Startseite Naturwissenschaften 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
Artikel
Lizenziert
Nicht lizenziert Erfordert eine Authentifizierung

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

  • Yilin Shi , Richard W. Quine , George A. Rinard , Laura Buchanan , Sandra S. Eaton , Gareth R. Eaton EMAIL logo , Boris Epel , Simone Wanless Seagle und Howard J. Halpern
Veröffentlicht/Copyright: 18. November 2016
Zeitschrift für Physikalische Chemie
Aus der Zeitschrift Zeitschrift für Physikalische Chemie Band 231 Heft 4

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.

Keywords: cross loop resonator; electron spin relaxation; in vivo imaging; tumbling

Dedicated to: Kev Salikhov on the occasion of his 80th birthday.

Acknowledgments

This research was funded in part by NIH P41 EB002034 (HJH, PI), R01 CA098575 (HJH, PI) and R01CA177744 (GRE, PI). Loans of equipment from Bruker BioSpin contributed to the success.

References

1. I. Dhimitruka, A. A. Bobko, T. D. Eubank, D. A. Komarov, V. V. Khramtsov, J. Am. Chem. Soc. 135 (2013) 5904.10.1021/ja401572rSuche in Google Scholar PubMed PubMed Central

2. B. B. Williams, H. J. Halpern, Biol. Magn. Reson. 23 (2005) 283.10.1007/0-387-26741-7_11Suche in Google Scholar

3. E. Epel, M. K. Bowman, C. Mailer, H. Halpern, Magn. Reson. Med. 27 (2014) 362.10.1002/mrm.24926Suche in Google Scholar PubMed PubMed Central

4. B. Epel, H. Halpern, Methods Enzymol. 564 (2015) 501.10.1016/bs.mie.2015.08.017Suche in Google Scholar PubMed PubMed Central

5. L. J. Berliner, In Vivo EPR (ESR): Theory and Application, Kluwer Academic, New York (2003).10.1007/978-1-4615-0061-2Suche in Google Scholar

6. A. A. Bobko, I. Dhimitruka, J. L. Zweier, V. V. Khramtsov, J. Am. Chem. Soc. 129 (2007) 7240.10.1021/ja071515uSuche in Google Scholar PubMed

7. L. Yong, J. Harbridge, R. W. Quine, G. A. Rinard, S. S. Eaton, G. R. Eaton, C. Mailer, E. Barth, H. J. Halpern, J. Magn. Reson. 152 (2001) 156.10.1006/jmre.2001.2379Suche in Google Scholar PubMed

8. H. J. Halpern, D. P. Spencer, J. van Polen, M. K. Bowman, A. C. Nelson, E. M. Dowey, B. A. Teicher, Rev. Sci. Instrum. 60 (1989) 1040.10.1063/1.1140314Suche in Google Scholar

9. H. J. Halpern, M. K. Bowman, in EPR Imaging and In Vivo EPR, G. R. Eaton et al., Eds., CRC Press, Boca Raton (1991), ch. 6.Suche in Google Scholar

10. A. Kuzhelev, D. Trukhin, O. Krumkacheva, R. Strizhakov, O. Rogozhnikova, T. Troitskaya, M. Fedin, V. Tormyshev, E. Bagryanskaya, J. Phys. Chem. B 119 (2015) 13630.10.1021/acs.jpcb.5b03027Suche in Google Scholar PubMed PubMed Central

11. R. W. Quine, G. A. Rinard, Y. Shi, L. A. Buchanan, J. R. Biller, S. S. Eaton, G. R. Eaton, Magn. Reson. B, Magn. Reson. Engineering accepted for publication (2016).Suche in Google Scholar

12. R. W. Quine, G. A. Rinard, B. T. Ghim, S. S. Eaton, G. R. Eaton, Rev. Sci. Instrum. 67 (1996) 2514.10.1063/1.1147206Suche in Google Scholar

13. R. Owenius, G. R. Eaton, S. S. Eaton, J. Magn. Reson. 172 (2005) 168.10.1016/j.jmr.2004.10.007Suche in Google Scholar

14. M. K. Bowman, C. Mailer, H. J. Halpern, J. Magn. Reson. 172 (2005) 254.10.1016/j.jmr.2004.10.010Suche in Google Scholar

15. S. N. Trukhan, V. F. Yudanov, O. Rogozhnikova, D. Trukhin, M. K. Bowman, M. D. Krzyaniak, H. Chen, O. N. Martyanov, J. Magn. Reson. 233 (2013) 29.10.1016/j.jmr.2013.04.017Suche in Google Scholar

16. G. A. Rinard, R. W. Quine, S. S. Eaton, G. R. Eaton, Biol. Magn. Reson. 21 (2004) 115.10.1007/978-1-4419-8951-2_3Suche in Google Scholar

17. G. A. Rinard, S. S. Eaton, G. R. Eaton, C. P. Poole, Jr., H. A. Farach, Handbook of Electron Spin Resonance 2 (1999) 1.10.1007/978-1-4612-1486-1_1Suche in Google Scholar

18. D. H. Gadani, V. A. Rana, S. P. Bhatnagar, A. N. Prajapati, A.D. Vyas, Indian J. Pure Appl. Phys. 50 (2012) 405.Suche in Google Scholar

