Using proteins from a common tobacco plant virus, McGill chemistry researchers have developed a simple, eco-friendly way to arrange gold nanoparticles into ultrathin sheets, strengthening the particles' optical properties. The result: cheaper, safer materials for solar panels, sensors and advanced optical devices.
Gold nanoparticles are only effective in strengthening optical signals when the nanoparticles are arranged on a surface and spaced at exact distances.
Until now, creating those patterns required harsh chemicals and tightly controlled lab conditions. The McGill team's breakthrough was to modify a tobacco mosaic virus so that it would self-assemble into sheets in water at room temperature, with the nanoparticles properly spaced.
"If you just chuck these nanoparticles on a surface, some fraction of them will randomly cause enhancement," said Associate Professor and co-author Amy Blum. "But if you can get them to be at a fixed good distance, then the whole surface is active."
The result is a nanomaterial that can be made at a lower cost and with less environmental impact, compared to the existing method.
Nature's building blocks
Blum said that this work represents an important step toward sustainable nanomaterials for everyday technologies.
"This is about using nature's building blocks to make technology cleaner, cheaper and smarter," the researcher said.
"For safety, we don't use the active virus. We just use the shell, which contains no genetic material," she added.
Building the protein scaffold
To build the scaffold, the team modified the virus's protein by adding a short chain of histidine - essentially tiny hooks that latch onto gold nanoparticles and guide the proteins to self-assemble into ultrathin sheets.
"We rely on a large number of very weak interactions," Blum said. "If I have one, it definitely won't hold together. If I have 15, it'll hold it very, very rigidly."
Without this modification, the protein tends to clump. The weaker interactions instead encourage the proteins to lay flat, Blum noted.
The team was surprised to find that under certain conditions the sheets could roll themselves into nanoscale tubes. This opens the way for researchers to investigate whether the tubes might one day function like nanoscopic fibre-optic cables, Blum said.
About this study
"Extended Plasmonic Nanostructures Templated by Tobacco Mosaic Virus Coat Protein," by Ismael Abu-Baker, Alexander Al-Feghali, Elliot Zolfaghar, Gangamallaiah Velpula, Artur P. Biela, Steven De Feyter, Jonathan G. Heddle, Gonzalo Cosa and Amy Szuchmacher Blum, was published in Small in October 2025.
