1
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Martin RM, Diaz S, Poncelet M, Driesschaert B, Barth E, Kotecha M, Epel B, Eaton GR, Biller JR. Toward a Nanoencapsulated EPR Imaging Agent for Clinical Use. Mol Imaging Biol 2023:10.1007/s11307-023-01863-0. [PMID: 37870648 PMCID: PMC11035482 DOI: 10.1007/s11307-023-01863-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/24/2023]
Abstract
PURPOSE Progress toward developing a novel radiocontrast agent for determining pO2 in tumors in a clinical setting is described. The imaging agent is designed for use with electron paramagnetic resonance imaging (EPRI), in which the collision of a paramagnetic probe molecule with molecular oxygen causes a spectroscopic change which can be calibrated to give the real oxygen concentration in the tumor tissue. PROCEDURES The imaging agent is based on a nanoscaffold of aluminum hydroxide (boehmite) with sizes from 100 to 200 nm, paramagnetic probe molecule, and encapsulation with a gas permeable, thin (10-20 nm) polymer layer to separate the imaging agent and body environment while still allowing O2 to interact with the paramagnetic probe. A specially designed deuterated Finland trityl (dFT) is covalently attached on the surface of the nanoparticle through 1,3-dipolar addition of the alkyne on the dFT with an azide on the surface of the nanoscaffold. This click-chemistry reaction affords 100% efficiency of the trityl attachment as followed by the complete disappearance of the azide peak in the infrared spectrum. The fully encapsulated, dFT-functionalized nanoparticle is referred to as RADI-Sense. RESULTS Side-by-side in vivo imaging comparisons made in a mouse model made between RADI-Sense and free paramagnetic probe (OX-071) showed oxygen sensitivity is retained and RADI-Sense can create 3D pO2 maps of solid tumors CONCLUSIONS: A novel encapsulated nanoparticle EPR imaging agent has been described which could be used in the future to bring EPR imaging for guidance of radiotherapy into clinical reality.
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Affiliation(s)
| | | | - Martin Poncelet
- Department of Pharmaceutical Sciences, School of Pharmacy & In-Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
| | - Benoit Driesschaert
- Department of Pharmaceutical Sciences, School of Pharmacy & In-Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
| | - Eugene Barth
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, 60637, USA
| | | | - Boris Epel
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, 60637, USA
- Oxygen Measurement Core, O2M Technologies, Chicago, IL, 60612, USA
| | - Gareth R Eaton
- Department of Chemistry, University of Denver, Denver, CO, 80210, USA
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2
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Grazia Concilio M, Frydman L. Steady state effects introduced by local relaxation modes on J-driven DNP-enhanced NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 355:107542. [PMID: 37672989 DOI: 10.1016/j.jmr.2023.107542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/03/2023] [Accepted: 08/26/2023] [Indexed: 09/08/2023]
Abstract
One of solution-state Nuclear Magnetic Resonance (NMR)'s main weaknesses, is its relative insensitivity. J-driven Dynamic Nuclear Polarization (JDNP) was recently proposed for enhancing solution-state NMR's sensitivity, by bypassing the limitations faced by conventional Overhauser DNP (ODNP), at the high magnetic fields where most analytical research is performed. By relying on biradicals with inter-electron exchange couplings Jex on the order of the electron Larmor frequency ωE, JDNP was predicted to introduce a transient enhancement in NMR's nuclear polarization at high magnetic fields, and for a wide range of rotational correlation times of medium-sized molecules in conventional solvents. This communication revisits the JDNP proposal, including additional effects and conditions that were not considered in the original treatment. These include relaxation mechanisms arising from local vibrational modes that often dominate electron relaxation in organic radicals, as well as the possibility of using biradicals with Jex of the order of the nuclear Larmor frequency ωN as potential polarizing agents. The presence of these new relaxation effects lead to variations in the JDNP polarization mechanism originally proposed, and indicate that triplet-to-singlet cross-relaxation processes may lead to a nuclear polarization enhancement that persists even at steady states. The physics and potential limitations of the ensuing theoretical derivations, are briefly discussed.
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Affiliation(s)
- Maria Grazia Concilio
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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3
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Abdullin D, Hett T, Fleck N, Kopp K, Cassidy S, Richert S, Schiemann O. Magneto-Structural Correlations in a Mixed Porphyrin(Cu 2+ )/Trityl Spin System: Magnitude, Sign, and Distribution of the Exchange Coupling Constant. Chemistry 2023; 29:e202203148. [PMID: 36519664 DOI: 10.1002/chem.202203148] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Tetrathiatriarylmethyl radicals (TAM or trityl) are receiving increasing attention in various fields of magnetic resonance such as imaging, dynamic nuclear polarization, spin labeling, and, more recently, molecular magnetism and quantum information technology. Here, a trityl radical attached via a phenyl bridge to a copper(II)tetraphenylporphyrin was synthesized, and its magnetic properties studied by multi-frequency continuous-wave electron paramagnetic resonance (EPR) spectroscopy and magnetic measurements. EPR revealed that the electron spin-spin coupling constant J between the trityl and Cu2+ spin centers is ferromagnetic with a magnitude of -2.3 GHz (-0.077 cm-1 , + J S → 1 S → 2 ${+J{\vec{S}}_{1}{\vec{S}}_{2}}$ convention) and a distribution width of 1.2 GHz (0.040 cm-1 ). With the help of density functional theory (DFT) calculations, the obtained ferromagnetic exchange coupling, which is unusual for para-substituted phenyl-bridged biradicals, could be related to the almost perpendicular orientation of the phenyl linker with respect to the porphyrin and trityl ring planes in the energy minimum, while the J distribution was rationalized by the temperature weighted rotation of the phenyl bridge about the molecular axis connecting both spin centers. This study exemplifies the importance of molecular dynamics for the homogeneity (or heterogeneity) of the magnetic properties of trityl-based systems.
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Affiliation(s)
- Dinar Abdullin
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Tobias Hett
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Nico Fleck
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany.,Merck KGaA, Q20/001, Frankfurterstr. 250, 64293, Darmstadt, Germany
| | - Kevin Kopp
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Simon Cassidy
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Olav Schiemann
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115, Bonn, Germany.,Department of Chemical and Biological Physics, Weizmann Institute of Science, 761001, Rehovot, Israel
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4
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Concilio MG, Frydman L. Microwave-free J-driven dynamic nuclear polarization: A proposal for enhancing the sensitivity of solution-state NMR. Phys Rev E 2023; 107:035303. [PMID: 37073023 DOI: 10.1103/physreve.107.035303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 02/16/2023] [Indexed: 04/20/2023]
Abstract
J-driven dynamic nuclear polarization (JDNP) was recently proposed for enhancing the sensitivity of solution-state nuclear magnetic resonance (NMR), while bypassing the limitations faced by conventional (Overhauser) DNP at magnetic fields of interest in analytical applications. Like Overhauser DNP, JDNP also requires saturating the electronic polarization using high-frequency microwaves known to have poor penetration and associated heating effects in most liquids. The present microwave-free JDNP (MF-JDNP) proposal seeks to enhance solution NMR's sensitivity by shuttling the sample between higher and lower magnetic fields, with one of these fields providing an electron Larmor frequency that matches the interelectron exchange coupling J_{ex}. If spins cross this so-called JDNP condition sufficiently fast, we predict that a sizable nuclear polarization will be created without microwave irradiation. This MF-JDNP proposal requires radicals whose singlet-triplet self-relaxation rates are dominated by dipolar hyperfine relaxation, and shuttling times that can compete with these electron relaxation processes. This paper discusses the theory behind the MF-JDNP, as well as proposals for radicals and conditions that could enable this new approach to NMR sensitivity enhancement.
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Affiliation(s)
- Maria Grazia Concilio
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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5
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Concilio MG, Kuprov I, Frydman L. J-Driven dynamic nuclear polarization for sensitizing high field solution state NMR. Phys Chem Chem Phys 2022; 24:2118-2125. [PMID: 35024715 DOI: 10.1039/d1cp04186j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dynamic nuclear polarization (DNP) is widely used to enhance solid state nuclear magnetic resonance (NMR) sensitivity. Its efficiency as a generic signal-enhancing approach for liquid state NMR, however, decays rapidly with magnetic field B0, unless mediated by scalar interactions arising only in exceptional cases. This has prevented a more widespread use of DNP in structural and dynamical solution NMR analyses. This study introduces a potential solution to this problem, relying on biradicals with exchange couplings Jex of the order of the electron Larmor frequency ωE. Numerical and analytical calculations show that in such Jex ≈ ±ωE cases a phenomenon akin to that occurring in chemically induced DNP (CIDNP) happens, leading to different relaxation rates for the biradical singlet and triplet states which are hyperfine-coupled to the nuclear α or β states. Microwave irradiation can then generate a transient nuclear polarization build-up with high efficiency, at all magnetic fields that are relevant in contemporary NMR, and for all rotational diffusion correlation times that occur in small- and medium-sized molecules in conventional solvents.
