"Luminescence is an attractive strategy for a low cost, real-time and unambiguous detection of cancer cells and tumors due to its high sensitivity and the versatility of the instrumentation. The actual bottleneck is related to the imaging agents whose performances directly control the sensitivity and the selectivity of the real-time detection in living biological systems. Lanthanide luminescence offers several important advantages over organic fluorophores and semiconductor nanocrystals: (i) sharp emission bands for spectral discrimination from autofluorescence and multiplex detection, (ii) emission in the near-infrared, (iii) long luminescence lifetime for temporal discrimination, and (iv) strong resistance to photobleaching. The main idea of this proposal is to create and use new dendrimer lanthanide-based luminescent imaging agents to establish a novel modality of in vivo cancer cells and tumor detection. The proposed work includes the design of luminescent dendrimer complexes, the detailed investigation of their spectroscopic properties, as well as the in vivo tests at the cellular (microscopy) and small animals (macroscopy) levels to evaluate the performances of these imaging agents for practical applications. Proposed unique dendrimer technology is a versatile tool allowing (i) the enhancement of detection sensitivity since many lanthanide ions and lanthanide sensitizers can be combined within one discrete molecule increasing the number of photons per unit volume, (ii) the attachment of a broad variety of lanthanide sensitizers, including those allowing low energy excitation that is less harmful for biological systems, and (iii) the conjugation with a large variety of peptides for selective cancer cells and tumor targeting. Overall, successful completion of this project will result in creation of a novel lanthanide-based imaging methodology allowing real-time, selective and sensitive detection of different types of cancer tumors on the early stages."