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Fig. 15 Comparative tumor uptake and fluorescence-imaging potential of a cyanine dye
(CD-COOH) and the corresponding CD-PAA NP conjugate. The cyanine dye was conjugated at
the periphery of the nanoparticles (NPs) (BALB/c mice bearing Colon26 tumors at 24 h
postinjection, dose of the CD: 0.3
μ
mol/kg)
unpublished results). The free and post-loaded CD-COOH was removed by spin-
filter (100 KD) with a continuous wash with ethanol. The release of the CD-COOH
was confirmed by measuring the absorption spectra of the filtrates (ethanol wash).
The concentration of the CD in nanoparticles was calculated by subtracting the
amount recovered in ethanol washes from the total amount used for conjugating
to NPs.
The tumor avidity of the free CD-COOH and the corresponding CD-PAANPs
conjugate was compared in BALB/c mice bearing Colon26 tumors at similar
parameters (dose: 0.3
mol/kg). The mice were imaged at variable time points
using the IVIS spectrum (PerkinElmer) by exciting the dye at its longest wave-
length absorption. The results summarized in Fig.
15
indicate that the cyanine dye
(CD-COOH) alone had limited tumor avidity (1-72 h, only 24 h data is shown),
whereas the corresponding NPs showed significant tumor-imaging potential.
More recently, Wang et al. and Gupta et al. [
78
,
79
] conducted a series of studies
designing a multifunctional PAA NP which incorporated 3-(1
0
-hexyloxy)ethyl-3-
devinyl pyropheophorbide-alpha (HPPH), a PS with far greater tumor-targeting
efficiency, excellent PDT efficacy, and a longer excitation wavelength; addition-
ally, an NIR CD fluorescence imaging agent was also incorporated (Fig.
16
). In the
first study, Wang et al. demonstrated that among the NPs synthesized using
covalent conjugation, encapsulation, and post-loading (loading of agents into the
porous nanoparticle post
μ
its synthesis) approach. The post-loaded PAA NP
