Publicaciones 2011-2020

@article{RN318,
title = {Fluorescence and Surface-Enhanced Vibrational Spectroscopies of Lawsone and Plumbagin},
author = { A.E. Aliaga and P. Leyton and E. Clavijo and M. Campos-Vallette},
url = {/brokenurl#<Go to ISI>://WOS:000405754400002},
doi = {10.1080/00387010.2016.1146772},
issn = {0038-7010},
year = {2016},
date = {2016-01-01},
journal = {Spectroscopy Letters},
volume = {49},
number = {5},
pages = {326-335},
abstract = {The natural dyes lawsone and plumbagin (1,4-naphthoquinones) were studied by using fluorescence, Raman, infrared (IR), surface-enhanced Raman scattering (SERS), and surface-enhanced IR absorption. From the absorption spectrum, it was possible to infer that the enol-lawsone tautomer concentration decreases in silver colloidal solution. Plumbagin dimers, both in water and in silver colloidal solution, were identified from the fluorescence band profile and surface-SERS spectrum. The SERS spectrum of lawsone was obtained by using silver colloidal solution after 12-hour settle; the keto and enol lawsone silver colloid interaction occurs. The assignment of Raman and IR bands of both dyes was calculated with density functional theory calculations. Only a monomeric structure of lawsone interacting with a silver cluster model was predicted. The monomer adopts a nearly coplanar orientation onto the silver surface; the shortest distance is 3.2 angstrom, suggesting an electrostatic interaction.},
keywords = {behavior, calculations, enhanced fluorescence, infrared-absorption, lawsone, nanoparticles, plumbagin, quinones raman raman-scattering, reduction, scattering, selection, sers, silver spectrum, surface theoretical},
pubstate = {published},
tppubtype = {article}
}

@article{RN129,
title = {Experimental and Theoretical Study on the Oxidation Mechanism of Dopamine in N-Octyl Pyridinium Based Ionic Liquids-Carbon Paste Modified Electrodes},
author = { C. Diaz and C. Garcia and P. Iturriaga-Vasquez and M.J. Aguirre and J.P. Muena and R. Contreras and R. Ormazabal-Toledo and M. Isaacs},
url = {/brokenurl#<Go to ISI>://WOS:000329531100111},
doi = {10.1016/j.electacta.2013.08.103},
issn = {0013-4686},
year = {2013},
date = {2013-01-01},
journal = {Electrochimica Acta},
volume = {111},
pages = {846-854},
publisher = {2013 Elsevier Ltd.},
abstract = {This work describes the influence of n-octyl pyridinium cations based ionicliquids-carbon paste modified electrodes on the oxidation mechanism of dopamine. Ionic liquids formed by hexafluorophosphate anion and n-octyl pyridinium [R-OPy](+); R= CH3, H, CF3, where ionic liquids containing CH3 and CF3 are new products, were synthesized and characterized. Modified carbon paste electrodes with these salts were characterized by electrochemicalimpedance spectroscopy and cyclic voltammetry. Electrochemical oxidation of dopamine was studied in PBS buffer solution at pH = 7.4. The influence of the ionic liquids in the oxidation of dopamine was studied by cyclic voltammetry and rotating disk electrode. The results show that typical carbon paste electrode presents an electrochemical/chemical mechanism; whereas [OPy]PF6 and [CF3-OPy]PF6 modified electrodes present an electrochemical/chemical/electrochemical mechanism. The experimental study is complemented with a theoretical analysis of substituent effects in terms of the molecular electrostatic potential, Mulliken population analysis and second order perturbation theory probed at the cation moiety of the IL These indices consistently show an electron density accumulation at the ipso position of the pyridinium moiety of the IL that is in agreement with the electrochemical characterization.},
keywords = {behavior, detection, disk dopamine electrochemical electrode, electrodes, impedance impedance, insights, ionic liquids-carbon mechanism, metabolites, oxidation paste rat rotating separation, spectroscopy, striatum},
pubstate = {published},
tppubtype = {article}
}

@article{RN92,
title = {Structural Aspects of Polyanion and Hydrophobically Modified Polycation Multilayers on Hydrophilic or Hydrophobic Surfaces},
author = { J. Amim and F.C.B. Maia and P.B. Miranda and M. Urz\'{u}a and D.F.S. Petri},
url = {/brokenurl#<Go to ISI>://WOS:000304665400008},
doi = {10.1039/c2sm25658d},
issn = {1744-683x},
year = {2012},
date = {2012-01-01},
journal = {Soft Matter},
volume = {8},
number = {24},
pages = {6462-6470},
abstract = {Multilayer films of carboxymethylcellulose (CMC), a polyanion, and bromide salts of poly(4-vinylpyridine) quaternized with linear aliphatic chains of 2 (ethyl) and 5 (pentyl) carbon atoms, coded as QPVP-C2 and QPVP-C5, respectively, were fabricated by layer-by-layer (LbL) self-assembly onto Si/SiO2 wafers (hydrophilic substrate) or polystyrene, PS, films (hydrophobic substrate). The films were characterized by means of ex situ and in situ ellipsometry, atomic force microscopy (AFM), contact angle measurements and sum frequency generation vibrational spectroscopy (SFG). Antimicrobial tests were used to assess the exposure of pyridinium moieties to the aqueous medium. In situ ellipsometry indicated that for Si/SiO2 the chains were more expanded than the PS films and both substrates systems composed of QPVP-C5 were thicker than those with QPVP-C2. For dried layers, the alkyl side group size had a small effect on the thickness evolution, regardless of the substrate. At pH 2 the multilayers showed high resistance, evidencing that the build-up is driven not only by cooperative polymer-polymer ion pairing, but also by hydrophobic interactions between the alkyl side chains. The LbL films became irregular as the number of depositions increased. After the last deposition, the wettability of QPVP-C2 or QPVP-C5 terminated systems on the Si/SiO2 wafers and PS films were similar, except for QPVP-C2 on Si/SiO2 wafers. Unlike the morphology observed for LbL films on Si/SiO2 wafers, PS induced the formation of porous structures. SFG showed that in air the molecular orientation of pyridinium groups in multilayers with QPVP-C5 was stronger than in those containing QPVP-C2. The exposure of pyridinium moieties to the aqueous medium was more pronounced when the LbL were assembled on Si/SiO2 wafers.},
keywords = {behavior, buildup, by-layer deposition, films, multilayers, polyelectrolyte surfaces, terminated virus},
pubstate = {published},
tppubtype = {article}
}