共查询到20条相似文献,搜索用时 46 毫秒
1.
Dr. Nikita V. Chukanov Prof. Roman V. Shchepin Dr. Sameer M. Joshi Mohammad S. H. Kabir Dr. Oleg G. Salnikov Alexandra Svyatova Prof. Igor V. Koptyug Prof. Juri G. Gelovani Prof. Eduard Y. Chekmenev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9727-9736
NMR hyperpolarization techniques enhance nuclear spin polarization by several orders of magnitude resulting in corresponding sensitivity gains. This enormous sensitivity gain enables new applications ranging from studies of small molecules by using high-resolution NMR spectroscopy to real-time metabolic imaging in vivo. Several hyperpolarization techniques exist for hyperpolarization of a large repertoire of nuclear spins, although the 13C and 15N sites of biocompatible agents are the key targets due to their widespread use in biochemical pathways. Moreover, their long T1 allows hyperpolarized states to be retained for up to tens of minutes. Signal amplification by reversible exchange (SABRE) is a low-cost and ultrafast hyperpolarization technique that has been shown to be versatile for the hyperpolarization of 15N nuclei. Although large sensitivity gains are enabled by hyperpolarization, 15N natural abundance is only ∼0.4 %, so isotopic labeling of the molecules to be hyperpolarized is required in order to take full advantage of the hyperpolarized state. Herein, we describe selected advances in the preparation of 15N-labeled compounds with the primary emphasis on using these compounds for SABRE polarization in microtesla magnetic fields through spontaneous polarization transfer from parahydrogen. Also, these principles can certainly be applied for hyperpolarization of these emerging contrast agents using dynamic nuclear polarization and other techniques. 相似文献
2.
Alexandra Svyatova Dr. Ivan V. Skovpin Dr. Nikita V. Chukanov Dr. Kirill V. Kovtunov Prof. Eduard Y. Chekmenev Dr. Andrey N. Pravdivtsev Prof. Jan-Bernd Hövener Prof. Igor V. Koptyug 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8465-8470
Magnetic Resonance Imaging (MRI) is a powerful non-invasive diagnostic method extensively used in biomedical studies. A significant limitation of MRI is its relatively low signal-to-noise ratio, which can be increased by hyperpolarizing nuclear spins. One promising method is Signal Amplification By Reversible Exchange (SABRE), which employs parahydrogen as a source of hyperpolarization. Recent studies demonstrated the feasibility to improve MRI sensitivity with this hyperpolarization technique. Hyperpolarized 15N nuclei in biomolecules can potentially retain their spin alignment for tens of minutes, providing an extended time window for the utilization of the hyperpolarized compounds. In this work, we demonstrate for the first time that radio-frequency-based SABRE hyperpolarization techniques can be used to obtain 15N MRI of biomolecule 1-15N-nicotinamide. Two image acquisition strategies were utilized and compared: Single Point Imaging (SPI) and Fast Low Angle SHot (FLASH). These methods demonstrated opportunities of high-field SABRE for biomedical applications. 相似文献
3.
