Chapter 3: Water-Soluble Carriers of Singlet Oxygen for Biological Media

Water-soluble naphthalene derivatives bind reversibly singlet oxygen (¹O₂, ¹Δ_g) at neutral pH giving isolable endoperoxides NO₂. These nontoxic compounds release, upon moderate heating, well-defined amounts of ¹O₂ free from any other reactive contaminants. Therefore, they allow nonambiguous determination of the reactivity of ¹O₂ toward biological targets. This review focuses on the one hand, on synthetic strategies developed to prepare effective ¹O₂ carriers and, on the other hand, their use to assess the genuine reactivity of ¹O₂ toward molecular (lipids, amino acids, nucleosides) or macromolecular (DNA, proteins) targets as well as micro-organisms (virus, bacteria, cells). The advantages and limitations of these mild chemical sources ¹O₂ are compared to those of the conventional photosensitizing method used to generate ¹O₂.