Self-fluorescent antibiotic MoOx–hydroxyapatite: a nano-theranostic platform for bone infection therapies

Nowadays, the repair of large-size bone defects represents a huge medical challenge. A line of attack is the construction of advanced biomaterials having multifunctional properties. In this work, we show the creation of biocompatible MoOx-hydroxyapatite nanoparticles (nano-HA/MoOx) that simultaneously exhibit self-activated fluorescence and antibiotic skills. Along this text, we demonstrate that the insertion of molybdenum, an essential trace element, into the non-stoichiometric calcium deficient hydroxyapatite lattice generates intrinsic electronic point defects that exacerbate its epifluorescence blue emission and provokes new red emissions, preserving, always, its bioactivity. Furthermore, these point defects, acting as electron acceptors, stimulate the materials´ biological redox status and promote the death of pathogen microorganisms after their direct contact. A putative mechanism, by which bacteria lose electrons from their metabolic circuit that alter the function of their cytoplasmic membrane and potentially die, agrees with our results. Our findings highlight the importance of tuning the electronic communications between biomaterial interfaces and biological units, and support the use of self-fluorescent MoOx-hydroxyapatite nanoparticles as fundamental building blocks for new real-time imaging platforms against bone infection.Fil: Placente, Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; EspañaFil: Baldini, Monica Diana. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Laiuppa, Juan Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Electroquímica y Corrosión; ArgentinaFil: Santillán, Graciela Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Flexible ruthenium oxide-activated carbon cloth composites prepared by simple electrodeposition methods

This work focuses on the preparation of flexible ruthenium oxide containing activated carbon cloth by electrodeposition. Different electrodeposition methods have been used, including chronoamperometry, chronopotentiometry and cyclic voltammetry. The electrochemical properties of the obtained materials have been measured. The results show that the potentiostatic method allows preparing composites with higher specific capacitance than the pristine activated carbon cloth. The capacitance values measured by cyclic voltammetry at 10 mV s−1 and 1 V of potential window were up to 160 and 180 F g−1. This means an improvement of 82% and 100% with respect to the capacitance of the pristine activated carbon cloth. This excellent capacitance enhancement is attributed to the small particle size (4–5 nm) and the three-dimensional nanoporous network of the ruthenium oxide film which allows reaching very high degree of oxide utilization without blocking the pore structure of the activated carbon cloth. In addition, the electrodes maintain the mechanical properties of the carbon cloth and can be useful for flexible devices.Financial support by the Ministerio de Economía y Competitividad (MAT2010-15273) and Generalitat Valenciana and FEDER (PROMETEO/2009/047) projects are gratefully acknowledged. J.M.S. thanks Ministerio de Educación (SB2010-132)

Softwood Kraft Pulp-Derived Carbon-Supported PtNi Catalysts for the Electrooxidation of Ethanol

In this work, the biocarbons synthesized by fast pyrolysis at 350°C of raw (BK) and H3PO4 treated (TBK) fibrous fraction of non-bleached softwood kraft pulp has been proposed as novel supports for the deposition of PtNi nanocatalysts. The bimetallic nanoparticles were deposited by pulse microwave-assisted reduction using ethylene glycol both as solvent and reducing agent. The physicochemical properties of the resulting materials were evaluated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray microanalysis (EDX) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), whereas the electrochemical activity towards ethanol oxidation in acid medium was evaluated using cyclic voltammetry (CV) and chronoamperometry (CA). Nanosized PtNi particles with average diameters in the range of 2.9-4.1 nm and a nickel content of ca. 30 at. % were deposited over both softwood kraft pulp-derived carbon materials. The electrochemical measurements showed that the bimetallic nanoparticles deposited over the acid-treated biocarbon (PtNi/TBK) exhibit superior catalytic performance in terms of activity, onset potential, and poisoning tolerance. The mass activity of the PtNi nanocatalyst supported over TBK was about 1.3 and 6.3 times higher than that of the bimetallic nanoparticles deposited onto BK and Pt/C, respectively. The effect of the carbonaceous material on the electrocatalytic activity is discussed in detail.Fil: Nieva Lobos, María Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Moyano, Elizabeth Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Pt- and Ru-doped SnO2-Sb anodes with high stability in alkaline medium

