioconjugation reaction.