ABSTRACT
This chapter discusses properties, and applications of magnetic nanomaterials for various applications. The magnetic nanomaterials are important for biomedical applications in separation, immunoassay, and drug targeting. The surface modification of nanoparticles is required to improve their colloidal stability by overcoming van der Waals and magnetic dipole–dipole attractive forces. Usually paramagnetic gadolinium and superparamagnetic iron oxide nanoparticles coated with dextran have been used to enhance the contrast in nuclear magnetic resonance imaging. The separation of entities from their surroundings is based on the difference in the susceptibility between a magnetically labeled entity and the surrounding medium, i.e., shorting of magnetic cell for cellular therapy and immunoassay. The magnetic susceptibility of these superparamagnetic particles is many orders of magnitude larger than bulk paramagnetic materials. The coercivity of a superparamagnetic particle is zero because thermal fluctuations prevent the existence of a stable magnetization.
