Luminescent lanthanide chelate contrast agents and detection of lesions in the hamster oral cancer model

Lanthanide chelates are a somewhat unique class of molecules that have proven to be useful in the biomedical field due to their extremely large Stokes' shift and long fluorescent lifetimes. The ability of these molecules to produce fluorescence in the low- or zero-background regime makes this class of molecules excellent candidates for use as contrast agents for a wide variety of applications in biological settings. Here we present the preparation, spectroscopic characterization, and application of a new terbium chelate contrast agent, based on the 1,4,7,10-tetraazacyclododecane macrocycle (cyclen), for detection of early-stage malignant lesions in the Syrian hamster cheek pouch. Tb-P(CTMB) delivers bright blue-green luminescence when excited with low photon fluxes of UV light. As a pilot study, the DMBA-treated Golden Hamster Cheek pouch epithelial cancer model was employed and Tb-P(CTMB) was used as a topical agent for the visual detection of diseased tissue. In this preliminary study the agent tended to associate with early-stage malignant lesions, suggesting that Tb-P(CTMB) could be used as a contrast agent to aid in identifying early-stage oral cancer lesions.