Article

Redox Mapping of Biological Samples Using EPR Imaging

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Abstract

Under normal conditions, cells meticulously maintain redox homeostasis. However, under abnormal conditions, such as stress, the redox equilibrium is disturbed, leading to a threat to the cellular wellbeing. Techniques that are capable of measurement of the redox status might prove useful in the detection and treatment of adverse conditions that change the cellular redox equilibrium. Electron paramagnetic resonance (EPR) imaging is a unique non-invasive imaging technique that is capable of redox measurements in vivo. EPR utilizes redox-sensitive spin labels, nitroxides. These EPR-active probes are reduced by cellular reducing agents to EPR-inactive species (hydroxylamines). The rate of reduction, among various factors, depends on the redox status of the cell, thus providing information about the redox environment of the region of interest. This review focuses on the principle, method, and application of redox mapping to biological systems.

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... The possibility to perform the imaging in two-dimensions and three-dimensions enables the visualization of the spatial distribution of paramagnetic substances, namely spin probes, that are distributed in small laboratory animals, including mice [3,4], rats [5], and rabbits [6]. ERI is based on the EPR phenomenon and it allows for the mapping of tissue microenvironment parameters such as the level of oxygen (pO 2 ) [7,8], pH [9,10], inorganic phosphate [11] and redox state [12]. ...
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... Therefore, the possibility to additionally capture the inflow phase sheds new light on redox research, and it provides complete information about the imbalance between reduction and oxidation of nitroxide. 22,23,44 Comparison to Dynamic Contrast-Enhanced Imaging. Dynamic contrast-enhanced (DCE) imaging is associated with techniques that require the acquisition of a baseline image, which is acquired without any contrast enhancements, followed by a series of images acquired over time after an intravenous bolus of a contrast agent (CA). ...
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