Imaging radio frequency electron-spin-resonance spectrometer with high resolution and sensitivity for i n v i v o measurements

Publisher Website
Google Scholar
Abstract
We report the development of a novel radio frequency electron‐spin‐resonance spectrometer designed to provide measurements with high molar sensitivity and resolution in vivo. Radio frequency (250 MHz) is chosen to obtain good penetration in animal tissue and large aqueous samples with modest sacrifice of sensitivity. The spectrometer has a lumped component resonator and operates in continuous‐wave mode. The spectrometer is capable of two‐dimensional imaging, and with a modest addition should be capable of three‐dimensional imaging. We demonstrate 3‐mm spatial resolution for DPPH samples. For 10‐ml samples of aqueous nitroxide, we demonstrate sensitivity (normalized to spectral width of 1 G) to 3×10−8‐M concentrations and spectral resolution of 0.1 G. Spectra from nitroxide spin label injected into a live mouse are shown.