Session PE. There are 39 abstracts in this session.

Session: HYPERPOLARIZATION, poster number: 228

Characterization of SABRE and SABRE-SHEATH in Complex Spin Systems: Biomolecules, Dual-Modality Agents, and Cleavable Double Agents

Miranda Limbach1; Thomas Gebhardt1; Ishani Senanayake1; Max Gemeinhardt1; Eduard Chekmenev2, 3; Yuqing Hou1; Boyd Goodson1
1Southern Illinois University, Carbondale, IL; 2Wayne State University, Karmanos Cancer Institute, Detroit, MI; 3Russian Academy of Sciences, Moscow , Russia
SABRE is fast, inexpensive, easily scalable, and does not require major instrumentation. However, while great progress has been made over a relatively short time, SABRE is still limited in terms of the scope of substrates. Here we are concerned with attempting SABRE in relatively large, complex spin systems, with the goals of adding to the SABRE-active substrate classes and creating complex hyperpolarized spin networks for studying fundamental spin physics. We are investigating a number of different systems, including large biomolecules like cytidine; dual-modality agents; and multi-spin-label variants of our cleavable “double agents” that can yield two different SABRE agents following hyperpolarization and hydrolytic cleavage. Ongoing efforts include the population, characterization, and lifetime measurement of long-lived spin states.

Session: HYPERPOLARIZATION, poster number: 229

Exploring Pyruvate Analogues as Non-persistent Endogenous Radical Precursors for Dissolution DNP

Claudia Zanella1; Andrea Capozzi1; Hikari AI Yoshihara1; Rolf Gruetter1; Jessica AM Bastiaansen2, 3
1EPFL, LIFMET, Lausanne, Switzerland; 2UNIL, RAD, Lausanne, Switzerland; 3CHUV, RAD, Lausanne, Switzerland

Dissolution DNP requires paramagnetic species for hyperpolarizing nuclei. Their presence shortens the nuclear relaxation time after dissolution and they must be removed for clinical applications, which is time-consuming. Non-persistent radicals can be generated by UV irradiation and conveniently quench during dissolution. We studied two novel and endogenous radical precursors, alpha-ketobutyrate (αkB) and alpha-ketovalerate (αkV). They both generated free radicals upon UV irradiation. Adding glucose to the matrix considerably decreased the radical yield of αkV and αkB compared to PA, and αkV needed a ~3.5x higher concentration than PA to generate the same target radical level. Both endogenous precursors αkV and αkB generated a sufficiently high yield of non-persistent radicals to be used as radical precursors in DNP samples.

Session: HYPERPOLARIZATION, poster number: 230

Extending the Substrate Scope of SABRE to Antifungal Drugs

Keilian Macculloch; Evan Akeroyd; Patrick Tomhon; Sören Lehmkuhl; Thomas Theis
NCSU, Raleigh, NC

SABRE (Signal amplification by reversible exchange) is a robust and inexpensive way to enhance MR signals using parahydrogen. With this relatively new technique, already quite a few common drugs and metabolites have been successfully polarized. Here, we add the polarization of various antifungal drugs to this list and provide mechanistic and kinetic insights into the hyperpolarization process. We optimized the polarization with respect to temperature and polarization transfer field. Additionally, we determined exchange rates of different functional groups binding to the SABRE catalyst using EXSY. In conclusion this work broadens the SABRE substrate scope and is geared toward biomedical applications of hyperpolarized MRI contrast agents.

Session: HYPERPOLARIZATION, poster number: 231

Can hyperpolarized micro to milli-T NMR compete with standard multi-T NMR?

Patrick Tomhon1; Evan Akeroyd1; Austin Browning1; Sören Lehmkuhl1; Stephan Appelt2; Matthew Rosen3; Yi-Fen Yen3; Eduard Chekmenev4; Thomas Theis1
1NC State University, Raleigh, NC; 2Forschungszentrum Jülich, Juelich, Germany; 3MGH/A.A. Martinos Center, Boston, MA; 4Wayne State University, Detroit, MI

Most of NMR trends towards ever higher magnetic fields because polarization, inductive detection and chemical shift dispersion increase with B0. Here we ask the question: “Can the full analytical power of NMR be unleashed without high magnetic fields of large superconducting magnets?” To make this a reality, polarization has to be produced independent of a strong B0, detection has to be sensitive at low frequencies, and precise chemical information has to be extractable from low-field spectra. We present recent progress in  these three aspects. Specifically, parahydrogen hyperpolarization techniques are generalized and combined with unconventional NMR detection modes to give information rich and highly resolved NMR spectra. 

Session: HYPERPOLARIZATION, poster number: 232

Developing Methods for Efficient Removal of Homogeneous Catalysts from Solutions with SABRE and PHIP-Hyperpolarized Molecules

Max Gemeinhardt1; Drew Brittin1; Kenneth Ko2; Miranda Limbach1; Thomas Gebhardt1; Eduard Chekmenev3, 4; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2University Of Miami, Coral Gables , Fl; 3Wayne State University, Karmanos Cancer Institute, Detroit , Mi; 4Russian Academy Of Science, Moscow, Russia
The low detection sensitivity of NMR/MRI has led to growing interest in improving the signal by hyperpolarization. In particular, parahydrogen-based hyperpolarization methods like SABRE and PHIP are of interest because they are fast, cheap, scalable, and do not require major instrumentation / infrastructure. However, the dependence of these methods on metal catalysts necessitates rapid catalyst separation from the resulting hyperpolarized agents to enable SABRE/PHIP in clinical settings or for many other biological applications. We describe current efforts that utilize surface-functionalized beads to efficiently remove SABRE or PHIP catalysts from hyperpolarized solutions (where SABRE efforts center around the hyperpolarization and separation of hyperpolarized 15N2-imidazole and bead characterization by AA and EDX), and general strategies that may aid in furthering this field.