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Affiliation(s)
- Maria Grazia Concilio
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
| | - Ilya Kuprov
- School of Chemistry, University of Southampton, Southampton, UK
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel. .,National High Magnetic Field Laboratory, Tallahassee, Florida, USA
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6
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Sannikova N, Timofeev I, Bagryanskaya E, Bowman M, Fedin M, Krumkacheva O. Electron Spin Relaxation of Photoexcited Porphyrin in Water-Glycerol Glass. Molecules 2020; 25:E2677. [PMID: 32527023 PMCID: PMC7321249 DOI: 10.3390/molecules25112677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/05/2020] [Accepted: 06/06/2020] [Indexed: 02/07/2023] Open
Abstract
Recently, the photoexcited triplet state of porphyrin was proposed as a promising spin-label for pulsed dipolar electron paramagnetic resonance (EPR). Herein, we report the factors that determine the electron spin echo dephasing of the photoexcited porphyrin in a water-glycerol matrix. The electron spin relaxation of a water-soluble porphyrin was measured by Q-band EPR, and the temperature dependence and the effect of solvent deuteration on the relaxation times were studied. The phase memory relaxation rate (1/Tm) is noticeably affected by solvent nuclei and is substantially faster in protonated solvents than in deuterated solvents. The Tm is as large as 13-17 μs in deuterated solvent, potentially expanding the range of distances available for measurement by dipole spectroscopy with photoexcited porphyrin. The 1/Tm depends linearly on the degree of solvent deuteration and can be used to probe the environment of a porphyrin in or near a biopolymer, including the solvent accessibility of porphyrins used in photodynamic therapy. We characterized the noncovalent binding of porphyrin to human serum albumin (HSA) from 1/Tm and electron spin echo envelope modulation (ESEEM) and found that porphyrin is quite exposed to solvent on the surface of HSA. The 1/Tm and ESEEM are equally effective and provide complementary methods to determine the solvent accessibility of a porphyrin bound to protein or to determine the location of the porphyrin.
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Affiliation(s)
- Natalya Sannikova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Ivan Timofeev
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Elena Bagryanskaya
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Michael Bowman
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, AL 35487-0336, USA
| | - Matvey Fedin
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Olesya Krumkacheva
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
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7
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Kveder M, Rakvin B, You J. A quantum many body model for the embedded electron spin decoherence in organic solids. J Chem Phys 2019; 151:164124. [DOI: 10.1063/1.5124561] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Marina Kveder
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Boris Rakvin
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Jiangyang You
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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8
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Ngendahimana T, Ayikpoe R, Latham JA, Eaton GR, Eaton SS. Structural insights for vanadium catecholates and iron‑sulfur clusters obtained from multiple data analysis methods applied to electron spin relaxation data. J Inorg Biochem 2019; 201:110806. [PMID: 31505439 DOI: 10.1016/j.jinorgbio.2019.110806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/06/2019] [Accepted: 08/21/2019] [Indexed: 01/22/2023]
Abstract
Electron paramagnetic resonance (EPR) inversion recovery curves for vanadium catecholates and iron‑sulfur clusters were analyzed with three models: the sum of two exponentials, a stretched exponential, and a model-free distribution of exponentials (UPEN). For all data sets studied fits with a stretched exponential were statistically indistinguishable from the sum of two exponentials, and were significantly better than for single exponentials. UPEN provides insights into the structures of the distributions. For a vanadium(IV) tris catecholate the distribution of relaxation rates calculated with UPEN shows the contribution from spectral diffusion at low temperatures. The energy of the local mode for this complex, found from the temperature dependence of the spin lattice relaxation, is consistent with values expected for a metal-ligand vibration. For the [2Fe-2S]+ cluster in pyruvate formate lyase activating enzyme (PFL-AE) the small stretched exponential β values (0.3) at low temperature and the distributions calculated with UPEN reflect the contribution from a second rapidly relaxing species that could be difficult to detect by continuous wave EPR. The distributions in 1/T1 for the [4Fe-4S]+ clusters in Mycofactocin maturase were about a factor of four wider than for the three other systems studied. The very broad distribution of relaxation rates may be due to protein mobility and distributions in electronic energies and local environments for the clusters. UPEN provides insight into several situations that can result in low values of stretch parameter β including contributions from spectral diffusion, overlapping signals from distinguishable clusters, or very wide distributions.
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Affiliation(s)
- Thacien Ngendahimana
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Richard Ayikpoe
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - John A Latham
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America..
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9
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Krumkacheva OA, Timofeev IO, Politanskaya LV, Polienko YF, Tretyakov EV, Rogozhnikova OY, Trukhin DV, Tormyshev VM, Chubarov AS, Bagryanskaya EG, Fedin MV. Triplet Fullerenes as Prospective Spin Labels for Nanoscale Distance Measurements by Pulsed Dipolar EPR Spectroscopy. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Olesya A. Krumkacheva
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Ivan O. Timofeev
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Larisa V. Politanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Yuliya F. Polienko
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Evgeny V. Tretyakov
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Olga Yu. Rogozhnikova
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Dmitry V. Trukhin
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Victor M. Tormyshev
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Alexey S. Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Elena G. Bagryanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Matvey V. Fedin
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
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10
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Krumkacheva OA, Timofeev IO, Politanskaya LV, Polienko YF, Tretyakov EV, Rogozhnikova OY, Trukhin DV, Tormyshev VM, Chubarov AS, Bagryanskaya EG, Fedin MV. Triplet Fullerenes as Prospective Spin Labels for Nanoscale Distance Measurements by Pulsed Dipolar EPR Spectroscopy. Angew Chem Int Ed Engl 2019; 58:13271-13275. [PMID: 31322814 DOI: 10.1002/anie.201904152] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/11/2019] [Indexed: 11/11/2022]
Abstract
Precise nanoscale distance measurements by pulsed electron paramagnetic resonance (EPR) spectroscopy play a crucial role in structural studies of biomolecules. The properties of the spin labels used in this approach determine the sensitivity limits, attainable distances, and proximity to biological conditions. Herein, we propose and validate the use of photoexcited fullerenes as spin labels for pulsed dipolar (PD) EPR distance measurements. Hyperpolarization and the narrower spectrum of fullerenes compared to other triplets (e.g., porphyrins) boost the sensitivity, and superior relaxation properties allow PD EPR measurements up to a near-room temperature. This approach is demonstrated using fullerene-nitroxide and fullerene-triarylmethyl pairs, as well as a supramolecular complex of fullerene with nitroxide-labeled protein. Photoexcited triplet fullerenes can be considered as new spin labels with outstanding spectroscopic properties for future structural studies of biomolecules.
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Affiliation(s)
- Olesya A Krumkacheva
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Ivan O Timofeev
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Larisa V Politanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Yuliya F Polienko
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Evgeny V Tretyakov
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Olga Yu Rogozhnikova
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Dmitry V Trukhin
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Victor M Tormyshev
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Alexey S Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Elena G Bagryanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Matvey V Fedin
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
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11
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Qu Y, Li Y, Tan X, Zhai W, Han G, Hou J, Liu G, Song Y, Liu Y. Synthesis and Characterization of Hydrophilic Trityl Radical TFO for Biomedical and Biophysical Applications. Chemistry 2019; 25:7888-7895. [PMID: 30972843 DOI: 10.1002/chem.201900262] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Indexed: 12/18/2022]
Abstract
Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications as spin probes/labels for EPR spectroscopy and imaging, and as polarizing agents for dynamic nuclear polarization. The high hydrophilicity of TAM radicals is essential for their biomedical applications. However, the synthesis of hydrophilic TAM radicals (e.g., OX063) is extremely challenging and has only been reported in the patent literature, to date. Herein, an efficient synthesis of a highly water-soluble TAM radical bis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']bis([1,3]dithiol-4-yl)-mono-(8-carboxyl-2,2,6,6-tetrakis(2-hydroxyethyl)benzo[1,2-d:4,5-d']bis([1,3]dithiol-4-yl)methyl (TFO), which contains four additional hydroxylethyl groups, relative to the Finland trityl radical CT-03, is reported. Similar to OX063, TFO exhibits excellent properties, including high water solubility in phosphate buffer, low log P, low pKa , long relaxation times, and negligible binding with bovine serum albumin. On the other hand, TFO has a sharper EPR line and higher O2 sensitivity than those of OX063. Therefore, in combination with its facile synthesis, TFO should find wide applications in magnetic resonance related fields and this synthetic approach would shed new light on the synthesis of other hydrophilic TAM radicals.
