Supramolecular Hydrogels Consisting of Nanofibers Increase the Bioavailability of Curcuminoids in Inflammatory Skin Diseases

The low bioavailability of curcuminoids (CCMoids) limits their use in the treatment of inflammatory skin diseases. Our work shows that this constraint can be overcome upon their incorporation into supramolecular hydrogels assembled from a gemini-imidazolium amphiphilic gelator. Three structural CCMoid analogues were used to prepare supramolecular hydrogels, and it was observed that the concentration of both the gelator and CCMoid and the proportion of solvents influence the self-assembly process. Moreover, the mechanical properties of the nanostructured gels were studied to find the optimum gels, which were then further characterized microscopically, and their ability to release the CCMoid was evaluated. The physicochemical properties of the CCMoids play a fundamental role in the interaction with the gelator, influencing not only the gelation but also the morphology at the microscopic level, the mechanical properties, and the biopharmaceutical behavior such as the amount of CCMoid released from the gels. The nanostructured supramolecular hydrogels, which contain the CCMoids at much lower concentrations (μg/mL) in comparison to other products, promote the penetration of the CCMoids within the skin, but not their transdermal permeation, thus preventing any possible systemic effects and representing a safer option for topical administration. As a result, the CCMoid-containing hydrogels can effectively reduce skin inflammation in vivo, proving that these supramolecular systems are excellent alternatives in the treatment of inflammatory skin diseases.This work was supported by the projects PID2020-115663GB-C3-2, PID2019-108794GB-I00, and PID2020–115631GB-I00 funded by MCIN/AEI/10.13039/501100011033 from the Ministerio de Ciencia e Innovación. We thank AGAUR for a grant to consolidated research groups 2017SGR1277. A.G.-C. and N.A.-A. acknowledge the financial support from the Spanish Ministry Science, through the “Severo Ochoa” Programme for Centres of Excellence (FUNFUTURE) (2020-2023). A.G.-C. also acknowledges a Ramon y Cajal Grant (RYC-2017-22910).With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Examining the adsorption of gases into solid crystalline molecular copper(II) 3,5-bis(trifluoromethyl)benzoate derivatives

Two copper(II) complexes, both involving the anionic 3,5-bis(trifluoromethyl)benzoate ligand (TFMBz), have been prepared and their structure elucidated by single crystal-X ray diffraction. [Cu(TFMBz)2(ISNA)2] (1) is a mononuclear complex, in which the sphere of coordination of Cu(II) is completed by two neutral isonicotinamide (ISNA) auxiliary ligands. Hydrogen bonding formed between auxiliary ISNA ligands determines the formation of a 2D supramolecular network. [Cu2(TFMBz)4(DMSO)2] (2) is a binuclear complex, in which the four carboxylate ligands define the typical paddle wheel structure often found in copper complexes, containing also the ancillary dimethyl sulfoxide (DMSO) ligand in axial positions. The elucidated crystallographic data provide the static view of the crystal structures, which reveals only non-interconnected voids for both materials. Even that, compound 1 shows an appreciable adsorption of CO2 at 273 K (ca. 1 CO2 molecule/Cu atom at 100 kPa), concomitant with a reduced adsorption of Ar or N2 under similar conditions, which implies a considerable degree of selectivity for CO2. Moreover, 1 does not adsorb N2 or Ar at 77 K and 100 kPa. This behavior suggests that the stablished intermolecular hydrogen bonds rest flexibility and dynamism to 1 at low temperature. Contrarily, increasing the temperature transient porosity is originated, which allows guest molecules to diffuse through the cavities. Compound 2 shows adsorption of N2 and Ar at 77 K, indicating that vibrations in the network and rotation of some CF3 groups, necessary to favor adsorbate diffusion, are still feasible at this low temperature.This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019-000917-S) and the Spanish National Plan of Research with project PID2020-115631 GB-I00. The measurements for the elucidation of the crystal structures and SPXRD patterns were performed at the XALOC and NOTOS beamlines of the ALBA Synchrotron, respectively, with the collaboration of ALBA staff.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Editorial: Microencap2525sulation for Biomedical Applications

This article is part of the Research Topic Microencapsulation for Biomedical ApplicationsPeer reviewe

Determination of Curcuminoids by Liquid Chromatography with Diode Array Detection: Application to the Characterization of Turmeric and Curry Samples