Session: HYPERPOLARIZATION, poster number: 233

13C dDNP with SA-BDPA at 6.7T and 1.1K: an ideal system to discriminate transfer of Zeeman energy from dipolar energy

Alice Radaelli1; Andrea Capozzi1, 2; Emine Can3; Hiroshi Nonaka4; Shinsuke Sando4; Arnaud Comment5; Jan Henrik Ardenkjær-Larsen2; Rolf Gruetter1; Hikari Yoshihara1
1LIFMET, EPFL, Lausanne, Switzerland; 2Department of Health Technology, DTU, Kgs. Lyngby, Denmark; 3Calico Life Sciences LLC, South San Francisco, CA; 4The University of Tokyo, Tokyo, Japan; 5General Electric Healthcare, Chalfont St Giles, United Kingdom

SA-BDPA is a water-soluble, narrow-linewidth radical whose DNP properties have only been studied in MAS-DNP conditions. Here, we report LOD-ESR and 13C DNP measurements on a 13C urea sample doped with SA-BDPA at 6.7 T, 1.1 K. We observed that, because of the very narrow ESR line of the radical, it was possible to identify two different mechanisms leading to the DNP enhancement: pure thermal mixing, where the enhancement is solely due to the transfer of electronic dipolar energy, and solid effect. Moreover, the polarization levels and rates on such sample were found to be comparable to those obtained with trityl.

Session: HYPERPOLARIZATION, poster number: 234

Investigation of calcium carbonate nucleation at mM concentration via dissolution dynamic nuclear polarisation

Gabriele Stevanato1; Martins Balodis1; Brad Chmelka2; Lyndon Emsley1
1EPFL, Lausanne, Switzerland; 2UCSB, Santa Barbara, CA

We apply dissolution dynamic nuclear polarisation (dDNP) to investigate the early stage solution-state nucleation process of CaCO3 at low concentration (~mM range), room temperature and different pH

Session: Hyperpolarization / Small Molecules, poster number: 235

J-Resolved ODNP Enhanced Proton NMR Spectroscopy at Low Magnetic Fields

Timothy Keller; Thorsten Maly
Bridge12 Technologies, Inc., Framingham, MA

The main challenges associated with low-field NMR spectroscopy are limited sensitivity and resolution. In liquids at low magnetic fields, Overhauser dynamic nuclear polarization (ODNP) is among the most promising methods for enhancing signal sensitivity. In this work, we demonstrate high-resolution ODNP enhanced proton NMR spectroscopy at low magnetic fields (0.35 T, 14.5 MHz). With standard shimming methods, we obtain a linewidth of 3.9 Hz (0.27 ppm) for the methyl peak in toluene. This high chemical shift resolution allows us to characterize microwave induced sample heating with the NMR thermometer ethylene glycol. At low magnetic fields, the resolution can be further improved by the introduction of 2D NMR experiments. This is demonstrated with J-resolve on ethyl crotonate.

Session: HYPERPOLARIZATION, poster number: 236

Searching for axion dark matter with hyperpolarized samples

Xiaoqing Li
Duke University Department of Physics, Durham, NC

The existence of dark matter is controversial. Many astrophysical phenomena cannot be explained without the gravitational impact of dark matter, but the direct detection of dark matter has not succeeded. CASPEr experiment is a new method to detect the nongravitational interaction between dark matter and nuclear spins with NMR techniques. Due to the low sensitivity of the CASPEr experiment, we need a huge amount of a hyperpolarized NMR sample. A scalable hyperpolarization method, SABRE, is what we think the best way to fulfill this task. To achieve much higher polarization, we proposed two methods – high-pressure SABRE which promotes high para-hydrogen solubility and pulse SABRE which could effectively adjust the couplings between hydrides and target nuclei in the SABRE complex.  

Session: HYPERPOLARIZATION, poster number: 237

Synthesis of Olefin Isotopomers by Heterogeneous Catalysis Analyzed via Nuclear Magnetic Resonance Spectroscopy

Maria-Jose Ferrer1; Qiuying Li1; Diana Choi1; Tommy Y. Zhao1; Minda Chen2; Wenyu Huang2; Clifford R. Bowers1
1University of Florida, Gainesville, FL; 2Iowa State University and Ames Laboratory, Ames, IA

In addition to biomedical applications, Parahydrogen Enhanced Polarization (PEP) is a inexpensive technique for characterizing mechanisms of hydrogenation catalysis. However, adducts or intermediates formed by pairwise parahydrogen addition into magnetically equivalent sites are NMR silent.  Alternatively, hydrogenation with D2 gas can reveal mechanistic information, yielding products that are detectable by NMR via isotope shifts.  Indeed, much about the mechanisms of hydrogenation catalysis of alkenes over supported metals like Rh, Pt and Pd comes from deuterium studies, and this has implications for PEP. Using heterogeneous catalysis with H2/D2 mixtures, we investigated the distribution of deuterium in the gaseous products using the isotope chemical shifts. The implications for long-lived states and pairwise addition mechanisms are discussed, and preliminary results will be presented.

