Download magnetic nanoparticles

By
Basem Mohammed Aqlan
Student No. : 432108215
&
Khaled Mohammed Humadi
Student No. : 432108263
Submitted to: Prof. Abdel Fattah Sheta
January 12, 2013
Introduction to magnetic nanoparticles
 What are magnetic nanoparticles?
 The type of magnetic nanoparticles
 Characterizing nanoparticles
Biomedical applications
 Targeted drug delivery
 Magnetic hyperthermia
 MRI contrast agent
 Magnetic separation
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The magnetic nanoparticles are spheres of a magnetic
material in the size of nanometers.
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suitably coated with molecules to increase their
biocompatibility, and dipped in a fluid that facilitates
their injection in situ or in the systemic circulation.
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Magnetic nanoparticles can be formed by means of a
magnetic nucleus of single or multidomain type.
Magnetic nanoparticles offer some attractive possibilities in
biomedicine:
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They have controllable sizes ranging from a few
nanometres up to tens of nanometres, which places them at
dimensions that are smaller than or comparable to those of
a cell (10–100µm), a virus (20–450nm), a protein (5–
50nm) or a gene (2nm wide and 10–100nm long).
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Magnetic nanoparticles obey Coulomb’s law, and can be
manipulated by an external magnetic field gradient.
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The magnetic nanoparticles can be made to resonantly
respond to a time-varying magnetic field.
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iron oxide-based nanoparticles (Fe3O4, CFe2O3)
transition metal ferrites nanoparticles
(MFe2O4)
metal alloys nanoparticles (FeCo, FePt)
metal nanoparticles (Fe, Co, Ni)
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Magnetic nanoparticles can stick together if they
collide. This can lead to agglomeration, which is
generally detrimental for applications.
In order to prevent agglomeration, nanoparticles are
often coated with some material to prevent
agglomeration (either because of steric or electrostatic
effects).
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Because of their small size, magnetic nanoparticles
often exhibit complicated hydrodynamic properties
when suspended in solution. Fortunately, the problem
of understanding small particles in solution was solved
by Einstein many years ago.
However, since magnetic nanoparticles are sensitive to
magnetic fields, applied fields can produce additional
magneto hydrodynamic effects that are absent in nonmagnetic nanoparticles.
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An external magnetic field gradient will produce a force on magnetic
nanoparticles. There is considerable interest in using this effect for targeted
drug delivery by attaching the drug to the magnetic nanoparticles, then
applying a large magnetic field to the desired region (e.g. a cancerous
tumor or damaged joint), which will attract the magnetic nanoparticles,
hence also attract the attached drug.

It is safe to apply relatively large static dc magnetic fields to patients.
Furthermore, even ac magnetic fields may be safe, as long as the
frequencies are not too high nor the field amplitudes too large.
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This application requires attaching the drug to the magnetic nanoparticles
without (strongly) deteriorating the magnetic response of the composite or
the efficacy of the drug.
Magnetic nanoparticles will be
attracted to regions of high field
gradients.
The field gradients are largest close
to the magnet, so this approach is
most readily used to accumulate
nanoparticles near external
surfaces.
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Magnetic hyperthermia involves dispersing magnetic particles
throughout the target tissue and then applying an AC magnetic field
of sufficient strength and frequency to cause the particles to heat by
magnetic hysteresis losses or Néel relaxation
It becomes important in cancer therapy.
Cells of a certain type will be heated up to about 43°C, at which
temperature they will die.
The surrounding tissue is not involved and therefore this method is
much more protective.
The magnetic moments on nanoparticles will align with an external
magnetic field. As the external field changes direction, the magnetic
moment will also change direction. This produces dissipation
leading to heating. One of the major advantages of using magnetic
fields to produce heating is that they readily penetrate tissue.
The therapy by hyperthermia is based on the fact that tumor cells
are more sensitive to sudden changes of temperature than healthy
cells, and consequently tumor cells will die first when heated by
hyperthermia
Magnetic Resonance Imaging(MRI) : basic principle
Conventional magnetic resonance imaging (MRI) is based on the radiofrequency
signal that is transmitted from the atomic nucleus of hydrogen atoms placed in a
magnetic field and after they have been excited by a radiofrequent
electromagnetic pulse.
external
magnetic field
Cryogenic magnet
Hydrogen proton
has a magnetic moment
Hydrogen proton transmits
a radiofrequent electromagnetic
wave (yellow) after excitation
by an RF pulse (red)
Radiofrequency coil
Gradient coil
Water molecule
Cross-section of an NMR scanner
The electromagnetic signal transmitted
by the hydrogen protons is received by
the scanner and processed...
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As magnetic nanoparticles respond to external magnetic field
gradients, it may be possible to magnetically tag certain objects, and
then extract these from a flowing mixture using magnetic fields.
One advantage of this approach compared to other separation
methods is that the external magnetic can be turned on and off,
allowing the separation between tagged and untagged objects to be
well controlled.
 Also important to understand the magnetohydrodynamics
for this application, since these will strongly affect the separation
rate, etc.
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Nanoparticles have very special properties that make them attractive for
nanomedicine.
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Nanoparticles can be functionalized with antibodies to target their binding toward
specific cells.
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Nanoparticles can respond to external radiation and release heat, killing cells
around them.
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Targeted nanoparticles offer a light of hope for the fight against cancer.
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An ideal nanoparticle is three-modal: detects, diagnoses and attacks tumorous cells.