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81.
Vargas F Zoltan T Rivas C Ramirez A Cordero T Díaz Y Izzo C Cárdenas YM López V Gómez L Ortega J Fuentes A 《Journal of photochemistry and photobiology. B, Biology》2008,92(2):83-90
We have synthesized two naphthyl ester quinolone derivates and determined their ability to generate reactive oxygen species (ROS) such as (1)O(2), ()OH, H(2)O(2) upon photolysis with UV-A light. The ability of cinoxacin (1) and nalidixic acid (2), and their naphthyl ester derivatives (3 and 4) to generate a dose-dependent amount of singlet oxygen and ROS (()(-)O(2), ()OH) in cell-free systems was detected by histidine assay and by luminol-enhanced chemiluminescence (LCL), respectively. Their electronic absorption and emission spectra were quantified and their photostability was determined. Their tendency to generate peroxidic derivative species showed the following order: 3>4; in contrast, their ability to generate singlet oxygen was 4>3 and these were better sensitizers than their parent quinolones 1 and 2. The antibacterial activity in darkness and under irradiation of compounds 3 and 4 was tested on Escherichia coli and compared with that of their parent compounds. An enhanced antibacterial activity by irradiation of the naphthyl esters of cinoxacin and nalidixic acid on E. coli was observed. 相似文献
82.
C. Mateo-Mateo C. Vázquez-Vázquez M.C. Buján-Núñez M.A. López-Quintela D. Serantes D. Baldomir J. Rivas 《Journal of Non》2008,354(47-51):5236-5237
Cobalt ferrite–poly(N-vinyl-2-pyrrolidone) nanocomposites were prepared by drying a dispersion of cobalt ferrite (CoFe2O4) nanoparticles and poly(N-vinyl-2-pyrrolidone). Magnetic measurements indicate a superparamagnetic behavior. Zero-field-cooling magnetization experiments at 100 Oe show different trends depending on the CoFe2O4 nanoparticles size. For the smaller ones (3.9 nm), the blocking temperatures shift to lower temperatures with increasing concentration; however, this shift is not observed for the larger ones (6.6 nm). These differences can be related to the anisotropy constant of the CoFe2O4 nanoparticles and the interparticle dipolar interactions. 相似文献
83.
Optical control over surface-plasmon-polariton-assisted THz transmission through a slit aperture 总被引:1,自引:0,他引:1
Hendry E Garcia-Vidal FJ Martin-Moreno L Rivas JG Bonn M Hibbins AP Lockyear MJ 《Physical review letters》2008,100(12):123901
We demonstrate optical control over the transmission of terahertz (THz) radiation through a single subwavelength slit in an otherwise opaque silicon wafer. The addition of periodic corrugation on each side of the wafer allows coupling to surface plasmon polaritons, so that light not impinging directly on the slit can contribute to the transmission. A significant enhancement of the THz transmission can be achieved through control of the surface wave propagation length by excitation at optical wavelengths. The observed transmission increase is in distinct contrast to the reduction reported for photoexcitation of arrays of holes in semiconductors. 相似文献
84.
Electrochemical Sensor for the Quantification of Dopamine Using Glassy Carbon Electrodes Modified with Single‐Wall Carbon Nanotubes Covalently Functionalized with Polylysine
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Alejandro Gutiérrez Aurélien Gasnier María L. Pedano Jose Miguel Gonzalez‐Dominguez Alejandro Ansón‐Casaos Javier Hernández‐Ferrer Laura Galicia María D. Rubianes María T. Martínez Gustavo A. Rivas 《Electroanalysis》2015,27(7):1565-1571
We report a dopamine electrochemical sensor based on the modification of glassy carbon electrodes (GCE) with polylysine‐functionalized single‐wall carbon nanotubes (SWCNT‐PLys). The resulting electrodes (GCE/SWCNT‐PLys) showed a significant improvement in the electrooxidation of dopamine with drastic decrease in the peak potentials separation and important enhancement in the associated currents. Dopamine was detected by differential pulse voltammetry‐adsorptive stripping with medium exchange at nanomolar levels even in the presence of high excess of ascorbic and uric acids. The sensor was successfully used for the quantification of dopamine in urine samples enriched with the neurotransmitter. 相似文献
85.
Adina Borbély Dr. Eduard Figueras Ana Martins Dr. Lizeth Bodero Dr. André Raposo Moreira Dias Dr. Paula López Rivas Dr. Arianna Pina Dr. Daniela Arosio Dr. Paola Gallinari Dr. Marcel Frese Dr. Christian Steinkühler Prof. Dr. Cesare Gennari Prof. Dr. Umberto Piarulli Prof. Dr. Norbert Sewald 《ChemistryOpen》2019,8(6):737-742
RGD-cryptophycin and isoDGR-cryptophycin conjugates were synthetized by combining peptidomimetic integrin ligands and cryptophycin, a highly potent tubulin-binding antimitotic agent across lysosomally cleavable Val-Ala or uncleavable linkers. The conjugates were able to effectively inhibit binding of biotinylated vitronectin to integrin αvβ3, showing a binding affinity in the same range as that of the free ligands. The antiproliferative activity of the novel conjugates was evaluated on human melanoma cells M21 and M21-L with different expression levels of integrin αvβ3, showing nanomolar potency of all four compounds against both cell lines. Conjugates containing uncleavable linker show reduced activity compared to the corresponding cleavable conjugates, indicating efficient intracellular drug release in the case of cryptophycin-based SMDCs. However, no significant correlation between the in vitro biological activity of the conjugates and the integrin αvβ3 expression level was observed, which is presumably due to a non-integrin-mediated uptake. This reveals the complexity of effective and selective αvβ3 integrin-mediated drug delivery. 相似文献
86.
