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1.
Cell Struct Funct ; 39(2): 125-33, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25319070

RESUMEN

Here we describe the design and synthesis of a bifunctional two-photon fluorescence probe, N,N'-|dimethyl-4,4'-(biphenyl-2,1-ethenediyl)dipyridinium hexafluorophosphate (BP6). HeLa, Hek293, and Paramecium caudatum cells were stained with BP6. BP6 accumulated on the mitochondria of all three cell types when the mitochondrial membrane potential was high. As the mitochondrial membrane potential decreased following the addition of carbonyl cyanide m-chlorophenyl hydrazine, BP6 moved from the mitochondria to the nucleus in a reversible manner, depending on the mitochondrial membrane potential status. The maximum value of the two-photon absorption cross-section of BP6 is 250 GM (1 GM=1×10(-50) cm(4) s molecules(-1) photon(-1)). This value is 3 and 30 times larger, respectively, than that of the conventional mitochondria selective probes, rhodamine 123 and green fluorescence protein. These results suggest that BP6 should be useful for monitoring mitochondrial membrane potential by two-photon excitation.


Asunto(s)
Compuestos de Bifenilo/química , Colorantes Fluorescentes/química , Potencial de la Membrana Mitocondrial , Compuestos de Piridinio/química , Compuestos de Bifenilo/metabolismo , Colorantes Fluorescentes/metabolismo , Células HEK293 , Células HeLa , Humanos , Microscopía Fluorescente , Paramecium caudatum/citología , Fotones , Compuestos de Piridinio/metabolismo , Espectrometría de Fluorescencia , Coloración y Etiquetado
2.
J Nanosci Nanotechnol ; 14(4): 2895-900, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24734707

RESUMEN

Organic molecules adsorbed on an inorganic nanosheet often form a nanometer-sized cluster. In this study, we propose novel strategy for controlling the cluster size. We fabricated hybrid Langmuir-Blodgett (LB) films consisting of N-n-octadecyl-4-[2-(4-dimethylaminophenyl)ethenyl]-pyridinium bromide and a clay mineral, sodium montmorillonite, with varying subphase temperature. As a result, the size of the clusters was found to be decreased from 300 nm to 50 nm by increasing the subphase temperature from 10 degrees C to 40 degrees C.

3.
J Nanosci Nanotechnol ; 9(1): 658-61, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19441365

RESUMEN

The interaction of three photoactive organic dyes, Rhodamine B, Rhodamine 6G and a stilbazolium derivative 4'-dimethylamino-N-methyl-4-stilbazolium with synthetic sodium-saponite has been examined by UV-visible absorption spectroscopy. In all cases, bathochromic shifts and the reduction of peak absorbance for the dyes were observed in the absorption spectra at a low dye concentration (25% adsorption of the cation exchange capacity (CEC) of the clay), although the shape and the width of their absorption bands were similar to those in aqueous solution. This absorption behavior indicates that the organic dye molecules adsorbed onto the surface of the negatively charged clay particles and the adsorbed molecules were well dispersed. The photodegradation of the organic dyes in aqueous solution and in the clay suspension has been also examined by the irradiation of a laser beam at a wavelength of 532 nm. We have found that the hybridization of the organic dyes with the exfoliated clay particles largely enhanced a photodegradation. The clay particles acted as a catalyst even at a high concentration such as approximately 300% of CEC.

4.
J Phys Chem A ; 112(23): 5198-207, 2008 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-18481839

RESUMEN

Two-photon absorption (TPA) properties of newly synthesized conjugated ketone derivatives that include nonalternant azulenyl moieties in the pi-conjugation system, alpha,alpha'-bis(1-azulenylidene)cyclopentanone (1Az), alpha,alpha'-bis(2-azulenylidene)cyclopentanone (2Az), and alpha,alpha'-bis(6-azulenylidene)cyclopentanone (6Az) are reported. TPA spectra of these azulenyl compounds were measured using the open-aperture Z-scan method with a femtosecond laser. The TPA cross section at the peak position (sigma(2)peak) of 1Az was found to be the largest among the three azulenyl compounds, which is almost 7 times larger than that of the alpha,alpha'-bis(1-naphthylidene)cyclopentanone (1Nph), an alternant isomer of 1Az with the same number of pi-electrons. The small detuning energies of the azulenyl compounds compared to those of 1Nph were responsible for the large TPA cross sections. We report that a compound having an azulenyl moiety can be a promising TPA material.


