SNAP-targeted MRI-Fluorescent agents for multimodal imaging.

Magnetic resonance imaging (MRI) is a powerful imaging modality, highly employed in research and clinical settings. However, MRI images suffers from low signals and lack of target specificity. We aimed to develop a multimodal imaging probe to detect targeted-cells by MRI and fluorescence microscopy. We synthesized a tri-functional imaging probe consisting of a SNAP-tag substrate for irreversible and specific labeling of cells, cyanine dyes for bright fluorescence, and a chelated Gd(III) molecule for enhancing MRI-contrast. Our probes exhibit specific and efficient labelling of genetically-defined cells (expressing SNAP at their membrane), bright fluorescence and MRI signal. Our synthetic approach provides a versatile platform for production of multimodal imaging probes, particularly for light microscopy and MRI.