Actualment la recerca que desenvolupa el grup està orientada al voltant de tres eixos temàtics fonamentals: 1) Materials híbrids i conjugats formats per polímers conductors (PCs) amb aplicacions en Enginyeria de Teixits. Un dels nostres cavalls de batalla ha estat la utilització de materials híbrids orgànics PC/polímer aïllant i PC/proteïna, i de materials conjugats pèptid-PC com a matrius bioactives per la regeneració cel•lular. 2) Materials híbrids basats en polímers conductors amb aplicacions en Enginyeria de la Energia. Fonamentalment hem utilitzat PCs, sols o combinats, i materials híbrids PC/argiles per fabricar diferents dispositius capaços d’emmagatzemar energia elèctrica. 3) Mineralització de biomolècules i polímers conductors. Molt recentment hem iniciat una línia de recerca que té per objecte la síntesi de estructures minerals per biomineralitzar biomolècules, com el ADN, o per ser utilitzades com a nano- o micro-reactors per la síntesis de PCs.
This work presents the diagnosis procedure followed to determine the degree of damage of a 100-year-oldreinforced concrete building located in Barcelona city, the Sant-Manuel pavilion at Hôpital de la Santa Creui Sant-Pau. Some structural components of this building were affected by severe corrosion problems inthe reinforcing steel UPN profiles. In order to obtain a representative sample set, a preliminary inspectionof the macroscopic architectonic structure was applied at selected zones that exhibited the metallic back-bone. Gravimetric and electrochemical techniques have demonstrated that some UPN profiles presentedhigh corrosion rate. This was mainly due to the presence of water pipes installed beside the metallicstructure, which was a source of humidity, and also to the presence of calcium carbonate, calcium silicatehydrate, and calcium chloride substances inside the cement in direct contact with the metallic struc-tures, which were responsible for the steel depassivation. The work shows a practical example of howa suitable combination of chemical, physical and electrochemical techniques can be applied together tocharacterize a corrosion process, the obtained results validating and corroborating the prediction of thecorrosion rate in metallic structures.
Puiggali, A.; Micheletti, P.; Estrany, F.; del Valle, LJ.; Aleman, C. Advanced healthcare materials Vol. 6, num. 18, p. 1-11 DOI: 10.1002/adhm.201700453 Data de publicació: 2017-09-20 Article en revista
Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles are loaded with curcumin and piperine by in situ emulsion polymerization using dodecyl benzene sulfonic acid both as a stabilizer and a doping agent. The loaded drugs affect the morphology, size, and colloidal stability of the nanoparticles. Furthermore, kinetics studies of nonstimulated drug release have evidenced that polymer···drug interactions are stronger for curcumin than for piperine. This observation suggests that drug delivery systems based on combination of the former drug with PEDOT are much appropriated to show an externally tailored release profile. This is demonstrated by comparing the release profiles obtained in presence and absence of electrical stimulus. Results indicate that controlled and time-programmed release of curcumin is achieved in a physiological medium by applying a negative voltage of -1.25 V to loaded PEDOT nanoparticles.
En la última década, los polímeros conductores han despertado un gran interés tanto a nivel científico como tecnológico debido a las propiedades electroactivas que exhiben estos materiales. Por este motivo, en la presente Tesis Doctoral se han estudiado las aplicaciones de algunos de estos polímeros conductores, principalmente derivados del politiofeno, en el ámbito de la biomedicina y la biotecnología.Según los objetivos propuestos en esta Memoria, inicialmente se han realizado estudios relacionados con la preparación y caracterización de copolímeros de injerto empleando macromonómeros formados por oligotiofenos, a los que se les ha incorporado una cadena de polietilenglicol de peso molecular definido. Seguidamente se ha investigado su comportamiento mediante ensayos de citotoxicidad, adhesión celular y proliferación celular.A continuación, se ha realizado la síntesis y la caracterización de híbridos polímero conductor-péptido. Inicialmente, se ha optimizado el método de preparación de estos materiales empleando sistemas modelo, en los que el péptido ha sido re-emplazado por un amino ácido diseñado por similaridad química. Una vez evaluadas las diferentes estrategias sintéticas, se han obtenido híbridos formados por el mismo polímero y el péptido RG*D, donde RG*D es una secuencia análoga a la RGD (Arg-Gly-Asp) en la que el residuo central se ha sustituido por el amino ácido mencionado anteriormente. Para estos materiales se ha evaluado la biocompatibilidad y la bioactividad.La última parte de esta Tesis está orientada a la encapsulación de biomoléculas de pequeño tamaño en nanoestructuras poliméricas que pueden ser empleadas como sistemas transportadores y sistemas de liberación controlada cuando se incorporan al organismo. Los estudios se han iniciado encapsulando diferentes amino ácidos y se han acabado con péptidos hidrofóbicos lineales y cíclicos. En todos los casos la encapsulación se ha llevado a cabo mediante electrospraying o electrospinning.Los resultados obtenidos en esta Tesis se recogen en las siguientes publicaciones:- "Polythiophene-g-poly(ethylene glycol) Graft Copolymers from Electroactive Scaffolds".A.-D. Bendrea, G. Fabregat, J. Torras, S. Maione, L. Cianga, L. J. del Valle, I. Cianga & C. Alemán. J. Mater. Chem. B 2013, 1, 4135-4145.- "Effect of the Graft Ratio on the Properties of Polythiophene-g-poly(ethylene glycol)".S. Maione, G. Fabregat, L. J. del Valle, A.-D. Bendrea, L. Cianga, I. Cianga, F. Estrany & C. Alemán. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 239-252.- "Electro-Biocompatibility of Conjugates Designed by Chemical Similarity".S. Maione, G. Fabregat, L. J. del Valle, G. Ballano, C. Cativiela & C. Alemán. J. Pept. Sci. 2014, 20, 537-546.- "Electroactive Polymer-Peptide Conjugates for Adhesive Biointerfaces".S. Maione, A. M. Gil, G. Fabregat, L. J. del Valle, J. Triguero, A. Laurent, D. Jacquemin, F. Estrany, A. I. Jiménez, D. Zanuy, C. Cativiela & C. Alemán. Biomater. Sci. 2015, 3, 1395-1405.- Electrospray Loading and Release of Hydrophobic Gramicidin in Polyester Microparticles".S. Maione, L. J. del Valle, M. M. Pérez-Madrigal, C. Cativiela, J. Puiggalí & C. Alemán. RSC Adv. 2016, 6, 69634-69640.- "Biodegradable Nanofibrous Scaffolds as Smart Delivery Vehicles for Amino Acids".S. Maione, M. M. Pérez-Madrigal, L. J. Del Valle, A. Díaz, L. Franco, C. Cativiela, J. Puiggalí & C. Alemán. J. Appl. Polym. Sci. 2017, 134, 44883 (1-14).
Lipoxygenases (LOXs) are nonheme iron-containing enzymes catalyzing the dioxygenation of polyunsaturated fatty acids. LOX catalytic activity depends on the presence of iron in the active site and the iron removal is also able to affect the membrane binding properties of the enzyme. Leukotrienes biosynthesis is initiated by the action of 5-LOX at the level of nuclear membrane and the mechanism of enzyme-membrane interaction is thought to involve structural flexibility and conformational changes at the level of the protein tertiary structure. In this study, we have analyzed by molecular dynamics simulations the conformational changes induced by iron removal in 5-LOX. The data indicate that the degree of enzyme flexibility is related to the presence of iron into the active site that is able to stabilize the protein increasing its rigidity. These findings provide further evidence that the conformation and the functional activity of LOXs is tuned by the presence of iron at the active site, suggesting new approaches for the design of enzyme inhibitors.
