Acrylic acid plasma coated 3D Scaffolds for Cartilage tissue engineering applications

Abstract The current generation of tissue engineered additive manufactured scaffolds for cartilage repair shows high potential for growing adult cartilage tissue. This study proposes two surface modification strategies based on non-thermal plasma technology for the modification of poly(ethylene oxide terephthalate/poly(butylene terephthalate) additive manufactured scaffolds to enhance their cell-material interactions. The first, plasma activation in a helium discharge, introduced non-specific polar functionalities. In the second approach, a carboxylic acid plasma polymer coating, using acrylic acid as precursor, was deposited throughout the scaffolds. Both surface modifications were characterized by significant changes in wettability, linked to the incorporation of new oxygen-containing functional groups. Their capacity for chondrogenesis was studied using ATDC5 chondroblasts as a model cell-line. The results demonstrate that the carboxylic acid-rich plasma coating had a positive effect on the generation of the glucoaminoglycans (GAG) matrix and stimulated the migration of cells throughout the scaffold. He plasma activation stimulated the formation of GAGs but did not stimulate the migration of chondroblasts throughout the scaffolds. Both plasma treatments spurred chondrogenesis by favoring GAG deposition. This leads to the overall conclusion that acrylic acid based plasma coatings exhibit potential as a surface modification technique for cartilage tissue engineering applications

Limiting the valence: advancements and new perspectives on patchy colloids, soft functionalized nanoparticles and biomolecules

Limited bonding valence, usually accompanied by well-defined directional interactions and selective bonding mechanisms, is nowadays considered among the key ingredients to create complex structures with tailored properties: even though isotropically interacting units already guarantee access to a vast range of functional materials, anisotropic interactions can provide extra instructions to steer the assembly of specific architectures. The anisotropy of effective interactions gives rise to a wealth of self-assembled structures both in the realm of suitably synthesized nano- and micro-sized building blocks and in nature, where the isotropy of interactions is often a zero-th order description of the complicated reality. In this review, we span a vast range of systems characterized by limited bonding valence, from patchy colloids of new generation to polymer-based functionalized nanoparticles, DNA-based systems and proteins, and describe how the interaction patterns of the single building blocks can be designed to tailor the properties of the target final structures

Dimensionality changes actin network through lamin A/C and zyxin

Mechanosensing proteins have mainly been investigated in 2D culture platforms, while understanding their regulation in 3D enviroments is critical for tissue engineering. Among mechanosensing proteins, the actin cytoskeleton plays a key role in human mesenchymal stromal cells (hMSCs) activity, but its regulation in 3D tissue engineered scaffolds remains poorly studied. Here, we show that human mesenchymal stromal cells (hMSCs) cultured on 3D electrospun scaffolds made of a stiff material do not form actin stress fibers, contrary to hMSCs on 2D films of the same material. On 3D electrospun and additive manufactured scaffolds, hMSCs also displayed fewer focal adhesions, lower lamin A and C expression and less YAP1 nuclear localization and myosin light chain phosphorylation. Together, this strongly suggests that dimensionality prevents the build-up of cellular tension, even on stiff materials. Knock down of either lamin A and C or zyxin resulted in fewer stress fibers in the cell center. Zyxin knock down reduced lamin A and C expression, but not vice versa, showing that this signal chain starts from the outside of the cell. Lineage commitment was not affected by the lack of these important osteogenic proteins in 3D, as all cells committed to osteogenesis in bi-potential medium. Our study demonstrates that dimensionality changes the actin cytoskeleton through lamin A and C and zyxin, and highlights the difference in the regulation of lineage commitment in 3D enviroments. Together, these results can have important implications for future scaffold design for both stiff- and soft tissue engineering constructs

Alternativas para las dificultades de financiación de las Pymes en España = Alternatives to financial difficulties of Spanish´s SMEs

A través del siguiente trabajo final de grado se pretende estudiar el problema de la financiación de las PYMES en España con el fin de proponer una posible alternativa de financiación en el medio y largo plazo. Las PYMES conforman la mayor parte del tejido productivo/servicios y del empleo en la economía Española. La actual crisis financiera y los principales cambios en materia de la regulación bancaria han llevado a restringir el crédito a las PYMES por parte de las entidades crediticias. Este problema afecta directamente al crecimiento económico y a la creación de empleo en España. Se debe buscar alternativas de financiación para las PYMES que podrían llevar a la necesaria creación de un mercado de renta fija para las PYMES. Para el funcionamiento de dicho mercado tendrán que entrar en juego los diferentes agentes económicos que podrían impulsarlo como son el Estado, las PYMES y las entidades financieras. La propuesta de financiación alternativa de renta fija que se desarrolla en este trabajo es la de un bono con un cupón anual del 5,75%

Spectroscopic binaries in the Solar Twin Planet Search program: from substellar-mass to M dwarf companions

Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do not obey this relation, often by displaying enhanced rotational rates and activity. In the Solar Twin Planet Search program we observed several solar twin binaries, and found a multiplicity fraction of $42\% \pm 6\%$ in the whole sample; moreover, at least three of these binaries (HIP 19911, HIP 67620 and HIP 103983) clearly exhibit the aforementioned anomalies. We investigated the configuration of the binaries in the program, and discovered new companions for HIP 6407, HIP 54582, HIP 62039 and HIP 30037, of which the latter is orbited by a $0.06$ M$_\odot$ brown dwarf in a 1-month long orbit. We report the orbital parameters of the systems with well-sampled orbits and, in addition, the lower limits of parameters for the companions that only display a curvature in their radial velocities. For the linear trend binaries, we report an estimate of the masses of their companions when their observed separation is available, and a minimum mass otherwise. We conclude that solar twin binaries with low-mass stellar companions at moderate orbital periods do not display signs of a distinct rotational evolution when compared to single stars. We confirm that the three peculiar stars are double-lined binaries, and that their companions are polluting their spectra, which explains the observed anomalies.Comment: 13 pages, 7 figures, accepted for publication in MNRA

Auxins, auxin transport inhibitors, and competitors for auxin receptors do not show statistically significant differences in 212 molecular descriptors

[EN] This study compares 212 molecular descriptors of four auxins (indolebutyric acid; indoleacetic acid; 2,4-dichlorophenoxyacetic acid; 1-naphthaleneacetic acid), three auxin transport inhibitors [2-(naphthalen-1-ylcarbamoyl)benzoic acid; 2,3,5-triiodobenzoic acid; 9-hydroxy-9H-fluorene-9-carboxylic acid], and five competitors for auxin receptors [2-(2,4,6-trichlorophenoxy)acetic acid; 2-(4-chlorophenoxy)-2-methylpropanoic acid; 3-phenylpropanoic acid; 3-(2-chlorophenoxy)butanoic acid; 2-amino-3-(5-methyl-1H-indol-3yl) propanoic acid]. The analysed compounds did not show statistically significant differences in any of those descriptors, suggesting that chemical and structural differences, per se, do not determine their functional diversities. We propose that combination with other, yet unknown chemical groups confers the specificity necessary for these molecules to act as auxins, as auxin transport inhibitors or auxin receptor competitors.This research was supported by the Bioplant Centre (University of Ciego de Avila, Cuba) and the Universitat Politecnica de Valencia (Spain).Andújar, I.; Gómez, D.; Pérez, L.; Vicente, O.; Lorenzo, JC. (2019). Auxins, auxin transport inhibitors, and competitors for auxin receptors do not show statistically significant differences in 212 molecular descriptors. Romanian Biotechnological Letters. 24(3):407-411. https://doi.org/10.25083/rbl/24.3/407.411S40741124

The temporal evolution of neutron-capture elements in the Galactic discs

Important insights into the formation and evolution of the Galactic disc(s) are contained in the chemical compositions of stars. We analysed high-resolution and high signal to noise HARPS spectra of 79 solar twin stars in order to obtain precise determinations of their atmospheric parameters, ages ($\sigma$$\sim$0.4 Gyr) and chemical abundances ($\sigma$$<$0.01~dex) of 12 neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy). This valuable dataset allows us to study the [X/Fe]-age relations over a time interval of $\sim$10 Gyr and among stars belonging to the thin and thick discs. These relations show that i) the $s$-process has been the main channel of nucleosynthesis of $n$-capture elements during the evolution of the thin disc; ii) the thick disc is rich in $r$-process elements which suggests that its formation has been rapid and intensive. %; iii) a chemical continuity between the thin and thick discs is evident in the abundances of Ba. In addition, the heavy (Ba, La, Ce) and light (Sr, Y, Zr) $s$-process elements revealed details on the dependence between the yields of AGB stars and the stellar mass or metallicity. Finally, we confirmed that both [Y/Mg] and [Y/Al] ratios can be employed as stellar clocks, allowing ages of solar twin stars to be estimated with an average precision of $\sim$0.5~Gyr

Impact of jets on kilonova photometric and polarimetric emission from binary neutron star mergers

A merger of binary neutron stars creates heavy unstable elements whose radioactive decay produces a thermal emission known as a kilonova. In this paper, we predict the photometric and polarimetric behaviour of this emission by performing 3-D Monte Carlo radiative transfer simulations. In particular, we choose three hydrodynamical models for merger ejecta, two including jets with different luminosities and one without a jet structure, to help decipher the impact of jets on the light curve and polarimetric behaviour. In terms of photometry, we find distinct color evolutions across the three models. Models without a jet show the highest variation in light curves for different viewing angles. In contrast, to previous studies, we find models with a jet to produce fainter kilonovae when viewed from orientations close to the jet axis, compared to a model without a jet. In terms of polarimetry, we predict relatively low levels (<~0.3-0.4%) at all orientations that, however, remain non-negligible until a few days after the merger and longer than previously found. Despite the low levels, we find that the presence of a jet enhances the degree of polarization at wavelengths ranging from 0.25 to 2.5\micron, an effect that is found to increase with the jet luminosity. Thus, future photometric and polarimetric campaigns should observe kilonovae in blue and red filters for a few days after the merger to help constrain the properties of the ejecta (e.g. composition) and jet.Comment: 11 pages, 7 figures, accepted for publication and in pres