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Affiliation(s)
- Yuying Qu
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Yingchun Li
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Xiaoli Tan
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Weixiang Zhai
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Guifang Han
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Jingli Hou
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Guoquan Liu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Beijing, 100191, P.R. China
| | - Yuguang Song
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling, Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P.R. China
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12
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Hintz H, Vanas A, Klose D, Jeschke G, Godt A. Trityl Radicals with a Combination of the Orthogonal Functional Groups Ethyne and Carboxyl: Synthesis without a Statistical Step and EPR Characterization. J Org Chem 2019; 84:3304-3320. [DOI: 10.1021/acs.joc.8b03234] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Henrik Hintz
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Agathe Vanas
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Daniel Klose
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
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Kishimoto S, Krishna MC, Khramtsov VV, Utsumi H, Lurie DJ. In Vivo Application of Proton-Electron Double-Resonance Imaging. Antioxid Redox Signal 2018; 28:1345-1364. [PMID: 28990406 PMCID: PMC5910041 DOI: 10.1089/ars.2017.7341] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 10/05/2017] [Indexed: 01/01/2023]
Abstract
SIGNIFICANCE Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO2), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH+ forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. CRITICAL ISSUES High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. FUTURE DIRECTIONS PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345-1364.
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Affiliation(s)
- Shun Kishimoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Murali C. Krishna
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Valery V. Khramtsov
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia
| | - Hideo Utsumi
- School of Pharmaceutical Sciences, The University of Shizuoka, Shizuoka, Japan
| | - David J. Lurie
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
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Kuzhelev AA, Krumkacheva OA, Shevelev GY, Yulikov M, Fedin MV, Bagryanskaya EG. Room-temperature distance measurements using RIDME and the orthogonal spin labels trityl/nitroxide. Phys Chem Chem Phys 2018; 20:10224-10230. [PMID: 29594278 DOI: 10.1039/c8cp01093e] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron paramagnetic resonance (EPR) based nanometer distance measurements at ambient temperatures are of particular interest for structural biology applications. The nitroxide spin labels commonly used in EPR reveal relatively short transverse relaxation under these conditions, which limits their use for detecting static dipolar interactions. At the same time, the longitudinal relaxation of nitroxide spin labels is still long enough to allow using them as 'pumped' species in the relaxation induced dipolar modulation enhancement (RIDME) experiment where the detection is carried out on the slower relaxing triarylmethyl (TAM) spin labels. In the present study, we report the first demonstration of room-temperature RIDME distance measurements in nucleic acids using TAM as the slow-relaxing detected species and traditional nitroxide as the fast-relaxing partner spin. Two types of immobilizers, glassy trehalose and the modified silica gel Nucleosil, were used for immobilization of the spin-labeled biomolecules. The room-temperature RIDME-based distance distributions are in good agreement with those measured at 80 K by other techniques. Room-temperature RIDME on the spin pairs trityl/nitroxide may become a useful method for the structural characterization of biomacromolecules and biomolecular complexes at near physiological temperatures.
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Affiliation(s)
- Andrey A Kuzhelev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.
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15
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Matsumoto KI, Kishimoto S, Devasahayam N, Chandramouli GVR, Ogawa Y, Matsumoto S, Krishna MC, Subramanian S. EPR-based oximetric imaging: a combination of single point-based spatial encoding and T 1 weighting. Magn Reson Med 2018; 80:2275-2287. [PMID: 29582458 DOI: 10.1002/mrm.27182] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/07/2018] [Accepted: 02/23/2018] [Indexed: 01/14/2023]
Abstract
PURPOSE Spin-lattice relaxation rate (R1 )-based time-domain EPR oximetry is reported for in vivo applications using a paramagnetic probe, a trityl-based Oxo71. METHODS The R1 dependence of the trityl probe Oxo71 on partial oxygen pressure (pO2 ) was assessed using single-point imaging mode of spatial encoding combined with rapid repetition, similar to T1 -weighted MRI, for which R1 was determined from 22 repetition times ranging from 2.1 to 40.0 μs at 300 MHz. The pO2 maps of a phantom with 3 tubes containing 2 mM Oxo71 solutions equilibrated at 0%, 2%, and 5% oxygen were determined by R1 and apparent spin-spin relaxation rate ( R2*) simultaneously. RESULTS The pO2 maps derived from R1 and R2* agreed with the known pO2 levels in the tubes of Oxo71. However, the histograms of pO2 revealed that R1 offers better pO2 resolution than R2* in low pO2 regions. The SDs of pixels at 2% pO2 (15.2 mmHg) were about 5 times lower in R1 -based estimation than R2*-based estimation (mean ± SD: 13.9 ± 1.77 mmHg and 18.3 ± 8.70 mmHg, respectively). The in vivo pO2 map obtained from R1 -based assessment displayed a homogeneous profile in low pO2 regions in tumor xenografts, consistent with previous reports on R2*-based oximetric imaging. The scan time to obtain the R1 map can be significantly reduced using 3 repetition times ranging from 4.0 to 12.0 μs. CONCLUSION Using the single-point imaging modality, R1 -based oximetry imaging with useful spatial and oxygen resolutions for small animals was demonstrated.
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Affiliation(s)
- Ken-Ichiro Matsumoto
- Quantitative RedOx Sensing Team, Department of Basic Medical Sciences for Radiation Damage, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
- Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan
| | | | | | | | - Yukihiro Ogawa
- Quantitative RedOx Sensing Team, Department of Basic Medical Sciences for Radiation Damage, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
- Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan
| | - Shingo Matsumoto
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
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16
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Elewa M, Maltar-Strmečki N, Said MM, El Shihawy HA, El-Sadek M, Frank J, Drescher S, Drescher M, Mäder K, Hinderberger D, Imming P. Synthesis and EPR-spectroscopic characterization of the perchlorotriarylmethyl tricarboxylic acid radical (PTMTC) and its 13C labelled analogue (13C-PTMTC). Phys Chem Chem Phys 2018; 19:6688-6697. [PMID: 28210718 DOI: 10.1039/c6cp07200c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A hydrophilic tris(tetrachlorotriaryl)methyl (tetrachloro-TAM) radical labelled 50% with 13C at the central carbon atom was prepared. The mixture of isotopologue radicals was characterised by continuous wave and pulsed X-band electron paramagnetic spectroscopy (EPS). For the pharmaceutical and medical applications planned, the quantitative influence of oxygen, viscosity, temperature and pH on EPR line widths was studied in aqueous buffer, DMSO, water-methanol and water-glycerol mixtures. Under in vivo conditions, pH can be disregarded. There is a clear oxygen dependence of the width of the 12C isotopologue single EPR line in aqueous solutions while changes in rotational motion (viscosity) are observable only in the doublet lines of the central carbon of the 13C isotopologue. The tetrachloro-TAM proved to be very stable as a solid. Its thermal decay was determined quantitatively by thermal annealing. Towards ascorbic acid as a reducing agent and towards an oocyte cell extract it had a half-life of approx. 60 and 10 min. Thus for in vivo applications, 50% 13C tetrachloro-TAMs are suitable for selective and simultaneous oxygen and macroviscosity measurements in a formulation, e.g. nanocapsules.
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Affiliation(s)
- Marwa Elewa
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. and Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | - Nadica Maltar-Strmečki
- Institut für Chemie, Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle, Germany.
| | - Mohamed M Said
- Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | | | | | - Juliane Frank
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
| | - Simon Drescher
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Karsten Mäder
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
| | - Dariush Hinderberger
- Institut für Chemie, Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle, Germany.
| | - Peter Imming
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany.
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17
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Kuzhelev A, Akhmetzyanov D, Denysenkov V, Shevelev G, Krumkacheva O, Bagryanskaya E, Prisner T. High-frequency pulsed electron–electron double resonance spectroscopy on DNA duplexes using trityl tags and shaped microwave pulses. Phys Chem Chem Phys 2018; 20:26140-26144. [DOI: 10.1039/c8cp03951h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Distances between trityl spin labels attached to DNA duplexes were determined by 180 GHz and 260 GHz PELDOR spectroscopy applying broadband pump pulse at higher frequency.
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Affiliation(s)
- A. Kuzhelev
- Novosibirsk State University
- 630090 Novosibirsk
- Russia
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- 630090 Novosibirsk
| | - D. Akhmetzyanov
- Goethe University Frankfurt am Main
- Institute of Physical and Theoretical Chemistry
- Center for Biomolecular Magnetic Resonance
- 60438 Frankfurt am Main
- Germany
| | - V. Denysenkov
- Goethe University Frankfurt am Main
- Institute of Physical and Theoretical Chemistry
- Center for Biomolecular Magnetic Resonance
- 60438 Frankfurt am Main
- Germany
| | - G. Shevelev
- Novosibirsk State University
- 630090 Novosibirsk
- Russia
- Institute of Chemical Biology and Fundamental Medicine SB RAS
- 630090 Novosibirsk
| | - O. Krumkacheva
- Novosibirsk State University
- 630090 Novosibirsk
- Russia
- International Tomography Center SB RAS
- Novosibirsk
| | - E. Bagryanskaya
- Novosibirsk State University
- 630090 Novosibirsk
- Russia
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- 630090 Novosibirsk
| | - T. Prisner
- Goethe University Frankfurt am Main
- Institute of Physical and Theoretical Chemistry
- Center for Biomolecular Magnetic Resonance
- 60438 Frankfurt am Main
- Germany
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18
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Krumkacheva O, Bagryanskaya E. EPR-based distance measurements at ambient temperature. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:117-126. [PMID: 28579097 DOI: 10.1016/j.jmr.2017.02.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 05/24/2023]
Abstract
Pulsed dipolar (PD) EPR spectroscopy is a powerful technique allowing for distance measurements between spin labels in the range of 2.5-10.0nm. It was proposed more than 30years ago, and nowadays is widely used in biophysics and materials science. Until recently, PD EPR experiments were limited to cryogenic temperatures (T<80K). Recently, application of spin labels with long electron spin dephasing time at room temperature such as triarylmethyl radicals and nitroxides with bulky substituents at a position close to radical centers enabled measurements at room temperature and even at physiologically relevant temperatures by PD EPR as well as other approaches based on EPR (e.g., relaxation enhancement; RE). In this paper, we review the features of PD EPR and RE at ambient temperatures, in particular, requirements on electron spin phase memory time, ways of immobilization of biomolecules, the influence of a linker between the spin probe and biomolecule, and future opportunities.
