Poly(vinylidene) fluoride membranes coated by heparin/collagen layer-by-layer, smart biomimetic approaches for mesenchymal stem cell culture

[EN] The use of piezoelectric materials in tissue engineering has grown considerably since inherent bone piezoelectricity was discovered. Combinations of piezoelectric polymers with magnetostrictive nanoparticles (MNP) can be used to magnetoelectrically stimulate cells by applying an external magnetic field which deforms the magnetostrictive nanoparticles in the polymer matrix, deforming the polymer itself, which varies the surface charge due to the piezoelectric effect. Poly(vinylidene) fluoride (PVDF) is the piezoelectric polymer with the largest piezoelectric coefficients, being a perfect candidate for osteogenic differentiation. As a first approach, in this paper, we propose PVDF membranes containing magnetostrictive nanoparticles and a biomimetic heparin/ collagen layer-by-layer (LbL) coating for mesenchymal stem cell culture. PVDF membranes 20% (w/v) with and without cobalt ferrite oxide (PVDF-CFO) 10% (w/w) were produced by non-solvent induced phase separation (NIPS). These membranes were found to be asymmetric, with a smooth surface, crystallinity ranging from 65% to 61%, and an electroactive beta-phase content of 51.8% and 55.6% for PVDF and PVDF-CFO, respectively. Amine groups were grafted onto the membrane surface by an alkali treatment, confirmed by ninhydrin test and X-ray photoelectron spectroscopy (XPS), providing positive charges for the assembly of heparin/collagen layers by the LbL technique. Five layers of each polyelectrolyte were deposited, ending with collagen. Human mesenchymal stem cells (hMSC) were used to test cell response in a short-term culture (1, 3 and 7 days). Nucleus cell counting showed that LbL favored cell proliferation in PVDF-CFO over non-coated membranes.This work has been funded by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the PID2019-106099RB-C41/AEI/10.13039/501100011033 and PID2019-106099RB-C43/AEI/10.13039/501100011033 projects and the Associate Laboratory for Green Chemistry-LAQV financed by national funds from FCT/MCTES (UIDB/50006/2020). Maria GuillotFerriols acknowledges the Spanish Government funding of her doctoral thesis through a BES-2017-080398 FPI Grant. The CIBER-BBN (CB06/01/1026) initiative is funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. D.M.C is also grateful to the FCT-Fundacao para a Ciencia e Tecnologia for grant SFRH/BPD/121526/2016. 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Gold nanoparticles deposited on surface modified carbon materials as reusable catalysts for hydrocarboxylation of cyclohexane

Gold nanoparticles were deposited on different carbon materials and used as catalysts for the alkane hydrocarboxylation reaction. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid was carried out in the presence of CO and water, peroxodisulfate, in water/acetonitrile medium, at ca. 50 degrees C, with gold nanoparticles deposited by a colloidal method on carbon nanotubes and activated carbon with three different surface chemistries: in their original forms (CNT or AC, respectively), oxidized with HNO3 (ox) or oxidized with HNO3 and subsequently treated with NaOH (-ox-Na). Au/CNT-ox-Na was the best catalyst, yielding cyclohexanecarboxylic acid up to 88.2% yield, with excellent recyclability (97.5% of the initial activity was maintained after five consecutive catalytic cycles).info:eu-repo/semantics/publishedVersio

Facet-dependent reactivity of Fe2O3/CeO2 nanocomposites: Effect of ceria morphology on CO oxidation

Ceria has been widely studied either as catalyst itself or support of various active phases in many catalytic reactions, due to its unique redox and surface properties in conjunction to its lower cost, compared to noble metal-based catalytic systems. The rational design of catalytic materials, through appropriate tailoring of the particles’ shape and size, in order to acquire highly efficient nanocatalysts, is of major significance. Iron is considered to be one of the cheapest transition metals while its interaction with ceria support and their shape-dependent catalytic activity has not been fully investigated. In this work, we report on ceria nanostructures morphological effects (cubes, polyhedra, rods) on the textural, structural, surface, redox properties and, consequently, on the CO oxidation performance of the iron-ceria mixed oxides (Fe2O3/CeO2). A full characterization study involving N2 adsorption at -196 °C, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) was performed. The results clearly revealed the key role of support morphology on the physicochemical properties and the catalytic behavior of the iron-ceria binary system, with the rod-shaped sample exhibiting the highest catalytic performance, both in terms of conversion and specific activity, due to its improved reducibility and oxygen mobility, along with its abundance in Fe2+ species. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Oxido-and dioxido-vanadium(V) complexes supported on carbon materials: Reusable catalysts for the oxidation of cyclohexane

