Search

[EN] Knitted iron phthalocyanine-based porous polymer networks (K-FePcs) were prepared in a single step using solvent-knitting strategies with commercial iron phthalocyanine as a building monomer. The incorporation of different aryl comonomers (biphenyl and 1,2,4,5-tetraphenylbenzene) to FePc allowed quantitative yields, high porosities, and excellent ORR activity. The reversible Fe(III)/Fe(II) redox potential of FeN4 centers of the knitted polymer networks in N2-saturated electrolyte solution (i.e., ∼0.8 V vs RHE) were shown as good descriptors of their ORR activity. K-FePc2Ph presented the highest amount of FeN4 active sites and an adequate degree of steric hindrance to maintain the isolation between catalytically active sites. Moreover, it displayed comparable current density limits and superior mass activity and half-wave potential (i.e., 0.88 V vs RHE) than those of 20% Pt/C benchmark catalyst, while keeping higher stability toward methanol oxidation. K-FePc2Ph can be an interesting alternative to Pt-based ORR electrocatalysts.

Vortex ring (VR) processes have proved highly effective in tailoring the morphology/shape of particles prepared from nanoclays, silica nanocolloids, magnetic nanoparticles and different polysaccharides. Herein, we have prepared toroidal-, teardrop-, jellyfish-, and cap-shaped vortex ring particles by drip- ping an aqueous suspension of graphene oxide (GO) into a cetyl trimethylammonium bromide (CTAB) aqueous solution that played the role of coagulating agent. Interestingly, the GO suspension exhibited liquid crystalline features. We demonstrated how controlling the drop impact force against the liquid surface was critical to produce VR particles with such intriguing shapes. With the purpose of controlling the drop impact force, we studied the drop density/viscosity, the speed at which the drop impacts the surface of the liquid pool and the surface tension of the CTAB solution. Finally, we also demonstrated the antibacterial activity of the resulting GO-based VR particles against Escherichia coli and Bacillus subtilis, and discussed about the origin of such a behaviour. In particular, we investigated the occurrence of (1) membrane damage by physical contact between GO and bacteria, (2) GO-induced oxidative stress, or (3) CTAB released into the bacteria culture, the antiseptic and disinfectant action of which may ultimately kill bacteria.

[EN] In the present contribution, we report how through the use of metal-organic frameworks (MOFs) composed of addressable combinations of up to four different metal elements it is possible to program the composition of multimetal oxides, which are not attainable by other synthetic methodologies. Thus, due to the ability to distribute multiple metal cations at specific locations in the MOF secondary building units it is possible to code and transfer selected metal ratios to multimetal oxides with novel, desired compositions through a simple calcination process. The demonstration of an enhancement in the electrocatalytic activity of new oxides by preadjusting the metal ratios is here reported for the oxygen reduction reaction, for which activity values comparable to commercial Pt/C catalysts are reached, while showing long stability and methanol tolerance.

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.

Porous carbons are really interesting materials for applications such as gas adsorption, electrocatalysts or energy harvesting and conversion.[1] Among others, spinodal decomposition (SD) processes have proved effective for the synthesis of macro- and mesoporous materials.[2] Despite the theoretical aspects of SD processes are well understood, finding the proper experimental conditions to obtain bicontinuous structures via SD processes is a non-predictable and quite tedious process, typically based on trial and error. The challenge is therefore finding a ¿tool¿ capable to predict the suitability of a particular starting solution to undergo a spinodal decomposition process. We have used aqueous solutions of different DESs containing common carbon precursors (i. e. resorcinol) for the preparation of bicontinuous porous carbons via polycondensation of resorcinol with formaldehyde. Scanning electron microscopy analysis of the different carbons allowed us to determine which solutions leads to bicontinuous structures via SD. Moreover, we studied the starting DES/H2O binary mixtures by Brillouin spectroscopy given the capability of this technique to observe local structure rearrangements resulting from non-ideal mixing of the components. In our case, we found that the representation of data obtained by Brillouin spectroscopy allows predicting the range of molar fractions of DES in H2O for which bicontinuous structures via SD are ultimately obtained.

