Search

Microwave irradiation combined with mild heating was demonstrated as a suitable synthetic method for the preparation of NiCo2O4 nanowires and NiCo2O4-graphene oxide nanocomposites. In both cases, the synthesis was carried out in just a few minutes, at relatively low temperatures and with a certain economy of reagents. In the particular case of the nanocomposites, NiCo2O4 was deposited in form of not only nanowires, but also ultrafine nanoparticles on the surface of graphene oxide sheets due to the preferred activation of these sheets under microwave irradiation. The nanocomposites exhibited a superior performance to NiCo 2O4 nanowires as electrodes in pseudocapacitors with capacitance retentions of nearly 735 F g-1 at current densities of up to 33 A g-1. © 2013 The Royal Society of Chemistry.

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.

Bacterial infection related to the implantation of medical devices represents a serious clinical complication, with dramatic consequences for many patients. In past decades, numerous attempts have been made to develop materials with antibacterial and/or antifouling properties by the incorporation of antibiotic and/or antiseptic compounds. In this context, deep eutectic solvents (DESs) are acquiring increasing interest not only as efficient carriers of active principle ingredients (APIs) but also as assistant platforms for the synthesis of a wide repertoire of polymer-related materials. Herein, we have successfully prepared biodegradable poly(octanediol-co-citrate) polyesters with acquired antibacterial properties by the DES-assisted incorporation of quaternary ammonium or phosphonium salts into the polymer network. In the resulting polymers, the presence of these salts (i.e., choline chloride, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and methyltriphenylphosphonium bromide) inhibits bacterial growth in the early postimplantation steps, as tested in cultures of Escherichia coli on solid agar plates. Later, positive polymer cytocompatibility is expected to support cell colonization, as anticipated from in vitro preliminary studies with L929 fibroblasts. Finally, the attractive elastic properties of these polyesters permit matching those of soft tissues such as skin. For all of these reasons, we envisage the utility of some of these antibacterial, biocompatible, and biodegradable polyesters as potential candidates for the preparation of antimicrobial wound dressings. These results further emphasize the enormous versatility of DES-assisted synthesis for the incorporation, in the synthesis step, of a wide palette of APIs into polymeric networks suitable for biomedical applications. © 2013 American Chemical Society.

The deep eutectic solvents (DESs) based on the mixtures of a variety of ammonium salts and hydrogen bond donors containing acrylic acids and acrylamides are capable of sustaining frontal polymerization (FP). The selection of ammonium salt affects the reactivity and allows FP at relatively low temperature but with full conversion. Also, full conversion allows us to use these polymers for biomedical applications (e.g., drug delivery systems) as the unreactive ammonium salts can be released from the resulting polymer without by-products. We call these components >active fillers,> which can be ammonium salts with biological or pharmaceutical importance. For instance, we prepared poly(acrylic acid) loaded with lidocaine hydrochloride (a common anesthetic), the release of which was found to occur in a controlled fashion. The ammonium salts also create a sufficiently high viscosity to suppress buoyancy-driven convection without additional materials. The DES here described played an all-in-one role, providing the monomer, the active filler, and the polymerization medium for FPs. © 2013 Wiley Periodicals, Inc.

Hierarchically structured graphitic carbons synthesized from deep eutectic solvents exhibit a bicontinuous structure where the continuity of the graphitic domains throughout the entire 3D carbon network provides electrical conductivities of up to 31 S/cm to the depicted monoliths. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic liquids and deep eutectic solvents (a new class of ionic liquids obtained by complexation of quaternary ammonium salts with hydrogen bond donors such as acids, amines, and alcohols among others) have been recently used as solvents and even as precursors in the synthesis of carbonaceous materials. The use of long-alkyl-chain derivatives of ionic liquids that, playing the role of structure directing agents, were capable of designing the mesoporous structure of the resulting carbons is of particular interest. Meanwhile, deep eutectic solvents proved efficient in tailoring the structure comprised between large mesopores and small macropores, but the control over the smaller ones (e.g. small mesopores and micropores) is still a challenge as compared to ILs. Herein, we have used deep eutectic solvents composed of resorcinol, 4-hexylresorcinol and tetraethylammonium bromide for the synthesis of carbon monoliths with a tailor-made narrow microporosity. Behaving as molecular sieves, these carbons exhibited not only good capacities for CO2 adsorption (up to 3 mmol g−1) but also an outstanding – especially at low pressures – CO2–CH4 selectivity.

