Superparamagnetic nanoparticles as targeted probes for diagnostic and therapeutic applications

Superparamagnetic nanoparticles (NPs) have been attractive for medical diagnostics and therapeutics due to their unique magnetic properties and their ability to interact with various biomolecules of interest. The solution phase based chemical synthesis provides a near precise control on NP size, and monodisperse magnetic NPs with standard deviation in diameter of less than 10% are now routinely available. Upon controlled surface functionalization and coupling with fragments of DNA strands, proteins, peptides or antibodies, these NPs can be well-dispersed in biological solutions and used for drug delivery, magnetic separation, magnetic resonance imaging contrast enhancement and magnetic fluid hyperthermia. This Perspective reviews the common syntheses and controlled surface functionalization of monodisperse Fe₃O₄-based superparamagnetic NPs. It further outlines the exciting application potentials of these NPs in magnetic resonance imaging and drug delivery.