Journal of Magnetic Resonance Open最新文献

{"title":"Electron spin polarization in the triplet state of methoxy-substituted phosphorus(V) tetraphenyl porphyrins","authors":"D. Panariti ,&nbsp;B.J. Bayard ,&nbsp;A. Barbon ,&nbsp;Y.E. Kandrashkin ,&nbsp;P.K. Poddutoori ,&nbsp;A. van der Est ,&nbsp;M. Di Valentin","doi":"10.1016/j.jmro.2024.100169","DOIUrl":"10.1016/j.jmro.2024.100169","url":null,"abstract":"<div><div>Photoexcited triplet states of porphyrins are of great relevance in various applications due to their high yield, long lifetime, and strong electron spin polarization. This study delves into properties and spin dynamics of the triplet state of a series of hypervalent phosphorus(V) porphyrins. Transient Electron Paramagnetic Resonance (TrEPR) measurements, supported by quantum chemical calculations as well as by optical absorption/luminescence experiments, reveal that, unlike singlet states, the lowest triplet state does not exhibit charge-transfer (CT) character upon photoexcitation. However, the presence of excited CT singlet states alters the intersystem crossing in phosphorus(V) porphyrins, leading to a sign change in the initial multiplet polarization of the photoexcited triplet state. TrEPR results further demonstrate that significant net polarization develops in the triplet states of the phosphorus(V) porphyrins due to the dynamic Jahn-Teller effect. Yet, this effect remains largely unaffected by differences in their molecular structures.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100169"},"PeriodicalIF":2.624,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural abundance 195Pt-13C correlation NMR spectroscopy on surfaces enabled by fast MAS dynamic nuclear polarization","authors":"Zhuoran Wang ,&nbsp;Thomas C. Robinson ,&nbsp;Domenico Gioffrè ,&nbsp;Rochlitz Lukas ,&nbsp;David Gajan ,&nbsp;Aaron J. Rossini ,&nbsp;Christophe Copéret ,&nbsp;Anne Lesage","doi":"10.1016/j.jmro.2024.100167","DOIUrl":"10.1016/j.jmro.2024.100167","url":null,"abstract":"<div><div>Surface organometallic chemistry has developed as an effective strategy for the rational design and synthesis of well-defined, single-site Pt-based heterogeneous catalysts. Given its high sensitivity to changes in electronic structure, ¹⁹⁵Pt solid-state NMR spectroscopy offers a unique approach to investigate the chemical structure and local environment of Pt surface sites, providing invaluable insights for establishing structure-activity relationships. However, this approach is typically hindered by severe sensitivity issues, due to the low loading of Pt sites and the often-encountered large ¹⁹⁵Pt chemical shift anisotropies. To overcome this limitation, ¹⁹⁵Pt NMR signature of surface metal centers can be indirectly detected through protons. Indirect detection on ¹³C spins, has also been demonstrated to be feasible by combining isotopic labeling with dynamic nuclear polarization (DNP). Here, we extend this methodology to a supported Pt complex at natural abundance. The material was prepared by grafting <strong>(COD)PtMeOSi(O<em>t</em>Bu)₃</strong> (COD = 1,5-cyclooctadiene, Me = methyl and <em>t</em>Bu = <em>tert</em>‑butyl) onto partially dehydroxylated silica. DNP enhanced two-dimensional through-bond ¹³C{¹⁹⁵Pt} heteronuclear correlation experiments were successfully implemented at fast magic angle spinning. They enabled the detection of the 0.37 % NMR-responsive surface species, thereby showcasing the remarkable sensitivity of this approach and its broad applicability. Key bonding information was obtained by measuring the correlated ¹³C and ¹⁹⁵Pt isotopic chemical shifts as well as ¹<em>J</em>(¹³C-¹⁹⁵Pt) coupling constants, confirming directly the coordination structure of the surface Pt sites.