Pérez-Madrigal, Maria M.; Torras, J.; Casanovas, J.; Häring, M.; Aleman, C.; Díaz-Díaz, D. Biomacromolecules Vol. 18, num. 9, p. 2967-2979 DOI: 10.1021/acs.biomac.7b00934 Data de publicació: 2017-08-11 Article en revista
This manuscript describes a new route to prepare rapidly Ca2+-free hydrogels from unmodified sodium alginate by simply mixing with small organic molecules such as poly(carboxylic acid) compounds as cross-linker agents instead of classical divalent metal salts such as CaCl2. Dimethyl sulfoxide (DMSO) was also found to induce the rapid gelation of aqueous alginate solutions. The gelation process takes place at room temperature, and depending on the composition, gels with good thermal (90-100 °C) and mechanical properties compared to classical metal-containing analogs are obtained. DMSO-based gels showed remarkable self-supporting and thixotropic properties, which can be tuned by the biopolymer concentration. Furthermore, oxalic acid-based gels show superior elasticity than HCl, CaCl2 and DMSO-based gels. The possibility to prepare monoliths, beads, and films of these gels provide them with significant versatility. In particular, films made of alginate and oxalic acid show good potential as synergistic anticancer drug delivery carrier. Computational studies using both quantum mechanical and classical force-field methodologies reveal that hydrogen bonding networks between water and DMSO molecules located close to the alginate chains are responsible for the stability of DMSO-based gels. In contrast, the cohesion of oxalic acid-based gels is a consequence of the coexistence of multiple ionic associations involving oxalate, alginate, and Na+ counterions, which stabilize the system and keep all the interacting species grouped.
Composites formed by poly(3,4-ethylenedioxythiophene) and alumina (PEDOT/Al2O3) have been prepared by in situ anodic polymerization. For this purpose, the stability of 1:1 and 4:1 monomer:alumina aqueous solutions has been examined as a function of the pH (2.3, 4.0, 7.0, 8.8, or 10.8). Results indicate that the monomer behaves as a dispersant that remains stable at the studied basic pHs despite they are close to the isoelectric point of alumina. Although the thermal stability of the composites is considerably affected by the pH of the reaction medium, its influence on the surface morphology is very small. Independently, of the synthetic conditions, the electrochemical properties were better for PEDOT/Al2O3 than for pure PEDOT, reflecting that alumina particles promote the charge mobility. The highest specific capacitance (SC; 141 F/g), which was 55% higher than that obtained for pure PEDOT, was achieved for the composite prepared at pH¿=¿8.8 using a 4:1 monomer:alumina ratio. These conditions favor the participation of OH– groups as secondary doping agents without degrading the polymer matrix and enhance the specific surface of the films, facilitating the ionic mobility. On the other hand, application of a multi-step polymerization strategy has shown that interfaces originated by consecutive steps enhance the SC.
AUMENTO DE LA ELECTROACTIVIDAD DE FILMS DE POLI(N-METILPIRROL) POR INCORPORACIÓN DE NANOPARTÍCULAS DE TRIÓXIDO DE MOLIBDENO
Francesc Estrany1,3, Margarita Sanchez-Jiménez1, y Carlos Alemán2,3
1 Departament d’Enginyeria Química, E. U. d’Enginyeria Tècnica Industrial de Barcelona, Universitat Politècnica de Catalunya (U.P.C.), Comte d’Urgell 187, 08036 Barcelona, Spain. Email: firstname.lastname@example.org.
2 Departament d’Enginyeria Química, E. T. S. d’Enginyers Industrials, U. P. C., Diagonal 647, 08028, Barcelona, Spain. Email: email@example.com.
3 Center for Research in Nano-Engineering, U. P. C., Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona E-08028, Spain. Email: firstname.lastname@example.org.
El poli-(N-metilpirrol) (PNMPy), tiene importantes aplicaciones como la detección selectiva de dopa-mina1, dispositivos electrocrómicos2, y en la fabricación de supercapacitores3.
En el presente trabajo, se han electrogenerado films compuestos de poli(N-metilpirrol) por incorpora-ción de partículas de MoO3, trabajando a potencial constante de 1,40 V durante 180s, a partir de una solución 10 mM de NMPy y 0,1 M de LiClO4, con 10% (sobre peso de monómero) de partículas del óxido en suspensión estable. Como disolvente se ha empleado una mezcla 75:25 acetonitrilo:agua para favorecer la suspensión y formación de films uniformes de PNMPy/MoO3. El resto de condicio-nes de trabajo aparecen en trabajos previos1,3. La respuesta eléctrica de los films se ha caracterizado por voltamperometría cíclica (solución 0,1 M de LiClO4 en acetonitrilo), y se ha realizado el análisis morfológico (SEM) y micro- y nanotopográfico (AFM) de su superficie (Fig. 1). El análisis elemental EDX de los films ha probado la presencia de partículas de MoO3 en los films de PNMPy.
Fig. 1. Imágenes 3D de AFM de (a) PNMPy y (b)
Nanocompuesto PNMPy/(10%) MoO3
Se ha constatado un aumento de la capacidad redox de almacenamiento de carga de los films de PNMPy, al formar el nanocompuesto por incorporación de las nanopartículas de MoO3. Este positivo efecto se ha relacionado con una mayor apertura de la superficie interfacial film-electrolito en el nanocompuesto, lo que está concordancia con los resultados del análisis nanotopográfico realizado.
Los autores agradecen al MINECO la financiación recibida del Proyecto: MAT2015-69367-R.
1. G. Fabregat, J. Casanovas, E. Redondo, E. Armelin y C. Alemán. Phys. Chem. Chem. Phys., 2014,16, 7850-7861.
2. S. Ahmad y S. Singh. Electrochem. Commun., 2008, 10, 895-898.
3. D. Aradilla, F. Estrany y Carlos Alemán. J. Phys. Chem. C, 2011, 115, 8430-8438
González, N.; Custal, M.A.; Rodríguez, D.; Riba, J.; Armelin, E. Materials research-Ibero-american journal of materials Vol. 20, num. 4, p. 1-10 DOI: 10.1590/1980-5373-MR-2017-0178 Data de publicació: 2017-07-01 Article en revista
The novelty of the present study relies on the straightforward sonication of ZnO and TiO2 and incorporation to a complex formulation of latex, with other several organic-inorganic additives that influences the cross-linking reactions. The new elastomer with particles carefully sonicated exhibit improved electrical and mechanical properties. Strong interaction among the nanoparticles and the polymer amorphous phase has been proved by means of FTIR, SEM and XRD analyses. The synergistic effect of hybrid fillers with nanometric dimensions can be used to design high-performance natural rubber nanocomposites with enhanced electrical resistance and good cross-linking degree.
