Magnetic targeting and ultrasound mediated drug delivery: benefits, limitations and combination.

This paper reviews the uses of magnetism and ultrasound in therapeutic delivery applications. Emphasis is placed upon magnetic nanoparticles and microbubble ultrasound contrast agents. The underlying physical principles, history, key developments and limitations of these techniques for drug and gene delivery in vitro and in vivo are explored. The combination of ultrasonic and magnetic techniques is also reviewed with particular focus on magnetic microbubbles as delivery agents with the potential to combine the advantages of both methods whilst addressing many of their limitations. Finally, results are presented from a study of a new magnetic microbubble formulation which shows great applicability as a therapeutic delivery vehicle.