Browsing by Author "Fuentealba, Denis"

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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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    Memantine biotin conjugate with intra tumoral cell displacing ability for cucurbit[8]uril-based switchable photosensitizer
    (Elsevier B.V., 2025) González Torres, Diego Ariel; Zúñiga Nuñez, Daniel; Mariño Ocampo, Nory Johana; Díaz Canals, Martin Rodrigo; Muñoz, Constanza; Guerra Díaz, Daniel; Soto Arriaza, Marco; Fuentealba, Denis
    Switchable supramolecular photosensitizers have the potential to be more potent and decrease common side effects of photodynamic therapy such as patient's sensitivity to ambient light. Combining this supramolecular strategy with a cancer-targeting strategy would also improve selectivity towards tumoral cells. In this work, we take advantage of the strong binding ability of cucurbit[8]uril towards cationic photosensitizer methylene blue. Encapsulation of two molecules of methylene blue inside the cavity of cucurbit[8]uril leads to strong quenching of its photoactivity, particularly the generation of singlet oxygen. In order to release selectively the photosensitizer, we synthesized a new memantine-biotin conjugate that is able to cross a liposomal bilayer as a model for a biological membrane and bind to cucurbit[8]uril releasing the photosensitizer. This phenomenon leads to a sizable boost in singlet oxygen generation. In vitro phototoxicity studies in tumoral cells show a significant difference in cell killing after the addition of the memantine-biotin displacing agent. These studies have important potential for more selective photodynamic therapy of cancer.
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    New Benzotriazole and Benzodithiophene-Based Conjugated Terpolymer Bearing a Fluorescein Derivative as Side-Group: In-Ternal Forster Resonance Energy Transfer to Improve Organic Solar Cells
    (MDPI, 2022) Jessop, Ignacio A.; Cutipa, Josefa; Perez, Yasmin; Saldias, Cesar; Fuentealba, Denis; Tundidor-Camba, Alain; Terraza, Claudio A.; Camarada, Maria B.; Angel, Felipe A.
    A new benzodithiophene and benzotriazole-based terpolymer bearing a fluorescein derivative as a side group was synthesized and studied for organic solar cell (OSC) applications. This side group was covalently bounded to the backbone through an n-hexyl chain to induce the intramolecular Forster Resonance Energy Transfer (FRET) process and thus improve the photovoltaic performance of the polymeric material. The polymer exhibited good solubility in common organic chlorinated solvents as well as thermal stability (TDT10% > 360 degrees C). Photophysical measurements demonstrated the occurrence of the FRET phenomenon between the lateral group and the terpolymer. The terpolymer exhibited an absorption band centered at 501 nm, an optical bandgap of 2.02 eV, and HOMO and LUMO energy levels of -5.30 eV and -3.28 eV, respectively. A preliminary study on terpolymer-based OSC devices showed a low power-conversion efficiency (PCE) but a higher performance than devices based on an analogous polymer without the fluorescein derivative. These results mean that the design presented here is a promising strategy to improve the performance of polymers used in OSCs.
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    Removal of chlorpyrifos from water using biosorbents derived from cassava peel, crambe meal, and pinus bark
    (2022) Schwantes, Daniel; Goncalves Jr, Affonso Celso; Fuentealba, Denis; Carneiro, Maria Fernanda Hornos; Tarley, Cesar Ricardo Teixeira; Prete, Maiyara Carolyne
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    Supramolecular complex of tetracationic porphyrin with acyclic cucurbituril-like container induces quantitative singlet oxygen generation. Phototoxicity studies in vitro in MCF-7 human breast cancer cells
    (2024) Day, Skarlett; Pérez, Benjamín; Guerra Díaz, Daniel; Mariño-Ocampo, Nory; Zúñiga-Núñez, Daniel; Faúndez, Mario A.; Soto-Arriaza, Marco; Pizarro, Nancy; Heyne, Belinda; Fuentealba, Denis
    Singlet oxygen generation by porphyrin-based photosensitizers is one of the main strategies used in the photodynamic therapy of cancerous lesions. In this work, we report that the complexation of tetracationic 5,10,15,20-tetrakis(N-methylpiridinium-4-yl)porphyrin (TMPyP) with an acyclic cucurbituril-like container denominated M2C4 achieves quantitative generation of singlet oxygen. The complexation was studied by isothermal titration calorimetry, revealing a highly favored binding event controlled by enthalpic contributions, a stoichiometry of 1:1 and a high binding constant (K = (1.7 ± 0.2) × 107 M−1). Photophysical studies of the complex showed bathochromic shifts in the absorption bands, increased fluorescence emission quantum yield and lengthened fluorescence lifetime. Nonetheless, fluorescence emission was minor, being intersystem crossing with the consequent generation of singlet oxygen the main deactivation pathway for the excited state. All these properties were compared with the previously reported TMPyP and cucurbit[7]uril (CB[7]) complex, which showed a superiority of the acyclic complex in terms of quantum efficiencies. Phototoxicity studies in a breast cancer cell line (MCF-7) cultured in vitro, showed that the TMPyP@M2C4 complex is unable to enter the cells even after a 24 h incubation period. However, this issue could be circumvented by encapsulating the complex into liposomes which delivered the complex to the cells efficiently. Overall, this strategy showed good potential for a highly efficient photodynamic treatment using the TMPyP@M2C4 complex in liposomal formulations.