Friday, November 30, 2012

HyperSPASM NMR: A new approach to single-shot 2D correlations on DNP-enhanced samples

Donovan, K.J. and L. Frydman, HyperSPASM NMR: A new approach to single-shot 2D correlations on DNP-enhanced samples. J. Magn. Reson., 2012. 225(0): p. 115-119.


Dissolution DNP experiments are limited to a single or at most a few scans, before the non-Boltzmann magnetization has been consumed. This makes it impractical to record 2D NMR data by conventional, t1-incremented schemes. Here a new approach termed HyperSPASM to establish 2D heteronuclear correlations in a single scan is reported, aimed at dealing with this kind of challenge. The HyperSPASM experiment relies on imposing an amplitude-modulation of the data by a single Δt1 indirect-domain evolution time, and subsequently monitoring the imparted encoding on separate echo and anti-echo pathway signals within a single continuous acquisition. This is implemented via the use of alternating, switching, coherence selection gradients. As a result of these manipulations the phase imparted by a heteronucleus over its indirect domain evolution can be accurately extracted, and 2D data unambiguously reconstructed with a single-shot excitation. The nature of this sequence makes the resulting experiment particularly well suited for collecting indirectly-detected HSQC data on hyperpolarized samples. The potential of the ensuing HyperSPASM method is exemplified with natural-abundance hyperpolarized correlations on model systems.

Wednesday, November 28, 2012

Low-temperature cross polarization in view of enhancing dissolution Dynamic Nuclear Polarization in NMR

Jannin, S., et al., Low-temperature cross polarization in view of enhancing dissolution Dynamic Nuclear Polarization in NMR. Chem. Phys. Lett., 2011. 517(4–6): p. 234-236.


Dynamic Nuclear Polarization (DNP) induced by saturation of ESR transitions of TEMPO at 1.2 K and 3.35 T is characterized by build-up rates that are typically 5 times faster for protons than for the carboxylic carbon-13 in acetate. We show that cross polarization from protons to carbon-13 allows one to achieve a polarization P(13C) >20% in less than 10 min, twice as much as has been previously reported, in one-fifth of the time. This should open the way to an unprecedented improvement in the efficiency of dissolution DNP.

Monday, November 26, 2012

High field dynamic nuclear polarization at 6.7T: Carbon-13 polarization above 70% within 20 min

Jannin, S., et al., High field dynamic nuclear polarization at 6.7&T: Carbon-13 polarization above 70% within 20 min. Chem. Phys. Lett., 2012. 549(0): p. 99-102.


In most applications of dissolution-DNP, the polarization of nuclei with low gyromagnetic ratios such as 13C is enhanced directly by irradiating the ESR transitions of radicals with narrow ESR lines such as Trityl at low temperatures T = 1.2 K in polarizing fields B0 ⩽ 5 T. In a field B0 = 6.7 T at T = 1.2 K, DNP with TEMPO leads to a rapid build-up of proton polarization P(1H) = 91% with τDNP(1H) = 150 s. CP at low temperatures yields a polarization P(1H → 13C) in excess of 70% within 20 min. After rapid dissolution to room temperature, this is 122 000 times larger than the Boltzmann polarization at 300 K and 6.7 T.



Friday, November 23, 2012

Dissolution dynamic nuclear polarization efficiency enhanced by Hartmann–Hahn cross polarization

Batel, M., et al., Dissolution dynamic nuclear polarization efficiency enhanced by Hartmann–Hahn cross polarization. Chem. Phys. Lett., 2012. 554(0): p. 72-76.


Dynamic nuclear polarization (DNP) can be used to increase the polarization of nuclei by utilizing the higher electron polarization. Typically, in dissolution DNP heteronuclei are directly polarized due to their longer relaxation times. We present the combination of DNP to protons with subsequent cross polarization to 13C followed by dissolution to solution state. The experiment was implemented using a modified dissolution DNP probe. For a [13C]urea sample doped with TEMPO the carbon polarization and its build-up rate could be increased by a factor of two using CP. With small losses, this gain could be transferred to the solution by dissolution.



Wednesday, November 21, 2012

Rapid Natural-Abundance 2D (13) C-(13) C Correlation Spectroscopy Using Dynamic Nuclear Polarization Enhanced Solid-State NMR and Matrix-Free Sample Preparation

Takahashi, H., et al., Rapid Natural-Abundance 2D (13) C-(13) C Correlation Spectroscopy Using Dynamic Nuclear Polarization Enhanced Solid-State NMR and Matrix-Free Sample Preparation. Angew Chem Int Ed Engl, 2012. 51(47): p. n/a-n/a.4


Ultra-fast: Substantial solid-state NMR sensitivity can be achieved using dynamic nuclear polarization and matrix-free sample preparation (that is, absence of solvent and cryoprotectant). This method avoids line-broadening, maximizes sample filling factor, and allows natural-abundance 2D (13) C-(13) C dipolar correlation experiments to be carried out in tens of minutes. MW=microwaves.

