Suchergebnisse

Tissue engineering and regenerative medicine are increasingly taking advantage of active materials, allowing to provide specific clues to the cells. In particular, the use of electroactive polymers that deliver an electrical signal to the cells upon mechanical solicitation, open new scientific and technological opportunities, as they in fact mimic signals and effects that occur in living tissues, allowing the development of suitable microenvironments for tissue regeneration. Thus, a novel overall strategy for bone and muscle tissue engineering was developed based on the fact that these cells type are subjected to mechano-electrical stimuli in their in vivo microenvironment and that piezo- and magnetoelectric polymers, used as scaffolds, are suitable for delivering those cues. The processing and functional characterizations of piezoelectric and magnetoelectric polymers based on poly(vinylindene fluoride) and poly-L-lactic acid in a variety of shapes, from microspheres to electrospun mats and three dimensional scaffolds, are shown as well as their performance in the development of novel bone and muscle tissue engineering. ; The authors thank the Portuguese Fundação para a Ciência e Tecnologia (FCT) for financial support under Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014, including FEDER funds, UE. The authors also thank the FCT for financial support under grants SFRH/BPD/90870/2012 (CR), SFRH/BPD/121526/2016 (DMC), SFRH/BD/111478/2015 (SR) and SFRH/BPD/121464/2016 (MMF). Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry Department under the ELKARTEK Program is also acknowledged. ...

Sustainable materials are increasingly needed in lithium ion batteries in order to reduce their environmental impact and improve their recyclability. This work reports on the production of separators using poly (L-lactic acid) (PLLA) for lithium ion battery applications. PLLA separators were obtained by solvent casting technique, by varying polymer concentration in solution between 8 wt.% and 12 wt.% in order to evaluate their morphology, thermal, electrical and electrochemical properties. It is verified that morphology and porosity can be tuned by varying polymer concentration and that the separators are thermally stable up to 250 ºC. The best ionic conductivity of 1.6 mS/cm was obtained for the PLLA separator prepared from 10 wt.% polymer concentration in solution, due to the synergistic effect of the morphology and electrolyte uptake. For this membrane, a high discharge capacity value of 93 mAh.g-1 was obtained at the rate of 1C. In this work, it is demonstrated that PLLA is a good candidate for the development of separator membranes, in order to produce greener and environmentally friendly batteries in a circular economy context. ; Work supported by the Portuguese Foundation for Science and Technology (FCT) undes strategic funding UID/FIS/04650/2020 and UID/QUI/0686/2020, project PTDC/FISMAC/28157/2017, and Grants SFRH/BD/140842/2018 (J.C.B.), SFRH/BPD/121526/2016 (D.M.C), CEECIND/00833/2017 (R.G.) and SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged. Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, EGEF and ESF) is gratefully ...

Electrospun poly(vinylidene fluoride) (PVDF) fiber membranes doped with different ionic liquids (ILs) and sharing the same anion were produced and their potential as separator membranes for battery applications was evaluated. Different types of ILs containing the same anion, bis(trifluoromethylsulfonyl)im ide [TFSI] , were used with IL concentrations ranging between 0 and 15 wt% The morphology, microstructure, thermal and electrical properties (ionic conductivity and electrochemical window) of the membranes were evaluated. The presence of ILs in the PVDF polymer matrix influences the fiber diameter and the content of the polar 13 phase within the polymer, as well as the degree of crystallinity. The thermal stability of the membranes decreases with the incorporation of IL. Impedance spectroscopy tests show a maximum ionic conductivity of 2.8 mS.cm(-1) for 15% of 1-ethyl-3-methylimidazolium bis(tri fluoromethylsulfonyl)imide ([Emim][TFSI]) at room temperature. The electrochemical stability of the samples ranges from 0.0 to 6.0 V. When evaluated as battery separator membranes in C-LiFePO4 halfcells, a maximum discharge capacity of 119 mAh.g(-1) at C-rate was obtained for the PVDF membrane with 15% [Emim][TFSI], with a coulombic efficiency close to 100%. The results demonstrate that the produced electrospun membranes are suitable for applications as separators for lithium ion batteries (LIBs). ; Work supported by the Portuguese Foundation for Science and Technology (FCT): projects UID/FIS/04650/2019, UID/QUI/0686/2019, UID/CTM/50025/2019, UID/QUI/50006/2019, PTDC/FIS-MAC/28157/2017, and Grants SFRH/BD/140842/2018 (J.C.B.), SFRH/BPD/121526/2016 (D.M.C), CEECIND/00833/2017 (R.G.) and SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-1060 99RB-C43/AEI/10.13039/501100011033 and from the Basque Government Industry and Education Departments under the ELKARTEK and HAZITEK programs is also ...

"Available online 11 May 2016" ; Biodegradable poly(L-lactic acid) (PLLA) and PLLA/CoFe2O4 magnetic microspheres with average sizes ranging between 0.16 -3.9 m and 0.8-2.2 m, respectively, were obtained by an oil-in-water emulsion method using poly(vinyl alcohol) (PVA) solution as the emulsifier agent. The separation of the microspheres in different size ranges was then performed by centrifugation and the colloidal stability assessed at different pH values. Neat PLLA spheres are more stable in alkaline environments when compared to magnetic microspheres, both types being stable for pHs higher than 4, resulting in a colloidal suspension. On the other hand, in acidic environments the microspheres tend to form aggregates. The neat PLLA microspheres show a degree of crystallinity of 40% whereas the composite ones are nearly amorphous (17%). Finally, the biocompatibility was assessed by cell viability studies with MC3T3-E1 pre-osteoblast cells. ; This work is funded by FCT – Fundação para a Ciência e a Tecnologia, grants SFRH/BD/82411/2011 (DMC), SFRH/ BPD/90870/2012 (CR), SFRH/BD/98616/2013 (PMM) and SFRH/ BPD/97739/2013 (PM), respectively. The authors thank support from the COST Action MP1206 ''Electrospun Nano-fibres for bio inspired composite materials and innovative industrial applications" and from the Basque Government Industry Department under the ELKARTEK Program. SLM thanks the Diputación Foral de Bizkaia for financial support under the Bizkaia Talent Programme; European Union's Seventh Framework Programme; Marie Curie Actions–People; Grant agreement no. ...