We report the simple and fast fabrication of a bioactive integrated platform based on poly(3,4-ethylenedioxythiophene) and ¿-poly(glutamic acid)-cystamine hydrogel for the simultaneous delivery and electrochemical detection of dopamine. As shown in Figure 1, the different steps involved in the development of bioactive integrated platform consist of (i) anodic polymerization of 3,4-ethylenedioxythiophene on screen printed carbon electrodes, (ii) synthesis of biodegradable hydrogel in an aqueous environment on the surface of poly(3,4-ethylenedioxythiophene) film and gelatin which act as an anchor point, (iii) incorporation of dopamine into hydrogel by immersing method in acidic medium and finally (iv) release and electrochemical detection of dopamine in physiological buffer commonly used in biological research. The preliminary findings suggest that dopamine release rates from ¿-poly(glutamic acid)-cystamine hydrogels were dependent on the molecular weight of ¿-poly(glutamic acid), the cross-linking degree of the hydrogels, pH and ionic strength of the medium. On the other hand, the electrochemical assays indicate that we have successfully obtained high sensitive sensors (8·10-5 mA/µM dopamine) with a lower limit detection (0.45 µM).
Figure 1. Schematic representation of the different steps involved in the development of bioactive platform for the simultaneous drug delivery and electrochemical detection.
Fabregat, G.; Osorio, J.; Castedo, A.; Armelin, E.; Buendía, J.; Llorca, J.; Aleman, C. International Symposium Frontiers in Polymer Science Data de presentació: 2017-05-18 Presentació treball a congrés
We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1-2 minutes not only to conducting polymers (Figure 1) but also to electrochemically inert plastics, such as polyethylene, polypropylene, polyvinylpyrrolidone, poly(4-vinylphenol), polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert plastics are used, have been extensively investigated using X-ray photoelectron spectroscopy. Results clearly indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation promoting its detection. With this technology, which is based on the application of a very simple physical treatment rather than on the sophisticated chemical methods typically employed (e.g. functionalization, incorporation of catalytic nanoparticles and processing of the nanocomposites), we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.
Figure 1. SEM micrographs of (a) PEDOT and (b) PNCPy before (left) and after (right) plasma treatment using tcp= 2 min.
Figure 2. Control voltammogram of 10 ¿M DA in 0.1 M PBS at (a) polypropylene-, (b) polyvinylpyrrolidone-, (c) polycaprolactone- and (d) polystyrene-modified GCE.
Dielectric spectroscopy measures the dielectric properties of a medium as a function of frequency.
Beginning in the 1970s, research electrochemists and materials scientists began to discover the power of
Electrochemical Impedance Spectroscopy (EIS) as a tool for studying difficult and complicated systems.
Currently the EIS technique is much more accessible and widely used in research areas beyond the world
of electrochemistry. It requires an impedance analyser with frequency range from 106Hz to 10-2Hz
equipped with appropriate software. The development of modern technique of Broadband Dielectric
Spectroscopy (BDS), during the mid-nineties, with extremely wide frequency range (1012 Hz to 10-6 Hz)
allowed the study of molecular fluctuations and collective phenomena, charge and polarization effects in
amorphous, semi-crystalline, liquid crystalline polymers as well as in polymer composites.
In the present work, some examples of a variety of polymeric materials (Fig. 1), characterized with EIS at
Innovation in Materials and Molecular Engineering Group (IMEM’s Group), will be showed.
The characterization of electrical properties with impedance spectroscopy requires the interpretation of
the data with the help of suitable models, which are divided into two broad categories: equivalent circuit
models and process models. From Nyquist, Bode and permittivity plots (Figs. 2A-C) it is possible extract
quantitative parameters related to the polymer resistance, capacitance, conductivity, relative permittivity,
using the electrical equivalent circuit (EEC, Fig. 2D). Additionally, qualitative observations regarding
blistering formation under coating or permeability of organic coatings can be performed. Results can vary
depending on types of polymers, film thickness, number of polymer layers; and the nature and surface
treatment of the metal substrate used as working electrode.
The versatility of dielectric spectroscopy has made it to become a fundamental tool in multidisciplinary
design, characterization and application of advanced functional materials and systems applied in such
diverse fields as those ranging from nanotechnology to biology.
References: 1) Müller et. al, J. Phys. Chem. B, 118 (2014) 1102-1112.2) González et. al, Eur. Polym. J.,
75 (2015) 210–222. 3) Dalmoro et. al, Prog. .Org. Coat. 88 (2015) 181–190. 4) Pérez-Madrigal et al., ACS
Appl. Mater. Interfaces, 7 (2015) 1632-1643.
Poly(1,4-disubstituted 1,2,3-triazoles) made by copper-catalyzed azide-alkyne cycloaddition form strongly bonded interfaces with several metal substrates. In this work, a variety of alkyne and azide monomers were explored as precursors to anticorrosion coatings for a standard high-strength aluminum-copper alloy (tradename AA2024). Monomers of comparatively low functionality (diazide and trialkyne) were found to act as superior barriers for electrolyte transfer to the aluminum surface. These materials showed excellent resistance to corrosive pitting due to the combination of three complementary properties: good formation of highly crosslinked films, as observed by FTIR and DSC; good adhesion to the aluminum alloy substrate, as shown by pull-off testing; and excellent impermeability, demonstrated by electrochemical impedance spectroscopy (EIS).
The best result was obtained with 1A21B3 polymer (Fig. 1), which has an azide monomer with six methylene groups and one alkyne with triazine aromatic ring. This composition helped moderate the degree of crosslinking among polymer chains, offering a beneficial flexibility to the polymer film (Fig. 2A). Thus, the presence of bi-azide (A2) and tri-alkyne (B3) functionalities in poly(1,4-disubstituted 1,2,3-triazoles) coating has fulfilled the expected role by offering improved adhesion to the metal substrate and protective barrier properties at the film surface simultaneously (Figs. 2B-C).
Figure 1. Molecular formulas of azide (1A2) and alkyne (1B3) with schematic representation of hyperbranched poly(1,4-disubstituted 1,2,3-triazole).
Figure 2. A) Polytriazole 1A21B3 fabricated as flexible thin film, B) Pull-off adhesion values (*obtained from literature), and C) Corrosion potential evolution in NaCl 0.05M.
Reference: Armelin et. al ACS Applied Materials & Interfaces 2017, 9, 4231-4243.
The aim of this work is to show the experimental results corresponding to comparative corrosion studies carried out with five commercially pure different metals (iron, lead, zinc, aluminum, and copper) together with the alloy stainless steel 316. Field tests were performed in two different environments. The first, urban environment was represented by a zone corresponding to metropolitan area of Barcelona (Spain). The second environment, a marine environment, was selected on the coast line of the same metropolitan area. The time corresponding to field tests was a half year and the subsequent results were compared with laboratory accelerated tests from robotized equipment,
chosen to simulate urban and marine environments, by using aqueous sodium hydrogen sulphite and sodium chloride solutions, respectively.
Equivalent time between both field and accelerated tests has
been obtained. The results allow a good correlation between both types of exposures and make it possibleto study morphological and quantitative aspects of corrosion process, as well as the influence of different variables that influence the corrosion resistance of each metal and alloy. The main feature of this work is the collaboration between high school students and university faculty
, to illustrate, by active participation, the concept of “research work”, in the second year of high school, just before beginning their higher education studies.
