9 Jun 2011

Magnetic Nanoparticles

Magnetic nanoparticles (mNPs) are microscopic particles manipulated with magnetic fields. Composed of magnetic elements (i.E., iron, nickel and cobalt) or compounds of such elements, mNPs are usually less than 1 micrometer wide, although larger particles can measure as much as 500 micrometers in diameter. Recently, particles of this type have been a major focus of research.

With the design of 'theranostic' molecules, mNPs will play a crucial role in developing one-stop tools to simultaneously diagnose, monitor and treat a wide range of common diseases and injuries.
Multifunctional particles, modeled on viruses such as those that cause flu and HIV, are being researched and developed to carry signal-generating sub-molecules and drugs to particular targets. A sprinkling of tiny mNPs, an application of external magnetic force, and presto! - a new means of confirming specific ailments or releasing drugs at exact points within a living system.

The magnetic component of the direction-giving nanoparticles is usually an iron-based compound called ferric oxide wrapped in a bio-compatible envelope, for example, a light coating of friendly fatty acids to provide stability during the particle's journey through the body. For biomedicine, the mNPs are extremely useful because you can add specific signal triggering molecules to identify certain conditions, or dyes to help in medical imaging, or therapeutic agents to zap a tumor.

Already mNPs have sparked interest after being attached to stem cells and used in vivo to remedy heart injury in rats. In humans, Berlin's Charité Hospital used a technique which involved mNPs, called hyperthermia, to destroy a particularly severe form of brain cancer in 14 patients. The technique - which took advantage of the fact that tumor cells are more sensitive to temperature increases than normal cells - sent mNPs acting as nano-heaters directly against the inoperable tumors and essentially cooked them to death.

Magnetic nanoparticles are tiny. This 15 nm
FeO magnetic nanoparticle has a diameter
About 1/7000th that of a human hair..

Due to the fact that bound and unbound nanoparticles have different magnetic relaxation times, biochemical binding reactions can be detected by means of a SQUID-high resolution measurement technique. Magnetic relaxation immunoassays (MARIA) were recently realized by means of this technique. Also in vivo-applications of magnetorelaxometry seem possible, e.G. In cancer diagnostics.

Immobilisation of magnetic nanoparticles by antibody-antigen coupling

So magnetic nanoparticles will almost certainly have an important role in the future of medicine.

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