Background: A simple, rapid and efficient method for the determination of curcumin and other polyphenols in turmeric and curry samples was here developed. The method relied on sample extraction with methanol and extract analysis by liquid chromatography with diode array detection (HPLC-DAD). Methods: The separation of components was carried out in reversed-phase mode using an elution gradient based on 0.1% (v/v) formic acid aqueous solution and acetonitrile as the components of the mobile phase. Chromatograms were recorded at 420 nm for specific monitoring of curcumin and related compounds. Results: Extraction and separation conditions were optimized by experimental design and multicriteria response functions. Figures of merit were established under the selected experimental conditions. In general, repeatability of peak areas were better than 0.4%, detection limits were below 0.006 mg L-1 and quantitative recoveries expressed as a percentage were about 100 ± 2. The method was applied to quantify curcuminoids in commercial samples. It was found that apart from curcumin, demethoxycurcumin and bisdemethoxycurcumin, other related molecules also occurred in the samples. In this regard, a tentative elucidation of possible unknown curcuminoids was attempted by liquid chromatography coupled to mass spectrometry. Conclusion: Differences in the compositional profiles among samples were encountered to be relevant, so that the resulting HPLC-DAD data was exploited for chemometric characterization of turmeric and curry samples. Samples were successfully discriminated according to matrix types, species varieties and origins.This work was financed by the Spanish Ministry of Economy and Competitiveness through the projects CTQ2014-56324-CO2-P1, MAT2014-53500-R, MAT2016-77852-C2-1-R and the “Severo Ochoa” Programme for Cen-ters of Excellence in R&D (SEV-2015-0496), and by Gener-alitat de Catalunya with project 2014SGR377.Peer reviewe

[Zn2Ac2(μ-Ac)2(bpymb)]n (Ac, acetate; bpymb, 1,4-bis(4-pyridylmethyl)benzene), a 2D coordination polymer obtained with a flexible N,N’-ditopic bipyridine linker

The combination of the flexible N,N’-ditopic ligand 1,4-bis(4-pyridylmethyl)benzene (bpymb) with zinc(II) acetate (ZnAc) affords the synthesis of the two-dimensional coordination polymer [Zn2Ac2(μ-Ac)2(bpymb)]n, which was structurally characterized by single crystal XRD. In the resolved structure, the molar ratio metal:ligand was 2:1 for Ac:Zn. However, half of the acetate units are acting as bridging ligands, which allows the building of a layered structure. The description of this new structure increases the numerous family of compounds involving zinc acetate and a ditopic N,N’- ligand, and demonstrates a new possible architecture. The obtained coordination polymer was also characterized by elemental analysis, ATR-FTIR spectroscopy and TGA analysis. Besides, the photoluminescence properties of this compound where measured, showing that the weak photoluminescence of the free bpymb ligand increases after polymer formation.This work was financed by the Spanish National Plan of Research with project CTQ2017-83632. C.D. and A.M.L.-P. acknowledge the financial support from the Spanish MEC, through the Severo Ochoa Program for Centres of Excellence in R&D FUNFUTURE (CEX2019-000917-S). ALBA synchrotron is acknowledged for the provision of beam time.Peer reviewe

Photocatalytic Hydrogen Production using Porous 3D Graphene-Based Aerogels Supporting Pt/TiO2 Nanoparticles

Composites involving reduced graphene oxide (rGO) aerogels supporting Pt/TiO2 nanoparticles were fabricated using a one-pot supercritical CO2 gelling and drying method, followed by mild reduction under a N2 atmosphere. Electron microscopy images and N2 adsorption/desorption isotherms indicate the formation of 3D monolithic aerogels with a meso/macroporous morphology. A comprehensive evaluation of the synthesized photocatalyst was carried out with a focus on the target application: the photocatalytic production of H2 from methanol in aqueous media. The reaction conditions (water/methanol ratio, catalyst concentration), together with the aerogel composition (Pt/TiO2/rGO ratio) and architecture (size of the aerogel pieces), were the factors that varied in optimizing the process. These experimental parameters influenced the diffusion of the reactants/products inside the aerogel, the permeability of the porous structure, and the light-harvesting properties, all determined in this study towards maximizing H2 production. Using methanol as the sacrificial agent, the measured H2 production rate for the optimized system (18,800 µmolH2h-1gNPs-1) was remarkably higher than the values found in the literature for similar Pt/TiO2/rGO catalysts and reaction media (2000-10,000 µmolH2h-1gNPs-1).This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019–000917-S) and the Spanish National Plan of Research with project PID2020–115631GB-I00. We would like to thank the scientific collaboration under LA/P/0045/2020 (ALiCE), UIDB/50020/2020, and UIDP/50020/2020 (LSRE-LCM), financed by national funds through FCT/MCTES (PIDDAC). Márta Kubovics acknowledges the financial support from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Cofund grant (agreement no MSCA-COFUND-DP/0320-754397) and the Short Term Scientific Mission (STSM) from the Greenering network by the COST Association. This work has been performed in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by Márta Kubovics.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Graphene Oxide/Polyethylenimine Aerogels for the Removal of Hg(II) from Water

