Encapsulating Materials within VNPs - Viral Nanoparticles: Tools for Materials Science and Biomedicine - page 136

The ability to produce particles of distinct sizes makes VNPs valuable
building blocks for nanotechnology. Understanding the self-assembly process
of VNPs and VLPs is an important goal. Knowledge about the principles of
the self-assembly process and an understanding of the factors that govern
assembly of particles of a distinct size and symmetry are expected to broaden
the applications, versatilities, and possibilities. Using the BMV coat proteins
and nanoparticle cores of different sizes, it has been shown that the size of
the VLP is governed by the size of the nanoparticle core (Sun

., 2007).
In a more recent study, the relation between changes in the coat protein,
such as deletions, and

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self-assembly around nanoparticles cores
has been studied using coat proteins of CCMV. Hybrid nanoparticle-
containing VLPs could be assembled even when large portions of the N-
terminus of the coat protein (in the native VNP, the N-terminus binds to
the nucleic acid and thus plays a critical role in assembly of particles)
were deleted (Aniagyei

in vitro

et al ., 2009). This again underlines the flexibility of

the system.

..1.. From structural studies to applicaions

The potential of nanoparticle-containing VLPs bridges the fields of
materials and medicine. The materials properties of gold-core-containing
VLP crystals were evaluated for potential application as high-performance
metamaterials. A metamaterial is a synthetic material that gains its
functional properties, such as optical and electronic properties, from its
structure rather than from its composition. The 3D structure of crystalline
films of gold-core-containing VLPs has a lattice constant of 28 nm (for VLPs
with 12 nm-sized gold cores), and thus might be a good candidate material
for optoelectronics. Optical spectroscopy indicated a difference between the
optical transmission spectrum of a VLP crystal and that of a dilute solution
of VLPs (Fig. 5.10). A double-spectral feature was observed indicating the
signature of multipolar coupling between adjacent gold cores leading to
plasmonic band formation. The spectrum of the VLP crystal shows two
absorption bands, one shifted to the blue and the other one to the red of
the surface plasmon peak of the single VLP (Fig. 5.10). Such plasmonic band
splittings in metallodielectric materials have been predicted theoretically;
however, this has been one of the few examples where it has been shown
experimentally (Sun ., 2007). The surface lattice of the VLP crystal can

be varied using different-sized gold nanoparticles as cores. These features
suggest that the gold-core-containing VLP crystals are attractive candidates
for the development of metamaterials with potential applications in sensors
and data storage.

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