Session: HYPERPOLARIZATION, poster number: 238

A Complete Study of Metronidazole Hyperpolarization with SABRE using Automated Pneumatic Shuttling

Patrick Tomhon1; Sören Lehmkuhl1; Evan Akeroyd1; Christopher Parish1; Eduard Chekmenev3; Thomas Theis1, 2
1North Carolina State University, Raleigh, NC; 2UNC/NCSU Joint Department of Biomed. Engineering, Raleigh, NC; 3Wayne State University, Detroit, MI

Signal Amplification By Reversible Exchange (SABRE) is a parahydrogen based hyperpolarization methodology that is simple, fast, and robust.  Metronidazole is a promising target in the progress toward ­in vivo imaging with SABRE hyperpolarized biotracers (drugs and metabolites) due to its high polarization (~20%) and long relaxation times (~8 min). Using self-designed synchronized and automated pneumatic shuttling, we present a complete study providing novel insights into the metronidazole hyperpolarization mechanism with SABRE. Specifically, we elucidate the spin dynamics of the heteronuclear pseudo-singlet, demonstrate binding mechanisms in the SABRE chemical process with hyperpolarized multidimensional NMR, and show detection of the long-lived 15N polarization on protons.

Session: HYPERPOLARIZATION, poster number: 239

SLIC-based Sensing And Polarization Transfer In Parahydrogen Induced Polarization

Nuwandi M. Ariyasingha; Eduard Y. Chekmenev
Wayne state university, Detroit, MI

Polarization transfer from hyperpolarized hydrides to 15N or 19F heteronucleus using SABRE and QUASi Resonance (QUASR) SABRE process has been studied at 0.0475 T for different types of molecules using triangular Spin-Lock Induced Crossing (SLIC) rf pulse. Magnetization along z-axis was created for 15N or 19F spin sites in exchangeable substrates as a result. SLIC rf pulse was also employed at 0.0475 T magnetic field to study relaxation dynamics of the long-lived spin states (LLSS) of hyperpolarized propane gas produced via heterogeneous hydrogenation reaction of propylene. We also demonstrate the feasibility of TLLSS relaxation measurements using SLIC sensing via a “partial” SLIC experiments and demonstrate the utility of this approach in the relaxation studies of liquefied HP propane

Session: HYPERPOLARIZATION, poster number: 240

Hyperpolarization of Sterically Hindered Ortho-Substituted Pyridine and Pyrimidine Moieties by SABRE

Ratnamala Mandal; Pierce Pham; Christian Hilty
Texas A&M University, College Station, TX


Ortho-substituted N-heterocycles, which are ubiquitous in nature, are not well polarized by the Signal Amplification by Reversible Exchange (SABRE) technique using Ir-NHC catalysts with IMes ligands. Here, allylamine is used as an additive to the SABRE reaction mixture to overcome the problem of hindered binding for these substrates. The presence of allylamine dramatically increased the polarization of an ortho-substituted pyrimidine moiety present in biological molecules, 2,4-diaminopyrimidine. The effect of coligand addition was characterized and the enhancement value was observed to be influenced by the nature of the substituent present in the ortho-position of the molecule.

Session: HYPERPOLARIZATION, poster number: 241

Ligand-receptor binding experiment using long-lived state in a four-spin system hyperpolarized at room temperature

Koichiro Miyanishi
Osaka University, Toyonaka-shi, Japan

We have demonstrated the encoding of a four-spin system hyperpolarized at room temperature into a  long-lived state and its application for ligand-receptor binding experiment. The polarization of the aromatic protons in p-chlorobenzoic acid (PCBA) was increased by using dissolution triplet-DNP at room temperature, and the protons were encoded into a long-lived state. As an application of the hyperpolarized long-lived state, we performed ligand-receptor (b-cyclodextrin(bCD)/PCBA) binding experiments and assessed the performance of hyperpolarized PCBA as a sensor for the binding.

Session: HYPERPOLARIZATION, poster number: 242

Introduction of a water-soluble triradical dopant for low-temperature DNP and its application to time-resolved DNP-NMR on Calmodulin complex formation

Jaekyun Jeon; Wai-Ming Yau; Robert Tycko
National Institutes of Health, Bethesda, MD

The cross-effect DNP mechanism is based on the three-spin (e-e-n) transition, in which EPR frequency difference between two paramagnetic electron spins to be greater than the NMR frequency. While nitroxide-based biradicals are widely used, previously we introduced triradical dopants, various derivatives of DOTOPA. However, the solubility has been a limitation, causing variations between samples in terms of enhancement and DNP build-up times. In this poster presentation, we will introduce a water-soluble DOTOPA derivative, succinyl-DOTOPA. We will discuss the DNP properties of succinyl-DOTOPA and compare it with the commercially available biradical, AMUPol. In addition, the recent application of the triradical dopant to our time-resolved solid-state NMR study will be presented.

Session: HYPERPOLARIZATION, poster number: 243

Enhanced Nuclear-Spin Hyperpolarization of Amino Acids and Proteins via a Reductive Radical Quencher

Hanming Yang; Miranda Mecha; Collin Goebel; Silvia Cavagnero
University of Wisconsin-Madison, Madison, WI

13C hyperpolarization via low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) enables remarkable sensitivity enhancements for the detection of aromatic amino acids and proteins in solution. Prolonged optical irradiation of NMR samples, however, leads to some photodegradation, limiting very-long-term data collection. Here, we show that addition of trace amounts of ascorbic acid (vitamin C, VC) significantly slows down degradative processes. The VC additive enhances LC-photo-CIDNP S/N, and is particularly effective upon long-term data collection (2.3-fold at 256 scans). We propose that VC operates by quenching Trp radical intermediates, thus outcompeting degradative processes involving the Trp radical cation. Remarkably, the VC advantage also applies to proteins, leading to 60% S/N increases at 2048 scans and suggesting future opportunities to perform ≥3D LC-photo-CIDNP.

Session: HYPERPOLARIZATION, poster number: 244

Optimizing nitroxide biradicals for cross-effect MAS-DNP: the role of g-tensors’ distance

Frederic Mentink-Vigier1; Thomas Halbritter2; Johan van Tol3; Snorri Sigurðsson2
1NHMFL, CIMAR, Tallahassee, FL; 2University of Iceland, Reykjavík,, IS; 3NHMFL, EMR, Florida State University, Tallahassee, FL

MAS-DNP is a powerful method to increase the sensitivity of solid-state NMR experiments, and bis-nitroxides are often used to boost the signals via the cross-effect (CE) mechanism. The biradical structures underwent extensive optimization to improve their performance focusing, in part, on the role of the nitroxides’ g-tensors relative orientation (alpha, beta, gamma). The role of the beta angle was clearly identified experimentally and theoretically. Nonetheless previous approaches are incomplete and the question “Can bis-nitroxide be improved?” is still debatable. Here, we demonstrate that the g-tensor’s distance, is sufficient to evaluate the potential performance of a bis-nitroxide structure, for moderate electron-electron coupling. This is illustrated theoretically and experimentally on the bTurea series, AMUPol, bcTol and bcTol-M.

Session: HYPERPOLARIZATION, poster number: 245

Real-time Monitoring of In Vivo Free Radical Scavengers through Hyperpolarized [1-13C] N-acetyl Cysteine in Human Pancreatic Tumor Xenografts

Kazutoshi Yamamoto1; Ana Opina2; Keita Saito1; Ronja Malinowski3; Tomohiro Seki1; Nobu Oshima1; Nobu Oshima1; Deepak Sail2; Shun Kishimoto1; Jeffrey Brender1; Nallathamby Devasahayam1; Jan H. Ardenkjær-Larsen3; James Mitchell1; Murali Krishna1
1National Institutes of Health, NCI, Bethesda, MD; 2Imaging Probe Development Center, NIH, Rockville, MD; 3Technical University of Denmark, Lyngby, Denmark

Despite recent technological advances in NMR, its poor sensitivity continues to be a primary limitation particularly for real-time in vivo metabolic MRS studies.  Here, we synthesized and demonstrated [1-13C] N-acetyl cysteine as a promising novel probe for hyperpolarized 13C MRI, which has a major bottleneck for available number of probes.  NAC is a widely used therapeutic to stimulate glutathione synthesis, which plays a central role in a wide variety of biological functions, including the synthesis of proteins, DNA, transport, enzyme activities, metabolism, and protection of cells. Glutathione elevates detoxification and works directly as a free radical scavenger.  In vivo chemical conversions were observed in human pancreatic tumor xenografts, which provided insights into redox status, metabolic profile, and enzymatic activities.

Session: HYPERPOLARIZATION, poster number: 246

Imaging the Metabolic Evolution of Glioblastoma throughout Tumor Progression to the Point of Relapse

Travis Salzillo1, 2; Joy Gumin1; Jaehyuk Lee1; Niki Zacharias1; Frederick Lang1, 2; Pratip Bhattacharya1, 2
1MD Anderson Cancer Center, Houston, TX; 2MD Anderson Cancer Center UTHealth Graduate School, Houston, TX

Glioblastoma is an aggressive brain cancer with a median survival of only 15 months despite standard-of-care treatment. Outcomes may be improved if the disease can be identified earlier in progression and if treatment can be rapidly assessed for efficacy. This project compared conventional T2-weighted magnetic resonance imaging (MRI) with a novel metabolic imaging modality called hyperpolarized MRI. By measuring the real-time conversion of injected hyperpolarized [1-13C] pyruvate to lactate with hyperpolarized MRI, tumor activity was detected sooner than with conventional MRI during 3 key stages of tumor progression: initial development, regression following radiotherapy treatment, and eventual relapse. These findings were supported by ex vivo metabolomics and histology data and suggest hyperpolarized MRI can provide significant value to the clinic.

Session: HYPERPOLARIZATION, poster number: 247

Methods to Enable Quantitative Preclinical MRI with Hyperpolarized 129Xe 

Peter Niedbalski1; Zackary Cleveland1, 2
1Cincinnati Children's Hospital, Cincinnati, OH; 2University of Cincinnati, Cincinnati, OH

Hyperpolarized (HP) 129Xe MRI has emerged as a sensitive method for probing regional lung function. Herein, we present several methods for improving the efficiency and quantitative accuracy of preclinical HP 129Xe MRI. Using keyhole reconstruction alongside radial imaging enables flip angle mapping with no additional data collection, which can be used to correct images for RF depletion. Furthermore, refocusing gradients (“Flybacks”) can be appended to radial encoding, generating images at multiple effective echo times for mapping T2* with no additional RF pulses. Finally, these advantages of center-out encoding can be combined with efficient spiral trajectories, increasing the speed and reducing gas consumption of scans. We hope that these advancements will help to further the adoption of preclinical HP 129Xe MRI.