Unusual gelation of acidic solutions was achieved using polycations bearing quaternary ammonium moieties. These ionene polymers are based on a disubstituted phenylene dibenzamide core, which allows the construction of different topomers (i.e. ortho-1, meta-2 and para-3). The topology of the polymers was found to play a key role on their aggregation behaviour both in pure water and in a variety of aqueous acidic solutions leading to the formation of stable acidic gels. Specifically, ortho-1 showed superior gelation ability than the analogues meta-2 and para-3 in numerous solutions of different pH and ionic strengths. Lower critical gelation concentrations, higher gel-to-sol transition temperatures and faster gelation were usually observed for ortho-1 regardless the solvent system. Detailed computational molecular dynamic simulations revealed a major role of the counterion (Cl-) and specific polymer¿polymer interactions. In particular, hydrogen bonds, N–H¿p interactions and intramolecular p–p stacking networks are distinctive in ortho-1. In addition, counterions located at internal hydration regions also affect to such polymer¿polymer interactions, acting as binders and, therefore, providing additional stability.
Mayans, E.; Casanovas Salas, Jordi; Gil, A.; Jimenez, A.; Cativiela, C.; Puiggali, J.; Aleman, C. Langmuir Vol. 33, p. 1-13 DOI: 10.1021/acs.langmuir.7b00622 Data de publicació: 2017-04-25 Article en revista
Microstructures from small phenylalanine-based peptides have attracted great attention lately because these compounds are considered to be a new class of tunable materials. In spite of the extensive studies on uncapped diphenylalanine and tetraphenylalanine peptides, studies on the self-assembly of uncapped triphenylananine (FFF) are very scarce and nonsystematic. In this work, we demonstrate that FFF assemblies can organize in a wide number of well-defined supramolecular structures, which include laminated helical-ribbons, leaflike dendrimers, doughnut-, needle-, and flower-shapes. These organizations are produced by the attractive or repulsive interactions between already formed assemblies and therefore can be controlled through the choice of solvents used as the incubation medium. Thus, the formation of the desired supramolecular structures is regulated through the protonation/deprotonation of the terminal groups, the polarity of the incubation medium, which affects both peptide···solvent interactions and the cavity solvation energy (i.e., solvent···solvent interactions), and the steric interactions between own assemblies that act as building blocks. Finally, the ß-sheet disposition in the latter structural motifs has been examined using both theoretical calculations and Fourier transform infrared spectroscopy. Results indicate that FFF molecules can adopt both parallel and antiparallel ß-sheets. However, the former one is the most energetically favored because of the formation of p–p stacking interactions between the aromatic rings of hydrogen-bonded strands.
The effect of counterions and multiple polymer chains on the properties and structure of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with ClO4- has been examined using density functional theory (DFT) calculations with periodic boundary conditions (PBCs). Calculations on a one-dimensional periodic model with four explicit polymer repeat units and two ClO4- molecules indicate that the latter are separated as much as possible, with the salt structure and band gap obtained from such ClO4- distribution being in excellent agreement with those determined experimentally. On the other hand, DFT calculations on periodic models that include two chains indicate that neighboring PEDOT chains are shifted along the molecular axis by a half of the repeat unit length, with dopant ions intercalated between the polymer molecules acting as cement. In order to support these structural features, classical molecular dynamics (MD) simulations have been performed on a multiphasic system consisting of 69 explicit PEDOT chains anchored onto a steel surface, explicit ClO4- anions embedded in the polymer matrix, and an acetonitrile phase layer onto the polymer matrix. Analyses of the radial distribution functions indicate that the all-anti conformation, the relative disposition of adjacent PEDOT chains and the distribution of ClO4- dopant ions are fully consistent with periodic DFT predictions. The agreement between two such different methodologies allows reinforcing the microscopic understanding of the PEDOT film structure.
Poly(N-methylpyrrole)/molybdenum trioxide composites have been prepared by in situ anodic polymerization using a 75:25 acetonitrile:water monomer solution, exfoliated molybdenum trioxide particles, and supporting electrolyte as reaction medium. The incorporation of molybdenum trioxide increases the ability of poly(N-methylpyrrole) to exchange charge reversibly (i.e., the electroactivity) by 47%. This has been attributed to the structural changes induced by the molybdenum trioxide, which transforms the uniform and compact surface morphology of poly(N-methylpyrrole) into a more open structure with distinctive topographic features at different levels. These trends facilitate the access and escape of dopant ions during oxidation and reduction processes, respectively, with respect to poly(N-methylpyrrole).
Mazzier, D.; Grassi, L.; Moretto, A.; Aleman, C.; Formaggio, F.; Toniolo, C.; Crisma, M. Journal of peptide science Vol. 23, num. 4, p. 346-362 DOI: 10.1002/psc.2957 Data de publicació: 2017-04-01 Article en revista
We performed the solution-phase synthesis of a set of model peptides, including homo-oligomers, based on the 2-aminoadamantane-2-carboxylic acid (Adm) residue, an extremely bulky, highly lipophilic, tricyclic, achiral, Ca-tetrasubstituted a-amino acid. In particular, for the difficult peptide coupling reaction between two Adm residues, we took advantage of the Meldal's a-azidoacyl chloride approach. Most of the synthesized Adm peptides were characterized by single-crystal X-ray diffraction analyses. The results indicate a significant propensity for the Adm residue to adopt ¿-turn and ¿-turn-like conformations. Interestingly, we found that a -CO-(Adm)2-NH- sequence is folded in the crystal state into a regular, incipient ¿-helix, at variance with the behavior of all of the homo-dipeptides from Ca-tetrasubstituted a-amino acids already investigated, which tend to adopt either the ß-turn or the fully extended conformation. Our density functional theory conformational energy calculations on the terminally blocked homo-peptides (n = 2–8) fully confirmed the crystal-state data, strongly supporting the view that this rigid Ca-tetrasubstituted a-amino acid residue is largely the most effective building block for ¿-helix induction, although to a limited length (anti-cooperative effect).
Fabregat, G.; Osorio-Madrigal, J.; Castedo, A.; Armelin, E.; Buendía-Morales, J.J.; Llorca, J.; Aleman, C. Applied surface science Vol. 399, p. 638-647 DOI: 10.1016/j.apsusc.2016.12.137 Data de publicació: 2017-03-31 Article en revista
We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1–2 min not only to conducting polymers but also to electrochemically inert polymers, such as polyethylene, polypropylene, polyvinylpyrrolidone, polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert polymers are used, have been investigated using X-ray photoelectron spectroscopy. Results indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation. With this technology, which is based on the application of a very simple physical functionalization, we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.
Rivas, M.; Franco, M.; del Valle, LJ.; Turon, P.; Aleman, C.; Puiggali, J. International Conference on Multifunctional, Hybrid and Nanomaterials p. P3-170 Data de presentació: 2017-03-06 Presentació treball a congrés
The influence of the preparation method in the properties of poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes used to manufacture organic energy storage devices, as for example supercapacitors, have been examined by considering a reduction of both monomer and supporting electrolyte concentrations during the anodic polymerization reaction. Thus, the excellent electrochemical properties of PEDOT films prepared using quiescent solutions have been preserved by applying controlled agitation to the polymerization process, even though the concentration of monomer and supporting electrolyte were reduced 5 and 2 times, respectively. For example, the charge stored for reversible exchange in a redox process, the electrochemical stability and the current productivity of films achieved using quiescent solutions have been preserved using a dynamic reaction medium in which the concentrations of monomer and supporting electrolyte are several times lower. The excellent properties of PEDOT electrodes prepared using optimized dynamic conditions have also been proved by constructing a symmetric supercapacitor. This energy storage device, which has been used as power source for a LED bulb, is rechargeable and exhibits higher charge-discharge capacities than supercapacitors prepared with electrodes derived from quiescent solutions. In addition of bring an efficacious procedure for preparing cost-effective PEDOT films with excellent properties, the proposed dynamic conditions reduce the environmental hazards of depleted reaction media.
