Zwitterionic nanofibers of super-glue for transparent and biocompatible multi-purpose coatings

Here we show that macrozwitterions of poly(ethyl 2-cyanoacrylate), commonly called Super Glue, can easily assemble into long and well defined fibers by electrospinning. The resulting fibrous networks are thermally treated on glass in order to create transparent coatings whose superficial morphology recalls the organization of the initial electrospun mats. These textured coatings are characterized by low liquid adhesion and anti-staining performance. Furthermore, the low friction coefficient and excellent scratch resistance make them attractive as solid lubricants. The inherent texture of the coatings positively affects their biocompatibility. In fact, they are able to promote the proliferation and differentiation of myoblast stem cells. Optically-transparent and biocompatible coatings that simultaneously possess characteristics of low water contact angle hysteresis, low friction and mechanical robustness can find application in a wide range of technological sectors, from the construction and automotive industries to electronic and biomedical devices

Porous optically transparent cellulose acetate scaffolds for biomimetic blood-brain barrier in vitro models

In vitro blood-brain barrier (BBB) models represent an efficient platform to conduct high-throughput quantitative investigations on BBB crossing ability of different drugs. Such models provide a closed system where different fundamental variables can be efficaciously tuned and monitored, and issues related to scarce accessibility of animal brains and ethics can be addressed. In this work, we propose the fabrication of cellulose acetate (CA) porous bio-scaffolds by exploiting both vapor-induced phase separation (VIPS) and electrospinning methods. Parameters of fabrication have been tuned in order to obtain porous and transparent scaffolds suitable for optical/confocal microscopy, where endothelial cell monolayers are allowed to growth thus obtaining biomimetic BBB in vitro models. Concerning VIPS-based approach, CA membranes fabricated using 25% H2O + 75% EtOH as non-solvent showed submicrometer-scale porosity and an optical transmittance comparable to that one of commercially available poly(ethylene terephthalate) membranes. CA membranes fabricated via VIPS have been exploited for obtaining multicellular BBB models through the double seeding of endothelial cells and astrocytes on the two surfaces of the membrane. Electrospun CA substrates, instead, were characterized by micrometer-sized pores, and were unsuitable for double seeding approach and long term studies. However, the potential exploitation of the electrospun CA substrates for modeling blood-brain-tumor barrier and studying cell invasiveness has been speculated. The features of the obtained models have been critically compared and discussed for future applications

Proceso de responsabilidad fiscal hoy en Colombia: falencias estructurales para el estado social y democrático de derecho

Las falencias inherentes al diseño constitucional del modelo de recuperación de los recursos públicos en Colombia en cabeza de las entidades de Control Fiscal, en el que hace que éstas funjan como juez y parte, en los procesos administrativos que ejecutan, ratifica su debilidad institucional en el marco del Estado Social y Democrático de Derecho para la eficaz y eficiente recuperación de los dineros públicos, afectando en consecuencia la protección efectiva de los derechos económicos y sociales de la población más pobre y vulnerable. Pues más allá del Control Fiscal, los principios de dignidad humana y la justicia social, así como el logro de la protección de los derechos sociales, la vigilancia y el control sobre la efectividad de una Hacienda Pública que promueva la justicia distributiva, exige una independencia orgánica y funcional de la determinación de la responsabilidad fiscal, pues la garantía de estos principios y valores propios del Estado Social y Democrático de Derecho, corresponde a un tercero (juez), llámese Tribunal de Cuentas o Juez Contencioso Administrativo, quien en perspectiva jurisdiccional posibilite que estos se garanticen plenamente.Abstract. The inherent flaws in the constitutional design of the model for the recovery of public resources in Colombia at the head of the Fiscal Control entities, in which it acts as judge and part, in the administrative processes they execute, ratifies their institutional weakness in the Framework of the Social and Democratic State of Law for the effective and efficient recovery of public monies, affecting in consequence the effective protection of the economic and social rights of the poorest and most vulnerable population. For beyond Fiscal Control, the principles of human dignity and social justice, as well as the achievement of the protection of social rights, vigilance and control over the effectiveness of a Public Treasury that promotes distributive justice, demands independence Organic and functional determination of fiscal responsibility, as the guarantee of these principles and values of the Social and Democratic State of Law, corresponds to a third (judge), called Court of Accounts or Administrative Litigation Judge, who in a jurisdictional perspective That these are fully guaranteed

(Color online) CARS spectra of liquid methanol.