Session: HYPERPOLARIZATION, poster number: 248

Hyperpolarized MR and NMR Spectroscopy Reveal Metabolic Biomarkers for Immunotherapy Resistance in Melanoma

Shivanand Pudakalakatti1; Ashvin Jaiswal2; Prasanta Dutta1; Michael Curran2; Pratip Bhattacharya1
1Department of CSI MD Anderson Cancer Center, Houston, TX; 2Department of Immunology MD Anderson Cancer Center, Houston, TX

Cancer immunotherapy has changed the paradigm of cancer treatment. The success rate of immunotherapy treatment is ~40% in melanoma. To increase the success rate there is an urgent need to identify biomarkers and mechanisms of immunotherapy resistance. In this study we have developed melanoma mouse models/cell lines of adoptive immunotherapy resistance and identified molecular mechanisms and biomarkers for immunotherapy resistance employing hyperpolarized MR and NMR spectroscopy. In vitro studies have showed adaptations in metabolic pathways of glycolysis, fatty acid, and purine synthesis in resistant cell lines. In vivo experiments with administered 1-13C hyperpolarized pyruvate revealed higher pyruvate to lactate conversion in immunotherapy resistant mice. Hence, lactate to pyruvate ratio can be a potential in vivo biomarker to identify immunotherapy resistance.

Session: HYPERPOLARIZATION, poster number: 249

Ultra-low Loadings of Platinum on Shaped Cerium Oxide Nanocrystal Supports for Parahydrogen Enhanced NMR

Diana Choi; Bochuan Song; Clifford Russell Bowers; Helena Hagelin-Weaver
University of Florida, Gainesville, FL

Parahydrogen Enhanced NMR (or PHIP) is a hyperpolarization technique used to achieve high-field NMR signal enhancements of up to four orders of magnitude, but only if the hydrogenation occurs in a pairwise fashion, where both protons from the same parahydrogen molecule add to the same substrate molecule. Here, parahydrogen enhanced NMR studies were performed using catalysts with ultra-low loadings of Pt supported on various ceria nanocrystal shapes. The novel catalysts were prepared by a modified Atomic Layer Deposition (ALD) method. Atomically dispersed Pt catalyst, stabilized on the (111) facets of ceria nano-octahedra at a loading of only 8.2ppm, exhibited a remarkable 6% pairwise selectivity for the hydrogenation of propene.

Session: HYPERPOLARIZATION, poster number: 250

Bimetallic Nanoparticles Tailored for Parahydrogen Enhanced NMR by Heterogeneous Catalysis

Tommy Y. Zhao1; Minda Chen2; Yong Du1; Evan W. Zhao1; Raghu Maligal-Ganesh2; Clifford R Bowers1; Wenyu Huang2
1University of Florida, Gainesville, Florida; 2Iowa State University, Ames, IA

Parahydrogen enhanced hyperpolarization by heterogeneous catalysis over supported metal nanoparticles offers facile separation of the solid catalyst, enabling fast, robust and continuous production of contaminant-free hyperpolarized biomolecules. However, signal enhancements achieved by heterogeneous catalysis over monometallic nanoparticle catalysts have been modest due to the fast H ad-atom diffusion and stepwise H ad-atom transfer that randomize the singlet spin order of parahydrogen. This presentation presents tailored design and novel strategies for synthesizing bimetallic catalysts with surface properties that mitigate spin state randomization.  The novel catalytic nanomaterials afford substantially higher signal enhancement factors compared to conventional monometallic nanoparticle catalysts. 23.6% pairwise selectivity is achieved using RhIn3/SBA-15 bimetallic catalyst. Bimetallic catalysts also offer superior stereoselectivity and chemoselectivity in the hydrogenation of alkyne substrates.

Session: HYPERPOLARIZATION, poster number: 251

Insights into the Surface Structure of Nitrogen-functionalized Hydrothermal Carbon Investigated by Specific Cross-Relaxation under DNP

Heeyong Park1, 2; Boran Uluca-Yazgi1; Saskia Heumann2; Robert Schlögl2, 4; Rüdiger-A. Eichel1, 3; Josef Granwehr1, 3; Henrike Heise1, 5; P. Philipp M. Schleker1, 2
1Forschungszentrum Jülich, Jülich, Germany; 2Max Planck Institute for CEC, Mülheim an der Ruhr, Germany; 3RWTH Aachen University, Aachen, Germany; 4Fritz Haber Institute of the Max Planck Society, Berlin, Germany; 5Heinrich Heine Universität Düsseldorf, Düsseldorf, Germany

Dynamic Nuclear Polarization (DNP) under magic-angle spinning (MAS) NMR spectroscopy is a unique analytical method capable of probing surfaces at atomic resolution. Several mechanisms are simultaneously involved when transferring much larger polarization of electron spins to NMR active nuclei during a typical MAS DNP NMR experiment. Recently, specific cross-relaxation enhancement by active motions under DNP (SCREAM-DNP) has been reported as one of these mechanisms. Here, we elucidate how this spontaneous cross-relaxation induced enhancement (CRE) effect under DNP can be utilized to analyze the structural depth-profiling of N-functionalized hydrothermal carbon (N-HTC) particles using the effective reorientation of methyl and amine groups on the surface of N-HTC.

Session: HYPERPOLARIZATION, poster number: 252

Surface Structure Determination of Heterogeneous Catalysts by DNP SENS

Ribal Jabbour1; Pierrick Berruyer2; David Gajan1; Marc Renom-Carrasco3; Cory Widdifield4; Moreno Lelli5; Christophe Copéret6; Lyndon Emsley2; Chloé Thieuleux3; Anne Lesage1
1High-Field NMR Center, Université de Lyon, FRE 203, Villeurbanne, France; 2Institut des Sciences et Ingénierie Chimiques, Lausanne, Switzerland; 3Institut de Chimie de Lyon, LC2P2, UMR 5265, Villeurbanne, France; 4Oakland University, Rochester, MI, 48309-4479, USA; 5Magnetic Resonance Center (CERM), 50019 Sesto Fiorentino (FI), Italy; 6ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland

Dynamic Nuclear Polarization (DNP) has emerged as a powerful technique to amplify the NMR signals of surface species. We have recently demonstrated that the 3D structure of a model organometallic platinum complex anchored on an amorphous silica could be fully determined by DNP Surface enhanced NMR spectroscopy (DNP SENS). Here, we extend this approach and determine the 3D surface structure of an iridium supported catalyst. NMR strategies were developed to measure selectively distance constraints on the Ir complex, in the presence of surface precursor species. The result, in combination with EXAFS, is a well-defined structure determined with a precision of 0.89 Å in which residual organic ligands coordinate the metal center.

