Silver nanoparticle incorporation into flexible polyamide 12 membranes.

To meet the demands of the market and society, the development of structured polymeric materials for application in the medical field is constantly increasing. Over the last decades, metallic silver nanoparticles have been explored due to their antimicrobial action. Here, we aimed to incorporate metallic silver nanoparticles into polymeric pieces obtained by additive manufacture via a chemical route involving silver nitrate and sodium borohydride. Polyamide 12 membranes were obtained by selective laser sintering, which was followed by washing, pretreatment, and functionalization with the alkoxides tetraethylorthosilicate and 3-aminopropyl tetraethoxysilane. For nanoparticle preparation and incorporation, a chemical route was tested under different conditions. The samples were characterized by techniques, such as X-ray diffraction, ultraviolet-visible spectroscopy, and infrared vibrational spectroscopy. Nanoparticle formation and incorporation into the polyamide 12 membranes were demonstrated by the absorbance band at 420 nm, which indicated that the particles measured between 10 and 50 nm in size; by the X-ray diffraction peaks at 2θ = 38, 44, and 64°, which are typical of crystalline silver; and by vibrational spectroscopy, which evidenced that the nanoparticles interacted with the polyamide 12 nitrogen groups. Polyamide 12 membranes containing metallic silver nanoparticles have promising biomedical applications as antimicrobial wound dressings associated with drug carriers.

Non-hydrolytic Sol-Gel Route: a Powerful Process to Develop UV-Vis-IR Luminescent YVO4 Phosphors.

The spectroscopic properties of lanthanide ions stem from absorption and emission radiation in the solar spectrum range, which promotes numerous applications in areas such as white light emission, bio-imaging, biological markers, and photovoltaic cells, among others. To intensify these properties, several matrixes have been studied, particularly the yttrium vanadate matrix due to its structural, mechanic, and physicochemical properties. The non-hydrolytic sol-gel process is a versatile way to prepare inorganic oxides doped with lanthanide ions. In this work, we describe the synthesis of yttrium vanadate matrixes doped with Eu3+, Er3+, and/or Yb3+ ions (containing 1% lanthanide ions with respect to Y3+ (molar ratio)) by the non-hydrolytic sol-gel, annealed at 800 °C for 4 h, and their characterization by X-ray diffraction and photoluminescence spectroscopy. The X-ray diffraction patterns display the peaks corresponding to the yttrium vanadate tetragonal phase. Laser excitation at 980 nm elicits Er3+ emission bands in the green and red regions and Eu3+ emission at 620 nm. Laser excitation at 322 nm; i.e., the charge transfer band, provides emission in the same regions, as well as infrared emission. This system is a promising candidate for applications in solar cells, optical amplifiers, and biomarkers because it can be excited at different wavelengths. Graphical Abstract Schematic diagram of the energy level of lanthanides and vanadate ions, and energy transfer.

Synthesis, Characterization, and Environmental Applications of Hybrid Materials Based on Humic Acid Obtained by the Sol-Gel Route.

Humic acids (HAs) are ubiquitous macromolecules in the environment. Due to their high contents of oxygenated functional groups, they can interact with contaminants present in the natural environment and therefore influence the behavior of pollutants. However, a pH of 2 or lower is required to maintain HAs in the solid form. To increase the stability of HAs and their capacity to bind to contaminants, this work proposes the development of new hybrid materials based on alkoxysilanes and HAs for environmental applications such as dye adsorption. Three different materials with new functional groups were prepared by employing the following alkoxysilanes: tetraethyl orthosilicate, (3-aminopropyl)triethoxysilane, and N-[3-(trimethoxylsilyl)propyl]ethylenediamine. The final materials were denoted HWA, HOA, and HTA, respectively, and they were characterized by elemental analysis, diffuse reflectance Fourier-transform infrared spectroscopy (DRIFT), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and N2 gas-volumetric adsorption. The point of zero charge (pzc) and stability of these materials were also determined. Their selectivity was evaluated in adsorption experiments performed with two different charged dyes in aqueous medium, namely anionic rose bengal (RB) and cationic methylene blue (MB). The elemental, DRIFT, SAXS, SEM, and textural analyses confirmed the presence of a combination of the features of HAs and alkoxysilanes. The pzc results showed that the new materials displayed different characteristics and affinities. All the materials were stable in aqueous solution up to pH 10. For MB, the percentage removal values obtained by using HWA, HOA, and HTA were 98, 85, and 67%, respectively. As for RB, the percentage removal values were 19, 18, and 44% for HWA, HOA, and HTA, respectively. These hybrid materials have potential use as adsorbents for the removal of cationic or anionic species and could be viable alternatives to remove various substances present as contaminants in natural environments.