Magnet-targeted delivery and imaging

Abstract

Magnetic nanoparticles, in combination with applied magnetic fields, can non-invasively focus delivery of small-molecule drugs and human cells to specific regions of the anatomy. This emerging technology could solve one of the main challenges in therapy development: delivery of a high concentration of the therapeutic agent to the target organ or tissue whilst reducing systemic dosing and off-target side effects. Several challenges, however, must be met before this technology can be applied either effectively or safely in the clinic to augment therapies. Multiple nanoparticle features interact to influence the efficiency of magnet-targeted delivery, and so their design will have a large influence on the success of therapeutic targeting. Iron oxide core size and composition affect the type and strength of magnetism, and thus the amount of force that can be applied by an external magnetic field, while particle behaviour within biological systems can be affected by particle size and coating. Preclinical researchers have investigated the use of magnetic targeting-based therapies across a wide range of conditions, and positive results have been reported for both cell and drug delivery applications. Furthermore, magnetic resonance imaging (MRI) can non-invasively monitor the success of targeted delivery-providing high-resolution anatomical information on particle location in preclinical and clinical contexts. In this chapter, we provide a basic introduction to the physical principles behind magnetic targeting technology, relevant design features of nanoparticles and magnetic targeting devices, an overview of preclinical and clinical applications, and an introduction to imaging magnetic particles in vivo.