Caffeine photocatalytic degradation using composites of NiO/TiO2–F and CuO/TiO2–F under UV irradiation

The interest in the removal of emerging contaminants has increased in the last decade. Photocatalytic degradation using p-n heterojunctions could effectively provide the degradation of these type of substances that are persistent in the environment. In this work, the synthesis, characterization, and photocatalytic evaluation of TiO2–F as well as CuO/TiO2–F and NiO/TiO2–F composite materials were studied in the photo-assisted degradation of caffeine using UV radiation. The fluorination of titanium dioxide induced changes in some physicochemical properties of the materials, which contributed to a decrease in surface area and bandgap energy as well as an increase in crystallite size as compared to pristine TiO2. ≡Ti–F species were evidenced to be formed, which could favor charge separation processes. A highest segregation of CuO species in comparison with NiO on the surface of TiO2–F could be formed, which could increase defect sites and decrease the band gap. The formation of a heterojunction between the semiconductors was evidenced, responsible for the observed improvements in photocatalytic properties of the composite materials. The photocatalytic tests evidenced an important degradation of caffeine; however, mineralization was incomplete. The stability of the composite materials and their potential use in the photocatalytic treatment of caffeine was evaluated by reuse tests

Carbon Nitrogen, and Oxygen Galactic Gradients: A Solution to the Carbon Enrichment Problem

Eleven models of Galactic chemical evolution, differing in the carbon, nitrogen,and oxygen yields adopted, have been computed to reproduce the Galactic O/H values obtained from H II regions. All the models fit the oxygen gradient, but only two models fit also the carbon gradient, those based on carbon yields that increase with metallicity due to stellar winds in massive stars (MS) and decrease with metallicity due to stellar winds in low and intermediate mass stars (LIMS). The successful models also fit the C/O versus O/H evolution history of the solar vicinity obtained from stellar observations. We also compare the present day N/H gradient and the N/O versus O/H and the C/Fe, N/Fe, O/Fe versus Fe/H evolution histories of the solar vicinity predicted by our two best models with those derived from H II regions and from stellar observations. While our two best models fit the C/H and O/H gradients as well as the C/O versus O/H history, only Model 1 fits well the N/H gradient and the N/O values for metal poor stars but fails to fit the N/H values for metal rich stars. Therefore we conclude that our two best models solve the C enrichment problem, but that further work needs to be done on the N enrichment problem. By adding the C and O production since the Sun was formed predicted by Models 1 and 2 to the observed solar values we find an excellent agreement with the O/H and C/H values of the solar vicinity derived from H II regions O and C recombination lines. One of the most important results of this paper is that the fraction of carbon due to MS and LIMS in the interstellar medium is strongly dependent on time and on the galactocentric distance; at present about half of the carbon in the interstellar medium of the solar vicinity has been produced by MS and half by LIMS.Comment: 34 pages, 6 tables, 7 figures. Accepted for publication in Ap

Acetylated nanocellulose for single-component bioinks and cell proliferation on 3D-printed scaffolds

Nanocellulose has been demonstrated as a suitable material for cell culturing, given its similarity to extracellular matrices. Taking advantage of the shear thinning behavior, nanocellulose suits three-dimensional (3D) printing into scaffolds that support cell attachment and proliferation. Here, we propose aqueous suspensions of acetylated nanocellulose of a low degree of substitution for direct ink writing (DM). This benefits from the heterogeneous acetylation of precursor cellulosic fibers, which eases their deconstruction and confers the characteristics required for extrusion in DIW. Accordingly, the morphology of related 3D printed architectures and their performance during drying and rewetting as well as interactions with living cells are compared with those produced from typical unmodified and TEMPO-oxidized nanocelluloses. We find that a significantly lower concentration of acetylated nanofibrils is needed to obtain bioinks of similar performance, affording more porous structures. Together with their high surface charge and axial aspect, acetylated nanocellulose produces dimensionally stable monolithic scaffolds that support drying and rewetting, required for packaging and sterilization. Considering their potential uses in cardiac devices, we discuss the interactions of the scaffolds with cardiac myoblast cells. Attachment, proliferation, and viability for 21 days are demonstrated. Overall, the performance of acetylated nanocellulose bioinks opens the possibility for reliable and scaleup fabrication of scaffolds appropriate for studies on cellular processes and for tissue engineering.Peer reviewe

Cellulose acetate films from chemo-enzymatic dissolving pulps

The purpose of this work is to obtain dissolving cellulose fibers that are suitable for the manufacturing of cellulose derivatives. Therefore, the combination of enzymatic and chemical treatments during the bleaching stage (lignin removal) and purification stage (hemicellulose removal) is proposed. The obtained dissolving cellulose was submitted to acetylation reactions, and then acetate films were prepared as an example of end product. Assessing the quality of acetate films, it was concluded that dissolving cellulose fibers had good properties and fulfilled the quality requirements. These satisfactory results were compared with acetate films obtained under same acetylation conditions, but the dissolving cellulose fibers used as a raw material came from a conventional and industrial process.This publication is part of the PID2020-114070RB-I00 (CELLECOPROD) project, funded by MCIN/AEI/10.13039/501100011033. O.J.R. acknowledges funding support by the Academy of Finland through its Center of Excellence Program (2014–2019) “Molecular Engineering of Biosynthetic Hybrid Materials Research”.Peer ReviewedPostprint (published version

