Preparation of high quality nanowires by tobacco mosaic virus templating of gold nanoparticles

A protocol for the preparation of stable suspensions of well-defined metallized tobacco mosaic virus (TMV) nanorods in high yields and with uniform coatings is reported. Inorganic growth on the virion surface was controlled by adding aliquots of gold precursor (HAuCl4) and reducing agent (NaBH4) incrementally over five addition-reduction cycles to produce hybrid anisotropic nanostructures consisting of densely packed gold nanoparticles. Several novel steps, including addition of ethanol after the first addition-reduction cycle and wrapping of the TMV/Au nanohybrids with poly-L-lysine, were introduced into the protocol to ensure high homogeneity and stability in the nanowire suspension. Control of the interparticle spacing in the metallized nanostructures was achieved by restricting the number of reaction cycles used to less than four iterations. The importance of bio-mediated reduction was probed using laser light scattering microscopy. The results indicated that short incubation times were consistent with increased nanoparticle monodispersity and high fidelity replication.