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Scientific and technological production
Sonochemical coating of textiles with hybrid ZnO/chitosan antimicrobial nanoparticles
Petkova Petkova, Petya Stoyanova; Francesko, Antonio; Macedo Fernandes, Margarida Maria; Mendoza Gomez, Ernesto; Perelshtein, Ilana; Aharon, Gedanken; Tzanov, Tzanko
ACS applied materials and interfaces
Date of publication: 2014-01-09
Read the abstract View Share Reference managersTextiles are good substrates for growth of microorganisms especially under moisture and temperature conditions found in hospitals. Microbial shedding from the body occurs continuously at contact of the patient with textile materials used in medical practice, contributing to the occurrence of hospital acquired infections. Thus, the use of efficient antimicrobial textiles is necessary to prevent the transfer of pathogens and the infection incidence. In this work, hybrid antimicrobial coatings were generated on cotton fabrics by means of a one-step simultaneous sonochemical deposition of ZnO nanoparticles (NPs) and chitosan. The process was further optimized in terms of reagents concentration and processing time in order to improve the antibacterial properties of the fabric and ensure their biocompatibility. The highest antibacterial activity of the fabrics against two medically relevant bacterial species was achieved in a 30 min sonochemical coating process using 2 mM ZnO NPs suspension. When chitosan was simultaneously deposited with the same amount of ZnO, the obtained hybrid NPs coating displayed higher by 48 and 17 % antibacterial activity against Staphylococcus aureus and Escherichia coli, respectively. The presence of biopolymer also improved the durability of the antimicrobial effect of the coatings by 21 % for Staphylococcus aureus and 40 % for Escherichia coli, evaluated after applying multiple washing cycles at hospital laundering regimes. Finally, 87 % biocompatibility improvement supported by fibroblast viability was observed for the hybrid ZnO/chitosan coating compared to the steady decrease of cells viability over one week in contact with the fabrics coated with ZnO alone.
Exceptional oxidation activity with size-controlled supported gold clusters of low atomicity
Corma Canos, Avelino; Concepcion, Patricia; Boronat Zaragoza, Merce; Sabater, María José; Navas, Javier; José Yacamán, Miguel; Larios Rodriguez, Eduardo; Posadas, Alvaro; Lopez Quintela, Manuel Arturo; Buceta Fernández, David; Mendoza Gomez, Ernesto; Guilera, Gemma; Mayoral García, Álvaro
Date of publication: 2013-08-04
Read the abstract View Share Reference managersThe catalytic activity of gold depends on particle size, with the reactivity increasing as the particle diameter decreases. However, investigations into behaviour in the subnanometre regime (where gold exists as small clusters of a few atoms) began only recently with advances in synthesis and characterization techniques. Here we report an easy method to prepare isolated gold atoms supported on functionalized carbon nanotubes and their performance in the oxidation of thiophenol with O 2. We show that single gold atoms are not active, but they aggregate under reaction conditions into gold clusters of low atomicity that exhibit a catalytic activity comparable to that of sulfhydryl oxidase enzymes. When clusters grow into larger nanoparticles, catalyst activity drops to zero. Theoretical calculations show that gold clusters are able to activate thiophenol and O 2 simultaneously, and larger nanoparticles are passivated by strongly adsorbed thiolates. The combination of both reactants activation and facile product desorption makes gold clusters excellent catalysts. © 2013 Macmillan Publishers Limited. All rights reserved.
Gold nanoclusters for efficient removal of organic pollutants at room temperature
Santiago, Marta; Blázquez, Zaira; Galindo, Edurne; Alves, Leonor; Llorca Pique, Jordi; Mendoza Gomez, Ernesto
Submarine Air Monitoring and Air Purification
Presentation's date: 2013-10-15
Presentation of work at congresses
Read the abstract View Share Reference managersPreserving air quality of an enclosed space such as a submarine is a major challenge yet to be addressed. Currently, CO-H2 burners are employed to maintain a breathable air environment inside the submarine through catalytic conversion of contaminants being present in the air thereof into CO2 + H2O. These burners use a mixture of manganese and copper oxides referred to as hopcalite. Unfortunately, this catalyst presents a reasonable oxidation activity only above 150ºC as it suffers from strong inhibition by the presence of moisture. Furthermore, at such high operating temperatures, partial oxidation of hydrocarbons over the hopcalite may generate toxic by-products such as HF and HCl. Herein, we present a novel catalyst based on gold nanoclusters capable of eliminating massive amounts of organic pollutants at room temperature even in the presence of moisture.
