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S Nonell

Publications and source records attributed to S Nonell.

8 recordsLinked to original sources
PubMed2000

Photophysical properties of neutral and cationic tetrapyridinoporphyrazines.

We describe the synthesis and photophysical properties of a series of neutral and cationic 3,4-tetrapyridinoporphyrazines, potential lead photosensitizers for photodynamic inactivation of bacteria. Tetracationic TPyPzs exist essentially as monomers in aqueous systems, but the presence of trialkylated compounds due to incomplete quaternization of the outer nitrogen atoms induces severe aggregation. The absorption, fluorescence, triplet, and singlet oxygen quantum yields for both the neutral and cationic compounds are comparable to those of the related phthalocyanines.

Cations↗
PubMed2000

Photosensitizing properties of palladium-tetraphenylporphycene on cultured tumour cells.

In this study we describe photokilling properties and effects on the mitotic index (MI) of cultured HeLa cells induced by palladium(II)-tetraphenylporphycene (PdTPP(0)). The drug was synthesized by refluxing tetraphenylporphycene (TPP(0)) and PdCl2 in dimethylformamide, followed by evaporation and purification by chromatography. Cells were treated with different concentrations of PdTPPo incorporated into dipalmitoylphosphatidylcholine liposomes, and red light irradiation (lambda > 600 nm) was performed at 21 mW/cm2. No dark toxicity was found when the drug was applied under our experimental conditions. Using lethal (LD(100)) treatments, cells showed the immediate occurrence of bubbles on the plasma membrane, whereas homogeneous nuclear condensation and loss of cytoplasm appeared 3-24 h later. An increased MI was found 6-8 h after sublethal LD(25) and LD(40) treatments as well as a high proportion of abnormal metaphases with altered spindle microtubules. Chromatin condensation and fragmentation were observed 8 h after LD(75) treatments. These results show that in comparison with TPP(0), the new sensitizer PdTPPo has more efficient photokilling properties which could be very valuable for the photodynamic therapy of cancer.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1997

Uptake of tetraphenylporphycene and its photoeffects on actin and cytokeratin elements of HeLa cells.

In the present work we have continued our studies in the photobiological properties of the 2,7,12,17-tetraphenylporphycene (TPPo). In particular, the uptake, the subcellular localization and the photoeffects on two cytoskeletal elements (actin, microfilaments and cytokeratin intermediate filaments) of HeLa cells have been analyzed. The uptake kinetics of TPPo, determined by fluorescence spectroscopy, was initially very rapid, reaching saturation at approximately 6 h of incubation. This porphycene tends to be accumulated mainly in rounded particles distributed throughout the cytoplasm. The morphological comparison of the localization pattern of TPPo and those of acridine orange and rhodamine 123, which are fluorescence markers for lysosomes and mitochondria respectively, allowed us to confirm that this porphycene is mainly accumulated in lysosomal organelles. The results obtained after treatment with TPPo and red light indicated that this compound is very effective in mediating the photodestruction of lysosomes. The photosensitizing effects on the cytoskeletal elements studied depended on both the irradiation time and the elapsed time after treatment. The implications of damage to lysosomes and actin and cytokeratin filaments on the process of cell death is discussed.

Acridine Orange↗
PubMed1996

Photodamaging effects of tetraphenylporphycene in a human carcinoma cell line.

The photosensitizing effects of tetraphenylporphycene (TPPo) and light on HeLa cells, with emphasis on cell viability and the microtubular network, have been investigated. The survival of the cells incubated with TPPo was dependent on both drug concentration and light dose. The integrity of microtubules (MTs) was evaluated by immunofluorescence staining of alpha-tubulin. Interphasic and mitotic MTs were altered after 30 min of incubation with 5 microM TPPo followed by light irradiation. The degree of damage depended on light exposure time: 3 or 15 min corresponded to survival rates of approximately 50% or < 5%, respectively. Sublethal treatment led to the gradual accumulation of cells in metaphase, which caused an increase in the mitotic index (MI), with a maximum being found 6 h later. The number of cells in metaphase, as well as the MI, were within control values 24 h after sublethal photodynamic treatment. Lethal treatment provoked irreversible damage of interphasic and mitotic MTs. In addition, cell surface modifications such as bleb projections of the plasma membrane were also observed immediately after lethal treatment. It is concluded that both cellular structures, plasma membrane and MTs, constitute important targets for the phototoxic action of TPPo.

Cell Survival↗
PubMed1990

Quantum yield of production of singlet molecular oxygen (1 delta g) in aqueous dispersions of small unilamellar lipid vesicles. A time-resolved near-IR phosphorescence study.

The quantum yield of formation and kinetic behaviour of O2(1 delta g) in D2O dispersions of small unilamellar vesicles (SUVs) of dipalmitoyl phosphatidylcholine were studied by time-resolved detection of near-IR phosphorescence. At a SUV concentration of 26 nM, O2(1 delta g) is not quenched by the vesicles. It diffuses quickly through the lipid bilayer and a partition equilibrium of O2(1 delta g) between the lipid bilayer and the buffer is attained before decay occurs. In this equilibrium situation O2(1 delta g) is mostly located in the buffer phase, which permits the determination of absolute quantum yields for O2(1 delta g) production, phi delta, by comparison of the luminescence in the dispersions with that in neat D2O. The maximal phi delta values for the sensitizers incorporated in the SUV bilayer were 0.47 +/- 0.09 for the dipyridyl complex of zinc(II) phthalocyanine (ZnPc), 0.35 +/- 0.08 for porphycene, and 0.36 +/- 0.08 for 2,7,12,17-tetra-n-propylporphycene. These values are equal to those in neat organic solvents but lower than those previously obtained in SUVs by using chemical trapping agents. The high degree of organization of the environment around the sensitizers does not influence their efficiency of producing O2(1 delta g). While no concentration dependence is observed for ZnPc (at least up to a local concentration of 20 mM in the bilayer), phi delta for both porphycenes significantly decreases above a local concentration of 4 mM in the bilayer. This result is expected in view of previous observations on the concentration dependence of other photophysical parameters of the porphycenes in such microheterogeneous media.

1,2-Dipalmitoylphosphatidylcholine↗