<p>The experimental spectrum, measured with <i>L</i>_<i>pump</i> = 10 cm and <i>L</i>_{<i>Stokes</i>} = 25 cm is shown with circles. The corresponding calculated spectrum is shown as a black solid line. Spectra calculated for <i>L</i>_<i>pump</i> = 0 and <i>L</i>_{<i>Stokes</i>} = 0 (dashed line) and <i>L</i>_<i>pump</i> = 10 cm and <i>L</i>_{<i>Stokes</i>} = 15 cm (dash-dotted line) are also reported for comparison.</p

NMR Relaxation Enhancement of Water Protons by Gd-Doped Boron Nitride Nanotubes

The longitudinal NMR relaxation rate (<i>R</i>₁) of water protons was measured on aqueous suspensions of Gd@BNNTs (i.e., boron nitride nanotubes doped with 0.4% w/w of Gd) coated with glycol-chitosan in the 0.01–30.0 MHz Larmor frequency range, by using a fast field-cycling relaxometer. The dispersion curve of the relaxivity (<i>r</i>₁) relative to Gd, determined exploiting <i>R</i>₁ data from Gd@BNNT and BNNT suspensions, shows a logarithmic dependence on frequency which is characteristic of a relaxation enhancement dominated by an outer sphere mechanism governed by two-dimensional diffusion of water in proximity of Gd³⁺ ions on the BNNT surface. Quantitative information on water diffusion and affinity for the surface was obtained by analyzing the <i>r</i>₁ NMRD curves in terms of a model for two-dimensional diffusion. The effects of the nanotube assembly in water and of the coating hydrophilicity on the interactions between water molecules and Gd³⁺ ions governing the proton relaxation enhancement at the basis of contrast in magnetic resonance imaging (MRI) are discussed

Gold Nanoshell/Polysaccharide Nanofilm for Controlled Laser-Assisted Tissue Thermal Ablation

We report on the fabrication and characterization of a freestanding ultrathin, mucoadhesive gold nanoshell/polysaccharide multilayer nanocomposite (thermonanofilm, TNF), that can be used for controlled photothermal ablation of tissues through irradiation with near-infrared radiation (NIR) laser. The aim of this work is to provide a new strategy to precisely control particle concentration during photothermalization of cancerous lesions, since unpredictable and aspecific biodistributions still remains the central issue of inorganic nanoparticle-assisted photothermal ablation. Gold nanoshell encapsulation in polysaccharide matrix is achieved by drop casting deposition method combined with spin-assisted layer-by-layer (LbL) assembly. Submicrometric thickness of films ensures tissue adhesion. Basic laser-induced heating functionality has been demonstrated by <i>in vitro</i> TNF-mediated thermal ablation of human neuroblastoma cancer cells, evidenced by irreversible damage to cell membranes and nuclei. <i>Ex vivo</i> localized vaporization and carbonization of animal muscular tissue is also demonstrated by applying TNF onto tissue surface. Thermal distribution in the tissue reaches a steady state in a few seconds, with significant increases in temperature (Δ<i>T</i> > 50) occurring across an 1 mm span, ensuring control of local photothermalization and providing more safety and predictability with respect to traditional laser surgery. A steady-state model of tissue thermalization mediated by TNFs is also introduced, predicting the temperature distribution being known the absorbance of TNFs, the laser power, and the tissue thermal conductivity, thus providing useful guidelines in the development of TNFs. Thermonanofilms can find applications for local photothermal treatment of cancerous lesions and wherever high precision and control of heat treatment is required

