MOLECULAR IMAGING

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Molecular imaging is an exciting and rapidly expanding field that is yielding major scientific and medical breakthroughs. At the heart of the field is research and development into the chemistry and chemical biology of medical isotopes and molecular imaging probes.

In the Valliant group we seek to develop new synthetic methods and technology-based platforms that facilitate the preparation and discovery of novel molecular imaging probes. Our work includes innovations in coordination chemistry, organic synthesis and in chemical biology around the discovery of agents that have high affinity for proteins specifically associated with diseases like cancer.

An Inorganic Building Block for Preparing Molecular Imaging and Therapy Agents

Carboranes are polyhedral clusters composed of BH and CH units that range in size from the small trigonal bipyramidal H2C2B3H6 cluster to substantially larger compounds. Among these, the most familiar molecule is the icosahedral dicarbadodecaborane H2C2B10H10 better known as closo-ortho-carborane, or simply “carborane” (shown below).

Carborane-1

 

Molecular imaging techniques are used to non-invasively visualize biological structures and processes.1 Utilizing the affinity of molecular species for a particular biological entity allows for the concentration of a tracer at a specific site or target. This interaction can give information about the presence or absence of a disease or condition.2 Radionuclides are ideal targeting agents because only a very small amount of material is required to produce a signal, thus minimizing the impact on the patient. In addition, the radioactive decay of the imaging agent can be monitored externally to give information about the distribution of the compound inside the subject. The identity of the radionuclide determines the method used to measure the decay, positron emission tomography (PET) is used for positron emitters such as 18F, and single photon emission computed tomography (SPECT) is used for photon emitters such as 99mTc. Both techniques are more sensitive than traditional imaging methods (CT, MRI), thereby offering the possibility of diagnosis and treatment for conditions that were previously undetected.