19. P. A. Bottomley, E. R. Andrew, Phys. Biol. Med. 23 (1978) 630.10.1088/0031-9155/23/4/006Suche in Google Scholar

20. D. I. Hoult, P. C. Lauterbur, J. Magn. Reson. 34 (1979) 425.10.1016/0022-2364(79)90019-2Suche in Google Scholar

21. T. W. Redpath, J. M. S. Hutchison, Magn. Reson. Imag. 2 (1984) 295.10.1016/0730-725X(84)90195-4Suche in Google Scholar

22. P. Roschmann, Med. Phys. 14 (1987) 922.10.1118/1.595995Suche in Google Scholar PubMed

23. I. Marin-Montesinos, J. C. Paniagua, M. Vilaseca, A. Urtizberea, F. Luis, M. Feliz, F. Lin, S. Van Doorslaer, M. Pons, Phys. Chem. Chem. Phys. 17 (2015) 5785.10.1039/C4CP05225KSuche in Google Scholar PubMed

24. S. Chandresekhar, Rev. Modern Phys. 15 (1943) 1.10.1103/RevModPhys.15.1Suche in Google Scholar

Supplemental Material:

The online version of this article (DOI: 10.1515/zpch-2016-0813) offers supplementary material, available to authorized users.

Received: 2016-6-11
Accepted: 2016-10-20
Published Online: 2016-11-18
Published in Print: 2017-4-1

©2017 Walter de Gruyter GmbH, Berlin/Boston

Artikel in diesem Heft

  1. Frontmatter
  2. Preface
  3. Basic and Combination Cross-Features in X- and Q-band HYSCORE of the 15N Labeled Bacteriochlorophyll a Cation Radical
  4. An EPR Study of Small Magnetic Nanoparticles
  5. Magnetic Resonance Study of the Spin-1/2 Quantum Magnet BaAg2Cu[VO4]2
  6. Triarylmethyl Radicals: An EPR Study of 13C Hyperfine Coupling Constants
  7. Natural Abundance Nitrogen-15 NMR in Thermotropic Liquid Crystals With Cyano-Group
  8. Surface Hydroxyl OH Defects of η-Al2O3 and χ-Al2O3 by Solid State NMR, XRD, and DFT Calculations
  9. THz ESR study of Spinel Compound GeCo2O4
  10. Self-Association of Glycyrrhizic Acid. NMR Study
  11. A Site-Specific Study of the Magnetic Field-Dependent Proton Spin Relaxation of an Iridium N-Heterocyclic Carbene Complex
  12. Multifrequency Multiresonance EPR Investigation of Halogen-bonded Complexes Involving Neutral Nitroxide Radicals
  13. Electron Paramagnetic Resonance and DFT Analysis of the Effects of Bulky Perfluoroalkyl Substituents on a Vanadyl Perfluoro Phthalocyanine
  14. Coordination of the Mn4+-Center in Layered Li[Co0.98Mn0.02]O2 Cathode Materials for Lithium-Ion Batteries
  15. 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
https://doi.org/10.1515/zpch-2016-0813
Schlagwörter für diesen Artikel
cross loop resonator; electron spin relaxation; in vivo imaging; tumbling

Artikel in diesem Heft

  1. Frontmatter
  2. Preface
  3. Basic and Combination Cross-Features in X- and Q-band HYSCORE of the 15N Labeled Bacteriochlorophyll a Cation Radical
  4. An EPR Study of Small Magnetic Nanoparticles
  5. Magnetic Resonance Study of the Spin-1/2 Quantum Magnet BaAg2Cu[VO4]2
  6. Triarylmethyl Radicals: An EPR Study of 13C Hyperfine Coupling Constants
  7. Natural Abundance Nitrogen-15 NMR in Thermotropic Liquid Crystals With Cyano-Group
  8. Surface Hydroxyl OH Defects of η-Al2O3 and χ-Al2O3 by Solid State NMR, XRD, and DFT Calculations
  9. THz ESR study of Spinel Compound GeCo2O4
  10. Self-Association of Glycyrrhizic Acid. NMR Study
  11. A Site-Specific Study of the Magnetic Field-Dependent Proton Spin Relaxation of an Iridium N-Heterocyclic Carbene Complex
  12. Multifrequency Multiresonance EPR Investigation of Halogen-bonded Complexes Involving Neutral Nitroxide Radicals
  13. Electron Paramagnetic Resonance and DFT Analysis of the Effects of Bulky Perfluoroalkyl Substituents on a Vanadyl Perfluoro Phthalocyanine
  14. Coordination of the Mn4+-Center in Layered Li[Co0.98Mn0.02]O2 Cathode Materials for Lithium-Ion Batteries
  15. 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
Jetzt anmelden und 20% sparen
Institutioneller Zugang
Wie funktioniert Authentifizierung?
Haben Sie eine Idee, wie wir unsere Website verbessern können?
Bitte schreiben Sie uns.
© 2025 De Gruyter Brill
Heruntergeladen am 10.12.2025 von https://www.degruyterbrill.com/document/doi/10.1515/zpch-2016-0813/html
Button zum nach oben scrollen