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We have investigated the influence on adhesion and proliferation of NIH 3T3 fibroblasts of the surface morphology of cluster assembled carbon films deposited by Supersonic Cluster Beam Deposition. Nanostructured carbon films exhibit a multi-scale morphology, which resembles the surface structure of the extracellular matrix, and possess a high specific area, while being relatively smooth at all scales. Correlations between measured morphological parameters and adaptive cell response have been brought out. High specific area and smoothness appear to conceivably favour both the early attachment of plated cells and the long-term survival of adherent cells. Moreover, nano-structured carbon films affect the cells morphology as well as the extension and the number of the focal contacts.

We used atomic force microscopy (AFM) to characterize the plasma membrane of Xenopus laevis oocytes. The samples were prepared according to novel protocols, which allowed the investigation of the extra- and intracellular sides of the membrane, both of which showed sparsely distributed spherical-like protrusions. Regions with comparably sized and densely packed structures arranged in an orderly manner were visualized and dimensionally characterized. In particular, two different arrangements, hexagonal and square packing, were recognizable in ordered regions. The lateral dimension of structures visualized on the external side had a normal distribution centered on 25.5 ± 0.3 nm (mean value ± SE), whereas that on the intracellular side showed a normal distribution centered on 30.2 ± 0.8 nm. The height of the protrusions was 2–5 nm on the external side and 1–3 nm on the intracellular side. The mean number of structures on the external and intracellular sides of the plasma membrane was about 1000 μm−2 and 850 μm−2 respectively. Trypsin treatment greatly decreased the size of the membrane protrusions, thus confirming the proteic nature of the structures. These results show that AFM is a useful tool for structural characterization of proteins in a native eukaryotic membrane. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc.

Nanostructured carbon thin films can be grown by deposition of cluster beams produced in supersonic expansions. By using a pulsed microplasma cluster source and by exploiting aerodynamic focusing effects typical of supersonic expansions, the structure and the properties of the films can be controlled by varying the cluster mass distribution prior to deposition. Nanocomposite films can be produced by co-depositing carbon clusters and metallic nanoparticles. The films have been characterized by various spectroscopic techniques and tested in view of applications for field emission, supercapacitors, gas sensing. The possibility of patterning cluster-assembled carbon films by shadow masking or by ultraviolet photon irradiation suggests interesting perspective for the integration of nanostructured carbon films on microfabricated devices and for the production of components for an all-carbon electronics.

The effects of electron beam or gamma-irradiation on technological performances (capsule hardness, expressed as deforming work and dissolution time) of empty 2-shell capsules made of gelatin or hydroxypropylmethylcellulose (HPMC) were studied. Capsule structural changes induced by radiation treatment were investigated by capillary viscometry and atomic force microscopy (AFM). The capsules were irradiated in the air at 5, 15, and 25 kGy. The deforming work of nonirradiated HPMC capsules (0.06 +/- 0.01 J) was lower than that of gelatin capsules (0.10 +/- 0.01 J). The dissolution time of the HPMC capsules (414 +/- 33 seconds) was slightly higher than that determined for gelatin hard capsules (288 +/- 19 seconds). The hardness and dissolution time of gelatin and HPMC capsules were not significantly influenced by the irradiation type and the applied irradiation dose. As the viscometry analyses are concerned, irradiation caused a reduction of the intrinsic viscosity and water and dimethyl sulfoxide solvent power in both the cases. AFM analysis showed that the radiation treatment did not appreciably affect the surface roughness of the samples nor induce structural changes on capsule surface. However, measurements of force-distance curves pointed out a qualitative parameter for the identification of the irradiated capsules. On the bases of these preliminary results, empty gelatin or HPMC hard capsules can be sanitized/sterilized by ionizing radiation.

