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    Effect of the graft ratio on the properties of polythiophene-g-poly(ethylene glycol)  Open access

     Maione, Silvana; Fabregat Jove, Georgina; Del Valle Mendoza, Luis Javier; Bendrea, Anca Dana; Cianga, Luminita; Cianga, Ioan; Estrany Coda, Francisco; Aleman Llanso, Carlos Enrique
    Journal of polymer science. Part B, polymer physics
    Vol. 53, num. 4, p. 239-252
    DOI: 10.1002/polb.23617
    Date of publication: 2015-02-15
    Journal article

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    Graft copolymers formed by anchoring poly(ethylene glycol) (PEG) chains to conjugated polythiophene have been prepared by copolymerizing two compounds: unsubstituted -terthiophene (Th-3) and a thiophene-derived macromonomer having an -terthiophene conjugated sequence and one Th-3 bearing a PEG chain with molecular weight of 2000 as substitute at the 3-position of the central heterocycle (Th-3-PEG(2000)). The grafting ratio of the resulting copolymers (PTh3*-g-PEG), which were obtained using 75:25 and 50:50 Th-3-PEG(2000):Th-3 weight ratios, is significantly smaller than that of copolymers derived from polymerization of macromonomers consisting of a -pentathiophene sequence in which the central ring bears a PEG chain of M-w = 2000 (PTh5-g-PEG). The electroactivity and electrochemical stability of PTh3*-g-PEG is not only higher than that of PTh5-g-PEG but also higher than that of PTh3, the latter presenting a very compact structure that makes difficult the access and escape of dopant ions into the polymeric matrix during the redox processes. Furthermore, the optical -(*) lowest transition energy of PTh3*-g-PEG is lower than that of both PTh5-g-PEG and PTh3. These properties, combined with suitable wettability and roughness, result in an excellent behavior as bioactive platform of PTh3*-g-PEG copolymers, which are more biocompatible, in terms of cellular adhesion and proliferation, and electro-compatible than PTh5-g-PEG. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 239-252

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  • Synergistic approach to elucidate the incorporation of magnesium ions into hydroxyapatite

     Bertran Cànovas, Oscar; Del Valle Mendoza, Luis Javier; Revilla Lopez, Guillermo; Rivas Cañas, Manuel; Chaves Barboza, Gustavo Adolfo; Casas Becerra, M. Teresa; Casanovas Salas, Jordi; Turon Dols, Pau; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    Chemistry: a european journal
    Vol. 21, num. 6, p. 2537-2546
    DOI: 10.1002/chem.201405428
    Date of publication: 2015-02-02
    Journal article

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    Although the content of Mg2+ in hard tissues is very low (typically 1.5wt%), its incorporation into synthetic hydroxyapatite (HAp) particles and its role in the mineral's properties are still subject of intensive debate. A combined experimental-computational approach is used to answer many of the open questions. Mg2+-enriched HAp particles are prepared using different synthetic approaches and considering different concentrations of Mg2+ in the reaction medium. The composition, morphology and structure of the resulting particles are investigated using X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, scanning and transmission electron microscopies, FTIR, and wide-angle X-ray diffraction. After this scrutiny, the role of the Mg2+ in the first nucleation stages, before HAp formation, is investigated using atomistic molecular dynamics simulations. Saturated solutions are simulated with and without the presence of DNA, which has been recently used as a soft template in the biomineralization process. This synergistic investigation provides a complete picture of how Mg2+ ions affect the mineralization from the first stages onwards

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    Examining the compatibility of collagen and a polythiophene derivative for the preparation of bioactive platforms  Open access

     Soto Delgado, Jorge; Torras Costa, Juan; Del Valle Mendoza, Luis Javier; Estrany Coda, Francisco; Aleman Llanso, Carlos Enrique
    RSC Advances
    Vol. 5, num. 12, p. 9189-9203
    DOI: 10.1039/C4RA13812K
    Date of publication: 2015-01-09
    Journal article

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    Fundamental characteristics of bioactive platforms based on biocomposites of poly(3,4-ethylenedioxythiophene) (PEDOT) and collagen, named P(EDOT:CLG), have been examined using an experimental–computational approach. The protein affects both the morphology and electrochemical activity of PEDOT. Specifically, P(EDOT:CLG) shows spherical-like nodules that have been attributed to the collagen rod aggregates organized in phases separated from that of PEDOT. This phase separation results in a reduction of the ability to exchange charge reversibly, even though collagen stabilizes the PEDOT matrix from electrochemical degradation. On the other hand, viability assays indicate that the bioactivity of P(EDOT:CLG) is significantly higher than that of PEDOT in terms of cellular adhesion and proliferation. Thus, the biocomposite promotes the formation of 3D biostructures formed by the superposition of cellular monolayers, mimicking the growth of biological tissues. In order to gain microscopic information about the formation of specific interactions between PEDOT and collagen molecules in the biocomposite, quantum mechanical calculations on complexes formed by their building blocks have been performed in different environments (i.e. vacuum, chloroform and aqueous solution). Results evidence the important role played by non-conventional C–HO hydrogen bonds, which is consistent with previous findings on complexes involving DNA and dopamine. The environment affects considerably the binding energy, which decreases with increasing polarity of the environment. However, in all environments the repeating units of PEDOT form stronger interactions with L-hydroxyproline than with L-proline. On the other hand, intermolecular interaction patterns predicted using implicit and explicit solvation models present a remarkable agreement and have been identified by visualizing the reduced electron density gradient.

  • Advanced electrospun scaffolds based on biodegradable polylactide and poly(butylene succinate) for controlled drug delivery and tissue engineering  Open access

     Llorens Domenjo, Elena
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    La técnica de 'electrospinning' o electrohilado es un proceso de fabricación que utiliza un campo eléctrico para producir fibras a partir de disoluciones de polímeros. La acumulación de estas fibras conforma una matriz tri-dimensional o 'scaffold', y las fibras pueden ser preparadas en escala micro y nanométrica. Además, estas matrices o 'scaffold' se caracterizan por su gran superficie por unidad de masa, estructura porosa y propiedades mecánicas influenciadas por la orientación de las fibras. El 'electrospinning' es muy versátil y un gran número de polímeros con diferentes propiedades pueden ser procesados. Sin embargo, un gran número de variables pueden influir en las características de las fibras obtenidas, siendo variables propias del polímero (p.e., solubilidad, peso molecular, etc.) o relacionadas a los parámetros del proceso (voltaje, flujo, distancia colector-aguja). Estas matrices de fibras son atractivas para aplicaciones biomédicas como la ingeniería de tejidos y sistemas de liberación controlada de fármacos. En el último caso, es importante la carga de diferentes fármacos o drogas para su administración directa y localizada en el cuerpo humano. El objetivo de esta Tesis es el estudio de diferentes matrices constituidas por nano o microfibras electrohiladas. El desarrollo de este estudio se divide en cuatro bloques. En el primer bloque, matrices de fibras de poliláctico (PLA) fueron cargadas con diferentes moléculas con actividad antioxidante (vitamina B6 en sus formas de piridoxina y piridoxal, ácido p-cumárico y ácido cafeico). Se determinó la influencia de estas moléculas sobre las propiedades físicas, morfología, liberación in vitro y biocompatibilidad de dichas matrices. Además, se demostró la aplicación de estos nuevos materiales en la inhibición del daño oxidativo del ADN causado por iniciadores de radicales libres, y en consecuencia, estas matrices serían útiles para la purificación de ADN plasmídico o genómico. En el segundo bloque, las matrices de PLA fueron cargadas con dos o tres fármacos para obtener matrices multifuncionales en base a sus actividades. Con esta finalidad, moléculas con actividad antioxidante, anti-inflamatoria, y antimicrobiana fueron cargadas en las matrices para evitar los procesos de oxidación de diferentes biomoléculas (proteínas, ADN, etc.), evitar la inflamación local, y reducir el riesgo potencial de infección microbiana de las heridas, respectivamente. Estas matrices son especialmente interesantes debido a las sinergias y antagonismos que pueden ocurrir durante su liberación simultánea. En el tercer bloque, se prepararon matrices biodegradables a partir de polímeros no-electrohilables. Estos polímeros pueden presentar características particulares, como actividad bactericida, o actividad conductora/electroactividad. Matrices hibridas conformadas con diferentes ratios de PLA usado como polímero biodegradable y el poli(3-tiofeno metil acetato) como polímero electroactivo fueron preparadas y evaluadas. También se prepararon matrices de nanofibras de PLA cargadas con clorhidrato de polihexametilenbiguanida (PHMB) obteniéndose matrices biodegradables con actividad antibacteriana, y la liberación del PHMB fue altamente dependiente de la hidrófilicidad del medio.Finalmente, en el cuarto bloque, se prepararon matrices electrohiladas usando un polímero de sacrificio (polietilenglicol o PEG) que puede ser eliminado fácilmente por solubilización en medios acuosos. Tres preparaciones diferentes fueron evaluadas: a) Matrices constituidas por diferentes proporciones de PLA y PEG en las fibras, b) Matrices constituidas por fibras de PLA y fibras de PEG y, c) Matrices constituidas por fibras coaxiales con diferentes distribuciones de polímeros en el núcleo y la corteza de la fibra. La colonización celular en todas estas matrices fue mejorada. Estos tres procedimientos permitieron obtener matrices con diferentes comportamientos para la liberación de fármacos.

