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

Polymeric foams with functional nanocomposite cells

A novel strategy for the fabrication of elastomeric poly(dimethylsiloxane) (PDMS) foams with interconnected nanocomposite cells of controlled size is presented. Beads of the natural hydrogel calcium alginate are used as templates for the fabrication of the foams and as initiators for the functionalization of their cells with gold nanoparticles. The hydrogel beads are easily fabricated via external gelation using a fluidic system that permits the control of their size. As a subsequent step, they are assembled in containers where PDMS pre-polymer is poured. As the elastomer cures, the beads shrink releasing the liquid they contain and forming pores in the polymer matrix. By introducing gold precursor solution in the beads, it is possible to develop foams with gold nanoparticles immobilized on the surface of their cells. As the gold ion solution is released by the beads, it chemically interacts with the PDMS, forming nanoparticles locally on the surface of the cavities of the foams. The same procedure can be expanded to various substances resulting in functional foams with localized properties, with applications envisaged in the biomedical field

Localized synthesis of gold nanoparticles in anisotropic alginate structures

We present a method to create alginate nanocomposite objects having two regions with distinct chemical composition by spatially confining the synthesis of gold nanoparticles (Au NPs) in the polysaccharide matrix. Controlling the floating of sodium alginate drops on calcium chloride solution containing specific concentrations of gold ions, we demonstrate the formation of bicolour structures with a mushroom-like shape. Their immersed portion (the cap) was exclusively involved in the uptake and reduction of gold precursor, acquiring the typical purple colour of Au NPs; whereas, the emerged portion (the stem) did not participate in the in situ synthesis and retained the white colour of calcium alginate. Moreover, we noted that the localized growth of Au NPs was strongly related to the initial amount of gold precursor. In fact for high concentrations, the gold ions were just encapsulated inside the gel matrix and no reduction was observed in the wet structures neither in the cap nor in the stem. The reported procedure is simple and capable of directing the synthesis of Au NPs into selected areas of the alginate matrix, making possible the fabrication of a novel class of alginate structures with an anisotropic character and potential applications in the area of drug delivery and biosensors

Surprising High Hydrophobicity of Polymer Networks from Hydrophilic Components

We report a simple and inexpensive method of fabricating highly hydrophobic novel materials based on interpenetrating networks of polyamide and poly­(ethyl cyanoacrylate) hydrophilic components. The process is a single-step solution casting from a common solvent, formic acid, of polyamide and ethyl cyanoacrylate monomers. After casting and subsequent solvent evaporation, the in situ polymerization of ethyl cyanoacrylate monomer forms polyamide-poly­(ethyl cyanoacrylate) interpenetrating network films. The interpenetrating networks demonstrate remarkable waterproof properties allowing wettability control by modulating the concentration of the components. In contrast, pure polyamide and poly­(ethyl cyanoacrylate) films obtained from formic acid solutions are highly hygroscopic and hydrophilic, respectively. The polymerization of ethyl cyanoacrylate in the presence of polyamide promotes molecular interactions between the components, which reduce the available hydrophilic moieties and render the final material hydrophobic. The wettability, morphology, and thermo-physical properties of the polymeric coatings were characterized. The materials developed in this work take advantage of the properties of both polymers in a single blend and above all, due to their hydrophobic nature and minimal water uptake, can extend the application range of the individual polymers where water repellency is required

Self-Cleaning Organic/Inorganic Photo-Sensors

We present the fabrication of a multifunctional, hybrid organic–inorganic micropatterned device, which is capable to act as a stable photosensor and, at the same time, displaying inherent superhydrophobic self-cleaning wetting characteristics. In this framework several arrays of epoxy photoresist square micropillars have been fabricated on n-doped crystalline silicon substrates and subsequently coated with a poly­(3-hexylthiophene-2,5-diyl) (P3HT) layer, giving rise to an array of organic/inorganic p–n junctions. Their photoconductivity has been measured under a solar light simulator at different illumination intensities. The current–voltage (<i>I</i>–<i>V</i>) curves show high rectifying characteristics, which are found to be directly correlated with the illumination intensity. The photoresponse occurs in extremely short times (within few tens of milliseconds range). The influence of the interpillar distance on the <i>I</i>–<i>V</i> characteristics of the sensors is also discussed. Moreover, the static and dynamic wetting properties of these organic/inorganic photosensors can be easily tuned by changing the pattern geometry. Measured static water contact angles range from 125° to 164°, as the distance between the pillars is increased from 14 to 120 μm while the contact angle hysteresis decreases from 36° down to 2°

