Browsing by Author "Poblete, Horacio"

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    Antioxidant reactivity toward nitroxide probes anchored into human serum albumin. A new model for studying antioxidant repairing capacity of protein radicals
    (2009) Aspee, Alexis; Orrego, Alejandra; Alarcón Abarzúa, Emilio Isaac; López Alarcón, Camilo Ignacio; Poblete, Horacio; Gonzalez-Nilo, Danilo
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    Exploring the photophysics of cinnamoyl-coumarin derivatives in cucurbit [7]uril complexes and assessing phototoxicity in HeLa cells
    (2024) Zuniga-Nunez, Daniel; Mura, Francisco; Marino-Ocampo, Nory; Zuniga, Benjamin; Robinson-Duggon, Jose; Zamora, Ricardo A.; Poblete, Horacio; Aspee, Alexis; Fuentealba, Denis
    Cinnamoyl-coumarin derivatives containing 5 or 12 carbon aliphatic chains were evaluated as photosensitizers and their photophysical properties were studied in detail. Moreover, these compounds were encapsulated in cucurbit[7]uril macrocycle with relatively high binding affinities in aqueous media. Fluorescence quantum yields, fluorescence lifetimes and singlet oxygen quantum yields were measured upon encapsulation. Computational DFT calculations and molecular dynamics simulations allowed the visualization of the binding modes of both derivatives inside the macrocycle. In particular, the free energy profiles for the insertion of the molecules into the macrocycle were determined to assess the most probable conformations of the complexes in water. In vitro phototoxicity assays were carried out in HeLa cells showed significant decreases in cell viability upon illumination of the 5 carbon aliphatic chain derivative at 460 nm with an LED source at different concentrations and enhanced by cucurbit[7]uril. However, the one with 12 carbon aliphatic chain did not display any phototoxicity regardless of the presence of cucurbit[7]uril. This behavior is related to the high lipophilicity introduced by a 12 carbon aliphatic chain conditioning its distribution on hydrophobic compartments and decreasing its phototoxicity. The enhanced phototoxicity elicited by cucurbit[7]uril on the 5 carbon aliphatic chain derivative but not in the 12 carbon derivative remark that there is a balance between hydrophobicity of these probes with the carrier properties of cucurbit[7]uril to be reach for effective phototoxicity properties.
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    Photophysics and photochemistry of dyes bound to human serum albumin are determined by the dye localization
    (2010) Alarcón Abarzúa, Emilio Isaac; EdwardsM., Ana M; Aspee, Alexis; Moran Vieyra, Faustino Eduardo; Borsarelli, Claudio D.; Lissi, Eduardo A.; González Nilo, Fernando Danilo; Poblete, Horacio; Scaiano, J. C.
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    Time-resolved fluorescence and anisotropy-sensitive 1,2-dimyristoyl-sn-glycero-3-(7-aminocoumarin) phosphoetanolamide probe for studying membrane lipid domains
    (ELSEVIER SCI LTD, 2023) Zúñiga Núñez, Daniel; Mura, Francisco; Mariño-Ocampo, Nory; Briones-Rebolledo, Patricio; Poblete, Horacio; Mallet, Jean-Maurice; Fuentealba Patino, Denis Alberto; Aspee, Alexis
    A fluorescent probe C-DMPE was synthesised to monitor interfacial membrane properties by conjugating coumarin-343 and 1,2-dimyristoyl-sn-glycero-3-phosphorylethanolamine (DMPE), anchoring the 7-aminocou-marin moiety close to the phospholipid polar head at the membrane interface. Large unilamellar vesicles (LUV) of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), of 1,2-dioleyl-sn-glycero-3-phosphatidyl-choline (DOPC) and cholesterol were employed as a model of lipid bilayer. Time-resolved fluorescence developed an emissive Internal Charge Transfer excited state with a long fluorescence lifetime (T1), a Locally Excited state with an intermediate fluorescence lifetime (T2), and a short lifetime (T3) associated with an intermolecular quenching by interaction with a phosphate group of neighbour phospholipids, as is clearly shown by molecular dynamics simulations. Shorter values of fluorescence lifetimes T1 and T3 were observed in DOPC with respect to DPPC, responding to a more fluid membrane with more significant water accessibility in DOPC than DPPC. However, in DPPC:DOPC vesicles, these fluorescence lifetimes are even shorter, allowing to be attributed to favourable sensing of boundary limit lipid domains. In similitude, time-resolved anisotropy showed shorter rotational correlation times phi 1, in DPPC: DOPC vesicles than in DOPC associated with a faster internal rotational movement of the 7-aminocoumarin group in domains than in fluid a DOPC membrane. In addition, shorter rotational correlation times, (P2, were also observed in DPPC:DOPC vesicles compared to DPPC, suggesting a faster lateral diffusion of the probe in the presence of domains.