National Institute Of Materials Physics - Romania

Background: Alzheimer's disease has a significant epidemiological and socioeconomic impact, and, unfortunately, the extensive research focused on potential curative therapies has not yet proven to be successful. However, in recent years, important steps have been made in the development and functionalization of nanoporous alumina membranes, which might be of great interest for medical use, including the treatment of neurodegenerative diseases. In this context, the aim of this article is to present the synthesis and biocompatibility testing of a special filtrating nano-membrane, which is planned to be used in an experimental device for Alzheimer's disease treatment. Methods: Firstly, the alumina nanoporous membrane was synthesized via the two-step anodizing process in oxalic acid-based electrolytes and functionalized via the atomic layer deposition technique. Subsequently, quality control tests (spectrophotometry and potential measurements), toxicity, and biocompatibility tests (cell viability assays) were conducted. Results: The proposed alumina nanoporous membrane proved to be efficient for amyloid-beta filtration according to the permeability studies conducted for 72 h. The proposed membrane has proven to be fully compatible with the tested cell cultures. Conclusions: The proposed alumina nanoporous membrane model is safe and could be incorporated into implantable devices for further in vivo experiments and might be an efficient therapeutic approach for Alzheimer's disease.

The effectiveness of the electrochemical WO3-modification as a method for improving the photoactivity of native air-formed TiO2 layers was assessed. The way in which a mild laser treatment influences the photo-electrochemical performances of the thus obtained WO3/TiO2 systems was also investigated. At laser-treated electrodes (L-WO3/TiO2), the melting-solidification process induced by the treatment led to a smaller size of the deposited WO3 particles and to their better dispersion on the surface. The treatment also enhanced the surface oxygen deficiency and ensured better relative absorptivity of the oxygenated species on the surface. These features, together with the intrinsic narrower bandgap of the WO3/TiO2 composites, the higher donor density and the lower flat band potential of L-WO3/TiO2 enabled faster kinetic of the oxygen photoanodic evolution. Importantly, the same process exhibited a cathodic shift of its onset potential. The laser treatment also strongly enhanced the photoelectrocatalytic performances for UV-assisted methanol anodic oxidation.

The remarkable properties of Eu2+-activated phosphors, related to the broad and intense luminescence of Eu2+ ions, showed a high potential for a wide range of optical-related applications. Oxy-fluoride glass-ceramic containing Europium (II)-doped CaF2 nanocrystals embedded in silica matrix were produced in two steps: glass-ceramization in air at 800 degrees with Eu3+-doped CaF2 nanocrystals embedded followed by Eu3+ to Eu2+ reduction during annealing in reducing atmosphere. The broad, blue luminescence band at 425 nm and with the long, weak tail in the visible range is assigned to the d -> f type transition of the Eu2+ located inside the CaF2 nanocrystals in substitutional and perturbed sites, respectively; the photoluminescence quantum yield was about 0.76. The X-ray photoelectron spectroscopy and Electron paramagnetic spectroscopy confirmed the presence of Eu2+ inside the CaF2 nanocrystals. Thermoluminescence curves recorded after X-ray irradiation of un-doped and Eu2+-doped glass-ceramics showed a single dominant glow peak at 85 degrees C related to the recombination between F centers and Eu2+ related hole within the CaF2 nanocrystals. The applicability of the procedure can be tested to obtain an oxy-fluoride glass-ceramic doped with other divalent ions such as Sm2+, Yb2+, as nanophosphors for radiation detector or photonics-related applications.

Monocrystalline (100) semi-insulating gallium arsenide (GaAs) samples were irradiated with a 250-keV Xe+ ion beam at room temperature. To investigate the effect of ion irradiation on GaAs samples, the ion fluence was varied from 1 x 1012 to 3 x 1016 ions/cm2. The spectroscopic ellipsometry (SE) method and the Rutherford backscattering spectrometry (RBS) with nuclear reaction (NR) method were used to determine the properties of the virgin and implanted samples. The SE approach reveals that the pseudo-dielectric function of implanted GaAs samples varies with ion fluence. The RBS approach, which exposes the depth-profile of As, Ga, and Xe in the implanted samples, allows us to correlate changes in the pseudo-dielectric function with structural modifications caused by the ion irradiation. The NR approach points out the existence of an oxygen-enriched layer on the surface of implanted GaAs samples. Lastly, the optical study involving the Cauchy and Urbach dispersion model measures the refractive index n and extinction coefficient k of the native oxide layer on the surface of GaAs samples.