We have developed a method for the quantitative evaluation of the chemisorbed fraction of hydrogen in nanostructured carbon films using Near Edge X-ray Absorption Spectroscopy (NEXAFS). In the carbon K-edge spectrum the peak related to carbon bonded to hydrogen is assumed to be correlated with the amount of hydrogen bonded to carbon. This assumption is supported by a comparative analysis of gas-phase hydrocarbons obtained via Electron Energy Loss Spectroscopy (EELS). We applied the method to nanostructured carbon (ns-C) films synthesized by supersonic cluster beam deposition. The evaluated quantity of chemisorbed hydrogen in different samples exposed to molecular hydrogen (pressure of 0.12 MPa, for 3 hours at room temperature) is ∼1.5 wt.%.

Nanostructured CNx thin films were prepared by supersonic cluster beam deposition (SCBD) and systematically characterized by transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The incorporation of nitrogen in the films (0

A multi‐scale investigation of nanostructured carbon films has been performed by means of inelastic light scattering (Raman and Brillouin scattering). Carbon films with different nano‐ and mesostructure have been deposited from supersonic cluster beams in a low energy deposition regime by exploiting aerodynamic focusing effects. Acoustic phonon propagation in the porous amorphous structure, where disorder acts as a damping factor, is investigated by Brillouin scattering. Depending on the nano‐ and meso‐structure, acoustic phonons can either propagate along the medium, which acts as an elastic continuum at the meso‐scale (i.e., hundreds of nm), or turn to overdamped oscillations localized by the structural disorder. Nevertheless, we show that it is always possible to measure the elastic constants of thin and porous films, when other techniques (e.g., nano‐indentation) become critical. At the nano‐scale, Raman scattering measurements show the typical structure of an amorphous carbon, where the stru...

We studied the electronic structure of nanostructured C films produced by ultrasonic cluster beam deposition with the intention to find out the bonding configuration of the C network and to determine the modification induced by transition metal cluster inclusion in the film. Exploiting the energy and spatial resolution of the Spectromicroscopy beamline at Elettra Synchrotron, we were able to follow the valence band features depicted in 95.0 eV-excited photoemission spectra with a 0.5 μm lateral resolution. The spectroscopic results allowed to conclude that nanostructured C films have a mixed sp2/sp3 bond configuration and an amorphous-like structure and that those features are uniformly distributed in the film. The inclusion of metal cluster (Ni, Ti and Mo) in the film strongly modifies the valence band spectra. The surface stoichiometry of the embedded metal clusters and the keeping of their metallic nature are determined by a detailed analysis of the spatial dependence of the ultraviolet photoemission spectroscopy (UPS) spectra and by a comparison with previous studies on metal-carbide and -oxide surfaces.

We have produced nanostructured titanium dioxide thin films by supersonic cluster beam deposition. The as-deposited films have a nanocrystalline or amorphous structure depending on the mass distribution of the precursor clusters. This can be controlled by aerodynamic separation effects typical of supersonic expansions. On thermal annealing at temperatures from 400 to 800 °C in ambient atmosphere, amorphous-to-anatase and anatase-to-rutile phase transitions have been observed. The nanostructure and microstructure evolution of the film upon annealing has been characterized by atomic force microscopy and transmission electron microscopy. The influence of the precursor clusters in the evolution of the film nanostructure at high temperatures has been demonstrated. This observation opens up new perspectives for batch fabrication of devices based on cluster-assembled materials.

Inclusions of metals in the growth process of carbon cluster assembled materials (ns-C) induce modifications in the structural and electronic properties of the material. A novel pulsed microplasma cluster source (PMCS) is able to deliver highly intense, collimated and stable beams suitable for producing bulk quantities of cluster-assembled nanocomposite films. Loading of metal nanoparticles into carbon cluster based films is obtained either by mixing a gas phase metallorganic compound with the carrier gas (He) before entering into the source (for example molybdenum (V) isopropoxide), or by using a double component sputtering target (metal (Ti, Ni)/graphite). The study of film morphology on nanometer scale, carried out by transmission electron microscopy (TEM), reveals the dispersion in a ns-C matrix of metallic particles and, in the case of molybdenum containing films, also of carbide particles. Spatially resolved ultraviolet photoemission spectroscopy confirms the segregation of metal particles and exhibits evident anisotropy in the Mo:ns-C films, mainly ascribable to the formation of carbide nanoparticles.

We have exploited the possibility of obtaining SiC by annealing at selected increasing temperatures cluster-assembled carbon films deposited in situ by a supersonic beam onto Si(1 0 0)-(2 x 1) substrates. We measured the evolution of the valence bands and of the Si 2p and C 1s core level spectra to monitor the thermal induced effects in the atomic concentrations and the electronic structure at the interface. Our results indicate that at the interface Si-C bonds are already formed at 700 degreesC, a temperature that is significantly lower (approximate to 50 degreesC) than found in literature by using other C-based precursors for SiC growth on Si surfaces. Supersonic carbon cluster beam deposition seems to be promising for the growth of SiC films on Si surfaces with improved interface quality.

We present and discuss the design and operation of a compact ultrahigh vacuum compatible apparatus for the production and deposition of supersonic cluster beams. The apparatus is equipped with a pulsed microplasma cluster source capable of providing supersonic beams of high stability and intensity. The cluster mass distribution can be analyzed by a two-stage time-of-flight mass spectrometer. The transportability and versatility of the apparatus make the system well suited to perform in situ studies on both gas phase clusters and cluster assembled materials using different characterization facilities. The performances of the system have been tested by scanning tunneling microscopy and photoemission spectroscopy experiments on cluster-assembled carbon films.

The potential of the 3D cell culture approach for creating in vitro models for drug screening and cellular studies, has led to the development of hydrogels that are able to mimic the in vivo 3D cellular milieu. To this aim, synthetic polymer-based hydrogels, with which it is possible to fine-tune the chemical and biophysical properties of the cell microenvironment, are becoming more and more acclaimed. Of all synthetic materials, poly(amidoamine)s (PAAs) hydrogels are known to have promising properties. In particular, PAAs hydrogels containing the 2,2-bisacrylamidoacetic acid-agmatine monomeric unit are capable of enhancing cellular adhesion by interacting with the RGD-binding αVβ3 integrin. The synthesis of a new photocrosslinkable, biomimetic PAA-Jeffamine®-PAA triblock copolymer (PJP) hydrogel is reported in this paper with the aim of improving the optical, biocompatibility and cell-adhesion properties of previously studied PAA hydrogels and providing an inexpensive alternative to the RGD peptide based hydrogels. The physicochemical properties of PJP hydrogels are extensively discussed and the behavior of 2D and 3D cell cultures was analyzed in depth with different cell types. Moreover, cell-laden PJP hydrogels were patterned with perfusable microchannels and seeded with endothelial cells, in order to investigate the possibility of using PJP hydrogels for fabricating cell laden tissue-like micro constructs and microfluidic devices. Overall the data obtained suggest that PJP could ultimately become a useful tool for fabricating improved in vitro models in order to potentially enhance the effectiveness of drug screening and clinical treatments.

Despite significant progresses were achieved in tissue engineering over the last 20 years, a number of unsolved problems still remain. One of the most relevant issues is the lack of a proper vascularization that is limiting the size of the engineered tissues to smaller than clinically relevant dimensions. Sacrificial molding holds great promise to engineered construct with perfusable vascular architectures, but there is still the need to develop more versatile approaches able to be independent of the nature and dimensions of the construct. In this work we developed a versatile sacrificial molding technique for fabricating bulk, cell-laden and porous scaffolds with embedded vascular fluidic networks. These branched fluidic architectures are created by highly resistant thermoplastic sacrificial templates, made of poly(vinyl alcohol), representing a remarkable progress in manufacturability and scalability. The obtained architecture, when perfused in bioreactor, has shown to prevent the formation of a necrotic core in thick cell-laden constructs and enabled the rapid fabrication of hierarchically branched endothelium. In conclusion we demonstrate a novel strategy towards the engineering of vascularized thick tissues through the integration of the PVA-based microfabrication sacrificial approach and perfusion bioreactors. This approach may be able to scale current engineered tissues to clinically relevant dimensions, opening the way to their widespread clinical applications.

Nanostructured carbon thin films have been grown by deposition of cluster beams produced in supersonic expansions. The structure and morphology of the films can be controlled by varying the cluster mass distribution prior to deposition. The films have been characterized by Raman spectroscopy and atomic force microscopy. These characterizations show the influence of deposition condition on the surface roughness and the onset of scale-invariant morphology on a dimension domain extending from the nanometer up to the micrometer. The cluster beam deposition method shows very promising features in view of the large-scale growth of nanostructured films with novel functional and structural properties.

Near-edge X-ray absorption fine structure (NEXAFS) measurements have been made on carbon nitride films containing as much as 44 at.% of nitrogen. The films have been synthesized by dual ion beam deposition (IBD) bombarding a carbon target with low-energy nitrogen ions at varying nitrogen beam energies and substrate temperatures ranging from the liquid nitrogen temperature up to 400°C. The structural changes induced by the reduction of the temperature have been previously investigated [Hammer et al., J. Vac. Sci. Technol. A 15 (1) (1997) 107; Baker et al., Surf. Coat. Technol. 97 (1997) 544]. The transition from a predominantly sp2/sp3 CN amorphous arrangement to a more polymer-like structure has been confirmed and more deeply examined by X-ray absorption spectroscopy. In particular, for samples deposited at liquid nitrogen temperature, a relevant reduction of sp2 CC fraction has been detected. Moreover, the condensation on the growing film surface of hydrogen containing species (i.e. HCN) has been well identified by the appearance of the CH∗ peak.

In this paper we report on the electrodeposition process from a highly acidic aqueous sulphate electrolyte and discuss the relationships between electrochemical kinetics and crystalline structure of the electrodeposits. The electrochemical kinetics were studied by voltammetric and potentiostatic methods, showing the peculiarities of the cathodic process of highly acidic baths, leading - under suitable plating conditions - to the removal of the Te excess which is typical for the ZnTe electrodeposition systems reported in the literature. Potential transient techniques and scanning electron microscopy (SEM) imaging were used to study the nucleation. They showed that the nucleation process is instantaneous. The crystalline structure of the deposits was studied by X-ray diffraction (XRD), revealing the possibility of growing directly cubic ZnTe films under suitable electrochemical conditions. A minor amount of Te can form at the surface as a result of etching by the electrodeposition bath. Structural data were complemented by X-ray photoelectron spectroscopy (XPS) analyses and compositional measurements by energy dispersive spectrometry (EDS).

The preferential sputtering of S from bulk MoS2 standard samples exposed to 3 keV Ar+ ion bombardment has been studied by XPS. The MoSx stoichiometry decreases from MoS2 to MoS1.12 with a concomitant reduction in the Mo 3d5/2 binding energy from 229.25 to 228.35 eV. The altered layer extends to a depth of 3.8 nm and is proposed to consist of a single amorphous MoSx phase in which Mo has a varying number of nearest neighbour S atoms. Using peak positions alone it is possible to determine the MoSx stoichiometry to an accuracy of x±0.1 from a plot of MoSx stoichiometry against (Mo 3d5/2–S 2p3/2) binding energy. The results are of strong current interest for coating analysis applications as MoS2 is a compound capable of providing low friction properties when incorporated into hard coatings.