Asunto(s)
Azulenos/química , Cetonas/química , Fotones , Absorción , Ciclopentanos/química
5.
ACS Appl Mater Interfaces ; 10(23): 19889-19896, 2018 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-29767503

RESUMEN

Tungsten oxide-based photochromic films that change reversibly in air between colorless-transparent in the dark and dark blue under UV irradiation were prepared by using methylcellulose as a film matrix and various dispersants. Alpha-hydroxyl acid such as glycolic acid (GA) or glyceric acid (GlyA) is the best dispersant because it can make the film transparent by adding a small quantity much less than that of 3-hydroxypropionic acid or ethylene glycol. Fourier-transform infrared spectra and Raman spectra indicate that a strong interaction exists between WO3 and GA or GlyA. The coloration and bleaching processes of the prepared films were investigated to clarify the effect of the dispersants and the moisture contents. The bleaching rate remarkably decreased in the films containing GA or GlyA but accelerated by increasing the contact with O2. Measurements of electron-spin resonance reveals that GA and GlyA as dispersants stabilize the W5+ state. This paper shows that the coloring rate and the period for keeping the blue-colored state are tunable by changing the dispersants. The photochromic films containing α-hydroxyl acid as the dispersant have the potential for application as rewritable film on which information displayed with blue-colored state can be clearly readable for longer times compared with other dispersants.

6.
Sci Rep ; 7(1): 7651, 2017 08 09.
Artículo en Inglés | MEDLINE | ID: mdl-28794416

RESUMEN

We propose a methodology for applying a pseudo uniaxial pressure to an organic molecule under ordinary temperature and pressure, namely by intercalation into smectites. The pseudo pressure on a biphenyl derivative (BP) was estimated from the averaged dihedral angle around the central bond of BP. In a high hydrostatic pressure field, biphenyl takes a planar conformation. In the interlayer space of synthetic saponite (SSA), the averaged dihedral angle of BP at a loading level of 27% versus the cation exchange capacity was ~26.3°, which indicates that the pseudo pressure applied to BP in the SSA interlayer space corresponds to 0.99 GPa. The high pseudo-pressure field in the interlayer space of SSA was also confirmed by absorption measurements. The dihedral angle around the central bond of the biphenyl moiety decreased to enhance the planarity of the molecule, mainly in response to the electrostatic force that operates between the negatively charged SSA layer and the interlayer cation. The pseudo pressure operating on BP in the smectite interlayer space could be controlled by varying the smectite layer charge density and/or the BP loading level. By using this methodology, controllable pseudo high-pressure properties of organic molecules can be obtained at ordinary temperatures and pressures.

7.
Curr Pharm Biotechnol ; 13(14): 2649-54, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22039816

RESUMEN

We have examined optical properties of a fluorene derivative with two positively charged substituents, 1,1'- diethyl-4,4'-(9,9-diethyl-2,7-fluorenediyl-2,1-ethanediyl)dipyridinium perchlorate (1), in water. The photoluminescence quantum yield of 1 was relatively high (35%) for use as a fluorescent probe in water. We also examined two-photon absorption (TPA) properties of 1 in methanol. The maximum value of the TPA cross-section (730 GM at 750 nm, 1 GM = 10(-50) cm4 s photon-1 molecule-1) was larger than that for most two-photon-excited fluorescent dyes including a classical mitochondria-selective fluorescent dye rhodamine 123. Preliminary fluorescence imaging experiments of the mitochondria in living Paramecium caudatum and HeLa cells were carried out with 1. Bright green fluorescence was observed from the mitochondria in both living cells loaded 1 without toxicity effects. These our results indicate that water-soluble fluorene derivative 1 is a promising candidate as a two-photon-excited fluorescence probe for mitochondria in living cells.


Asunto(s)
Fluorenos/farmacología , Mitocondrias/metabolismo , Paramecium caudatum/metabolismo , Absorción , Fluorenos/química , Colorantes Fluorescentes/farmacología , Células HeLa , Humanos , Indoles/farmacología , Microscopía Fluorescente , Fotones
8.
Nucleic Acids Res Suppl ; (2): 61-2, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12903105

RESUMEN

Solution structures of the 1:1 complexes of an alkyl-linked bis(benzimidazole) compound (4; Figure 1(a)) with the self-complementary DNA duplexes, d(CGCGAATTCGCG)2 and d(CGCAAATTTGCG)2, have been studied by 1H NMR spectroscopy and molecular mechanics calculations. The intermolecular NOE data and the energy-minimized geometries of the 1:1 complexes indicate that 4 binds in the minor groove of the 5'-GAATTCG and 5'-CAAATTT regions of the DNA duplexes.


Asunto(s)
Bencimidazoles/química , ADN/química , Secuencia de Bases , Conformación Proteica , Soluciones
9.
Nucleic Acids Res Suppl ; (2): 193-4, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12903171

RESUMEN

We have studied the influence of terminal substituents, amidinium group and N-methylpiperazine ring, of 2-phenylbenzimidazole compounds (1-6; Figure 1) on their DNA-binding modes. Experimental results reveal that 1-3 are accepted in intercalation pockets owing to structural flexibility of the N-methylpiperazine ring, while 4-6 bind to the groove of DNA because of steric hindrance between the amidinium group and the DNA phosphate-sugar backbone.


Asunto(s)
Bencimidazoles/química , ADN/química , Dicroismo Circular , Espectrofotometría Ultravioleta
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