Magnetic-Field-Induced Formation of Superparamagnetic Microwires in Suspension

We demonstrate the formation of stable magnetic microwires (MWs) in solution starting from a highly diluted solution of monomer–thermal initiator–superparamagnetic nanoparticles (SMNPs). Under an external magnetic field (MF) the SMNPs get closely packed into wire-like assemblies that become permanently linked due to simultaneous thermal polymerization of the monomer. As the SMNPs assemble in the form of wires under MF, the concentration of the monomer chains adsorbed onto them increases in the near proximity of these assemblies, promoting the polymerization process during heating. This combined process causes the permanent bonding among the SMNPs, forming smooth MWs with metallic character. Detailed microscopic and spectroscopic studies reveal the mechanism of the process and designate the importance of the external MF, the thermal polymerization, and the high dilution factor of the reaction solution for the formation of free-standing uniform wires with controlled size. This method leads to a novel approach to form long magnetic wires with smooth contour and regular shape, which can be used in various fields of applications like in biomedicine, chemistry, fluidics, etc

The antennal lobes reveal abnormalities in <i>PINK1^B9</i> mutants.

<p>ALs were stained for the expression of Bruchpilot protein. Panel A: Confocal micrographs of a frontal view of a couple of ALs (indicated by the arrow heads), with their well-defined glomeruli in WT and the mutant (Scale bar = 50 µm). <b>B,C:</b> The volume rendering for the monoclonal nc82 antibody-stained AL as seen from a frontal view in a WT (B) and in a <i>PINK1^B9</i> mutant (C) (scale bars = 30 µm). Ten specimens in the age range of 3–10 days for each strain were analyzed; the volumes measured were averaged and the statistical differences evaluated. Mean values ± S.E. are reported in C: no significant difference was detected (<i>P</i>>0.05). E,F: Higher magnification photomicrographs of a single AL in WT and <i>PINK1^B9</i> mutant respectively (scale bars = 20 µm). The latter reproducibly displays a less intensive staining and the glomeruli are not as clearly defined as in the WT. The gray scale value, taken as the index of intensity, was measured on ALs from binarized stacks of images (n = 10 for each strain). Mean values ± S.E. for both WT and <i>PINK1^B9</i> mutants are shown in G. Statistical evaluation of the data shows that the staining intensity in <i>PINK1^B9</i> is significantly lower compared to WT; (*significantly different from its matching value; <i>P</i><0.05).</p

Western blot analysis of <i>PINK1^B9</i> heads shows a reduced expression of the bruchpilot protein.

<p><b>A:</b> Western blot analysis of adult head homogenate from WT and <i>PINK1^B9</i> flies showing the nc82-labeled Bruchpilot protein band (BRP, top) and the loading control Tubulin (bottom). The amount of Bruchpilot protein was quantified by analyzing the intensity of the bands on the autoradiogram with a densitometer. Data were normalized by dividing optical density of the bands corresponding to Bruchpilot protein by that of the band for α-Tubulin. <b>B:</b> Statistical evaluation of the densitometric data shows that the expression of Bruchpilot protein in <i>PINK1^B9</i> is significantly lower compared to WT (*significantly lower than its matching value; <i>P</i><0.05).</p

Mitochondria within the presynaptic boutons in the antennal lobes present structural alterations in <i>PINK1^B9</i>mutants.

<p>Transmission electron microscopy (TEM) images of mitochondria within the olfactory bulbs of WT and <i>PINK1^B9 Drosophila</i>. A: Two mitochondria in a presynaptic bouton of a WT (scale bar = 200 µm). The regular array of mitochondrial cristae (arrowheads) is surrounded by an electron-dense matrix. B: A mitochondrion in a presynaptic bouton of a <i>PINK1^B9</i> mutant (scale bar = 100 µm). The mitochondrion presents a swelling on its external membrane (arrow) and the mitochondrial cristae are highly degenerated (asterisk). C: a conventional mitochondrion in a WT (scale bar = 200 µm). The regular electron-dense matrix surrounds the mitochondrial cristae (asterisk). D: The abnormal mitochondrial morphology in a <i>PINK1^B9</i> mutant. The mitochondrial cristae are fragmented (arrowhead). E: The abnormal mitochondrial morphology in a <i>PINK1^B9</i> mutant (scale bar = 100 µm). Remnants of the mitochondrial cristae are visible within the mitochondrial matrix (scale bar = 100 µm).</p

Lifespan in wild type and <i>PINK^B9</i> mutant adults.

<p>The graph shows the survival rate observed in wild type and <i>PINK1^B9</i> mutants. <i>PINK1^B9</i> had a reduced lifespan compared to WT.<i>PINK1^B9</i> flies started to die dramatically at the 15^th days after eclosion with 50% of flies being dead after 30 days (P<0.0001).</p