Biomedical Polyhedral Borane Chemistry

The traditional use of organic chemistry as the mainstay of all aspects of contemporary biomedical chemistry has provided truly miraculous results. However, advances in the closely related area of aromatic polyhedral borane chemistry (polyhedral ions, carboranes, metallacarboranes, metallaboranes and other heteroatom derivatives) has now provided the basic discoveries necessary for the assembly of a totally new set of biomedically unique structures and reactions for immediate use. Thus, while some polyhedral borane derivatives may be employed across the wide spectrum of biomedicine in much the same way as organic compounds, the former species present unusual chemical, biochemical and physical properties which provide enhanced and often unique performance. More importantly, totally new biomedical applications as well as novel solutions to old problems emerge. In short, polyhedral borane chemistry provides an additional set of opportunities to assist medical science by utilizing a surrogate for carbon chemistry. Notable biomedical applications of this emerging chemistry impinge upon such representative topics as positron emission tomography (PET), enzyme impervious agents for radioimaging and radiotherapy, new drug delivery agents for targeting the cell nucleus, use of the cytotoxic boron-10 neutron capture reaction for cancer (BNCT) and arthritis (BNCS) therapies, new drug and diagnostic agent delivery vehicles based upon multivalent cell-targeted unimolecular nanoparticles (closomers and liposomes) and the design and synthesis of catabolism-proof structural modules for incorporation in new pharmaceuticals. These and other related topics are presently under investigation in the Hawthorne Laboratory. An example of the continuing development of one such subject which involves tumor imaging is presented immediately below.