Oxidovanadium(V) and dioxidovanadium(V) compounds, [VO(OEt)L] (1) and [Et3NH][VO2L] (2), were synthesized using an aroylhydrazone Schiff base (5-bromo-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H2L). They were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), (1H and51V) nuclear magnetic resonance (NMR), electrospray ioniza-tion mass spectrometry (ESI-MS) and single crystal X-ray diffraction analyses. Both complexes were immobilized on functionalized carbon nanotubes and activated carbon. The catalytic performances of 1 and 2, homogenous and anchored on the supports, were evaluated for the first time towards the MW-assisted peroxidative oxidation (with tert-butylhydroperoxide, TBHP) of cyclohexane under heterogeneous conditions. The immobilization of 1 and 2 on functionalized carbon materials improved the efficiency of catalytic oxidation and allowed the catalyst recyclability with a well-preserved catalytic activity. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Synthesis of a novel series of Cu(I) complexes bearing alkylated 1,3,5-triaza-7-phosphaadamantane as homogeneous and carbon-supported catalysts for the synthesis of 1-and 2-substituted-1,2,3-triazoles

The N-alkylation of 1,3,5-triaza-7-phosphaadamantane (PTA) with ortho-, meta-and para-substituted nitrobenzyl bromide under mild conditions afforded three hydrophilic PTA ammonium salts, which were used to obtain a new set of seven water-soluble copper(I) complexes. The new compounds were fully characterized and their catalytic activity was investigated for the low power microwave assisted one-pot azide–alkyne cycloaddition reaction in homogeneous aqueous medium to obtain disubstituted 1,2,3-triazoles. The most active catalysts were immobilized on activated carbon (AC), multi-walled carbon nanotubes (CNT), as well as surface functionalized AC and CNT, with the most efficient support being the CNT treated with nitric acid and NaOH. In the presence of the immobilized catalyst, several 1,4-disubstituted-1,2,3-triazoles were obtained from the reaction of terminal alkynes, organic halides and sodium azide in moderate yields up to 80%. Furthermore, the catalyzed reaction of terminal alkynes, formaldehyde and sodium azide afforded 2-hydroxymethyl-2H-1,2,3-triazoles in high yields up to 99%. The immobilized catalyst can be recovered and recycled through simple workup steps and reused up to five consecutive cycles without a marked loss in activity. The described catalytic systems proceed with a broad substrate scope, under microwave irradiation in aqueous medium and according to “click rules”. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

ΕΠΙΔΡΑΣΗ ΤΗΣ ΜΟΡΦΟΛΟΓΙΑΣ ΤΟΥ ΦΟΡΕΑ (ΝΑΝΟ-CeO2) ΣΤΑ ΦΥΣΙΚΟΧΗΜΙΚΑ ΚΑΙ ΚΑΤΑΛΥΤΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΥΠΟΣΤΗΡΙΓΜΕΝΩΝ ΜΕΤΑΛΛΩΝ ΜΕΤΑΠΤΩΣΗΣ MΟx/CeO2 (M: Ni, Co, Fe)

Το οξείδιο του δημητρίου ή δημητρία (CeO2) έχει προσελκύσει ιδιαίτερο ερευνητικό ενδιαφέρον κι έχει χρησιμοποιηθεί σε πλήθος καταλυτικών αντιδράσεων λόγω των μοναδικών οξειδοαναγωγικών του ιδιοτήτων. Ειδικότερα, η σύνθεση υλικών δημητρίας σε επίπεδο νανο-κλίμακας καθορισμένης αρχιτεκτονικής και μορφολογίας μπορεί να οδηγήσει σε σημαντικές μεταβολές στις δομικές, επιφανειακές και οξειδοαναγωγικές ιδιότητες. Επιπλέον, ιδιαίτερα σημαντική κρίνεται η ανάπτυξη μικτών οξειδίων βασισμένων στο CeO2, τα οποία θα χαρακτηρίζονται από υψηλή δραστικότητα και χαμηλό κόστος και τα οποία θα είναι απαλλαγμένα από ευγενή μέταλλα. Στην παρούσα εργασία μελετήθηκε η επίδραση της νανο-δομής του φορέα CeO2 στα φυσικοχημικά χαρακτηριστικά και την καταλυτική συμπεριφορά υποστηριγμένων μετάλλων μετάπτωσης, ήτοι MOx/CeO2 (M: Ni, Co, Fe). Ως φορέας χρησιμοποιήθηκε σε όλες τις περιπτώσεις νανο-CeO2 διαφορετικής μορφολογίας, η οποία παρασκευάστηκε με την υδροθερμική μέθοδο. Ο χαρακτηρισμός των υλικών πραγματοποιήθηκε μέσω των τεχνικών BET, XRD, TEM, TPR, ενώ η καταλυτική τους συμπεριφορά μελετήθηκε κατά την αντίδραση οξείδωσης του CO