Radiation Interactions and Dosimetry Group
Buckyball Production
The nature of fullerenes as miniature "isolation chambers" suggests
the possibility of radionuclides carried within the interior of the molecular
cage, forming "radioendofullerenes." Along with ultra-low level
radiation detection methods such as MultiPhoton Detection (MPD), the
containment of radionuclides within a stable, all-carbon shell may allow the
development of a new family of radiotracers and, with the appropriate
biomolecule derivative, site-specific radioimagers. Fullerene synthesis using
the Kratschmer-Huffman method is carried out in the Fullerene Production
Chamber (FPC, shown above) using high-current arc-burning of doped graphite
rods in a helium atmosphere. We have produced and characterized endofullerenes
containing the radionuclide 99mTc
(T1/2 = 6 h, E g = 140 keV)
which is of particular interest in nuclear medicine imaging studies throughout
the body. In addition to radioendofullerenes, we have made
"radioheterofullerenes," in which one or more stable carbon atoms of
the fullerene cage itself are converted to the radionuclide 11C by
photonuclear isotope production. The two 511 keV photons emitted due to
the positron annihilation upon the decay of 11C to 11B
(T1/2 = 20.4 min) make these radiofullerenes ideally
suited for coincidence detection methods. A series of 11C
radiofullerenes Cn-111C (n = 60, 70, 76 to 84)
have been successfully formed by electron/bremsstrahlung beam irradiation of
purified fullerenes, suggesting the use of radiofullerene species of various
diameters in nanoporosity characterization and radiotracing applications.
Ultimately, the use of several radionuclides emitting different photon energies
or having different half-lives encapsulated in carbon cages of various sizes
could provide a "multicolored" system with which different targets
can be imaged or treated simultaneously with multiple radionuclides.
For information contact:
Dr. Lisa Karam
[lisa.karam@nist.gov]
REFERENCES
- Karam, L.R., Mitch, M.G., and Coursey, B.M., "Encapsulation of
99mTc within Fullerenes: a Novel Radionuclidic Carrier,"
Appl. Radiat. Isot. 48, 771 (1997).
- Mitch, M.G., Karam, L.R., Coursey, B.M., and Sagdeev, I., "Production of
11C in Fullerene Cages: Short Half-Life Tracers," Fullerene
Science and Technology 5(5), 855-869 (1997).
Return to:
Gallery |
Radiation Interactions and Dosimetry
Group |
Ionizing Radiation Division
Inquiries or comments:
s.seltzer@nist.gov
Online: October 20, 1997 - Last update: March 2005
|
