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

Biotemplatedsyntheses have emerged as an efficient strategytocontrol the assembly of metal nanoparticles (NPs) and generate promisingplasmonic properties for sensing or biomedical applications. However,understanding the nucleation and growth mechanisms of metallic nanostructureson biotemplate is an essential prerequisite to developing well-controllednanotechnologies. Here, we used liquid cell Transmission ElectronMicroscopy (TEM) to reveal how the formation kinetics of gold NPsaffects their size and density on Tobacco Mosaic Virus (TMV). These in situ insights are used as a guideline to optimize bench-scalesynthesis with the possibility to homogenize the coverage and tunethe density of gold NPs on TMV. In line with in situ TEM observations, fluorescence spectroscopy confirms that the nucleationof NPs occurs on the virus capsid rather than in solution. The proximityof gold NPs on TMV allows shifting the plasmonic resonance of theassembly in the biological window.