Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 146

Magnetic properties have not traditionally played an important role in the development of biomaterials but the interesting and improved properties observed for nanoparticles and nanostructured materials have generated considerable interest in the use of magnetic nanoparticles for biomedical applications. Magnetic nanoparticles are being considered for a variety of biomedical applications such as drug delivery, hyperthermia treatment of tumors and contrast agents for magnetic resonance imaging (Pankhurst et al. 2003).

Magnetism is commonly viewed as an attraction or repulsion between two materials. Whereas all materials are magnetic to some extent, the magnetism that we know from daily experience, such as iron filings or nails attracted to a bar magnet, is an important but special type of magnetic behavior called ferromagnetism. This type of magnetism is relevant to biomedical applications of magnetic nanoparticles and to engineering applications as well but there are weaker forms of magnetism called paramagnetism and diamagnetism. These different types of magnetism have their origins in the atomic structure of the constituent atoms or ions of the material. It is useful to understand how they arise in order to control or improve the magnetic properties of materials used as biomaterials.