Pérez-Madrigal, Maria M.; Edo, M.; Diaz, A.; Puiggali, J.; Aleman, C. Journal of Physical Chemistry C Vol. 121, num. 6, p. 3182-3193 DOI: 10.1021/acs.jpcc.6b10693 Data de publicació: 2017-02-16 Article en revista
Biosynthetic poly-¿-glutamic acid (¿-PGA) has been used to produce hydrogels using cystamine as cross-linker and 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide (EDC methiodide) as condensing agent. Eight different hydrogels with different properties were formulated by varying both the molecular weight of ¿-PGA and the ¿-PGA/EDC/cystamine ratio and subsequently characterized. The most appropriate ¿-PGA hydrogel was selected to perform as solid electrolytic medium in organic electrochemical supercapacitors (OESCs) using poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes based on their mechanical behavior (consistency and robustness to hold the PEDOT electrodes), morphology, and influence on the electrochemical response of the organic electrode (i.e., specific capacitance and both maximum energy and power density values). Hence, PEDOT/¿-PGA energy storage devices fabricated using the most adequate hydrogel formulation displayed a supercapacitor response of 168 F/g and a capacitance retention of 81%. Moreover, after evaluating the maximum energy and power densities (Ragone plot), cyclability, long-term stability, leakage current, and self-discharging response of PEDOT/¿-PGA OESC devices, results allow us to highlight the merits and great potential of ¿-PGA hydrogels as sustainable ion-conductive electrolytes for environmentally friendly energy storage technologies.
The conformational preferences of the Arg-GlE-Asp sequence, where GlE is an engineered amino acid bearing a 3,4-ethylenedioxythiophene (EDOT) ring as side group, have been determined combining density functional theory calculations with a well-established conformational search strategy. Although the Arg-GlE-Asp sequence was designed to prepare a conducting polymer–peptide conjugate with excellent electrochemical and bioadhesive properties, the behavior of such hybrid material as adhesive biointerface is improvable. Results obtained in this work prove that the bioactive characteristics of the parent Arg-Gly-Asp sequence become unstable in Arg-GlE-Asp because of both the steric hindrance caused by the EDOT side group and the repulsive interactions between the oxygen atoms belonging to the backbone amide groups and the EDOT side group. Detailed analyses of the conformational preferences identified in this work have been used to re-engineer the Arg-GlE-Asp sequence for the future development of a new electroactive conjugate with improved bioadhesive properties. The preparation of this new conjugate is in progress.
Armelin, E.; Whelan, R.; Martinez, Y.; Aleman, C.; Finn, M.; Díaz-Díaz, D. ACS applied materials and interfaces Vol. 9, num. 4, p. 4231-4243 DOI: 10.1021/acsami.6b14174 Data de publicació: 2017-02-01 Article en revista
Organic polymers are widely used as coatings and adhesives to metal surfaces, but aluminum is among the most difficult substrates because of rapid oxidative passivation of its surface. Poly(1,4-disubstituted 1,2,3-triazoles) made by copper-catalyzed azide–alkyne cycloaddition form strongly bonded interfaces with several metal substrates. In this work, a variety of alkyne and azide monomers were explored as precursors to anticorrosion coatings for a standard high-strength aluminum–copper alloy. Monomers of comparatively low valency (diazide and trialkyne) were found to act as superior barriers for electrolyte transfer to the aluminum surface. These materials showed excellent resistance to corrosive pitting due to the combination of three complementary properties: good formation of highly cross-linked films, as observed by Fourier transform infrared spectroscopy and differential scanning calorimetry; good adhesion to the aluminum alloy substrate, as shown by pull-off testing; and excellent impermeability, as demonstrated by electrochemical impedance spectroscopy.
Peptides homing tumor vasculature are considered promising molecular imaging agents for cancer detection at an early stage. In addition to their high binding affinity, improved tissue penetrating ability, and low immunogenicity, they can deliver targeted anticancer drugs, thus expanding therapeutic treatments. Among those, CREKA, a linear peptide that specifically binds to clotted-plasma proteins in tumor vessels, has been recently employed to design bioactive systems able to target different cancer types. Within this context, this paper explores the biorecognition event between CR(NMe)EKA, an engineered CREKA-analog bearing a noncoded amino acid (N-methyl-Glu) that is responsible for its enhanced activity, and clotted-plasma proteins (fibrin and fibrinogen) by nanomechanical detection. Specifically, the tumor-homing peptide was covalently attached via epoxysilane chemistry onto silicon microcantilever chips that acted as sensors during dynamic mode experiments. Before that, each step of the functionalization process was followed by contact angle measurements, interferometry, X-ray photoelectron spectroscopy, and atomic force microscopy, thus revealing the applied protocol as a suitable strategy. The fibrin(ogen)-binding induced by CR(NMe)EKA was detected by the resonance frequency shift of the cantilevers, and a detection limit of 100¿ng/mL was achieved for both proteins. Even though further development is required, this work reflects the promising application of emerging technologies capable of assisting in the comprehension of biological interactions and their implications in the biotechnological field.
Maione, S.; Pérez-Madrigal, M.M.; del Valle, LJ.; Diaz, A.; Catiavela, C.; Franco, M.; Puiggali, J.; Aleman, C. Journal of applied polymer science Vol. 134, num. 22 DOI: 10.1002/app.44883 Data de publicació: 2017 Article en revista
The encapsulation of amino acids (AAs) and their correct preservation before they are ingested are challenging tasks. Nonpolar (l-alanine and l-phenylalanine), polar (l-cysteine hydrochloride and l-asparagine), and charged (l-lysine hydrochloride and l-aspartic acid) AAs were loaded into biodegradable and nontoxic poly(tetramethylene succinate) (PE44) nanofibers (NFs) with electrospinning. The loading of AAs considerably affected the morphology, topography, thermal properties, and wettability of the PE44 NFs. Furthermore, although the AAs crystallized in a phase separated from the polymeric matrix, the distribution of such crystals changed into PE44 NFs and depended on their chemical nature. Release assays in enzyme-free solutions provided evidence that very significant amounts of AAs were retained in the NFs after 7 days, whereas assays in the lipase-containing solution (because lipase performs essential roles in the digestion) showed almost complete release after a few hours. Lipase preferentially attacked the PE44 regions responsible for the retention of AAs in the biphasic system and favored the almost immediate release of the biomolecules. The results displayed in this study, combined with the biocompatibility, biodegradability, and potential use of the PE44 NFs as edible nonnutritional elements, suggest that the loaded PE44–AA NFs could be used to supply essential and conditional AAs.
We report the noticeable control exerted by the surface in the self-assembly of a highly hydrophobic triphenylalanine peptide with fluorenyl functionalities blocking the two ends. The remarkable differences observed among the polymorphic hierarchical assemblies obtained onto silanized glass, scratched glass, stainless steel, exfoliated mica, silicon wafer, carbon, polytetrafluoroethylene, plasma-functionalized, polystyrene and nitrocellulose substrates are consequence of the balance between peptide···peptide and peptide···surface interactions. This balance is greatly influenced by the surface characteristics, as defined by the wettability (hydrophobicity or hydrophilicity) and roughness (degree of flatness and regularity). Furthermore, very stable dendritic structures, in which primary frameworks nucleated from the center grow according to a 4-fold pseudo-symmetry branching, have been obtained onto hydrophilic treated polystyrene.