Session: HYPERPOLARIZATION, poster number: 253

Simulating CP Mechanics in SIMPSON and Modeling Hyperpolarization in Optically Pumped CdTe

Michael West; Matthew Willmering; Sophia E. Hayes
Washington University, St Louis, MO

Optically Pumped NMR (OPNMR) is a hyperpolarization technique that makes viable the ability to study semiconducting materials, such as CdTe. CdTe is a unique test bed for nuclear spin physics experiments, as NMR-active nuclei within CdTe are relatively isolated from one another.  Even though the system is single-crystal, simulating the cross polarization dynamics of 125Te to 113Cd in SIMPSON is surprisingly complex.  This arises from the fact that there are many possible configurations of NMR-active species in CdTe that all contribute differently to the CP buildup observed in experiment.  Additionally, OPNMR allows for extremely high polarizations which are reflected in experimental spectra.  This phenomenon can be modeled, and the polarization achieved can be measured in a single experiment.

Session: HYPERPOLARIZATION, poster number: 254

99% Parahydrogen Enrichment for the Masses

Yong Du; Maria-Jose Ferrer; Qiuying Li; Clifford Bowers
University of Florida, Gainesville, FL

Parahydrogen (p-H2) mole fraction, χp, is related to polarization levels obtained in p-H2 based hyperpolarization techniques by (1/3)(4χp-1). Commercial high enrichment p-H2 generators are expensive and require 1-2 hours for the cryo-cooler to reach the cryogenic conversion temperature. Here we present an inexpensive and easy-to-operate system for producing high enrichment p-H2 gas. >90% enrichment is observed over a range of pressures and flow rates. Moreover, 99% enrichment is confirmed at 30 K and 65 psi of H2 pressure. The design, construction, and performance data of this low-cost para-enrichment system will be detailed in the poster.

Session: HYPERPOLARIZATION, poster number: 255

Intrinsic Atomic Gradiometer with 0.2 fT/ Hz1/2 Sensitivity and 40 dB Common Mode Noise Rejection.

David W Prescott2; Nezih Dural1; Michael V Romalis1; Karen Sauer2
1Princeton University, Princeton, NJ; 2George Mason University, Fairfax, VA

Atomic magnetometers are used to detect weak magnetic fields for many applications including low-field NMR and explosives detection through NQR.  A gradiometer facilitates operation in an unshielded environment by reducing the common mode noise.   A multi-pass cell with a V-shaped probe beam was constructed to allow for optical subtraction of common mode noise in each voxel in an atomic magnetometer. The optical subtraction is beneficial because it required no post-processing and avoids dynamic range issues. This intrinsic gradiometer was found to have a 0.2 fT/Hz1/2 sensitivity over the full cell dominated by spin-projection noise.  The gradiometer was used to measure a RF gradient signal across the cell and could be adjusted to suppress common mode interference by 40 dB.

Session: HYPERPOLARIZATION, poster number: 256

A Four-Ring Birdcage Head Coil for 1H Imaging and Hyperpolarized 13C Spectroscopy at 3T

Joseph Murphy-Boesch1; Kazutoshi Yamamoto2; Ananda Kumar3; Peter Choyke4; Murali C. Krishna2
1National Institutes of Health, NINDS, Bethesda, MD; 2National Institutes of Health, NCI, Bethesda, MD; 3Lambda-Z Technologies, Baltimore, MD; 4National Institutes of Health, NCI, CCR, Bethesda, MD

Dissolution dynamic nuclear polarization (DNP) techniques have been used to acquire sensitive 13C metabolic images from human tissues in vivo. Using CSI to localize 13C spectra, anerobic metabolism of pyruvate can be monitored to reveal high concentrations of lactate in tumors. Here, a 16-leg four-ring quadrature birdcage is described for 1H imaging and 13C metabolic imaging of the human brain at 3 Tesla.  The 13C sensitivity of the coil was evaluated by imaging hyperpolarized spectra from a nude mouse with a small, human pancreatic tumor MiaPaCa-2 xenograft grown in the flank of its hind leg. Sensitivity was adequate to evaluate the lactate/pyruvate ratio for a tumor voxel < 0.5 ml in volume.

Session: HYPERPOLARIZATION, poster number: 257

Integrated Photonic Band-Gap Resonator Probeheads Provide up to 30-fold Increase of Microwave Powers for DNP at 7T

Alexander A. Nevzorov; Antonin Marek; Sergey Milikisiyants; Alex I. Smirnov
North Carolina State University, Raleigh, NC

Achieving pulse mode of DNP and electron decoupling requires the use of frequency-agile millimeter wave sources while attaining high powers at the sample. As an alternative to the frequency-swept gyrotrons here we have employed solid-state multiplication/amplification chain combined with a high-finesse, high-Q photonic band-gap (PBG) resonator DNP probehead tuned at 200GHz/300 MHz frequencies. The use of high gradients (ca. 10:1) in the dielectric materials for the PBG resonator allowed us to obtain up to 30-fold gain in the effective millimeter wave power at the sample vs. non-resonant configuration. The power enhancement was verified by DNP of natural abundance 13C from microdiamonds embedded in commercial thin (75 μm) lapping films and rationalized by theory and simulations.

