Jan 31, 2011

Fast Characterization of Functionalized Silica Materials by Silcion-29 Surface-Enhanced NMR Spectroscopy Using Dynamic Nuclear Polarization

M. Lelli et al., Fast Characterization of Functionalized Silica Materials by Silcion-29 Surface-Enhanced NMR Spectroscopy Using Dynamic Nuclear Polarization, J. Am. Chem. Soc., 2010,

We demonstrate fast characterization of the distribution of surface bonding modes and interactions in a series of functionalized materials via surface-enhanced nuclear magnetic resonance spectroscopy using dynamic nuclear polarization (DNP). Surface-enhanced silicon-29 DNP NMR spectra were obtained by using incipient wetness impregnation of the sample with a solution containing a polarizing radical (TOTAPOL). We identify and compare the bonding topology of functional groups in materials obtained via a sol-gel process and in materials prepared by post-grafting reactions. Furthermore, the remarkable gain in time provided by surface-enhanced silicon-29 DNP NMR spectroscopy (typically on the order of a factor 400) allows the facile acquisition of two-dimensional correlation spectra.

In Situ Detection of PHIP at 48 mT: Demonstration Using a Centrally Controlled Polarizer

K. W. Waddell et al., In Situ Detection of PHIP at 48 mT: Demonstration Using a Centrally Controlled Polarizer, J. Am. Chem. Soc., 2010, 133(1), 97-101

Presented here is a centrally controlled, automated parahydrogen-based polarizer with in situ
detection capability. A 20% polarization, corresponding to a 5 000 000-fold signal enhancement at 48 mT, is demonstrated on 2-hydroxyethyl-1-13C-propionate-d2,3,3 using a double-tuned antenna and pulsed polarization transfer. In situ detection is a refinement of first-generation devices enabling fast calibration of rf pulses and B0, quality assurance of hyperpolarized contrast agents, and stand-alone operation without the necessity of high-field MR spectrometers. These features are essential for biomedical applications of parahydrogen-based hyperpolarization and for clinical translation. We demonstrate the flexibility of the device by recording 13C signal decay due to longitudinal relaxation of a hyperpolarized contrast agent at 48 mT corresponding to 2 MHz proton frequency. This appears to be the longest recorded T1 (101 +/- 7 s) for a 13C hyperpolarized contrast agent in water.

Jan 28, 2011

Determination of the temperature dependence of the dynamic nuclear polarisation enhancement of water protons at 3.4 Tesla

Eugney V. Kryukov, Kevin J. Pike, Thomas K. Y. Tam, Mark E. Newton, Mark E. Smith and Ray Durpee

It is shown that the temperature dependence of the DNP enhancement of the NMR signal from water protons at 3.4 T using TEMPOL as a polarising agent can be obtained provided that the nuclear relaxation, T1I, is sufficiently fast and the resolution sufficient to measure the 1H NMR shift. For high radical concentrations (~100 mM) the leakage factor is approximately 1 and,provided sufficient microwave power is available, the saturation factor is also approximately 1. In this situation the DNP enhancement is solely a product of the ratio of the electron and nuclear gyromagnetic ratios and the coupling factor enabling the latter to be directly determined. Although the use of high microwave power levels needed to ensure saturation causes rapid heating of the sample, this does not prevent maximum DNP enhancements, e0, being obtained since T1I is very much less than the characteristic heating time at these concentrations. It is necessary, however, to know the temperature variation of T1I to allow accurate modelling of the behaviour. The DNP enhancement is found to vary linearly with temperature with e0(T) = -2 +/- 2 - (1.35 +/- 0.02)T for 6ºC < T < 100ºC. The value determined for the coupling factor, 0.055 +/- 0.003 at 25ºC, agrees very well with the molecular dynamics simulations of Sezer et al. (Phys. Chem. Chem. Phys., 2009, 11, 6626) who calculated 0.0534, however the experimental values increase much more rapidly with increasing temperature than predicted by these simulations. Large DNP enhancements (e0 > 100) are reported at high temperatures but it is also shown that significant enhancements (e.g. ~40) can be achieved whilst maintaining the sample temperature at 40ºC by adjusting the microwave power and irradiation time. In addition, short polarisation times enable rapid data acquisition which permits further enhancement of the signal, such that useful liquid state DNP-NMR experiments could be carried out on very small samples.

Jan 26, 2011

EUROMAR 2011 in Frankfurt/Germany

Please mark your calendars, the EUROMAR 2011 will be held this year in Frankfurt/Germany from August 21st to 25th. The conference will be held in conjunction with the 33rd Discussion Meeting of the Magnetic Resonance Spectroscopy Division of the Gesellschaft Deutscher Chemiker (GDCh). Furthermore, the EUROMAR will be accompanied for the first time by the 8th European Federation of EPR Groups Meeting, a triennial meeting of all European EPR Groups and the Meeting of the International EPR Society.

The conference will cover all aspects of magnetic resonance spectroscopy such as methodological and technical advancements as well as new areas of application in material and life sciences, physics, chemistry and biology. Registration and abstract submission are open now. For further details please visit www.euromar2011.org.

Jan 21, 2011

NIH and NSF Funding for DNP Research

Dynamic Nuclear Polarization (DNP) is no new research area, however, it currently experiences a renaissance because more and more high-frequency terahertz (THz) instrumentation. became available  in recent years. This progress can be monitored by the amount of money that the U.S. National Institutes of Health (NIH) and the U.S. National Science Foundation (NSF) spent on DNP research in recent years.
Over the last decade, the two government agencies NIH and NSF spent a total of more than 59 M$ on DNP research and DNP related topics. While the funding amount between the years 2000 and 2005 is almost constant (average of 2.9 M$/yr), with no significant contribution by the NSF, funding level significantly increased over the last five years. So far 2010 has been the year with the highest funding rate ever, with almost 14 M$ spent on DNP research.
The majority of the money went into individual research grants such as NIH’s R01 grants. However, in recent years more projects were funded using the NIH S10 (shared instrumentation) or P41 (center grant) funding mechanisms, indicating that a significant portion was spent on turn-key instrumentation as supposed to individual research grants.
Finally, the majority of the 59 M$ dollars went to institutions in Massachusetts (34.2 M$, 58 %) and California (7.7 M$, 13%).
These data are available free of charge from the NIHReporter or the NSF funding database. The raw data of this study are available upon request.

Jan 6, 2011

DFG Announces Solicitation for DNP Instrumentation

The Deutsche Forschungs Gemeinschaft (DFG) announced that it will accept proposals to fund high-frequency solid-state NMR spectrometers for DNP-enhanced SSNMR spectroscopy. The goal is to provide German Universities fast access to this new and exciting technology. Further information can be found here.

Submission deadline is March 31st, 2011