Natural rubber (NR) is mostly used in the form of solid vulcanized rubber, which is employed in the production of thin-walled products such as surgical gloves, balloons, tires, and other applications1. In addition to the vulcanization additives and accelerators of the vulcanization process, many other compounding ingredients are present in the commercial product, including fillers, pigments, plasticizers, reinforcing resins, and others2. In this investigation we evaluated the influence of the reduction of particle size, such as zinc oxide and titanium oxide, in the dielectric properties of vulcanized rubber films. Fig. 1a plots the leakage current versus voltage until breakdown conditions. The addition of nano-sized filler in the latex formulation decreased the leakage current and increased the breakdown voltage values when the solid particles were sonicated for 10 min. Therefore, the addition of nano-filler particles favours the reduction of defects inside the composite material and also improves the local electric field dissipation.
Green nanocomposites for electrical insulating applications can be manufactured by combining a natural polymer, such as the natural rubber (NR), with ferroelectric ceramics, like barium titanate (BaTiO3). This filler has been intensively investigated due to its high dielectric constant1. However, BaTiO3 has a poor compatibility with polymer matrices, and also its high surface energy promotes nanoparticles agglomeration. Therefore, in order to improve their dispersion into polymer matrices there are several surface modification methods, like: hydroxylation, amination, sulphonation, and grafting polymers2. The aim of the present work is to improve the compatibility of NR polymer matrix with BaTiO3 nanoparticles. For this purpose, the BaTiO3 particles were chemically modified with H2O2 to obtain OH groups on their surface (Fig. 1a). The hydroxylation process was carried out by the reaction of 10 g of BaTiO3 nanoparticles and 80 ml of H2O2 aqueous solution (30 wt%) and refluxed at 105 ºC for 24 h3. Figure 1b shows the plot of the leakage current versus voltage until breakdown. It can be observed that the addition of BaTiO3 nanofillers 0.25wt %; 0.5 wt %, 1 wt %, 5 wt % and 10wt %.) in the latex formulation increases the breakdown voltage. Therefore, the dielectric strength of the material has been improved. Chemical impedance analysis results also indicated that the composite film is highly insulating due to the better compatibility of the NR with the ceramic particles, thus decreasing the ionic conductivity inside the polymer matrix (Fig. 1c).
Puiggali, A.; Pérez-Madrigal, M.M.; del Valle, LJ.; Armelin, E.; Casas, M.; Michaux, C.; Perpete, E.; Estrany, F.; Aleman, C. Nanoscale Vol. 8, num. 38, p. 16922-16935 DOI: 10.1039/c6nr04948f Data de publicació: 2016-10-14 Article en revista
Bioinspired free-standing nanomembranes (FSNMs) for selective ion transport have been tailored by immobilizing the Omp2a ß-barrel membrane protein inside nanoperforations created in flexible poly(lactic acid) (PLA) nanomembranes. Perforated PLA FSNMs have been prepared by spin-coating a 99 : 1 PLA : poly(vinyl alcohol) mixture, and through a phase segregation process nanofeatures with dimensions similar to the entire nanomembrane thickness (~110 nm) were induced. These nanofeatures have subsequently been transformed into nanoperforations (diameter: ~51 nm) by selective solvent etching. The protein confined inside the nanopores of PLA FSNMs preserves the ß-barrel structure and organizes in ovoid aggregates. The transport properties of Na+, K+, and Ca2+ across non-perforated PLA, nanoperforated PLA, and Omp2a-filled nanoperforated PLA have been monitored by measuring the nanomembrane resistance with electrochemical impedance spectroscopy (EIS). The incorporation of nanoperforations enhances the transport of ions across PLA nanomembranes, whereas the functionality of immobilized Omp2a is essential to exhibit effects similar to those observed in biological nanomembranes. Indeed, Omp2a-filled nanoperforated PLA nanomembranes exhibit stronger affinity towards Na+ and Ca2+ ions than towards K+. In summary, this work provides a novel bioinspired strategy to develop mechanically stable and flexible FSNMs with channels for ion transport, which are precisely located inside artificial nanoperforations, thus holding great potential for applications in biofiltration and biosensing
In recent years, ceramic nanofillers such as BaTiO3 incorporated in polymer matrix have been prepared as engineering materials with high dielectric properties1. However, agglomeration of ceramic dopants enhances electron conduction and therefore a high dielectric loss due to increased porosity2. However, surface hydroxylation treatment of the ceramic particles with H2O2 (figure 1a) is an effective method to improve nanoparticles dispersion into the polymer matrix3. The main goal of this work is to improve the electrical properties of natural rubber (NR). BaTiO3 nanoparticles functionalized with H2O2 were added to natural rubber formulation at different ratios: 0.25 wt %; 0.5 wt %, 1 wt % , 5wt % and 10 wt %. The results attained in DC dielectric tests, for positive and negative polarity (figure 1b), show that an increasing content of perovskite in NR reduces the leakage current of the composite material incorporating BaTiO3 surface-functionalized nanocomposite samples, compared to NR (polymer without nanoparticles, used as reference sample). This could be attributed to the trap effect induced by the modified BaTiO3-OH nanofillers. Figure 1b also shows the perforation produced by the dielectric breakdown in DC, which corroborates that if a good dispersion of the ceramic filler is achieved, an improvement of the electric field distribution within the polymeric matrix is obtained. As a consequence, dielectric properties and breakdown strength are enhanced as well.
Figure 1. a) Surface functionalization of BaTiO3 nanoparticles and nanocomposite with NR. b) Positive and negative DC polarity dielectric tests of the reference NR samples and NR modified composites with different concentrations of barium titanate.
1. N. Gonzalez, M. Custal, S. Lalaouna, J.R. Riba, E. Armelin,Eur. Polym. J., 75, 210–222, 2015.
2. N. Sharma, A. Gaur, U. Kr Gaur. J. Ceram. Int., Part B, 2014, 40, 16441-16448.
3. C. Sameera Devi, G. Kumar, G. Prasad. Spectrochim. Acta Mol. Biomol. Spectrosc. 2015,136,366-372.
The properties as biointerfaces of electroactive conducting polymer–peptide biocomposites formed by poly(3,4-ethylenedioxythiophene) (PEDOT) and CREKA or CR(NMe)EKA peptide sequences (where Glu has been replaced by N-methyl-Glu in the latter) have been compared. CREKA is a linear pentapeptide that recognizes clotted plasma proteins and selectively homes to tumors, while CR(NMe)EKA is an engineer to improve such properties by altering peptide–fibrin interactions. Differences between PEDOT-CREKA and PEDOT-CR(NMe)EKA reflect dissemblance in the organization of the peptides into the polymeric matrix. Both peptides affect fibrinogen thrombin-catalyzed polymerization causing the immediate formation of fibrin, whereas in the absence of thrombin this phenomenon is only observed for CR(NMe)EKA. Consistently, the fibrin-adsorption capacity is higher for PEDOT-CR(NMe)EKA than for PEDOT-CREKA, even though in both cases adsorbed fibrin exhibits round-like morphologies rather than the characteristic fibrous structure. PEDOT-peptide films coated with fibrin are selective in terms of cell adhesion, promoting the attachment of metastatic cells with respect to normal cells.
