Electromagnetic interactions with magnetic nanoparticles: in biomedicine Applications By Basem Mohammed Aqlan Student No. : 432108215 & Khaled Mohammed Humadi Student No. : 432108263 Submitted to: Prof. Abdel Fattah Sheta January 12, 2013

Outlines 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

Magnetic Nanoparticles The magnetic nanoparticles are spheres of a magnetic material in the size of nanometers. suitably coated with molecules to increase their biocompatibility, and dipped in a fluid that facilitates their injection in situ or in the systemic circulation. Magnetic nanoparticles can be formed by means of a magnetic nucleus of single or multidomain type.

Magnetic Nanoparticles Magnetic nanoparticles offer some attractive possibilities in biomedicine: 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). Magnetic nanoparticles obey Coulomb’s law, and can be manipulated by an external magnetic field gradient. The magnetic nanoparticles can be made to resonantly respond to a time-varying magnetic field.

Types of magnetic nanoroparticles iron oxide-based nanoparticles (Fe3O4, C- Fe2O3) transition metal ferrites nanoparticles (MFe2O4) metal alloys nanoparticles (FeCo, FePt) metal nanoparticles (Fe, Co, Ni)

Characterizing of magnetic Nanoparticles 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).

Characterizing of Magnetic Nanoparticles 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 non- magnetic nanoparticles.

Biomedical applications

Targeted Drug Delivery 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. 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.

Targeted Drug Delivery 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.

Magnetic hyperthermia 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. Hydrogen proton has a magnetic moment external magnetic field Hydrogen proton transmits a radiofrequent electromagnetic wave (yellow) after excitation by an RF pulse (red) Cryogenic magnet Radiofrequency coil Gradient coil Water molecule The electromagnetic signal transmitted by the hydrogen protons is received by the scanner and processed... Cross-section of an NMR scanner

Magnetic Separation 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.

What have we learned? Nanoparticles have very special properties that make them attractive for nanomedicine. Nanoparticles can be functionalized with antibodies to target their binding toward specific cells. Nanoparticles can respond to external radiation and release heat, killing cells around them. Targeted nanoparticles offer a light of hope for the fight against cancer. An ideal nanoparticle is three-modal: detects, diagnoses and attacks tumorous cells.