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US 7,351,402 B2Granted
Polarizing agents for dynamic nuclear polarization
AssigneeMassachusetts Institute of Technology
InventorsRobert G. Griffin, Kan-Nian Hu
Life of this patent
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Abstract
We describe polarizing agents for use in enhancing NMR and MRI signals via dynamic nuclear polarization (DNP). The polarizing agents include two or more paramagnetic centers, preferably two paramagnetic centers. In a preferred embodiment, the polarizing agent comprises two nitroxide radicals tethered by a polyethylene glycol chain of variable length. Signal enhancements of up to 175 have been achieved in comparison with factors of ˜45 at similar concentrations of monomeric radical such as TEMPO.
Claims20
A method comprising steps of:
- placing a sample that includes a polarizing agent within a magnetic field, wherein the polarizing agent is a ground state triplet molecule which comprises two or more unpaired electrons and at least two of the unpaired electrons have spin resonance frequencies that are separated by the spin resonance frequency of a selected nucleus within the sample;
- and
- irradiating the sample with radiation that causes a mutual electron spin flip of the at least two unpaired electrons in combination with a nuclear spin flip of the selected nucleus so that the nuclear polarization of the selected nucleus is enhanced.
Dependencies are inferred from the claim text.