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Scientific and technological production
Enzyme multilayer coatings inhibit Pseudomonas aeruginosa biofilm formation on urinary catheters
Ivanova, Kristina Dimitrova; Macedo Fernandes, Margarida Maria; Mendoza Gomez, Ernesto; Tzanov, Tzanko
Applied microbiology and biotechnology
Date of publication: 2015-01-15
Read the abstract View Share Reference managersBacteria use a signaling mechanism called quorum sensing (QS) to form complex communities of surface-attached cells known as biofilms. This protective mode of growth allows them to resist antibiotic treatment and originates the majority of hospital-acquired infections. Emerging alternatives to control biofilm-associated infections and multidrug resistance development interfere with bacterial QS pathways, exerting less selective pressure on bacterial population. In this study, biologically stable coatings comprising the QS disrupting enzyme acylase were built on silicone urinary catheters using a layer-by-layer technique. This was achieved by the alternate deposition of negatively charged enzyme and positively charged polyethylenimine. The acylase-coated catheters efficiently quenched the QS in the biosensor strain Chromobacterium violaceum CECT 5999, demonstrated by approximately 50 % inhibition of violacein production. These enzyme multilayer coatings significantly reduced the Pseudomonas aeruginosa ATCC 10145 biofilm formation under static and dynamic conditions in an in vitro catheterized bladder model. The quorum quenching enzyme coatings did not affect the viability of the human fibroblasts (BJ-5ta) over 7 days, corresponding to the extended useful life of urinary catheters. Such enzyme-based approach could be an alternative to the conventional antibiotic treatment for prevention of biofilm-associated urinary tract infections.
Self-assembly of collagen building blocks guided by electric fields
de la Rica, Roberto; Mendoza Gomez, Ernesto; Chow, Lesley W.; Cloyd, Kristy L.; Bertazzo, Sergio; Watkins, Hannah C.; Steele, Joseph A. M.; Stevens, Molly M.
Vol. 10, num. 19, p. 3876-3879
Date of publication: 2014-10-15
Read the abstract View Share Reference managersShow me the way: protein building blocks are programmed to assemble hierarchically and yield a defined fiber morphology of micrometric length and precise nanometric diameter. The key step of this method is to align the building blocks with an AC field prior to assembly. The resulting protein nanofibers are straightforwardly integrated with the circuitry for potential applications in bionanotechnology. (Figure Presented).
Enzyme multilayer coatings inhibit quorum sensing-regulated pseudomonas aeruginosa biofilm formation on silicone urinary catheters
Ivanova, Kristina Dimitrova; Macedo Fernandes, Margarida Maria; Mendoza Gomez, Ernesto; Tzanov, Tzanko
International Conference of Antimicrobial Research
Presentation's date: 2014-10-02
Presentation of work at congresses
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Decoration of carbon nanostructures with metal sulfides by sonolysis of single-molecule precursors
Estrada, Ana Cristina; Mendoza Gomez, Ernesto; Trindade, Tito
European journal of inorganic chemistry
Vol. 2014, num. 20, p. 3184-3190
Date of publication: 2014-07-01
Read the abstract View Share Reference managersCarbon nanostructures have emerged in recent decades as uniquely convenient materials for a number of technologies. Some of their envisaged applications require hybrid nanostructures that result from the coupling of semiconducting phases to the carbon materials. Here, we describe a new sonochemical method to decorate carbon-based materials (multiwalled carbon nanotubes, graphene oxide, and graphite flakes) with metal sulfide nanophases. In this research, we have used a Cd-II alkyldithiocarbamate complex as a single source to produce CdS nanophases that nucleate and grow over the carbon substrates. However, other metal sulfides can be produced by a similar methodology, which paves the way to a scalable method for the preparation of hybrid metal sulfide/carbon nanomaterials.
Building an antifouling zwitterionic coating on urinary catheters using an enzymatically triggered bottom-up approach
Diaz Blanco, Carlos; Ortner, Andreas; Dimitrov, Radostin; Navarro Santañes, Antonio; Mendoza Gomez, Ernesto; Tzanov, Tzanko
ACS applied materials and interfaces
Vol. 6, num. 14, p. 11385-11393
Date of publication: 2014-06-23
Read the abstract View Share Reference managersCatheter associated urinary tract infections are common during hospitalization due to the formation of bacterial biofilms on the indwelling device. In this study, we report an innovative biotechnology-based approach for the covalent functionalization of silicone catheters with antifouling zwitterionic moieties to prevent biofilm formation. Our approach combines the potential bioactivity of a natural phenolics layer biocatalytically conjugated to sulfobetaine-acrylic residues in an enzymatically initiated surface radical polymerization with laccase. To ensure sufficient coating stability in urine, the silicone catheter is plasma-activated. In contrast to industrial chemical methods, the methacrylate-containing zwitterionic monomers are polymerized at pH 5 and 50 °C using as an initiator the phenoxy radicals solely generated by laccase on the phenolics-coated catheter surface. The coated catheters are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) analysis, atomic force microscopy (AFM), and colorimetrically. Contact angle and protein adsorption measurements, coupled with in vitro tests with the Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus in static and dynamic conditions, mimicking the operational conditions to be faced by the catheters, demonstrate reduced biofilm formation by about 80% when compared to that of unmodified urinary catheters. The zwitterionic coating did not affect the viability of the human fibroblasts (BJ-5ta) over seven days, corresponding to the extended useful life of urinary catheters.
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; Gedanken, Aharon; 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.
Textiles are good substrates for growth of microorg anisms especially under moisture and temperature conditions found in hospitals. Microbia l 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 a nd the infection incidence. In this work, hybrid antimicrobial coatings were generated on cotton fab rics 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 pr ocessing time in order to improve the antibacterial properties of the fabric and ensure t heir biocompatibility. The highest antibacterial activity of the fabrics against two medically relev ant bacterial species was achieved in a 30 min sonochemical coating process using 2 mM ZnO NPs sus pension. When chitosan was simultaneously deposited with the same amount of Zn O, the obtained hybrid NPs coating displayed higher by 48 and 17 % antibacterial activ ity against Staphylococcus aureus and Escherichia coli , respectively. The presence of biopolymer also imp roved 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 fibrobl ast viability was observed for the hybrid ZnO/chitosan coating compared to the steady decreas e of cells viability over one week in contact with the fabrics coated with ZnO alone.
Gold nanoclusters for efficient removal of organic pollutants at room temperature
Santiago Redondo, Marta; Blázquez Gómez, 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.
Postprint (author’s final draft)
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
Vol. 5, num. 9, p. 775-781
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.
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
Vol. 43, num. 1, p. 1-7
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.
Producción y acondicionamiento de hidrógeno para pilas de combustible portátiles con microreactores y fotocatalizadores
Dominguez Escalante, Montserrat; Jimenez Divins, Nuria; Roig Costa, Maria; Casanovas Grau, Albert; Mendoza Gomez, Ernesto; Llorca Pique, Jordi
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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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.
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
Vol. 27, num. 1, p. 113-118
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
Vol. 99, num. 4, p. 1-3
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 gas
Prieto, Gonzalo; Concepcion, Patricia; Martinez, Agustin; Mendoza Gomez, Ernesto
Journal of catalysis
Vol. 280, num. 2, p. 274-288
Date of publication: 2011-06-13
Read the abstract View Share Reference managersA 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.
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
Vol. 421, num. 1-3, p. 129-133
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.
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.
Vol. 5, p. 19-22
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.
Obtenció i optimització de ceràmiques superconductores de YBCO per l’aplicació de limitació de corrent
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