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100167"},"PeriodicalIF":2.624,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear hyperpolarization in electron-transfer proteins: Revealing unexpected light-induced 15N signals with field-cycling magic-angle spinning NMR","authors":"Patrick Kurle-Tucholski ,&nbsp;Luca Gerhards ,&nbsp;Yonghong Ding ,&nbsp;Yunmi Kim ,&nbsp;Irina S. Anisimova ,&nbsp;A. Alia ,&nbsp;Ilia A. Solov'yov ,&nbsp;Jörg Matysik","doi":"10.1016/j.jmro.2024.100168","DOIUrl":"10.1016/j.jmro.2024.100168","url":null,"abstract":"<div><div>The solid-state photo-CIDNP (photo-chemically induced dynamic nuclear polarization) effect allows for nuclear hyperpolarization, i.e., non-Boltzmann nuclear spin population. The effect relies on the light-induced formation of a spin-correlated radical pair (SCRP) and has been observed in various photosynthetic reaction center (RC) proteins and flavin-containing light, oxygen, voltage (LOV) proteins. Both systems exhibit strongly enhanced NMR signals originating from the electron transfer partners. Here, we present experimental data on the magnetic field dependence of the ¹⁵N solid-state photo-CIDNP effect in both phototropin LOV1 C57S from <em>Chlamydomonas reinhardtii</em> and the bacterial photosynthetic RC from <em>Rhodobacter sphaeroides.</em> Using a pneumatic field-cycling system, samples containing a frozen solution of the proteins are explored between 0.25 T and 9.4 T. Both systems yield hyperpolarized ¹⁵N NMR signals across the entire magnetic field range originating from the electron transfer moieties. Also, in both systems, hyperpolarized signals from unexpected positions are detected between 1.0 T and 2.0 T: position N-1 of the flavin in the LOV1 protein and the τ-N of the axial magnesium-coordinating histidine of the donor. A first attempt to explain the occurrence of these unexpected signals based on quantum chemical calculations is presented.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100168"},"PeriodicalIF":2.624,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement and modeling of xenon gas transfer in the human brain with 1H and hyperpolarized 129Xe MRI","authors":"Graham Norquay ,&nbsp;Madhwesha R Rao ,&nbsp;Jim M Wild","doi":"10.1016/j.jmro.2024.100166","DOIUrl":"10.1016/j.jmro.2024.100166","url":null,"abstract":"<div><h3>Background</h3><div>The feasibility of imaging hyperpolarized ¹²⁹Xe dissolved in brain tissue following inhalation of xenon gas in the lungs has recently been demonstrated in humans. The image contrast in ¹²⁹Xe brain MRI represents a combination of factors, including regional perfusion, polarization decay and gas transfer rate across the blood-brain barrier.</div></div><div><h3>Purpose</h3><div>To investigate the repeatability of hyperpolarized ¹²⁹Xe brain MRI in healthy normal individuals and to identify the dominant mechanisms of image contrast by assessing voxel-wise correlation between HP ¹²⁹Xe brain MRI and models of ¹²⁹Xe brain uptake derived from ¹H arterial spin labeling (ASL) perfusion mapping.</div></div><div><h3>Materials and Methods</h3><div>To assess repeatability, 3 sets of hyperpolarized ¹²⁹Xe brain images were acquired from 5 healthy volunteers. Quantitative maps of the human brain, including cerebral blood flow, volume and predicted xenon uptake, were derived from ¹H arterial spin labeling and <em>T</em>₂-weighted MRI. These maps were then spatially cross-correlated with hyperpolarized ¹²⁹Xe brain MRI.</div></div><div><h3>Results</h3><div>Signal to noise ratios of 8.7–17.7 were observed across volunteers for a voxel size of 8 × 8 × 50 mm³ with intra-subject repeatability of between 6 and 29 %. Hyperpolarized ¹²⁹Xe brain images showed voxel-wise correlations with cerebral blood flow (<em>R</em> = 0.32 to 0.62), volume (<em>R</em> = 0.33 to 0.63) and predicted xenon uptake (<em>R</em> = 0.34 to 0.63), but did not correlate with arterial transit time (<em>R</em> = 0.05 to 0.26).</div></div><div><h3>Conclusion</h3><div>Voxel-wise cross correlation between ¹²⁹Xe and ¹H ASL suggests that the regional quantity of dissolved xenon delivered by cerebral blood flow is the dominant mechanism of image contrast in HP ¹²⁹Xe brain MRI, assuming normal blood-brain barrier function. Combining ¹H and ¹²⁹Xe brain MRI provides new opportunities to quantitatively investigate brain pathophysiology and function.