This article reports the synthesis of an aerogel involving reduced graphene oxide (rGO) and polyethylenimine (PEI), and describes its potential application as an effective sorbent to treat Hg(II) contaminated water. The rGO/PEI sorbent was synthetized using a supercritical CO2 method. N2 physisorption, electron microscopy, and elemental mapping were applied to visualize the meso/macroporous morphology formed by the supercritical drying. The advantages of the synthetized materials are highlighted with respect to the larger exposed GO surface for the PEI grafting of aerogels vs. cryogels, homogeneous distribution of the nitrogenated amino groups in the former and, finally, high Hg(II) sorption capacities. Sorption tests were performed starting from water solutions involving traces of Hg(II). Even though, the designed sorbent was able to eliminate almost all of the metal from the water phase, attaining in very short periods of time residual Hg(II) values as low as 3.5 µg L-1, which is close to the legal limits of drinking water of 1-2 µg L-1. rGO/PEI exhibited a remarkably high value for the maximum sorption capacity of Hg(II), in the order of 219 mg g-1. All of these factors indicate that the designed rGO/PEI aerogel can be considered as a promising candidate to treat Hg(II) contaminated wastewater.This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019–000917-S) and the Spanish National Plan of Research with project PID2020–115631GB-I00. A.B. acknowledges the financial support of the FPI Spanish grant BES-2017-081148, and from the European Union’s Horizon 2020 research and innovation program under the COST action Greenering (CA18224). G. Gonçalves and B. Henriques thank the Fundação para a Ciência e Tecnologia (FCT) for the Program Stimulus of Scientific EmploymentIndividual Support (CEECIND/01913/2017 and CEECIND/03511/2018, respectively). The financial support of TEMA through the projects UIDB/00481/2020 and UIDP/00481/2020 and of REQUIMTE by the project UIDB/50006/2020 from FCT and CENTRO-01-0145-FEDER-022083— Centro Portugal Regional Operational Programme (Centro 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

One-dimensional metal–organic frameworks built by coordinating 2,4,6-tris(4-pyridyl)-1,3,5-triazine linker with copper nodes: CO2 adsorption properties

The reaction between 2,4,6-tris(4-pyridyl)-1,3,5-triazine (4-tpt) and copper(II) hexafluoroacetylacetone (Cu(hfa)2) yields two different 1D metal–organic frameworks (MOFs), [(Cu(hfa)2)2(4-tpt)]n (1) and [Cu(hfa)2(4-tpt)]n (2). The Cu:4-tpt ratio in the new MOFs is determined by the reaction medium, particularly, the solvent used. The two compounds have been fully characterized, including crystal structure elucidation. [(Cu(hfa)2)2(4-tpt)]n (1), with a 2:1 Cu:4-tpt ratio, could be precipitated in either 1,1,2-trichloroethane or supercritical CO2. In (1), 4-tpt shows a tritopic coordination mode, but only half of the Cu(hfa)2 subunits act as a node, thus connecting two 4-tpt and giving a 1D network. The other half of Cu(hfa)2 subunits are connected only to one pyridine and thus protrude along the chains. The later Cu(hfa)2 fragments show a labile character and can be dissolved in diethyl ether to give the second MOF [Cu(hfa)2(4-tpt)]n (2), with a 1:1 Cu:4-tpt ratio. The compound (2) has also a 1D structure, with all the incorporated copper atoms acting as nodes. In this case, the packing of the chains defines accessible channels, which are perpendicular to the chain axis. After activation, N2 adsorption/desorption measurements at 77 K confirm the microporous character of (2) with an apparent surface area of 190 m2 g−1. Besides, at 273 K this material clearly shows a significant adsorption of CO2 prompted by noncoordinated nitrogen in the triazine linker.This work was supported by the Spanish Ministry of Science and Innovation (MICINN) through the Severo Ochoa Program for Centers of Excellence (CEX2019-000917-S) and the Spanish National Plan of Research with project PID2020-115631GB-I00. The measures for the elucidation of the crystal structures were performed at MSPD and XALOC beamlines at ALBA Synchrotron with the collaboration of ALBA staff.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Meso/microporous MOF@graphene oxide composite aerogels prepared by generic supercritical CO2 technology

The increasing complexity in composition and structure of modern porous nanocomposite materials requires the development of advanced technologies that allow the simultaneous treatment of dissimilar compounds, not only with unlike composition but also involving different classes of pores, e.g., micro and mesopores. This work shows that supercritical CO2 (scCO2) technology can be used as generic processing aid to obtain composites involving non-reduced graphene oxide (GO) and metal organic frameworks (MOFs) in the form of aerogels with hierarchical porosity. Hybrid aerogels are formed by either depositing (ex situ) or growing (in situ) MOF nanocrystals onto the surface of 2D GO nanosheets. The archetypal hydrophilic HKUST-1 and UiO-66 and hydrophobic ZIF-8 microporous MOFs are chosen to exemplify the method possibilities. The ex situ route was adequate to prepare hydrophilic MOFs@GO homogeneous composites, while the in situ approach must be used to prepare hydrophobic MOFs@GO aerogels. Moreover, the scCO2 methodology should be adjusted for each studied MOF in regard of the organic solvent used to disperse the nanoentities constituting the composite. The end-products are obtained in the form of aerogels mimicking the shape of the recipient in which they are contained. The products are characterized in regard of structure by X-ray diffraction, textural properties by low temperature N2 adsorption/desorption and morphology by electronic microscopy.This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (SEV-2015-0496 and CEX2019-000917-S) and the Spanish National Plan of Research with projects CTQ2017-83632, PID2020-115631GB-I00. This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by A.B., A.R. and J.F.; A.B. and A.R. acknowledge FPI grants.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe