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The common use of Li-ion batteries (LIBs) in portable devices and electric vehicles is promoting an exponential growth of the rechargeable batteries market. Their use in electric vehicles while not...

The aim of this featured article is to illustrate some of the most recent applications of deep eutectic solvents (DESs) in the synthesis of carbon and carbon composites. DESs can be obtained by the complexation of quaternary ammonium salts with hydrogen-bond donors. DESs have typically been referred to as a related class of ionic liquids because they share many properties. However, DESs present the advantage of easier and low-cost preparation. Moreover, their compositional flexibility can eventually be translated into materials that provide advanced functionalities and/or tailored hierarchical structures. Interestingly, the use of the liquid binary mixtures of DESs and H2O for the preparation of carbon materials plays a critical role with regard to the achievement of some particular porous morphologies. Herein, we will also summarize some recent studies performed on DES/H2O liquid binary mixtures, revealing the possibility of obtaining new eutectic mixtures upon the simple addition of water to DESs while keeping the DES contents at a certain pseudo-concentrated range. This finding will pave the way to novel applications, especially in those fields in which the preparation of high-tech products via low-cost processes is critical. We hope that this featured article will encourage scientists to explore the promising perspectives offered by DESs and aqueous dilutions thereof.

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.

Brillouin and NMR spectroscopy were used to explore transitions in the structuring of liquid binary mixtures composed of water and a deep eutectic solvent (DES) known as malicine and composed of malic acid (MA) and choline chloride (ChCl). Malicine/H2O binary mixtures were studied for DES contents ranging from 100 to 40 wt%. Data representation of sound propagation velocities – obtained from Brillouin spectroscopy – versus DES content exhibited two well-differentiated linear regimes above and below ca. 70 DES wt% while transitioning from a “water-in-DES” system to a “DES-in-water” one along with dilution. Two linear regimes intersecting at ca. 70 DES wt% were also observed when representing the self-diffusion coefficients versus malicine contents, with MA and ChCl – and even water – exhibiting nearly identical self-diffusion coefficients for contents above 70 wt%, that diverged for contents below 70 wt%. Interestingly, further insights about this behaviour were provided by spin-lattice relaxation time of MA, also revealing the occurrence of hydrophobic hydration around non-polar moieties as in other aqueous binary mixtures of non-ionic H-bond co-solvents – e.g., DMSO:H2O or dioxane:water.

Liquid binary mixtures of deep eutectic solvents (DESs) with H2O are lately attracting the interest of many research works because of the improved performance that these dilutions demonstrated in number of application – e.g., catalysis, separations, or biochemistry, among others – as compared to their respective neat DES counterparts. Interestingly, molecular simulations have revealed that, despite the macroscopically homogeneous appearance of the DES/H2O binary mixtures, phase segregation may occur at the nanoscale. Spectroscopic studies corroborating this event in this sort of mixtures are basically limited to NMR-based ones determining diffusion coefficients and some recent Brillouin spectroscopic studies performed for a quite short list of binary DESs – i.e., those composed of one single hydrogen bond donor (HBD) and one single hydrogen bond acceptor (HBA), being urea-choline-chloride-based DES the most widely studied. Interestingly, NMR data such as chemical shifts and relaxation times have also proved quite useful for the study of liquid binary mixtures different than DES-based ones – e.g., ionic-liquid-based ones. Herein, we have obtained a full set of NMR data – chemical shifts, diffusion coefficients and relaxation times – from liquid binary mixtures of H2O and a ternary DESs, in this particular case one composed of two HBD – e.g., resorcinol and hexylresorcinol – and one HBA – tetraethyl ammonium bromide. Good correlation among different NMR data as well as between NMR and Brillouin data was found in the determination of the DES content at which phase segregation occurs.

Producción Científica, A new generation of confined palladium(II) catalysts covalently attached inside of porous organic polymers (POPs) has been attained. The synthetic approach employed was straightforward, and there was no prerequisite for making any modification of the precursor polymer. First, POP-based catalytic supports were obtained by reacting one symmetric trifunctional aromatic monomer (1,3,5-triphenylbenzene) with two ketones having electron-withdrawing groups (4,5-diazafluoren-9-one, DAFO, and isatin) in superacidic media. The homopolymers and copolymers were made using stoichiometric ratios between the functional groups, and they were obtained with quantitative yields after the optimization of reaction conditions. Moreover, the number of chelating groups (bipyridine moieties) available to bind Pd(II) ions to the catalyst supports was modified using different DAFO/isatin ratios. The resulting amorphous polymers and copolymers showed high thermal stability, above 500 °C, and moderate–high specific surface areas (from 760 to 935 m2 g–1), with high microporosity contribution (from 64 to 77%). Next, POP-supported Pd(II) catalysts were obtained by simple immersion of the catalyst supports in a palladium(II) acetate solution, observing that the metal content was similar to that theoretically expected according to the amount of bipyridine groups present. The catalytic activity of these heterogeneous catalysts was explored for the synthesis of biphenyl and terphenyl compounds, via the Suzuki–Miyaura cross-coupling reaction using a green solvent (ethanol/water), low palladium loads, and aerobic conditions. The findings showed excellent catalytic activity with quantitative product yields. Additionally, the recyclability of the catalysts, by simply washing it with ethanol, was excellent, with a sp2–sp2 coupling yield higher than 95% after five cycles of use. Finally, the feasibility of these catalysts to be employed in tangible organic reactions was assessed. Thus, the synthesis of a bulky compound, 4,4′-dimethoxy-5′-tert-butyl-m-terphenylene, which is a precursor of a thermal rearrangement monomer, was scaled-up to 2 g, with high conversion and 96% yield of the pure product., Agencia Estatal de Investigación (projects PID2019-109403RB-C22, MAT2016-76413-C2-R2, CTQ2017-89217- P and MAT2016-76413-C2-R1), Junta de Castilla y León (project VA038G18)

