Magnetic nanoparticles

Magnetic nanoparticles are a class of nanoparticle which can be manipulated using magnetic field. Such particles commonly consist of magnetic elements such as iron, nickel and cobalt and their chemical compounds. These particles have been the focus of much research recently because they possess attractive properties which could see potential use in catalysis , biomedicine , magnetic resonance imaging , data storage and environmental remediation . The physical and chemical properties of magnetic nanoparticles largely depend on the synthesis method and chemical structure. In most cases, the particles range from 1 to 100 nm in size and display superparamagnetism. The established methods of magnetic nanoparticle synthesis include:

1. Co-precipitation. Co-precipitation is a facile and convenient way to synthesize iron oxides (either Fe3O4 or γ-Fe2O3) from aqueous Fe2+/Fe3+ salt solutions by the addition of a base under inert atmosphere at room temperature or at elevated temperature. The size, shape, and composition of the magnetic nanoparticles very much depends on the type of salts used (e.g.chlorides, sulfates, nitrates), the Fe2+/Fe3+ ratio, the reaction temperature, the pH value and ionic strength of the media.
2. Thermal decomposition. Monodisperse magnetic nanocrystals with smaller size can essentially be synthesized through the thermal decomposition of organometallic compounds in high-boiling organic solvents containing stabilizing surfactants.
3. Microemulsion. Using the microemulsion technique, metallic cobalt, cobalt/platinum alloys, and gold-coated cobalt/platinum nanoparticles have been synthesized in reverse micelles of cetyltrimethlyammonium bromide, using 1-butanol as the cosurfactant and octane as the oil phase. 

A wide variety of applications have been envisaged for this class of particles these include:

1. Medical Diagnostics and Treatments. Magnetic nanoparticles are used in an experimental cancer treatment called magnetic hyperthermia in which the fact that nanoparticles heat when they are placed in an alternative magnetic field is used. Another potential treatment of cancer includes attaching magnetic nanoparticles to free-floating cancer cells, allowing them to be captured and carried out of the body. The treatment has been tested in the laboratory on mice and will be looked at in survival studies.
2. Magnetic immunoassay. Magnetic immunoassay (MIA) is a novel type of diagnostic immunoassay utilizing magnetic beads as labels in lieu of conventional, enzymes, radioisotopes or fluorescent moieties.

Further information

1. A.-H. Lu, W. Schmidt, N. Matoussevitch, H. Bönnemann, B. Spliethoff, B. Tesche, E. Bill, W. Kiefer, F. Schüth (August 2004). "Nanoengineering of a Magnetically Separable Hydrogenation Catalyst". Angewandte Chemie International Edition 43 (33): 4303–4306
2. A. K. Gupta, M. Gupta (June 2005). "Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications". Biomaterials 26 (18): 3995–4021
3. S. Mornet, S. Vasseur, F. Grasset, P. Verveka, G. Goglio, A. Demourgues, J. Portier, E. Pollert, E. Duguet, Prog. Solid StateChem. 2006, 34, 237
4. D. W. Elliott, W.-X. Zhang, Environ. Sci. Technol. 2001, 35, 4922
5. H. Lu, E. L. Salabas and F. Schüth, Angew. Chem., Int. Ed., 2007, 46,1222–1244
6. Scarberry KE, Dickerson EB, McDonald JF, Zhang ZJ (July 2008). "Magnetic Nanoparticle-Peptide Conjugates for in Vitro and in Vivo Targeting and Extraction of Cancer Cells". Journal of the American Chemical Society 130: 10258
7. Using Magnetic Nanoparticles to Combat Cancer Newswise, Retrieved on July 17, 2008.
8. Article Magnetic nanoparticles from Wikipedia, the Free Enciclopedia. Available under the license Creative Commons Attribution-Share Alike.

Back to Russian