Biomedical Engineering Reference
In-Depth Information
Fig. 30 Types of nanocarriers for drug delivery. (a) Polymeric nanoparticles: polymeric
nanoparticles in which drugs are conjugated to or encapsulated in polymers. (b) Polymeric
micelles: amphiphilic block copolymers that form nanosized core-shell structures in aqueous
solution. The hydrophobic core region serves as a reservoir for hydrophobic drugs, whereas
hydrophilic shell region stabilizes the hydrophobic core and renders the polymer water-soluble.
(c) Dendrimers: synthetic polymeric macromolecule of nanometer dimensions, which are com-
posed of multiple highly branched monomers that emerge radially from the central core.
(d) Liposomes: self-assembling structures composed of lipid bilayers in which an aqueous volume
is entirely enclosed by a membranous lipid bilayer. (e) Viral-based nanoparticles: in general, the
structure are the protein cages, which are multivalent, self-assembled structures. (f) Carbon
nanotubes: carbon cylinders composed of benzene rings. (Adapted from [ 107 ])
AlphaRx is one of the leaders in the development of nanoparticulate drug
delivery systems to enhance the bioavailability of the drugs towards targeted
diseased cells, promoting the required response while minimizing side effects.
A good illustration is given in Fig. 31 . Nanoscale drug platforms include a class
of particles made of FDA-approved polymers or lipids which, because of their size
and chemical composition, permit systemic and local treatment. Blood vessels that
supply tumors are more porous than normal vessels, making nanoscale drug
delivery systems a particularly attractive prospect.
External magnets are being used to guide a novel, intra-arterially administered
chemotherapy delivery vehicle directly to the tumor site (Fig. 32 ). Scott
C. Goodwin, chief of vascular and interventional radiology, UCLA Medical Center,
reported results of an ongoing phase I/II study of this new regional therapy
technique at the annual scientific meeting of the Society of Cardiovascular and
Interventional Radiology (http://www.cancernetwork.com/news/display/article/
10165/85758). The product, MTC-DOX (magnetic targeted carriers-doxorubicin),
currently being tested in primary liver cancer patients, is under development by
San Diego-based FeRx Incorporated. It consists of doxorubicin adsorbed to the
company's proprietary MTCs.
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