Oxygen-derived free radicals: Production, biological importance, bioimaging, and analytical detection with responsive luminescent nanoprobes

Oxygen-derived free radicals (ODFRs) are partially reduced oxygen reactive intermediates in living organisms during various biological processes, such as mitochondrial respirations, enzyme-catalyzed oxidations, and radiolysis. Of various ODFRs being identified, superoxide anion (O-2(center dot-)) and hydroxyl (center dot OH) radicals are extensively investigated. Due to their high reactivity, these radicals can oxidize many biomolecules, including nucleic acids, proteins, lipids, and carbohydrates, which would damage some key cellular components. Under oxidative stress, elevated oxygen radical levels are closely associated with various diseases, such as neurodegenerative diseases, cardiovascular diseases, rheumatoid arthritis, and cancers. In this context, a number of responsive nanoprobes have been developed for luminescent detection of ODFRs in living organisms. In this review, we briefly introduce the production of ODFRs and their biological importance for various diseases. We then extensively summarize responsive nanoprobes for detection and bioimaging of these two oxygen radicals, O-2(center dot-) and center dot OH, which are designed and developed based on their specific oxidation mechanisms in the recent decade. Challenges and some future research directions are also proposed as the conclusion.

Automated summary

Oxygen-derived free radicals are partially reduced oxygen reactive intermediates in living organisms, which can oxidize biomolecules and are closely associated with various diseases. Responsive nanoprobes have been developed for detection and bioimaging of these radicals, providing new directions for future research.