Optical Modification of a Nanoporous Alumina Structure Associated with Surface Coverage by the Ionic Liquid AliquatCl.

This manuscript analyses changes in the optical parameters of a commercial alumina nanoporous structure (AnodiscTM or AND support) due to surface coverage by the ionic liquid (IL) AliquatCl (AlqCl). XPS measurements were performed for chemical characterization of the composite AND/AlqCl and the AND support, but XPS resolved angle analysis (from 15° to 75°) was carried out for the homogeneity estimation of the top surface of the ANDAlqCl sample. Optical characterization of both the composite AND/AlqCl and the AND support was performed by three non-destructive and non-invasive techniques: ellipsometry spectroscopy (SE), light transmittance/reflection, and photoluminescence. SE measurements (wavelength ranging from 250 nm to 1250 nm) allow for the determination of the refraction index of the AND/AlqCl sample, which hardly differs from that corresponding to the IL, confirming the XPS results. The presence of the IL significantly increases the light transmission of the alumina support in the visible region and reduces reflection, affecting also the maximum position of this latter curve, as well as the photoluminescence spectra. Due to these results, illuminated I-V curves for both the composite AND/AlqCl film and the AND support were also measured to estimate its possible application as a solar cell. The optical behaviour exhibited by the AND/AlqCl thin film in the visible region could be of interest for different applications.

Optical and Electrochemical Properties of a Nanostructured ZnO Thin Layer Deposited on a Nanoporous Alumina Structure via Atomic Layer Deposition.

This study explores the optical and electrochemical properties of a ZnO coating layer deposited on a nanoporous alumina structure (NPAS) for potential multifunctional applications. The NPAS, synthesized through an electrochemical anodization process, displays well-defined nanochannels with a high aspect ratio (~3000). The ZnO coating, achieved via atomic layer deposition, enables the tuning of the pore diameter and porosity of the NPAS, thereby influencing both the optical and electrochemical interfacial properties. A comprehensive characterization using photoluminescence, spectroscopy ellipsometry and impedance spectroscopy (with the sample in contact with NaCl solutions) provides insights into optical and electrochemical parameters, including the refractive index, absorption coefficient, and electrolyte-ZnO/NPAS interface processes. This research demonstrates potential for tailoring the optical and interfacial properties of nanoporous structures by selecting appropriate coating materials, thus opening avenues for their utilization in various technological applications.

Modification of the Physical Properties of a Nafion Film Due to Inclusion of n-Dodecyltriethylammonium Cation: Time Effect.

This study investigates the effects of modifying commercial Nafion-212 thin films with dodecyltriethylammonium cation (DTA+) on their electrical resistance, elastic modulus, light transmission/reflection and photoluminescence properties. The films were modified through a proton/cation exchange process for immersion periods ranging from 1 to 40 h. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to analyze the crystal structure and surface composition of the modified films. The electrical resistance and the different resistive contributions were determined via impedance spectroscopy. Changes in the elastic modulus were evaluated using stress-strain curves. Additionally, optical characterization tests, including light/reflection (250-2000 nm) and photoluminescence spectra, were also performed on both unmodified and DTA+-modified Nafion films. The results reveal significant changes in the electrical, mechanical and optical properties of the films, depending on the exchange process time. In particular, the inclusion of the DTA+ into the Nafion structure improved the elastic behavior of the films by significantly decreasing the Young modulus. Furthermore, the photoluminescence of the Nafion films was also enhanced. These findings can be used to optimize the exchange process time to achieve specific desired properties.

Effects of Tepary bean (Phaseolus acutifolius) protease inhibitor and semipure lectin fractions on cancer cells.

Some natural and synthetic protease inhibitors (PI), such as the Bowman-Birk PI from soybean, have anticancer effects. We previously purified and characterized a Bowman-Birk-type PI from Tepary bean (Phaseolus acutifolius) seeds (TBPI). A semipure protein fraction containing this inhibitor, when tested its in vitro effect on transformed cells, showed a differential cytotoxic effect, as well as an increase in cell attachment to culture dishes. In this article we report that lectins were responsible for the cytotoxic effect previously observed, exhibiting a differential, antiproliferative effect on nontransformed cells and on different lineages of cancer cells. Although the purified TBPI lacked cytotoxicity, it was found to be responsible for the increase in cell adhesion, decreasing culture dishes' extracellular matrix degradation, leading to a decrease of the in vitro cell invasion capacity. This effect coincided with the suppression of Matrix Metalloproteinase-9 activity. These results indicate that Tepary bean seeds contain at least 2 different groups of bioactive proteins with distinct effects on cancer cells.

