The Valliant research group is interested in using organometallic chemistry to create new molecular imaging probes. The focus of recent work involves 99mTc, the most widely used medical isotope in diagnostic medicine. In particular we are interested in using Re to prepare luminescent organometallic probes and 99mTc to create an isostructural analogue for radioimaging. Since 99mTc and Re complexes have the same structure, it is possible to correlate optical and nuclear images using a single probe. This creates the unique opportunity to study biological processes in cells using fluorescence imaging and in living subjects using nuclear imaging all with the same construct.
As an example, our group has been developing methods to prepare new rhenium(I) and technetium(I) polypyridine complexes. In the example above, [2+1] complexes of a metal carbonyl core (M = Re and Tc) were synthesized. By changing the nature of the monodentate ligand (the “1” in [2+1]) the extent of cell uptake and distribution of the complex in vivo can be changed. This includes (middle panel) a bisphosphonate derivative that can target areas of high bone turnover (intense colour in the knees) as a way to image bone metastases. See Inorg. Chem. 2015, 54(4), 1728-1738.