Sep 28, 2020

Stable isotope resolved metabolomics classification of prostate cancer cells using hyperpolarized NMR data #DNPNMR

Frahm, Anne Birk, Pernille Rose Jensen, Jan Henrik Ardenkjær-Larsen, Demet Yigit, and Mathilde Hauge Lerche. “Stable Isotope Resolved Metabolomics Classification of Prostate Cancer Cells Using Hyperpolarized NMR Data.” Journal of Magnetic Resonance 316 (July 2020): 106750.


Metabolic fingerprinting is a strong tool for characterization of biological phenotypes. Classification with machine learning is a critical component in the discrimination of molecular determinants. Cellular activity can be traced using stable isotope labelling of metabolites from which information on cellular pathways may be obtained. Nuclear magnetic resonance (NMR) spectroscopy is, due to its ability to trace labelling in specific atom positions, a method of choice for such metabolic activity measurements. In this study, we used hyperpolarization in the form of dissolution Dynamic Nuclear Polarization (dDNP) NMR to measure signal enhanced isotope labelled metabolites reporting on pathway activity from four different prostate cancer cell lines. The spectra have a high signal-to-noise, with less than 30 signals reporting on 10 metabolic reactions. This allows easy extraction and straightforward interpretation of spectral data. Four metabolite signals selected using a Random Forest algorithm allowed a classification with Support Vector Machines between aggressive and indolent cancer cells with 96.9% accuracy, -corresponding to 31 out of 32 samples. This demonstrates that the information contained in the few features measured with dDNP NMR, is sufficient and robust for performing binary classification based on the metabolic activity of cultured prostate cancer cells.

Sep 25, 2020

Balancing dipolar and exchange coupling in biradicals to maximize cross effect dynamic nuclear polarization #DNPNMR

Equbal, Asif, Kan Tagami, and Songi Han. “Balancing Dipolar and Exchange Coupling in Biradicals to Maximize Cross Effect Dynamic Nuclear Polarization.” Physical Chemistry Chemical Physics 22, no. 24 (2020): 13569–79.


Dynamic nuclear polarization (DNP) by the Cross Eect (CE) has become a game changer for solid-state nuclear magnetic resonance (NMR) spectroscopy. The eciency of CE-DNP depends on the strength of the electron-electron coupling in biradical polarizing agents. Hence, the focus lately has been on designing biradicals with a large net exchange (J) and dipolar (D) coupling. In this study, we reveal that the crucial factor for CE-DNP is not the sum, J+D, but rather the relative magnitude of J and D, expressed as the J/D ratio. We show that the mechanistic basis of this interference lies in the isotropic v.s. the anisotropic nature of the J and D couplings, respectively. This interference can lead to a small (eective) electron-electron coupling for many orientations even when J+D is large, resulting in non-adiabatic rotor-events. We find that when 0< jJ/Dj < 1 the CE-DNP eciency is attenuated for the majority of orientations, with greater attenuation observed at higher magnetic elds and faster Magic-Angle Spinning (MAS) frequency. The interference eect of J and D coupling introduced in this study can explain why many biradicals with high or comparable J + D still show signicantly divergent DNP performances. We debut J/D as a consequential criteria for designing ecient biradicals to robustly perform across a large range of B0 elds and MAS frequencies.

Sep 23, 2020

Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs #DNPNMR #SABRE

Dagys, Laurynas, Barbara Ripka, Markus Leutzsch, Gamal A. I. Moustafa, James Eills, Johannes F. P. Colell, and Malcolm H. Levitt. “Geminal Parahydrogen-Induced Polarization: Accumulating Long-Lived Singlet Order on Methylene Proton Pairs.” Magnetic Resonance 1, no. 2 (August 7, 2020): 175–86.


