CHAPTER 9: Virus-based systems for functional materials

Virus-based bionanotechnology holds the promise of control over the structure, properties and functionality of materials at the nanometre scale. After all, viruses, and by extension virus-like particles (VLPs), represent some of the largest hierarchical protein constructs found in Nature. Their symmetrical architecture and their high degree of monodispersity, compared with other nanoparticles, make them unique as nanobuilding blocks. Furthermore, many of these particles seem to have specific and tuneable physical properties that can be utilized for their further function and manipulation. Viruses and VLPs are therefore highly desirable nanobuilding blocks that could find applications ranging from nanocontainers, for studying reactions in confinement or drug delivery, to modular structural components, that allow for the creation of complex nanoarchitectures, and eventually functional materials. This chapter is intended to generate an understanding of how the structure, modification and organization of viruses enable them to be the key component in these potential, functional materials, a field recently introduced as chemical virology. Ultimately, these functional virus-based materials could allow the construction of novel optical, electronic, catalytic, imaging and other nano-scale precision-based applications

Protein Cages as Containers for Gold Nanoparticles

Abundant and highly diverse, viruses offer new scaffolds in nanotechnology for the encapsulation, organization, or even synthesis of novel materials. In this work the coat protein of the cowpea chlorotic mottle virus (CCMV) is used to encapsulate gold nanoparticles with different sizes and stabilizing ligands yielding stable particles in buffered solutions at neutral pH. The sizes of the virus-like particles correspond to <i>T</i> = 1, 2, and 3 Caspar–Klug icosahedral triangulation numbers. We developed a simple one-step process enabling the encapsulation of commercially available gold nanoparticles without prior modification with up to 97% efficiency. The encapsulation efficiency is further increased using bis-p-(sufonatophenyl)­phenyl phosphine surfactants up to 99%. Our work provides a simplified procedure for the preparation of metallic particles stabilized in CCMV protein cages. The presented results are expected to enable the preparation of a variety of similar virus-based colloids for current focus areas