ABSTRACT
Fullerenes are closed carbon spheres that are being actively pursued globally for a wide range of applications. Empty cage fullerenes (Figure 9.1a and b) have unique electrochemical properties and have a wide range of potentially benecial biologic properties. Another type of fullerene can have metals enclosed inside them (metallofullerenes). Fullerenes have a unique cage structure with delocalized π molecular orbital electrons. This structure confers unusual activity in electron transfer systems due to their low reorganization energy, low lying excited states (singlet and triplet), and extended triplet lifetimes. Further, the spherical conguration of the planar benzene rings imposes an unusual constraint on these π electron orbitals. The fullerene carbon cage is insoluble and thus must be derivatized (simply meaning moieties or side groups must be added to the carbon cage) in order to make them water soluble and compatible in biological systems. The ability of fullerenes to be derivatized with side chains provides opportunities to diversify, manipulate, and harness the
9.1 Fullerenes as a Platform for New Solutions in Several Scientic Areas ...... 147 9.2 Fullerenes for Therapeutics .......................................................................... 148
9.2.1 The Ability of Fullerene FDs to Affect Mast Cell-Driven, Allergic Inammatory Disease ........................................................ 149
9.2.2 MC and PBB in Asthma ................................................................... 149 9.2.3 MCs in Arthritis ............................................................................... 152 9.2.4 MCs in Multiple Sclerosis and Fullerenes ........................................ 154
9.3 Fullerenes for Diagnostics ............................................................................ 155 9.3.1 Metallo-Fullerenes as New Contrast Agents .................................... 155 9.3.2 Metallo-Fullerenes MRI Contrast Agents as Diagnostics
for Atherosclerotic Plaque ................................................................ 156 9.4 Fullerenes for Theranostics .......................................................................... 157
9.4.1 Metallo-Fullerenes MRI Contrast Agents as Theranostics for Brain Cancer ..................................................................................... 157
9.5 Future Directions with Fullerenes ................................................................ 158 References .............................................................................................................. 161
electronic properties of the cage for selected applications. Of course, each derivation results in changes in the compounds physical and chemical property including; for example, particle size/length, zeta potential, net charge, molecular weight, purity, surface characteristics, and solubility. Too often, results from studies examining the effects of fullerenes on biological systems tend to be extrapolated into other applications. As demonstrated below, each fullerene derivative (FD) must be assessed separately depending on the biological application. Even extremely similar derivatized fullerenes can have completely opposite results, which stimulates efforts to understand how changing the chemical composition and structural arrangement of fullerenes affects molecular interactions at cellular, tissue, and organ system levels. Consequently, their inherent properties described below combined with their ability to be derivatized with side chains results in almost limitless new chemical structures making them ideal platform molecules for innovative new solutions to basic biological problems. This chapter will focus on the applications of both empty cage and metallo-fullerenes for therapeutic, diagnostic, and theranostic (combination of diagnostic and therapeutic) applications.
