Jan 30, 2013

DNP symposium Denmark August 2013

Dear Colleagues 

I am happy to announce that the registration for the 4th International DNP Symposium (www.DNPsymposium.org), Copenhagen, Denmark, Aug 28-31, 2013, is now open. Registration closes May 15. 

The three day meeting will cover all aspects of Dynamic Nuclear Polarization from the basic sciences to engineering and applications. The venue of the symposium is a beautiful conference center north of Copenhagen with accommodation and meals provided in the same location. The intent is to create a stimulating environment for scientific interactions across disciplines and at all levels of career. We hope to see as many of you as possible in August. 

A preliminary program is posted along with the invited speakers list. The invited speakers are also abstract reviewers, and a blinded peer-reviewed process is applied for acceptance of the remaining oral presentations and posters. This way we aim to build a scientific program of the highest quality by transparent and fair selection. Abstract submission closes June 1, but is already open for submission. 

All the best, 
The Organizing Committee 

Lise Vejby Søgaard 
Lars G. Hanson 
Susanne Mossin 
Sebastian Meier 
Charlotte Held Gotfredsen 
Mathilde H. Lerche 
Niels Chr Nielsen 
Jan Henrik Ardenkjaer-Larsen 

This is the AMPERE MAGNETIC RESONANCE mailing list: 

NMR web database: 

Effect of lanthanide ions on dynamic nuclear polarization enhancement and liquid-state T1 relaxation

Gordon, J.W., S.B. Fain, and I.J. Rowland, Effect of lanthanide ions on dynamic nuclear polarization enhancement and liquid-state T1 relaxation. Magnetic Resonance in Medicine, 2012. 68(6): p. 1949-1954.

In the dynamic nuclear polarization process, microwave irradiation facilitates exchange of polarization from a radical's unpaired electron to nuclear spins at cryogenic temperatures, increasing polarization by >10,000. Doping samples with Gd(3+) ions further increases the achievable solid-state polarization. However, on dissolution, paramagnetic lanthanide metals can be potent relaxation agents, decreasing liquid-state polarization. Here, the effects of lanthanide metals on the solid and liquid-state magnetic properties of [1-(13)C]pyruvate are studied. The results show that in addition to gadolinium, holmium increases not only the achievable polarization but also the rate of polarization. Liquid-state relaxation studies found that unlike gadolinium, holmium minimally affects T(1). Additionally, results reveal that linear contrast agents dissociate in pyruvic acid, greatly reducing liquid-state T(1). Although macrocyclic agents do not readily dissociate, they yield lower solid-state polarization. Results indicate that polarization with free lanthanides and subsequent chelation during dissolution produces the highest polarization enhancement while minimizing liquid-state relaxation.

Jan 28, 2013

Field dependence of T1 for hyperpolarized [1-13C]pyruvate

Chattergoon, N., et al., Field dependence of T1 for hyperpolarized [1-13C]pyruvate. Contrast Media & Molecular Imaging, 2013. 8(1): p. 57-62

In vivo metabolism of hyperpolarized pyruvate has been demonstrated to be an important probe of cellular glycolysis in diseases such as cancer. The usefulness of hyperpolarized (13)C imaging is dependent on the relaxation rates of the (13)C-enriched substrates, which in turn depend on chemical conformation and properties of the dissolution media such as buffer composition, solution pH, temperature and magnetic field. We have measured the magnetic field dependence of the spin-lattice relaxation time of hyperpolarized [1-(13)C]pyruvate using field-cycled relaxometry. [1-(13)C]pyruvate was hyperpolarized using dynamic nuclear polarization and then rapidly thawed and dissolved in a buffered solution to a concentration of 80 mmol l(-1) and a pH of ~7.8. The hyperpolarized liquid was transferred within 8 s to a fast field-cycling relaxometer with a probe tuned for detection of (13)C at a field strength of ~0.75 T. The magnetic field of the relaxometer was rapidly varied between relaxation and acquisition fields where the sample magnetization was periodically measured using a small flip angle. Data were recorded for relaxation fields varying between 0.237 mT and 0.705 T to map the T(1) dispersion of the C-1 of pyruvate. Using similar methods, we also determined the relaxivity of the triarylmethyl radical (OX063; used for dynamic nuclear polarization) on the C-1 of pyruvate at field strengths of 0.001, 0.01, 0.1 and 0.5 T using 0.075, 1.0 and 2.0 mmol l(-1) concentrations of OX063 in the hyperpolarized pyruvate solution.

