Playing “Nano -Lego ”: VNPs as Building Blocks for the Construction of Multi -Dimensional Arrays - Viral Nanoparticles: Tools for Materials Science and Biomedicine - page 172

This polymerization stabilizes and fixes the head-to-tail structures

formed. Fibers only about 20 nm in width but with lengths up 10

in situ

m can
be fabricated using this method (Fig. 7.3b). By varying the pH, bundles of
such aligned head-to-tail TMV assemblies can also be fabricated. At neutral
pH, aniline prevents lateral organization of TMV and thin fibers consisting
of single TMV particles aligned head to tail are assembled. At lower pH, the
assembly of bundles is preferred (Fig. 7.3c,d). The formation of bundles can
be explained by hydrophobic interactions between the polyaniline at low pH,
which promotes parallel alignment of TMV assemblies (Niu

µ

et al ., 2007a.,b;

Wang ., 2007).

Bundles of the phage M13 have also been fabricated. M13 particles
expressing a peptide specific for Co

et al

ions as pVIII (main coat protein)

2+

fusion were utilized for Co -induced assembly into phage bundles. CoPt

nanoparticles were subsequently synthesized, and a metallic network of
phage bundles was created (Lee

2+

et al ., 2006).

Figure 7.2 Transmission electron microscopy (TEM) image of TMV after Pd(II)

activation, followed by electroless deposition of nickel. Two adjacent virion
aggregates: the right aggregate comprises three TMV particles in which nickel
nanowires were grown. The nickel nanowires are continuous and approximately
600 nm in length. Energy-resolved scanning TEM images proved that the dark wire
is indeed composed of nickel. Inset: a single virion is filled with a 200-nm-long wire
with a diameter of approximately 3 nm. Reproduced with permission from Knez, M.,
Bittner, A. M., Boes, F., Wege, C., Jeske, H., Maiß, E., and Kern, K. (2003) Biotemplate
synthesis of 3-nm nickel and cobalt nanowires, Nano Lett. , 3 (8), 1079-1082.