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Affiliation(s)
- Olesya Krumkacheva
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Pr. Lavrentjeva 9, Novosibirsk 630090, Russian Federation; Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russian Federation; International Tomography Center SB RAS, Institutskaya 3A, Novosibirsk 630090, Russian Federation.
| | - Elena Bagryanskaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Pr. Lavrentjeva 9, Novosibirsk 630090, Russian Federation; Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russian Federation.
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19
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Kuzhelev AA, Tormyshev VM, Rogozhnikova OY, Trukhin DV, Troitskaya TI, Strizhakov RK, Krumkacheva OA, Fedin MV, Bagryanskaya EG. Triarylmethyl Radicals: EPR Study of 13C Hyperfine Coupling Constants. Z PHYS CHEM 2017; 231:777-794. [PMID: 28539703 PMCID: PMC5439964 DOI: 10.1515/zpch-2016-0811] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Triarylmethyl (TAM) radicals are widely used in Electron Paramagnetic Resonance (EPR) spectroscopy as spin labels and in EPR imaging as spin probes for in vivo oxymetry. One of the key advantages of TAMs is extremely narrow EPR line, especially in case of deuterated analogues (~5 μT). Another advantage is their slow spin relaxation even at physiological temperatures allowing, in particular, application of pulsed dipolar EPR methods for distance measurements in biomolecules. In this paper a large series of TAM radicals and their deuterated analogues is synthesized, and corresponding spectroscopic parameters including 13C hyperfine constants are obtained for the first time. The negligible dependence of 13C hyperfine constants on solvent, as well as on structure and number of substituents at para-C atoms of aromatic rings, has been found. In addition, we have demonstrated that 13C signals at natural abundance can be employed for successful room-temperature distance measurements using Pulsed Electron Double Resonance (PELDOR or DEER).
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Affiliation(s)
- Andrey A. Kuzhelev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Victor M. Tormyshev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Olga Yu. Rogozhnikova
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Dmitry V. Trukhin
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Tatiana I. Troitskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Rodion K. Strizhakov
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
| | - Olesya A. Krumkacheva
- International Tomography Center SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Matvey V. Fedin
- International Tomography Center SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Elena G. Bagryanskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
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20
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Eaton SS, Huber K, Elajaili H, McPeak J, Eaton GR, Longobardi LE, Stephan DW. Electron spin relaxation of a boron-containing heterocyclic radical. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 276:7-13. [PMID: 28081476 DOI: 10.1016/j.jmr.2016.12.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 12/23/2016] [Accepted: 12/24/2016] [Indexed: 06/06/2023]
Abstract
Preparation of the stable boron-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), by frustrated Lewis pair chemistry has been reported recently. Electron paramagnetic resonance measurements of this radical were made at X-band in toluene:dichloromethane (9:1) from 10 to 293K, in toluene from 180 to 293K and at Q-band at 80K. In well-deoxygenated 0.1mM toluene solution at room temperature hyperfine splittings from 11B, four pairs of 1H, and 5 pairs of 19F contribute to an EPR spectrum with many resolved lines. Observed hyperfine couplings were assigned based on DFT calculations and account for all of the fluorines and protons in the molecule. Rigid lattice g values are gx=2.0053, gy=2.0044, and gz=2.0028. Near the melting point of the solvent 1/Tm is enhanced due to motional averaging of g and A anisotropy. Increasing motion above the melting point enhances 1/T1 due to contributions from tumbling-dependent processes. The overall temperature dependence of 1/T1 from 10 to 293K was modeled with the sum of contributions of a process that is linear in T, a Raman process, spin rotation, and modulation of g anisotropy by molecular tumbling. The EPR measurements are consistent with the description of this compound as a substituted aromatic radical, with relatively small spin density on the boron.
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Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Kirby Huber
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Hanan Elajaili
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Joseph McPeak
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA.
| | | | - Douglas W Stephan
- University of Toronto, 80 St. George St, Toronto, ON M5S 3H6, Canada
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21
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Shi Y, Quine RW, Rinard GA, Buchanan L, Eaton SS, Eaton GR, Epel B, Seagle SW, Halpern HJ. Triarylmethyl Radical: EPR Signal to Noise at Frequencies between 250 MHz and 1.5 GHz and Dependence of Relaxation on Radical and Salt Concentration and on Frequency. ACTA ACUST UNITED AC 2016; 231:923-937. [PMID: 28392627 DOI: 10.1515/zpch-2016-0813] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In vivo oximetry by pulsed electron paramagnetic resonance is based on measurements of changes in electron spin relaxation rates of probe molecules, such as the triarylmethyl radicals. A series of experiments was performed at frequencies between 250 MHz and 1.5 GHz to assist in the selection of an optimum frequency for oximetry. Electron spin relaxation rates for the triarylmethyl radical OX063 as a function of radical concentration, salt concentration, and resonance frequency were measured by electron spin echo 2-pulse decay and 3-pulse inversion recovery in the frequency range of 250 MHz-1.5 GHz. At constant OX063 concentration, 1/T1 decreases with increasing frequency because the tumbling dependent processes that dominate relaxation at 250 MHz are less effective at higher frequency. 1/T2 also decreases with increasing frequency because 1/T1 is a significant contribution to 1/T2 for trityl radicals in fluid solution. 1/T2-1/T1, the incomplete motional averaging contribution to 1/T2, increases with increasing frequency. At constant frequency, relaxation rates increase with increasing radical concentration due to contributions from collisions that are more effective for 1/T2 than 1/T1. The collisional contribution to relaxation increases as the concentration of counter-ions in solution increases, which is attributed to interactions of cations with the negatively charged radicals that decrease repulsion between trityl radicals. The Signal-to-Noise ratio (S/N) of field-swept echo-detected spectra of OX063 were measured in the frequency range of 400 MHz-1 GHz. S/N values, normalized by √Q, increase as frequency increases. Adding salt to the radical solution decreased S/N because salt lowers the resonator Q. Changing the temperature from 19 to 37 °C caused little change in S/N at 700 MHz. Both slower relaxation rates and higher S/N at higher frequencies are advantageous for oximetry. The potential disadvantage of higher frequencies is the decreased depth of penetration into tissue.
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Affiliation(s)
- Yilin Shi
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - Richard W Quine
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - George A Rinard
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - Laura Buchanan
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - Gareth R Eaton
- Gareth R. Eaton, Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, USA
| | - Boris Epel
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Simone Wanless Seagle
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
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22
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Chen H, Maryasov AG, Rogozhnikova OY, Trukhin DV, Tormyshev VM, Bowman MK. Electron spin dynamics and spin-lattice relaxation of trityl radicals in frozen solutions. Phys Chem Chem Phys 2016; 18:24954-65. [PMID: 27560644 PMCID: PMC5482570 DOI: 10.1039/c6cp02649d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron spin-lattice relaxation of two trityl radicals, d24-OX063 and Finland trityl, were studied under conditions relevant to their use in dissolution dynamic nuclear polarization (DNP). The dependence of relaxation kinetics on temperature up to 100 K and on concentration up to 60 mM was obtained at X- and W-bands (0.35 and 3.5 Tesla, respectively). The relaxation is quite similar at both bands and for both trityl radicals. At concentrations typical for DNP, relaxation is mediated by excitation transfer and spin-diffusion to fast-relaxing centers identified as triads of trityl radicals that spontaneously form in the frozen samples. These centers relax by an Orbach-Aminov mechanism and determine the relaxation, saturation and electron spin dynamics during DNP.
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Affiliation(s)
- Hanjiao Chen
- Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, Alabama 35487-0336, USA.