Beatriz Rivas‐Murias Juan M. Asensio Nicolas Mille Benito Rodríguez‐Gonzlez Pier‐Francesco Fazzini Julian Carrey Bruno Chaudret Vernica Salgueirio 《Angewandte Chemie (International ed. in English)》2020,59(36):15537-15542
Magnetically induced catalysis can be promoted taking advantage of optimal heating properties from the magnetic nanoparticles to be employed. However, when unprotected, these heating agents that are usually air‐sensitive, get sintered under the harsh catalytic conditions. In this context, we present, to the best of our knowledge, the first example of air‐stable magnetic nanoparticles that: 1) show excellent performance as heating agents in the CO2 methanation catalyzed by Ni/SiRAlOx, with CH4 yields above 95 %, and 2) do not sinter under reaction conditions. To attain both characteristics we demonstrate, first the exchange‐coupled magnetic approach as an alternative and effective way to tune the magnetic response and heating efficiency, and second, the chemical stability of cuboctahedron‐shaped core–shell hard CoFe2O4–soft Fe3O4 nanoparticles. 相似文献
87.
Polyelectrolyte (PEL)-based dual systems and nanoparticles (NPs) are two topics which have generated great interest as a result of their many and novel applications. Here, PEL–NPs system which appears transitorily when a high molecular weight PEL solution is mixed with metal NP colloidal dispersions during diafiltration is studied. The aim of this paper was to analyze the concentration–polarization effect of PEL molecules on size distribution of NPs capable to pass through the ultrafiltration membrane. Poly(sodium styrene sulfonate) (PSSNa) and silver nanoparticles (AgNPs) were used as PEL and metal NP colloidal dispersion, respectively. It was seen that particle size decreased from 42.4?±?37.8 to 10.1?±?0.7 nm in the presence of PSSNa and concentration–polarization. In addition, our results indicate that polarization–concentration phenomenon can be used to modify the size distribution of NP colloidal dispersions, that by changes of polarization–concentration features is possible the modification of NP size in the permeate during diafiltration experiments and that in presence of concentration–polarization, PSSNa was only a modifier factor of medium. In addition, it was observed that exclusion size of ultrafiltration membrane is an important element for establishing of particle size in the permeate. 相似文献
88.
89.
S. Blanco-Canosa F. Rivadulla A. Pi?eiro V. Pardo D. Baldomir M.A. López-Quintela J. Rivas 《Journal of magnetism and magnetic materials》2010,322(9-12):1069-1071
We report high-pressure diffraction and magnetization measurements to demonstrate that the partial collapse of electronic gap at high-pressure insulator to metal transition reported in TiOCl (C. Kuntscher et al. Phys. Rev. B 74 184402 (2006).) corresponds to a Ti3+–Ti3+ dimerization at room temperature within the space group P21/m. The shortest Ti–Ti distance is comparable to that of the Ti metal, but a Peierls-like distortion prevents a metallic behaviour. 相似文献
90.
Ana Lucía Campaa Amaimen Guilln Ricardo Rivas Veronica Akle Juan C. Cruz Johann F. Osma 《Molecules (Basel, Switzerland)》2021,26(14)
This study presents the feasibility of using various functionalized substrates, Fe3O4 nanoparticles (NPs) and Al2O3 spheres, for the removal of Cd from aqueous solution. To improve the materials’ affinity to Cd, we explored four different surface modifications, namely (3-Aminopropyl) triethoxysilane (APTES), L-Cysteine (Cys) and 3-(triethoxysilyl) propylsuccinic anhydride (CAS). Particles were characterized by FTIR, FIB-SEM and DLS and studied for their ability to remove metal ions. Modified NPs with APTES proved to be effective for Cd removal with efficiencies of up to 94%, and retention ratios up to 0.49 mg of Cd per g of NPs. Batch adsorption experiments investigated the influence of pH, contact time, and adsorbent dose on Cd adsorption. Additionally, the recyclability of the adsorbent and its potential phytotoxicity and animal toxicity effects were explored. The Langmuir, Freundlich, pseudo-first-order and pseudo-second-order models were applied to describe the behavior of the Cd adsorption processes. The adsorption and desorption results showed that Fe3O4 NPs modified with APTES are promising low-cost platforms with low phytotoxicity for highly efficient heavy metal removal in wastewater. 相似文献