Biomedical Engineering Reference
In-Depth Information
perfluorinated compounds are also contrast agents for ultrasound imaging. The FDa
recently approved perflutren lipid microspheres (marketed as optison™), composed
of octafluoropropane encapsulated in an outer lipid shell and used for vascular
imaging by medical ultrasound [117]. however, pFC microspheres are fairly large
and have limited drug-targeting capacity. From an imaging point of view, pFC nano-
emulsions are very attractive for theranostic development since they allow easy
integration of multiple imaging modalities while at the same time they show
significant drug loading capacity and potential for controlled drug release.
Janjic
et al
. [118] reported in 2008 perfluoropolyether (pFpe) conjugates to several
fluorescent dyes. pFC nanoemulsions can also be labeled with nir dyes by entrapment
during nanoemulsification in the lipid or surfactant layer [3, 4, 119]. additionally, pFC
nanoemulsions designed as dual-mode imaging agents for optical and photoacoustic
imaging were reported by akers
et al
. [120]. pFC nanoemulsions were also investi-
gated as ultrasound imaging contrast agents in preclinical models [121].
as a theranostic platform, pFC nanoemulsions have attracted increasing interest
over the past 5 years. This is likely due to ease of preparation of pFC nanoemulsion
on a reasonable scale, their ability to support multiple imaging modalities without
added formulation complexity, and diverse drug loading options (entrapment, conju-
gation) with controlled release. Figure 15.5 shows pFC molecules used for theranos-
tic nanoemulsion development to date. recently, Janjic
et al
. reported theranostic
nanoemulsions carrying a nonsteroidal anti-inflammatory drug (nsaiD) [3, 4]. The
lipophilic drug celecoxib was incorporated into the hydrocarbon core of the triphasic
FC/hC/W nanoemulsion during processing. The nanoemulsion, once loaded into
cells, provided
19
F Mr signal, nir signal, and suppressed CoX-2-driven pge2
release by releasing the drug in the cytoplasm.
Wickline
et al
. developed unique pFC nanoemulsions designed to deliver biologic
cytolytic peptides specifically to tumors [122]. They named these particles “nanobees.”
This pioneering work laid out a foundation for pFC nanoemulsion theranostic
development and also put these agents at the forefront of drug delivery vehicle design.
Cytolytic peptides were identified as highly attractive and effective anticancer agents.
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Br
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n
Peruoropolyether
F
O
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O
Peruorooctylbromide
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Peruoro-15-Crown-5 Ether
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Peruoropentane
Peruorodecaline
figure 15.5
perfluorocarbons used for theranostic nanoemulsions and nanoparticle
development.
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