Virus-material coupling

Viruses can be thought of as nucleoprotein-based supramolecular assemblies that have evolved into biological nanomachines capable of reproducing within cells and propagating throughout cells and organisms. A virus must be able to recognize specific cells, enter and navigate within them, and undergo the conformational rearrangements required for productive release of its genome. After replication of its macromolecular components in the host cell, the virion must be able to self-assemble, mature into a stable infectious entity, navigate back in and out of the cell, and withstand severe physical and chemical aggression in the extracellular environment. In response to so many selection pressures, the blind process of virus evolution has succeeded in selecting a remarkable set of features and many complex functions in relatively simple nucleoprotein structures. The recent advent of nanotechnology has led to a growing awareness of these possibilities, and to new approaches to the development of hybrid materials. Not all natural viruses and their capsids have the many properties and functionalities required, or at least they are not always optimized for the applications envisaged. Thus, many viral particles are chemically and/or genetically modified to enable their use in biomedicine, biotechnology or nanotechnology. In this lesson, we have focused on the synthesis of hybrid materials based on VMT (tobacco mosaic virus) or VMCD (cowpea chlorotic mottle virus). For example, the exterior and interior of VMT can be used to synthesize inorganic materials by electrolytic metal deposition. The inner surface of the VMT is negatively charged under physiological conditions, while the outer surface has a positive charge. The outside of the VMT can be functionalized with various minerals (cadmium sulfide, lead sulfide, iron oxide, silica, platinum, gold). As differential nucleation is electrostatically driven, as a result of the difference in surface charges, silver and copper can be incorporated inside the VMT's central channels. The encapsulation of inorganic compounds in VMT particles is also an active area of research. For example, the entrapment of luminescent lanthanide ions or fluorescent dyes and active ingredients in VMCDs opens up new avenues for the development of nanovectors. Mineralization reactions within VMCDs can also be driven electrostatically. The highly positively charged inner cavity provides an interface for the nucleation of anionic mineral species such as tungstates and vanadates. The same principle can be used to internalize titanium oxides or Prussian blue nanoparticles. In addition, the substitution of all basic residues on the N-terminus of the envelope protein with negatively charged glutamic acid enables favorable interactions with ferrous and ferric cations, whose condensation leads to the formation of magnetic iron oxides inside the capsid. External functionalization of the capsid with residues carrying thiol functions enables the formation of composites based on gold nanoparticles. These synthesis strategies, coupled or not with other physical processes(Atomic Layer Deposition [ALD], electrodeposition), have already led to the development of devices such as catalysts for hydrogen peroxide reduction, nanocomposite anodes with high capacities (2,300 ^mAhg-1 instead of 372 ^mAhg-1 for graphite), digital memories for nanoelectronics, VMT-polymer nanofibers for neuronal tissue repair.