Purificación del aire mediante conjuntos estables de átomos de oro
Improving immunosensor performance through oriented immobilization of antibodies on carbon nanotube composite surfaces
Puertas, Sara; de Gracia Villa, Maria; Mendoza Gomez, Ernesto; Jiménez Jorquera, Cecilia; de la Fuente, Jesús M.; Fernández-Sánchez, César; Grazú, Valeria
Biosensors and bioelectronics
Date of publication: 2013-05-05
Read the abstract View Share Reference managersWe report the straightforward oriented covalent attachment of antibodies (Abs) on the surface of carboxylated multiwalled carbon nanotube-polystyrene (MWCNT-PS) materials. The combination of this composite material, applied as a robust electrochemical transducer platform, and its covalent functionalization with Abs in a controlled way by means of a two-step process, could contribute to the development of highly sensitive immunosensor devices. Using the simple and versatile carbodiimide chemistry, Abs were attached to the carboxylic groups of the MWCNT-PS composite surfaces via their superficial amine groups. By taking into account the Ab isoelectric point and the net charge of the composite surface, we engineered an immobilization process to achieve the oriented binding of the Ab molecules by favoring an ionic pre-adsorption step before covalent binding occurred. Thus, the antigen binding capacity of the attached Abs was enhanced by up to 10 times with respect to the capacity estimated for a random spatial distribution of these molecules. The proposed strategy would also serve as a model for the efficient biofunctionalization of other carboxylated carbon-based polymer composite materials with potential applications in the biosensor field.
We report the straightforward oriented covalent attachment of antibodies (Abs) on the surface of carboxylated multiwalled carbon nanotube-polystyrene (MWCNT-PS) materials. The combination of this composite material, applied as a robust electrochemical transducer platform, and its covalent functionalization with Abs in a controlled way by means of a two-step process, could contribute to the development of highly sensitive immunosensor devices. Using the simple and versatile carbodiimide chemistry, Abs were attached to the carboxylic groups of the MWCNT-PS composite surfaces via their superficial amine groups. By taking into account the Ab isoelectric point and the net charge of the composite surface, we engineered an immobilization process to achieve the oriented binding of the Ab molecules by favoring an ionic pre-adsorption step before covalent binding occurred. Thus, the antigen binding capacity of the attached Abs was enhanced by up to 10 times with respect to the capacity estimated for a random spatial distribution of these molecules. The proposed strategy would also serve as a model for the efficient biofunctionalization of other carboxylated carbon-based polymer composite materials with potential applications in the biosensor field.
Nanotecnología para la calefacción de componentes de automóvil
Carod de Arriba, Xavier; Ferreté Aymerich, Eduard; Casanova Hormaechea, Ignasi; González Benítez, María Margarita; Mendoza Gomez, Ernesto
International Congress on Project Engineering
Presentation's date: 2012-07-11
Presentation of work at congresses
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Carbon nanotube composite peptide-based biosensors as putative diagnostic tools for rheumatoid arthritis
Villa Jiménez, María de Gracia; Jiménez Jorquera, Cecilia; Haro, I.; Gomara, M.J.; Sanmartí, R.; Fernández-Sánchez, César; Mendoza Gomez, Ernesto
Biosensors and bioelectronics
Date of publication: 2011-09-15
Read the abstract View Share Reference managersThis work reports on the fabrication and performance of a simple amperometric immunosensor device to be potentially used for the detection of serum anti-citrullinated peptide antibodies (ACPAs), which are specific for rheumatoid arthritis (RA) autoimmune disease. Sera of RA patients contain antibodies to different citrullinated peptides and proteins such as fibrin or filaggrin. Herein, a chimeric fibrin–filaggrin synthetic peptide (CFFCP1) was used as a recognition element anchored to the surface of a multiwalled carbon nanotube–polystyrene (MWCNT–PS) based electrochemical transducer. The transducer fabrication process is described in detail together with its successful electrochemical performance in terms of repeatability and reproducibility of the corresponding amperometric response. The resulting immunosensor approach was initially tested in sera of rabbits previously inoculated with the synthetic peptide and eventually applied to the detection of ACPAs in human sera. A comparative study was carried out using control serum from a blood donor, which demonstrated the selectivity of the immunosensor response and its sensitivity for the detection of anti-CFFCP1 antibodies present in RA patients.
Microelectromechanical resonators based on an all polymer/carbon nanotube composite structural material
Gutierrez, M.; Mendoza Gomez, Ernesto; Llobera, A.; Chu, V.; Conde, J.P.; Pais Antunes, Antonio
Applied physics letters
Date of publication: 2011-07-25
Read the abstract Access to the full text Share Reference managersCarboxylated multi-wall carbon-nanotubes (CNTs) monolayers are integrated on microfabricated all-polymer micro-electromechanical systems (pMEMS) resonator bridges on glass substrates. The structural layer of the MEMS bridges is a multilayer blended conductive polymer based on poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) to which functionalized CNT monolayers are electrostatically attached. The resonance frequency (fres) of electrostatically actuated pMEMS bridges was measured as a function of their length (32–67 lm) for different multilayer compositions. A significant increase in fres and quality factor (Q) with the addition of CNT monolayers to the PEDOT:PSS structural material is observed, demonstrating that CNT monolayers can be used to modulate pMEMS resonator properties.
