Allantoin‑zinc layered simple hydroxide biohybrid as antimicrobial active phase in cellulosic bionanocomposites as potential wound dressings

15 Pág.Cellulosic materials loaded with a novel zinc layered simple hydroxide (LSH) with allantoin in its structure (allant-ZnLSH) have been developed for potential application as wound dressings. The allant-ZnLSH biohybrid was synthesized by slow addition of a zinc chloride solution to an aqueous solution of allantoin, while adding a NaOH solution dropwise to maintain a controlled pH. The recovered precipitate was characterized by XRD, FTIR, chemical analysis, and FE-SEM. The allant-ZnLSH material was further incorporated into biopolymeric matrices such as hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC) and cellulose nanofibers (CNF), because of their biocompatibility and biodegradability. The resulting films presented suitable mechanical properties, with Young's modulus values ranging between 1.3 and 3.9 GPa, as well as appropriate water vapor transmission rates (WVTR) for application in would healing, around 250–630 g/m2 per day. The bionanocomposite films also showed interesting barrier properties against the passage of UV light, while keeping a certain transparency in the visible range that would allow the healing process to be monitored without removing the dressing. Their antibacterial action was evaluated against E. coli and S. aureus in agar plates, showing only antimicrobial activity against the latter. The goal is to develop materials that can exhibit antimicrobial, and skin regenerative properties provided by the presence of zinc ions and allantoin, respectively.Authors acknowledge financial support from the MCIN/AEI/10.13039/501100011033 (Spain, project PID2019-105479RB-I00) and FEDER (EU) funds (project MAT2015-71117-R). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). EPR acknowledges the CNPq (Brazil) for the fellowship 204360/2014-5. S. R. G. B. was supported by grant POSTDOC_21_00069 funded by Consejería de Universidad, Investigación e Innovación, Junta de Andalucı́a (Spain). We are thankful to C3UPO for the HPC facilities provided. Authors also acknowledge Dr. I Sobrados and Dr. V. Díez for valuable technical assistance and discussion in the NMR study.Peer reviewe

Effect of diol isomer/water mixtures on the stability of Zn-MOF-74

The stability of metal-organic frameworks is a key factor in many applications in some fields that require working under harsh conditions. It is known that a large number of MOFs are vulnerable to humid air. It means that when they are exposed to water, a structural collapse of the crystal happens. In this work, Molecular Dynamics simulations using a reactive force field have been performed to study the stability of MOF-74 against the adsorption of catechol, resorcinol and hydroquinone in the presence of water. We reproduced the water instability of Zn-MOF-74 and we studied the resistance of the structure. Our simulations showed that the three isomers generate a volume change in the framework but the structural collapse does not happen. In contrast, for water-isomer mixtures, there is structural collapse. Not only do catechol, resorcinol and hydroquinone not behave as stabilizing agents but they do enhance the hydration effect on the structure

RUPTURA: simulation code for breakthrough, ideal adsorption solution theory computations, and fitting of isotherm models

We present the RUPTURA code (https://github.com/iraspa/ruptura) as a free and open-source software package (MIT license) for (1) the simulation of gas adsorption breakthrough curves, (2) mixture prediction using methods like the Ideal Adsorption Solution Theory (IAST), segregated-IAST and explicit isotherm models, and (3) fitting of isotherm models on computed or measured adsorption isotherm data. The combination with the RASPA software enables computation of breakthrough curves directly from adsorption simulations in the grand-canonical ensemble. RUPTURA and RASPA have similar input styles. IAST is implemented near machine precision but we also provide several explicit mixture prediction methods that are non-iterative and potentially faster than IAST. The code supports a wide variety of isotherm models like Langmuir, Anti-Langmuir, BET, Henry, Freundlich, Sips, Langmuir-Freundlich, Redlich-Peterson, Toth, Unilan, O'Brian &amp; Myers, Asymptotic Temkin, and Bingel &amp; Walton. The isotherm model parameters can easily be obtained by the fitting module. Breakthrough plots and animations of the column properties are automatically generated. In addition to highlighting the code, we also review all the developed techniques from literature for mixture prediction, breakthrough simulations, and isotherm model fitting, and provide a tutorial discussing the workflows.</p

