The invention relates generally to biotin-containing compounds that are useful as imaging agents and drug-delivery agents. Another aspect of the invention relates to the aforementioned compounds chelated to a metal atom. In a preferred embodiment, the metal atom is a gadolinium. Another aspect of the invention relates to a compound comprising three biotin moieties and a pharmaceutical agent covalently bound to a heterocyclic core. In certain embodiments, the pharmaceutical agent is an antibiotic, antiviral, or radionuclide. Another aspect of the present invention relates to a method of treating disease involving administering the compounds of the invention to a mammal. Another aspect of the present invention relates to a method of acquiring a magnetic resonance image using the compounds of the invention.