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Q. Lv et al.
activity of PSMA, resulting in reduced cancer cells migration/invasion [136]. In
another study, researchers used a derivative of indocyanine green (MPA) as NIR
dye (Ex~780 nm, Em~810 nm) for anti-MUC1 DNA aptamers labeling. The in vivo
imaging performances of the probe (APT-MPA) were compared with the dye only
(MPA) and the polyethylene glycol-modified probe (APT-PEG-MPA). Strong tumorspecific fluorescence was observed for the APT-MPA and APT-PEG-MPA groups,
except the MPA control group. The PEG-modified probe (APT-PEG-MPA) exhibited
much quicker clearance comparing to that of APT-MPA in the biodistribution assay
[137].
Luminescent nanomaterials have exhibited as excellent imaging materials for
cancer research in various models, for their several great advantages as high fluorescence, low photobleaching, and chemical stability. Quantum dots (QDs) are one kind
of the most commonly used fluorescence imaging nanomaterials. For example, the
fluorescence QDs have been conjugated with mucin 1 (MUC1)-targeting aptamers
and variant of epidermal growth factor receptor (EGFRvIII)-targeting aptamers via
chemical bonds for in vivo imaging. The anti-MUC1 aptamer-QDs probe can identify the MUC1 overexpressing A549 cancer cells in subcutaneously xenografted
nude mice and shows strong fluorescence in the tumor tissue only [138] (Fig. 9.9a).
EGFRvIII expresses only on cancer cells, and participates in cancer cells proliferation, invasion, and resistance to therapy strategy [139], which makes it a critical target
for cancer imaging and therapy. The anti-EGFRvIII aptamers (A32) were chemically
conjugated with streptavidin-PEG-CdSe/ZnS QDs to form a cancer cells-targeting
probe (QD-A32 Apt) for U87-EGFRvIII overexpressing cells imaging orthotopically
in nude mice [140]. Six hours after tail-vein injection, strong fluorescence signals
can be observed only in U87-EGFRvIII overexpressing cells in tumor areas, except
U87 tumors.
9.6.2 Magnetic Resonance Imaging (MRI)
Using aptamers as specific targeting elements, the classic imaging technique as MRI
has been introduced for high-quality visualization of internal soft tissue morphology
and organ structures. For example, the anti-αvβ3 aptamers (Apt αvβ3) were immobilized onto magnetic nanoparticles (MNPs) for cancer cells-specific observation
using MRI strategy. The Apt αvβ3-MNPs accumulate in the tumor region and produce
enhanced MR signals at 24 h post-injection in the tumor mice model [141] (Fig. 9.9b).
In another study, the MRI probe consisted of anti-hypoxia-inducible factor-1α (HIF1α) aptamer and PEG-modified manganese magnetic nanoparticles. This Apt-PEGmodified Fe 3 O 4 @Mn (D-Fe 3 O 4 @PMn) probe offers significantly higher MRI signal
intensity for cancer cells in T1-weighted MR imaging in mice model, and shows
acceptable biocompatibility [142].
Q. Lv et al.
activity of PSMA, resulting in reduced cancer cells migration/invasion [136]. In
another study, researchers used a derivative of indocyanine green (MPA) as NIR
dye (Ex~780 nm, Em~810 nm) for anti-MUC1 DNA aptamers labeling. The in vivo
imaging performances of the probe (APT-MPA) were compared with the dye only
(MPA) and the polyethylene glycol-modified probe (APT-PEG-MPA). Strong tumorspecific fluorescence was observed for the APT-MPA and APT-PEG-MPA groups,
except the MPA control group. The PEG-modified probe (APT-PEG-MPA) exhibited
much quicker clearance comparing to that of APT-MPA in the biodistribution assay
[137].
Luminescent nanomaterials have exhibited as excellent imaging materials for
cancer research in various models, for their several great advantages as high fluorescence, low photobleaching, and chemical stability. Quantum dots (QDs) are one kind
of the most commonly used fluorescence imaging nanomaterials. For example, the
fluorescence QDs have been conjugated with mucin 1 (MUC1)-targeting aptamers
and variant of epidermal growth factor receptor (EGFRvIII)-targeting aptamers via
chemical bonds for in vivo imaging. The anti-MUC1 aptamer-QDs probe can identify the MUC1 overexpressing A549 cancer cells in subcutaneously xenografted
nude mice and shows strong fluorescence in the tumor tissue only [138] (Fig. 9.9a).
EGFRvIII expresses only on cancer cells, and participates in cancer cells proliferation, invasion, and resistance to therapy strategy [139], which makes it a critical target
for cancer imaging and therapy. The anti-EGFRvIII aptamers (A32) were chemically
conjugated with streptavidin-PEG-CdSe/ZnS QDs to form a cancer cells-targeting
probe (QD-A32 Apt) for U87-EGFRvIII overexpressing cells imaging orthotopically
in nude mice [140]. Six hours after tail-vein injection, strong fluorescence signals
can be observed only in U87-EGFRvIII overexpressing cells in tumor areas, except
U87 tumors.
9.6.2 Magnetic Resonance Imaging (MRI)
Using aptamers as specific targeting elements, the classic imaging technique as MRI
has been introduced for high-quality visualization of internal soft tissue morphology
and organ structures. For example, the anti-αvβ3 aptamers (Apt αvβ3) were immobilized onto magnetic nanoparticles (MNPs) for cancer cells-specific observation
using MRI strategy. The Apt αvβ3-MNPs accumulate in the tumor region and produce
enhanced MR signals at 24 h post-injection in the tumor mice model [141] (Fig. 9.9b).
In another study, the MRI probe consisted of anti-hypoxia-inducible factor-1α (HIF1α) aptamer and PEG-modified manganese magnetic nanoparticles. This Apt-PEGmodified Fe 3 O 4 @Mn (D-Fe 3 O 4 @PMn) probe offers significantly higher MRI signal
intensity for cancer cells in T1-weighted MR imaging in mice model, and shows
acceptable biocompatibility [142].