Prof. Dr. Roman V. Shchepin Dr. Jonathan R. Birchall Dr. Nikita V. Chukanov Dr. Kirill V. Kovtunov Prof. Dr. Igor V. Koptyug Prof. Dr. Thomas Theis Prof. Dr. Warren S. Warren Prof. Dr. Juri G. Gelovani Prof. Dr. Boyd M. Goodson Prof. Dr. Sepideh Shokouhi Prof. Dr. Matthew S. Rosen Prof. Dr. Yi-Fen Yen Prof. Dr. Wellington Pham Prof. Dr. Eduard Y. Chekmenev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8829-8836
The NMR hyperpolarization of uniformly 15N-labeled [15N3]metronidazole is demonstrated by using SABRE-SHEATH. In this antibiotic, the 15NO2 group is hyperpolarized through spin relays created by 15N spins in [15N3]metronidazole, and the polarization is transferred from parahydrogen-derived hydrides over six chemical bonds. In less than a minute of parahydrogen bubbling at approximately 0.4 μT, a high level of nuclear spin polarization (P15N) of around 16 % is achieved on all three 15N sites. This product of 15N polarization and concentration of 15N spins is around six-fold better than any previous value determined for 15N SABRE-derived hyperpolarization. At 1.4 T, the hyperpolarized state persists for tens of minutes (relaxation time, T1≈10 min). A novel synthesis of uniformly 15N-enriched metronidazole is reported with a yield of 15 %. This approach can potentially be used for synthesis of a wide variety of in vivo metabolic probes with potential uses ranging from hypoxia sensing to theranostic imaging. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(40):12280-12284
Diazirines are an attractive class of potential molecular tags for magnetic resonance imaging owing to their biocompatibility and ease of incorporation into a large variety of molecules. As recently reported, 15N2‐diazirine can be hyperpolarized by the SABRE‐SHEATH method, sustaining both singlet and magnetization states, thus offering a path to long‐lived polarization storage. Herein, we show the generality of this approach by illustrating that the diazirine tag alone is sufficient for achieving excellent signal enhancements with long‐lasting polarization. Our investigations reveal the critical role of Lewis basic additives, including water, on achieving SABRE‐promoted hyperpolarization. The application of this strategy to a 15N2‐diazirine‐containing choline derivative demonstrates the potential of 15N2‐diazirines as molecular imaging tags for biomedical applications. 相似文献
5.
Computational (DFT) and Experimental (EXAFS) Study of the Interaction of [Ir(IMes)(H)2(L)3] with Substrates and Co‐substrates Relevant for SABRE in Dilute Systems
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Bram J. A. van Weerdenburg Anthonius H. J. Engwerda Nan Eshuis Dr. Alessandro Longo Dr. Dipanjan Banerjee Dr. Marco Tessari Dr. Célia Fonseca Guerra Prof. Dr. Floris P. J. T. Rutjes Prof. Dr. F. Matthias Bickelhaupt Dr. Martin C. Feiters 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10482-10489
Signal amplification by reversible exchange (SABRE) is an emerging hyperpolarization method in NMR spectroscopy, in which hyperpolarization is transferred through the scalar coupling network of para‐hydrogen derived hydrides in a metal complex to a reversibly bound substrate. Substrates can even be hyperpolarized at concentrations below that of the metal complex by addition of a suitable co‐substrate. Here we investigate the catalytic system used for trace detection in NMR spectroscopy with [Ir(IMes)(H)2(L)3]+ (IMes=1,3‐dimesitylimidazol‐2‐ylidene) as catalyst, pyridine as a substrate and 1‐methyl‐1,2,3‐triazole as co‐substrate in great detail. With density functional theory (DFT), validated by extended X‐ray absorption fine structure (EXAFS) experiments, we provide explanations for the relative abundance of the observed metal complexes, as well as their contribution to SABRE. We have established that the interaction between iridium and ligands cis to IMes is weaker than that with the trans ligand, and that in mixed complexes with pyridine and triazole, the latter preferentially takes up the trans position. 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10569-10573
The hyperpolarization of heteronuclei via signal amplification by reversible exchange (SABRE) was investigated under conditions of heterogeneous catalysis and microtesla magnetic fields. Immobilization of [IrCl(COD)(IMes)], [IMes=1,3‐bis(2,4,6‐trimethylphenyl), imidazole‐2‐ylidene; COD=cyclooctadiene] catalyst onto silica particles modified with amine linkers engenders an effective heterogeneous SABRE (HET‐SABRE) catalyst that was used to demonstrate a circa 100‐fold enhancement of 15N NMR signals in 15N‐pyridine at 9.4 T following parahydrogen bubbling within a magnetic shield. No 15N NMR enhancement was observed from the supernatant liquid following catalyst separation, which along with XPS characterization supports the fact that the effects result from SABRE under heterogeneous catalytic conditions. The technique can be developed further for producing catalyst‐free agents via SABRE with hyperpolarized heteronuclear spins, and thus is promising for biomedical NMR and MRI applications. 相似文献
7.