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100166"},"PeriodicalIF":2.624,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"13C-Formate as an indirect low-temperature 1H lineshape polarimeter","authors":"Stuart J. Elliott ,&nbsp;Quentin Stern,&nbsp;Sami Jannin","doi":"10.1016/j.jmro.2024.100162","DOIUrl":"10.1016/j.jmro.2024.100162","url":null,"abstract":"<div><div>¹H polarization quantification is important for dissolution-dynamic nuclear polarization (<em>d</em>DNP) but can be cumbersome due to the requirement of acquiring thermal equilibrium signals and measurements that are complicated by large background signals. ¹H nuclear magnetic resonance (NMR) spectra can also be deleteriously influenced by line distortions linked with radiation damping from ¹H DNP and cannot be used for accurate calculation of ¹H polarization. Determining ¹H polarization via immediate ¹³C lineshape analysis of a simple molecule removes such complications. We present ¹³C-sodium formate as a straightforward system for indirect ¹H polarimetry. The ¹³C NMR spectra acquired under <em>d</em>DNP conditions have distinct features that are readily reproduced with ¹³C lineshape simulations. ¹H polarizations built-up during ¹H DNP were indirectly inferred by fitting simulations to ¹³C lineshapes. We provide the <em>MATLAB</em> scripts used for ¹³C lineshape analysis in order that the method can be readily implemented in other laboratories.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100162"},"PeriodicalIF":2.624,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of biomolecular dynamics by sensitivity-enhanced 1H–2H CPMAS NMR using matrix-free dynamic nuclear polarization","authors":"Thomas Biedenbänder ,&nbsp;Aryana Rodgers ,&nbsp;Mirjam Schröder ,&nbsp;Liliya Vugmeyster ,&nbsp;Björn Corzilius","doi":"10.1016/j.jmro.2024.100161","DOIUrl":"10.1016/j.jmro.2024.100161","url":null,"abstract":"<div><div>Molecular dynamics of functional groups contain valuable information about structural properties and functional activities in biomolecules. NMR spectroscopy is a sensitive tool for the investigation of molecular dynamics over a wide range of timescales and thus may deepen the understanding of the biomolecules of interest. Here, we present an approach to use DNP-enhanced ²H NMR to study dynamics of selectively deuterated methyl groups in insoluble proteins such as amyloid beta (Aβ) fibrils. We adopted and optimized the matrix-free DNP approach by varying the amount of added polarizing agent as well as the rehydration level of model proteins. We show that the DNP enhancement obtained in ¹H–²H cross-polarization (CP) MAS spectra may increase the sensitivity for selectively deuterated Aβ fibril samples by more than one order of magnitude, accelerating the collection of spin-lattice relaxation data in the DNP-accessible temperature range between 100 and 150 K by up to 400-fold. However, below the coalescence temperature, which describes the transition from the fast to the slow exchange regime, the experimentally obtained relaxation time constants suffer from a paramagnetic relaxation enhancement effect due to the presence of the polarizing agent. This seems to be a general effect for biomolecules as it is also confirmed for two other protein model systems. Our demonstration opens the possibility to extend the scope of ²H NMR for dynamics measurements to effective concentrations and/or temperatures below what is currently accessible; however, the observed interplay between paramagnetic relaxation and molecular dynamics also emphasizes the necessity for a better understanding of relaxation effects in DNP-enhanced NMR.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100161"},"PeriodicalIF":2.624,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DNP enhanced solid-state NMR – A powerful tool to address the surface functionalization of cellulose/paper derived materials","authors":"Mark V. Höfler ,&nbsp;Jonas Lins ,&nbsp;David Seelinger ,&nbsp;Lukas Pachernegg ,&nbsp;Timmy Schäfer ,&nbsp;Stefan Spirk ,&nbsp;Markus Biesalski ,&nbsp;Torsten Gutmann","doi":"10.1016/j.jmro.2024.100163","DOIUrl":"10.1016/j.jmro.2024.100163","url":null,"abstract":"<div><div>This concept summarizes recent advances in development and application of DNP enhanced multinuclear solid-state NMR to study the molecular structure and surface functionalization of cellulose and paper-based materials. Moreover, a novel application is presented where DNP enhanced ¹³C and ¹⁵N solid-state NMR is used to identify structure moieties formed by cross-linking of hydroxypropyl cellulose. Given these two aspects of this concept-type of article, we thus combine both, a review on recent findings already published and unpublished recent data that complement the existing knowledge in the field of characterization of functional lignocellulosic materials by DNP enhanced solid-state NMR.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100163"},"PeriodicalIF":2.624,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual hyperpolarized [1-13C]pyruvate and [13C]urea magnetic resonance imaging of prostate cancer","authors":"Ivan de Kouchkovsky ,&nbsp;Hao Nguyen ,&nbsp;Hsin-Yu Chen ,&nbsp;Xiaoxi Liu ,&nbsp;Hecong Qin ,&nbsp;Bradley A. Stohr ,&nbsp;Romelyn Delos Santos ,&nbsp;Michael A. Ohliger ,&nbsp;Zhen Jane Wang ,&nbsp;Robert A. Bok ,&nbsp;Jeremy W. Gordon ,&nbsp;Peder E.Z. Larson ,&nbsp;Mary Frost ,&nbsp;Kimberly Okamoto ,&nbsp;Daniel Gebrezgiabhier ,&nbsp;Matthew Cooperberg ,&nbsp;Daniel B. Vigneron ,&nbsp;John Kurhanewicz ,&nbsp;Rahul Aggarwal","doi":"10.1016/j.jmro.2024.100165","DOIUrl":"10.1016/j.jmro.2024.100165","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Background&lt;/h3&gt;&lt;p&gt;Although multiparametric (mp) &lt;sup&gt;1&lt;/sup&gt;H magnetic resonance imaging (MRI) is increasingly used to detect and localize prostate cancer (PC), its correlation with tumor grade is limited. Hyperpolarized (HP) carbon-13 (&lt;sup&gt;13&lt;/sup&gt;C) MR is an emerging imaging technique, which can be used to interrogate key biologic processes through in vivo detection of various HP probes. A distinct attribute of HP &lt;sup&gt;13&lt;/sup&gt;C MRI is the ability to detect multiple HP probes within a single acquisition. Here we report on the first simultaneous dual HP [1-&lt;sup&gt;13&lt;/sup&gt;C]pyruvate and [&lt;sup&gt;13&lt;/sup&gt;C]urea MRI with correlations to histopathologic findings in a patient with localized PC scheduled for radical prostatectomy.&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Material and methods&lt;/h3&gt;&lt;p&gt;Paired HP &lt;sup&gt;13&lt;/sup&gt;C and standard mp &lt;sup&gt;1&lt;/sup&gt;H MRI were performed in a patient with biopsy-proven Gleason score 4 + 3 = 7 adenocarcinoma of the prostate scheduled for radical prostatectomy through a first-in-human pilot study of dual-agent HP MRI (NCT02526368). HP &lt;sup&gt;13&lt;/sup&gt;C MRI was performed using a clinical 3T scanner with &lt;sup&gt;13&lt;/sup&gt;C transmit-and-receive capabilities. Dynamic series of HP &lt;sup&gt;13&lt;/sup&gt;C pyruvate, lactate and urea imaging were acquired following intravenous (IV) injection of co-hyperpolarized [&lt;sup&gt;13&lt;/sup&gt;C]urea (25 mM) and [1–&lt;sup&gt;13&lt;/sup&gt;C]pyruvate (125 mM). The [1-&lt;sup&gt;13&lt;/sup&gt;C]pyruvate-to-[1-&lt;sup&gt;13&lt;/sup&gt;C]lactate conversion rate (k&lt;sub&gt;PL&lt;/sub&gt;) was calculated using an inputless two-site exchange model; AUC&lt;sub&gt;urea&lt;/sub&gt; was the [&lt;sup&gt;13&lt;/sup&gt;C]urea signal summed over time. Following radical prostatectomy, whole-mount prostate histopathological slides were prepared and reviewed by an experienced genitourinary pathologist.&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results&lt;/h3&gt;&lt;p&gt;Following informed consent, the patient underwent paired mp &lt;sup&gt;1&lt;/sup&gt;H MRI and dual-agent HP MRI. mp &lt;sup&gt;1&lt;/sup&gt;H MRI revealed a 1.2 cm lesion in the left apical posterior zone. Dual-agent HP MRI identified a focus of increased [1-&lt;sup&gt;13&lt;/sup&gt;C]pyruvate-to-[1-&lt;sup&gt;13&lt;/sup&gt;C]lactate conversion rate (k&lt;sub&gt;PL&lt;/sub&gt;) extending from the left apical posterior peripheral zone to the right gland. A corresponding area of abnormal tissue perfusion (AUC&lt;sub&gt;urea&lt;/sub&gt;) was seen in the left gland. Metabolism-perfusion mismatch (with several foci of increased &lt;em&gt;k&lt;sub&gt;PL&lt;/sub&gt;&lt;/em&gt;/AUC&lt;sub&gt;urea&lt;/sub&gt;) was observed throughout the tumor. Tumor extension to the right midgland was confirmed at the time of radical prostatectomy and staining for lactate dehydrogenase-A was increased throughout the tumor relative to surrounding benign prostatic tissue.&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Conclusion&lt;/h3&gt;&lt;p&gt;This first-in-human radiopathologic study demonstrates the feasibility of dual-agent HP MRI in PC patients. Simultaneous assessment of tumor metabolism and perfusion was able to detect occult disease as well as to show a significant mismatch between intra-tumoral metabolism and tissue perfusion in high-grade PC. ","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100165"},"PeriodicalIF":2.624,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666441024000207/pdfft?md5=7b66657cb74e70c1242c4491d6fa3a40&pid=1-s2.0-S2666441024000207-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discontinuous hyperpolarization schemes in liquid-state overhauser dynamic nuclear polarization experiments","authors":"Alex van der Ham","doi":"10.1016/j.jmro.2024.100160","DOIUrl":"10.1016/j.jmro.2024.100160","url":null,"abstract":"<div><p>Liquid-state Overhauser Dynamic Nuclear Polarization (ODNP) is an emerging technique, aimed at shortening NMR experiment times. It achieves this by increasing the otherwise poor nuclear polarization at room temperature, by polarization transfer from excited electron spins. The present work explores two ideas, aimed at achieving the optimal signal-to-noise per time unit for a given system, and quantitation of spectra showing a large disparity in ODNP enhancements at high magnetic fields (≥ 9.4 T). Both of these ideas are predicated on, perhaps counterintuitively, not allowing full dynamic nuclear polarization to build up, either by rapid rf pulsing, or gating of the microwave irradiation.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100160"},"PeriodicalIF":2.624,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666441024000153/pdfft?md5=1b851004339d56ccb0489d8db665fe26&pid=1-s2.0-S2666441024000153-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Creating high, portable proton polarization with photo-excited triplet DNP","authors":"P. Hautle,&nbsp;W.Th. Wenckebach","doi":"10.1016/j.jmro.2024.100159","DOIUrl":"10.1016/j.jmro.2024.100159","url":null,"abstract":"<div><p>Dynamic nuclear polarization (DNP) is a powerful tool to polarize nuclear spins and enhance the intensity of their magnetic resonance signal. For DNP a sample is doped with an agent providing unpaired electron spins. Then the sample is cooled in a strong magnetic field to polarize these electron spins and a microwave field is applied to transfer this polarization to the nuclear spins. While DNP is very efficient, it has two inherent issues: the electron spins needed to polarize the nuclear spins are also the main source of polarization decay. Furthermore, polarizing the electron spins requires strong magnets and powerful cryogenics, that may obstruct further use of the polarized nuclear spins.</p><p>These issues can be addressed by using the electron spin of photo-excited triplet states for DNP. After DNP the light creating the electron spins can be shut off, thus eliminating the main source of decay of the nuclear polarization. Moreover, for some well-chosen molecules the photo-excitation process creates the triplet state in a highly polarized state, so magnets and cryogenics can be significantly simplified.</p><p>The present article presents the state of the art of producing a high proton polarization – up to 0.80 – with a long lifetime – typically 50 h at liquid nitrogen temperature and in a field of 0.75 T – using the photo-excited triplet state of pentacene in a naphthalene host. It describes sample preparation, experimental equipment and procedures required to obtain this result, as well the theoretical background required to maximize the polarization transfer from the triplet spins to the proton spins and to optimize the photo-excitation process. It finishes with methods for long-distance transport and final application of polarized samples.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"20 ","pages":"Article 100159"},"PeriodicalIF":2.624,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666441024000141/pdfft?md5=002d182c52f0ebba51698515177991e9&pid=1-s2.0-S2666441024000141-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}