This paper presents the results concerning monotropic nematic liquid crystals 4-pentylphenyl 40-alkyl benzoate (5PnB) (n = 3 or 5 carbon atoms in the alkyl chain). Their mesophase properties were supported by images of the polarized optical microscopy. Molecular dynamics in the bulk samples or in the composites prepared with aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range, appropriately chosen. Thermo gravimetric and infrared investigations were additionally performed. The data were compared with those of structurally related nematics like cyanophenyl pentyl benzoates, which have a cyan group instead of the pentyl chain. The dielectric spectra of the bulk 3P5B and 5P5B demonstrate a dielectric behavior with several relaxation processes as expected for nematic liquid crystals. The temperature dependence of the relaxation rates (and of the dielectric strength) seems to have two distinguished regimes. Thus, in the isotropic state, at higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is fitted at lower temperature, in a close similarity to the behavior of a constrained dynamic glass transition. Samples with a high density of silica (larger than 7 g aerosil/1 g of 5PnB) were prepared to observe a thin layer adsorbed on the particle surface; it was estimated that almost each guest 5PnB molecule interacts with the aerosil surface. For the composites only one main relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in the surface layer. Infrared spectroscopy shows that these molecules interact with the surface by the ester carbonyl group leading to the monolayer self-assembly at liquid-solid interface. We note once more the importance of the functional unit(s) for the interaction with the hydroxyl groups on the aerosil surface. (c) 2022 Elsevier B.V. All rights reserved.

Melanoma is a skin cancer characterized by rapid growth and spread for which current therapies produce both resistance and increased risk of infection. To develop new anti-melanoma biocompatible species, the series of complexes Cu(N-N)(bzac)(X)center dot nH(2)O (N-N: 1,10-phenanthroline/2,2 '-bipyridine, Hbzac: 1-phenyl-1,3-butanedione, X: NO3/ClO4, and n = 0, 1) was studied. Single-crystal X-ray diffraction revealed a mononuclear structure for all complexes. The ability of the complexes to scavenge or trap reactive oxygen species such as O-2 center dot(-) and HO center dot was proved by EPR spectroscopy experiments. All complexes inhibited B16 murine melanoma cells in a dose-dependent and nanomolar range, but the complexes with 1,10-phenanthroline were more active. Moreover, comparative activity on B16 and healthy BJ cells revealed a therapeutic index of 1.27-2.24. Bioinformatic methods were used to calculate the drug-likeness, pharmacokinetic, pharmacogenomic, and pharmacodynamic profiles of the compounds. The results showed that all compounds exhibit drug-likeness features, as well as promising absorption, distribution, metabolism, and excretion (ADME) properties, and no toxicity. The pharmacodynamics results showed that the neutral species appear to be good candidates for antitumor molecular targets (Tyrosyl-DNA phosphodiesterase 1, DNA-(apurinic or apyrimidinic site) lyase or Kruppel-like factor 5). Furthermore, the pharmacogenomic results showed a good affinity of the copper(II) complexes for the human cytochrome. These results recommend complexes bearing 1,10-phenanthroline as good candidates for developing drugs to melanoma alternative treatment.

Herein, the properties of the organic heterostructures with triple-layer ZnO/Ag/ZnO as a replacement for ITO and mixed layer containing arylenevinylene oligomer (based on triphenylamine or carbazole) donor and nonfullerene (perylene diimide) acceptor mixed in the ratio 1:2 and the effect of a buffer layer of PEDOT-PSS intercalated between triple layer and mixed organic layer are discussed. The UV-vis transmission and photoluminescence (PL) properties are investigated in correlation with the surface topography and reveal a good match between the absorption and emission domain, which can favor the generation of the charge carriers. The heterostructure with the mixed layer based on triphenylamine oligomer shows the widest absorption domain, and the PL spectra of the heterostructures realized with either triphenylamine or carbazole oligomer show peaks corresponding to the radiative decay of the donor and acceptor. The I-V characteristics in the dark indicate a slightly nonlinear behavior and the current is affected by the charge carriers recombination on the defects present in the thick mixed layer deposited by matrix-assisted pulsed laser evaporation. The effect of the PEDOT-PSS buffer layer on the electrical properties of the organic heterostructure with ZnO/Ag/ZnO electrode is also investigated.

This study addresses the deposition with improved adhesion of TiO2:N/SiO(2)mixture, with different concentrations of the nano-powders (NPs) (1:0,5; 1:1 and 1:1,5) on 100% cotton fabrics. The characteristics of the deposited thin films were investigated by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), Raman scattering, FTIR, and UV-VIS absorption spectroscopy. To improve the treatment durability to the external factors, the different crosslinking methods were used. Photocatalytic activity of functionalized textile fabrics was evaluated by determining the photodegradation efficiency of the methylene blue (MB) dye and forest juice, measuring the color difference of the irradiated samples compared with non-irradiated samples. Washing durability of the samples was achieved qualitatively by determining the photocatalytic activity remaining on the textile fabrics after 1 and 5 washing cycles. The samples treated with the mixture of TiO2:N/SiO(2)have demonstrated improved self-cleaning properties, the highest photocatalytic activity being obtained for the highest value of TiO2:N/SiO(2)NPs molar concentrations equal to 1:1.