The aim of this PhD project is to develop novel nanoparticulate theranostic agents for use in targeted drug delivery, monitored by Magnetic Resonance Imaging (MRI). Theranostic agents are hybrid nanoparticle structures that combine both therapeutic and diagnostic components. Nanomedicine offers the potential to create nanocarrier materials which can incorporate both therapeutic drug molecules and diagnostic imaging agents in their structures. Such advanced material research would allow for disease site specific drug delivery and monitoring of the disease during and following therapeutic intervention, accelerating the transition from conventional medicine towards personalised, precision medicine.