Biomedical Engineering Reference
In-Depth Information
A naturally occurring substance found in the cooking spice turmeric, cur-
cumin, has long been known to have anticancer properties. However, widespread
clinical application of this anticancer agent has been limited due to its poor solu-
bility and minimal systemic bioavailability. This problem has been resolved by
encapsulating curcumin in a polymeric NP, creating “nanocurcumin.”
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Nano-
curcumin and free curcumin have been shown to affect pancreatic cancer cells
through induction of apoptosis, blockade of nuclear factor kappa B activation,
and downregulation of proinflammatory cytokines [i.e. interleukin (IL)-6, IL-8,
and TNF-α]. Thus, nanocurcumin provides an opportunity to expand the anti-
cancer applications of this agent by enabling soluble dispersion.
5.9.4 Magnetic NPs
The magnetic property of a material is the atomic or subatomic response a
material to an applied magnetic field wherein the electron spin and charge cre-
ate a dipole moment and a magnetic field.
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A magnetic field of measurable
intensity that can be recorded results when multiple dipole moments ensue. The
response of a magnetic material to an external magnetic force can be attraction
(paramagnetism) or repulsion (diamagnetism) or something more complex.
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Magnetic material structures are based on magnetic domains which are small
areas that align themselves in an applied magnetic field. Spontaneous magne-
tization occurs in paramagnetic materials (ferromagnetic and ferromagnetic)
that results in the formation of permanent magnets or gradual demagnetization.
With superparamagnetic materials, such as magnetic NPs that are the size of
magnetic domains, spontaneous magnetization and demagnetization occur
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causing a much larger response to an applied magnetic field called superpara-
magnetic behavior.
To date, the most activity in magnetic NP-based drug delivery has focused
on Fe-based NPs of the three elements (B=Ni, Co, and Fe) that are ferromag-
netic under physiological conditions. This may be attributed to the to its supe-
rior magnetic susceptibility (218 and 90 emu/g for elemental Fe and Fe
3
O
4
,
respectively), as well as the large natural reservoir of iron in the body, suggest-
ing the comparative absence of toxicity of this element.
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During the last few
years, interest on the synthesis and drug delivery applications of Fe-based NPs
has matured to in vivo studies of localization and to antitumor activity.
Magnetic NPs are ideal nanocarriers of drugs and vaccines because these
NPs can also be used to diagnose the efficacy of treatment. Dimercaptosuc-
cinic acid (DMSA)-coated monodisperse magnetic nanoparticles (MNPs) were
tested as a delivery system for the antitumorigenic cytokine interferon-gamma
IFN-γ in mouse models of cancer.
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Using an external magnetic field, the IFN-
γ-adsorbed DMSA-coated MNPs that were targeted to the tumor site showed a
high degree of NP accumulation and of cytokine delivery at the tumor site. This
caused an increased T cell and macrophage infiltration that promoted an anti-
angiogenic effect. This led to a notable reduction in tumor size indicating that
