Iron Oxide Nanoparticles and Derivatives for Biomedical Imaging and Application in Cancer Diagnosis and Therapy - Bioanalysis Advanced Materials Methods and Devices - page 3

Fig. 1.1 Superparamagnetic iron oxide nanoparticles coated with dextran serve as templates for
conjugation of several molecular moieties. In this example, magnetic nanoparticles are conjugated
to a tumor targeting peptide, NIR fluorescent dye (cy5.5), and siRNA
precursor is a clinically approved contrast agent [ 14 ]. The iron oxide nanoparticles
discussed in this chapter have a ~5 nm superparamagnetic iron oxide core. They are
coated with dextran, which is a biodegradable and biocompatible polymer.
The dextran surface is further cross-linked using several chemical processes to
introduce amine groups for functionalization. Multiple moieties including targeting
peptides [ 17 ], aptamers [ 33 , 34 ], NIR fluorescent dyes [ 26 ], therapeutic materials
[ 31 ], etc. can be conjugated to iron oxide nanoparticles through amine terminals
and bifunctional linkers, Fig. 1.1 .
1.3 Multifunctional Cancer Imaging with Iron Oxide
Nanoparticles
Cancer diagnosis by nanotechnology is an emerging field. Detecting cancer nonin-
vasively (a feature of nanotechnology) benefits the patient in obvious and
subtle ways. Alternatively, surgical methods may produce high morbidity and are
completely unnecessary for the patient who does not have the disease. Noninvasive
imaging of cancer with high sensitivity is crucial and achievable, as an inherent
property of magnetic nanoparticles. Moreover, a slight modification of the nano-
particle to include a therapeutic moiety offers the possibility of combining diagno-
sis with an initial drug delivery step.
There are two main approaches in imaging the disease with magnetic
nanoparticles. The first is passive-targeted imaging in which the nanoparticles
reach the malignant tissues due to the mechanical properties of the nanoparticles,
their size, and the physical properties of the surface coating such as charge and
hydrophobicity [ 24 ]. The second, active-targeted imaging approach, incorporates
a targeting moiety into the nanoparticle, which facilitates cellular uptake by
malignant cells [ 29 ].