    Electrospinning is a manufacturing process that uses an electric field to produce fibers from a polymer solution. The accumulation of these fibers conform a three-dimensional fiber matrix or scaffold. Fibers can be prepared in a wide diameter range, namely from a micrometer to nanometer size. Furthermore, the fiber matrix or scaffold has a large surface per mass unit, a porous structure and mechanical properties influenced by the orientation of the fibers. The electrospinning technique is highly versatile and therefore a large number of polymers with different properties can be processed. However, a large number of variables can influence the characteristics of the resulting fibers, either because they are related to the polymer properties (e.g., solubility, molecular weight, etc.) or with the specific processing parameters (voltage, flow rate or distance tip-collector). Electrospun fiber matrices are attractive for biomedical applications as for example tissue engineering and drug delivery systems. In the last case, it is important the possibility to load the fibers with different drugs for their direct and localized administration into the human body. The goal of this Thesis is the study of different matrices constituted by electrospun micro- nanofibers and specifically four points have been considered. In the first one, polylactide electrospun scaffolds have been loaded with different molecules with antioxidant activity (i.e., vitamin B6 in pyridoxine and pyridoxal forms, p-coumaric acid and caffeic acid). The influence of these molecules on physical properties, morphology, in vitro release profiles and biocompatibility was determined. Furthermore, the application of these new materials for the inhibition of oxidative DNA damage caused by free radical initiators was demonstrated, and consequently, they appear appropriate candidates for purification of plasmidic or genomic DNA. In the second point, PLLA matrices loaded with two or three drugs were prepared in order to get a multifunctional activity. Thus, antioxidant, anti-inflammatory and antimicrobial molecules were considered in order to prevent chain oxidation processes in different biomolecules (proteins, DNA, etc.), avoid the subsequent local inflammation, and reduce the potential risk of microbial infection of wounds, respectively. These matrices are especially interesting due to the synergies and antagonisms that may occur during their simultaneous release. In the third point, the possibility of preparing biodegradable scaffolds from non electrospinable polymers has been considered. These polymers may have advantages like conductivity/electroactivity or bactericide activity. Hybrid scaffolds constituted by different ratios of polylactide as a biodegradable polymer and (poly(3-thiophene methyl acetate)) as electroactive polymer were evaluated. PLA nanofibers were also successfully loaded with polyhexamethylenebiguanide hydrochloride giving rise to 3D biodegradable scaffolds with a well proven antibacterial activity and a release that was highly dependent on the hydrophilicity of the medium. Finally electrospun scaffolds were obtained using a sacrificial polymer (e.g. poly(ethylene glycol) (PEG)) that could easily be subsequently removed by solubilization in aqueous media. Three approaches were evaluated: a) Preparation of scaffolds constituted by different ratios of PLA and PEG electrospun fibers, b) Preparation of scaffolds constituted by electrospun fibers with different PLA and PEG content; c) Preparation of scaffolds constituted by coaxial electrospun fibers with different core-shell polymer distributions. Cell colonization was in all cases favoured. The three procedures allowed preparing scaffolds with a differentiated drug release behavior.

    La técnica de 'electrospinning' o electrohilado es un proceso de fabricación que utiliza un campo eléctrico para producir fibras a partir de disoluciones de polímeros. La acumulación de estas fibras conforma una matriz tri-dimensional o 'scaffold', y las fibras pueden ser preparadas en escala micro y nanométrica. Además, estas matrices o 'scaffold' se caracterizan por su gran superficie por unidad de masa, estructura porosa y propiedades mecánicas influenciadas por la orientación de las fibras. El 'electrospinning' es muy versátil y un gran número de polímeros con diferentes propiedades pueden ser procesados. Sin embargo, un gran número de variables pueden influir en las características de las fibras obtenidas, siendo variables propias del polímero (p.e., solubilidad, peso molecular, etc.) o relacionadas a los parámetros del proceso (voltaje, flujo, distancia colector-aguja). Estas matrices de fibras son atractivas para aplicaciones biomédicas como la ingeniería de tejidos y sistemas de liberación controlada de fármacos. En el último caso, es importante la carga de diferentes fármacos o drogas para su administración directa y localizada en el cuerpo humano. El objetivo de esta Tesis es el estudio de diferentes matrices constituidas por nano o microfibras electrohiladas. El desarrollo de este estudio se divide en cuatro bloques. En el primer bloque, matrices de fibras de poliláctico (PLA) fueron cargadas con diferentes moléculas con actividad antioxidante (vitamina B6 en sus formas de piridoxina y piridoxal, ácido p-cumárico y ácido cafeico). Se determinó la influencia de estas moléculas sobre las propiedades físicas, morfología, liberación in vitro y biocompatibilidad de dichas matrices. Además, se demostró la aplicación de estos nuevos materiales en la inhibición del daño oxidativo del ADN causado por iniciadores de radicales libres, y en consecuencia, estas matrices serían útiles para la purificación de ADN plasmídico o genómico. En el segundo bloque, las matrices de PLA fueron cargadas con dos o tres fármacos para obtener matrices multifuncionales en base a sus actividades. Con esta finalidad, moléculas con actividad antioxidante, anti-inflamatoria, y antimicrobiana fueron cargadas en las matrices para evitar los procesos de oxidación de diferentes biomoléculas (proteínas, ADN, etc.), evitar la inflamación local, y reducir el riesgo potencial de infección microbiana de las heridas, respectivamente. Estas matrices son especialmente interesantes debido a las sinergias y antagonismos que pueden ocurrir durante su liberación simultánea. En el tercer bloque, se prepararon matrices biodegradables a partir de polímeros no-electrohilables. Estos polímeros pueden presentar características particulares, como actividad bactericida, o actividad conductora/electroactividad. Matrices hibridas conformadas con diferentes ratios de PLA usado como polímero biodegradable y el poli(3-tiofeno metil acetato) como polímero electroactivo fueron preparadas y evaluadas. También se prepararon matrices de nanofibras de PLA cargadas con clorhidrato de polihexametilenbiguanida (PHMB) obteniéndose matrices biodegradables con actividad antibacteriana, y la liberación del PHMB fue altamente dependiente de la hidrófilicidad del medio. Finalmente, en el cuarto bloque, se prepararon matrices electrohiladas usando un polímero de sacrificio (polietilenglicol o PEG) que puede ser eliminado fácilmente por solubilización en medios acuosos. Tres preparaciones diferentes fueron evaluadas: a) Matrices constituidas por diferentes proporciones de PLA y PEG en las fibras, b) Matrices constituidas por fibras de PLA y fibras de PEG y, c) Matrices constituidas por fibras coaxiales con diferentes distribuciones de polímeros en el núcleo y la corteza de la fibra. La colonización celular en todas estas matrices fue mejorada. Estos tres procedimientos permitieron obtener matrices con diferentes comportamientos para la liberación de fármacos.

  • Scaffolds constituted by mixed polylactide and poly(ethylene glycol) electrospun microfibers

     Llorens Domenjo, Elena; Bellmunt Montoya, Sergi; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge
    Journal of polymer research
    Vol. 21, num. 12
    DOI: 10.1007/s10965-014-0603-4
    Date of publication: 2014-11-12
    Journal article

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    Scaffolds comprising different ratios of poly(ethylene glycol) (PEG) and polylactide (PLA) electrospun fibers were prepared by using a single rotary collector. Electrospinning parameters and solution conditions were optimized to obtain continuous fibers and a homogeneous distribution of both polymers in the final scaffold. Short needle-collector distances allowed good overlapping of the two incident and independent jets. The composition of the scaffold was effectively tuned by varying the flow rate of the PLA solution. PEG and PLA fibers could be well distinguished in the scaffold because of their smooth and rough texture, respectively, and diameters in the nanometer and micrometer range. Greater sizes corresponded to polylactide and clearly depended on the flow rate. Drugs such as triclosan and polyhexamethylene biguanide hydrochloride, which have different hydrophilic/hydrophobic character and molecular size, were loaded into PLA microfibers by electrospinning. The high water solubility of PEG justified its use as a sacrificial polymer. Thus, it was possible to prepare scaffolds with tuned porosity (from 40 to 80 %) by water immersion of dual samples having different PEG content. Porosity greatly affected the release rate; specifically, a practically instantaneous or a sustained release was determined for triclosan in an appropriate medium. Drug loaded scaffolds had a clear bactericidal effect that was more effective for Gram-positive bacteria. Cell proliferation studies indicate that fibroblast colonization increased by 20-25 % in PLA/PEG scaffolds with high PEG contents compared to the control, whereas this effect was not observed for epithelial cells.

  • Preparation of micro-molded exfoliated clay nanocomposites by means of ultrasonic technology

     Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Del Valle Mendoza, Luis Javier; Aymami Bofarull, Juan; Olmo Osuna, Cristian; Puiggali Bellalta, Jorge
    Journal of polymer research
    Vol. 21, num. 11
    DOI: 10.1007/s10965-014-0584-3
    Date of publication: 2014-10-15
    Journal article

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    Ultrasound micro-molding technology has been tested as a new method to get polymer/clay nanocomposites. Biodegradable polylactide (PLA) and poly (nona-methylene azelate) (PE99) have been used as polymer matrices, whereas different silicate clays have been assayed. The new technology is able to get specimens without evidences of degradation during processing. Only the use of organo-modified clays could give rise to a slight molecular weight decrease when the poly (alkylene dicarboxylate) sample was considered. Ultrasonic micro-molding has revealed effective to get directly nanocomposites with the final form required for a selected application, a homogeneous clay distribution up to a load of 6 wt-% and more interestingly exfoliated structures without being necessary the use of a compatibilizer agent between the organic polymer and the inorganic silicate clay. Transmission electron micrographs and X-ray diffraction profiles revealed exfoliated structure when N757, C20A, C25A, and N848 clays were employed.; Crystallization behavior of exfoliated PLA nanocomposites was highly peculiar since clay particles had an antinucleating effect that decreased the overall crystallization rate respect to the neat polymer. In addition, the incorporation of layers into growing spherulites increased the crystal growth rate. A typical crystallization effect was on the contrary observed for nanocomposites derived from the poly (alkylene dicarboxylate) sample.

  • Polylactide micropieces loaded with antimicrobial agents by ultrasound micro-molding technology

     Del Valle Mendoza, Luis Javier; Olmo, Cristian; Rodríguez, Lorena; Puiggali Bellalta, Jorge
    Reunión del Grupo Especializado de Polímeros
    p. 248-249
    Presentation's date: 2014-09-09
    Presentation of work at congresses

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  • Preparation of micro-molded exfoliated clay nanocomposites by means of ultrasonic technology

     Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Del Valle Mendoza, Luis Javier; Aymami Bofarull, Juan; Puiggali Bellalta, Jorge
    Reunión del Grupo Especializado de Polímeros
    p. 220-221
    Presentation's date: 2014-09-08
    Presentation of work at congresses

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  • Electroactive polymers for the detection of morphine

     Cordova Mateo, Ester; Poater, Jordi; da Cruz Teixeira Dias, Bruno José; Bertran Cànovas, Oscar; Estrany Coda, Francisco; Del Valle Mendoza, Luis Javier; Solà, Miquel; Aleman Llanso, Carlos Enrique
    Journal of polymer research
    Vol. 21, num. 10, p. 1-13
    DOI: 10.1007/s10965-014-0565-6
    Date of publication: 2014-09-03
    Journal article

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    The interaction between morphine (MO), a very potent analgesic psychoactive drug, and five electroactive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-methylthiophene) (P3MT), polypyrrole (PPy), poly(N-methylpyrrole (PNMPy) and poly[N-(2-cyanoethyl)pyrrole] (PNCPy), has been examined using theoretical calculations on model complexes and voltammetric measures considering different pHs and incubation times. Quantum mechanical calculations in model polymers predict that the strength of the binding between the different polymers and morphine increases as follows: PEDOT < PNMPy < Py < < P3MT a parts per thousand PNCPy. The most relevant characteristic of P3MT is its ability to interact with morphine exclusively through non-directional interactions. On the other hand, the variations of the electroactivity and the anodic current at the reversal potential evidence that the voltammetric response towards the presence of MO is considerably higher for P3MT and PNCPy than that for the other polymers at both acid (P3MT > PNMPy) and neutral (P3MT a parts per thousand PNCPy) pHs. Energy decomposition analyses of the interaction of MO with different model polymers indicate that the stronger affinity of MO for P3MT and PNCPy as compared to PEDOT, PNMPy, and PPy is due to more favorable orbital interactions. These more stabilizing orbital interactions are the result of the larger charge transfer from MO to P3MT and PNCPy model polymers that takes place because of the higher stability of the single occupied molecular orbital (SOMO) of these model polymers. Therefore, to design polymers with a large capacity to detect MO we suggest looking at polymers with high electron affinity.

  • Anhydric maleic functionalization and polyethylene glycol grafting of lactide-co-trimethylene carbonate copolymers

     Diaz Andrade, Angelica Maria; Del Valle Mendoza, Luis Javier; Franco Garcia, Maria Lourdes; Sarasua, Jose-Ramon; Estrany Coda, Francisco; Puiggali Bellalta, Jorge
    Materials science and engineering C. Biomimetic and supramolecular systems
    Vol. 42, p. 517-528
    DOI: 10.1016/j.msec.2014.05.069
    Date of publication: 2014-09-01
    Journal article

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    Lactide and trimethylene carbonate copolymers were successfully grafted with polyethylene glycol via previous functionalization with maleic anhydride and using N,N'-diisopropylcarbodiimide as condensing agent. Maleinization led to moderate polymer degradation. Specifically, the weight average molecular weight decreased from 36,200 to 30,200 g/mol for the copolymer having 20 mol% of trimethylene carbonate units. Copolymers were characterized by differential scanning calorimetry, thermogravimetry and X-ray diffraction. Morphology of spherulites and lamellar crystals was evaluated with optical and atomic force microscopies, respectively. The studied copolymers were able to crystallize despite the randomness caused by the trimethylene carbonate units and the lateral groups. Contact angle measurements indicated that PEG grafted copolymers were more hydrophilic than parent copolymers. This feature justified that enzymatic degradation in lipase medium and proliferation of both epithelial-like and fibroblast-like cells were enhanced. Grafted copolymers were appropriate to prepare regular drug loaded microspheres by the oil-in-water emulsion method. Triclosan release from loaded microspheres was evaluated in two media. © 2014 Elsevier B.V.

  • Incorporation of a clot-binding peptide into polythiophene: properties of composites for biomedical applications

     Fabregat Jove, Georgina; da Cruz Teixeira Dias, Bruno José; Del Valle Mendoza, Luis Javier; Armelin Diggroc, Elaine; Estrany Coda, Francisco; Aleman Llanso, Carlos Enrique
    ACS applied materials and interfaces
    Vol. 6, num. 15, p. 11940-11954
    DOI: 10.1021/am503904h
    Date of publication: 2014-08-13
    Journal article

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    Biocomposites formed by a pentapeptide (CREKA), which recognizes clotted plasma proteins, entrapped into the poly(3,4-ethylenedioxythiophene) (PEDOT) matrix have been prepared using three very different procedures. X-ray photoelectron spectroscopy analyses indicate that PEDOT-CREKA films, prepared by chronoamperometry in basic aqueous solution (pH = 10.3) and deposited onto a PEDOT internal layer, present the higher concentration of peptide: one CREKA molecule per six polymer repeat units. The surface of this bilayered system shows numerous folds homogeneously distributed, which have been exhaustively characterized by scanning electron microscopy and atomic force microscopy. Indeed, the morphology and topography of such bilayered films is completely different from those of biocomposite-prepared acid aqueous and organic solutions as polymerization media. The impact of the entrapped peptide molecules in the electrochemical properties of the conducting polymer has been found to be practically negligible. In contrast, biocompatibility assays with two different cellular lines indicate that PEDOT-CREKA favors cellular proliferation, which has been attributed to the binding of the peptide to the fibrin molecules from the serum used as a supplement in the culture medium. The latter assumption has been corroborated examining the ability of PEDOT-CREKA to bind fibrin. The latter ability has been also used to explore an alternative strategy based on the treatment of PEDOT-CREKA with fibrin to promote cell attachment and growth. Overall, the results suggest that PEDOT-CREKA is appropriated for multiple biomedical applications combining the electrochemical properties of conducting polymer and the ability of the peptide to recognize and bind proteins.

  • Electro-biocompatibility of conjugates designed by chemical similarity

     Maione, Silvana; Fabregat Jove, Georgina; Del Valle Mendoza, Luis Javier; Ballano Ballano, María Gema; Cativiela, Carlos; Aleman Llanso, Carlos Enrique
    Journal of peptide science
    Vol. 20, num. 7, p. 537-546
    DOI: 10.1002/psc.2660
    Date of publication: 2014-07-01
    Journal article

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    The roughness and thickness of films formed by hybrid conjugates prepared by coupling poly(3,4-ethylenedioxythiophene) and synthetic amino acids bearing a 3,4-ethylenedioxythiophene group in the side chain have been significantly increased using a new synthetic approach. This procedure also provoked a more effective incorporation of the amino acid at the end of the polymer chains, as has been reflected by the electronic and electrochemical properties. Although the surface polarity of all these materials is similar to that of formamide, the hydrophilicity of the conjugates is higher than that of the conducting polymer. The surface energy of all the investigated systems is dominated by the dispersive component, even though the role played by the polar contribution is more important for the conjugates than for the conducting polymer. On the other hand, all the prepared materials behave as bioactive matrices. The electrochemical response of the conjugates coated with cells reflects the electro-compatibility of these two-component substrates. Thus, the ability to exchange charge reversibly of all conjugates increases considerably when they are coated with cellular monolayers, which has attributed to favorable interactions at the interface formed by the conjugate surface and the cellular monolayer. Copyright (c) 2014 European Peptide Society and John Wiley & Sons, Ltd.