Oxygen-enriched boron carbonitrides – known as boron carbon oxinitrides, BCNOs – have exhibited remarkable properties with numerous works reporting on their performance as phosphors and some few ones as H2-adsorbents. However, the study of BCNOs capability for CO2 uptaking has yet to be achieved. Herein, we have designed a simple process for preparation of freestanding three-dimensional (3D) BCNO structures via pyrolysis of supramolecular gels formed by H-bonding of melamine, boric acid and glucose. The 3D porous materials obtained by pyrolysis of supramolecular gels containing glucose exhibited a seaweed-like 3D structure formed by BCNO nanocrystals embedded within a carbonaceous matrix with a certain content of amorphous hydrogenated carbon. The particularly narrow porosities exhibited by these samples proved effective for CO2 adsorption with uptakes of up to ca. 1.8 mmol/g at 25 °C. More interestingly, those samples prepared with high concentration of glucose behaved as molecular sieves and exhibited an excellent performance for CO2–CH4 separation, especially at low pressures with kH values of up to 1.04∙103. This work was supported by MINECO/FEDER (Project Numbers MAT2015-68639-R and MAT2016-80285-P). N. López-Salas also acknowledges MINECO/FEDER for a FPI research contract. C. Cuadrado-Collados and J. Gandara-Loe acknowledge UA and GV (GRISOLIAP/2016/089) for their respective research contracts.

Genipin is used to simultaneously crosslink chitosan, amine-containing osmium redox complex and glucose oxidase on graphite disks to produce enzyme-based electrodes for glucose oxidation. The enzyme electrodes produce glucose oxidation current densities of 730 µA cm−2 in 50 mM phosphate buffered saline (150 mM NaCl, pH 7.4, 37 °C) containing 100 mM glucose at an applied potential of 0.45 V (vs. Ag/AgCl), higher than the 440 µA cm−2 for conventional poly(ethylene glycol) diglycidyl ether (PEGDGE) epoxy ring-opening cross-linked films. Addition of multiwalled carbon nanotubes results in current response as high as 4.9 ± 0.3 mA cm−2 in 100 mM glucose. The genipin cross-linked hydrogels deliver a 3 fold increase in stability for continuous amperometric current production over a 20 h period when compared to PEGDGE cross-linked hydrogels. Genipin provides an effective route for simultaneous crosslinking glucose oxidase, chitosan and the redox complex while further optimisation of the crosslinking process holds promise for application of the enzyme electrodes as fuel cell and sensor devices. Keywords: Genipin, Glucose oxidase, Chitosan, Bioelectrocatalysis, Glucose biosensor

The incorporation of multi-walled carbon nanotubes (MWCNTs) into chondroitin sulphate-based scaffolds and the effect on the structural, mechanical, conductive, and thermal properties of the resulting scaffolds is investigated. Three-dimensional hierarchical materials are prepared upon the application of the ice segregation-induced self-assembly (ISISA) process. The use of ice as structure-directing agents avoids chemicals typically used for this purpose (e.g., surfactants, block copolymers, etc.), hence, emphasising the green features of this soft-templating approach. We determine the critical parameters that control the morphology of the scaffolds formed upon ice-templating (i.e., MWCNTs type, freezing conditions, polymer and MWCNT concentration). MWCNTs are surface functionalized by acidic treatment. MWCNT functionalization is characterized by Raman, Fourier transfer infrared (FTIR) and X-ray Photoelectron (XPS) spectroscopies. Scanning electron microscopy (SEM) analysis and porosity studies reveal that MWCNT content modifies the morphology of the macroporous structure, which decreases by increasing MWCNT concentration. Differences in scaffold morphology should be translated into their conductivity and mechanical properties. As a general trend, the Young’s modulus and the electrical conductivity of the scaffolds increase with the MWCNT content. Preliminary biocompatibility tests with human osteoblast-like cells also reveal the capability of these structures to support cell growth., The authors acknowledge Spanish MINECO/FEDER (grants MAT2011-25329, MAT2012-34811 and MAT2015-68639-R) for financial support. S.N. acknowledges CAPES for a PNPD fellowship. M.C.S. is greatly indebted to the Instituto de Salud Carlos III-MINECO-FEDER a Miguel Servet I contract (CP13/00060). Ricardo Jiménez (from the Instituto de Ciencia de Materiales de Madrid-CSIC) and Sylvia Gutiérrez (from the Centro Nacional de Biotecnología-CSIC) are acknowledged for their assistance with mechanical test and confocal microscopy studies, respectively. Authors would like to express a hearty and posthumous acknowledgement to Fernando Pinto from the Instituto de Ciencias Agrarias (CSIC) for his expert assistance with SEM studies and his sincere and constant support., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

Deep eutectic solvents (DESs) offer a suitable alternative to conventional solvents in terms of both performance and cost-effectiveness. Some DESs also offer certain green features, the greenness of which is notoriously enhanced when combined with water. Aqueous DES dilutions are therefore attracting great attention as a novel green medium for biotechnological processes, with the aqueous dilutions of reline-a DES composed of urea and choline chloride-being one of the most studied systems. Despite their macroscopic homogeneous appearance, both H NMR spectroscopic studies and molecular dynamics simulations have revealed the occurrence of certain dynamic heterogeneity at a microscopic molecular level. Ultrasonic measurements were also used with the aim of getting further insights but nonconclusive results were obtained. Herein, we have studied aqueous reline dilutions by Brillouin spectroscopy given its proved suitability for detecting local structure rearrangements in liquid mixtures of H-bonded co-solvents. Brillouin spectroscopy revealed the formation of a co-continuous structure resulting from local structure rearrangements and micro-segregation into aqueous and DES phases. Interestingly, there is agreement between H NMR and Brillouin spectroscopy when pointing to the DES content where microphase segregation and formation of co-continuous structures occurred., This work was supported by MINECO (Project Numbers MAT2015-68639-R and MAT2015-65356-C3-1-R) and Comunidad de Madrid Excellence Network (Project Number S2013/MIT-2740). N. López-Salas also acknowledges MINECO/FEDER for a FPI research contract.

This work describes how the preparation of deep eutectic solvents (DES) in its pure state can be accomplished through a simple approach based on the freeze-drying of aqueous solutions of the individual counterparts of DES. DES in its pure state obtained via freeze-drying are studied by (1)H NMR, which reveals the formation of halide ion-hydrogen-bond-donor supramolecular complexes (characteristic of DES), and by cryo-etch-SEM, which provides insight about the capability of aqueous solutions of DES to be segregated in DES and ice upon freezing. The paper also explores the suitability of the freeze-drying approach to incorporate organic self-assemblies (in particular, liposomes of ca. 200 nm) in DES with full preservation of their self-assembled structure. This is not a trivial issue given that amphiphilic molecules tend to be readily dissolved (hence, disassembled) in DES. The strategy proposed in this work is based on the freeze-drying of aqueous solutions containing the individual counterparts of DES and the preformed liposomes (also known as large unilamellar vesicles or LUV). The simplicity of the method should also make it suitable for the incorporation of different self-assembled structures (such other types of vesicles and micelles) in DES in its pure state.

WOS: 000253222200065, Hybrid sol-gel TiO2/organosilica films doped with Cu(II), Fe(II), and Fe(III) phthalocyanines are excellent photocatalysts for the oxidative degradation of organics under visible light irradiation. The films show pronounced stability with the Fe(III)Pc-doped film showing the best performance in the gas-phase mineralization of 2-propanol. The versatile chemistry of both sol-gel materials and phthalocyanines will enable large improvement in terms of performance and technical adaptability of these new photocatalytic devices for future practical application.

This review aims to demonstrate the capability of the ice-segregation-induced self-assembly (ISISA) process for the preparation of materials with highly sophisticated structures (e.g., hierarchical materials exhibiting organization at different scale levels). Cryogenic processes (consisting of the freezing, storage in the frozen state for a definite time, and defrosting of low - or high-molecular-weight precursors, as well as colloid systems, as either a water solution or suspension, or forming a hydrogel) have been widely used for the scaffolds preparation. However, the recent success in the control of the morphology (e.g., by unidirectional freezing in nitrogen liquid) and the possibility to extend the compositional nature of the resulting materials has recently attracted much attention to the ISISA process. Besides, this review aims to exemplify how the aqueous nature of the ISISA process allows for the in-situ incorporation of biological entities which provides not only hierarchy but also functionalit...

The use of scaffolds composed of a major fraction of multiwall carbon nanotubes (MWCNT, up to 89 wt.%) and a minor one of chitosan (CHI), and with a well-defined microchannel porous structure as biocompatible and biodegradable supports for culture growth is described. Cell adhesion, viability and proliferation onto the external surface of MWCNT/CHI scaffolds with C2C12 cell line (myoblastic mouse cell), which is a multipotent cell line able to differentiate towards different phenotypes under the action of some chemical or biological factors, has been evaluated in vitro and quantified by MTT assays. The evolution of the C2C12 cell line towards an osteoblastic lineage in presence of the recombinant human bone morphogenetic protein-2 (rhBMP-2) has also been studied both in vitro (e.g., following the appearance of alkaline phosphatase activity) and in vivo (e.g., by implantation of MWCNT/CHI scaffolds adsorbed with rhBMP-2 in muscle tissue and evaluation of the ectopic formation of bone tissue).

Soft-template approaches have been frequently applied for the preparation of porous carbons. Most of these processes proved highly effective for the preparation of mesoporous carbons with pore diameters below 10 nm but less explored has been the preparation of carbons with mesopores larger than 10 nm. The lack of syntheses providing large and well-interconnected mesopores is by no means a trivial issue because it limits the achievement of materials suitable for applications where pore surface accessibility is crucial – e.g. electrodes in supercapacitors or adsorbents in flow-through systems, among others. In this work, we have used deep eutectic solvents (DESs, a sort of ionic liquid, that are obtained by complexation of quaternary ammonium salts with hydrogen-bond donors) composed of resorcinol, urea and choline chloride for the preparation – via formaldehyde polycondensation and subsequent carbonization – of hierarchical porous carbons with micropores and large mesopores within the 10 to 20 nm range. The formation of large mesopores took place at the polycondensation stage via a spinodal decomposition process where some components forming the DES acted as precursors of the polymer phase, while some other ones were segregated into a polymer depleted phase. Thus, the ultimate dimension of the mesopores was controlled by the mass ratio between the segregated and condensed phases, and this mass ratio by the molar ratio of the components forming the original DES. We have finally demonstrated that carbons with larger mesopores exhibited better performance as electrodes in supercapacitor cells., The authors thank Spanish MINECO (grants MAT2012‐34811 and CTM2014‐56770‐R) for financial support. N. López‐Salas also acknowledges MINECO for a FPI research contract.

Microchannelled 3D architectures composed of multiwall carbon nanotubes (MWCNTs) surface decorated with Pt nanoparticles and chitosan (CHI) are prepared by an ice segregation induced self-assembly (ISISA) process. The microchannelled structures are highly porous (specific gravity ∼10-2) and exhibit excellent electron conductivity (2.5 S·cm-1) thanks to both the high content of MWCNTs (up to 89 wt %) and their interconnection. The Pt/MWCNT/CHI 3D architectures provide remarkable performance as anodes for a direct methanol fuel cell (DMFC).

The current work makes use of different fluorescent reporter molecules and fluorescent spectroscopic techniques to characterize the thermotropic, physical, and dynamical properties of large unilamellar liposomes formed from either 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-glycerol] (DMPG) encapsulated in sol-gel matrixes. In particular, cooperativity of the phase transition is analyzed from steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH), the interfacial properties are studied by measuring the spectral shift of Laurdan, and the structural organization (heterogeneity) of the lipid bilayer is determined from the fluorescence lifetime of trans-parinaric acid (t-PnA). In addition, information regarding order and dynamical properties in the bulk hydrophobic core is obtained from time-resolved fluorescence anisotropy of t-PnA and 3-(4-(6-phenyl)-1,3,5-hexatrienyl)-phenylpropionic acid (PA-DPH). The spectroscopic study reveals that upon encapsulation, the basic thermodynamic properties as well as the fluidity of the lipid bilayer practically remain intact for DMPG liposomes but not for DMPC liposomes, whose lipid bilayer exhibits large gel-fluid heterogeneity. On the basis of these experimental results, electrostatic interactions between phospholipid polar heads and the porous surface of the host matrix seem to play a capital role for the preservation of the structural integrity of encapsulated bilayer.

We have studied the suitability of a cryogenic process (e.g., ice-segregation-induced self-assembly, ISISA) for preparation of polyvinyl alcohol (PVA) scaffolds with in situ immobilized bacteria (e.g., Escherichia coli). Confocal fluorescence microscopy and impedance measurements were used to evaluate the extension of bacteria proliferation within the scaffold macrostructure. The bacteria efficiency for colonization of the scaffold macrostructure is compared for bacteria immobilized with and without the use of additional cryoprotectans. Cryoprotection by bacteria entrapment in alginate beads containing glucose results in a significant improvement (more than 2-fold as compared to non-cryoprotected) of bacteria proliferation within the PVA scaffold. Results are also compared with the most widely used method for cells colonization of scaffolds; i.e., soaking of a preformed PVA scaffold in bacteria culture medium.

Ultralightweight (specific gravity 8.0 × 10–2) and highly conductive (1.4 S cm–1) MWCNT scaffolds exhibited remarkable biocompatibility for E. coli which allows for bacteria immobilization and proliferation within its microchanneled structure. The above-mentioned features make these scaffolds potentially useful as electrodes in microbial fuel cells (MFCs).

Rhodamine B (RB) nanoparticles entrapped in hybrid glasses show enhanced fluorescent emission (approximately 220-fold larger than that of single RB molecules) thanks to the configuration control of the self-assembled aggregates that form the supramolecular architecture of the nanoparticles. The fluorescence performance reported in this work is around 1 order of magnitude larger than that recently reported for fluorescent Nile Red nanoparticles. The fluorescence enhancement results from the use of a highly efficient fluorescent dye such RB and the formation of larger nanoparticles. Note that the later implies the presence of a large number of emitting centers involved in the fluorescence emission.

Biocompatibility is an important issue that still needs research if one desires to fully preserve the metabolic activity of cells encapsulated in any type of material. Spectroscopic techniques (e.g., NMR and fluorescence) have been used to study the viability decrease upon aging time of bacteria encapsulated in silica gel materials. Unfortunately, none of these spectroscopic techniques are able to provide insights about the detrimental causes affecting the viability of encapsulated cells. The current work uses cryo-scanning electron microscopy (cryo-SEM) for the in situ study of hydrated biocomposites, given its ability for mapping the water distribution within the host matrix. Cryo-SEM is accompanied by fluorescence experiments which allow correlating the metabolic activity of the cells with their structural integrity. The combination of these techniques provides useful information for the design of new biocomposites where encapsulated bacteria preserve their structural integrity and, thus, are viable fo...

Cryo-etch scanning electron microscopy (cryo-etch SEM) of aqueous gels composed of colloidal silica nanoparticles in the 1−40 nm range and liposomes of ∼200 nm gave unique morphologies. The aqueous...

Highly fluorescent Nile Red (NR) nanoparticles embedded in a hybrid sol-gel glass are reported. The crystallite growth within the confined system created by the porous hybrid matrix results in NR nanoparticles of averaged dimensions below 36 nm. The preparation process allows for the control of both the conformation adopted by single NR molecules prior to aggregation (e.g., near planar) and the configuration of the aggregates (e.g., oblique with phi < 54.7 degrees) prior to their assembly in the supramolecular architecture which ultimately forms the nanoparticles. The full preservation of the fluorescent configuration of the aggregates in the nanoparticles is confirmed through the application of the exciton theory, and it is responsible for the significant increase of the fluorescence emission intensity (e.g., up to 525- and 70-fold as compared to that obtained for single NR molecules embedded in pure and hybrid silica glasses, respectively).

The peroxidase activity of immobilized horseradish peroxidase (HRP) has been employed for the asymmetric oxidation of thioanisole in acetonitrile with H 2 O 2 (30%). Encapsulation of HRP by the sol–gel method considerably enhanced its operational stability by protecting the peroxidase activity under harsh conditions. The total rates of the encapsulated HRP increased up to six-fold (TTN=4.22×10 3 ) the rates observed with its homogeneous counterpart. The sulfoxide selectivity and the enantiomeric excess also increased greatly upon encapsulation. Coupling glucose oxidase reaction to the encapsulated peroxidase allowed high enantiomeric excesses (up to 56%) and sulfoxide as sole product by elimination of side non-enantioselective and overoxidation reactions. The heterogeneous catalyst can be recycled by simple filtration in successive runs.

An alcohol-free sol−gel route based on the controlled vacuum evaporation of the alcohol that results as a byproduct of the hydrolysis and condensation of alkoxyde precursors is described for the encapsulation of living bacteria. The ability of the encapsulated cells (a genetically engineered E. coli strain) to express a fluorescent protein in response to the presence of dicyclopropyl ketone has been used to study both the biocompatibility of the encapsulation route and the viability of the encapsulated cells with aging time. Thus, up to 95% of the integrity of the living cell along the encapsulation process has been preserved through alcohol removal of the starting sol. In addition, the use of organically modified rather than pure silica gels as the host matrix has shown a notable improvement in the viability of encapsulated cells (18 versus 6 days, respectively).

Rhodamine 19 (R19) doped silica glasses were prepared through the sol−gel process with dye concentrations ranging from 4.0 × 10-6 to 6.4 × 10-4 M. The role that the porous surface of the silica glasses plays on the R19 aggregation process was studied through excitation and emission fluorescence spectroscopy, absorption spectroscopy, and fluorescent lifetime measurements. The photophysical behavior of R19 at intermediate concentration values revealed the formation of fluorescent J-dimers in an in-plane oblique angle configuration. The exciton theory was used for the elucidation of the adsorption angle (φ), the angle between the monomer units (α), and the separation distance between the molecules (R) of the R19 fluorescent dimers. Further increase of R19 concentration was observed to promote the conversion from fluorescent to nonfluorescent dimers (H-dimers) through a rearrangement of the monomeric constituents to obtain a parallel plane twist angle configuration.

Fluorescence means (fluorescence spectroscopy, lifetime measurements, and fluorescence anisotropy) are used to study the extension in which sulforhodamine B (SB) is adsorbed on the internal surface of porous sol−gel silica glasses. The formation of fluorescent J-dimers as a consequence of the SB adsorption on the internal surface of the porous matrix is also studied for dye concentrations ranging from 4.0 × 10-6 to 3.2 × 10-4 M. It is observed that the configuration adopted by the fluorescent dimers and also the concentration value at which the fluorescent dimers become nonfluorescent dimers differ from those reported for rhodamine B (RB). Fluorescence anisotropy provide evidence of how the structural differences in the phenyl pending groups between both rhodamines govern the strength of the chemical interactions that SB and RB molecules establish with the surface and thus their capability of rearrangement on such a surface.

SiO2-TiO2 binary oxides are typically used as solid supports for different applications, from catalysts to optics. Tailoring the pore diameter, pore size distribution, and surface area is of great importance for any of those applications. Tailoring the chemical properties of the porous surface, e.g. in terms of polarity or acidity, is of capital importance as well. Thus, in catalytic applications or in sensing devices, where diffusion of a solute through the matrix is required, the affinity/compatibility of the solute with the matrix porous surface will determine the proper work of the device. Moreover, when the sensor is based on the adsorption of an active organic molecule or biomolecule on the porous surface matrix, the proton concentration at the surface may also modify the behavior of the active molecule. In this work, the proton affinity of the porous surface is tailored by the preparation of number of SiO2-TiO2 binary oxides with different SiO2/TiO2 weight ratios. Proton affinity is studied through the incorporation of a pH indicator as bromocresol green.

Tailoring of the chemical properties at the porous cage of the ormosils is being the objective of many works in the last years. One approach for the modification of such chemical properties is the incorporation of surfactants. In this work, ormosils (organically modified silicates) were prepared by the sol-gel process through the incorporation of cetyltrimethylammonium bromide (CTAB). Oxazine 1 (OX1) and Coumarine 153 (C153) were incorporated as fluorescent probes. The studied optical properties were absorption and fluorescence spectra, fluorescence lifetimes and fluorescence anisotropy. The combination of those measurements, achieved for two different dyes, provided a useful approach for the elucidation of the different environments that can be created at the porous cage of CTAB based ormosils; i.e. OX1 reported about a highly hydrated and polar environment, while C153 about a non-polar environment. It is noteworthy that the microviscosity calculated in both environments was higher than their analogous at a CTAB micelle in solution, which denotes an increase of the degree of ordering of the confined molecules most likely induced by the porous silica surface.

Sol-gel matrices have been shown to be relatively inert while preserving the spectroscopic properties and biological activity of the encapsulated proteins. Horseradish peroxidase (HRP) is a hemeprotein widely used in the field of biosensors because of its high specificity for hydrogen peroxide. However, partial inactivation of the protein has been reported when incorporated in aged gels. Whether that inactivation comes from the unfolding of some of the encapsulated proteins or from the leaching of the heme non-covalent active site of HRP is evaluated by absorption and fluorescence spectroscopy. This study shows that the single Trytophan (Trp) fluorescence of HRP may be used to distinguish denaturation processes from leaching of the heme group, as well as to estimate the extent of the denaturation.

The increasing prevalence and high sanitary costs of lesions affecting the central nervous system (CNS) at the spinal cord are encouraging experts in different fields to explore new avenues for neural repair. In this context, graphene and its derivatives are attracting significant attention, although their toxicity and performance in the CNS in vivo remains unclear. Here, the subacute tissue response to 3D flexible and porous scaffolds composed of partially reduced graphene oxide is investigated when implanted in the injured rat spinal cord. The interest of these structures as potentially useful platforms for CNS regeneration mainly relies on their mechanical compliance with neural tissues, adequate biocompatibility with neural cells in vitro and versatility to carry topographical and biological guidance cues. Early tissue responses are thoroughly investigated locally (spinal cord at C6 level) and in the major organs (i.e., kidney, liver, lung, and spleen). The absence of local and systemic toxic responses, along with the positive signs found at the lesion site (e.g., filler effect, soft interface for no additional scaring, preservation of cell populations at the perilesional area, presence of M2 macrophages), encourages further investigation of these materials as promising components of more efficient material-based platforms for CNS repair., This work was supported by the Instituto de Salud Carlos III (ISCIII) and Ministerio de Economía y Competitividad (MINECO) (Grant CP13/00060), co‐financed by FEDER funding, and MINECO (Grants MAT2011‐25329 and MAT2013‐43229‐R). AGM and MCS acknowledge ISCIII‐MINECO for respective contracts associated to project CP13/00060.

Superbases have shown high performance as catalysts in the chemical fixation of CO to epoxides. The proposed reaction mechanism typically assumes the formation of a superbase, the CO2 adduct as the intermediate, most likely because of the well-known affinity between superbases and CO, i.e., superbases have actually proven quite effective for CO absorption. In this latter use, concerns about the chemical stability upon successive absorption-desorption cycles also merits attention when using superbases as catalysts. In this work, H NMR spectroscopy was used to get further insights about (1) whether a superbase, the CO adduct, is formed as an intermediate and (2) the chemical stability of the catalyst after reaction. For this purpose, we proposed as a model system the chemical fixation of CO to epichlorohydrin (EP) using a deep eutectic solvent (DES) composed of a superbase, e.g., 2,3,4,6,7,8-hexahydro-1H-pyrimido[1,2-α]pyrimidine (TBD) or 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (DBU), as a hydrogen acceptor and an alcohol as a hydrogen bond donor, e.g., benzyl alcohol (BA), ethylene glycol (EG), and methyldiethanolamine (MDEA), as the catalyst. The resulting carbonate was obtained with yields above 90% and selectivities approaching 100% after only two hours of reaction in pseudo-mild reaction conditions, e.g., 1.2 bars and 100 °C, and after 20 h if the reaction conditions of choice were even milder, e.g., 1.2 bars and 50 °C. These results were in agreement with previous works using bifunctional catalytic systems composed of a superbase and a hydrogen bond donor (HBD) also reporting good yields and selectivities, thus confirming the suitability of our choice to perform this study., The authors acknowledge Spanish MINECO/FEDER (Grant MAT2015-68639-R) for financial support.

With global warming becoming one of the main problems our society is facing nowadays, there is an urgent demand to develop materials suitable for CO2 storage as well as for gas separation. Within this context, hierarchical porous structures are of great interest for in-flow applications because of the desirable combination of an extensive internal reactive surface along narrow nanopores with facile molecular transport through broad >highways> leading to and from these pores. Deep eutectic solvents (DESs) have been recently used in the synthesis of carbon monoliths exhibiting a bicontinuous porous structure composed of continuous macroporous channels and a continuous carbon network that contains a certain microporosity and provides considerable surface area. In this work, we have prepared two DESs for the preparation of two hierarchical carbon monoliths with different compositions (e.g., either nitrogen-doped or not) and structure. It is worth noting that DESs played a capital role in the synthesis of hierarchical carbon monoliths not only promoting the spinodal decomposition that governs the formation of the bicontinuous porous structure but also providing the precursors required to tailor the composition and the molecular sieve structure of the resulting carbons. We have studied the performance of these two carbons for CO2, N2, and CH4 adsorption in both monolithic and powdered form. We have also studied the selective adsorption of CO2 versus CH4 in equilibrium and dynamic conditions. We found that these materials combined a high CO2-sorption capacity besides an excellent CO2/N2 and CO2/CH4 selectivity and, interestingly, this performance was preserved when processed in both monolithic and powdered form., This work was supported by MINECO—with grants MAT2012-34811 and MAT2011-25329 (from the National Program of Fundamental Research), PLE2009-0052 (from the Strategic Japanese-Spanish Cooperation Program), and PCIN-2013-057 (from the Concert Project-NASEMS)—and by Generalitat Valenciana, Grant PROMETEO/2009/002. N.L.S. also acknowledges MINECO for an FPI contract. E.O.J. thanks the CNPq−Brazil for her grant.

Tailoring of the chemical properties at the porous cage of silica matrixes is the objective of many works in the last years, since it determines the different allocation of dopants and thus its future reactivity and functionality. One approach for the modification of such chemical properties is the incorporation of surfactants. Ormosils (organically modified silicates) can be prepared by the sol−gel process through the incorporation of cetyltrimethylammonium bromide (CTAB). The study of the fluorescent properties of coumarin 153 (C153), which is also incorporated, will provide information of the environment surrounding the probe within the porosity of the ormosils. The fluorescent study of C153-doped ormosils was based on the following fluorescence measurements: (a) absorption, excitation, and emission spectra, (b) fluorescence lifetimes, and (c) anisotropy. Time-resolved anisotropy will provide a quantitative determination of the different microviscosity values that can be found within the porosity of g...

Rhodamine 101 (R101) doped silica gels were prepared through the sol−gel process with dye concentrations ranging from 4.0 × 10-6 to 6.4 × 10-4 M. Excitation and emission fluorescence spectra and lifetime measurements were recorded for R101 doped silica gels in the whole range of concentrations. The photophysical behavior of the gel-glasses doped with high concentrations of R101 resembles that of fluorescent J-dimers in a coplanar inclined configuration. The formation of fluorescent J-dimers in a coplanar inclined rather than in an oblique configuration is discussed in terms of the molecular structure of R101.

Ormosils (organically modified silicates) were prepared by the sol–gel process through the incorporation of non-ionic surfactants in the starting solution. Oxazine 1 was used as the fluorescent probe for the achievement of this study. Thus, recording of the absorption and emission fluorescence spectra, as well as measurement of the fluorescence lifetimes of oxazine 1, enabled us to determine the allocation of organic molecules within the porosity of silica gel-glasses. Furthermore, the reorientational correlation times of the fluorescent probe have been obtained through fluorescence anisotropy. According to the microviscosity data calculated from the fluorescent anisotropy measurements, movement of oxazine 1 is more restricted in the porous cage of ormosils than it is in silica gel-glasses.

The present work explores the enzymatic driven biomineralization of a model silica substrate. Jack Bean Urease was covalently anchored onto synthetic aminopropyl-capped silica spheres. After several hours of aging at physiological temperatures in the presence of urea, Ca(II) and phosphate ions, homogeneous nanoparticulated hydroxyapatite-like shells were obtained. Fil: Ortega, Ilida. Consejo Superior de Investigaciones Científicas; España. Instituto de Ciencia de Materiales de Madrid; España Fil: Jobbagy, Matias. Consejo Superior de Investigaciones Científicas; España. Instituto de Ciencia de Materiales de Madrid; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Centro de Investigación en Nanociencia y Nanotecnología (CIN2); España Fil: Ferrer, María Luisa. Instituto de Ciencia de Materiales de Madrid; España Fil: del Monte, Francisco. Instituto de Ciencia de Materiales de Madrid; España

Nanocomposites of amorphous calcium phosphate (ACP) nanoparticles embedded within chitosan (CHI) have been prepared through an enzymatically assisted route. Cryogenic processing (ISISA) of hydrogel nanocomposites has allowed for the achievement of hierarchical materials (e.g., microchannelled structured ACP/CHI nanocomposites). Fil: Gutierrez, María C.. Instituto de Ciencia de Materiales de Madrid; España Fil: Jobbagy, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Ciencia de Materiales de Madrid; España Fil: Ferrer, María L.. Instituto de Ciencia de Materiales de Madrid; España Fil: del Monte, Francisco. Instituto de Ciencia de Materiales de Madrid; España

Nervous tissue lesions are an important social concern due to their increasing prevalence and their high sanitary costs. Their treatment still remains a challenge because of the reduced ability of nervous tissue to regenerate, its intrinsic structural and functional complexity and the rapid formation of fibroglial scars inhibiting neural repair. Herein, we show that 3D porous scaffolds made of chondroitin sulphate (CS), a major regulatory component of the nervous tissue, and multi-walled carbon nanotubes (MWCNTs) are selective substrates for the formation of a viable and neuron-enriched network with a transitory low glial content. Scaffolds have been fabricated by using the ice segregation-induced self-assembly technique and cultured with embryonic neural progenitor cells. Cell adhesion, morphology, viability, neuron/glial differentiation, calcium signaling dynamics, and mitochondrial activity have been studied over time on the scaffolds and compared to appropriate 2D control substrates. Our results indicate the formation of viable cultures enriched in neuron cells for up to 20 days, with ability to display calcium transients and active mitochondria, even in the absence of poly-d-lysine coating. A synergistic neural-permissive signaling from both the scaffold structure and its components (i.e., MWCNTs and CS) is suggested as the major responsible factor for these findings. We anticipate that these scaffolds may serve nerve regeneration if implanted in the acute phase after injury, as it is during the first stages of graft implantation when the most critical sequence of phenomena takes place to drive either nervous regeneration or fibroglial scar formation. The temporary glial inhibition found may be, indeed, beneficial for promoting the formation of neuron-enriched circuits at early phases while guaranteeing posterior glial integration to support longer-term neuron survival and activity. © 2013 Elsevier Ltd., This work was supported by MINECO (projects MAT2009-10214, MAT2011-25329 and MAT2012-34811). M.C.S. is greatly in debt with MINECO for a Juan de la Cierva fellowship. S.N. acknowledges CSIC for a JAE-Pre fellowship.

Deep eutectic solvents (DESs) composed of resorcinol, 3-hydroxypyridine and tetraethylammonium bromide were used for the synthesis of hierarchical nitrogen-doped carbon molecular sieves. DESs played multiple roles in the synthetic process, as the liquid medium that ensures reagent homogenization, the structure-directing agent responsible for the achievement of the hierarchical structure, and the source of carbon and nitrogen for the solid sorbent obtained after carbonization. Thus, the synthesis offers an economy of reagents that emphasizes the green nature and low cost of conventional polycondensation. Interestingly, while macropores facilitated mass transport and access to the surface area, the combination of the molecular sieve structure and nitrogen functionalization provided, respectively, excellent CO2 adsorption capacities of up to 3.7 mmol g-1, and outstanding CO 2-N2 selectivities of up to 14.4 from single component gas data. Nonetheless, the CO2-N2 selectivity in the Henry law regime-representative of post-combustion flue-gas streams-of some of our carbons was particularly remarkable (e.g. 96), comparable to or even higher than those described for most recent carbons, and only surpassed by those of certain zeolites. This journal is © the Partner Organisations 2014., This work was supported by MINECO (MAT2009-10214, MAT2011-25329, CTM2011-23378, and MAT2012-34811). DC thanks CSIC for a JAE-Doc postdoctoral contract co-funded by the European Social Fund. JP thanks MINECO for a FPI fellowship.

Chitosan is the N-deacetylated derivative of chitin, a naturally abundant mucopolysaccharide that consists of 2-acetamido-2-deoxy-β-D-glucose through a β (1→4) linkage and is found in nature as the supporting material of crustaceans, insects, etc. Chitosan has been strongly recommended as a suitable functional material because of its excellent biocompatibility, biodegradability, non-toxicity, and adsorption properties. Boosting all these excellent properties to obtain unprecedented performances requires the core competences of materials chemists to design and develop novel processing strategies that ultimately allow tailoring the structure and/or the composition of the resulting chitosan-based materials. For instance, the preparation of macroporous materials is challenging in catalysis, biocatalysis and biomedicine, because the resulting materials will offer a desirable combination of high internal reactive surface area and straightforward molecular transport through broad >highways> leading to such a surface. Moreover, chitosan-based composites made of two or more distinct components will produce structural or functional properties not present in materials composed of one single component. Our group has been working lately on cryogenic processes based on the unidirectional freezing of water slurries and/or hydrogels, the subsequent freeze-drying of which produce macroporous materials with a well-patterned structure. We have applied this process to different gels and colloidal suspensions of inorganic, organic, and hybrid materials. In this review, we will describe the application of the process to chitosan solutions and gels typically containing a second component (e.g., metal and ceramic nanoparticles, or carbon nanotubes) for the formation of chitosan nanocomposites with a macroporous structure. We will also discuss the role played by this tailored composition and structure in the ultimate performance of these materials., This work was supported by MINECO (MAT2009-10214 and MAT2012-34811). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