Monday, November 19, 2012

The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy

Lumata, L.L., et al., The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy. RSC Advances, 2012.


The free radical 2,2-diphenyl-1-pycrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for 13C, 15N, 89Y, and 109Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.



Friday, November 16, 2012

Enhanced Solid-State NMR Correlation Spectroscopy of Quadrupolar Nuclei Using Dynamic Nuclear Polarization

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. 18491-18494.


By means of a true sensitivity enhancement for a solid-state NMR spectroscopy (SSNMR) experiment performed under dynamic nuclear polarization (DNP) conditions, corresponding to 4-5 orders of magnitude of time savings compared with a conventional SSNMR experiment, it is shown that it is possible to record interface-selective (27)Al-(27)Al two-dimensional dipolar correlation spectra on mesoporous alumina, an advanced material with potential industrial applications. The low efficiency of cross-polarization and dipolar recoupling for quadrupolar nuclei is completely negated using this technique. The important presence of pentacoordinated Al has not only been observed, but its role in bridging interfacial tetra- and hexacoordinated Al has been determined. Such structural information, collected at low temperature ( approximately 103 K) and 9.4 T with the use of DNP, would have been impossible to obtain under standard conditions, even using a higher magnetic field. However, here it is demonstrated that this information can be obtained in only 4 h. This work clearly opens a new avenue for the application of SSNMR to quadrupolar nuclei and notably the atomic-scale structure determination of catalysis materials such as mesoporous alumina.

Wednesday, November 14, 2012

Postdoc position in biomolecular solid state NMR at NIH


I expect to have an opening for a new postdoctoral fellow in my research group on the NIH campus in Bethesda, Maryland, starting in mid-2013. Research will focus on structural studies of supramolecular assemblies related to HIV-1 maturation, using solid state NMR, electron microscopy, DNP, etc. Extensive prior experience with protein expression, purification, and labeling is a requirement for this position (because this project depends heavily on non-standard sample preparation). Previous experience with solid state NMR methods is desirable, but not necessary. To apply, please send your CV, a description of your recent research activities, and the names of three references to robertty@mail.nih.gov


Dr. Robert Tycko 
Laboratory of Chemical Physics, NIDDK 
Building 5, Room 112 
National Institutes of Health 
Bethesda, MD 20892-0520 
301-402-8272 (office); 301-402-4687 (lab) 

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Monday, November 12, 2012

Do you miss an article?

Every now and then I have received emails from blog readers bringing articles about DNP-NMR spectroscopy to my attention that I have simply missed. Please keep doing that!

I'm scanning the tables of content of all major publications, but sometimes I just miss an article. Also, sometimes a reference gets lost when I import the bibliographic information in my article library and forget to post it on the blog. Normally I wait until an article is published with all bibliographic information (volume number, page numbers etc.), so if an article is 'in press' or 'just accepted' it sometimes takes a few days/weeks until I post it on here.

However, if you think I missed an article (or any other DNP-NMR related information that you would like to see on here), please, do not hesitate to contact me and let me know what you are missing.

Cheers,
Thorsten

Friday, November 9, 2012

Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14T and 30K

Matsuki, Y., et al., Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14T and 30K. J. Magn. Reson., 2012. 225(0): p. 1-9.


We describe a 1H polarization enhancement via dynamic nuclear polarization (DNP) at very low sample temperature T ≈ 30 K under magic-angle spinning (MAS) conditions for sensitivity-enhanced solid-state NMR measurement. Experiments were conducted at a high external field strength of 14.1 T. For MAS DNP experiments at T ≪ 90 K, a new probe system using cold helium gas for both sample-cooling and -spinning was developed. The novel system can sustain a low sample temperature between 30 and 90 K for a period of time >10 h under MAS at νR ≈ 3 kHz with liquid He consumption of ≈6 L/h. As a microwave source, we employed a high-power, continuously frequency-tunable gyrotron. At T ≈ 34 K, 1H DNP enhancement factors of 47 and 23 were observed with and without MAS, respectively. On the basis of these observations, a discussion on the total NMR sensitivity that takes into account the effect of sample temperature and external field strength used in DNP experiments is presented. It was determined that the use of low sample temperature and high external field is generally rewarding for the total sensitivity, in spite of the slower polarization buildup at lower temperature and lower DNP efficiency at higher field. These findings highlight the potential of the current continuous-wave DNP technique also at very high field conditions suitable to analyze large and complex systems, such as biological macromolecules.