In the majority of hydrogenative parahydrogen-induced polarization (PHIP) experiments, the hydrogen molecule undergoes pairwise cis addition to an unsaturated precursor to occupy vicinal positions on the product molecule. However, some ruthenium-based hydrogenation catalysts induce geminal hydrogenation, leading to a reaction product in which the two hydrogen atoms are transferred to the same carbon centre, forming a methylene (CH2) group. The singlet order of parahydrogen is substantially retained over the geminal hydrogenation reaction, giving rise to a singlet-hyperpolarized CH2 group. Although the T1 relaxation times of the methylene protons are often short, the singlet order has a long lifetime, provided that singlet–triplet mixing is suppressed, either by chemical equivalence of the protons or by applying a resonant radiofrequency field. The long lifetime of the singlet order enables the accumulation of hyperpolarization during the slow hydrogenation reaction. We introduce a kinetic model for the behaviour of the observed hyperpolarized signals, including both the chemical kinetics and the spin dynamics of the reacting molecules. Our work demonstrates the feasibility of producing singlet-hyperpolarized methylene moieties by parahydrogen-induced polarization. This potentially extends the range of molecular agents which may be generated in a hyperpolarized state by chemical reactions of parahydrogen.

From SharedEPR: New EPR job openings

If you haven't heard of SharedEPR, check it out here: https://sharedepr.org/


Dear SharedEPR community,
There are a series of current job openings related to EPR spectroscopy. See below. Please forward to potentially interested people.

Facility Manager for the Centre for Pulse EPR Spectroscopy (PEPR) at Imperial College London
Closing date: 20 October 2020
Informal enquiries to Dr Maxie Roessler welcome (e-mail m.roessler@imperial.ac.uk)

PhD position (PGR studentship) within the MSCA-ITN-ETN NeuroTrans
Contact: Dr Thomas Stockner, thomas.stockner@meduniwien.ac.at
Closing date: 10 October 2020

Postdoctoral appointee working on transient CW and Pulsed EPR in the Center for Nanoscale Materials and Nanoscience and Technology Division at Argonne National Laboratory
Position is available starting November 2020.
The project aims at investigating the factors influencing spin information and transfer in novel two dimensional structures with well-defined sizes and shapes within supramolecular structures for enhanced emission applications. In these structures, rare earth ions will be caged in well controlled environments consisting of two dimensional networks containing organic linkers whose electronic properties can be tuned by an external stimuli. This electronic tuning will allow the emission of rare earth cations to be turned on or turned off, thereby effectively controlling the optical properties of the supramolecular structure as a whole. This selective adjustment should allow for the potential applications of these structures using rare earth salt mixtures, crude materials of much lower added value than purified rare earth metals. The EPR studies will be complemented with spatially resolved ODMR and synchrotron X-ray STM to understand molecular level of excitations. Depending on the strengths and interests of the successful applicant, the individually designed subproject may be expanded to quantum sensing in nanoscale systems or upconversion nanoparticles. 
We welcome highly motivated candidates with a PhD degree in chemistry or physics. Successful applicants should have a solid background in physical chemistry (spectroscopy), good writing skills and must be able to work independently as part of a team in an interdisciplinary environment. Previous experience in magnetic resonance spectroscopy is required.
For details regarding the application process, salary and possible starting dates please contact Dr. Tijana Rajh (rajh@anl.gov).


Best wishes
The SharedEPR team

Sep 22, 2020

[NMR] Postdoc/PhD position available on high-frequency microwave engineering for NV-diamond NMR

Dear colleagues

a postdoc/PhD/staff position is available in the Bucher lab at the Technical University of Munich in the frame of the EU HORIZON 2020 ERC programme.

Topic: High-frequency microwave engineering for NV-diamond NMR

Description of the work: In recent years, defects in diamonds have been shown to act as atomic-sized sensors for nanoscale nuclear magnetic resonance (NMR) experiments. Here, this innovative quantum technology will be further developed for real-world applications in chemistry, material and life sciences. The project will be highly interdisciplinary at the unique interface between quantum technology and chemistry. The research position is situated in the Chemistry Department (physical chemistry) at the Technischen Universität München and is funded by the European Union. More information can be found on www.bucherlab.org.

Current microscale NV-NMR experiments typically work at low magnetic fields (< 0.1T) which limits their application due to a lack of chemical specificity. In this Postdoc position, a new NV-NMR setup with an increased spectral resolution at higher magnetic fields (0.5-1.5 T) will be developed. Thus, microwave pulses at high power and frequencies (10-40 GHz) will be generated, and a suitable resonator will be designed. The application of this new technique will be in biology and material sciences.