Session: HYPERPOLARIZATION, poster number: 258

200 W Ultra-narrow Band Pump Laser Diode System for SEOP

Aleksandr Ryasnyanskiy; V Smirnov; O Mokhun; A. Glebov; L Glebov
OptiGrate Corp, Orlando, FL

We present the first results for 200W narrowband high-power laser diode systems for pumping of Rb atoms. The system not only produces up to 200 W of narrowband light, but also has a unique capability of tuning the emitting wavelength in a range of 300-400 pm. The system is also capable to deliver 894.3 nm for Cs pumping as well as several different wavelengths for hybrid pumping (e.g., 795 and 895 nm) with individual control of each wavelength position. Using VBGs for laser resonator longitudinal mode selection allowed us to narrow the linewidth of individual laser diode bars down to 20 pm.

Session: HYPERPOLARIZATION, poster number: 259

Optically Detected 85Rb / 133Cs Electron Spin Resonance (ODESR) in “Hybrid” Spin-Exchange Optical Pumping Cells with Xenon Density Variance

Justin Porter3; Dustin Basler3; Joseph Plummer1; Graeme Russell2; Bryce Kidd3; Eduard Chekmenev4; Michael J. Barlow2; Boyd M. Goodson3
1University of Cincinnati/ CCHMC, Cincinnati, OH; 2University of Nottingham, Nottingham, United Kingdom; 3Southern Illinois University, Carbondale, IL; 4Wayne State University & Karmanos Cancer Institute, Detroit, MI

We report our continued ODESR studies of “clinical-scale” stopped-flow spin-exchange optical pumping.  Our setup uses a high-power pump laser, 500 cc cell, a waveform generator (WFG) that ramps the magnetic field, a second WFG with output broadcast through an RF coil, a probe laser, and a photodiode connected to an RF lockin amplifier that records ODESR signals. “Pump”/”probe” lasers at D1 wavelengths for both Cs / Rb allow 4 different configurations when studying “hybrid” Cs/Rb cells. 85Rb and 133Cs ODESR spectra can be recorded as functions cell temperature, [Xe], laser power, and pump light polarization—allowing extrapolation of the alkali metal polarization under conditions where the ESR lines are otherwise too broadened (e.g. high Xe density and resonant laser flux).


Session: HYPERPOLARIZATION, poster number: 260

Catalyst Selection in a Para-Hydrogen Generator

Julian Sacharnoski; Daniel Metzger; Matthew Gilpin; Nicholas Whiting
Rowan University, Glassboro, NJ

We present our initial efforts in creating a low-cost liquid nitrogen cooled parahydrogen (pH2) generator and report a comprehensive study of different catalysts for converting normal hydrogen gas into pH2 under a given set of experimental conditions. The pH2 generator consists of a 3 m (1/4” OD) copper tube filled with 25 mL of each catalyst, with an H2 flow rate of 60 mL/min at 50 psi. Results indicate that metal oxide powders (e.g., Fe2O3) provide highly efficient conversion to pH2, while other metal powders (e.g., Mn) and pourous media (e.g., carbon powder) provide neglibible conversion to pH2 under the listed conditions. We also evaluate the catalysts for surface area and magnetic susceptibility to determine favorable catalyst properties.

Session: HYPERPOLARIZATION, poster number: 261

Making Unshielded RF Magnetometers Insensitive to Environmental Perturbations

Robert J. Cooper; Daniel A. Rodriguez Castillo; David W Prescott; Karen L. Sauer
George Mason University, Fairfax, VA

Atomic magnetometers are well suited for the detection of low-field NMR signals as they are easily tunable, don’t capacitively couple to the surroundings, and are more sensitive than coil detectors in the AM band. A two-pass potassium 7.5-cm3 vapor cell in a crossed pump-probe configuration is shown to have a sensitivity ~3 fT/Hz1/2.  A small magnetic field tunes the magnetometers and signals are detected through ESR.  Perturbation along the applied field results in a frequency shift and degradation of performance. The direction of a reoccurring perturbation, such as from an elevator, is determined by tracking the FID frequency shifts while the applied field direction is varied.  The magnetometer is then rotated so that it is insensitive to the perturbing fields.

Session: HYPERPOLARIZATION, poster number: 262

High contrast dual-mode optical and hyperpolarized 13C magnetic resonance imaging in diamond particles

Xudong Lv1; Jeffrey Walton2; Emanuel Druga1; Alessandra Aguilar1; Lan Wu1; Olga Shenderova3; Daniel Vigneron4; Carlos Carlos5; Jeffrey Reimer1; Alexander Pines1; Ashok Ajoy1
1UC Berkeley, Berkeley, CA; 2UC Davis, Davis, CA; 3Admas Nanotechnologies, Inc, Raleigh, NC; 4UCSF, San Francisco, CA; 5CUNY-City College of New York, New York, NY

In this work, we integrate optical and MR imaging in diamond particles endowed with a high density of quantum defects, NV centers. Under optical excitation, NV centers fluoresce brightly in the visible, as well as electron spin polarize, allowing the hyperpolarization of lattice 13C nuclei to make the particle MRI over three-orders of magnitude brighter than conventionally possible. Leveraging the ability of optical and MR imaging to simultaneously probe Fourier-reciprocal domains (real and k-space), we elucidate the ability to employ hybrid sub-sampling in both conjugate spaces to accelerate image acquisition, while reducing the net optical power, by two orders of magnitude. This work portends new avenues for quantum-enhanced dual-mode imaging platforms and opens possibilities for new therapeutic avenues including in low-field MRI-guided endoscopy.

