VNPs as Tools for Nanomedicine - Viral Nanoparticles: Tools for Materials Science and Biomedicine - page 216

. VnPs AS SenSorS For BIoMedICAl IMAgIng

Various imaging techniques have been developed for non-invasive in vivo

imaging, such as computed tomography (CT), magnetic resonance imaging
(MRI, see Section 8.3.2), positron emission tomography (PET), as well as
optical imaging (Section 8.3.1) (reviewed in Cai & Chen, 2007; Graves .,

2004; Rudin & Weissleder, 2003). Early detection, treatment, and monitoring
of disease have great potential to improve patient outcomes. Furthermore,
development and improvement of imaging modalities and techniques play
a key role in biomedical research. The development of ligands for tumor-
specific markers as well as vascular homing peptides (Arap

et al

et al ., 2002;

Hajitou ., 2006a; Nanda & St. Croix, 2004; Ruoslahti, 2002) has opened

the door for creating novel targeted imaging devices with higher specificity
for desired locations and reduced background in the surrounding tissues.
VNPs and other nanomaterials can be utilized to interlink targeting and
imaging modalities. VNPs have been combined with organic fluorophores,
QDs, metallic nanoparticles, and gadolinium (Gd) complexes (reviewed
in Manchester & Steinmetz, 2008; Singh

et al

et al ., 2006b; Steinmetz & Evans,

2007; Steinmetz ., 2008). These hybrid VNPs can be

fabricated using a broad range of design principles, including bioconjugation
(Chapter 4), encapsulation, and infusion (Chapter 5), or by making use of
biomineralization techniques (Chapter 6).
Hybrid VNPs can be categorized into three main groups:
Fluorescent VNP hybrids: These are VNPs covalently modified with
organic biodegradable dyes for applications in fluorescence optical imaging.
The feasibility of intravital vascular imaging using fluorescent dye-labeled
CPMV probes has been demonstrated (see Section 8.3.1).
Lanthanide-VNP complexes: These are VNPs displaying lanthanides,
such as Gd

et al ., 2009b; Young et al

. Applications of such complexes are envisioned in the
field of MRI imaging (see Section 8.3.2).
VNP-inorganic nanoparticle complexes: These are VNPs decorated
with or encapsulating inorganic nanoparticles. Mineralized or metalized
structures also fall into this category. VNPs with metal or QD cores
can be regarded as plasmonic composite materials with potentially
interesting biosensing applications. These materials can be activated
using a light source; plasmons (i.e., density waves of electrons) are
generated upon activation that can be detected using various spectroscopy
methods (Section 8.3.3).

3+

or Tb

3+

..1 Fluorescent-labeled VnPs for Intravital Vascular Imaging

The feasibility of fluorescent-labeled CPMV particles for intravital
vascular imaging in live mouse embryos has been demonstrated (Fig. 8.4)