Thermodynamics and the solvent role in the acceleration of the Diels–Alder reaction between cyclopentadiene (CPD) and methyl vinyl ketone (MVK) have been revisited. In this work we use an ab initio hybrid QM/MM-MD scheme combined with multiple steered molecular dynamics to extract the free energy pofile in water and methanol using the bidirectional Minh–Adib estimator. We obtain 18.7 kcal mol–1 and 20.8 kcal mol–1 free energy barrier for the reaction in water and methanol, respectively. This methodology reproduces experimental values with an absolute error of about 0.8 kcal mol–1. The experimental difference between the activation free-energy barriers of water and methanol is also reproduced with an absolute error of about 0.1 kcal mol–1. We explore the charge transfer evolution along reaction coordinates to characterize the electronic behavior for this reaction. It is shown that the solvent molecules around the reaction system produce a global polarization along the reaction coordinate which is consistent with the solvent polarity. The results highlight the role of hydrogen bonding formed in the transition state to stabilize the system charge reorganization in the reaction process.
The properties as biointerfaces of electroactive conducting polymer-peptide biocomposites formed by poly(3,4-ethylenedioxythiophene) (PEDOT) and CREKA or CR(NMe)EKA peptide sequences (where Glu has been replaced by N-methyl-Glu in the latter) have been compared. CREKA is a linear pentapeptide that recognizes clotted plasma proteins and selectively homes to tumors, while CR(NMe)EKA is an engineer to improve such properties by altering peptide-fibrin interactions. Differences between PEDOT-CREKA and PEDOT-CR(NMe)EKA reflect dissemblance in the organization of the peptides into the polymeric matrix. Both peptides affect fibrinogen thrombin-catalyzed polymerization causing the immediate formation of fibrin, whereas in the absence of thrombin this phenomenon is only observed for CR(NMe)EKA. Consistently, the fibrin-adsorption capacity is higher for PEDOT-CR(NMe)EKA than for PEDOT-CREKA, even though in both cases adsorbed fibrin exhibits round-like morphologies rather than the characteristic fibrous structure. PEDOT-peptide films coated with fibrin are selective in terms of cell adhesion, promoting the attachment of metastatic cells with respect to normal cells.
Pérez-Madrigal, Maria M.; Ochoa, D. A.; Garcia, J. E.; Armelin, E.; Aleman, C. Journal of polymer science. Part B, polymer physics Vol. 54, num. 18, p. 1896-1905 DOI: 10.1002/polb.24095 Data de publicació: 2016-09-15 Article en revista
Dielectric elastomer actuators (DEAs) transform electrical energy into mechanical work. However, despite displaying exceptional features, the low permittivity of elastomers restricts their application. Hence, to overcome this limitation, DEAs are fabricated by dispersing poly(3-methylthiophene acetate) (P3TMA), a polarizable conducting polymer, into poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), a thermoplastic elastomer with excellent mechanical properties. Although high-quality SEBS:P3TMA films are obtained for all compositions (between 0.5 and 20 wt % P3TMA), their thickness and surface roughness increase with the nano-sized filler content. Moreover, the conducting particles are well integrated into the SEBS network with no evidence of aggregation or significant change in the mechanical properties of the composites. P3TMA, which forms encapsulated conductive domains within the polymeric matrix, improves the dielectric behavior of SEBS:P3TMA by increasing their dielectric constant with low dielectric losses and no current leakage. Thus, indicating the potential future application of these nanocomposites as elastomer actuators or high energy density capacitors.
The structural characterization of chiral nylon-3 derivative, poly (3-ethyl-3-phenyl-2- azetidinone) (PEPA) has been carried out using FTIR, thermal analysis, X-ray diffraction and electron microscopy. X-ray diffraction of power and fiber samples were analyzed together with electron diffraction patterns of single crystals obtained from isothermal crystallization in solution. Two different crystalline forms were found in accordance with DSC traces, FTIR spectra and X-ray diffraction diagrams. Electron microscopy corroborates the morphological and crystallographic differences between both crystalline forms. Molecular modeling was applied to characterize the two crystalline forms, which were related to different conformation and consequent space symmetry into the crystal unit cell
The structural and electronic properties of all-thiophene dendrimers and dendrons in solution have been evaluated using very different theoretical approaches based on quantum mechanical (QM) and hybrid QM/molecular mechanics (MM) methodologies: (i) calculations on minimum energy conformations using an implicit solvation model in combination with density functional theory (DFT) or time-dependent DFT (TD-DFT) methods; (ii) hybrid QM/MM calculations, in which the solute and solvent molecules are represented at the DFT level as point charges, respectively, on snapshots extracted from classical molecular dynamics (MD) simulations using explicit solvent molecules, and (iii) QM/MM-MD trajectories in which the solute is described at the DFT or TD-DFT level and the explicit solvent molecules are represented using classical force-fields. Calculations have been performed in dichloromethane, tetrahydrofuran and dimethylformamide. A comparison of the results obtained using the different approaches with the available experimental data indicates that the incorporation of effects associated with both the conformational dynamics of the dendrimer and the explicit solvent molecules is strictly necessary to satisfactorily reproduce the properties of the investigated systems. Accordingly, QM/MM-MD simulations are able to capture such effects providing a reliable description of electronic properties–conformational flexibility relationships in all-Th dendrimers.
Estrany, F.; Sanchez, M.; Borras, N.; Aleman, C.; Saborío, M. Reunión del Grupo de Electroquímica de la Real Sociedad Española de Química p. 112 Data de presentació: 2016-07-18 Presentació treball a congrés
Activación de la capacitancia de films de PEDOT por adición de nanopartículas de alúmina
Se han preparado nanocomposites de partículas de alúmina dispersa en una matriz de PEDOT electrogenerado sobre electrodo de acero a partir del monómero (3,4-etilendioxitiofeno ó EDOT) en medio acuoso con una suspensión partículas de alúmina, empleando LiClO4 como dopante. Se han generado capas simples y tricapas de PEDOT de microespesor, tanto puro como en forma de nanocomposite a partir de medios de EDOT y partículas de Al2O3 en proporciones 1:1 y 4:1, respectivamente.
Se ha verificado el comportamiento electroquímico (VC y carga-descarga galvanostática) de los films de composites obtenidos, así como la morfología superficial a micro- y a nano- escala con las técnicas SEM y AFM.
Los films de nanocomposites PEDOT/Al2O3 tienen una capacitancia específica mucho mayor que la de los de PEDOT puro, de forma similar a los films de nanocomposites de PEDOT/montmorillonita preparados en un trabajo anterior .
Es destacable que el mayor incremento de capacitancia específica se da en los nanocomposites generados con la menor proporción de partículas de alúmina, revelando que existe una composición óptima que maximiza la capacidad de almacenamiento de carga del film. El resultado es coherente con la morfología superficial de los films observada a micro- y nanoescala, que es más abierta (y por tanto permite una mayor movilidad interfacial de los iones) en el caso de los nanocomposites preparados a partir de la proporción. 4:1 EDOT/Al2O3.
Los autores agradecen al MCI, la financiación obtenida del Proyecto: MAT2012-34498.
