Biomedical Engineering Reference
In-Depth Information
Core-Shell
Nanoparticle
Nanocrystal
Nanoemulsion
Micelle
Lipid-Polymer Hybrid
Nanoparticle
Liposome
Filomicelle
FIGuRE 4.1
Examples of nanocarriers for drug delivery or medical imaging. By tuning the physiochemi-
cal properties and conjugating the particles with targeting ligands, site-specific delivery can
be achieved. Particles can also be loaded with drugs or imaging agents to deliver a payload at
the target site.
206, 207]. Also, combinatorial methods employing nanoparticles loaded with
anti-cancer therapeutics and pro-apoptotic inhibitors have been investigated.
Devalapally [197] loaded poly(caprolactone)-poly(ethylene glycol) (PCL-PEG)
micelles with paclitaxel and C6-ceramide, a pro-apoptotic signaling messen-
ger. In another study, nanoemulsions approximately 140 nm in diameter have
also been developed which, when loaded simultaneously with paclitaxel and
the pro-apoptotic MDR modifier curcumin, effectively inhibited multidrug-
resistant SK-OV-3 ovarian adenocarcinoma cells [208].
The intracellular delivery of therapeutic agents may be most beneficial
when directed towards specific cytoplasmic components or organelles, such
as endosomes, lysosomes, mitochondria, or the nucleus (Figure 4.2) [209].
Thus, nanocarriers will require engineering in order to cross the plasma
membrane and release their payload within organelles or in the cytoplasm.
Partitioning across the cellular membrane is a described mechanism used
for vesicular and positively charged dendrimeric vesicles to enter cells, thus
passage into cells is governed mostly by receptor-mediated endocytosis
[210]. Likewise, receptor ligands, such as folic acid and transferrin, can be
employed to initiate receptor-mediated endocytosis [209], but endosomal/
lysosomal escape is often necessary in order to avoid enzymatic degrada-
tion of the therapeutic agent. Intelligent carriers are engineered to escape
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