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23
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Abbas K, Boutier-Pischon A, Auger F, Françon D, Almario A, Frapart YM. In vivo triarylmethyl radical stabilization through encapsulation in Pluronic F-127 hydrogel. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:147-156. [PMID: 27479038 DOI: 10.1016/j.jmr.2016.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 07/20/2016] [Accepted: 07/21/2016] [Indexed: 06/06/2023]
Abstract
In vivo electron paramagnetic resonance (EPR) imaging and spectroscopy are non-invasive technologies used to specifically detect and quantify paramagnetic species. However, the relative instability of spin probes such as triarylmethyl radicals limits their application to conduct oxygen quantification and mapping. In this study we encapsulated tetrathiatriarylmethyl radical (TAM; known as "Finland" probe) in Pluronic F-127 hydrogel (PF-127) in order to limit its degradation and evaluate its in vitro and in vivo EPR properties as a function of oxygen. Our results show that the EPR signal of encapsulated TAM in PF-127 hydrogel is similar to the one in solution. Although it is less sensitive to oxygen, it is suitable for oximetry. We also demonstrated that the incorporation of TAM in PF-127 hydrogel leads to an improved in vivo EPR stability of the radical under anesthesia. This new formulation enables high quality EPR imaging and oximetry and paves the way for the application of TAM radical-based probes in various biomedical fields.
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Affiliation(s)
- Kahina Abbas
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), FR3657 CICB, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France
| | - Audrey Boutier-Pischon
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), FR3657 CICB, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France
| | - Florian Auger
- Integrated Drug Discovery, Sanofi R&D, 1, Avenue Pierre-Brossolette, 91385 Chilly-Mazarin, France
| | - Dominique Françon
- Translational Science Unit, Sanofi R&D, 1, Avenue Pierre-Brossolette, 91385 Chilly-Mazarin, France
| | - Antonio Almario
- Integrated Drug Discovery, Sanofi R&D, 1, Avenue Pierre-Brossolette, 91385 Chilly-Mazarin, France
| | - Yves-Michel Frapart
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), FR3657 CICB, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France.
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24
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Kuzhelev AA, Shevelev GY, Krumkacheva OA, Tormyshev VM, Pyshnyi DV, Fedin MV, Bagryanskaya EG. Saccharides as Prospective Immobilizers of Nucleic Acids for Room-Temperature Structural EPR Studies. J Phys Chem Lett 2016; 7:2544-8. [PMID: 27320083 PMCID: PMC5453311 DOI: 10.1021/acs.jpclett.6b01024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for structural studies of biomolecules and their complexes. This method, whose applicability has been recently extended to room temperatures, requires immobilization of the studied biosystem to prevent averaging of dipolar couplings; at the same time, the modification of native conformations by immobilization must be avoided. In this work, we provide first demonstration of room-temperature EPR distance measurements in nucleic acids using saccharides trehalose, sucrose, and glucose as immobilizing media. We propose an approach that keeps structural conformation and unity of immobilized double-stranded DNA. Remarkably, room-temperature electron spin dephasing time of triarylmethyl-labeled DNA in trehalose is noticeably longer compared to previously used immobilizers, thus providing a broader range of available distances. Therefore, saccharides, and especially trehalose, can be efficiently used as immobilizers of nucleic acids, mimicking native conditions and allowing wide range of structural EPR studies at room temperatures.
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Affiliation(s)
- Andrey A. Kuzhelev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Georgiy Yu. Shevelev
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Olesya A. Krumkacheva
- International Tomography Center SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Victor M. Tormyshev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Dmitrii V. Pyshnyi
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Matvey V. Fedin
- International Tomography Center SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Elena G. Bagryanskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
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25
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Klein JH, Schmidt D, Steiner UE, Lambert C. Complete Monitoring of Coherent and Incoherent Spin Flip Domains in the Recombination of Charge-Separated States of Donor-Iridium Complex-Acceptor Triads. J Am Chem Soc 2015; 137:11011-21. [DOI: 10.1021/jacs.5b04868] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Johannes H. Klein
- Wilhelm
Conrad Röntgen Research Center for Complex Material Systems,
Würzburg, Center for Nanosystems Chemistry, Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - David Schmidt
- Wilhelm
Conrad Röntgen Research Center for Complex Material Systems,
Würzburg, Center for Nanosystems Chemistry, Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | | | - Christoph Lambert
- Wilhelm
Conrad Röntgen Research Center for Complex Material Systems,
Würzburg, Center for Nanosystems Chemistry, Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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26
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Frank J, Elewa M, Said MM, El Shihawy HA, El-Sadek M, Müller D, Meister A, Hause G, Drescher S, Metz H, Imming P, Mäder K. Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors. J Org Chem 2015; 80:6754-66. [PMID: 26020133 DOI: 10.1021/acs.joc.5b00918] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tissue oxygenation plays an important role in the pathophysiology of various diseases and is often a marker of prognosis and therapeutic response. EPR (ESR) is a suitable noninvasive oximetry technique. However, to reliably deploy soluble EPR probes as oxygen sensors in complex biological systems, there is still a need to investigate and improve their specificity, sensitivity, and stability. We reproducibly synthesized various derivatives of tetrathiatriarylmethyl and tetrachlorotriarylmethyl (trityl) radicals. Hydrophilic radicals were investigated in aqueous solution mimicking physiological conditions by, e.g., variation of viscosity and ionic strength. Their specificity was satisfactory, but the oxygen sensitivity was low. To enhance the capability of trityl radicals as oxygen sensors, encapsulation into oily core nanocapsules was performed. Thus, different lipophilic triesters were prepared and characterized in oily solution employing oils typically used in drug formulations, i.e., middle-chain triglycerides and isopropyl myristate. Our screening identified the deuterated ethyl ester of D-TAM (radical 13) to be suitable. It had an extremely narrow single EPR line under anoxic conditions and excellent oxygen sensitivity. After encapsulation, it retained its oxygen responsiveness and was protected against reduction by ascorbic acid. These biocompatible and highly sensitive nanosensors offer great potential for future EPR oximetry applications in preclinical research.
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Affiliation(s)
- Juliane Frank
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Marwa Elewa
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany.,‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | - Mohamed M Said
- ‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | - Hosam A El Shihawy
- ‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | | | - Diana Müller
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Annette Meister
- ⊥Center for Structure and Dynamics of Proteins (MZP), Biocenter Martin-Luther-Universität (MLU) Halle-Wittenberg, Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Gerd Hause
- #Biocenter Martin-Luther-Universität (MLU) Halle-Wittenberg, Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Simon Drescher
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Hendrik Metz
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Peter Imming
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Karsten Mäder
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
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27
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Kuzhelev AA, Trukhin DV, Krumkacheva OA, Strizhakov RK, Rogozhnikova OY, Troitskaya TI, Fedin MV, Tormyshev VM, Bagryanskaya EG. Room-Temperature Electron Spin Relaxation of Triarylmethyl Radicals at the X- and Q-Bands. J Phys Chem B 2015; 119:13630-13640. [PMID: 26001103 DOI: 10.1021/acs.jpcb.5b03027] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Triarylmethyl radicals (trityls, TAMs) represent a relatively new class of spin labels. The long relaxation of trityls at room temperature in liquid solutions makes them a promising alternative for traditional nitroxides. In this work we have synthesized a series of TAMs including perdeuterated Finland trityl (D36 form), mono-, di-, and triester derivatives of Finland-D36 trityl, the deuterated form of OX63, the dodeca-n-butyl homologue of Finland trityl, and triamide derivatives of Finland trityl with primary and secondary amines attached. We have studied room-temperature relaxation properties of these TAMs in liquids using pulsed electron paramagnetic resonance (EPR) at two microwave frequency bands. We have found the clear dependence of phase memory time (Tm ∼ T2) on the magnetic field: room-temperature Tm values are ∼1.5-2.5 times smaller at the Q-band (34 GHz, 1.2 T) than at the X-band (9 GHz, 0.3 T). This trend is ascribed to the contribution from g-anisotropy that is negligible at lower magnetic fields but comes into play at the Q-band. In agreement with this, the difference between T1 and Tm becomes more pronounced at the Q-band than at the X-band due to increased contributions from incomplete motional averaging of g-anisotropy. Linear dependence of (1/Tm - 1/T1) on viscosity implies that g-anisotropy is modulated by rotational motion of the trityl radical. On the basis of the analysis of previous data and results of the present work, we conclude that, in the general situation where the spin label is at least partly mobile, the X-band is most suitable for application of trityls for room-temperature pulsed EPR distance measurements.