Wednesday, November 7, 2012

First Announcement: EUROMAR 2013



Dear Colleagues, 

On behalf of the Organizing Committee, it is my pleasure to invite you to EUROMAR 2013, the 9th European Magnetic Resonance Conference that will be organized on the island of Crete/Greece, by the National Center for Scientific Research “Demokritos”. 

The conference will take place between 30th June to 5th July at the Creta Maris Convention Center, a modern facility situated 25 km from the Heraklion International Airport and adjacent to the town of Hersonissos. 

EUROMAR 2013 will bring together distinguished scientists of the magnetic Resonance field in the unique location of Crete that combines Mediterranean landscape with world-renowned historical sites and a rich cultural heritage. The conference will cover all aspects of Magnetic Resonance theory, methodology and applications. The 5-day scientific program will run in three parallel sessions and will be structured around lectures of distinguished invited speakers and oral presentations of selected high-quality abstracts. 

Representative topics include: 

Biosolids, Theory and Computation, Liquid State NMR Methods, Materials and Processes, Transport and Diffusion, Proteins and Nucleic Acids, Metabolomics, Imaging, in Cell and in Vivo studies, Paramagnetic Systems, EPR Methods and Applications, Solid State NMR Methods, Relaxation and Dynamics, Sensitivity Enhancement, Small Molecules and Pharmaceuticals, New Methodologies and Instrumentation Advances, Solid State Physics, Industrial and Cultural Applications. 

Confirmed plenary speakers include: 

Anja Boeckmann (Institute of Biology and Chemistry of Proteins, France) 
Dmitri Budker (University of California Berkeley, U.S.A.) 
Isabella Felli (University of Florence, Italy) 
Daniella Goldfarb (Weizmann Institute of Science, Israel) 
Stephen Hill (NHMFL/ Florida State University, U.S.A.) 
Arno Kentgens (Radbour University, The Netherlands) 
Dominique Massiot (CEMHTI-CNRS, France) 
Alex Pines (University of California Berkeley, U.S.A.) 
Graham Smith (University of St Andrews, United Kingdom) 
Yi-Qiao Song (Schlumberger-Doll Research, U.S.A) 
Shimon Vega (Weizmann Institute of Science, Israel) 
Peter van Zijl (Kennedy Krieger Institute, U.S.A.) 
Charalampos (Babis) Calodimos (Rutgers University, U.S.A.) 

Key dates: 

Conference Registration Opens 01/12/2012 
Early Registration Closes 01/04/2013 
Deadline for Oral Submission 01/05/2013 
Deadline for Poster Submission 31/05/2013 

Website: 

The website of the conference is http://www.euromar2013.org/index.html and is being constantly enriched with the necessary information on the conference, the venues and traveling to Crete. 

I believe that the attractive setting of Crete together with EUROMAR’s high scientific level will provide an excellent forum for rewarding discussions and exchanges between magnetic resonance researchers from around the world. 

Looking forward to welcoming you in Crete, 

Georgios Papavassiliou 
Chairman 
EUROMAR 2013 Conference 

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Monday, November 5, 2012

The 3rd U.S.-Canada Winter School on Biomolecular Solid-State NMR Stowe, Vermont, January 6-11, 2013

The 3rd U.S.-Canada Winter School on Biomolecular Solid-State NMR 
Stowe, Vermont, January 6-11, 2013 

Organizers: Mei Hong (Iowa State), Chad Rienstra (UIUC), and Bob Griffin (MIT) 

Dear colleagues, 

We invite you to encourage your students, postdocs, and associates to attend the 3rd Winter School on Biomolecular Solid-State NMR, to be held on Jan 6-11, 2013, in Stowe, Vermont. Similar to the two previous, very successful, Winter Schools, this pedagogical meeting, unique in North America, is aimed at students and postdocs in the field of biological solid-state NMR, as well as more senior scientists in related fields who are interested in entering this vibrant field. Our goals are to foster the scientific development of the next generation of North American biological solid-state NMR spectroscopists and to encourage information sharing and collaborations among research groups. Topics in the 3rd Winter School include: 

· Basics of solid-state NMR: orientation dependence, density operators, average Hamiltonian theory, dipolar and CSA recoupling 
· Multidimensional correlation techniques: resonance assignment and structure determination 
· Theory of polarization transfer and dipolar decoupling 
· Pushing the sensitivity envelope: dynamic nuclear polarization 
· Solid-state NMR techniques for measuring distances, torsion angles, dynamics and orientations of diamagnetic and paramagnetic systems, for both spin-1/2 and quadrupolar nuclei 
· Beating the 800-pound gorilla: NMR of membrane-bound proteins 
· Devil in the details: methods for protein expression, isotopic labeling, and preparation of MAS and oriented-membrane samples 
· Numerical simulations and structure calculation methods 
· NMR probe design. 