Photocurable thermochromic and humidity responsive materials based on polyurethane acrylated (PUA) and bis(1-butyl-3-methylimidazolium) tetrachloronickelate ([Bmim]2[NiCl4]) ionic liquid (IL) have been prepared with varying IL content up to 40 wt% within the polymer matrix. The influence of IL content on the photopolymerization process, morphology, Young modulus and electrical conductivity of the materials was evaluated. All materials present a total polymer conversion of at least 88%. The presence of the IL influences the morphology of PUA, being observed a porous network structure upon IL incorporation into the PUA matrix. All samples show a Tg around room temperature, which is independent of the IL content and a Young modulus that decreases with the IL content. All composites exhibit humidity dependent thermochromism from colourless to blue. Further, the influence of the relative humidity in the colour change was accessed for the sample containing 20 wt% [Bmim]2[NiCl4], being observed that the colour variation is thermally activated and humidity governed, being 55% the minimum value of the relative humidity for colour change to occur. ; FCT (Fundação para a Ciência e Tecnologia) for financial support under the framework of Strategic Funding grants UID/FIS/04650/2020, UID/EEA/04436/2020 and UID/QUI/0686/2020 and project no. PTDC/FIS-MAC/28157/2017. The authors thank funding by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43/AEI/10.13039/501100011033 and under the Operational Programme "Competitiveness and Internationalization" - Research and Development (R&D) and Innovation to SMEs – R&D Individuals Projects, grant agreement number 038397. M. S. also acknowledge the National Research grant "Juan de la Cierva" FJCI-2017-31761. Financial support from the Basque Government Industry and Education Departments under the ELKARTEK, HAZITEK and PIBA programs is also acknowledged. LCF and DCM also thank the grant ...

The aim of this work was to determine the influence of the biomaterial environment on human mesenchymal stem cell (hMSC) fate when cultured in supports with varying topography. Poly(vinylidene fluoride) (PVDF) culture supports were prepared with structures ranging between 2D and 3D, based on PVDF films on which PVDF microspheres were deposited with varying surface density. Maintenance of multipotentiality when cultured in expansion medium was studied by flow cytometry monitoring the expression of characteristic hMSCs markers, and revealed that cells were losing their characteristic surface markers on these supports. Cell morphology was assessed by scanning electron microscopy (SEM). Alkaline phosphatase activity was also assessed after seven days of culture on expansion medium. On the other hand, osteoblastic differentiation was monitored while culturing in osteogenic medium after cells reached confluence. Osteocalcin immunocytochemistry and alizarin red assays were performed. We show that flow cytometry is a suitable technique for the study of the differentiation of hMSC seeded onto biomaterials, giving a quantitative reliable analysis of hMSC-associated markers. We also show that electrosprayed piezoelectric poly(vinylidene fluoride) is a suitable support for tissue engineering purposes, as hMSCs can proliferate, be viable and undergo osteogenic differentiation when chemically stimulated. ; The authors thank the Portuguese Foundation for Science and Technology (FCT) for financial support under project PTDC/EEI-SII/5582/2014, Strategic Funding UID/FIS/04650/2013 and grants SFRH/BPD/90870/2012 (C.R.) and SFRH/BPD/121526/2016 (D.M.C). The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry Department under the ELKARTEK program. JLGR, LC, RSS and AS acknowledge funding by the Conselleria de Educación, Investigación, Cultura y Deporte of the Generalitat Valenciana through ...

[EN] The aim of this work was to determine the influence of the biomaterial environment on human mesenchymal stem cell (hMSC) fate when cultured in supports with varying topography. Poly(vinylidene fluoride) (PVDF) culture supports were prepared with structures ranging between 2D and 3D, based on PVDF films on which PVDF microspheres were deposited with varying surface density. Maintenance of multipotentiality when cultured in expansion medium was studied by flow cytometry monitoring the expression of characteristic hMSCs markers, and revealed that cells were losing their characteristic surface markers on these supports. Cell morphology was assessed by scanning electron microscopy (SEM). Alkaline phosphatase activity was also assessed after seven days of culture on expansion medium. On the other hand, osteoblastic differentiation was monitored while culturing in osteogenic medium after cells reached confluence. Osteocalcin immunocytochemistry and alizarin red assays were performed. We show that flow cytometry is a suitable technique for the study of the differentiation of hMSC seeded onto biomaterials, giving a quantitative reliable analysis of hMSC-associated markers. We also show that electrosprayed piezoelectric poly(vinylidene fluoride) is a suitable support for tissue engineering purposes, as hMSCs can proliferate, be viable and undergo osteogenic differentiation when chemically stimulated. ; The authors thank the Portuguese Foundation for Science and Technology (FCT) for financial support under project PTDC/EEI-SII/5582/2014, Strategic Funding UID/FIS/04650/2013 and grants SFRH/BPD/90870/2012 (C.R.) and SFRH/BPD/121526/2016 (D.M.C). The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry Department under the ELKARTEK program. JLGR, LC, RSS and AS acknowledge funding by the Conselleria de Educacion, Investigacion, Cultura y Deporte of the Generalitat Valenciana through ...