8,740 research outputs found
Development, characterization and sterilisation of Nanocellulose-alginate-(hyaluronic acid)- bioinks and 3D bioprinted scaffolds for tissue engineering
3D-bioprinting is an emerging technology of high potential in tissue engineering (TE), since it shows effective control over scaffold fabrication and cell distribution. Biopolymers such as alginate (Alg), nanofibrillated cellulose (NC) and hyaluronic acid (HA) offer excellent characteristics for use as bioinks due to their excellent biocompatibility and rheological properties. Cell incorporation into the bioink requires sterilisation assurance, and autoclave, β-radiation and γ-radiation are widely used sterilisation techniques in biomedicine; however, their use in 3D-bioprinting for bioinks sterilisation is still in their early stages. In this study, different sterilisation procedures were applied on NC-Alg and NC-Alg-HA bioinks and their effect on several parameters was evaluated. Results demonstrated that NC-Alg and NC-Alg-HA bioinks suffered relevant rheological and physicochemical modifications after sterilisation; yet, it can be concluded that the short cycle autoclave is the best option to sterilise both NC-Alg based cell-free bioinks, and that the incorporation of HA to the NC-Alg bioink improves its characteristics. Additionally, 3D scaffolds were bioprinted and specifically characterized as well as the D1 mesenchymal stromal cells (D1-MSCs) embedded for cell viability analysis. Notably, the addition of HA demonstrates better scaffold properties, together with higher biocompatibility and cell viability in comparison with the NC-Alg scaffolds. Thus, the use of MSCs containing NC-Alg based scaffolds may become a feasible tissue engineering approach for regenerative medicine.Author thanks the Basque Government for granted fellowship to S.
Ruiz-Alonso (PRE_2020_2_0143). This study was financially supported
by the Basque Country Government (IT907-16), the Ministerio de
Economía, Industria y Competitividad (FEDER funds, project RTC-2016-
5451-1), Fundación Mutua Madrileña (project FMM-AP17196-2019),
the Instituto de Salud Carlos III, ERDF funds (DTS19/00145) and by
the Consejería de Economía, Conocimiento, Empresas y Universidad,
Junta de Andalucía (project no. PY18-2470 and SOMM17/6109/UGR,
FEDER Funds). Authors also wish to thank the intellectual and technical
assistance from the ICTS “NANBIOSIS”, more specifically by the Drug
Formulation Unit (U10) of the CIBER in Bioengineering, Biomaterials &
Nanomedicine (CIBER-BBN) at the University of Basque Country (UPV/
EHU
Pyridinethiolate titanocene metalloligands and their self-assembly reactions to yield early–late metallamacrocycles
New titanocene pyridinethiolate compounds [(RCp)2Ti(4-Spy)2] (R = H (1), Me (2); Cp = cyclopentadienyl; 4-Spy = pyridine-4-thiolate) and [Cp2Ti(2-Spy)2] (3; 2-Spy = pyridine-2-thiolate) have been prepared by reaction of the corresponding Li(Spy) salt with the appropriate compound [(RCp)2TiCl2]. Compounds 1 and 2 have been used as metalloligands in self-assembly reactions with the acceptor late-transition-metal compounds [M(H2O)2(dppp)](OTf)2 (M = Pd (a) Pt (b); dppp = 1,3-bis(diphenylphosphino)propane), and the series of early–late tetranuclear metallamacrocycles [{(RCp)2Ti(4-Spy)2}{M(dppp)}]2(OTf)4 (R = H, M = Pd (12a2); R = H, M = Pt (12b2); R = Me, M = Pd (22a2); R = Me, M = Pt (22b2)) arising from the anti isomer of the titanocene metalloligands have been obtained. Only ligand transfer reactions from Ti to either Pd or Pt atoms have been observed when the pyridine-2-thiolate derivative 3 has been assayed in self-assembly processes. The obtained species have been characterized by NMR spectroscopy and ESI(+) mass spectrometry. The supramolecular assemblies have shown to be nonrigid in solution, and their fluxional behavior has been studied by VT 1H NMR spectroscopy. A DFT study including ab initio molecular dynamics in order to elucidate the structures and the relative stability of the isomers has been performed.Financial support for this work was provided by the Ministerio de Economía y Competitividad (MINECO/FEDER) of Spain (CTQ2013-42532-P and CTQ2012-31335), Diputación General de Aragón (Group E07) and Fondo Social Europeo. E.R. thanks Generalitat de Catalunya for an ICREA Academia fellowship.Peer reviewe
Metal-Controlled Magnetoresistance at Room Temperature in Single-Molecule Devices
The appropriate choice of the transition metal complex and metal surface electronic structure opens the possibility to control the spin of the charge carriers through the resulting hybrid molecule/metal spinterface in a single molecule electrical contact at room temperature. The single molecule conductance of a Au/molecule/Ni junction can be switched by flipping the magnetization direction of the ferromagnetic electrode. The requirements of the molecule include not just the presence of unpaired electrons: the electronic configuration of the metal center has to provide occupied or empty orbitals that strongly interact with the junction metal electrodes and that are close in energy to their Fermi levels for one of the electronic spins only. The key ingredient for the metal surface is to provide an efficient spin texture induced by the spin orbit coupling in the topological surface states that results in an efficient spin-dependent interaction with the orbitals of the molecule. The strong magnetoresistance effect found in this kind of single-molecule wire opens a new approach for the design of room-temperature nanoscale devices based on spin-polarized currents controlled at molecular level
