In situ activation of a doxorubicin prodrug using imaging-capable nanoparticles.

A general strategy for image-guided prodrug activation using fluorescently-labeled magnetic iron oxide nanoparticles is described. It is based on a recently developed concept in bio-orthogonal inverse-electron demand Diels-Alder chemistry, which is termed 'click-to-release'. To illustrate a potential new biomedical application of the chemistry, the nanoparticles were modified with tetrazine, as well as near infrared fluorescent (NIRF) cy5.5 dye, while doxorubicin was converted into a prodrug. The nanoparticles taken up by the MDA-MB-231 breast cancer cells efficiently converted the prodrug of doxorubicin into the biologically active chemotherapeutic doxorubicin form.