Theranostics: Agents for Diagnosis and Therapy

Theranostics is a rapidly expanding field and is a portmanteau of Therapeutics and Diagnostics. In a broader definition, theranostics is considered a diagnostic methodology for personalized therapeutic interventions. In a narrower and recently more frequently used definition, theranostics employs molecular targeting vectors and often nanoplatform technologies into which both diagnostic and therapeutic functionalities are incorporated. This chapter provides the reader with an outline of different theranostic approaches that have been investigated for the diagnosis and treatment of disease, with a particular focus on approaches for the treatment of cancer. We will discuss different imaging modalities and their associated contrast generating methodologies, e.g., T1 and T2 contrast agents (magentic resonance imaging), gold nanoparticles (CT and optical imaging), and nuclear agents (PET/SPECT), as well as their function as delivery vehicles for the targeted treatment of disease in vivo using a range of strategies including chemotherapy, photothermal therapy, and immunotherapy. The benefit of theranostic agents over traditional therapies is also discussed as well as our thoughts on the future direction of the field.