Bombarding a carbon target with low-energy nitrogen ions causes the release of neutral carbon atoms (physical sputtering) and volatile carbon nitride compounds (chemical sputtering) with relative yields dependent on the energy of the nitrogen beam. The chemically sputtered species are volatile and can be condensed on the substrate by reducing its temperature. Carbon nitride films have been deposited at varying nitrogen beam energies and substrate temperatures in a dual ion beam deposition chamber. Films were grown both with and without the presence of an additional assisting nitrogen beam. Reduction of the substrate temperature in conjunction with low sputter beam voltages (

The thermally agglomerated Au/Si(111) interface has been studied by means of laterally resolved photoemission by exploiting the ultra-high brightness of the ELETTRA synchrotron radiation source. The interface has been evaluated in terms of chemical maps and core level spectra acquired from selected points of the specimen surface. The variety of distinct chemical environments local to element-specific sites has thereby been clarified with an unprecedented level of resolution at both the islands and the two-dimensional superstructure terminating the Si crystal.

Activation of glial cells, including astrocytes and microglia, has been implicated in the inflammatory responses underlying brain injury and neurodegenerative diseases including Alzheimer's and Parkinson's diseases. The classic activation state (M1) is characterized by high capacity to present antigens, high production of nitric oxide (NO) and reactive oxygen species (ROS) and proinflammatory cytokines. Classically activated cells act as potent effectors that drive the inflammatory response and may mediate detrimental effects on neural cells. The second phenotype (M2) is an alternative, apparently beneficial, activation state, more related to a fine tuning of inflammation, scavenging of debris, promotion of angiogenesis, tissue remodeling and repair. Specific environmental chemical signals are able to induce these different polarization states. We provide here evidence that nanostructured substrates are able, exclusively in virtue of their physical properties, to push microglia toward the proinflammatory activation phenotype, with an efficacy which reflects the graded nanoscale rugosity. The acquisition of a proinflammatory phenotype appears specific for microglia and not astrocytes, indicating that these two cell types, although sharing common innate immune responses, respond differently to external physical stimuli.

Nucleus pulposus (NP) tissue damage can induce detrimental mechanical stresses and strains on the intervertebral disc, leading to disc degeneration. This study demonstrates the potential of a novel, photo-curable, injectable, synthetic polymer hydrogel (pHEMA-co-APMA grafted with polyamidoamine (PAA)) to encapsulate and differentiate human mesenchymal stem cells (hMSC) towards a NP phenotype under hypoxic conditions which could be used to restore NP tissue function and mechanical properties. Encapsulated hMSC cultured in media (hMSC and chondrogenic) displayed good cell viability up to day 14. The genotoxicity effects of ultraviolet (UV) on hMSC activity confirmed the acceptability of 2.5min of UV light exposure to cells. Cytotoxicity investigations revealed that hMSC cultured in media containing p(HEMA-co-APMA) grafted with PAA degradation product (10% and 20%v/v concentration) for 14days significantly decreased the initial hMSC adhesion ability and proliferation rate from 24hrs to day 14. Successful differentiation of encapsulated hMSC within hydrogels towards chondrogenesis was observed with elevated expression levels of aggrecan and collagen II when cultured in chondrogenic media under hypoxic conditions, in comparison with culture in hMSC media for 14days. Characterization of the mechanical properties revealed a significant decrease in stiffness and modulus values of cellular hydrogels in comparison with acellular hydrogels at both day 7 and day 14. These results demonstrate the potential use of an in vivo photo-curable injectable, synthetic hydrogel with encapsulated hMSC for application in the repair and regeneration of NP tissue.