Nanostructured Brownian Surfaces Prepared through Two-Photon Polymerization: Investigation of Stem Cell Response

Nondeterministic phenomena are at the base of plenty of biological processes that comprise physiological signaling, cellular communications, and biological architectures. Among them, natural surface topographies are often characterized by “chaotic” features that are not trivial to be recreated <i>in vitro</i>. Recently, some methods have been proposed to resemble the hierarchical organization of the extracellular microenvironment, through the chemical preparation of randomly rough and self-affine fractal surfaces. Notwithstanding, this approach does not allow the fractal dimension to be modulated at a desired value, being moreover the self-affinity maintained just for one decade of spatial frequencies. Here, we propose the replication of <i>in silico</i> generated Brownian surfaces through a two-photon polymerization technique. As a result of the direct laser writing of the desired patterns, we were able to obtain highly reproducible self-affine (in a range of two spatial frequency decades) structures characterized by the desired predetermined Hurst exponents. Rat mesenchymal stem cells were moreover cultured on the obtained substrates, highlighting interesting phenomena concerning cell adhesion, cytoskeleton conformation, and actin polymerization, strictly depending on the fractal dimension of the surfaces

Two-Photon Lithography of 3D Nanocomposite Piezoelectric Scaffolds for Cell Stimulation

In this letter, we report on the fabrication, the characterization, and the in vitro testing of structures suitable for cell culturing, prepared through two-photon polymerization of a nanocomposite resist. More in details, commercially available Ormocomp has been doped with piezoelectric barium titanate nanoparticles, and bioinspired 3D structures resembling trabeculae of sponge bone have been fabricated. After an extensive characterization, preliminary in vitro testing demonstrated that both the topographical and the piezoelectric cues of these scaffolds are able to enhance the differentiation process of human SaOS-2 cells

Two-Photon Polymerization of Sub-micrometric Patterned Surfaces: Investigation of Cell-Substrate Interactions and Improved Differentiation of Neuron-like Cells

Direct Laser Writing (DLW) is an innovative tool that allows the photofabrication of high resolution 3D structures, which can be successfully exploited for the study of the physical interactions between cells and substrates. In this work, we focused our attention on the topographical effects of submicrometric patterned surfaces fabricated <i>via</i> DLW on neuronal cell behavior. In particular, we designed, prepared, and characterized substrates based on aligned ridges for the promotion of axonal outgrowth and guidance. We demonstrated that both rat PC12 neuron-like cells and human SH-SY5Y derived neurons differentiate on parallel 2.5 μm spaced submicrometric ridges, being characterized by strongly aligned and significantly longer neurites with respect to those differentiated on flat control substrates, or on more spaced (5 and 10 μm) ridges. Furthermore, we detected an increased molecular differentiation toward neurons of the SH-SY5Y cells when grown on the submicrometric patterned substrates. Finally, we observed that the axons can exert forces able of bending the ridges, and we indirectly estimated the order of magnitude of these forces thanks to scanning probe techniques. Collectively, we showed as submicrometric structures fabricated by DLW can be used as a useful tool for the study of the axon mechanobiology

Piezoelectric Nanoparticle-Assisted Wireless Neuronal Stimulation

Tetragonal barium titanate nanoparticles (BTNPs) have been exploited as nanotransducers owing to their piezoelectric properties, in order to provide indirect electrical stimulation to SH-SY5Y neuron-like cells. Following application of ultrasounds to cells treated with BTNPs, fluorescence imaging of ion dynamics revealed that the synergic stimulation is able to elicit a significant cellular response in terms of calcium and sodium fluxes; moreover, tests with appropriate blockers demonstrated that voltage-gated membrane channels are activated. The hypothesis of piezoelectric stimulation of neuron-like cells was supported by lack of cellular response in the presence of cubic nonpiezoelectric BTNPs, and further corroborated by a simple electroelastic model of a BTNP subjected to ultrasounds, according to which the generated voltage is compatible with the values required for the activation of voltage-sensitive channels