  • Diarrhoea caused by rotavirus in a regional Peruvian hospital: Determination of circulating genotypes

     Weilg Espejo, Pablo; Orellana Peralta, Fiorella; Cornejo Pacheres, Hernán; Del Valle Mendoza, Luis Javier; Cornejo Tapia, Angela; Bazan Mayra, Jorge; Ruiz Blazquez, Joaquim; Del Valle Mendoza, Juana
    Transactions of the Royal Society of Tropical Medicine and Hygiene
    Vol. 108, num. 7, p. 425-430
    DOI: 10.1093/trstmh/tru059
    Date of publication: 2014-07
    Journal article

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    Background: Gastroenteritis caused by rotavirus is responsible for approximately 810 deaths per year in children under 5 years of age in Peru and emerging rotavirus genotypes have led to concerns regarding cross-protection by the vaccines available. Moreover, there are no reports on the molecular epidemiology of rotavirus diarrhoea in Peru. Methods: A total of 131 stool samples were obtained from children under 5 years hospitalised from January 2010 to December 2012 in the Hospital Regional de Cajamarca (Peru). ELISA and RT-PCR techniques were performed for rotavirus detection. G and P typing of rotavirus-positive samples were performed by semi-nested multiplex RT-PCR, and sequencing was performed to confirm the PCR results. Results: Of the 117 samples available, 22 (18.8%) tested positive for rotavirus by ELISA and 42 (35.9%) tested positive by RT-PCR. Among the G genotypes identified, G9 (35.7%; 15/42) and G12 (33.3%; 14/42) were the most prevalent, with the most common combination being G12/P[6] (23.8%; 10/42). Conclusions: A high prevalence of the G12/P[6] genotype was detected. It is known that this genotype is not covered by the current vaccines available. More in-depth studies are needed to determine the current rotavirus genotypes presents in Peru. © The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved.

  • Micro-molding with ultrasonic vibration energy: New method to disperse nanoclays in polymer matrices

     Planellas Oates, Marc; Sacristan, Matias; Rey, Lorena; Olmo, Cristian; Aymami Bofarull, Juan; Casas Becerra, M. Teresa; Del Valle Mendoza, Luis Javier; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Ultrasonics sonochemistry
    Vol. 21, num. 4, p. 1557-1569
    DOI: 10.1016/j.ultsonch.2013.12.027
    Date of publication: 2014-07-01
    Journal article

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    Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 001 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent. (C) 2014 Elsevier B.V. All rights reserved.

    Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 0 0 1 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent.

  • Molecular characterization of L-phenylalanine terminated poly(L-lactide) conjugates

     Murase Fernandez, Sara Keiko; Haspel, Nurit; Del Valle Mendoza, Luis Javier; Perpete, Eric; Nussinov, Ruth; Michaux, Catherine; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    RSC Advances
    num. 44, p. 23231-23241
    DOI: 10.1039/C4RA01534G
    Date of publication: 2014-05-15
    Journal article

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    Peptide–polymer conjugates made of poly(L-lactide) and L-phenylalanine or L,L-diphenylalanine (F–PLA and FF–PLA, respectively) have been synthesized by the ring-opening polymerization of L-lactide using the peptide fragment as an initiator. The structure of the conjugates was confirmed by 1H NMR, FT-IR, GPC, UV-Vis and CD. Molecular dynamics simulations have been used to identify both the conformational preferences of the FF–PLA conjugate in solution and the potential intramolecular interactions between the peptide and polymer blocks, while TD-DFT calculations have been applied to model the electronic transitions observed by the UV-Vis absorption spectroscopy. Results show that the polymer fragment prefers a random coil or a mix of helix/strand while the peptide fragment tends to have folded and helical conformations. Although the degree of interaction between the two fragments is slightly higher than that reported for other peptide–polymer conjugates, it is small enough to suggest that FF–PLA is a potential candidate to aggregate forming peptide-guided organizations via self-assembly. On the other hand, quantum mechanical calculations have allowed us to identify the p ¿ p* transition, which is typically observed in helical peptides and proteins, as well as the n ¿ p* transition along the N–C–O backbone.

  • Restricted puckering of mineralized RNA-like riboses

     Casanovas Salas, Jordi; Revilla López, Guillem; Bertran Cànovas, Oscar; Del Valle Mendoza, Luis Javier; Turon Dols, Pau; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    Journal of physical chemistry B
    Vol. 118, num. 19, p. 5075-5081
    DOI: 10.1021/jp501714q
    Date of publication: 2014-05-15
    Journal article

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    The pseudorotational motions of highly hydroxylated pentafuranose sugars in the free state and tethered to hydroxyapatite have been compared. The conformation pentafuranose ring remains restricted at the North region of the pseudorotational wheel, which is the one typically observed for nucleosides and nucleotides in the double helix A-RNA, when the phosphate-bearing sugar is anchored to the mineral surface. Results indicate that the severe restrictions imposed by the mineral are responsible of the double helix preservation when DNA and RNA are encapsulated in crystalline nanorods.

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    Gestió de projectes experimentals al laboratori  Open access

     Graells Sobre, Moises; Pérez Moya, Montserrat; Bernal Sánchez, Fernando; Boada Altarriba, Enric; Borras Cristofol, Nuria; Calvet Tarragona, Aurelio; Carral Mahia, Mª Eva; Dosta Parcerisa, Jordi; Espuña Camarasa, Antonio; López Mesas, Montserrat; de Miguel Gisbert, Leopoldo; Pujol, Carme; Sánchez, Margarita; Del Valle Mendoza, Luis Javier; Capon Garcia, Elisabeth; Nadal Cabezas, Sergi; Pérez, Mar; Yélamos, Ignacio; Bello, M. Camino; Ortega, Esther; San Antonio, Virginia
    Jornada d'Innovació Docent UPC
    p. 170-184
    Presentation's date: 2014-04-24
    Presentation of work at congresses

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  • Synthesis and characterization of poly(ester amides)s with a variable ratio of branched odd diamide units

     Murase Fernandez, Sara Keiko; Puiggali Bellalta, Jorge; Del Valle Mendoza, Luis Javier; Franco Garcia, Maria Lourdes
    Journal of applied polymer science
    Vol. 131, num. 7, p. 1-13
    DOI: 10.1002/app.40102
    Date of publication: 2014-04-05
    Journal article

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    The synthesis of a series of poly(ester amide)s constituted by glycolic acid, adipic acid, and different ratios of 1,3-pentanediamine and 1,5-pentanediamine units was studied and the derived copolymers were characterized. Thermal polycondensation between the potassium adipate salt and the appropriate ratio of N,N-bis(chloroacetyl)-1,3-pentanediamine and N,N-bis(chloroacetyl)-1,5-pentanediamine was proved to be effective, proceeded with high yield, and rendered samples with moderate molecular weight for carefully controlled competitive thermal degradation reactions. Physical properties were highly dependent on the final composition. In particular, crystallinity and thermal stability decreased with 1,3-pentanediamine unit content, that is, with the incorporation of lateral ethyl groups into the main chain. The presence of these units also changed solubility in solvents like methanol and degradability in a protease K enzymatic medium. Specifically, incorporation of 1,3-pentanediamine units led to a gradual increase in degradability. All poly(ester amide)s were able to establish intermolecular hydrogen bonding interactions, which in semicrystalline samples pointed to typical sheet structures of polyamides according to X-ray diffraction and infrared spectroscopic data. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40102.

    The synthesis of a series of poly(ester amide)s constituted by glycolic acid, adipic acid, and different ratios of 1,3-pentanediamine and 1,5-pentanediamine units was studied and the derived copolymers were characterized. Thermal polycondensation between the potassium adipate salt and the appropriate ratio of N,N-bis(chloroacetyl)-1,3-pentanediamine and N,N-bis(chloroacetyl)-1,5-pentanediamine was proved to be effective, proceeded with high yield, and rendered samples with moderate molecular weight for carefully controlled competitive thermal degradation reactions. Physical properties were highly dependent on the final composition. In particular, crystallinity and thermal stability decreased with 1,3-pentanediamine unit content, that is, with the incorporation of lateral ethyl groups into the main chain. The presence of these units also changed solubility in solvents like methanol and degradability in a protease K enzymatic medium. Specifically, incorporation of 1,3-pentanediamine units led to a gradual increase in degradability. All poly(ester amide)s were able to establish intermolecular hydrogen bonding interactions, which in semicrystalline samples pointed to typical sheet structures of polyamides according to X-ray diffraction and infrared spectroscopic data.

  • Inhibition of radical-induced oxidative DNA damage by antioxidants loaded in electrospun polylactide nanofibers

     Llorens Domenjo, Elena; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge
    Macromolecular research
    Vol. 22, num. 4, p. 388-396
    DOI: 10.1007/s13233-014-2053-6
    Date of publication: 2014-04-01
    Journal article

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    Polylactide (PLA) nanofibers loaded with antioxidants, i.e. vitamin B-6 or pyridoxine (PN) and its analogue pyridoxal (PL), and with hydroxycinnamic acids, i.e. p-coumaric acid (CUM) and caffeic acid (CAF), were prepared by the electrospinning technique. The control consisted of nanofibers loaded with trolox (TRX). Experimentally, these new materials were tested on the inhibition of oxidative DNA damage caused by free radicals initiated by 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH). This damage was assessed in vitro and in vivo by measuring the conversion of supercoiled pUC19 plasmid DNA to open circular and linear forms. It was found that these antioxidants, in solution, could significantly inhibit oxidative DNA damage, and that the antioxidants loaded in the PLA nanofibers maintained in vitro and in vivo their protective role against oxidative DNA damage. Thus, electrospun mats derived from PLA nanofibers loaded with the considered compounds have the capacity to protect DNA against oxidative damage, and appear interesting, for their use in the purification of plasmidic or genomic DNA.

  • Diagnosis of Carrion’s disease by direct blood PCR in thin blood smear negative samples

     Del Valle Mendoza, Juana; Silva Caso, Wilmer; Tinco Valdez, Carmen; Pons, Maria J.; Del Valle Mendoza, Luis Javier; Casabona Oré, Veronica; Champin Michelena, Denissse; Bazan Mayra, Jorge; Zavalea Gavidea, Víctor; Vargas, Martha; Ruiz Blazquez, Joaquim
    PLoS one
    Vol. 9, num. 3, p. e92283-
    DOI: 10.1371/journal.pone.0092283
    Date of publication: 2014-03-20
    Journal article

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    Bartonella bacilliformis is the etiologic agent of Carrion’s disease. This disease has two well established phases, the most relevant being the so called Oroya Fever, in which B. bacilliformis infect the erythrocytes resulting in severe anemia and transient immunosuppression, with a high lethality in the absence of adequate antibiotic treatment. The presence of B. bacilliformis was studied in 113 blood samples suspected of Carrion’s disease based on clinical criteria, despite the absence of a positive thin blood smear, by two different PCR techniques (using Bartonella-specific and universal 16S rRNA gene primers), and by bacterial culture. The specific 16S rRNA gene primers revealed the presence of 21 B. bacilliformis and 1 Bartonella elizabethae, while universal primers showed both the presence of 3 coinfections in which a concomitant pathogen was detected plus Bartonella, in addition to the presence of infections by other microorganisms such as Agrobacterium or Bacillus firmus. These data support the need to implement molecular tools to diagnose Carrion’s disease.

  • Scaffolds with tuneable hydrophilicity from electrospun microfibers of polylactide and poly(ethylene glycol) mixtures: morphology, drug release behavior, and biocompatibility

     Llorens Domenjo, Elena; Del Valle Mendoza, Luis Javier; Ferran, Ricard; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Journal of polymer research
    Vol. 21, num. 2, p. 360-1-360-15
    DOI: 10.1007/s10965-014-0360-4
    Date of publication: 2014-01-29
    Journal article

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    Electrospun mats were obtained from different mixtures of polylactide (PLA) and poly(ethylene glycol) (PEG). Processing conditions were optimized for all compositions and the resulting micro/nanofiber morphologies (i.e., diameter size and surface texture) were characterized by scanning electron microscopy (SEM). NMR and FTIR spectroscopies were employed to verify the final compositions, and thermal properties were evaluated by DSC and TGA. XPS spectroscopy revealed that PEG was mainly deposited on the surfaces of the electrospun micro/nanofibers, leading to smooth textures. Interestingly, PLA/PEG scaffold solubility in ethanol was very different to that in water, since a significant amount of PEG was effectively retained in the PLA matrix after immersion in ethanol whereas only a low level of PEG was retained in the PLA matrix after immersion in water. The hydrophilicities of the scaffolds obtained from PLA/PEG mixtures were consequently higher than that of the PLA, even after exposure to water. As PEG can be used as a sacrificial polymer due to its high solubility in water, it was possible to increase the porosity of PLA/PEG scaffolds. PLA/PEG scaffolds loaded with triclosan (TCS) had very different release profiles in hydrophilic (e. g., PBS) and hydrophobic (e. g., Srensen/ethanol 30: 70v/v) media, while differences were small between scaffolds with different PLA/PEG ratios. TCS-loaded scaffolds exhibited good antibacterial properties for all compositions and allowed the adhesion of epithelial cells (i.e., MDCK and VERO). Significant differences in cell proliferation were found between unloaded and TCS-loaded scaffolds due to the clear improvement in cell colonization observed with increasing PEG content.

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    Mineralization of DNA into nanoparticles of hydroxyapatite  Open access

     Bertran Cànovas, Oscar; Del Valle Mendoza, Luis Javier; Revilla Lopez, Guillermo; Chaves Barboza, Gustavo Adolfo; Cardus Andreu, Lluis; Casas Becerra, M. Teresa; Casanovas Salas, Jordi; Turon Dols, Pau; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    Dalton transactions
    Vol. 43, num. 1, p. 317-327
    DOI: 10.1039/c3dt52112e
    Date of publication: 2014-01-07
    Journal article

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    Encapsulation of DNA into hydroxyapatite (HAp) has been investigated using a rational approach that involves computer simulation and experimental techniques. The temporal evolution of the radial distribution functions derived from atomistic molecular dynamics simulations of Ca2+, PO 4 3- and OH--containing aqueous solutions in the presence and absence of B-DNA has been used to conclude that the backbone of the double helix acts as a template for HAp growth. More specifically, results reveal the formation of calcium phosphate clusters at the first stages of the simulations, which subsequently re-organize to nucleate HAp. This effect is produced in the absence and, especially, presence, of DNA indicating that the biomolecules do not inhibit but even promote mineral growth. Furthermore, computer simulations suggest that the diffusion of the OH- anions through the inorganic solution is the limiting step for the nucleation of the biomineral. Nanocapsules and crystalline nanorods of HAp containing DNA molecules inside have been prepared by mixing solutions containing Ca 2+ and PO4 3- ions with fish sperm DNA at high pH. The dimensions and morphology of such nanostructures have been examined by transmission electron microscopy, while the characterization of the biomineral has been focused on the identification of DNA inside HAp using infrared, X-ray photoelectron and UV-vis spectroscopies, as well as gel electrophoresis. The biominerals reported in this work are important for biomedical applications requiring the protection of DNA from aggressive environmental conditions. © 2014 The Royal Society of Chemistry.

    Encapsulation of DNA into hydroxyapatite (HAp) has been investigated using a rational approach that involves computer simulation and experimental techniques. The temporal evolution of the radial distribution functions derived from atomistic molecular dynamics simulations of Ca2+, PO4 3− and OH−-containing aqueous solutions in the presence and absence of B-DNA has been used to conclude that the backbone of the double helix acts as a template for HAp growth. More specifically, results reveal the formation of calcium phosphate clusters at the first stages of the simulations, which subsequently reorganize to nucleate HAp. This effect is produced in the absence and, especially, presence, of DNA indicating that the biomolecules do not inhibit but even promote mineral growth. Furthermore, computer simulations suggest that the diffusion of the OH− anions through the inorganic solution is the limiting step for the nucleation of the biomineral. Nanocapsules and crystalline nanorods of HAp containing DNA molecules inside have been prepared by mixing solutions containing Ca2+ and PO4 3− ions with fish sperm DNA at high pH. The dimensions and morphology of such nanostructures have been examined by transmission electron microscopy, while the characterization of the biomineral has been focused on the identification of DNA inside HAp using infrared, X-ray photoelectron and UV-vis spectroscopies, as well as gel electrophoresis. The biominerals reported in this work are important for biomedical applications requiring the protection of DNA from aggressive environmental conditions

  • Hybrid nanofibers from biodegradable polylactide and polythiophene for scaffolds

     Llorens Domenjo, Elena; Perez Madrigal, Maria Del Mar; Armelin Diggroc, Elaine; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    RSC Advances
    Vol. 4, num. 29, p. 15245-15255
    DOI: 10.1039/c3ra42829j
    Date of publication: 2014-01-01
    Journal article

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    Hybrid scaffolds constituted of polylactide (PLA) as a biodegradable polymer and poly(3-thiophene methyl acetate) (P3TMA) as an electroactive polymer were prepared and studied. Both polymers had a similar solubility and consequently could be easily electrospun using a common solvent. Electrospinning operational parameters were optimized to get continuous micro/nanofibers with a homogeneous diameter that ranged between 600 and 900 nm depending on the PLA-P3TMA ratio. Electrospinning was only effective when the P3TMA content was at maximum 50 wt%. The incorporation of P3TMA slightly decreased the fibre diameter, led to smoother fibre surfaces and gave rise to some heterogeneous clusters inside the fibers. PLA was highly oriented inside the electrospun fibers and able to easily cold crystallize by heating. Thermal degradation was not highly influenced by the presence of P3TMA, although the onset temperature slightly increased since the first decomposition step of PLA was prevented. New scaffolds had promising electrochemical properties and even provided a good substrate for cell adhesion and cell proliferation. Therefore, these hybrid materials are suitable to improve the cellular response towards physiological processes.

  • Poly(butylene azelate-co-butylene succinate) copolymers: Crystalline morphologies and degradation

     Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Estrany Coda, Francisco; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge
    Polymer degradation and stability
    Vol. 99, num. 1, p. 80-91
    DOI: 10.1016/j.polymdegradstab.2013.11.022
    Date of publication: 2014-01
    Journal article

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    Random copolymers derived from 1,4-butanediol and two dicarboxylic units differing in the parity of the number of methylene groups and length of the polymethylene sequence (i.e. succinic and azelaic acids) were studied in terms of thermal properties, crystalline structure and morphology, crystallization kinetics and biodegradability. All samples were semicrystalline and their thermal properties varied in a wide temperature range. Copolymers crystallized according to the monoclinic a-form of polybutylene succinate and the orthorhombic structure postulated for polybutylene azelate depending on the predominant dicarboxylate unit. The behavior of the copolymer with an intermediate composition was complex due to strong dependence of the predominant crystalline form on crystallization and processing conditions. Interestingly, crystallization into the azelate structure was favored when samples were rapidly cooled from the melt, resulting in an unexpected increase in the degree of crystallinity. Spherulitic morphologies were clearly different (i.e. ringed spherulites and axialites) depending on the preferential crystalline structure. Enzymatic degradability of the two homopolyesters was highly different and could be enhanced by incorporation of comonomer units. Preferential enzymatic attack on amorphous regions highlighted the spherulitic morphologies of copolymers having well developed, distinctive ringed structures. © 2013 Elsevier Ltd. All rights reserved.

    Random copolymers derived from 1,4-butanediol and two dicarboxylic units differing in the parity of the number of methylene groups and length of the polymethylene sequence (i.e. succinic and azelaic acids) were studied in terms of thermal properties, crystalline structure and morphology, crystallization kinetics and biodegradability. All samples were semicrystalline and their thermal properties varied in a wide temperature range. Copolymers crystallized according to the monoclinic α-form of polybutylene succinate and the orthorhombic structure postulated for polybutylene azelate depending on the predominant dicarboxylate unit. The behavior of the copolymer with an intermediate composition was complex due to strong dependence of the predominant crystalline form on crystallization and processing conditions. Interestingly, crystallization into the azelate structure was favored when samples were rapidly cooled from the melt, resulting in an unexpected increase in the degree of crystallinity. Spherulitic morphologies were clearly different (i.e. ringed spherulites and axialites) depending on the preferential crystalline structure. Enzymatic degradability of the two homopolyesters was highly different and could be enhanced by incorporation of comonomer units. Preferential enzymatic attack on amorphous regions highlighted the spherulitic morphologies of copolymers having well developed, distinctive ringed structures.

  • Analysis of quinolone-resistance in commensal and diarrheagenic escherichia coli isolates from infants in lima, Peru

     Pons, María Jesús; Mosquito, Susan; Gomes, Cláudia; Del Valle Mendoza, Luis Javier; Ochoa, Theresa J.; Ruiz Blazquez, Joaquim
    Transactions of the Royal Society of Tropical Medicine and Hygiene
    Vol. 108, num. 1, p. 22-28
    DOI: 10.1093/trstmh/trt106
    Date of publication: 2014-01
    Journal article

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    Background: Antibiotic resistance is an increasing problem, particularly in countries where antibiotic use is frequently not controlled. The aim of this study was to analyse the prevalence of the molecular mechanisms of quinolone-resistance in E. coli isolated from faeces of healthy Peruvian children or those presenting diarrhoea. Methods: The presence of target mutations, transferable quinolone-resistance mechanisms and the role of Phe-Arg-b-Naphtylamyde inhibitible efflux pumps were studied in 96 Escherichia coli (46 diarrheogenic and 50 non-diarrheogenic) isolates exhibiting resistance or diminished susceptibility to quinolones. Results: The most resistant phenotype, NalR and CipR, was most frequently present in isolates of healthy children. The distribution of quinolone resistance mechanisms between diarrheogenic (DEC) and commensal (non DEC) isolates was equitable, although the aac(6')Ib-cr gene was mainly detected in DEC isolates: 17 (34%) vs non DEC isolates nine (20%). QnrB was present in five (10%) DEC vs three (6%) non DEC isolates. Conclusions: Point mutations in gyrA and parC genes play a relevant role in quinolone resistance acquisition and highlight the role of efflux pumps also. This study provides knowledge about the molecular mechanisms involved in quinolone resistance in isolates in a non exposed population under high community antibiotic pressure. © The Author 2013. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.All rights reserved.

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    DNA adsorbed on hydroxyapatite surfaces  Open access

     Del Valle Mendoza, Luis Javier; Bertran Cànovas, Oscar; Chaves Barboza, Gustavo Adolfo; Revilla Lopez, Guillermo; Rivas Cañas, Manuel; Casanovas Muñoz, Jordi; Turon Dols, Pau; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique; Casas, Maria Teresa
    Journal of materials chemistry B
    Vol. 2, num. 40, p. 6953-6966
    DOI: 10.1039/c4tb01184h
    Date of publication: 2014-01-01
    Journal article

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    Hydroxyapatite (HAp) particles with very different surface charges and compositions (i.e. different Ca/P and CO32-/PO43- ratios) have been obtained by varying the experimental conditions used during the chemical precipitation process. The DNA adsorption capacity and protection imparted against the attack of nucleases of HAp particles have been proved to depend on the surface charge while the buffering capacity is affected by the chemical composition. On the basis of both the surface charge and the crystallinity, the predominant planes at the surfaces of HAp particles have been identified. Atomistic molecular dynamics simulations of surfaces constructed with these planes (i.e. (001) and the two terminations of (010)) with the adsorbed B-DNA double helix have been performed to get microscopic understanding of the influence of the mineral in the biomolecule structure and the interaction energies. The results indicate that the DNA secondary structure is perfectly preserved on the (001) surface, this stability being accompanied by an attractive binding energy. In contrast, the (010) surface with PO43-, OH- and Ca2+ ions in the termination induces significant local and global deformations in the double helix, repulsive OH-(HAp)/PO43- (DNA) interactions provoking the desorption of the biomolecule. Finally, although the termination of the (010) surface with PO43- and Ca2+ ions also deforms the double helix, it forms very strong attractive interactions with the biomolecule. These binding characteristics are in excellent agreement with the DNA adsorption and protection abilities experimentally determined for the HAp samples. Finally, the surface charge has been found less decisive than the chemical composition in the efficacy of the transfection process.

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    Nanomembranes and nanofibers from biodegradable conducting polymers  Open access

     Llorens Domenjo, Elena; Armelin Diggroc, Elaine; Perez Madrigal, Maria Del Mar; Del Valle Mendoza, Luis Javier; Aleman Llanso, Carlos Enrique; Puiggali Bellalta, Jorge
    Polymers
    Vol. 5, num. 3, p. 1115-1157
    DOI: 10.3390/polym5031115
    Date of publication: 2013-09-01
    Journal article

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    This review provides a current status report of the field concerning preparation of fibrous mats based on biodegradable (e. g., aliphatic polyesters such as polylactide or polycaprolactone) and conducting polymers (e. g., polyaniline, polypirrole or polythiophenes). These materials have potential biomedical applications (e. g., tissue engineering or drug delivery systems) and can be combined to get free-standing nanomembranes and nanofibers that retain the better properties of their corresponding individual components. Systems based on biodegradable and conducting polymers constitute nowadays one of the most promising solutions to develop advanced materials enable to cover aspects like local stimulation of desired tissue, time controlled drug release and stimulation of either the proliferation or differentiation of various cell types. The first sections of the review are focused on a general overview of conducting and biodegradable polymers most usually employed and the explanation of the most suitable techniques for preparing nanofibers and nanomembranes (i.e., electrospinning and spin coating). Following sections are organized according to the base conducting polymer (e. g., Sections 4-6 describe hybrid systems having aniline, pyrrole and thiophene units, respectively). Each one of these sections includes specific subsections dealing with applications in a nanofiber or nanomembrane form. Finally, miscellaneous systems and concluding remarks are given in the two last sections.

  • Electroactive nanofibers for drug release devices and cellular substrates

     Perez Madrigal, Maria Del Mar; Llorens Domenjo, Elena; Armelin Diggroc, Elaine; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique
    International Conference on Materials Chemistry
    p. P029
    Presentation's date: 2013-07-08
    Presentation of work at congresses

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  • Factors affecting caregivers' use of antibiotics available without a prescription in Peru

     Ecker, Lucie; Ochoa, Theresa J.; Vargas, Martha; Del Valle Mendoza, Luis Javier; Ruiz Blazquez, Joaquim
    Pediatrics
    Vol. 131, num. 6, p. e1771-e1779
    DOI: 10.1542/peds.2012-1970
    Date of publication: 2013-06
    Journal article

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    OBJECTIVE: To determine factors that affect caregivers' decisions about antibiotic use in children in settings where antibiotics are available without prescription. METHODS: In a house-to-house survey, 1200 caregivers in 3 periurban districts of Lima, Peru, were asked about antibiotic use in young children. RESULTS: In this sample, 87.2% of children aged ,5 years had received an antibiotic drug in their lives; 70.3% had received antibiotics before 1 year of age, and 98.8% of those had been prescribed by a physician. Given hypothetical cases of common cold and nondysenteric diarrhea, caregivers would seek medical advice in 76.4% and 87.1%, respectively, and 84.6% of caregivers said they respected medical decisions even if an antibiotic was not prescribed. Caregivers with high school-level education accepted 80% more medical decisions of not using an antibiotic and used fewer pharmacist-recommended antibiotics. For each additional year of life, the risk of self-medicated antibiotic use and the use of pharmacistrecommended antibiotics increased in 30%. (OR: 1.3, 95% CI: 1.1-1.4, P = .001 and OR: 1.3, 95% CI: 1.2-1.5, P < .001, respectively). Caregivers respected a medical decision of not prescribing an antibiotic 5 times more when physicians had explained the reason for their advice (OR: 5.0, 95% CI: 3.2-7.8, P < .001). CONCLUSIONS: Prescribed antibiotic use in these young children is common. Even if they are available without prescription, caregivers usually comply with medical advice and follow physicians' recommendations when antibiotics are not prescribed. Improving physician prescribing habits could reduce irrational antibiotic use, decreasing future caregiver-driven misuse.

  • Smart electroactive hybrid materials as platforms for tissue engineering

     Armelin Diggroc, Elaine; Fabregat Jove, Georgina; Bendrea, Anca-Dana; Ballano Ballano, María Gema; Cianga, Luminita; Del Valle Mendoza, Luis Javier; Cativiela, Carlos; Cianga, Ioan; Aleman Llanso, Carlos Enrique
    Frontiers in Polymer Science
    p. P1-175
    Presentation's date: 2013-05-21
    Presentation of work at congresses

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  • Amphiphilic polythiophenes- A multifunctional biomedical platform

     Bendrea, Anca-Dana; Cianga, Luminita; Fabregat Jove, Georgina; Del Valle Mendoza, Luis Javier; Aleman Llanso, Carlos Enrique; Timur, Suna; Cianga, Ioan
    Conference on Colloid and Surface Chemistry
    Presentation's date: 2013-05-09
    Presentation of work at congresses

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  • New poly(ester amide)s containing glycolic acid, adipic acid and cadaverine or 1,6-hexanediamine units. Scaffolds with anti-inflammatory properties

     Murase Fernandez, Sara Keiko; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge
    Multifunctional, Hybrid and Nanomaterials
    Presentation's date: 2013-03-03
    Presentation of work at congresses

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  • Hybrid materials consisting of an all-conjugated polythiophene backbone and grafted hydrophilic poly(ethylene glycol) chains

     Bendrea, Anca Dana; Fabregat Jove, Georgina; Cianga, Luminita; Estrany Coda, Francisco; Del Valle Mendoza, Luis Javier; Cianga, Ioan; Aleman Llanso, Carlos Enrique
    Polymer Chemistry
    Vol. 4, num. 9, p. 2709-2723
    DOI: 10.1039/C3PY00029J
    Date of publication: 2013-03-01
    Journal article

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    Organic hybrid materials consisting of an all-conjugated polythiophene backbone and well-defined poly(ethylene glycol) (PEG) grafted chains have been prepared by anodic polymerization of chemically synthesized macromonomers. The latter consist of a pentathiophene sequence in which the central ring bears a PEG chain with Mw = 1000 or 2000 at the 3-position. The influence of the polymerization potential, the length of the PEG branches and the dopant agent on the structure and properties of the graft copolymers has been examined. The chemical structure of the grafted materials has been corroborated by FTIR and X-ray photoelectron spectroscopies. Scanning electron microscopy and atomic force microscopy studies reveal that the morphology and topography of these materials are influenced by the above mentioned factors, even though homogeneous films showing a compact distribution of nanoaggregates, very flat surfaces (i.e. roughness < 15 Å) and nanometric thickness (i.e. 100–500 nm) were obtained in all cases. Cyclic voltammetry assays have been used to determine the presence of charged species, the electroactivity, the electrostability and the formation of cross-links. The electrochemical stability of the copolymer with grafted PEG chains of Mw = 1000 has been found to increase with the number of consecutive oxidation–reduction cycles (self-electrostabilizing behavior). Finally, a preliminary investigation into the applicability of these hybrid materials as active surfaces for the selective adsorption of proteins is presented.

  • Examining the formation of specific interactions between poly(3,4-ethylenedioxythiophene) and nucleotide bases

     Zanuy Gomara, David; Teixeira Dias, Fábio; Del Valle Mendoza, Luis Javier; Poater, Jordi; Solà, Miquel; Aleman Llanso, Carlos Enrique
    RSC Advances
    Vol. 3, num. 8, p. 2639-2649
    DOI: 10.1039/c2ra22640e
    Date of publication: 2013-02-28
    Journal article

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    he formation of specific interaction between poly(3,4-ethylenedioxythiophene) (PEDOT) and adenine (A), cytosine (C) and thymine (T) single stranded homonucleotides has been investigated, complementing our previous investigation on complexes formed by PEDOT and guanine (G) homonucleotide (B. Teixeira-Dias et al, Soft Matter, 2011, 7, 9922–9932). Results derived from UV-vis and FTIR spectroscopy suggest that A and, especially, C homonucleotides form adducts dominated by non-specific electrostatic interactions, while complexes with T homonucleotides show a behavior that differ from those found for A-, C- and G-containing systems. Results provided by molecular dynamics simulations were consistent with these experimental observations. Thus, specific interactions are much less abundant in A- and C-containing complexes than in those involving G. Moreover, simulations allowed us to detect a structural re-organization in the T-containing complexes, which occurs after their initial formation. This has been attributed to the optimization of electrostatic interactions rather than to the formation of new specific interactions, as was previously found in complexes with G. From the analysis of the interaction of the different nucleotides with an EDOT molecule it is concluded that the most stabilizing specific interaction corresponds to the formation of N-HOEDOT hydrogen bonds. Stabilization comes from electrostatic interactions, although the covalent contribution is non negligible.

  • Bioactive nanomembranes of semiconductor polythiophene and thermoplastic polyurethane: Thermal, nanostructural and nanomechanical properties

     Perez Madrigal, Maria Del Mar; Giannotti, Marina I.; Oncins Marco, Gerard; Franco Garcia, Maria Lourdes; Armelin Diggroc, Elaine; Puiggali Bellalta, Jorge; Sanz Carrasco, Fausto; Del Valle Mendoza, Luis Javier; Aleman Llanso, Carlos Enrique
    Polymer Chemistry
    Vol. 4, num. 3, p. 568-583
    DOI: 10.1039/c2py20654d
    Date of publication: 2013-02-07
    Journal article

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    Polythiophene-g-poly(ethylene glycol) graft copolymers for electroactive scaffolds  Open access

     Bendrea, Anca Dana; Fabregat Jove, Georgina; Torras Costa, Juan; Maione, Silvana; Cianga, Ioan; Del Valle Mendoza, Luis Javier; Cianga, Luminita; Aleman Llanso, Carlos Enrique
    Journal of materials chemistry B
    p. 4135-4145
    DOI: 10.1039/C3TB20679C
    Date of publication: 2013
    Journal article

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    The properties, microscopic organization and behavior as the cellular matrix of an all-conjugated polythiophene backbone (PTh) and well-defined poly(ethylene glycol) (PEG) grafted chains have been investigated using different experimental techniques and molecular dynamic simulations. UV-vis spectroscopy has been used to determine the optical band gap, which has been found to vary between 2.25 and 2.9 eV depending on the length of the PEG chains and the chemical nature of the dopant anion, and to detect polaron ¿ bipolaron transitions between band gap states. The two graft copolymers have been found to be excellent cellular matrices, their behavior being remarkably better than that found for other biocompatible polythiophene derivatives [e.g. poly(3,4-ethylenedioxythiophene)]. This is fully consistent with the hydrophilicity of the copolymers, which increases with the molecular weight of the PEG chains, and the molecular organization predicted by atomistic molecular dynamics simulations. Graft copolymers tethered to the surface tend to form biphasic structures in solvated environments (i.e. extended PTh and PEG fragments are perpendicular and parallel to the surface, respectively) while they collapse onto the surface in desolvated environments. Furthermore, the electrochemical activity and the maximum of current density are remarkably higher for samples coated with cells than for uncoated samples, suggesting multiple biotechnological applications in which the transmission with cells is carried out at the electrochemical level.

    The properties, microscopic organization and behavior as the cellular matrix of an all-conjugated polythiophene backbone (PTh) and well-de fi ned poly(ethylene glycol) (PEG) grafted chains have been investigated using di ff erent experimental techniques and molecular dynamic simulations. UV-vis spectroscopy has been used to determine the optical band gap, which has been found to vary between 2.25 and 2.9 eV depending on the length of the PEG chains and the chemical nature of the dopant anion, and to detect polaron / bipolaron transitions between band gap states. The two graft copolymers have been found to be excellent cellular matrices, their behavior being remarkably better than that found for other biocompatible polythiophene derivatives [ e.g. poly(3,4- ethylenedioxythiophene)]. This is fully consistent with the hydrophilicity of the copolymers, which increases with the molecular weight of the PEG chains, and the molecular organization predicted by atomistic molecular dynamics simulations. Graft copolymers tethered to the surface tend to form biphasic structures in solvated environments ( i.e. extended PTh and PEG fragments are perpendicular and parallel to the surface, respectively) while they collapse onto the surface in desolvated environments. Furthermore, the electrochemical activity and the maximum of current density are remarkably higher for samples coated with cells than for uncoated samples, suggesting multiple biotechnological applications in which the transmission with cells is carried out at the electrochemical leve

  • Nanospheres and nanocapsules of amphiphilic copolymers constituted by methoxypolyethylene glycol cyanoacrylate and hexadecyl cyanoacrylate units

     Valente, Ilaria; Del Valle Mendoza, Luis Javier; Casas Becerra, M. Teresa; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge; Marchisio, D.
    Express polymer letters
    Vol. 7, num. 1, p. 2-20
    DOI: 10.3144/expresspolymlett.2013.2
    Date of publication: 2013-01
    Journal article

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  • Examining the formation of specific interactions between poly(3,4-ethylenedioxythiophene) and nucleotide bases

     Zanuy Gomara, David; da Cruz Teixeira Dias, Bruno José; Del Valle Mendoza, Luis Javier; Poater, Jordi; Solà, Miquel; Aleman Llanso, Carlos Enrique
    RSC Advances
    Vol. 3, num. 8, p. 2639-2649
    DOI: 10.1039/c2ra22640e
    Date of publication: 2012-12-17
    Journal article

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  • An electroactive and biologically responsive hybrid conjugate based on chemical similarity

     Fabregat Jove, Georgina; Ballano Ballano, María Gema; Armelin Diggroc, Elaine; Del Valle Mendoza, Luis Javier; Cativiela, Carlos; Aleman Llanso, Carlos Enrique
    Polymer Chemistry
    Vol. 4, num. 5, p. 1412-1424
    DOI: 10.1039/c2py20894f
    Date of publication: 2012-11-20
    Journal article

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    Synthetic amino acids have become very important tools for the design of new materials. In this work, an electroactive polymer–amino acid hybrid material has been synthesized by conjugating poly(3,4-ethylenedioxythiophene) (PEDOT), a well known conducting polymer, with a synthetic amino acid bearing 3,4-ethylenedioxythiophene, which has been explicitly designed and prepared for such a purpose. Nanometric films have been electrochemically generated using a two-step procedure to evaluate the properties and potential applications of the resulting hybrid material. The successful incorporation of the amino acid as end-capping of the PEDOT chains has been proved by FTIR, energy dispersive X-ray and X-ray photoelectron spectroscopies. The fabrication of the hybrid material using an engineered tissue has allowed us to preserve not only morphological and structural characteristics of the conducting polymer but also, and most importantly, to preserve the electrical conductivity, electroactivity, electrochemical stability and specific capacitance. Finally, the behavior of the hybrid material as a cellular matrix has been compared with that of PEDOT using cellular adhesion and proliferation assays. Results obtained in this work represent the success of a new strategy for the preparation of peptide-conducting polymer hybrid materials, which is currently being improved upon by transforming the 3,4-ethylenedioxythiophene-containing amino acid into a cell adhesive peptide

  • Conducting polymer:thermoplastic blends for the fabrication of flexible free-standing ultra-thin membranes: nanomeasures and biomedical applications

     Perez Madrigal, Maria Del Mar; Armelin Diggroc, Elaine; Giannotti, Marina I.; Sanz Carrasco, Fausto; Del Valle Mendoza, Luis Javier; Aleman Llanso, Carlos Enrique
    E-MRS Spring Meeting
    Presentation's date: 2012-05-14
    Presentation of work at congresses

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  • A conducting polymer/protein composite with bactericidal and electroactive properties

     Teixeira Dias, Bruno; Del Valle Mendoza, Luis Javier; Aradilla Zapata, David; Estrany Coda, Francisco; Aleman Llanso, Carlos Enrique
    Macromolecular materials and engineering
    Vol. 297, num. 5, p. 427-436
    DOI: 10.1002/mame.201100172
    Date of publication: 2012-05
    Journal article

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  • Bioactive and electroactive response of flexible polythiophene:Polyester nanomembranes for tissue engineering

     Perez Madrigal, Maria Del Mar; Armelin Diggroc, Elaine; Del Valle Mendoza, Luis Javier; Estrany Coda, Francisco; Aleman Llanso, Carlos Enrique
    Polymer Chemistry
    Vol. 3, num. 4, p. 979-991
    DOI: 10.1039/c2py00584k
    Date of publication: 2012-04
    Journal article

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  • Dextrin- and conducting-polymer-containing biocomposites: Properties and behavior as cellular matrix

     Teixeira Dias, Bruno; Del Valle Mendoza, Luis Javier; Estrany Coda, Francisco; Mano, J.F.; Reis, Rui Luís; Aleman Llanso, Carlos Enrique
    Macromolecular materials and engineering
    Vol. 297, num. 4, p. 359-368
    DOI: 10.1002/mame.201100180
    Date of publication: 2012-04
    Journal article

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    Long time survival of Bartonella bacilliformis in blood stored at 4 ºC. A risk for blood transfusions.  Open access

     Ruiz Blazquez, Joaquim; Silva, Wilmer; Pons, María Jesús; Del Valle Mendoza, Luis Javier; Tinco, Carmen R.; Casabona, Veronica D.; Gomes, Cláudia; Bazan, Jorge; Zabaleta, Víctor; Cornejo Pacheres, Hernán; Champin, Denisse
    Blood transfusion
    Vol. 10, num. 4, p. 563-564
    DOI: 10.2450/2012.0152-11
    Date of publication: 2012-03-29
    Journal article

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  • Levels of quinolones resistance and other antimicrobial in non-pathogenic escherichia coli strains in children from the Periurban area of lima, Peru

     Ruiz Blazquez, Joaquim; Pons, María Jesús; Mosquito, Susan; Ochoa, Theresa J.; Vargas, Martha; Molina, Margarita; Lluque, A.; Gil, A.I.; Ecker, L.; Barletta, F.; Lanata, C.F.; Del Valle Mendoza, Luis Javier
    Revista Peruana de Medicina Experimental y Salud Publica
    Vol. 29, num. 1, p. 82-86
    Date of publication: 2012-03
    Journal article

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  • Biodegradable free-standing nanomembranes of conducting polymer:polyester blends as bioactive platforms for tissue engineering

     Armelin Diggroc, Elaine; Gomes, Alex Linardi; Perez Madrigal, Maria Del Mar; Puiggali Bellalta, Jorge; Franco Garcia, Maria Lourdes; Del Valle Mendoza, Luis Javier; Rodriguez Galan, Rafael Alfonso; Campos, J.S.D.C.; Ferrer Anglada, Nuria; Aleman Llanso, Carlos Enrique
    Journal of materials chemistry B
    Vol. 22, num. 2, p. 585-594
    DOI: 10.1039/c1jm14168f
    Date of publication: 2012-01-14
    Journal article

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  • Electrospun nanofibers of a degradable poly(ester amide). Scaffolds loaded with antimicrobial agents

     Del Valle Mendoza, Luis Javier; Roa Ardilla, Manuel; Diaz Andrade, Angelica Maria; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge; Rodriguez Galan, Rafael Alfonso
    Journal of polymer research
    Vol. 19, num. 2, p. 1-13
    DOI: 10.1007/s10965-011-9792-2
    Date of publication: 2012-01
    Journal article

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  • Biodegradable polyesters reinforced with triclosan loaded polylactide micro/nanofibers: Properties, release and biocompatibility

     Del Valle Mendoza, Luis Javier; Diaz Andrade, Angelica Maria; Royo, M.; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Express polymer letters
    Vol. 6, num. 4, p. 266-282
    DOI: 10.3144/expresspolymlett.2012.30
    Date of publication: 2012
    Journal article

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  • Preparation and release study of ibuprofen-loaded porous matrices of a biodegradable poly(ester amide) derived from L -alanine units

     Del Valle Mendoza, Luis Javier; Roca, Diana; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge; Rodriguez Galan, Rafael Alfonso
    Journal of applied polymer science
    Vol. 122, num. 3, p. 1953-1967
    DOI: 10.1002/app.34017
    Date of publication: 2011-11
    Journal article

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    Scaffolds of a biodegradable poly(ester amide)constituted of L-alanine, sebacic acid, and 1,12-dodecanediol units (abbreviated as PADAS) were prepared by the compression-molding/particulate-leaching method. The influence of the type, size, and percentage of salt on the scaffold porosity and morphology was evaluated. The thermal behavior and crystallinity were also studied for samples obtained under different processing conditions. PADAS scaffolds were not cytotoxic because they showed good cell viability and supported cell growth at a similar ratio to that observed for the biocompatible materials used as a reference. The use of PADAS scaffolds as a drug-delivery system was also evaluated by the employment of ibuprofen, a drug with well known anti-inflammatory effects. Different drug-loading methods were considered, and their influence on the release in a so¨rensen’s medium was evaluated as well as the influence of the scaffold morphology. A sustained release of ibuprofen could be attained without the production of a negative effect on the cell viability. The release kinetics of samples loaded before melt processing was well described by the combined Higuchi/first-order model. This allowed the estimation of the diffusion coefficients, which ranged between 3x10‾14 and 5x10‾13 m2/ s. Samples loaded by immersion in ibuprofen solutions showed a rapid release that could be delayed by the addition of polycaprolactone to the immersion medium (i.e., the release rate decreased from 0.027 to 0.015 h‾1).

  • Electrospinning of polylactide and polycaprolactone mixtures for preparation of materials with tunable drug release properties

     Del Valle Mendoza, Luis Javier; Camps, Roger; Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Journal of polymer research
    Vol. 18, num. 6, p. 1903-1917
    DOI: 10.1007/s10965-011-9597-3
    Date of publication: 2011-11
    Journal article

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