Parahydrogen-Induced Polarization

Pratip Bhattacharya, Ph.D.
Huntington Medical Research Institute

Parahydrogen-Induced Polarization (PHIP) or Parahydrogen And Synthesis Allow Dramatically Enhanced Nuclear Alignment (PASADENA)1 is a liquid state chemical technique of hyperpolarization which can be accomplished in seconds at room temperature. Dynamic Nuclear Polarization (DNP) is a solid state method of hyperpolarization where polarizations takes place at low temperature, high magnetic field, and with unpaired electron of selected species (e.g. triaryl radical) to produce strongly polarize nuclear spins in the solid state in hours. The solid sample is subsequently dissolved rapidly in water to create a solution of molecules with hyperpolarized nuclear spins.2 DNP polarizer is now commercially available from Oxford Instruments. PHIP is usually accomplished in home-made polarizer systems.3,4 PHIP is limited to molecules with unsaturation (double or triple bonds) while DNP is a more general method and may be applied to a wider range of molecules. PHIP is a relatively inexpensive method of hyperpolarization compared to DNP and since the polarization can be accomplished in seconds to minutes in the PHIP polarizer-this technique can be used for several experimental trials within a short period of time. Both DNP and PHIP have been used for in vivo applications and real time metabolic and molecular imaging.


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  1. Bowers, C. R.; Weitekamp D. P.; Parahydrogen And Synthesis Allow Dramatically Enhanced Nuclear Alignment. J. Am. Chem. Soc. 1987, 109, 5541–5542.
  2. Ardenkjaer-Larsen, J. H.; Fridlund, B.; Gram, A.; Hansson, G.; Hansson, L.; Lerche, M. H.; Servin, R.; Thaning, M.; Golman, K.; Increase in signal-tonoiseratio of >10,000 times in liquid-state NMR. Proceedings of the National Academy of Sciences of the United States of America 2003, 100(18), 10158–10163.
  3. Hovener, J. B.; Chekmenev, E. Y.; Harris K., Perman, W. H.; Robertson, L., Ross, B. D.; Bhattacharya, P. PASADENA Hyperpolarization of 13C Biomolecules: Equipment Design and Installation. Magn Reson Mater Phy 2009, 22:111–121.
  4. Hovener, J. B.; Chekmenev, E. Y.; Harris, K.; Perman, W. H.; Ross, B. D.; Bhattacharya, P. Quality Assurance of PASADENA Hyperpolarization for 13C Biomolecules. Magn Reson Mater Phy, 2009, 22:123–134.


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