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Affiliation(s)
- Andrey A Kuzhelev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Dmitry V Trukhin
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Olesya A Krumkacheva
- International Tomography Center SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Rodion K Strizhakov
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia
| | - Olga Yu Rogozhnikova
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Tatiana I Troitskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Matvey V Fedin
- International Tomography Center SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Victor M Tormyshev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
| | - Elena G Bagryanskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
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28
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Elajaili HB, Biller JR, Tseitlin M, Dhimitruka I, Khramtsov VV, Eaton SS, Eaton GR. Electron spin relaxation times and rapid scan EPR imaging of pH-sensitive amino-substituted trityl radicals. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:280-4. [PMID: 25504559 PMCID: PMC4374029 DOI: 10.1002/mrc.4193] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/16/2014] [Accepted: 11/03/2014] [Indexed: 05/26/2023]
Abstract
Carboxy-substituted trityl (triarylmethyl) radicals are valuable in vivo probes because of their stability, narrow lines, and sensitivity of their spectroscopic properties to oxygen. Amino-substituted trityl radicals have the potential to monitor pH in vivo, and the suitability for this application depends on spectral properties. Electron spin relaxation times T1 and T2 were measured at X-band for the protonated and deprotonated forms of two amino-substituted triarylmethyl radicals. Comparison with relaxation times for carboxy-substituted triarylmethyl radicals shows that T1 exhibits little dependence on protonation or the nature of the substituent, which makes it useful for measuring O2 concentration, independent of pH. Insensitivity of T1 to changes in substituents is consistent with the assignment of the dominant contribution to spin lattice relaxation as a local mode that involves primarily atoms in the carbon and sulfur core. Values of T2 vary substantially with pH and the nature of the aryl group substituent, reflecting a range of dynamic processes. The narrow spectral widths for the amino-substituted triarylmethyl radicals facilitate spectral-spatial rapid scan electron paramagnetic resonance imaging, which was demonstrated with a phantom. The dependence of hyperfine splittings patterns on pH is revealed in spectral slices through the image.
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Affiliation(s)
- Hanan B Elajaili
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
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29
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Boutier-Pischon A, Auger F, Noël JM, Almario A, Frapart YM. EPR and electrochemical quantification of oxygen using newly synthesized para-silylated triarylmethyl radicals. Free Radic Res 2014; 49:236-43. [PMID: 25488370 DOI: 10.3109/10715762.2014.995183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Novel silylated triarylmethyl (TAM) radicals based on TAM core CT-03 and their electron paramagnetic resonance (EPR) spectra are evaluated as a function of oxygen concentration. Combination of peak-to-peak linewidth of the EPR signal and electrochemical determination allows designing a method for oxygen quantification in phosphate buffer, dimethylsulfoxide, and dichloromethane, which can be extended to other solvents.
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Affiliation(s)
- A Boutier-Pischon
- LCBPT, UMR 8601 CNRS-Paris Descartes University , Sorbonne Paris Cité, Paris , France
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30
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Shin BK. A simple quasi-analytical method for the deconvolution of Voigtian profiles. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 249:1-8. [PMID: 25462940 DOI: 10.1016/j.jmr.2014.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 09/21/2014] [Accepted: 09/23/2014] [Indexed: 06/04/2023]
Abstract
In electron spin resonance spectroscopy, spectral lineshapes are often assumed to be Voigtian. A number of researchers have suggested ways to approximate the Voigtian profile. Herein, we have devised a new quasi-analytical method to deconvolve it. In particular, we have derived an equation that relates the Lorentzian-to-Gaussian linewidth ratio directly to the product of the linewidth and the maximum value of a normalized Voigtian profile. Our calculations show that the Lorentzian and Gaussian linewidths obtained by the quasi-analytical deconvolution of computer-generated Voigtian absorption spectra are accurate within an error range of 1% in the absence of noise. Also, simulations with noise-added spectra reveal that, in the presence of white noise, our method is valid to a certain extent that depends on several factors such as the number of data points and the spectral sweep width. The new deconvolution method is valuable in that it estimates the Lorentzian and Gaussian linewidth in a rapid manner. The method may be also useful in other fields of science, such as optical spectroscopy, especially if some a priori knowledge about the lineshape is given.
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Affiliation(s)
- Byong-Kyu Shin
- Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, United States; College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea.
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31
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Takahashi W, Bobko AA, Dhimitruka I, Hirata H, Zweier JL, Samouilov A, Khramtsov VV. Proton-Electron Double-Resonance Imaging of pH using phosphonated trityl probe. APPLIED MAGNETIC RESONANCE 2014; 45:817-826. [PMID: 25530673 PMCID: PMC4268155 DOI: 10.1007/s00723-014-0570-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Variable Radio Frequency Proton-Electron Double-Resonance Imaging (VRF PEDRI) enables extracting a functional map from a limited number of images acquired at pre-selected EPR frequencies using specifically designed paramagnetic probes with high quality spatial resolution and short acquisition times. In this work we explored potential of VRF PEDRI for pH mapping of aqueous samples using recently synthesized pH-sensitive phosphonated trityl radical, pTR. The ratio of Overhauser enhancements measured at each pixel at two different excitation frequencies corresponding to the resonances of protonated and deprotonated forms of pTR probe allows for a pH map extraction. Long relaxation times of pTR allow for pH mapping at EPR irradiation power as low as 1.25 W during 130 s acquisition time with spatial resolution of about 1 mm. This is particularly important for in vivo applications enabling one to avoid sample overheating by reducing RF power deposition.
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Affiliation(s)
- Wataru Takahashi
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA ; Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Andrey A Bobko
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Ilirian Dhimitruka
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Jay L Zweier
- Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Alexandre Samouilov
- Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Valery V Khramtsov
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
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32
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Bobko AA, Dhimitruka I, Zweier JL, Khramtsov VV. Fourier transform EPR spectroscopy of trityl radicals for multifunctional assessment of chemical microenvironment. Angew Chem Int Ed Engl 2014; 53:2735-8. [PMID: 24488710 PMCID: PMC3985337 DOI: 10.1002/anie.201310841] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Indexed: 12/29/2022]
Abstract
Pulse techniques in electron paramagnetic resonance (EPR) allow for a reduction in measurement times and increase in sensitivity but require the synthesis of paramagnetic probes with long relaxation times. Here it is shown that the recently synthesized phosphonated trityl radical possesses long relaxation times that are sensitive to probe the microenvironment, such as oxygenation and acidity of an aqueous solution. In principle, application of Fourier transform EPR (FT-EPR) spectroscopy makes it possible to acquire the entire EPR spectrum of the trityl probe and assess these microenvironmental parameters within a few microseconds. The performed analysis of the FT-EPR spectra takes into consideration oxygen-, proton-, buffer-, and concentration-induced contributions to the spectral shape, therefore enabling quantitative and discriminative assessment of pH, pO2, and concentrations of the probe and inorganic phosphate.
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Affiliation(s)
- Andrey A. Bobko
- Dorothy M. Davis Heart & Lung Research Institute and Division of Pulmonary, Allergy Critical Care & Sleep Medicine, Department of Internal Medicine, The Ohio State University, 201 HLRI, 473 W 12th Ave, Columbus, OH 43210 (USA)
| | - Ilirian Dhimitruka
- Dorothy M. Davis Heart & Lung Research Institute and Division of Pulmonary, Allergy Critical Care & Sleep Medicine, Department of Internal Medicine, The Ohio State University, 201 HLRI, 473 W 12th Ave, Columbus, OH 43210 (USA)
| | - Jay L. Zweier
- Dorothy M. Davis Heart & Lung Research Institute and Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Ohio (USA)
| | - Valery V. Khramtsov
- Dorothy M. Davis Heart & Lung Research Institute and Division of Pulmonary, Allergy Critical Care & Sleep Medicine, Department of Internal Medicine, The Ohio State University, 201 HLRI, 473 W 12th Ave, Columbus, OH 43210 (USA)
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33
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Bobko AA, Dhimitruka I, Zweier JL, Khramtsov VV. Fourier Transform EPR Spectroscopy of Trityl Radicals for Multifunctional Assessment of Chemical Microenvironment. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201310841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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McKenzie I. Spin relaxation of a short-lived radical in zero magnetic field. Phys Chem Chem Phys 2011; 13:1168-73. [DOI: 10.1039/c0cp01216e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Iain McKenzie
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton Didcot, UK.
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35
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Sato H, Kathirvelu V, Fielding A, Blinco JP, Micallef AS, Bottle SE, Eaton SS, Eaton GR. Impact of molecular size on electron spin relaxation rates of nitroxyl radicals in glassy solvents between 100 and 300 K. Mol Phys 2010. [DOI: 10.1080/00268970701724966] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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36
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Halevy R, Tormyshev V, Blank A. Microimaging of oxygen concentration near live photosynthetic cells by electron spin resonance. Biophys J 2010; 99:971-8. [PMID: 20682276 DOI: 10.1016/j.bpj.2010.05.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 04/13/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022] Open
Abstract
We present what is, to our knowledge, a new methodology for high-resolution three-dimensional imaging of oxygen concentration near live cells. The cells are placed in the buffer solution of a stable paramagnetic probe, and electron spin-resonance microimaging is employed to map out the probe's spin-spin relaxation time (T(2)). This information is directly linked to the concentration of the oxygen molecule. The method is demonstrated with a test sample and with a small amount of live photosynthetic cells (cyanobacteria), under conditions of darkness and light. Spatial resolution of approximately 30 x 30 x 100 microm is demonstrated, with approximately microM oxygen concentration sensitivity and sub-fmol absolute oxygen sensitivity per voxel. The use of electron spin-resonance microimaging for oxygen mapping near cells complements the currently available techniques based on microelectrodes or fluorescence/phosphorescence. Furthermore, with the proper paramagnetic probe, it will also be readily applicable for intracellular oxygen microimaging, a capability which other methods find very difficult to achieve.