Different Pt- and Ru-doped Ti/SnO2–Sb electrodes were synthesized by thermal decomposition. The effect of the gradual substitution of Sb by Ru in the nominal composition on the physicochemical and electrochemical properties were evaluated. The electrochemical stability of the electrodes was estimated from accelerated tests at 0.5 A cm–2 in 1 M NaOH. Both as-synthesized and deactivated electrodes were thoroughly characterized by scanning electron microscopy (SEM), energy-dispersive X-ray microanalysis (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction analysis (XRD). The incorporation of a small amount (about 3 at. %) of both Pt and Ru into the SnO2–Sb electrodes produced a 400-times increase in their service life in alkaline medium, with no remarkable change in the electrocatalysis of the oxygen evolution reaction (OER). It is concluded that the deactivation of the electrodes is promoted by alkaline dissolution of metal species and coating detachment at high potentials. The introduction of Pt has a coating compacting effect, and Ru(IV), at low amounts until 9.75 at. %, replaces the Sn(IV) cations in the rutile-like SnO2 structure to form a solid solution that strongly increases the stability of the electrodes. The observed Ru segregation and decreased stability for larger Ru contents (x > 9.75 at. %), together with the selective dissolution of Ru after deactivation, suggest that the formation of a homogeneous (RuδSn1−δ)O2 single-phase is crucial for the stabilization of these electrodes.The authors thank the MINECO, FEDER, and Generalitat Valenciana for the financial support (MAT2013-42007-P, PROMETEO2013/028 projects).Berenguer Betrián, R.; Sieben, JM.; Quijada Tomás, C.; Morallón, E. (2014). Pt- and Ru-doped SnO2-Sb anodes with high stability in alkaline medium. ACS Applied Materials and Interfaces. (6):22778-22789. https://doi.org/10.1021/am506958kS2277822789

Manganese (II,III) Oxide-Activated Carbon Black Supported PtRu Nanoparticles for Methanol Electrooxidation in Acid Medium

In this work, PtRu nanoparticles supported on hybrid manganese (II,III)-carbon composites were prepared by a microwave-assisted polyol process in ethylene glycol. The obtained PtRu/(100-x) C.xMn 3 O 4 catalysts were characterized by XRD diffraction, TEM, SEM-EDX analysis, ICP-AES and electrochemical techniques. Small and well-distributed nanoparticles of about 2.6 nm were obtained over the hybrid support. The as-prepared catalysts presented similar Pt : Ru atomic ratio (ca. 3.4 : 1), indicating that the composition of the bimetallic system is unaffected by the oxide content in the hybrid support. However, the noble metal loading increased with the increase in the oxide content due to the formation of more nucleation sites during microwave heating. The electrochemical experiments showed that the best performance and the lowest poisoning rate are obtained with PtRu/90C.10Mn 3 O 4 followed by PtRu/70C.30Mn 3 O 4 . The bimetallic catalyst supported over 90C.10Mn 3 O 4 exhibited a steady current density of 215 mA mg PtRu −1 at 0.5 V, which is 40 % higher than that of PtRu/C. This behavior is mainly associated with the ability of Mn 3 O 4 to provide a large extra amount of hydroxyl groups and promote the dehydrogenation of methanol.Fil: Comignani, Vanina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Sieben, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Brigante, Maximiliano Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Duarte, Marta María Elena. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentin

Asymmetric hybrid capacitors based on activated carbon and activated carbon fibre–PANI electrodes

Composites consisting of polyaniline (PANI) coatings inside the microporosity of an activated carbon fibre (ACF) were prepared by electrochemical and chemical methods. Electrochemical characterization of both composites points out that the electrodes with polyaniline show a higher capacitance than the pristine porous carbon electrode. These materials have been used to develop an asymmetric capacitor based on activated carbon (AC) as negative electrode and an ACF–PANI composite as positive electrode in H2SO4 solution as electrolyte. The presence of a thin layer of polyaniline inside the porosity of the activated carbon fibres avoids the oxidation of the carbon material and the oxygen evolution reaction is produced at more positive potentials. This capacitor was tested in a maximum cell voltage of 1.6 V and exhibited high energy densities, calculated for the unpackaged active materials, with values of 20 W h kg−1 and power densities of 2.1 kW kg−1 with excellent cycle lifetime (90% during the first 1000 cycles) and high coulombic efficiency.Financial support by the Ministerio de Ciencia e Innovación (MAT2010-15273 and CTQ2009-10813) and Generalitat Valenciana and FEDER (PROMETEO/2009/047 and ACOMP/2012/133) projects are gratefully acknowledged. J.M.S. thanks Ministerio de Educación (SB2010-132). D.S.T. thanks Ministerio de Ciencia e Innovación (BES-2010-035238)

Characterization of activated carbon fiber/polyaniline materials by position-resolved microbeam small-angle X-ray scattering

Activated carbon fiber (ACF)/polyaniline (PANI) materials have been prepared using two different methods, viz. chemical and electrochemical polymerization. Electrochemical characterization of both materials shows that the electrodes with polyaniline have a higher capacitance than does a pristine porous carbon electrode. To analyze the distribution of PANI within the ACF, characterization by position-resolved microbeam small-angle X-ray scattering (μSAXS) has been carried out. μSAXS results obtained with a single ACF indicate that, for the experimental conditions used, a PANI coating is formed inside the micropores and that it is higher in the external regions of the ACF than in the core. Additionally, it seems that the penetration of PANI inside the fibers occurs in a larger extent for the chemical polymerization or, in other words, for the electrochemically polymerized sample there is a slightly larger accumulation of PANI in the external regions of the ACF.Fil: Salinas-Torres, D.. Universida de Alicante; EspañaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Lozano-Castelló, D.. Universida de Alicante; EspañaFil: Morallón, E.. Universida de Alicante; EspañaFil: Burghammer, M.. EuropeanSynchrotronRadiationFacility; FranciaFil: Riekel, C.. EuropeanSynchrotronRadiationFacility; FranciaFil: Cazorla Amorós, Diego. Universida de Alicante; Españ

Controlled size formation of electrodeposited Pt-Ru nanostructured catalysts using chelating compounds

The electrodeposition of Pt and Ru on a oxidized graphite cloth from H 2PtCl6 and RuCl3 solution containing trisodium citrate (Cit), disodium tartrate (Tar) and disodium dihydrogen ethylenediaminetetraacetate (Na2H2EDTA) as complexants was investigated. SEM image of the electrode prepared without complexant showed a continuous compact and rough deposit that covers the entire graphite fibers surface displaying the structure of a coating film, whereas particles with uniform size and globular shape regularly distributed over the support were obtained when the complexants were added to the solution. Thus, EDX and XRD analysis revealed changes in Pt-Ru catalyst composition. It was concluded from electrocatalytic activity measurements that the electrodes prepared using chelating compounds exhibited better CO tolerance and performance for methanol oxidation than that without complexant. © 2011 Published by Elsevier B.V.Fil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentin

Carbon Nanotubes as Material Support for Pt-Based Catalysts and their Use in Direct Methanol Fuel Cells

In the last decade carbon nanotubes have turned out to be an important industrial material, being produced hundreds of tons each year. The unique structure of carbon nanotubes makes them an alternative material for catalyst support in fuel cells devices due to their unique one-dimensional nanostructure, high surface area, excellent electronic conductivity, and high chemical and mechanical stability. However, raw nanotubes do not have sufficient binding sites for anchoring metals nanoparticles, which frequently lead to poor dispersion and agglomeration of the nanoparticles. Hence, functionalization of carbon nanotubes is generally an essential issue to further applications. The presence of these surface functional groups modifies the chemical and physical properties of the carbon, improving wettability, adsorption, and cation exchange capacity. Furthermore, these groups act as nucleation centers or anchoring sites, limiting the particle growth and improving the dispersion of metallic crystallites and the stability of the supported catalysts. This chapter is devoted to review the available scientific literature, motivated by the enormous world-wide demand of increasing the production of energy from green renewable technologies. In the need of developing new, better-performing catalysts for direct methanol fuel cells applications, the present survey is focused on synthesis of catalytically active metal nanoparticles, such as Pt, and Pt-Me (Me: Ru, Sn, Mo, Os, etc.) decorating the external walls or the interior of the carbon nanotubes and carbon nanotubes/polymer composites.Fil: Sieben, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Duarte, Marta María Elena. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentin

Nanostructured Pt and Pt-Sn catalysts supported on oxidized carbon nanotubes for ethanol and ethylene glycol electro-oxidation

Pt and Pt-Sn catalysts supported on oxidized carbon nanotubes were prepared by multiple potentiostatic pulses and tested for ethanol and ethylene glycol electro-oxidation in sulfuric acid. The composed nanostructured materials were characterized via SEM, TEM, EDX and XRD analysis. Small metal nanoparticles (4-6 nm) forming 3-D nanostructured agglomerates (25-100 nm) distributed over the carbon substrate were formed. XRD results showed that the bimetallic electrocatalysts consisted of a Pt single-phase material, suggesting the formation of solid solutions over the entire composition range. The tin content in the alloys was between 10 and 40 at. %. Cyclic voltammetry and chronoamperometry measurements at room temperature showed that at potentials below 0.5 V, the bimetallic catalyst with 40 at. % Sn exhibited the highest activity for ethanol and ethylene glycol oxidation, whereas at potentials above 0.5 V, the alloy with 25 at. % Sn displayed better performance. This behavior can be explained by the synergistic effect between the facilitation of alcohol oxidation via oxygen-containing species adsorbed on Sn atoms, the alteration of the electronic structure of Pt atoms that weakens CO and intermediates adsorption, and the adequate Pt ensembles size. Besides, the increment of the lattice parameter and the presence of grain boundaries can enhance the adsorption of the alcohols and favor the splitting of the C-C bond. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Fil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Duarte, Marta María Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentin