Antonella Milella

Deposition of super-hydrophobic fluorocarbon coatings in modulated RF glow discharges

Superhydrophobic coatings were deposited in modulated RF glow discharges fed with tetrafluorothylene. Such coatings are characterized by a high fluorination degree, ribbon-like randomly distributed surface microstructures, and a certain crystallinity. Combined high fluorination degree and surface texture/roughness leads to the super hydrophobic behaviour, as attested by water contact angle values of 150° and more. The coatings were characterized by means of XPS, FT-IR and X-ray diffraction, while time resolved optical emission spectroscopy was utilized to investigate the plasma phase.

Morphological and structural study of plasma deposited fluorocarbon films at different thicknesses

The growth of fluorocarbon thin films has been obtained by continuous and modulated r.f. plasmas fed with C2F4. The kinetics surface morphology of the coatings has been investigated and analyzed on films of various thicknesses. Such a study has allowed the evolution of structures in size and shape to be followed. Specifically, it has been observed that modulated plasmas with the proper duty cycles (⩽7%) lead to the formation of micrometer-long ribbon-shaped nanostructures. The precursors of the ribbons are nuclei that align into a spiral-mimic. Highly nanostructured films with an optimal thickness and ribbon density exhibit a super-water repellent surface with contact angles up to 170°. The surface roughness and smoothing of fluorocarbon films are strongly affected by the modulated and continuous plasmas, respectively.

Cell Adhesion on Nanotextured Slippery Superhydrophobic Substrates

In this work, the response of Saos2 cells to polymeric surfaces with different roughness/density of nanometric dots produced by a tailored plasma-etching process has been studied. Topographical features have been evaluated by atomic force microscopy, while wetting behavior, in terms of water-surface adhesion energy, has been evaluated by measurements of drop sliding angle. Saos2 cytocompatibility has been investigated by scanning electron microscopy, fluorescent microscopy, and optical microscopy. The similarity in outer chemical composition has allowed isolation of the impact of the topographical features on cellular behavior. The results indicate that Saos2 cells respond differently to surfaces with different nanoscale topographical features, clearly showing a certain inhibition in cell adhesion when the nanoscale is particularly small. This effect appears to be attenuated in surfaces with relatively bigger nanofeatures, though these express a more pronounced slippery/dry wetting character.

Palladium‐Catalyzed Cross‐Coupling of Styrenes with Aryl Methyl Ketones in Ionic Liquids: Direct Access to Cyclopropanes

The combined use of Pd(OAc)2 , Cu(OAc)2 , and dioxygen in molten tetrabutylammonium acetate (TBAA) promotes an unusual cyclopropanation reaction between aryl methyl ketones and styrenes. The process is a dehydrogenative cyclizing coupling that involves a twofold CH activation at the α-position of the ketone. The substrate scope highlights the flexibility of the catalyst; a reaction mechanism is also proposed.

From Low-k to Ultralow-k Thin-Film Deposition by Organosilicon Glow Discharges

Continuous and modulated discharges, fed with divinyltetramethyldisiloxane mixed with oxygen and argon, were used to deposit carbon-doped silica-like (SiCOH) low-k to ultralow-k films. The effect of various process parameters on the dielectrical and thermal properties of films as well as on their chemical composition were investigated. As deposited, the SiCOH films exhibited dielectric constants from 4.45 to 2.70. Thermal annealing in the 400-450°C temperature range was found to be necessary to reach ultralow-permittivity values, but the temperature must be controlled in order to prevent an excessive collapse of the silicate matrix, which leads to poor thermal stability and mechanical properties. Lowering the oxygen content in the discharge allowed for a continuous decrease in k values down to 2.32 when low radio frequency power was used, with a limited film thickness loss upon annealing of 11%. Fourier transform infrared spectra of ultralow-k film exhibited intense absorptions from C-containing moieties, like CH x and Si(CH 3 ) x . Upon annealing at 400°C, the organic content considerably decreases, though the loss of Si(CH 3 ) x groups is quite limited. Thermogravimetric analysis coupled with mass spectrometry revealed that during thermal treatment, silicon-containing fragments were lost from the matrix along with hvdrocarbon ones.

Spray-dried mucoadhesives for intravesical drug delivery using N-acetylcysteine- and glutathione-glycol chitosan conjugates.

UNLABELLED This work describes N-acetylcysteine (NAC)- and glutathione (GSH)-glycol chitosan (GC) polymer conjugates engineered as potential platform useful to formulate micro-(MP) and nano-(NP) particles via spray-drying techniques. These conjugates are mucoadhesive over the range of urine pH, 5.0-7.0, which makes them advantageous for intravesical drug delivery and treatment of local bladder diseases. NAC- and GSH-GC conjugates were generated with a synthetic approach optimizing reaction times and purification in order to minimize the oxidation of thiol groups. In this way, the resulting amount of free thiol groups immobilized per gram of NAC- and GSH-GC conjugates was 6.3 and 3.6mmol, respectively. These polymers were completely characterized by molecular weight, surface sulfur content, solubility at different pH values, substitution and swelling degree. Mucoadhesion properties were evaluated in artificial urine by turbidimetric and zeta (ζ)-potential measurements demonstrating good mucoadhesion properties, in particular for NAC-GC at pH 5.0. Starting from the thiolated polymers, MP and NP were prepared using both the Büchi B-191 and Nano Büchi B-90 spray dryers, respectively. The resulting two formulations were evaluated for yield, size, oxidation of thiol groups and ex-vivo mucoadhesion. The new spray drying technique provided NP of suitable size (<1μm) for catheter administration, low degree of oxidation, and sufficient mucoadhesion property with 9% and 18% of GSH- and NAC-GC based NP retained on pig mucosa bladder after 3h of exposure, respectively. STATEMENT OF SIGNIFICANCE The aim of the present study was first to optimize the synthesis of NAC-GC and GSH-GC, and preserve the oxidation state of the thiol moieties by introducing several optimizations of the already reported synthetic procedures that increase the mucoadhesive properties and avoid pH-dependent aggregation. Second, starting from these optimized thiomers, we studied the feasibility of manufacturing MP and NP by spray-drying techniques. The aim of this second step was to produce mucoadhesive drug delivery systems of adequate size for vesical administration by catheter, and comparable mucoadhesive properties with respect to the processed polymers, avoiding thiolic oxidation during the formulation. MP with acceptable size produced by spray-dryer Büchi B-191 were compared with NP made with the apparatus Nano Büchi B-90.

Chemical functionalization of N-doped carbon nanotubes: a powerful approach to cast light on the electrochemical role of specific N-functionalities in the oxygen reduction reaction

In this paper, we describe the combination of two different synthetic approaches to carbon nanotube N-decoration/doping: the chemical functionalization with tailored N-pyridinic groups and the classical Chemical Vapor Deposition (CVD) technique. Accordingly, CVD-prepared N-doped CNMs (NMWs) and their N-decorated (chemically functionalized) counterparts (NMW@N1,2) have been prepared and used as metal-free electrocatalysts for the oxygen reduction reaction (ORR). It has been demonstrated that chemical functionalization occurs on the NMW surface sites responsible for their inherent electrochemical properties and “switches them off”. As a result, the ORR promoted by NMW@N1,2 is fully controlled by the appended N-heterocycles. A comparative analysis of N-functionalized samples and N-doped (CVD prepared) materials is used to foster the hypothesis of a unique N-configuration (N-pyridinic) responsible for the overall electrochemical performance in NMWs. In addition to that, original electrochemical insights unveiled during the study are discussed and the truly metal-free action of NMW in ORR catalysis is demonstrated.

Plasma deposited Pt-containing hydrocarbon thin films as electrocatalysts for PEM fuel cell

High performance electrocatalytic hydrocarbon thin films containing Pt nano-clusters are deposited by simultaneous plasma polymerization of ethylene and sputtering of a Pt target. The proposed synthetic approach largely simplifies the PEMFC electrocatalyst fabrication process with respect to conventional methods. The deposition of the hydrocarbon matrix provides the mechanical support and electronic continuity, ensuring a uniform metal dispersion, avoiding Pt nanoparticle agglomeration. The Pt catalyst is dispersed as small vertically stacked clusters with size less than 10 nm in columnar thin (250–500 nm) films. PEMFC testing with plasma deposited 500 nm thick film and 0.513 mg cm−2 Pt load as anodic electrocatalyst led to a maximum reproducible power density as high as 300 mW cm−2.

Plasma Assisted Surface Modification Processes for Biomedical Materials and Devices

This contribution reviews cold plasma processes that are investigated and utilized in academic and technological fields related to Life Sciences, in particular for tailoring surface composition and morphology of materials of different utilization in Medicine and Biology for implants, prostheses, biosensors, devices and scaffolds for tissue engineering. The final goal of the research in this field is, in general, to achieve the capability of driving at will the behaviour (adhesion, growth, morphology, physiology, etc.) of cells and biological tissues in vitro and in vivo at the surface of modified materials.

Sorption properties of an amorphous hydroxo titanate towards Pb2+, Ni2+, and Cu2+ ions in aqueous solution

ABSTRACT Titanates may be selectively used as inorganic adsorbents for heavy metal ions owing to their stability and fast adsorption kinetics. Nevertheless, the synthesis of such materials usually requires extreme reaction conditions. In this work, a new titanium-based material was rapidly synthesized under mild laboratory conditions. The obtained amorphous hydroxo titanate was tested for heavy metal sorption through kinetic and equilibrium batch tests, which indicated that the new material had high adsorption rates and adsorption capacities towards Cu2+, Ni2+ and Pb2 ions. Adsorption kinetics were pseudo-second order, and equilibrium data fitted the Langmuir isotherm model. The calculated maximum adsorption capacities of Cu2+, Ni2+ and Pb2+ in deionized water were around 1 mmol g−1, and they decreased for Cu2+ and Ni2+ in the presence of Na+, Ca2+ and Mg2+ ions, whereas the alkali metal ions did not influence Pb2+ uptake. The efficiency of adsorption and recovery of lead ions were evaluated through column dynamic tests, by feeding the column with groundwater and tap water spiked with Pb2+. The high performance of the hydroxo titanate over several cycles of retention and elution suggested that the product is potentially useful for the solid phase extraction of lead at trace levels in natural water samples, with potential use in metal pre-concentration for analytical applications.