In Situ Insights into the Nucleation and Growth Mechanisms of Gold Nanoparticles on Tobacco Mosaic Virus.

Biotemplated syntheses have emerged as an efficient strategy to control the assembly of metal nanoparticles (NPs) and generate promising plasmonic properties for sensing or biomedical applications. However, understanding the nucleation and growth mechanisms of metallic nanostructures on biotemplate is an essential prerequisite to developing well-controlled nanotechnologies. Here, we used liquid cell Transmission Electron Microscopy (TEM) to reveal how the formation kinetics of gold NPs affects their size and density on Tobacco Mosaic Virus (TMV). These in situ insights are used as a guideline to optimize bench-scale synthesis with the possibility to homogenize the coverage and tune the density of gold NPs on TMV. In line with in situ TEM observations, fluorescence spectroscopy confirms that the nucleation of NPs occurs on the virus capsid rather than in solution. The proximity of gold NPs on TMV allows shifting the plasmonic resonance of the assembly in the biological window.