Imaging Reactive Oxygen Species-Induced Modifications in Living Systems

Abstract

Significance: Reactive Oxygen Species (ROS) may regulate signaling, ion channels, transcription factors, and biosynthetic processes. ROS-related diseases can be due to either a shortage or an excess of ROS. Recent Advances: Since the biological activity of ROS depends on not only concentration but also spatiotemporal distribution, real-time imaging of ROS, possibly in vivo, has become a need for scientists, with potential for clinical translation. New imaging techniques as well as new contrast agents in clinically established modalities were developed in the previous decade. Critical Issues: An ideal imaging technique should determine ROS changes with high spatio-temporal resolution, detect physiologically relevant variations in ROS concentration, and provide specificity toward different redox couples. Furthermore, for in vivo applications, bioavailability of sensors, tissue penetration, and a high signal-to-noise ratio are additional requirements to be satisfied. Future Directions: None of the presented techniques fulfill all requirements for clinical translation. The obvious way forward is to incorporate anatomical and functional imaging into a common hybrid-imaging platform. Antioxid. Redox Signal. 24, 939–958.

Vitamin E: Regulatory Redox Interactions

“…It has also been reported that two α‐Toc• form poorly reactive non‐radical dimers (Fig. (15)) . The lipid peroxidation reaction introduced above can be expressed as a rate constant ( k ) using a two‐compartment kinetic model equation (Fig.…”

Mitochondrial Dysfunction and Redox Imbalance as a Diagnostic Marker of “Free Radical Diseases”

“…Since only the radical form is characterized by EPR/MRI contrast, this could be used as a quantitative marker for the as-sessment of the redox status in biological objects in vitro and in vivo (91). Many excellent review articles have described this possibility (92,(95)(96)(97)(98).…”

Taking up the cudgels for the traditional reactive oxygen and nitrogen species detection assays and their use in the cardiovascular system

“…much more sensitive electrochemical detection of the DHE products) or new DHE analogs allowing sitespecific detection of superoxide (e.g. mito-SOX for mitochondrial superoxide and hydropropidine for extracellular superoxide) or the most advanced new spin traps providing higher stability in biological samples and thereby allow the EPR-based detection of superoxide and/ or peroxynitrite-derived free radicals in cells and tissues (some candidates might be found in [32,[135][136][137]). High performance liquid chromatography (HPLC)-based detection of superoxide formation in the extracellular space, cytosol and mitochondria can be established by hydropropidine, a positively-charged water-soluble analogue of dihydroethidium (DHE) for extracellular superoxide formation [138], DHE for cytosolic superoxide formation and mitoSOX, a mitochondria-targeted DHE analogue for mitochondrial superoxide formation (Fig.…”

“…Combined with the respective spin trap, these techniques have the potential for the specific detection of vascular ROS and RNS formation in isolated tissues and whole animals [135,154]. Also combination of different techniques such as immuno-spin trapping as reported for trapping of thiyl radical in proteins or other radicals in DNA by DMPO and formation of stable spin-adducts with subsequent Western blotting against DMPO-bound proteins or DNA molecules are already used for the detection of ROS and RNS formation, or more precisely their footprints in biological samples [155].…”

“…Also combination of different techniques such as immuno-spin trapping as reported for trapping of thiyl radical in proteins or other radicals in DNA by DMPO and formation of stable spin-adducts with subsequent Western blotting against DMPO-bound proteins or DNA molecules are already used for the detection of ROS and RNS formation, or more precisely their footprints in biological samples [155]. Delivery of chemiluminescent or fluorescent nanoparticles or nanoparticles loaded with specific ROS and RNS detection probes might provide the next step in oxidative stress and redox biology research (reviewed in [135] and for drug delivery in [156]). Also the delivery of specific dyes and/or ROS and RNS scavengers bound to specific antibodies, as already done for sitespecific drug delivery [17,157], in order to target specific cellular structures, organelles or sites of inflammation might be a strategy that will become relevant in the future.…”