 D. Aradilla, F Estrany, D. S. Azambuja et al. Eur. Polym. J. 46 (2010). 977-983.
Estrany, F.; Sanchez, M.; Borras, N.; Aleman, C.; Saborío, M. Reunión del Grupo de Electroquímica de la Real Sociedad Española de Química p. 116 Data de presentació: 2016-07-18 Presentació treball a congrés
Estudio de un sistema de tres capas de polímero conductor
para aplicaciones en baterías orgánicas
El propósito primordial de este proyecto, es el desarrollo de una batería orgánica usando electrodos de tres capas de polímeros conductores. Los monómeros de partida son el 3,4-polietilendioxitiofeno (EDOT) y el N-metilpirrol (NMPy), y cada capa de polímero se ha sintetizado sobre electrodo de acero inoxidable por electrodeposición cronoamperométrica, a 1,40 V, a partir de una disolución 10mM de cada monómero con 0,1 M de LiClO4 como electrolito. Se obtiene una estructura dopada, en general mucho más conductora que el polímero neutro.
Se han preparado films de PEDOT y de PNMPy puros, y también se ha ensayado la
preparación electroquímica del copolímero PEDOT/PNMPy. El PEDOT tiene una conductividad mucho mayor (con gran diferencia) que el PNMPy y que el copolímero, lo que nos ha llevó a proponer la estructura de un capacitor plano de dos capas-armaduras exteriores de PEDOT (como conductor) y una capa intermedia de PNMPy, o bien de copolímero (con la función de pseudo-dieléctrico), para obtener electrodos de gran capacidad redox de almacenamiento de carga.
Se prepararon baterías en forma de celdas galvánicas con electrodos tricapa, y se realizó el seguimiento de la fuerza electromotriz entre electrodos y la intensidad de corriente que atraviesa la celda, calculando también la potencia del sistema. Estas variables fueron estudiadas en circuito cerrado, siguiendo varios ciclos de carga y descarga electródica.
El estudio se complementó con el efecto del grosor de cada una de las tres capas de
los diferentes films, que conformaron la batería. Se estudió el efecto del puente salino y se varió el voltaje aplicado por la fuente de alimentación.
Se estudió la respuesta de los electrodos tricapa ante ciclos redox consecutivos en
celda de control, así como al someterlos a corriente constante a diferentes tiempos. Finamente se realizó también el estudio de su micro- y nanomorfología superficial mediante la técnica AFM.
Como conclusión es destacable la interesante respuesta eléctrica de la arriba indicada estructura tricapa tipo capacitor plano (armaduras conductoras – intermedio pseudodieléctrico).
Revilla-López, G.; Bertran, O.; Casanovas Salas, Jordi; Turon, P.; Puiggali, J.; Aleman, C. RSC advances Vol. 6, p. 69634-69640 DOI: 10.1039/c6ra10660a Data de publicació: 2016-07-13 Article en revista
Advanced Molecular Dynamics (MD) simulation protocols have been used to assess the ring puckering of cyclic D-ribose when the sugar is adsorbed on the most stable (0001) facet of calcium hydroxyapatite (HAp). In addition, sugar¿mineral interactions, which are crucial for transfection processes and prebiotic chemistry, have been studied for systems in which the Ca2+ ions of the above mentioned HAp facet were totally or partially replaced by Mg2+. The latter replacement is spatially and quantitatively limited and has been found to cause important alterations in the conformational behavior of D-ribose that are similar to those suffered in hairpin RNA from A to B helical structures. Accordingly, replacement of Ca2+ by Mg2+ has a dramatic effect on the functionality of the nucleic acid. These changes have been related to both the substitution site on the surface and the amount of ions. Our results show that when replacement by Mg2+ occurs in OH--coordinated Ca2+ ions, Mg2+¿D-ribose interactions are strong enough to prevent the interactions between the hydroxyl groups of the sugar and the remaining Ca2+ ions.
Electrochemical detection of glucose using simple polymeric electrodes without the assistance of enzymatic or inorganic catalysts (i.e. metals or metal oxides) has been issued a challenge to the scientific community. In this work we present the development of a potentiometric glucose sensor based on nanometric films of a very electroactive polythiophene derivative bearing a hydroxyl substituent per repeat unit. The sensor, which is enzyme free and does not require from additional catalytic nanoparticles, exhibits excellent tolerance against interferents, a low detection limit, and a deviation lower than 2% with respect to measures in human blood samples with commercial sensors. The excellent response of this highly electroactive polythiophene derivative, which exhibits a very simple chemical structure, has been attributed to the closeness between the hydroxyl substituents and the aromatic groups contained in the linear and rigid backbone. This particular chemical distribution favors the activation of the hydroxyl substituents, inducing their participation in the oxidation of glucose molecules. (C) 2016 Elsevier Ltd. All rights reserved.
Progress in the chemical sciences has formed the world we live in, both on a macroscopic and on a nanoscopic scale. The last decade witnessed the development of high performance materials that storage charge on many ways, from solar cells to fuel cells, from batteries to supercapacitors devices. One could argue that inorganic hybrid materials have played a central, starring role for the assemble of various electrochemical energy conversion systems. However, energy conversion systems fabricated from biopolymers has just emerged as new prospect. Here we summarize the main research highlights on the attactive employment of bio-hydrogels for the fabrication of either conductive electrolytes or electrodes for battery science and technology.
Electrocompatible interfaces formed by electroactive conducting polymers combined with biohydrogels towards sustainable solid-state supercapacitors
Maria M. Pérez-Madrigal,1,2,3 Francesc Estrany,3,4 Elaine Armelin,1,2,3 David Diaz-Diaz,1,* and Carlos Alemán2,3,*
1 Institut für Organische Chemie Fakultät für Chemie und Pharmazie Universität Regensburg Universitätsstr. 31 , 93053 Regensburg , Germany
2 Departament d’Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain
3 Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona E-08028, Spain
4 Departament d’Enginyeria Química, Escola Universitària d’Enginyeria Tècnica Industrial de Barcelona, Universitat Politècnica de Catalunya, Comte d’Urgell 187, 08036 Barcelona, Spain
* email@example.com and firstname.lastname@example.org
Electro compatible interfaces have been prepared with films of poly (3,4-ethylenedioxythiophene) (PEDOT) and biohidrogel, in order to prepare organic solid state electrochemical supercapacitors (OESCs). The electroactive surface of the conductive polymer film acts as an electrode and electrolyte biohidrogel acts as electron transfer, It has tried several hydrogels based on biomolecules (sodium alginate, ¿-carrageenan, chitosan and gelatin biohydrogels). In addition to performing tests morphological characterization by SEM microscopy, the degree of electrocompatibilidad of the prepared interface is characterized by assessing their electrical response to electrochemical techniques (Cyclic voltammetry and galvanostatic charge-discharge Assays), and the results have revealed that biohidrogel obtained based ¿-carrageenan is the most appropriate, because as the highest specific capacity and the highest electroestabilidad to consecutive redox cycles, added to a small leakage current and low self-discharging tendency. Good electrochemical results described, together with this biohidrogel has a good mechanical stability, is easy to prepare and no water loss, has become the ¿-carrageenan the best candidate for preparing OESCs. Based on these good properties, four OESC devices were connected in series and used to power on a red LED (Fig. 1), confirming that the system has clear expectations of being constitute a direct practical application.
Finally, it was tested adding polyaniline nanofibers dispersed in the matrix of biohidrogel, determining that the dispersed polyaniline is a redox additive which interacts with biomolecules to form the biohidrogel and changes the electrical response of the system. This allows to consider the improvement of future OESCs design with the ability to modulate the speed of charge and discharge of the device, using different concentrations of dispersed polyaniline.
Fig. 1. - LED powered using the system described
Authors are indebted to supports from MICINN and FEDER (MAT2012-34498)