Bifunctional Agents for MRI, PET and Fluorescence Imaging and Study of Nanoparticles Formed from Water Oxidation Catalysts /

The work is divided into four parts : (1) MRI contrast agents are designed to enhance T₁ relaxivity by coupling them to dendrimers, the precise structure of which can be controlled through synthesis. Cyclen is used as a starting scaffold for the synthesis of bifunctional Gd-DOTA and Gd- DOTMA analogues. One unique side chain on the macrocycle contains an azide moiety that can be clicked to an alkyne- containing core, making a first-generation dendrimer with the potential to improve MRI efficiency. (2) PET tracers are designed to specifically coordinate ⁶⁴Cu, a positron source, while containing clickable side arms. A functionalized cross-bridge tetraazamacrocycle with two identical azide-bearing side arms can be clicked to alkynyl amino acid, which provides several advantages with respect to applications. (3) Using the results of part 1, MRI-fluorescence imaging agents are constructed. Preliminary tests determine their efficiency as bimodal agents. (4) My contributions to a separate project to investigate the fate of water oxidation catalysts under acidic conditions are described. We have synthesized and characterized four novel bifunctional MRI imaging agents to date. Preliminary studies show successful clicking of these complexes to form dendrimers. We are also currently synthesizing and optimizing a unique bifunctional PET tracer. Future work includes, but is not limited to, optimization of syntheses, full characterization of the bifunctional PET tracer, theoretical calculations of expected T₁ relaxivities of bifunctional MRI contrast agents, imaging cells in tissue-like matrices for MRI- fluorescence agents, and designing more robust water oxidation catalyst