Lectures and problem-solving sessions will be held in the mornings, late afternoons, and evenings, with time for recreation in the early afternoon. 

Speakers: The following people have agreed to give lectures: 

Tim Cross (Florida State) 
Matthias Ernst (ETH) 
Phil Grandinetti (Ohio State) 
Bob Griffin (MIT) 
Mei Hong (Iowa State) 
Yoshitaka Ishii (U Illinois Chicago) 
Chris Jaroniec (Ohio State) 
Ann McDermott (Columbia) 
Stanley Opella (UCSD) 
Chad Rienstra (UIUC) 
Klaus Schmidt-Rohr (Iowa State) 
Robert Tycko (NIH) 
Kurt Zilm (Yale) 

Venue and transportation: The meeting will be held at the Inn at the Mountain in Stowe, http://www.stowe.com/plan/groups/stowe-mountain-resort-the-inn-at-the-mountain/. Stowe is easily accessible from airports in Burlington, VT, Manchester, NH, and Boston, MA. 

Cost: Room and board will be free for attendees. The registration fee is $325 for academic attendees and $600 for industrial attendees. We anticipate space for about 75-80 people. 

Application: Interested students and postdocs should send the following application material as PDF attachments to mhong@iastate.edu <mhong@iastate.edu

1. CV and publication list (for the purpose of room assignment, please indicate your gender in the CV) 
2. A one-page description of the current research 
3. A one-page letter of recommendation from the current research advisor. 

(In the case of a senior scientist, a brief explanation of your motivations can substitute for a letter of recommendation.)

Postdoctoral Position in DNP Development

Postdoctoral Position for developing new spectroscopic methods in DNP NMR 


A postdoctoral position is available immediately at the U.S. National High Magnetic Field Lab (NHMFL) in Tallahassee, FL, for developing new DNP techniques to enable liquid state NMR spectroscopy with a focus on high resolution NMR studies at high fields. This project builds on recent developments in Gyrotron sources and shuttling DNP systems to produce highly polarized small molecules for NMR characterizations. 

Interested candidates should have a strong background in one or more of the following areas: NMR sample shuttling and solution NMR spectroscopy, development and application of new NMR hardware and methods, NMR in super-critical fluids, dynamic nuclear polarization, millimeter-wave and high-frequency EPR hardware development. 

This project is an NSF MRI-funded partnership between the NMR and EMR groups at the NHMFL to develop a new platform for DNP-enhanced NMR spectroscopy to enable solution NMR characterization of sensitivity-limited samples. This endeavor leverages collaborative efforts between the groups of Steve Hill and Bill Brey at Florida State University, Joanna R. Long at the University of Florida and Lucio Frydman at the Weizmann Institute and Florida State University and is part of a NHMFL initiative to develop a user program in DNP, which includes projects to offer dissolution DNP at the University of Florida and MAS DNP and Overhauser DNP at Florida State University. The position is available immediately, and interested candidates should send their CV's, including letters from three references, to Prof. Steve Hill (shill@magnet.fsu.edu). 


Florida State University is an Affirmative Action/Equal Opportunity employer 
and solicits applications from women and under-represented minorities. 

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Friday, November 2, 2012

The theory and practice of hyperpolarization in magnetic resonance using parahydrogen


Green, R.A., et al., The theory and practice of hyperpolarization in magnetic resonance using parahydrogen. Prog Nucl Magn Reson Spectrosc, 2012. 67(0): p. 1-48.


Unfortunately there is currently no abstract available.

Thursday, November 1, 2012

Postdoctoral Positions in DNP


As part of a new initiative at the U.S. National High Magnetic Field Laboratory, several postdoctoral positions are available. Our goals are two-fold: 1) to develop a user facility where external users can collect DNP data and 2) to develop DNP technologies in concert with others in the field, with a particular focus on high magnetic fields/frequencies. 

I would appreciate it if you could pass on this email to anyone potentially interested in these positions. Details can be found in the attached position descriptions. I apologize if you have received more than one email regarding these positions. 



Sincerely, 
Joanna 



Joanna R. Long 
Assoc. Professor of Biochemistry & Molecular Biology 
Director, Advanced Magnetic Resonance Imaging and Spectroscopy Facility 
National High Magnetic Field Laboratory 
McKnight Brain Institute, LG-187 
University of Florida 
Box 100245 
Gainesville, FL 32610-0245 
(352)846-1506 – Telephone 
(352)392-3422 – Fax