A Study of Single Domain Magnetic Nanoparticles Towards Reactions by Low Frequency Magnetic Fields

Abstract

The dynamics of single domain magnetic nanoparticles cross-linked into multi-particle aggregates by organic ligands is considered. Mechanical factors of the effect of low frequency magnetic field on macro molecules attached to magnetic nanoparticles/aggregates within a suspension or gel are analyzed. The optimum conditions ensuring the best control over biochemical reactions in suspension by an external magnetic field (i.e., the ranges of frequency and magnetic field intensities, and the size of magnetic nanoparticles and shells covering them) are determined. Since the pioneering work of Stoner and Wolfforth over six decades ago, the behavior of magnetic single (or mono) domain particles has held enormous fascination. Magnetization reversal in such single domain particles occurs often via coherent rotation of spins. As a consequence of this rotation mechanism, magnetic nanoparticles show high co-ercivities, which lie between those of soft and hard permanent magnetic materials. The ability to control the magnetism in these types of particles makes them very attractive for applications, for example, in information storage. Moreover, the research on magnetic nanoparticles has raised hopes for applications in the fields of biology and medicine; for example, drug targeting, cancer therapy, lymph node imaging, hyperthermia, and so forth.