Biomolecular Self-Assembly of Nanorings on a Viral Protein Template

Although there have been many advances in synthesizing nanoparticles, their assembly into deterministic and controllable patterns remains a major challenge. Biological systems operate at the nanoscale, building structural components with great chemical specificity that enable the processes of life. By adapting them to our needs, it is possible to utilize well-defined and well-controlled scaffolds to produce materials with novel properties resulting from precise ordering on the nanoscale. This approach uses spatial arrangement instead of nanoparticle size, shape, or composition to control material properties through the collective interactions between neighboring nanoparticles. Here, we demonstrate the use of tobacco mosaic virus (TMV) coat protein as a template to self-assemble plasmonic nanoparticles. Surface plasmons are resonant oscillations in the free electrons of a metal that are excited through interaction with light. These plasmonic oscillations can couple together, giving rise to more complex modes like plasmonic ring resonances that can be used to tune the response to incident light. By exploiting the self-assembling properties and chemical addressability of TMV coat protein, we can utilize site-directed mutagenesis and bioconjugation strategies to produce highly symmetrical plasmonic nanorings, as evidenced by transmission electron microscopy (TEM). Thus, we show the utility of viral proteins in designing and assembling nanostructured building blocks for advanced materials.