Max E. Gemeinhardt Miranda N. Limbach Thomas R. Gebhardt Clark W. Eriksson Shannon L. Eriksson Jacob R. Lindale Elysia A. Goodson Warren S. Warren Eduard Y. Chekmenev Boyd M. Goodson 《Angewandte Chemie (International ed. in English)》2020,59(1):418-423
Herein, we demonstrate “direct” 13C hyperpolarization of 13C‐acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir‐IMes; [IrCl(COD)(IMes)], (IMes=1,3‐bis(2,4,6‐trimethylphenyl), imidazole‐2‐ylidene; COD=cyclooctadiene)] was first activated in the presence of an auxiliary substrate (pyridine) in alcohol. Following addition of sodium 1‐13C‐acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions of SABRE in shield enables alignment transfer to heteronuclei, SABRE‐SHEATH) resulted in positive enhancements of up to ≈100‐fold in the 13C NMR signal compared to thermal equilibrium at 9.4 T. The present results are consistent with a mechanism of “direct” transfer of spin order from parahydrogen to 13C spins of acetate weakly bound to the catalyst, under conditions of fast exchange with respect to the 13C acetate resonance, but we find that relaxation dynamics at microtesla fields alter the optimal matching from the traditional SABRE‐SHEATH picture. Further development of this approach could lead to new ways to rapidly, cheaply, and simply hyperpolarize a broad range of substrates (e.g. metabolites with carboxyl groups) for various applications, including biomedical NMR and MRI of cellular and in vivo metabolism. 相似文献
8.
Dr. Ivan V. Skovpin Alexandra Svyatova Dr. Nikita Chukanov Prof. Dr. Eduard Y. Chekmenev Dr. Kirill V. Kovtunov Prof. Dr. Igor V. Koptyug 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(55):12694-12697
Signal Amplification by Reversible Exchange (SABRE) is a promising method for NMR signal enhancement and production of hyperpolarized molecules. As nuclear spin relaxation times of heteronuclei are usually much longer than those of protons, SABRE-based hyperpolarization of heteronuclei in molecules is highly important in the context of biomedical applications. In this work, we demonstrate that the SLIC-SABRE technique can be successfully used to hyperpolarize 15N nuclei in dalfampridine. The high polarization level of ca. 8 % achieved in this work made it possible to acquire 15N MR images at natural abundance of the 15N nuclei for the first time. 相似文献
9.
Single‐Scan Multidimensional NMR Analysis of Mixtures at Sub‐Millimolar Concentrations by using SABRE Hyperpolarization
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Dr. Valeria Daniele Dr. François‐Xavier Legrand Dr. Patrick Berthault Dr. Jean‐Nicolas Dumez Dr. Gaspard Huber 《Chemphyschem》2015,16(16):3413-3417
Signal amplification by reversible exchange (SABRE) is a promising method to increase the sensitivity of nuclear magnetic resonance (NMR) experiments. However, SABRE‐enhanced 1H NMR signals are short lived, and SABRE is often used to record 1D NMR spectra only. When the sample of interest is a complex mixture, this results in severe overlaps for 1H spectra. In addition, the use of a co‐substrate, whose signals may obscure the 1H spectra, is currently the most efficient way to lower the detection limit of SABRE experiments. Here, we describe an approach to obtain clean, SABRE‐hyperpolarized 2D 1H NMR spectra of mixtures of small molecules at sub‐millimolar concentrations in a single scan. The method relies on the use of para‐hydrogen together with a deuterated co‐substrate for hyperpolarization and ultrafast 2D NMR for acquisition. It is applicable to all substrates that can be polarized with SABRE. 相似文献
10.