Modelling of adsorbate-size dependent explicit isotherms using a segregated approach to account for surface heterogeneities

Ideal Adsorbed Solution Theory (IAST) is a common method for modelling mixture adsorption isotherms based on pure component isotherms. When the adsorbent has distinct adsorption sites, the segregated version of IAST (SIAST) provides improved adsorbed loadings compared to IAST. We have adopted the concept of SIAST and applied it to an explicit isotherm model which takes into account the different sizes of the adsorbates: the so called Segregated Explicit Isotherm (SEI). The purpose of SEI is to have an explicit adsorption model that can consider both size-effects of the co-adsorbed molecules and surface heterogeneities. In sharp contrast to IAST and SIAST, no iterative scheme is required in case of SEI, which leads to much faster simulations. A comparative study has been performed to analyse the adsorption isotherms calculated using these three methods. The adsorbed loadings predicted by SEI and SIAST are in excellent agreement with the Grand-Canonical Monte Carlo (GCMC) simulation data. The loadings estimated by IAST show considerable deviations from the GCMC data at high pressures. Breakthrough curve modelling is used to compare the effects of these three models at dynamic conditions. The explicit model (SEI) leads to the fastest simulation run time, followed by SIAST.</p

TAMOF-1 as a Versatile and Predictable Chiral Stationary Phase for the Resolution of Racemic Mixtures

Metal-organic frameworks (MOFs) have become promising materials for multiple applications due to their controlled dimensionality and tunable properties. The incorporation of chirality into their frameworks opens new strategies for chiral separation, a key technology in the pharmaceutical industry as each enantiomer of a racemic drug must be isolated. Here, we describe the use of a combination of computational modeling and experiments to demonstrate that high-performance liquid chromatography (HPLC) columns packed with TAMOF-1 as the chiral stationary phase are efficient, versatile, robust, and reusable with a wide array of mobile phases (polar and non-polar). As proof of concept, in this article, we report the resolution with TAMOF-1 HPLC columns of nine racemic mixtures with different molecular sizes, geometries, and functional groups. Initial in silico studies allowed us to predict plausible separations in chiral compounds from different families, including terpenes, calcium channel blockers, or P-stereogenic compounds. The experimental data confirmed the validity of the models and the robust performance of TAMOF-1 columns. The added value of in silico screening is an unprecedented achievement in chiral chromatography.</p

Zeolites for CO2-CO-O2 separation to obtain CO2-neutral fuels

Carbon dioxide release has become an important global issue due to the significant and continuous rise in atmospheric CO2 concentrations and the depletion of carbon-based energy resources. Plasmolysis is a very energy-efficient process for reintroducing CO2 into energy and chemical cycles by converting CO2 into CO and O2 utilizing renewable electricity. The bottleneck of the process is that CO remains mixed with O2 and residual CO2. Therefore, efficient gas separation and recuperation are essential for obtaining pure CO, which, via water gas shift and Fischer-Tropsch reactions, can lead to the production of CO2-neutral fuels. The idea behind this work is to provide a separation mechanism based on zeolites to optimize the separation of carbon dioxide, carbon monoxide, and oxygen under mild operational conditions. To achieve this goal, we performed a thorough screening of available zeolites based on topology and adsorptive properties using molecular simulation and ideal adsorption solution theory. FAU, BRE, and MTW are identified as suitable topologies for these separation processes. FAU can be used for the separation of carbon dioxide from carbon monoxide and oxygen and BRE or MTW for the separation of carbon monoxide from oxygen. These results are reinforced by pressure swing adsorption simulations at room temperature combining adsorption columns with pure silica FAU zeolite and zeolite BRE at a Si/Al ratio of 3. These zeolites have the added advantage of being commercially available

Simulation input files and datasets for the article: "RUPTURA: Simulation Code for Breakthrough, Ideal Adsorption Solution Theory Computations, and Fitting of Isotherm Models".