Further information: www.bucherlab.org


Specific Requirements: Prospective candidates should have a Masters/PhD degree in electrical engineering, physics, spectroscopy, or related field, interested in technology development and have extensive hands-on experience in high-frequency microwave engineering. While not required, experience in one or more of the following topics are advantageous: NV-quantum sensing / NMR / EPR spectroscopy

Biomolecular Quantum Sensing

Dr. Dominik Bucher
TUM Junior Fellow
Lichtenbergstr. 4
D-85748 Garching
Tel.: +49 89/28913435

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[NMR] Paramagnetic metal ion DNP | Tutorial by Björn Corzilius| Tuesday, September 29, 8:00am California #DNPNMR

Dear NMR Enthusiast,

The 15th Educational Tutorial will be given by Prof. Björn Corzilius, University of Rostock, Germany, on the topic:

"Paramagnetic metal ions polarizing agents for DNP”.

Abstract:

Paramagnetic metal ions are intriguing alternatives to radical polarizing agents for DNP. In the first part of my presentation I will introduce their magnetic resonance properties and the peculiarities in DNP theory of high-spin metal ion polarizing agents. In the second part I will give an overview of recent DNP applications in biomolecular and materials science using high-spin polarizing agents Mn(II), Fe(III), Cr(III), Gd(III).

Speaker's biography:

2005-2008: PhD, Physical Chemistry, Technical University Darmstadt
2009-2013: Postdoctoral Fellow and Associate, Massachusetts Institute of Technology
2013-2019: Emmy Noether Research Group Leader, Goethe University Frankfurt2019-present: Professor of Physical Chemistry, University of Rostock

Webinar details:
Time: Tuesday, September 29, 2020, 08:00 AM California or 11:00 am Boston or 5:00 PM Paris or 8:30 PM Delhi


Join Meeting: https://ucsb.zoom.us/j/92480496788
Meeting ID: 924 8049 6788

Best regards,

Global NMR Discussion Meetings


[Organizers:
Adrian Draney (Guido Pintacuda Lab, CRMN lyon)
Amrit Venkatesh (Aaron Rossini Lab, Iowa)
Asif Equbal (Songi Han Lab, UCSB)
Blake Wilson (Robert Tycko Lab, NIH)
Michael Hope (Lyndon Emsley Lab, EPFL)
Mona Mohammadi (Alexej Jerschow, NYU)
PinelopiMoutzouri (Lyndon Emsley Lab, EPFL) ]
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Sep 21, 2020

Organic Reaction Monitoring of a Glycine Derivative Using Signal Amplification by Reversible Exchange-Hyperpolarized Benchtop Nuclear Magnetic Resonance Spectroscopy #DNPNMR #SABRE

Chae, Heelim, Sein Min, Hye Jin Jeong, Sung Keon Namgoong, Sangwon Oh, Kiwoong Kim, and Keunhong Jeong. “Organic Reaction Monitoring of a Glycine Derivative Using Signal Amplification by Reversible Exchange-Hyperpolarized Benchtop Nuclear Magnetic Resonance Spectroscopy.” Analytical Chemistry 92, no. 16 (August 18, 2020): 10902–7.


Currently, signal amplification by reversible exchange (SABRE) using para-hydrogen is an attractive method of hyperpolarization for overcoming the sensitivity problems of nuclear magnetic resonance (NMR) spectroscopy. Additionally, SABRE, using the spin order of para-hydrogen, can be applied in reaction monitoring processes for organic chemistry reactions where a small amount of reactant exists. The organic reaction monitoring system created by integrating SABRE and benchtop NMR is the ideal combination for monitoring a reaction and identifying the small amounts of materials in the middle of the reaction. We used a laboratory-built setup, prepared materials by synthesis, and showed that the products obtained by esterification of glycine were also active in SABRE. The products, which were synthesized esterified glycine with nicotinoyl chloride hydrochloride, were observed with a reaction monitoring system. The maximum SABRE enhancement among them (approximately 147-fold) validated the use of this method. This study is the first example of the monitoring of this organic reaction by SABRE and benchtop NMR. It will open new possibilities for applying this system to many other organic reactions and also provide more fruitful future applications such as drug discovery and mechanism study.