Jan 25, 2013

Improved Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy through Controlled Incorporation of Deuterated Functional Groups

Zagdoun, A., et al., Improved Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy through Controlled Incorporation of Deuterated Functional Groups. Angew Chem Int Ed Engl, 2013. 52(4): p. 1222-5.

In a spin: The use of deuterated surface passivation agents is shown to restore dynamic nuclear polarization (DNP) surface-enhanced NMR signals that are reduced in substrates containing methyl groups, while still protecting sensitive sites on the surface. Furthermore, apolar groups such as [D(9) ]-trimethylsiloxy (TMS) repel radicals (yellow) away from the surface, thus diminishing detrimental paramagnetic effects induced by radical proximity.

Jan 23, 2013

Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning13C and29Si NMR Enhanced by Dynamic Nuclear Polarization

Lafon, O., et al., Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning13C and29Si NMR Enhanced by Dynamic Nuclear Polarization. The Journal of Physical Chemistry C, 2013: p. 130110124207001.

We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H?1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements εon/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to εon/off ≈ 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

Jan 16, 2013

DNP Spectroscopy to characterize small molecules

The last year has seen a tremendous amount of scientific articles published in the area of Dynamic Nuclear Polarization (DNP) and hyperpolarization in general. There are several articles that demonstrate the large potential of DNP-NMR spectroscopy and I will select a few of them in the coming weeks in a combined post.

Check out these two articles that were published last year (if you haven't done so already):

Lee, D., et al., Enhanced solid-state NMR correlation spectroscopy of quadrupolar nuclei using dynamic nuclear polarization. J Am Chem Soc, 2012. 134(45): p. 18491-4.

Rossini, A.J., et al., Dynamic nuclear polarization NMR spectroscopy of microcrystalline solids. J Am Chem Soc, 2012. 134(40): p. 16899-908.

Both demonstrate the large potential of DNP-NMR spectroscopy to study small molecules with only natural abundance level 13C labels. In both articles 2D 13C-13C correlation spectra of the unlabeled material are shown that would require days of signal averaging without the aid of DNP.

Jan 14, 2013

Jan 11, 2013

Computation of DNP coupling factors of a nitroxide radical in toluene: seamless combination of MD simulations and analytical calculations

Sezer, D., Computation of DNP coupling factors of a nitroxide radical in toluene: seamless combination of MD simulations and analytical calculations. Phys. Chem. Chem. Phys., 2013. 15(2): p. 526-540.

Dynamic nuclear polarization (DNP) employs paramagnetic species to increase the NMR signal of nuclear spins. In liquids, the efficiency of the effect depends on the strength of the interaction between the electron and nuclear spins and the time scales on which this interaction is modulated by the physical motion of the spin-bearing molecules. An approach to quantitatively predict the contribution of molecular motions to the DNP enhancement using molecular dynamics (MD) simulations is developed and illustrated for the nitroxide radical TEMPOL in liquid toluene. A multi-resolution strategy that combines explicit treatment of the solvent at short distances from the free radical with implicit description at large intermolecular distances is adopted. Novel analytical expressions are obtained to correct for the finite spatial extent of the MD simulations. The atomistic and analytical descriptions are sewn seamlessly together by ensuring that for molecular trajectories that start in the near (explicit) region and end in the distant (implicit) region the analytical dipolar spectral densities reproduce the MD estimates. The spectral densities obtained from the developed approach are used to calculate DNP coupling factors separately for the ring and methyl protons of toluene. The agreement with previously reported experimental DNP data at a magnetic field of 3.4 T is noteworthy and encouraging. Maximum obtainable DNP enhancements at other magnetic fields are predicted.