This folder contains:1) examples for simulating breakthrough curves, estimating mixture adsorption isotherms and fitting of pure component isotherms. These examples are also present in the open source code RUPTURA (https://github.com/iRASPA/RUPTURA.git).2) datasets for validating the breakthrough curve model (Separation of 2mC4 and 2mC5 in MFI-type zeolite at 473K and 5 bar). Experimental datasets are obtained from the following reference:E. Jolimaitre, K. Ragil, M. Tayakout-Fayolle, and C. Jallut. Separation of mono and dibranched hydrocarbons on silicalite. AIChE J., 48:1927–1937, 2002

Sample simulation input file and data sets for the article: "Modelling of adsorbate-size dependent explicit isotherms using a segregated approach to account for surface heterogeneities."

This folder contains simulation input files and datasets for calculation of pure component isotherms, mixture isotherms and breakthrough curves for the separation of:1) CO2 and C3H8 molecules in MOR-type zeolite at 300K2) nC4 and 2mC3 molecules in MFI-type zeolite at 400

Looking at the "water-in-Deep-Eutectic-Solvent" System: A Dilution Range for High Performance Eutectics

Deep eutectic solvents (DESs) are lately expanding their use to more demanding applications upon aqueous dilution thanks to the preservation of the most appealing properties of the original DESs while overcoming some of their most important drawbacks limiting their performance, like viscosity. Both experimental and theoretical works have studied this dilution regime, the so-called "water-in-DES" system, at near-to stoichiometric amounts to the original DES. Herein, we rather studied the high-dilution range of the "water-in-DES" system looking for enhanced performance because of the interesting properties (a further drop of viscosity) and cost (water is cheap) that it offers. In particular, we found that, in the "water-in-DES" system of a ternary DES composed of resorcinol, urea and choline chloride (e.g., RUChClnW, where n represents mol of water per mole of ternary DES), the tetrahedral structure of water was distorted as a consequence of its incorporation, as an additional hydrogen bond donor or hydrogen bond acceptor, into the hydrogen bond complexes formed among the original DES components. DSC confirmed the formation of a new eutectic, with a melting point below that of its respective components, the original ternary DES and water. This depression in the melting point was also observed in the same regime of reline and malicine aqueous dilutions, thus suggesting the universality of this simple procedure (i.e., water addition to reach the high-dilution range of the "water-in-DES" system) to obtain deeper eutectics eventually providing enhanced performances and lower cost

Ordered_Nanoporous_Metals_SI.zip from Understanding the stability and structural properties of ordered nanoporous metals toward their rational synthesis

Ordered Nanoporous Metals (ONMs) form a new family of nanoporous materials composed only by pure metals. The expected impact is huge from combining the ordered nanopore structure of MOFs, zeolites and carbon schwartzites with the robustness and electronic conductivity of metals. Little is known about their stability and structural features. Here we address these points to provide clues toward their rational synthesis, introducing an automatic atomistic design that uses model building and molecular dynamics structural relaxation, and it is validated against the experimentally known ONMs. Analysing the properties of the 10 stable structures out of the 17 studied (14 of which are designed in this work) using four noble metals (Pt, Pd, Au and Ag), we have deciphered some key elements and structural descriptors that provide guidelines for the experimental synthesis of ONMS. The long-lived metastability of the stable ONMs is evidenced by the high free energy landscape, computed via Metadynamic simulations. The new ONMs permit molecular diffusion of various molecules of industrial relevance, increasing the expectation for their use in catalysis, separation, nanofiltration, batteries, fuel cells, etc. Stable low-cost ONMs are predicted using Earth-abundant Ni metal, which maintains the main features of their relative noble metal forms