Session: HYPERPOLARIZATION, poster number: 263

NMR of 131Xe Spin Exchange Optical Pumping in Aluminosilicate (GE180) Cells: Targets for Neutron Optics Searches for Time-Reversal Invariance Violation

Dustin J. Basler1; Kierstyn Albin1; Liana Bales1; Abdulbasit Tobi Gafar1; Hao Lu2; Michael Snow3; Earl Babcock3; Eduard Chekmenev4; Michael J. Barlow5; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2Indiana University, Bloomington, IN; 3Jülich Centre for Neutron Science, Jülich , Germany; 4Wayne State University & Karmonos Cancer Institute, Detroit, MI; 5University of Nottingham, Nottingham, United Kingdom

The discovery of new sources of time-reversal invariance violation (TRIV) may be the best places to look for new physical interactions that may help explain certain observations of the universe.  In support of the efforts of the NOPTREX collaboration, we are working to develop hyperpolarized 131Xe in aluminosilicate (GE180) cells as targets for neutron optics searches for TRIV.  SEOP is performed with a 180 W spectrally narrowed laser and monitored via transmission near-IR spectroscopy and in situ low-field NMR, calibrated with thermally polarized water signals—allowing PXe values to be estimated.  Current efforts concern more precise calculation of PXe values and optimizing PXe as a function of cell temperature and laser offset, prior to performing initial neutron beam experiments.

Session: HYPERPOLARIZATION, poster number: 264

Indirect Cross-Effect with Chirped MW Irradiation

Daphna Shimon; Ilia Kaminker
Tel Aviv University, Tel Aviv, Israel

Several years ago, the Vega group suggested that the indirect cross-effect (iCE) is the dominant dynamic nuclear polarization (DNP) mechanism under static (non-MAS) conditions. In a recent publication, the Han group suggested that main source of improved DNP enhancement under broadband microwave irradiation, either in the form of frequency modulation or coherent chirp pulses, is due to the modification of the electron-polarization-profile improving the iCE-DNP performance.

We introduce an improved iCE model that combines electron-electron spectral diffusion with broadband microwave irradiation. This model can successfully simulate experimental electron polarization profiles under broadband microwave irradiation (i.e. electron-electron double resonance spectra) and experimentally observed effects in the DNP experiments under varying experimental conditions.

Session: HYPERPOLARIZATION, poster number: 265

Advances in High-Density Batch-Mode 129Xe Hyperpolarization Using Spin-Exchange Optical Pumping

Jonathan Birchall1; Peter Nikolaou2; Robert Irwin3; Aaron Coffey4; Ekaterina Pokochueva5, 6; Bryce Kidd7; Megan Murphy7; Michael Molway7; Liana Bales7; Kaili Ranta7; Michael Barlow3; Kirill Kovtunov5, 6; Igor Koptyug5, 6; Boyd Goodson7; Eduard Chekmenev1, 8
1Wayne State University, Detroit, MI; 2XeUS Technologies LTD, Nicosia, Cyprus; 3University of Nottingham, Nottingham, United Kingdom; 4Vanderbilt University, Nashville, TN; 5Novosibirsk State University, Novosibirsk, Russia; 6International Tomography Center SB RAS, Novosibirsk, Russia; 7Southern Illinois University, Carbondale, IL; 8Russian Academy of Sciences, Moscow, Russia

Hyperpolarization of 129Xe using batch-mode Spin-Exchange Optical Pumping (SEOP) is demonstrated at high Xe-densities and partial pressures (up to 1330 Torr Xe partial pressure), and on rapid polarization build-up timescales. 4He-rich gas mixtures are employed, generating record-high levels of 129Xe polarization (85.1 ± 2.7% at 1000 Torr Xe partial pressure, 73.9 ± 1.9% at 1330 Torr Xe partial pressure), elevated build-up rates and improved SEOP cell thermal stability. Additionally, a novel aluminum heating jacket design is utilized to perform rapid temperature cycling of SEOP cells in 4 minutes: six-fold faster than previous-generation hyperpolarizers. The feasibility of ultra-fast SEOP at build-up rates exceeding 0.2 min-1 is also demonstrated, assisting in increased production rates for clinical-scale 129Xe contrast agent production.

Session: HYPERPOLARIZATION, poster number: 266

Harnessing optical 13C hyperpolarization in diamond for dual-mode imaging and quantum sensing

Ashok Ajoy1; Emanuel Druga1; Pasha Reshetikhin1; Xudong Lv1; Priyanka Raghavan1; Valentin Krespach1; Dieter Suter2; Olga Shenderova3; Carlos Meriles4; Jeffrey Reimer1; Alexander Pines1
1UC Berkeley, Berkeley, CA; 2TU Dortmund, Dortmund, Germany; 3Adamas Nanotechnologies, Raleigh, NC; 4CCNY, NY, NY

We highlight new advances in the generation of optical 13C hyperpolarization in diamond employing optically polarizable Nitrogen Vanacy centers. We demonstrate new materials processing techniques involving rapid annealing at ultra-high temperatures that suppress paramagnetic triplet centers and boost hyperpolarization levels by an order of magnitude. We harness the obtained 13C hyperpolarization for new applications in imaging, quantum sensing, and magnetometry, leveraging the co-location of fluorescent NV electrons and 13C nuclear spins in the same platform.