Singlet oxygen, O(2)(a(1)Delta(g)), the lowest excited electronic state of molecular oxygen, has been known to the scientific community for approximately 80 years. It has a characteristic chemistry that sets it apart from the triplet ground state of molecular oxygen, O(2)(X(3)Sigma), and is important in fields that range from atmospheric chemistry and materials science to biology and medicine. For such a "mature citizen", singlet oxygen nevertheless remains at the cutting-edge of modern science. In this critical review, recent work on singlet oxygen is summarized, focusing primarily on systems that involve light. It is clear that there is indeed still something new under the sun (243 references).
"In the case of senescent phytoplanktonic cells, 1 O 2 can induce the degradation of heterotrophic bacteria attached to particles. Indeed, recent results demonstrated that singlet oxygen has a much larger intracellular sphere of activity than previously thought (Ogilby, 2010). Most of the calculated values of the radius of singlet oxygen's sphere of activity from its point of production (ranging from 155 to "
[Show abstract][Hide abstract] ABSTRACT: The effect of silica and carbonaceous matrices (charged mineral surfaces) in phytoplankton cells on the transfer of singlet oxygen from irradiated phytodetritus to their attached bacteria was investigated under controlled laboratory conditions. Our results indicate that a silica matrix (i.e. as in diatom frustules) inhibits the transfer of singlet oxygen and limits the induced photodegradation of cis-vaccenic acid (a fatty acid generally considered as specific to bacteria). In contrast, a carbonaceous matrix (i.e. as in coccoliths) does not seem to inhibit the transfer probably due to the release of coccoliths upon cell death. As a consequence, bacteria associated with phytodetritus from diatoms should be in a healthy state and biodegradation of organic matter associated with these particles should be favored. These results should contribute to a better understanding of photosensitized degradation processes and to a better estimation of the balance between degradation and preservation of organic material during sedimentation in seawater.
"Antibacterial photosensitization-based treatment (APBT) is an emerging methodology that relies on the combined action of an otherwise nontoxic molecule (called photosensitizer), visible light, and oxygen to produce cytotoxic effects by the photoinduced generation of reactive oxygen species (photodynamic effect), particularly singlet oxygen ( 1 O 2 ). Thus, photoexcitation of the photosensitizers leads to the formation of 1 O 2 , a nonradical, electronically excited form of the dioxygen molecule that is highly reactive against a vast array of cellular components ranging from membrane lipids to proteins and nucleic acids (Ogilby, 2010; Jori et al., 2011). The APBT has proved to be valuable for the treatment of localized microbial infections, effectively acting on several classes of microbial pathogens without inducing insurgence of photoresistant species even after multiple treatments. "
[Show abstract][Hide abstract] ABSTRACT: Using a combination of molecular modeling and spectroscopic experiments, the naturally occurring, pharmacologically active hypericin compound is shown to form a stable complex with the dimeric form of β-lactoglobulin (β-LG). Binding is predicted to occur at the narrowest cleft found at the interface between monomers in the dimeric β-LG. The complex is able to preserve the fluorescence and singlet oxygen photosensitizing properties of the dye. The equilibrium constant for hypericin binding has been determined as Ka = 1.40 ± 0.07 μM−1, equivalent to a dissociation constant, Kd = 0.71 ± 0.03 μM. The complex is active against Staphylococcus aureus bacteria. Overall, the results are encouraging for pursuing the potential application of the complex between hypericin and β-LG as a nanodevice with bactericidal properties for disinfection.
"Singlet molecular oxygen [O 2 ( 1 D g )] can be basically generated by light dependent and independent reactions  . Details on the several possible chemical and biochemical routes leading to O 2 ( 1 D g ) generation and its detection in cellular systems have been reviewed elsewhere   . Scheme 1 summarizes some of the major routes that could generate O 2 ( 1 D g ) in biological system. "
[Show abstract][Hide abstract] ABSTRACT: The chemistry behind the phenomenon of ultra-weak photon emission has been subject of considerable interest for decades. Great progress has been made on the understanding of the chemical generation of electronically excited states that are involved in these processes. Proposed mechanisms implicated the production of excited carbonyl species and singlet molecular oxygen in the mechanism of generation of chemiluminescence in biological system. In particular, attention has been focused on the potential generation of singlet molecular oxygen in the recombination reaction of peroxyl radicals by the Russell mechanism. In the last ten years, our group has demonstrated the generation of singlet molecular oxygen from reactions involving the decomposition of biologically relevant hydroperoxides, especially from lipid hydroperoxides in the presence of metal ions, peroxynitrite, HOCl and cytochrome c. In this review we will discuss details on the chemical aspects related to the mechanism of singlet molecular oxygen generation from different biological hydroperoxides.
Journal of Photochemistry and Photobiology B Biology 10/2014; 139. DOI:10.1016/j.jphotobiol.2014.03.028 · 2.96 Impact Factor
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