Microfibers synthesized by wet-spinning of chitin nanomaterials : mechanical, structural and cell proliferation properties

Partially deacetylated chitin nanofibers (ChNF) were isolated from shell residues derived from crab biomass and used to prepare hydrogels, which were easily transformed into continuous microfibers by wet-spinning. We investigated the effect of ChNF solid content, extrusion rate and coagulant type, which included organic (acetone) and alkaline (NaOH and ammonia) solutions, on wet spinning. The properties of the microfibers and associated phenomena were assessed by tensile strength, quartz crystal microgravimetry, dynamic vapor sorption (DVS), thermogravimetric analysis and wide-angle X-ray scattering (WAXS). The as-spun microfibers (14 GPa stiffness) comprised hierarchical structures with fibrils aligned in the lateral direction. The microfibers exhibited a remarkable water sorption capacity (up to 22 g g−1), while being stable in the wet state (50% of dry strength), which warrants consideration as biobased absorbent systems. In addition, according to cell proliferation and viability of rat cardiac myoblast H9c2 and mouse bone osteoblast K7M2, the wet-spun ChNF microfibers showed excellent results and can be considered as fully safe for biomedical uses, such as in sutures, wound healing patches and cell culturing.Peer reviewe

Fabrication and Characterization of Drug-Loaded Conductive Poly(glycerol sebacate)/Nanoparticle-Based Composite Patch for Myocardial Infarction Applications

Heart tissue engineering is critical in the treatment of myocardial infarction, which may benefit from drug-releasing smart materials. In this study, we load a small molecule (3i-1000) in new biodegradable and conductive patches for application in infarcted myocardium. The composite patches consist of a biocompatible elastomer, poly(glycerol sebacate) (PGS), coupled with collagen type I, used to promote cell attachment. In addition, polypyrrole is incorporated because of its electrical conductivity and to induce cell signaling. Results from the in vitro experiments indicate a high density of cardiac myoblast cells attached on the patches, which stay viable for at least 1 month. The degradation of the patches does not show any cytotoxic effect, while 3i-1000 delivery induces cell proliferation. Conductive patches show high blood wettability and drug release, correlating with the rate of degradation of the PGS matrix. Together with the electrical conductivity and elongation characteristics, the developed biomaterial fits the mechanical, conductive, and biological demands required for cardiac treatment.Peer reviewe

Multifunctional 3D-printed patches for long-term drug release therapies after myocardial infarction

A biomaterial system incorporating nanocellulose, poly(glycerol sebacate), and polypyrrole is introduced for the treatment of myocardial infarction. Direct ink writing of the multicomponent aqueous suspensions allows multifunctional lattice structures that not only feature elasticity and electrical conductivity but enable cell growth. They are proposed as cardiac patches given their biocompatibility with H9c2 cardiomyoblasts, which attach extensively at the microstructural level, and induce their proliferation for 28 days. Two model drugs (3i‐1000 and curcumin) are investigated for their integration in the patches, either by loading in the precursor suspension used for extrusion or by direct impregnation of the as‐obtained, dry lattice. In studies of drug release conducted for five months, a slow in vitro degradation of the cardiac patches is observed, which prevents drug burst release and indicates their suitability for long‐term therapy. The combination of biocompatibility, biodegradability, mechanical strength, flexibility, and electrical conductivity fulfills the requirement of the highly dynamic and functional electroresponsive cardiac tissue. Overall, the proposed cardiac patches are viable alternatives for the regeneration of myocardium after infarction through the effective integration of cardiac cells with the biomaterial.Peer reviewe

Generation of Tamm Plasmon Resonances for Light Confinement Applications in Narrowband Gradient-Index Filters Based on Nanoporous Anodic Alumina

Gold-coated gradient-index filters based on nanoporous anodic alumina (Au-coated NAA−GIFs) were used as model platforms to elucidate how Tamm plasmons can be tailored by engineering the geometric features of the plasmonic and photonic components of these hybrid structures. NAA−GIFs with well-resolved, intense photonic stopbands at two positions of the visible spectrum were fabricated through sinusoidal pulse anodization. These model photonic crystals were used to assess how the quality of Tamm plasmon resonances can be enhanced by tuning the features of the dielectric mirror and the thickness of the porous gold coating layer. It is found that the highest value of the quality factor of Tamm resonance (QTamm = 237) is obtained for 11 nm of gold on a dielectric mirror with low porosity corresponding to the resonant spectral position of λTamm of ∼698 nm. Our analysis indicates that Tamm resonances in asproduced Au-coated NAA−GIFs are weak due to the constrained range of wavelengths (narrow bands) at which these photonic crystal structures reflect light. However, after broadening of their photonic stopband upon pore widening, Tamm resonances become better resolved, with higher intensity. It is also observed that the quality of light confinement worsens progressively with the thickness of the porous gold coating layer after a critical value. In contrast to conventional surface plasmon resonance systems, this hybrid Tamm porous system does not require complex coupling systems and provides a nanoporous structure that can be readily tailored for a range of photonic technologies such as sensing and lasing.Alejandro Rojas Gómez, Laura K. Acosta, Josep Ferré-Borrull, Abel Santos, and Lluis F. Marsa