Neural tissue engineering approaches show increasing promise for the treatment of neural diseases including spinal cord injury, for which an efficient therapy is still missing. Encouraged by both positive findings on the interaction of carbon nanomaterials such as graphene with neural components and the necessity of more efficient guidance structures for neural repair, we herein study the potential of reduced graphene oxide (rGO) microfibers as substrates for neural growth in the injured central neural tissue. Compact, bendable, and conductive fibers are obtained. When coated with neural adhesive molecules (poly-L-lysine and N-cadherin), these microfibers behave as supportive substrates of highly interconnected cultures composed of neurons and glial cells for up to 21 days. Synaptic contacts close to rGO are identified. Interestingly, the colonization by meningeal fibroblasts is dramatically hindered by N-cadherin coating. Finally, in vivo studies reveal the feasible implantation of these rGO microfibers as a guidance platform in the injured rat spinal cord, without evident signs of subacute local toxicity. These positive findings boost further investigation at longer implantation times to prove the utility of these substrates as components of advanced therapies for enhancing repair in the damaged central neural tissue including the injured spinal cord.

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.

Spinodal decomposition (SD) processes have proved effective for the synthesis of macro- and mesoporous materials. Despite the theoretical aspects of SD processes are well understood, finding the proper experimental conditions – both the components as well as the ratio in which they have to be combined – to attain co-continuous structures is a non-predictable and quite tedious process, typically based on trial and error. The challenge is finding a “tool” capable to predict the suitability of a particular starting solution to undergo SD processes. Here in, we used aqueous solutions of deep eutectic solvents (DESs) for the preparation via SD of co-continuous porous carbons, the morphologies of which ranged from spinodal to aggregates-of-particles-like just depending on dilution. Despite the starting DES/HO binary mixture was macroscopically homogeneous, Brillouin spectroscopy revealed the occurrence of certain nanostructural rearrangements within a dilution range that coincided with that used for preparation of carbons with morphologies transitioning from spinodal to aggregates-of-particles-like. Moreover, carbons exhibited a noticeable degree of heteroatom co-doping – e.g. N and P – and proved particularly effective for CO capture with adsorptions of up to 4.7 mmol/g at 0 °C and 760 mbar.

Eutectic mixtures of the monohydrated form of p-toluenesulfonic acid (pTsOH·HO) and triethyl phosphate (TEP) in a 1: 1 molar ratio were used as the medium to disperse previously functionalized multiwalled carbon nanotubes (MWCNTs), and to catalyse the polycondensation of furfuryl alcohol. Hierarchically structured P-doped carbon-CNT composites were obtained after carbonization. The high surface area, the phosphate functionalization, the hierarchical structure and the good electrical conductivity exhibited by these composites provided remarkable metrics when they were used as electrodes in a supercapacitor cell, with energy densities of around 22.6 W h kg and power densities of up to 10 kW kg for operational voltages of up to 1.5 V. This performance surpasses any performance previously reported for electrodes weighing (at least) 10 mg per cm of current collector and using an aqueous electrolyte. Actually, the supercapacitor cell built up with these electrodes provided enough neat energy to turn an IR LED of 30 mW on and emit light over a certain period.

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.

Deep eutectic solvents (DESs) composed of resorcinol, either 2-cyanophenol or 4-cyanophenol, and choline chloride were used for the synthesis of hierarchical nitrogen-doped carbon molecular sieves. Carbons were obtained with high conversions by polycondensation of resorcinol and either 2-cyanophenol or 4-cyanophenol with formaldehyde, and subsequent carbonization at 800 °C in nitrogen atmosphere. The nitrogen content was ca. 2.4 wt%, revealing an excellent nitrogen-doping efficiency for cyanophenol derivatives when used in the form of DES. The use of either 2-cyanophenol or 4-cyanophenol modified the contribution of quaternary-Nvalley groups in the resulting carbons, being larger in carbons coming from 4-cyanophenol than in those coming from 2-cyanophenol. The hierarchical porous structure was composed of micro-, meso- and macropores, and the diameter distribution of mesopores was also related to the use of either 2-cyanophenol or 4-cyanophenol. These structural and compositional differences were critical for the use of the resulting hierarchical nitrogen-doped carbons as efficient metal-free electrocatalysts. In particular, the carbons coming 4-cyanophenol proved particularly effective in the direct reduction of oxygen to OH− (H2O in acidic solution) through a four-electron (4e−) process with high catalytic activity and selectivity, and longer stability and stronger tolerance to crossover effects than platinum-based electrocatalysts.

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.

Liquid marbles (LMs) are nonsticky droplets covered by micro- or nanometrically scaled particles and obtained by simply rolling small amounts of a liquid in a very hydrophobic powder. Since pioneer work by Aussillous and Quéré, a wide palette of hydrophobic materials for the preparation of LMs, as well as potential applications, have been reported. Because of the bioinspired origin of this concept, the applicability of LMs in biomedicine is gaining increasing attention, with remarkable advances in their use as microbioreactors for blood typing, drug screening, and tumor growth, among others. Herein, we explore the novel use of LMs as a biotechnological tool for the cryopreservation of mammalian cells as an alternative to conventional methods, which typically require the use of cryopreservant agents that commonly associate with some degree of cell toxicity. Murine L929 fibroblasts, a reference cell line for cytotoxicity studies, and poly(tetrafluoroethylene), a hydrophobic polymer widely used in cardiovascular surgery, were selected for the preparation of the cell-containing LMs. Our results reveal that there is a safe range of droplet volumes and cell densities that can be successfully used to cryopreserve mammalian cell lines and recover them after thawing without significantly affecting major cellular parameters such as adhesion, morphology, viability, proliferation, and cell cycle. We envision that progress in the exploration of cell-containing LMs could also open their impact as microreactors for the miniaturization of cytotoxicity procedures of drugs and materials in which powerful tools for cell evaluation such as flow cytometry could be used because of the elevated amount of cells handled.

A template‐free approach based on the use of eutectic mixtures composed of 2‐hydroxymethylthiophene and furfuryl alcohol has been designed for the preparation of hierarchical sulfur‐doped carbons (SPCs) in monolithic form. The temperature used for carbonization, for example, 600, 800, or 900 °C, determined most of the physicochemical properties of the resulting SPCs. Thus, the surface area increased from below 400 to up 775 m2 g−1, along with the carbonization temperature, whereas the sulfur content decreased from approximately 15 to 5 wt %. The oxygen reduction reaction performance in samples carbonized at 900 °C was good, with the four‐electron‐transfer reaction prevailing over the two‐electron‐transfer one. Interestingly, the methanol tolerance and stability of these SPCs were also remarkable, with less than 5 % current decrease immediately after methanol addition, whereas, in terms of stability, the current decrease was below 8 % after 20000 s. This performance was in the range of that found not only for other SPCs, but also for many nitrogen‐doped and even some dual‐doped (S and N) ones.

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.

Since the seminal work by Pekala in 1989, polycondensation of phenol derivatives with formaldehyde and subsequent carbonization has been one of the most used procedures for preparation of porous carbons. Nitrogen-doped carbons have also been obtained through this approach only by using nitrogen-rich precursors. The list of the most commonly used nitrogen-rich precursors includes melamine, urea, 3-hydroxypyridine, 3-aminophenol and lysine, and despite a few of them can be used in a single fashion, they typically need to be co-condensed with a second precursor. Nitrogen-rich precursors different from these ones have been used rarely because their molecular structure does not favor the nucleophilic substitution through which polycondensation takes place-e.g. p-nitrophenol. This is by no means a trivial issue because, on the one hand, these precursors cannot form a cross-linked network by themselves, and on the other hand, it may be difficult to encompass their different reaction kinetics when combined with more reactive precursors. This is also the situation for other precursors with an amphiphilic molecular structure that could be of interest to control the structure of the resulting porous carbons-e.g. 4-hexylresorcinol. In this work, we have used deep eutectic solvents composed of resorcinol, 4-hexylresorcinol, p-nitrophenol and choline chloride for the preparation of nitrogen-doped carbon monoliths with a hierarchical porous structure. Carbon conversions ranged from 64 to 50%-depending on the carbonization temperature-despite using three different carbon precursors for co-condensation and two of them were uncommon. The nitrogen content ranged from 4.9 to 3.0 wt%, revealing an excellent nitrogen-doping efficiency for p-nitrophenol when used in the form of DES. Finally, the use of 4-hexylresorcinol controlled the formation of a narrow microporosity that, in combination with the nitrogen functionalities, provided a remarkable CO2-sorption capability to the resulting c

The absence of efficient therapies for the treatment of lesions affecting the central nervous system encourages scientists to explore new materials in an attempt to enhance neural tissue regeneration while preventing inhibitory fibroglial scars. In recent years, the superlative properties of graphene-based materials have provided a strong incentive for their application in biomedicine. Nonetheless, a few attempts to date have envisioned the use of graphene for the fabrication of three-dimensional (3D) substrates for neural repair, but none of these involve graphene oxide (GOx) despite some attractive features such as higher hydrophilicity and versatility of functionalization. In this paper, we report novel, free-standing, porous and flexible 3D GOx-based scaffolds, produced by the biocompatible freeze-casting procedure named ISISA, with potential utility in neural tissue regeneration. The resulting materials were thoroughly characterized by Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopies and scanning electron microscopy, as well as flexibility testing. Embryonic neural progenitor cells were then used to investigate adhesion, morphology, viability, and neuronal/glial differentiation. Highly viable and interconnected neural networks were formed on these 3D scaffolds, containing both neurons and glial cells and rich in dendrites, axons and synaptic connections, and the results are in agreement with those obtained in initial studies performed with two-dimensional GOx films. These results encourage further investigation in vivo on the use of these scaffolds as guide substrates to promote the repair of neural injuries.

The use of deep eutectic solvents (DESs) that act as all-in-one solvent-template-reactant systems offers an interesting green alternative to conventional syntheses in materials science. This Review aims to provide a comprehensive overview to emphasize the similarities and discrepancies between DES-assisted and conventional syntheses and rationalize certain green features that are common for the three DES-assisted syntheses described herein: one case of radical polymerization and two cases of polycondensations. For instance, DESs contain the precursor itself and some additional components that either provide certain functionality (e.g., drug delivery and controlled release, or electrical conductivity) to the resulting materials or direct their formation with a particular structure (e.g., hierarchical-type). Moreover, DESs provide a reaction medium, so polymerizations are ultimately carried out in a solventless fashion. This means that DES-assisted syntheses match green chemistry principles 2 and 5 because of the economy of reagents and solvents, whereas the functionality incorporated by the second component allows the need for any post-synthesis derivatization to be minimized or even fully avoided (principle 8). DESs also provide new precursors that favor more efficient polymerization (principle 6) by decreasing the energy input required for reaction progress. Finally, the use of mild reaction conditions in combination with the compositional versatility of DESs, which allows low-toxic components to be selected, is also of interest from the viewpoint of green chemistry because it opens up the way to design biocompatible and/or eco-friendly synthetic methods (principle 3). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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.

Carbon nanotubes and graphene are some of the most intensively explored carbon allotropes in materials science. This interest mainly resides in their unique properties with electrical conductivities as high as 104 S cm-1, thermal conductivities as high as 5000 W m-1 K and superior mechanical properties with elastic moduli on the order of 1 TPa for both of them. The possibility to translate the individual properties of these monodimensional (e.g. carbon nanotubes) and bidimensional (e.g. graphene) building units into two-dimensional free-standing thick and thin films has paved the way for using these allotropes in a number of applications (including photocatalysis, electrochemistry, electronics and optoelectronics, among others) as well as for the preparation of biological and chemical sensors. More recently and while recognizing the tremendous interest of these two-dimensional structures, researchers are noticing that the performance of certain devices can experience a significant enhancement by the use of three-dimensional architectures and/or aerogels because of the increase of active material per projected area. This is obviously the case as long as the nanometre-sized building units remain accessible so that the concept of hierarchical three-dimensional organization is critical to guarantee the mass transport and, as consequence, performance enhancement. Thus, this review aims to describe the different synthetic processes used for preparation of these three-dimensional architectures and/or aerogels containing either any or both allotropes, and the different fields of application in which the particular structure of these materials provided a significant enhancement in the efficacy as compared to their two-dimensional analogues or even opened the path to novel applications. The unprecedented compilation of information from both CNT- and graphene-based three-dimensional architectures and/or aerogels in a single revision is also of interest because it allows a stra

The stability of hen's egg white lysozyme in different choline chloride-based pseudo-concentrated and neat deep eutectic solvents (DESs) has been studied by means of intrinsic fluorescence and CD spectroscopy. Thermal unfolding experiments carried out in non-diluted urea:choline chloride and glycerol:choline chloride eutectic solvents (UCCl-DES and GCCl-DES, respectively) showed the accumulation at certain temperatures of discrete, partially folded intermediates that displayed a high content of secondary structure and a disrupted tertiary structure. Reversibility of the unfolding process was incomplete in these circumstances, with the urea-based DES showing higher protein structure destabilization upon thermal treatment. On the other hand, aqueous dilution of the eutectic mixtures allowed the recovery of a reversible, two-state denaturation process. Lysozyme activity was also affected in neat and pseudo-concentrated GCCl-DES, with an increasing recovery of activity upon aqueous dilution, and full restoration after DES removal through extensive dialysis. These results suggest that protein interactions at room temperature are reversible and depend on the DES components and on the aqueous content of the original DES dilution. © 2013 the Owner Societies.

Deep Eutectic Solvents (DESs) formed between Acrylic Acid (AA) and Choline Chloride (CCl) exhibit certain properties of ionic liquids (e.g. high viscosity) that make them suitable for frontal polymerization (FP). The use of DESs not only as a monomer but also as the solvent prevents the use of additional solvents (i.e. typically of organic nature) and offers a green tool for the synthesis of functional composites. We have recently explored this approach for the preparation of poly(acrylic acid) (PAA) and poly(methacrylic acid). In this work, we have taken advantage of the outstanding capability of DESs to solubilize and/or disperse a number of substances to incorporate-in a homogeneous fashion-carbon nanotubes (in this particular case, N-doped MWCNT-CNxMWCNTs) in the polymerizable DES. Interestingly, CNxMWCNTs also played the role of an inert filler in FP. The resulting PAA-CNxMWCNT composites exhibited some distinct features as compared to previous PAA also obtained via DES-assisted FP. For instance, PAA-CNxMWCNT composites can undergo swelling depending on the pH, as bare PAA. However, the presence of CNxMWCNTs allows the formation of a macroporous structure after submission to a freeze-drying process, the achievement of which was not possible in bare PAA. The combination of structural (e.g. macroporosity) and functional (e.g. stimuli responsive) properties exhibited by these materials besides an eventually high biocompatibility-coming from the green character of the DES-assisted synthesis-should make the resulting macroporous PAA-CNxMWCNT composites excellent candidates for their future application as biomaterials. © 2013 The Royal Society of Chemistry.