The treatment of bone lesions, including fractures, tumor resection and osteoporosis, is a common clinical practice where bone healing and repair are pursued. It is widely accepted that calcium phosphate-based materials improve integration of biomaterials with surrounding bone tissue and further serve as a template for proper function of bone-forming cells. Within this context, mineralization on preformed substrates appears as an interesting and successful alternative for mineral surface functionalization. However, mineralization of >true> 3D scaffolds -in which the magnitude of the third dimension is within the same scale as the other two- is by no means a trivial issue because of the difficulty to obtain a homogeneous mineral layer deposited on the entire internal surface of the scaffold. Herein, a >flow-through> electrodeposition process is applied for mineralization of 3D scaffolds composed of multiwall carbon nanotubes and chitosan. It is demonstrated that, irrespective of the experimental conditions used for electrodeposition (e.g., time, temperature and voltages), the continuous feed of salts provided by the use of a flow-through configuration is the main issue if one desires to coat the entire internal structure of 3D scaffolds with a homogeneous mineral layer. Finally, mineralized scaffolds not only showed a remarkable biocompatibility when tested with human osteoblast cells, but also enhanced osteoblast terminal differentiation (as early as 7 days in calcifying media). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Significant progress is described in the development of cellular solids, specifically functional and multifunctional foams, prepared by bioinspired approaches and consisting of green components. This article covers recent examples mainly developed at the Materials Science Institute of Madrid, ICMM-CSIC, on bionanocomposites and bioinspired materials conformed as foams. These novel hierarchical porous systems bring out a broad range of advanced applications from biomedical purposes to energy generation and storage. Recent progress in the development of advanced bionanocomposite and bioinspired foams with controlled porosity and low relative density is paving the way towards applications in a wide range of fields, from energy storage and insulating materials with reduced flammability for application in building and transport productivity sectors to novel scaffolds for tissue engineering and other biomedical purposes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The use of polyethylene oxide-polypropylene oxide-polyethylene oxide block-copolymers as a mediator in the laccase-induced graft polymerization of diacrylic derivate of polyethylene glycols resulted in the formation of PEG-g-F68 hydrogels. The proper oxygen content in the reaction medium to obtain reasonable polymerization conversions (i.e., on one hand, laccase needs oxygen as substrate whereas, on the other, oxygen is a strong inhibitor of radical polymerizations) was achieved by the use of an enzymatic scavenging system consisting of glucose oxidase and glucose. Eventually, laccase was immobilized within the resulting PEG-g-F68 hydrogel with full preservation of enzyme activity. Laccases have been used for bioremediation purposes because of their ability to degrade phenolic compounds. Thus, laccase-immobilized PEG-g-F68 hydrogels were submitted to the ISISA (ice segregation induced self-assembly) process for preparation of laccase-immobilized PEG-g-F68 cryogels which exhibited a macroporous structure where immobilized laccase preserved almost total activity (ca. 90%) for a period exceeding three months after preparation. Synergy between macroporous structure (deriving from the ISISA process), amphiphilic domains (deriving from graft copolymer) and activity of the immobilized enzyme provided outstanding adsorption capabilities to the cryogels (up to 235 mg g(-1))

Poly(vinyl alcohol) (PVA) scaffolds are prepared by a cryogenic process that consists of the unidirectional freezing of a PVA solution. The scaffolds exhibit a microchanneled structure, the morphology of which (in terms of pore diameter, surface area, and thickness of matter accumulated between adjacent microchannels) can be finely tailored by the averaged molecular weight of PVA, the PVA concentration in the solution, and the freezing rate of the PVA solution. The resulting PVA scaffolds are suitable substrates for drug-delivery purposes, the drug release being controlled (from tens of minutes up to several days) by the morphology of the microchanneled structure. In vitro experiments reveal the efficiency of PVA scaffolds for controlling the release of ciprofloxacin into a bacteria culture medium. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The method of a biocompatible bottom-up for the synthesis of hierarchical biohybrid materials, was described. The ice-segregation-induced self-assembly (ISISA) process for the preparation of hierarchical biohybrid materials. A polymer such as ply(vinyl alcohol) (PVA) and an enzyme such as pig liver esterase (PLE), was used for the investigation. The nature of a material with the hierarchically organized structure should be ceramic rather than polymeric. The hybrid nature of the hierarchical material comes from the PVA incorporation of an enzyme such PLE into a hierarchical hybrid material, with full preservation of the enzyme activity. The hybrid nature of the hierarchical material comes from the PVA incorporation and is crucial for the preservation of the enzyme structure and activity. The results show that this hierarchical biohybrid material will be a sophisticated structure with up to six levels of spatial organization, which is the ternary structure of the esterase.