Jan 9, 2013

PhD fellowship / Development of a novel neutron spin filter

The following announcement was just posted on the AMPERE MAGNETIC RESONANCE List:

The following PhD fellowship is currently available at the Paul Scherrer Institute, PSI, Switzerland: 

For the study and the further development of a novel method of DNP and its application in neutron science we are seeking a highly motivated PhD Student 

Your tasks will be to develop a neutron spin filter based on a novel method of dynamic nuclear polarization (DNP) that uses optically excited triplet states in molecular crystals to polarize the nuclei of the filter sample. Various techniques will be used: lasers to excite the short lived triplet states, pulse EPR to characterize them, microwaves to drive the electron-nucleon transitions, NMR to measure the nuclear polarization, cryogenics to cool the sample. You will further study the integration of the spin filter within neutron focusing devices in order to optimize its efficiency for applications in neutron science. The optimization tool will be the Monte-Carlo ray-tracing software McStas. 

You have recently got a university degree in physics with excellent grades and you are a skilful and innovative experimentalist. You preferably have some practical expertise with lasers and/or NMR/EPR spectroscopy or radio frequency techniques in general and enjoy working in a multidisciplinary environment. Some programming skills in C (or comparable programming language) would be beneficial. Team spirit and good communication skills in English and/or German are required. 

Please submit your application online http://www.psi.ch/pa/offenestellen/0429-1

For further information please contact Dr Patrick Hautle (Email: patrick.hautle@psi.ch, phone +41 56 310 32 10) 

The Paul Scherrer Institute, PSI, is with 1500 employees the largest research centre for natural and engineering sciences within Switzerland. We perform world-class research in three main subject areas: Matter and Material; Energy and the Environment; and Human Health. By conducting fundamental and applied research, we work on long-term solutions for major challenges facing society, industry and science. 

Dr. Patrick Hautle

Paul Scherrer Institut
Laboratory for Developments and Methods (LDM) 
CH-5232 Villigen PSI

phone: +41 56 310 3210
fax: +41 56 310 3294

This is the AMPERE MAGNETIC RESONANCE mailing list: 

NMR web database: 

A rapid method for direct detection of metabolic conversion and magnetization exchange with application to hyperpolarized substrates

Larson, P.E., et al., A rapid method for direct detection of metabolic conversion and magnetization exchange with application to hyperpolarized substrates. J. Magn. Reson., 2012. 225(0): p. 71-80.

In this work, we present a new MR spectroscopy approach for directly observing nuclear spins that undergo exchange, metabolic conversion, or, generally, any frequency shift during a mixing time. Unlike conventional approaches to observe these processes, such as exchange spectroscopy (EXSY), this rapid approach requires only a single encoding step and thus is readily applicable to hyperpolarized MR in which the magnetization is not replenished after T(1) decay and RF excitations. This method is based on stimulated-echoes and uses phase-sensitive detection in conjunction with precisely chosen echo times in order to separate spins generated during the mixing time from those present prior to mixing. We are calling the method Metabolic Activity Decomposition Stimulated-echo Acquisition Mode or MAD-STEAM. We have validated this approach as well as applied it in vivo to normal mice and a transgenic prostate cancer mouse model for observing pyruvate-lactate conversion, which has been shown to be elevated in numerous tumor types. In this application, it provides an improved measure of cellular metabolism by separating [1-(13)C]-lactate produced in tissue by metabolic conversion from [1-(13)C]-lactate that has flowed into the tissue or is in the blood. Generally, MAD-STEAM can be applied to any system in which spins undergo a frequency shift.

Solid-State NMR: Biomolecules Viewed at Atomic Resolution

Happy New Year everyone. I hope everyone got a little rest over the Holidays.

For those of you who are members of the American Chemical Society there was a short review-type article about solid-state NMR spectroscopy and how the method advanced over the past 10 years in the December 24th issue of Chemical & Engineering News. Of course DNP is also mentioned in it. Unfortunately the article is not open access but if you are an ACS member you can find it at: