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Munoz-Bonilla A.,Autonomous University of Madrid | Fernandez-Garcia M.,CSIC - Institute of Polymer Science and Technology
European Polymer Journal | Year: 2015

Antimicrobial strategies combining polymer science and nanotechnology have attracted tremendous interest in the last decade because of their great potential in many applications. This feature article presents our vision for the continuous progress in this area. Then, its first part has been focused on the different methodologies used to obtain antimicrobial nanomaterials, such as self-assembly, nanoprecipitation, and electrospinning, among others. The surface nanostructuring of polymeric films and its effects on the antimicrobial behavior are briefly described in the second half. © 2015 Elsevier Ltd. All rights reserved.

Leon R.,University of Cambridge | Garcia A.G.,Autonomous University of Madrid | Garcia A.G.,Hospital Universitario Of La Princesa | Marco-Contelles J.,CSIC - Institute of Polymer Science and Technology
Medicinal Research Reviews | Year: 2013

With 27 million cases worldwide documented in 2006, Alzheimer's disease (AD) constitutes an overwhelming health, social, economic, and political problem to nations. Unless a new medicine capable to delay disease progression is found, the number of cases will reach 107 million in 2050. So far, the therapeutic paradigm one-compound-one-target has failed. This could be due to the multiple pathogenic mechanisms involved in AD including amyloid β (Aβ) aggregation to form plaques, τ hyperphosphorylation to disrupt microtubule to form neurofibrillary tangles, calcium imbalance, enhanced oxidative stress, impaired mitochondrial function, apoptotic neuronal death, and deterioration of synaptic transmission, particularly at cholinergic neurons. Approximately 100 compounds are presently been investigated directed to single targets, namely inhibitors of β and γ secretase, vaccines or antibodies that clear Aβ, metal chelators to inhibit Aβ aggregation, blockers of glycogen synthase kinase 3β, enhancers of mitochondrial function, antioxidants, modulators of calcium-permeable channels such as voltage-dependent calcium channels, N-methyl-D-aspartate receptors for glutamate, or enhancers of cholinergic neurotransmission such as inhibitors of acetylcholinesterase or butyrylcholinesterase. In view of this complex pathogenic mechanisms, and the successful treatment of chronic diseases such as HIV or cancer, with multiple drugs having complementary mechanisms of action, the concern is growing that AD could better be treated with a single compound targeting two or more of the pathogenic mechanisms leading to neuronal death. This review summarizes the current therapeutic strategies based on the paradigm one-compound-various targets to treat AD. A treatment that delays disease onset and/or progression by 5 years could halve the number of people requiring institutionalization and/or dying from AD. © 2011 Wiley Periodicals, Inc.

Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Diez-Vicente A.L.,Airbus
ACS Applied Materials and Interfaces | Year: 2014

Biodegradable nanocomposites were prepared by adding ZnO nanoparticles to bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) via solution casting technique. The morphology, thermal, mechanical, antibacterial, barrier, and migration properties of the nanocomposites were analyzed. The nanoparticles were uniformly dispersed within PHBV without the aid of coupling agents, and acted effectively as nucleating agents, raising the crystallization temperature and the level of crystallinity of the matrix while decreasing its crystallite size. A gradual rise in thermal stability was found with increasing ZnO loading, since the nanofillers hinder the diffusion of volatiles generated during the decomposition process. The nanocomposites displayed superior stiffness, strength, toughness, and glass transition temperature, whereas they displayed reduced water uptake and oxygen and water vapor permeability compared to the neat biopolymer, related to the strong matrix-nanofiller interfacial adhesion attained via hydrogen bonding interactions. At an optimal concentration of 4.0 wt % ZnO, the tensile strength and Young's and storage moduli showed a maximum that coincided with the highest crystallinity and the best barrier properties. PHBV/ZnO films showed antibacterial activity against human pathogen bacteria, and the effect on Escherichia coli was stronger than on Staphylococcus aureus. The overall migration levels of the nanocomposites in both nonpolar and polar simulants dropped upon increasing nanoparticle content, and were well below the limits required by the current normative for food packaging materials. These sustainable nanomaterials with antimicrobial function are very promising to be used as containers for beverage and food products as well as for disposable applications like cutlery or overwrap films. © 2014 American Chemical Society.

Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Diez-Vicente A.L.,Airbus
ACS Applied Materials and Interfaces | Year: 2014

Novel poly(ether ether ketone) (PEEK) based nanocomposites have been fabricated via melt-blending by addition of a carboxylated polymer derivative covalently grafted onto the surface of hydroxyl-terminated ZnO nanoparticles. Their morphology, thermal, mechanical, tribological, and antibacterial properties have been analyzed and compared with those of composites reinforced with pristine ZnO. The Fourier transform infrared (FT-IR) spectra corroborate the success of the grafting reaction, showing the appearance of signals related to ester linkages. Microscopic observations demonstrate that the polymer grafting improves the nanoparticle dispersion within the matrix. A progressive rise in thermal stability and flame retardant ability is found with increasing ZnO concentration, with an exceptional increment in the maximum degradation rate temperature of 70 C at 5.0 wt % loading. The crystallization and melting temperature of PEEK decrease upon incorporation of the grafted nanofillers, attributed to the restrictions on polymer chain mobility and crystal growth imposed by the strong ZnO-matrix interactions. Nanocomposites with polymer-grafted nanoparticles exhibit higher stiffness, strength, ductility, toughness and glass transition temperature whilst lower coefficient of friction and wear rate than the neat polymer and composites with bare ZnO. Further, they show superior antibacterial activity against both the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus bacteria. The antimicrobial effect increases upon raising nanoparticle content, and is stronger on E. coli. The approach used in this work is a simple, scalable, and efficient method to improve the performance of PEEK/ZnO nanocomposites for use in biomedical applications such as trauma, orthopedics, and spinal implants. © 2014 American Chemical Society.

Guarrotxena N.,CSIC - Institute of Polymer Science and Technology | Bazan G.C.,University of California at Santa Barbara
Advanced Materials | Year: 2014

Simultaneous detection of multiple proteins on a single spot can be efficiently achieved by using multiplexed surface-enhanced Raman spectroscopy (SERS)-encoded nanoparticle 'antitags' consisting of poly(ethylene glycol) (PEG)-protected silver dimers (and higher aggregates) and antibody-tagging entities. The effective SERS-based multivariate deconvolution approach guarantees an accurate and successful distinguishable identification of single and multiple proteins in complex samples. Their potential application in multiplexed SERS bioimaging technology can be easily envisaged. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Salavagione H.J.,CSIC - Institute of Polymer Science and Technology | Martinez G.,CSIC - Institute of Polymer Science and Technology
Macromolecules | Year: 2011

The preparation of nanocomposites of reduced graphene oxide (RGO) with poly(vinyl chloride) (PVC) is reported. Covalent modification of PVC with RGO and reduction/precipitation of graphite oxide and isocyanates-modified GO in the presence of PVC are studied. Among these methods it is proposed that only the former produces nanocomposites with enhanced final properties. The other method failed because it did not produce nanocomposites with different properties to the original polymer, probably due to the lack of effective interfacial interactions. The RGO-chemically modified PVC samples have different thermal and mechanical properties with respect to the parent polymer. A discussion on the dependence of the properties on the method of preparation is given. Furthermore, preliminary results based on the effect of the aspect ratio and surface chemistry of the filler are also given. © 2011 American Chemical Society.

Salavagione H.J.,CSIC - Institute of Polymer Science and Technology
Journal of Materials Chemistry A | Year: 2014

A decade after scientists from Manchester University isolated a single graphene sheet, the development of a method for mass-scale production of graphene of a similar quality to that obtained, and the implementation of a modular chemical route to incorporate graphene into multicomponent/ multifunctional materials are still fundamental challenges. The methods for graphene production and the synthetic procedures for its modification are limited to a handful of established methodologies, each with important limitations. In this manuscript a non-conventional electrochemical method for the preparation of high-quality graphene, and a recently reported general chemical approach for graphene functionalization through thiol-ene click reactions are highlighted. © the Partner Organisations 2014.

Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Naffakh M.,CSIC - Institute of Polymer Science and Technology | Marco C.,CSIC - Institute of Polymer Science and Technology | Ellis G.,CSIC - Institute of Polymer Science and Technology | Gomez-Fatou M.A.,CSIC - Institute of Polymer Science and Technology
Progress in Materials Science | Year: 2012

Polyetherketones, PEKs, are an important family of high-performance thermoplastic materials that display a unique combination of toughness, stiffness, thermooxidative stability, chemical and solvent resistance, flame retardancy, and retention of physical properties at high temperatures. A relevant step forward in the development of these materials has been the recent incorporation of nanofillers to extend their utility in advanced technological applications. This review provides an extensive overview of the research on PEK-based nanocomposites with a special emphasis on both carbon-based nanofillers, such as nanotubes or nanofibers, and inorganic nanoparticles. Nanocomposites can be fabricated by simple, low-cost conventional techniques such as extrusion and compression molding, generally combined with pre-processing stages involving mechanochemical treatments in organic solvents. Different strategies employed to efficiently incorporate carbon nanofillers into these matrices, including polymer functionalization, covalent grafting and nanofiller wrapping in compatibilizing systems are described. The analysis of the influence of the preparation and processing conditions as well as the nanofiller type, attributes and loading on the structure and properties of the resulting materials is also considered. Composites incorporating carbon nanofillers display remarkably improved thermal stability, electrical and thermal conductivity as well as mechanical property enhancements compared to the neat polymers. On the other hand, the incorporation of inorganic nanoparticles such as WS 2, SiO 2 or Al 2O 3 significantly enhances the tribological properties of the matrix, mainly the coefficient of friction and wear resistance. Finally, current and potential applications of these multifunctional nanocomposite materials in fields such as medicine, telecommunications, electronics, aerospace, automobile and chemical industries are described. © 2012 Elsevier Ltd. All rights reserved.

Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Gomez-Fatou M.A.,CSIC - Institute of Polymer Science and Technology | Ania F.,CSIC - Institute for the Structure of Matter | Flores A.,CSIC - Institute for the Structure of Matter
Progress in Materials Science | Year: 2015

This article reviews recent literature on polymer nanocomposites using advanced indentation techniques to evaluate the surface mechanical properties down to the nanoscale level. Special emphasis is placed on nanocomposites incorporating carbon-based (nanotubes, graphene, nanodiamond) or inorganic (nanoclays, spherical nanoparticles) nanofillers. The current literature on instrumented indentation provides apparently conflicting information on the synergistic effect of polymer nanocomposites on mechanical properties. An effort has been done to gather information from different sources to offer a clear picture of the state-of-the-art in the field. Nanoindentation is a most valuable tool for the evaluation of the modulus, hardness and creep enhancements upon incorporation of the filler. It is shown that thermoset, glassy and semicrystalline matrices can exhibit distinct reinforcing mechanisms. The improvement of mechanical properties is found to mainly depend on the nature of the filler and the dispersion and interaction with the matrix. Other factors such as shape, dimensions and degree of orientation of the nanofiller, as well as matrix morphology are discussed. A comparison between nanoindentation results and macroscopic properties is offered. Finally, indentation size effects are also critically examined. Challenges and future perspectives in the application of depth-sensing instrumentation to characterize mechanical properties of polymer nanocomposite materials are suggested. © 2014 Elsevier Ltd. All rights reserved.

Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Naffakh M.,CSIC - Institute of Polymer Science and Technology
Carbon | Year: 2012

An aminated poly(phenylene sulphide) derivative (PPS-NH 2) has been covalently anchored to the surface of epoxy and acid-functionalized single-walled carbon nanotubes (SWCNTs). The characterisation through Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis and Kaiser test corroborated the success of the grafting reactions, and allowed the identification and quantification of the covalent moieties. Scanning and transmission electron microscopy indicated an increase in the bundle diameter of the SWCNTs upon anchoring of the polymer chains. The results showed that the storage modulus, glass transition temperature and electrical conductivity of the polymer were exceptionally enhanced by the attachment to the SWCNTs. In contrast, the crystallization and melting temperature, degree of crystallinity and crystal size considerably decreased, as revealed by differential scanning calorimetry and X-ray diffraction experiments, due to the inactive nucleating role of these SWCNTs and the intense restrictions on chain mobility imposed by the SWCNT-polymer interactions. Acid-functionalized SWCNTs were more effective for reinforcing PPS-NH 2 than epoxy-functionalized SWCNTs, attributed to the formation of a larger number of covalent bonds, albeit led to a smaller increase in the electrical conductivity of the polymer. The results herein offer useful insights into the development of multifunctional CNT-reinforced thermoplastic composites for a wide variety of applications. © 2011 Elsevier Ltd. All rights reserved.

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