Dr. Nikita V. Chukanov Dr. Oleg G. Salnikov Ivan A. Trofimov Mohammad S. H. Kabir Dr. Kirill V. Kovtunov Prof. Igor V. Koptyug Prof. Eduard Y. Chekmenev 《Chemphyschem》2021,22(10):960-967
Signal Amplification by Reversible Exchange (SABRE) technique enables nuclear spin hyperpolarization of wide range of compounds using parahydrogen. Here we present the synthetic approach to prepare 15N-labeled [15N]dalfampridine (4-amino[15N]pyridine) utilized as a drug to reduce the symptoms of multiple sclerosis. The synthesized compound was hyperpolarized using SABRE at microtesla magnetic fields (SABRE-SHEATH technique) with up to 2.0 % 15N polarization. The 7-hour-long activation of SABRE pre-catalyst [Ir(IMes)(COD)Cl] in the presence of [15N]dalfampridine can be remedied by the use of pyridine co-ligand for catalyst activation while retaining the 15N polarization levels of [15N]dalfampridine. The effects of experimental conditions such as polarization transfer magnetic field, temperature, concentration, parahydrogen flow rate and pressure on 15N polarization levels of free and equatorial catalyst-bound [15N]dalfampridine were investigated. Moreover, we studied 15N polarization build-up and decay at magnetic field of less than 0.04 μT as well as 15N polarization decay at the Earth's magnetic field and at 1.4 T. 相似文献
11.
Dr. Andrey N. Pravdivtsev Prof. Dr. Jan-Bernd Hövener 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(32):7659-7668
The hyperpolarization of nuclear spins by using parahydrogen (pH2) is a fascinating technique that allows spin polarization and thus the magnetic resonance signal to be increased by several orders of magnitude. Entirely new applications have become available. Signal amplification by reversible exchange (SABRE) is a relatively new method that is based on the reversible exchange of a substrate, catalyst and parahydrogen. SABRE is particularly interesting for in vivo medical and industrial applications, such as fast and low-cost trace analysis or continuous signal enhancement. Ever since its discovery, many attempts have been made to model and understand SABRE, with various degrees of simplifications. In this work, we reduced the simplifications further, taking into account non-linear chemical and physical (CAP) dynamics of several multi-spin systems. A master equation was derived and realized using the MOIN open-source software. The effects of different parameters (exchange rates, concentrations, spin–spin couplings) on relaxation and the polarization level have been evaluated and the results provide interesting insights into the mechanism of SABRE. 相似文献
12.
Dr. Peter J. Rayner Prof. Dr. Simon B. Duckett 《Angewandte Chemie (International ed. in English)》2018,57(23):6742-6753
Signal amplification by reversible exchange (SABRE) turns typically weak magnetic resonance responses into strong signals making previously impractical measurements possible. This technique has gained significant popularity because of its speed and simplicity. This Minireview tracks the development of SABRE from the initial hyperpolarization of pyridine in 2009 to the point in which 50 % 1H polarization levels have been achieved in a di‐deuterio‐nicotinate, a key step in the pathway to potential clinical use. Simple routes to highly efficient 15N hyperpolarization and the creation of hyperpolarized long‐lived magnetic states are illustrated. To conclude, we describe how the recently reported SABRE‐RELAY approach offers a route for parahydrogen to hyperpolarize a much wider array of molecular scaffolds, such as amides, alcohols, carboxylic acids, and phosphates, than was previously thought possible. We predict that collectively these developments ensure that SABRE will significantly impact on both chemical analysis and the diagnosis of disease in the future. 相似文献
13.
Dr. Alexey S. Kiryutin Prof. Alexandra V. Yurkovskaya Prof. Konstantin L. Ivanov 《Chemphyschem》2021,22(14):1470-1477
Signal Amplification By Reversible Exchange (SABRE) is gaining increased attention as a tool to enhance weak Nuclear Magnetic Resonance (NMR) signals. In SABRE, spin order is transferred from parahydrogen (H2 in its nuclear singlet spin state) to a substrate molecule in a transient Ir-based complex. In recent years, SABRE polarization of biologically active substrates has been demonstrated, notably of metronidazole – an antibiotic and antiprotozoal drug. In this work, we study 15N SABRE polarization of metronidazole at natural isotope abundance. We are able to demonstrate significant 15N polarization reaching 15 %, which corresponds to a signal enhancement of 46,000 at 9.4 T for the nitrogen atom with lone electron pair. Additionally, the other two N-atoms can be polarized, although less efficiently. We present a detailed study of the field dependence of polarization and explain the maxima in the field dependence using the concept of coherent polarization transfer at level anti-crossings in the SABRE complex. A study of spin relaxation phenomena presented here enables optimization of the magnetic field for efficient storage of non-thermal polarization. 相似文献
14.
Thomas B. R. Robertson Lysbeth H. Antonides Nicolas Gilbert Dr. Sophie L. Benjamin Dr. Stuart K. Langley Dr. Lindsey J. Munro Dr. Oliver B. Sutcliffe Dr. Ryan E. Mewis 《ChemistryOpen》2019,8(12):1375-1382
Fentanyl, also known as ‘jackpot’, is a synthetic opiate that is 50–100 times more potent than morphine. Clandestine laboratories produce analogues of fentanyl, known as fentalogues to circumvent legislation regarding its production. Three pyridyl fentalogues were synthesized and then hyperpolarized by signal amplification by reversible exchange (SABRE) to appraise the forensic potential of the technique. A maximum enhancement of -168-fold at 1.4 T was recorded for the ortho pyridyl 1H nuclei. Studies of the activation parameters for the three fentalogues revealed that the ratio of ligand loss trans to hydride and hydride loss in the complex [Ir(IMes)(L)3(H)2]+ (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene) ranged from 0.52 to 1.83. The fentalogue possessing the ratio closest to unity produced the largest enhancement subsequent to performing SABRE at earth's magnetic field. It was possible to hyperpolarize a pyridyl fentalogue selectively from a matrix that consisted largely of heroin (97 : 3 heroin:fentalogue) to validate the use of SABRE as a forensic tool. 相似文献
15.
Rational Design of [13C,D14]Tert‐butylbenzene as a Scaffold Structure for Designing Long‐lived Hyperpolarized 13C Probes
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Yuki Imakura Dr. Hiroshi Nonaka Dr. Yoichi Takakusagi Prof. Dr. Kazuhiro Ichikawa Nesmine R. Maptue Dr. Alexander M. Funk Prof. Dr. Chalermchai Khemtong Prof. Dr. Shinsuke Sando 《化学:亚洲杂志》2018,13(3):280-283
Dynamic nuclear polarization (DNP) is a technique to polarize the nuclear spin population. As a result of the hyperpolarization, the NMR sensitivity of the nuclei in molecules can be dramatically enhanced. Recent application of the hyperpolarization technique has led to advances in biochemical and molecular studies. A major problem is the short lifetime of the polarized nuclear spin state. Generally, in solution, the polarized nuclear spin state decays to a thermal spin equilibrium, resulting in loss of the enhanced NMR signal. This decay is correlated directly with the spin‐lattice relaxation time T1. Here we report [13C,D14]tert‐butylbenzene as a new scaffold structure for designing hyperpolarized 13C probes. Thanks to the minimized spin‐lattice relaxation (T1) pathways, its water‐soluble derivative showed a remarkably long 13C T1 value and long retention of the hyperpolarized spin state. 相似文献
16.
The 15NMR chemical shifts were measured of a number of N-substituted formamides and acetamides at the natural abundance level. The ratios of the cis and trans isomers for several N-alkylformamides were also determined. Substituent effects on the 15N chemical shifts of formamides are compared with those of some other nitrogen-containing compounds. There is a consistent pattern of behavior of the one bond spin–spin coupling constants [1J(15NH)] wherein the trans isomers of N-alkylformamides are larger than those of the cis isomers. 相似文献
17.
Zhenfeng Pang Hanxi Guan Lina Gao Weicheng Cao Jinglin Yin Xueqian Kong 《物理化学学报》2020,36(4):1906018-0
核磁共振(NMR)技术凭借其高空间分辨率,宽时间响应尺度和非侵入检测等特点,在化学分析和医疗诊断中发挥着重要的作用。但是原子核的低极化使现阶段NMR技术的灵敏度较低。超极化技术是一类可以有效提高NMR灵敏度的方法。其通过物理或化学过程把原子核自旋态推向一个偏离热力学平衡的状态,使NMR信号强度得到几个数量级的提升,极大地改善了灵敏度。多种超极化技术已经在各个领域崭露头角。本文用较为形象的描述对几种常见的超极化技术包括:动态核极化、光泵、光核极化、化学诱导动态核极化、仲氢诱导极化。从其精巧的原理和广泛的应用进行介绍,有助于人们对超极化技术的认知。 相似文献
18.
Derek R. Boyd Michael E. Stubbs N. J. Thompson Herman J. C. Yeh Donald M. Jerina Roderick E. Wasylishen 《Magnetic resonance in chemistry : MRC》1980,14(6):528-533
Nitrogen-15-hydrogen 2J(15NH), 15N, 13C 1J(15N13C) and 13C, H 1J(13CH) coupling constants have been measured and their signs determined for cis-and trans-[9-anthryl(13C)methylene](2H3)methylamine (15N)-oxide. Values of 2J(15NH) were of similar magnitude (~2 Hz) but were of opposite sign. The results are compared and contrasted with those reported for related imino and quaternary imino systems. Vicinal 3J(15NH) coupling constants have been measured in cis- and trans-15N-[1-(α-naphthyl)ethylidene]benzylamine and 15N-[1-(p-nitrophenyl)ethylidene]-t-butylamine and were found to be larger when the imino methyl group was cis to the nitrogen lone pair. The corresponding cis and trans ketonitrones formed by photoisomerization of the derived oxaziridines had 3J(15NH) values of c. 3.3 Hz. A study of the signs and magnitudes of observed and calculated 15N,H coupling constants for all of the 15N labelled imines, oxaziridines, imine N-oxides (nitrones) and similar model systems which were synthesized is described. 相似文献
19.
Prof. Dr. Vladimir V. Zhivonitko Henrik Beer Danila O. Zakharov Dr. Jonas Bresien Prof. Dr. Axel Schulz 《Chemphyschem》2021,22(9):813-817
Biradicaloids attract attention as a novel class of reagents that can activate small molecules such as H2, ethylene and CO2. Herein, we study activation of parahydrogen (nuclear spin-0 isomer of H2) by a number of 4- and 5-membered pnictogen biradicaloids based on hetero-cyclobutanediyl [X(μ-NTer)2Z] and hetero-cyclopentanediyl [X(μ-NTer)2ZC(NDmp)] moieties (X,Z=P,As; Ter=2,6-Mes2−C6H3, Dmp=2,6-Me2−C6H3). The concerted mechanism of this reaction allowed observing strong nuclear spin hyperpolarization effects in 1H and 31P NMR experiments. Signal enhancements from two to four orders of magnitude were detected at 9.4 T depending on the structure. It is demonstrated that 4-membered biradicaloids activate H2 reversibly, leading to SABRE (signal amplification by reversible exchange) hyperpolarization of biradicaloids themselves and their H2 adducts. In contrast, the 5-membered counterparts demonstrate rather irreversible parahydrogen activation resulting in hyperpolarized H2 adducts only. Kinetic measurements provided parameters to support experimental observations. 相似文献
20.
Andrey N. Pravdivtsev Prof. Alexandra V. Yurkovskaya Prof. Hans‐Martin Vieth Dr. Konstantin L. Ivanov Prof. Robert Kaptein 《Chemphyschem》2013,14(14):3327-3331
Various hyperpolarization methods are able to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) by several orders of magnitude. Among these methods are para‐hydrogen‐induced polarization (PHIP) and signal amplification by reversible exchange (SABRE), which exploit the strong nuclear alignment of para‐hydrogen. Several SABRE experiments have been reported but, so far, it has not been possible to account for the experimentally observed sign and magnetic‐field dependence of substrate polarization. Herein, we present an analysis based on level anti‐crossings (LACs), which provides a complete understanding of the SABRE effect. The field‐dependence of both net and anti‐phase polarization is measured for several ligands, which can be reproduced by the theory. The similar SABRE field‐dependence for different ligands is also explained. In general, the LAC concept allows complex spin dynamics to be unraveled, and is crucial for optimizing the performance of novel hyperpolarization methods in NMR and MRI techniques. 相似文献