Pyridinethiolate titanocene metalloligands and their self-assembly reactions to yield early-late metallamacrocycles
New titanocene pyridinethiolate compounds [(RCp)(2)Ti(4-Spy)(2)] (R = H (1), Me (2); Cp = cyclo-pentadienyl; 4-Spy = pyridine-4-thiolate) and [Cp2Ti(2-Spy)(2)] (3; 2-Spy = pyridine-2-thiolate) have been prepared by reaction of the corresponding Li(Spy) salt with the appropriate compound [(RCp)(2)TiCl2]. Compounds 1 and 2 have been used as metalloligands in self-assembly reactions with the acceptor late-transition-metal compounds [M(H2O)(2)(dppp)]-(OTf)(2) (M = Pd (a) Pt (b); dppp = 1,3-bis-(diphenylphosphino)propane), and the series of early-late tetranuclear metallamacrocycles [{(RCp)(2)Ti(4-Spy)(2)}{M-(dppp)}](2)(OTf)(4) (R = H, M = Pd (1(2)a(2)); R = H, M = Pt (1(2)b(2)); R = Me, M = Pd (2(2)a(2)); R = Me, M = Pt (2(2)b(2))) arising from the anti isomer of the titanocene metalloligands have been obtained. Only ligand transfer reactions from Ti to either Pd or Pt atoms have been observed when the pyridine-2-thiolate derivative 3 has been assayed in self-assembly processes. The obtained species have been characterized by NMR spectroscopy and ESI(+) mass spectrometry. The supramolecular assemblies have shown to be nonrigid in solution, and their fluxional behavior has been studied by VT H-1 NMR spectroscopy. A DFT study including ab initio molecular dynamics in order to elucidate the structures and the relative stability of the isomers has been performed
New Biochemical Insights into the Mechanisms of Pulmonary Arterial Hypertension in Humans
Diagnosis of pulmonary arterial hypertension (PAH) is difficult due to the lack of specific clinical symptoms and biomarkers, especially at early stages. We compared plasma metabolic fingerprints of PAH patients (n = 20) with matched healthy volunteers (n = 20) using, for the first time, untargeted multiplatform metabolomics approach consisting of high-performance liquid and gas chromatography coupled with mass spectrometry. Multivariate statistical analyses were performed to select metabolites that contribute most to groups' classification (21 from liquid in both ionization modes and 9 from gas chromatography-mass spectrometry). We found metabolites related to energy imbalance, such as glycolysis-derived metabolites, as well as metabolites involved in fatty acid, lipid and amino acid metabolism. We observed statistically significant changes in threitol and aminomalonic acid in PAH patients, which could provide new biochemical insights into the pathogenesis of the disease. The results were externally validated on independent case and control cohorts, confirming up to 16 metabolites as statistically significant in the validation study. Multiplatform metabolomics, followed by multivariate chemometric data analysis has a huge potential for explaining pathogenesis of PAH and for searching potential and new more specific and less invasive markers of the disease.This research was supported by the Polish National Science Center (2014/13/N/NZ7/04231), the Spanish Ministry of Economy and Competitiveness (MINECO) (SAF2014-58920R), by the Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III and co-funding by Fondo Europeo de Desarrollo Regional (FEDER) (PI14-01427), and by the quality-promoting subsidy from the Ministry of Science and Higher Education of Poland, Leading National Research Centre (KNOW programme 2012-2017). The CNIC is supported by the Spanish Ministry of Economy and Competitiveness and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S
The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey
Context. Thanks to recent and ongoing large scale surveys, hundreds of brown
dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf
Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam
camera on the Canada-France-Hawaii Telescope telescope. Aims. Our objectives
are to find ultracool brown dwarfs and to constrain the field brown-dwarf
luminosity function and the mass function from a large and homogeneous sample
of L and T dwarfs. Methods. We identify candidates in CFHT/MegaCam i' and z'
images and follow them up with pointed near infrared (NIR) imaging on several
telescopes. Halfway through our survey we found ~50 T dwarfs and ~170 L or
ultra cool M dwarfs drawn from a larger sample of 1400 candidates with typical
ultracool dwarfs i' - z' colours, found in 780 square degrees. Results. We have
currently completed the NIR follow-up on a large part of the survey for all
candidates from mid-L dwarfs down to the latest T dwarfs known with utracool
dwarfs' colours. This allows us to draw on a complete and well defined sample
of 102 ultracool dwarfs to investigate the luminosity function and space
density of field dwarfs. Conclusions. We found the density of late L5 to T0
dwarfs to be 2.0pm0.8 x 10-3 objects pc-3, the density of T0.5 to T5.5 dwarfs
to be 1.4pm0.3 x 10-3 objects pc-3, and the density of T6 to T8 dwarfs to be
5.3pm3.1 x 10-3 objects pc-3 . We found that these results agree better with a
flat substellar mass function. Three latest dwarfs at the boundary between T
and Y dwarfs give the high density 8.3p9.0m5.1 x 10-3 objects pc-3. Although
the uncertainties are very large this suggests that many brown dwarfs should be
found in this late spectral type range, as expected from the cooling of brown
dwarfs, whatever their mass, down to very low temperature.Comment: Accepted for publication in A&
Recent advances on dendrogeomorphological research applied to flood hazard analysis in Spain.
Estudios dendroecológicos para el análisis de regímentes torrenciales y avenida
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