ChemInform Abstract: Singlet Oxygen: There Is Indeed Something New under the Sun

Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Arhus, Denmark.
Chemical Society Reviews (Impact Factor: 33.38). 08/2010; 39(8):3181-209. DOI: 10.1039/b926014p
Source: PubMed


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).

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    • "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 "
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    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.
    Marine Chemistry 02/2015; 171. DOI:10.1016/j.marchem.2015.02.007 · 2.74 Impact Factor
    • "In addition, the transition dipole moments of the donor and acceptor must not be perpendicular — otherwise the transfer efficiency is zero, irrespective of the donor—acceptor distance or the spectral overlap. Finally, the multiplicity must be preserved by the transitions, singlet-triplet transitions are forbidden as they require a spin flip (Sauer et al., 2011) (in this context, note that the important singlet oxygen generation in photodynamic therapy (Ogilby, 2010), or as one of the photobleaching processes, by energy transfer from the fluorophore's triplet state occurs via Dexter-type electron exchange which does not need to conserve multiplicities (Dexter, 1953)). The critical transfer distance R 0 , where FRET and fluorescence emission are equally likely, can be calculated 3 from the spectral overlap integral J F (Dixon et al., 2005; Du et al., 1998) according to "
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    ABSTRACT: Fluorescence lifetime imaging (FLIM) is a key fluorescence microscopy technique to map the environment and interaction of fluorescent probes. It can report on photo physical events that are difficult or impossible to observe by fluorescence intensity imaging, because FLIM is independent of the local fluorophore concentration and excitation intensity. A FLIM application relevant for biology concerns the identification of FRET to study protein interactions and conformational changes, and FLIM can also be used to image viscosity.
    Springer Series in Chemical Physics 01/2015; 111:119-188. DOI:10.1007/978-3-319-14929-5_3
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    • "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. "
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    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.
    Journal of Dairy Science 11/2014; 98(1). DOI:10.3168/jds.2014-8691 · 2.57 Impact Factor
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