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Affiliation(s)
- Revital Halevy
- Schulich Faculty of Chemistry Technion, Israel Institute of Technology, Haifa, Israel
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37
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Kathirvelu V, Sato H, Eaton SS, Eaton GR. Electron spin relaxation rates for semiquinones between 25 and 295K in glass-forming solvents. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 198:111-120. [PMID: 19223213 PMCID: PMC2757793 DOI: 10.1016/j.jmr.2009.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2008] [Revised: 01/13/2009] [Accepted: 01/22/2009] [Indexed: 05/27/2023]
Abstract
Electron spin lattice relaxation rates for five semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,5-di-t-amyl-1,4-benzosemiquinone, 2,5-di-phenyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, tetrahydroxy-1,4-benzosemiquione) were studied by long-pulse saturation recovery EPR in 1:4 glycerol:ethanol, 1:1 glycerol:ethanol, and triethanolamine between 25 and 295K. Although the dominant process changes with temperature, relaxation rates vary smoothly with temperature, even near the glass transition temperatures, and could be modeled as the sum of contributions that have the temperature dependence that is predicted for the direct, Raman, local mode and tumbling-dependent processes. At 85K, which is in a temperature range where the Raman process dominates, relaxation rates along the g(xx) (g approximately 2.006) and g(yy) (g approximately 2.005) axes are about 2.7-1.5 times faster than along the g(zz) axis (g=2.0023). In highly viscous triethanolamine, contributions from tumbling-dependent processes are negligible. At temperatures above 100K relaxation rates in triethanolamine are unchanged between X-band (9.5GHz) and Q-band (34GHz), so the process that dominates in this temperature interval was assigned as a local mode rather than a thermally activated process. Because the largest proton hyperfine couplings are only 2.2G, spin rotation makes a larger contribution than tumbling-dependent modulation of hyperfine anisotropy. Since g anisotropy is small, tumbling-dependent modulation of g anisotropy makes a smaller contribution than spin rotation at X-band. Although there was negligible impact of methyl rotation on T(1), rotation of t-butyl or t-amyl methyl groups enhances spin echo dephasing between 85 and 150K.
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Affiliation(s)
| | | | - Sandra S. Eaton
- Corresponding author: Professor Sandra S. Eaton, Department of Chemistry and Biochemistry, University of Denver Denver, CO 80208, 303-871-3102, Fax: 303-871-2254,
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Kathirvelu V, Eaton GR, Eaton SS. Impact of Chlorine Substitution on Spin Lattice Relaxation of Triarylmethyl and 1,4-Benzosemiquinone Radicals in Glass-forming Solvents between 25 and 295 K. APPLIED MAGNETIC RESONANCE 2009; 37:649. [PMID: 20126423 PMCID: PMC2814433 DOI: 10.1007/s00723-009-0086-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Spin-lattice relaxation rates measured by long-pulse saturation recovery in glassy solvents for chlorinated aromatic radicals: perchlorotriphenylmethyl radical, 2,5-dichloro-3,6-dihydroxy-1,4-benzosemiquinone, and tetrachloro-1,4-benzosemiquinone, were compared with relaxation rates for non-chlorinated analogs. The impact of the quadrupolar chlorines is small, and less than the effects of changing the rigidity of the glass. The temperature dependence of relaxation rates below the glass transition temperature could be modeled as the sum of contributions from the direct, Raman, and local mode processes.
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Affiliation(s)
- Velavan Kathirvelu
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
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Blank A, Talmon Y, Shklyar M, Shtirberg L, Harneit W. Direct measurement of diffusion in liquid phase by electron spin resonance. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.09.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Subramanian S, Krishna MC. DANCING WITH THE ELECTRONS: TIME-DOMAIN AND CW IN VIVO EPR IMAGING. MAGNETIC RESONANCE INSIGHTS 2008; 2:43-74. [PMID: 22025900 DOI: 10.4137/mri.s1131] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The progress in the development of imaging the distribution of unpaired electrons in living systems and the functional and the potential diagnostic dimensions of such an imaging process, using Electron Paramagnetic Resonance Imaging (EPRI), is traced from its origins with emphasis on our own work. The importance of EPR imaging stems from the fact that many paramagnetic probes show oxygen dependent spectral broadening. Assessment of in vivo oxygen concentration is an important factor in radiation oncology in treatment-planning and monitoring treatment-outcome. The emergence of narrow-line trairylmethyl based, bio-compatible spin probes has enabled the development of radiofrequency time-domain EPRI. Spectral information in time-domain EPRI can be achieved by generating a time sequence of T(2)* or T(2) weighted images. Progress in CW imaging has led to the use of rotating gradients, more recently rapid scan with direct detection, and a combination of all the three. Very low field MRI employing Dynamic Nuclear polarization (Overhauser effect) is also employed for monitoring tumor hypoxia, and re-oxygenation in vivo. We have also been working on the co-registration of MRI and time domain EPRI on mouse tumor models at 300 MHz using a specially designed resonator assembly. The mapping of the unpaired electron distribution and unraveling the spectral characteristics by using magnetic resonance in presence of stationary and rotating gradients in indeed 'dancing with the (unpaired) electrons', metaphorically speaking.
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Affiliation(s)
- Sankaran Subramanian
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Ahn KH, Subramanian VS, Halpern HJ. Scaling of EPR spectral-spatial images with size of sample: images of a sample greater than 5 cm in linear dimension. Med Phys 2008; 34:4854-9. [PMID: 18196811 DOI: 10.1118/1.2804745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The authors have obtained spectral-spatial EPR images of a phantom significantly larger than those previously obtained. Images of a homogeneous phantom 4.2 cm in diameter and 6.5 cm in length with B1 equivalent to that used for smaller samples give a similar linewidth resolution both with linewidth population distributions of width 0.1 microT. Spatial resolution appeared to have modest degradation. Images of the large homogeneous phantom provide maps of the magnetic field of a partially shimmed magnet.
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Affiliation(s)
- Kang-Hyun Ahn
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois 60637, USA
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Sato H, Bottle SE, Blinco JP, Micallef AS, Eaton GR, Eaton SS. Electron spin-lattice relaxation of nitroxyl radicals in temperature ranges that span glassy solutions to low-viscosity liquids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 191:66-77. [PMID: 18166493 PMCID: PMC2671210 DOI: 10.1016/j.jmr.2007.12.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 12/07/2007] [Accepted: 12/07/2007] [Indexed: 05/12/2023]
Abstract
Electron spin-lattice relaxation rates, 1/T1, at X-band of nitroxyl radicals (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-oxyl and 3-carbamoyl-2,2,5,5-tetramethylpyrrolin-1-oxyl) in glass-forming solvents (decalin, glycerol, 3-methylpentane, o-terphenyl, 1-propanol, sorbitol, sucrose octaacetate, and 1:1 water:glycerol) at temperatures between 100 and 300K were measured by long-pulse saturation recovery to investigate the relaxation processes in slow-to-fast tumbling regimes. A subset of samples was also studied at lower temperatures or at Q-band. Tumbling correlation times were calculated from continuous wave lineshapes. Temperature dependence and isotope substitution (2H and 15N) were used to distinguish the contributions of various processes. Below about 100K relaxation is dominated by the Raman process. At higher temperatures, but below the glass transition temperature, a local mode process makes significant contributions. Above the glass transition temperature, increased rates of molecular tumbling modulate nuclear hyperfine and g anisotropy. The contribution from spin rotation is very small. Relaxation rates at X-band and Q-band are similar. The dependence of 1/T1 on tumbling correlation times fits better with the Cole-Davidson spectral density function than with the Bloembergen-Purcell-Pound model.
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Affiliation(s)
- Hideo Sato
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
| | - Steven E. Bottle
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434 Q4001, Australia
| | - James P. Blinco
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434 Q4001, Australia
| | - Aaron S. Micallef
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434 Q4001, Australia
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208
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Liu Y, Villamena FA, Sun J, Xu Y, Dhimitruka I, Zweier JL. Synthesis and Characterization of Ester-Derivatized Tetrathiatriarylmethyl Radicals as Intracellular Oxygen Probes. J Org Chem 2008; 73:1490-7. [DOI: 10.1021/jo7022747] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yangping Liu
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
| | - Frederick A. Villamena
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
| | - Jian Sun
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
| | - Yingkai Xu
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
| | - Ilirian Dhimitruka
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
| | - Jay L. Zweier
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, and Department of Pharmacology, College of Medicine, The Ohio State University, Columbus, Ohio 43210
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Hama Y, Matsumoto KI, Murugesan R, Subramanian S, Devasahayam N, Koscielniak JW, Hyodo F, Cook JA, Mitchell JB, Krishna MC. Continuous wave EPR oximetric imaging at 300 MHz using radiofrequency power saturation effects. Antioxid Redox Signal 2007; 9:1709-16. [PMID: 17696765 DOI: 10.1089/ars.2007.1720] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A novel continuous wave (CW), radiofrequency (RF), electron paramagnetic resonance (EPR) oximetric imaging technique is proposed, based on the influence of oxygen concentration on the RF power saturation of the EPR resonance. A linear relationship is demonstrated between the partial oxygen pressure (pO(2)) and the normalized signal intensity (I(N)), defined as, I(N) = (I(HP) - I(LP))/I(LP), where I(LP) and I(HP) refer to signal intensities at low (P(L)) and high (P(H)) RF power levels, respectively. A formula for the determination of pO(2), derived on the basis of the experimental results, reliably estimated various oxygen concentrations in a five-tube phantom. This new technique was time-efficient and also avoided the missing angle problem associated with conventional spectral-spatial CW EPR oximetric imaging. In vivo power saturation oximetric imaging in a tumor bearing mouse clearly depicted the hypoxic foci within the tumor.
