There is currently a need for improved spin probes to help with the diagnosis of and fundamental research into diseases mediated by reactive oxygen species (ROS). This is especially true for the study of age related diseases, since oxidative damage accumulates during the aging process, and many age related disorders such as Parkinson's and Alzheimer's disease are characterized by damage from excess ROS. Spin probes allow these unstable oxygen species to be detected and identified using various magnetic resonance techniques, such as electron paramagnetic resonance (EPR). While certain cancers in animals (Mikuni et al., 2004) and tissues, such as an isolated rat heart (Zweier et al., 1998), have been successfully imaged using EPR imaging, (EPRI), with the current generation of spin probes it is not possible to detect the generation of ROS in age related disorders. The development of new spin probes that allow in vivo detection of ROS produced by Parkinson's and other ROS diseases would represent a significant advance for diagnosing these conditions and for guiding their treatment. To overcome limitations of current spin probe compounds, we propose to investigate spin probes based upon single paramagnetic nitrogen atoms encapsulated in C60 fullerenes, N@C60. In this species, the nitrogen is pinned at the center of the symmetric fullerene cage where its unpaired spins are completely protected from reaction with external species. Isolation from the outside environment in the fullerene cage endows N@C60 with one of the narrowest known EPR line widths, (Morton et al., 2006), giving it a detection efficiency 100 to 1000 times better than the current compounds. Reactions of ROS occurring on the surface N@C60 will produce measurable shifts in the spectrum. These combined features make N@C60 the ideal spin probe. Given its high potential to make a nearly perfect spin probe, the aim of this project is to synthesize and characterize a spin probe based on N@C60 for molecular oxygen, superoxide, and other biologically important reactive oxygen species.
The specific aims of this phase I project are: 1) First establish that it is possible to produce our candidate spin probe in quantities sufficient for testing, 2) Show that our N@C60 derivative has an EPR signal suitable for use as a spin probe, and 3) Provide preliminary data for comparison with currently available spin probes, including the detection of superoxide. ? Many age related disorders such as Parkinson's and Alzheimer's disease are characterized by damage from excess reactive oxygen species (ROS), and it is not possible with the current imaging technology to non-invasively detect the generation of ROS in people. Spin probes are molecular agents designed to react with reactive oxygen species (ROS) which enables them to be detected and identified using various magnetic resonance techniques. To overcome the limitations of current agents and enable the development of better imaging techniques for ROS disorders, we propose to investigate new types of spin probes based upon paramagnetic nitrogen atoms encapsulated in C60 fullerenes, N@C60. The development of new spin probes that allow in vivo detection of ROS produced by Parkinson's and other ROS diseases would represent a significant advance for diagnosing these conditions and for guiding their treatment. ? ? ?