This is an open-access article distributed under the terms of the Creative Commons Attribution License., Numerous strategies that are currently used to regenerate bone depend on employing biocompatible materials exhibiting a scaffold structure. These scaffolds can be manufactured containing particular active compounds, such as hydroxyapatite precursors and/or different growth factors to enhance bone regeneration process. Herein, we have immobilized calcium phosphate salts (CPS) and bone morphogenetic protein 2 (BMP-2) - combined or alone - into chitosan scaffolds using ISISA process. We have analyzed whether the immobilized bone morphogenetic protein preserved its osteoinductive capability after manufacturing process as well as BMP-2 in vitro release kinetic. We have also studied both the in vitro and in vivo biocompatibility of the resulting scaffolds using a rabbit model. Results indicated that rhBMP-2 remained active in the scaffolds after the manufacturing process and that its release kinetic was different depending on the presence of CPS. In vitro and in vivo findings showed that cells grew more in scaffolds with both CPS and rhBMP-2 and that these scaffolds induced more bone formation in rabbit tibia. Thus chitosan scaffolds containing both CPS and rhBMP-2 were more osteoinductive than their counterparts alone indicating that could be useful for bone regeneration purposes, such as some applications in dentistry. Copyright: © 2014 Guzmán et al., This work was supported by Spanish Ministry of Economy and Competitiveness (MINECO) (CONSOLIDER project CSD2009-00088), Ministerio de Ciencia e Innovación (MAT2009-10214, MAT2011-25329, MAT2012-34811, SAF2011-27863) and Seventh Framework Programme of the European Commission (EuroNanomed ERA-NET initiative, REBONE project; PI10/02985FIS).

Carbon nanotubes (CNTs) have lately attracted significant attention in the field of biomedicine. Although a wide repertoire of CNT-based composites has been explored as substrates for cell growth, the fabrication of 3D scaffolds has been more rarely accomplished. Additionally, concerns referred to CNT biocompatibility make their use in biomaterials still controversial. Herein we explore the interaction of three types of CNT-based 3D scaffolds – prepared with multi-walled CNTs and processed to show different architectural and morphological features at the microscale by using three different polymers (i.e., chitosan, chondroitin sulphate and gelatin) – with three types of mammalian cells displaying different sizes and adhesion patterns. Cell–material interaction has been assessed by studying cell viability, adhesion, morphology, and apoptosis. By means of time-lapse confocal laser scanning microscopy, we investigate, for the first time in CNT-based scaffolds, cell migration processes in real time. Scaffolds displaying both a pore size in range with that of cells and lower surface roughness reveal the highest viability values. In contrast, those with a smaller pore size and higher surface roughness account for the lowest cytocompatibility. Results from these studies benefit the fabrication of optimized biomaterials by varying scaffold-dependent parameters in accordance with those of target cells. Furthermore, they may serve to anticipate the response of other cell types sharing similar characteristics to those described herein when in contact with CNT-based scaffolds., This work was supported by MINECO (projects MAT2009-10214, MAT2011-25329, PIE 201060I017, and MAT2012-34811) and from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement number 263289 (Green Nano Mesh). S.N. acknowledges CSIC for a JAE-Pre fellowship. M.C.S. is greatly in debt with MINECO for a Juan de la Cierva fellowship.

The aim of this review is to provide an exposition of some of the most recent applications of deep-eutectic solvents (DESs) in the synthesis of polymers and related materials. We consider that there is plenty of room for the development of fundamental research in the field of DESs because their compositional flexibility makes the number of DESs susceptible of preparation unlimited and so do the range of properties that DESs can attain. Ultimately, these properties can be transferred into the resulting materials in terms of both tailored morphologies and compositions. Thus, interesting applications can be easily envisaged, especially in those fields in which the preparation of high-tech products via low cost processes is critical. We hope that the preliminary work surveyed in this review will encourage scientists to explore the promising perspectives offered by DESs.

The aim of this review is to provide an exposition of some of the most recent applications of deep-eutectic solvents (DESs) in the synthesis of polymers and related materials. We consider that there is plenty of room for the development of fundamental research in the field of DESs because their compositional flexibility makes the number of DESs susceptible of preparation unlimited and so do the range of properties that DESs can attain. Ultimately, these properties can be transferred into the resulting materials in terms of both tailored morphologies and compositions. Thus, interesting applications can be easily envisaged, especially in those fields in which the preparation of high-tech products via low cost processes is critical. We hope that the preliminary work surveyed in this review will encourage scientists to explore the promising perspectives offered by DESs.

This work presents a novel and simple aqueous sol−gel route for the encapsulation of biomolecules, which are labile to the alcohol that results as a byproduct of the matrix formation. The controlled vacuum evaporation of the alcohol by rotavapor methods provides an aqueous sol in which the activity of labile biomolecules is preserved. The versatility of this approach is remarkable since it allows the preparation of pure silica matrixes as well as ormosils.

WOS: 000264524200020, This work describes the preparation of microchannel structured monolithic pieces by the "ice-segregation induced self-assembly'' (ISISA) process. The monoliths exhibit a hierarchical structure composed of homogeneously mixed colloidal silica resulting from hydrolysis and condensation of an alkoxysilane precursor (e. g., TEOS) and TiO2 polycrystalline nanoparticles adsorbed onto sepiolite fibres. The combination of such a different species into a single macroporous structure provides a multifunctional material capable of water decontamination by pollutant removal from aqueous media (via adsorption on sepiolite) and subsequent elimination by UV irradiation (via photocatalytic oxidation on TiO2 nanoparticles). The performance of the resulting materials has been studied using two organic compounds often present in wastewater such as p-nitrophenol (PNP) and methylene blue (MB)., MEC [MAT2006- 02394, S- 0505/ PPQ- 0316]; CSIC [200760I009, 200660F01], This work was supported by MEC (MAT2006- 02394 Project), CM (S- 0505/ PPQ- 0316 Project) and CSIC (200760I009 and 200660F01 Projects). M. N.- S. acknowledges TPA and CSIC for an I3P postdoctoral research contract. M. C. G. acknowledges MICINN for an R& C research contract.