Human mesenchymal stem cells growth and osteogenic differentiation on piezoelectric poly(vinylidene fluoride) microsphere substrates

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 PROMETEO/2016/063 project. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development. This work was partially financed with FEDER funds (CIBERONC (CB16/12/00284)). The authors acknowledge the assistance and advice of Electron Microscopy Service of the UPVinfo:eu-repo/semantics/publishedVersio

Crystallization kinetics of poly(ethylene oxide) confined in semicrystalline poly(vinylidene) fluoride

Polymer blends based on poly(vinylidene fluoride) (PVDF) and poly(ethylene oxide) (PEO) have been prepared to analyze the crystallization kinetics of poly(ethylene oxide) confined in semicrystalline PVDF with different ratios of both polymers. Both blend components were dissolved in a common solvent, dimethyl formamide. Blend films were obtained by casting from the solution at 70 degrees C. Thus, PVDF crystals are formed by crystallization from the solution while PEO (which is in the liquid state during the whole process) is confined between PVDF crystallites. The kinetics of crystallization of the confined PEO phase was studied by isothermal and nonisothermal experiments. Fitting of Avrami model to the experimental DSC traces allows a quantitative comparison of the influence of the PVDF/PEO ratio in the blend on the crystallization behavior. The effect of melting and further recrystallization of the PVDF matrix on PEO confinement is also studied.The authors thank the assistance and advice of Electron Microscopy Service of the UPV. This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-1 and 3-R (including the FEDER financial support); CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions, and by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund; FEDER funds through the COMPETE 2020 Programme and National Funds through FCT-Portuguese Foundation for Science and Technology under Strategic Funding UID/FIS/04650/2013; the FCT grant SFRH/BPD/112547/2015 (to C.M.C.); support from the Basque Government Industry Department under the ELKARTEK Program; the doctoral grant from the Programa de Ayudade Investigacion y Desarrollo (PAID) of the Universitat Politecnicade Valencia (to M.N.T.-M.).info:eu-repo/semantics/publishedVersio

Composition dependent physical properties of poly[(vinylidene fluoride)-co-trifluoroethylene] - poly(ethylene oxide) blends

Polymer blends based on poly(vinylidene fluoride – co – trifluoroethylene) copolymers, P(VDF-TrFE), and poly(ethylene oxide), PEO, with varying compositions have been prepared by solvent casting. In this way, P(VDF-TrFE) crystallizes from the solution while solvent evaporates, while PEO crystallizes from the melt during cooling to room temperature. The surface morphology of the polymer blends indicates the transition from the fibrillar microstructure typical of PVDF-TrFE to the spherulite structure characteristic of PEO. The vibration modes characteristics of P(VDF-TrFE) are not influenced by the presence of PEO in the polymer blend. Confinement of PEO in the P(VDF-TrFE) phase change the conformation of PEO from trans to helix, increasing this transformation for increasing P(VDF-TrFE) content in the polymer blends. Sequential crystallization of the two polymers produce separated amorphous phases whose independent cooperative conformational motions are revealed by two main dynamic-mechanical relaxations. No chemical interaction seems to exist between the polymers within the blend.Abstract: Polymer blends based on poly(vinylidene fluoride – co – trifluoroethylene) copolymers, P(VDF-TrFE), and poly(ethylene oxide), PEO, with varying compositions have been prepared by solvent casting. In this way, P(VDF-TrFE) crystallizes from the solution while solvent evaporates, while PEO crystallizes from the melt during cooling to room temperature. The surface morphology of the polymer blends indicates the transition from the fibrillar microstructure typical of PVDF-TrFE to the spherulite structure characteristic of PEO. The vibration modes characteristics of P(VDF-TrFE) are not influenced by the presence of PEO in the polymer blend. Confinement of PEO in the P(VDF-TrFE) phase change the conformation of PEO from trans to helix, increasing this transformation for increasing P(VDF-TrFE) content in the polymer blends. Sequential crystallization of the two polymers produce separated amorphous phases whose independent cooperative conformational motions are revealed by two main dynamic-mechanical relaxations. No chemical interaction seems to exist between the polymers within the blend