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Affiliation(s)
- Yukihiro Hama
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1002, USA
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Devasahayam N, Subramanian S, Murugesan R, Hyodo F, Matsumoto KI, Mitchell JB, Krishna MC. Strategies for improved temporal and spectral resolution in in vivo oximetric imaging using time-domain EPR. Magn Reson Med 2007; 57:776-83. [PMID: 17390350 DOI: 10.1002/mrm.21194] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A radiofrequency (RF) time-domain electron paramagnetic resonance (EPR) instrument operating at 300, 600, and 750 MHz was used to image tumor hypoxia with high spatial and temporal resolution. A high-speed signal-averaging Peripheral Component Interconnect (PCI) board with flexibility in the input signal level and the number of digitized samples per free induction decay (FID) was incorporated into the receive arm of the spectrometer. This enabled effective and fast averaging of FIDs. Modification of the phase-encoding protocol, and replacement of the General Purpose Interface Bus (GPIB)-based handshake with a PCI-based D/A board for direct control of the gradient amplifier decreased the gradient settling and communication overhead times by nearly two orders of magnitude. Cyclically-ordered phase sequence (CYCLOPS) phase cycling was implemented to correct for pulse imperfections and cancel out unwanted constant signals. These upgrades considerably enhanced the performance of the imager in terms of image collection time, sensitivity, and temporal resolution. We demonstrated this by collecting a large number of 2D images successively and rapidly. The results show that it is feasible to achieve accurate, 2D pO(2) maps of tumor hypoxia with 1-mm(2) resolution and minimal artifacts using a set of multigradient images within an acceptable measuring time of about 3 s, and 3D maps can be obtained in less than 1 min.
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Affiliation(s)
- Nallathamby Devasahayam
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
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Rawls MT, Kollmannsberger G, Elliott CM, Steiner UE. Spin chemical control of photoinduced electron-transfer processes in ruthenium(II)-trisbipyridine-based supramolecular triads: 2. The effect of oxygen, sulfur, and selenium as heteroatom in the azine donor. J Phys Chem A 2007; 111:3485-96. [PMID: 17432838 DOI: 10.1021/jp070221s] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nanosecond time-resolved absorption studies in a magnetic field ranging from 0 to 2.0 T have been performed on a series of covalently linked donor(PXZ)-Ru(bipyridine)3-acceptor(diquat) complexes (D-C2+-A2+). In the PXZ moiety, the heteroatom (X = O (oxygen), T (sulfur), and S (selenium)) is systematically varied to study spin-orbit coupling effects. On the nanosecond time scale, the first detectable photoinduced electron-transfer product after exciting the chromophore C2+ is the charge-separated (CS) state, D+-C2+-A+, where an electron of the PXZ moiety, D, has been transferred to the diquat moiety, A2+. The magnetic-field-dependent kinetic behavior of charge recombination (monoexponential at 0 T progressing to biexponential for all three complexes with increasing field) can be quantitatively modeled by the radical pair relaxation mechanism assuming creation of the CS state with pure triplet spin correlation (3CS). Magnetic-field-independent contributions to the rate constant kr of T+/- --> (T0,S) relaxation are about 4.5 x 10(5) s-1 for DCA-POZ and -PTZ (due to a vibrational mechanism) and 3.5 x 10(6) s-1 for DCA-PSZ (due to spin rotational mechanism). Recombination to the singlet ground state is allowed only from the 1CS spin level; spin-forbidden recombination from 3CS seems negligible even for DCA-PSZ. The field dependence of kr (field-dependent recombination) can be decomposed into the contributions of various relaxation mechanisms. For all compounds, the electron spin dipolar coupling relaxation mechanism dominates the field dependence of tau(slow) at fields up to about 100 mT. Spin relaxation due to the g-tensor anisotropy relaxation mechanism accounts for the field dependence of tau(slow) for DCA-PSZ at high fields. For the underlying stochastic process, a very short correlation time of 2 ps has to be assumed, which is tentatively assigned to a flapping motion of the central, nonplanar ring in PSZ. Finally, it has been confirmed by paramagnetic quenching (here Heisenberg exchange) experiments of the magnetic-field effects with TEMPO that all magnetic-field dependencies observed with the present DCA-PSZ systems are indeed due to the magnetic-field dependence of spin relaxation.
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Affiliation(s)
- Matthew T Rawls
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
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48
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Mailer C, Sundramoorthy SV, Pelizzari CA, Halpern HJ. Spin echo spectroscopic electron paramagnetic resonance imaging. Magn Reson Med 2006; 55:904-12. [PMID: 16526015 DOI: 10.1002/mrm.20849] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The use of spin echoes to obtain spectroscopic EPR images (spectral-spatial images) at 250 MHz is described. The advantages of spin echoes-larger signals than the free induction decay, better phase characteristics for Fourier transformation, and decay shapes undistorted by instrumental dead time-are clearly shown. An advantage is gained from using a crossed loop resonator that isolates the 250-W pump power by greater than 50 dB from the observer arm preamplifiers. The echo decay rates can be used to determine the oxygen content in solutions containing 1 mM trityl concentrations. Two- and three-dimensional images of oxygen concentration are presented.
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Affiliation(s)
- Colin Mailer
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois 60637, USA.
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Blank A, Freed JH, Kumar NP, Wang CH. Electron spin resonance microscopy applied to the study of controlled drug release. J Control Release 2006; 111:174-84. [PMID: 16460828 DOI: 10.1016/j.jconrel.2005.11.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 10/31/2005] [Accepted: 11/03/2005] [Indexed: 10/25/2022]
Abstract
We describe our recent developments towards 3D micron-scale imaging capability, based on electron spin resonance (ESR), and its application to the study of controlled release. The method, termed ESR microscopy (ESRM), is an extension of the conventional "millimeter-scale" ESR imaging technique. It employs paramagnetic molecules (such as stable radicals or spin-labeled drugs) and may enable one to obtain accurate 3D spatially resolved information about the drug concentration, its self-diffusion tensor, rotational correlation time and the pH in the release matrix. Theoretical calculations, along with initial experimental results, suggest that a 3D resolution of approximately 1 microm is feasible with this method. Here we were able to image successfully a high spin concentration sample with a resolution of approximately 3 x 3 x 8 microm and subsequently study a single approximately 120 microm biodegradable microsphere, internalized with a dilute solution of trityl radical, with a resolution of approximately 12.7 x 13.2 x 26 microm. Analysis of the microsphere ESR imaging data revealed a likely increase in the viscosity inside the sphere and/or binding of the radical molecule to the sphere matrix. Future directions for progress are also discussed.
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Affiliation(s)
- Aharon Blank
- National Biomedical Center for Advanced ESR Technology, Department of Chemistry and Chemical Biology, B-52 Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA
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50
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Bowman MK, Mailer C, Halpern HJ. The solution conformation of triarylmethyl radicals. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 172:254-267. [PMID: 15649753 DOI: 10.1016/j.jmr.2004.10.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 10/21/2004] [Indexed: 05/24/2023]
Abstract
Hyperfine coupling tensors to 1H, 2H, and natural abundance 13C were measured using X-band pulsed electron nuclear double resonance (ENDOR) spectroscopy for two triarylmethyl (trityl) radicals used in electron paramagnetic resonance imaging and oximetry: methyl tris(8-carboxy-2,2,6,6-tetramethyl-benzo[1,2d:4,5-d']bis(1,3)dithiol-4-yl) and methyl tris(8-carboxy-2,2,6,6-tetramethyl(-d3)-benzo[1,2d:4,5-d']bis(1,3)dithiol-4-yl). Quantum chemical calculations using density functional theory predict a structure that reproduces the experimentally determined hyperfine tensors. The radicals are propeller-shaped with the three aryl rings nearly mutually orthogonal. The central carbon atom carrying most of the unpaired electron spin density is surrounded by the sulfur atoms in the radical and is completely shielded from solvent. This structure explains features of the electron spin relaxation of these radicals and suggests ways in which the radicals can be chemically modified to improve their characteristics for imaging and oximetry.
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Affiliation(s)
- M K Bowman
- Structural Biology and Microimaging, Pacific Northwest National Laboratory, Richland, WA 99352-0999, USA.
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