The Ability of Functionalized Fullerenes and Surface-Modified TiO Nanoparticles to Photosensitize Peroxidation of Lipids in Selected Model Systems.

Photochemical properties of a new class of inorganic nanoparticles, namely a cationic C fullerene substituted with three quaternary pyrrolidinium groups (BB6) and a surface-modified nanocrystalline TiO with bromopyrogallol red (Brp@TiO ) were examined for their effectiveness in photogenerating singlet oxygen and free radicals. In particular, their ability to photosensitize peroxidation of unsaturated lipids was analyzed in POPC:cholesterol liposomes and B16 mouse melanoma cells employing a range of spectroscopic and analytical methods. Because melanoma cells typically are pigmented, we examined the effect of melanin on the photosensitized peroxidation of lipids in liposomes and B16 melanoma cells, mediated by BB6 and Brp@TiO nanoparticles.

Antimicrobial photodynamic inactivation is potentiated by the addition of selenocyanate: Possible involvement of selenocyanogen?

We previously showed that antimicrobial photodynamic inactivation (aPDI) of Gram-positive and Gram-negative bacteria mediated by the phenothiazinium dye, methylene blue (MB), was potentiated by the addition of potassium thiocyanate (10 mM). The mechanism was suggested to involve a singlet oxygen-mediated reaction with SCN to form sulfite and cyanide and then to produce sulfur trioxide radical anion. We now report that potassium selenocyanate (concentrations up to 100 mM) can also potentiate (up to 6 logs of killing) aPDI mediated by a number of different photosensitizers (PS): MB, rose bengal and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin dihydrochloride (as low as 200 nM).

Photoaging of retinal pigment epithelial melanosomes: The effect of photobleaching on morphology and reactivity of the pigment granules.

To elucidate the mechanism of age-related changes in antioxidant and photoprotective properties of human retinal pigment epithelium (RPE) melanosomes, the effect of in vitro photoaging of bovine RPE melanosomes was examined employing an array of complementary spectroscopic and analytical methods. Electron paramagnetic resonance (EPR) spectroscopy, saturation recovery EPR, atomic force microscopy (AFM) and dynamic light scattering (DLS) were used to determine melanin content of control and photobleached melanosomes, and to monitor changes in their morphology. Methylene blue (MB), TEMPO choline, dysprosium(III) ions and singlet oxygen were employed as molecular probes to characterize the efficiency of control and photobleached melanosomes to interact with different reagents.

Thiocyanate potentiates antimicrobial photodynamic therapy: in situ generation of the sulfur trioxide radical anion by singlet oxygen.

Antimicrobial photodynamic therapy (PDT) is used for the eradication of pathogenic microbial cells and involves the light excitation of dyes in the presence of O2, yielding reactive oxygen species including the hydroxyl radical (OH) and singlet oxygen ((1)O2). In order to chemically enhance PDT by the formation of longer-lived radical species, we asked whether thiocyanate (SCN(-)) could potentiate the methylene blue (MB) and light-mediated killing of the gram-positive Staphylococcus aureus and the gram-negative Escherichia coli. SCN(-) enhanced PDT (10 µM MB, 5 J/cm(2) 660 nm hv) killing in a concentration-dependent manner of S.