Proton-electron double-resonance imaging of pH using phosphonated trityl probe

Wataru Takahashi, Andrey A. Bobko, Ilirian Dhimitruka, Hiroshi Hirata, Jay L. Zweier, Alexandre Samouilov, Valery V. Khramtsov

Research output: Contribution to journalArticlepeer-review

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 the 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.

Original languageEnglish (US)
Pages (from-to)817-826
Number of pages10
JournalApplied Magnetic Resonance
Volume45
Issue number9
DOIs
StatePublished - Aug 17 2014
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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