Biomedical Engineering Reference
In-Depth Information
and polymers such as PVA and dextran [60]. Numerous studies are in progress in which tumors are
targeted
in vivo
for therapeutic applications such as drug delivery and hyperthermic destruction
of tumors. The fi rst clinical magnetic drug trials targeting humans were reported by Lubbe et al.
in which a ferrofl uid (size about 100 nm) was coated with starch polymers and anionic phosphate
groups to load the drug epirubicin. In only approximately 30 min, the ferrofl uids were successfully
directed to the tumor sites in half of the patients. Similar investigations using liposomes containing
magnetic nanoparticles and drugs have also been reported [60]. The effi cacy of magnetic therapy
is dependent on the applied fi eld strength as well as on the volumetric and magnetic properties of
the particles [2].
6.3.4.3
Ceramic Nanoparticles
Inorganic, porous, ceramic nanoparticles have several advantages in cancer therapy. These particles
can be easily engineered with the desired size, shape, and porosity, and they are extremely inert.
The ceramic materials used are biocompatible and can be easily modifi ed with different functional
groups for ligand attachment [62-64]. Thus, growing interest has recently emerged in utilizing
ceramic nanoparticles as drug vehicles in cancer therapy, exploring typical biocompatible ceramic
nanoparticles, such as silica, alumina, and titania [39].
The luminescent silica nanoparticle has attracted the bioanalysis area recently. Its extensive
application is based on the immobilization of various biomolecules such as DNA, antibody, and so
forth, onto the surface. Liu et al. introduced amine groups onto the silica nanoparticle surface. Then,
mouse monoclonal antihuman CD71 antibody (McAb CD71) and transferrin (Tf) were effectively
linked and successfully labeled the receptors in the membrane of fi broblasts [65].
Roy et al. revealed that silica-based nanoparticles doped with photosensitizing drugs can be
used for applications in photodynamic therapy. The spherical and highly monodispersed silica-
based nanoparticles (size 30 nm) were prepared by controlled hydrolysis of triethoxyvinylsilane
in micellar media [62]. Paul et al. developed insulin-loaded porous hydroxyapatite nanoparticles
for intestinal delivery. Compared with repeatable injections, the insulin release profi le exhibited
promising results for orally administered insulin [63]. Recently, silica nanoparticles were used to
form ternary complexes with DNA-dendrimer, resulting in a high surface concentration of DNA in
the cell culture, and allowing effi cient uptake of DNA by an endosomal-lysomal route [64].
6.3.4.4 Metal Nanoparticles
Metal nanoparticles have the ability to carry a relatively high drug dose because they can be fabri-
cated in extremely small sizes (
50 nm) and have a large surface area. Functionalizing the surface
of conventional metal nanoparticles such as gold or silver is under investigation for drug delivery
molecules [60,66].
Increasing interest in polyelectrolyte multilayer research (PEM) is stimulated by the potential
applications of this technology in the area of drug delivery. Microcapsules are fabricated by the
layer-by-layer technique through the alternate adsorption of oppositely charged polyelectrolytes on
various colloidal templates. Subsequently, the core is dissolved and the remaining shells serve as
capsules for materials such as polymers, enzymes, catalysts, and the like. The uniqueness of such
microcontainers is that they allow for tailoring the composition of their walls including incorporation
of metal nanoparticles. Skirtach et al. proposed a novel method for remote release of encapsulated
materials based on real-time monitoring of the capsules under laser light illumination. Laser-mediated
remote release of encapsulated fl uorescently labeled polymers from nanoengineered polyelectrolyte
multilayer capsules containing gold sulfi de core/gold shell nanoparticles in their wall is monitored in
real time on a single capsule level [67].
Recently, Priyabara et al. demonstrated that gold nanoparticles can be functionalized into a
composite system to carry both antiangiogenic and anticancer agents [39,66].
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