Nanoporous Alumina Support Covered by Imidazole Moiety-Based Ionic Liquids: Optical Characterization and Application.

This work analyzes chemical surface and optical characteristics of a commercial nanoporous alumina structure (NPAS) as a result of surface coverage by different imidazolium-based ionic liquids (1-butyl-3-metylimidazolium hexafluorophosphate, 3-methyl-1-octylimidazolium hexafluorophosphate, or 1-ethyl-3-methylimidazolium tetrafluoroborate). Optical characteristics of the IL/NPAS samples were determined by photoluminescence (at different excitation wavelengths (from 300 nm to 400 nm), ellipsometry spectroscopy, and light transmittance/reflectance measurements for a range of wavelengths that provide information on modifications related to both visible and near-infrared regions. Chemical surface characterization of the three IL/NPAS samples was performed by X-ray photoelectron spectroscopy (XPS), which indicates almost total support coverage by the ILs. The IL/NPAS analyzed samples exhibit different photoluminescence behavior, high transparency (<85%), and a reflection maximum at wavelength ~380 nm, with slight differences depending on the IL, while the refractive index values are rather similar to those shown by the ILs. Moreover, the illuminated I−V curves (under standard conditions) of the IL/NPAS samples were also measured for determining the efficiency energy conversion to estimate their possible application as solar cells. On the other hand, a computational quantum mechanical modeling method (DFT) was used to establish the most stable bond between the ILs and the NPAS support.

Optical and Physicochemical Characterizations of a Cellulosic/CdSe-QDs@S-DAB5 Film.

CdSe quantum dots nanoparticles were coated with the thiolated (DiAminoButane based dendrimer) DAB dendrimer of fifth generation (S-DAB5) and embedded in a highly hydrophilic regenerated cellulose (RC) film by simple dip-coating method (immersion in QD-dendrimer aqueous solution) as a way to get a flexible nano-engineered film (RC-4/CdSe-QDs@S-DAB5) with high transparency and photoluminescence properties for different applications. Optical changes in the RC film associated with QDs inclusion were determined by spectroscopic ellipsometry (SE) measurements, which provide information on changes caused in the refraction index and the extinction coefficients of the film, as well as by light transmittance/reflectance curves and photoluminescence (PL) spectra. Impedance spectroscopy (IS) and other typical physicochemical techniques for material characterization (TEM, SEM and XPS) have also been used in order to have more complete information on film characteristics. A comparison of RC-4/CdSe-QDs@S-DAB5 film optical characteristics with those exhibited by other RC-modified films depending on the type of dendrimer was also carried out.

Insights into the formation of an emissive CdTe-quantum-dots/cellulose hybrid film.

Optical and electrical modifications of a highly hydrophilic cellulose regenerated (RC) thin film as result of the inclusion in the film structure of cadmium-tellurium covered with mercaptosuccinic acid quantum dot nanoparticles (CdTe-MSA QDs) are analysed. CdTe-MSA QDs nanoparticles inclusion was performed by dip-coating of the RC film in an aqueous nano QDs solution, and two different immersion periods (2 h and 24 h) were considered. Impedance spectroscopy measurements, which can give information of changes in both film surface and bulk phase were performed for CdTe-MSA QDs inclusion confirmation as well as the estimation of electrical changes associated to QDs modification. Optical characterization of the original support and the CdTe-MSA(2 h) and CdTe-MSA(24 h) modified films was carried out by light transmittance and ellipsometry spectroscopy (at three different take-off angles). According to these results, the inclusion of CdTe-MSA QDs practically does not reduce the high transparency of the film support, but it increases the reflexion index and extinction coefficient of both modified films. Moreover, fluorescence and XPS measurements were also performed for more complete information on the effect caused by the presence of CdTe-MSA QDs in the cellulosic film. A comparison of changes in physicochemical properties of the cellulosic/CdTe-MSA QDs films and those modified with other nanoparticle quantum dots is also performed.