Biomedical applications of mesoscale magnetic particles

Mesoscale (nanometers to microns) magnetic particles are becoming increasingly important in biomedical applications both in vitro for cell and tissue-based research and in vivo for clinical imaging and therapy. These applications generally rely on the fact that, while the body is relatively transparent to magnetic fields, magnetic particles within the body, or in ex vivo biological samples, will couple strongly to applied external fields. By synthesizing bio-functionalized, biocompatible polymer/magnetic particle composites, this remote coupling provides a mechanism for the precisely targeted actuation of cell signaling pathways, delivery of genes, targeted transmission of thermal energy, generation of tissue matrix, and imaging (via magnetic resonance imaging), among others. This article explores a variety of biomedical applications of mesoscale magnetic particles, some of which are routinely used in the clinic and in biomedical laboratories, with others approaching the realm of science fiction.