New insights into the role of the electronic properties of oxide promoters in Rh-catalyzed selective synthesis of oxygenates from synthesis gasA series of 2.5% Rh/M@Al2O3 model catalysts were prepared by supporting Rh on high-area c-Al2O3, resulting in a surface covered by a monolayer (4.5–7 atoms/nm2) of MOx promoter oxides (M = Fe, V,Nb, Ta, Ti, Y, Pr, Nd,Sm). The catalysts were extensively characterized and evaluated for the conversion of synthesis gas to oxygenates at 553 K, 5.0 MPa, H2/CO = 1, and space velocity adjusted to attain CO conversion around 15%. The broad range of products formed depending on the specific promoter were, for the first time, quantitatively described using the selectivity parameter (Φ) defined here, which indicates, for a given reaction product, the contribution of carbon atoms derived from dissociative (Cdis) and nondissociative (Cins) activation of CO. Both the catalytic activity and, more interestingly, the selectivity pattern given by the Φ parameter were correlated with the electronic properties of the MOx promoters (i.e., electron-donating/electron-withdrawing capacity) for an extensive series of catalysts. Low-temperature and at-work CO-FTIR experiments suggested that the high activity and hydrocarbon selectivity displayed by catalysts promoted by more electron-withdrawing (acidic) oxide promoters (e.g., TaOx) were related to a higher proportion of bridged Rh2(CO)B adsorption sites and to a higher electron density (i.e., a higher electron back-donation ability) of the Rh0 surface sites, both factors promoting CO dissociation events. In contrast, linear CO adsorption on Rh0 sites displaying decreased electron backdonation in catalysts promoted by electron-donating (basic) oxides (e.g., PrOx, SmOx) was likely related to nondissociative CO activation and thus to the selective formation of oxygenates. TEM, XPS, and CO-FTIR results pointed to differences in morphology, rather than size or partial electronic charge, of the nanosized Rh0 crystallites as the likely cause for the different proportions of CO adsorption sites. The Rh0 NP morphology, both as-reduced and at-work, is a function of the electronic properties of the underlying promoter oxide.
PROCEDIMIENTO PARA LA OBTENCIÓN DE UN SUSTRATO CON NANOCLUSTERS DE Au FIJADOS EN SU SUPERFICIE, Y SUBSTRATO Y CATALIZADOR OBTENIDOS MEDIANTE DICHO PROCEDIMIENTOProcedimiento para la obtención de un sustrato con nanoclusters de Au fijados en su superficie, y substrato y catalizador obtenidos mediante dicho procedimiento.
Procedimiento para la obtención de un sustrato con nanoclusters 10 de Au (oro) fijados en su superficie, y substrato y catalizador obtenidos mediante dicho procedimiento. El procedimiento consiste en preparar una solución que contiene en forma dispersa nanoclusters de Au y, también en forma dispersa, un sustrato cuya superficie está funcionalizada con un polielectrolito que le confiere una carga eléctrica neta, y en someter dicha solución a una agitación intensa para provocar la fijación de nanoclusters de Au en la superficie del sustrato. Se obtiene como resultado un sustrato en cuya superficie se encuentran fijados nanoclusters de Au de forma dispersa sin presentar significativamente aglomerados. La invención también se refiere a un catalizador que comprende dicho sustrato con nanoclusters 20 de Au fijados en su superficie. Este catalizador es particularmente apto para su uso en reacciones de oxidación.
Resonant tunnelling and fast switching in amorphous-carbon quantum-well structures
Bhattacharyya, S.; Henley, S.J.; Mendoza Gomez, Ernesto; Gómez-Rojas, L.; Allam, J.; Silva, S.R.P.
Date of publication: 2006-01-01
Read the abstract View Share Reference managersThe need for fast electronic devices working under extreme conditions, particularly at high temperature and high voltage, led researchers to investigate the use of films based on diamond, graphitic carbon, amorphous carbon and other carbon nanostructures. In parallel, a different class of materials including disordered organic and inorganic materials has been studied, particularly for fast switching and large-area inexpensive electronics based on quantum transport9. However, fast-switching devices of amorphous semiconductors based on negative differential resistance or resonant tunnelling has not been achieved so far. Here, we show negative differential resistance peaks, quantized conductance and bias-induced switching with a high-frequency response from amorphous-carbon quantum-well structures. We also demonstrate sufficiently large values for the phase-coherence length and delocalized conduction in these band-modulated low-dimensional disordered carbon structures, which could lead to a new generation of unusual fast-switching devices.
Iron filled single-wall carbon nanotubes. A novel ferromagnetic medium
Borowiak-Palen, E.; Mendoza Gomez, Ernesto; Bachmatiuk, A.; Rummeli, M.H.; Gemming, T.; Nogues, T.; Kumryev, V.S.; Kalenczuk, R.J.; Pichler, T.; Silva, S.R.P.
Chemical physics letters
Date of publication: 2006-08-03
Read the abstract View Share Reference managersIn our study we use a highly efficient and simple methodology based on wet chemistry to fill single-wall carbon nanotubes (SWCNTs) with iron, and thus create quantum wires in a bulk. The research shown is unique in that it is the first experimental single-wall carbon nanotubes that have iron continuously within their core for extended length scale. The resulting Fe-filled SWCNTs show ferromagnetic behavior even at room temperature, despite the very small diameter. The intercalation of metals within single-wall carbon nanotube structures is a significant step towards the realization of the potential applications using these materials.
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