Poly(amido-amine) (PAA) hydrogels containing the 2,2-bisacrylamidoacetic acid-4-amminobutyl guanidine monomeric unit have a known ability to enhance cellular adhesion by interacting with the arginin–glycin–aspartic acid (RGD)-binding αVβ3 integrin, expressed by a wide number of cell types. Scientific interest in this class of materials has traditionally been hampered by their poor mechanical properties and restricted range of degradation rate. Here we present the design of novel biocompatible, RGD-mimic PAA-based hydrogels with wide and tunable degradation rates as well as improved mechanical and biological properties for biomedical applications. This is achieved by radical polymerization of acrylamide-terminated PAA oligomers in both the presence and absence of 2-hydroxyethylmethacrylate. The degradation rate is found to be precisely tunable by adjusting the PAA oligomer molecular weight and acrylic co-monomer concentration in the starting reaction mixture. Cell adhesion and proliferation tests on Madin–Darby canine kidney epithelial cells show that PAA-based hydrogels have the capacity to promote cell adhesion up to 200% compared to the control. Mechanical tests show higher compressive strength of acrylic chain containing hydrogels compared to traditional PAA hydrogels.

Electrospun polycaprolactone (PCL) layers with sub-micron fibres arranged in random, semi-aligned and aligned manners were prepared and their anisotropic mechanical property were further characterised at various stretching angle. Proof of principle study was carried out to assess biocompatibility of electrospun layers with human mesenchymal stem cells (hMSCs). Cell adhesion, viability and orientation outcomes showed that aligned PCL nano-fibers can be applied as a template to guide the alignment of hMSCs and could be a promising scaffold for tissue engineering of anisotropic annulus fibrosus in spinal inter-vertebral disc.

Loss of skeletal muscle tissue caused by traumatic injury or damage due to myopathies produces a deficit of muscle function for which there is still no clinical treatment. Transplantation of myogenic cells, themselves or combined with materials, has been proposed to increase the regenerative capacity of skeletal muscle but it is hampered by many limitations, such as low cell survival and engraftment or immunological reaction and low biocompatibility of the exogenous materials. Recently, myoblast sheet engineering, obtained with thermoresponsive culture dishes, has attracted attention as a new technique for muscle damage treatment. For this purpose, a series of thermoresponsive hydrogels, constituted by poly(N-isopropylacrylamide-co-2-hydroxyethylmethacrylate) [p(NIPAAM-co-HEMA)] were synthesized by a simple and inexpensive free-radical polymerization of the two co-monomers with a redox initiator. Different ratios of N-isopropylacrylamide (NIPAAm) and 2-hydroxyethylmethacrylate (HEMA) have been examined to evaluate the effects on physicochemical, mechanical and optical hydrogel properties. The murine muscle cell line C

Carbon nitride films were synthesized by ion beam assisted sputtering. A graphite target was sputtered by argon or nitrogen ions and the growing film was simultaneously bombarded by a focused nitrogen ion beam of energies between 100–800 eV at 100 and 400 °C. It has been found that film growth occurs only if the ion-to-atom arrival ratio is smaller than a critical value of about 1.8 and it appears to be almost independent of the assisting beam energy. This effect, limiting the film growth, is a consequence of a chemical reaction between carbon and nitrogen forming volatile CN compounds. Experimental evidence was obtained by monitoring the gas evolved during the deposition process with a quadrupole gas analyzer. The maximum value of nitrogen content measured by Auger electron spectroscopy was about 35 at.%. All films were investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The latter technique shows a preferential bonding of N to sp 3 -hybridized C. Hardness measurements with values up to 20 GPa were measured using a depth sensing nanoindenter.

Nanostructured carbon and carbon–TiOx films produced by supersonic cluster beam deposition have been characterized by spatially resolved (0.5 μm lateral resolution) photoemission spectroscopy with synchrotron light. We have found that pure and TiOx-containing nanostructured carbon is modified under high flux UV exposure showing the onset of a metallic character near the Fermi level. We have studied the spectroscopic features, the spatial confinement, and the kinetics of this metallization process of the irradiated regions. This effect allows one to write metallic patterns in the TiOx-containing films with a submicrometric resolution and with a fast kinetic.

This paper reports a microfabrication technique viable for the production of microfluidic devices which can be reusable through disassembly and re-assembly routines using mechanical fastening configuration. A biocompatible water swollen poly (hydroxyethyl methacrylate) (PHEMA) hydrogel thin film of thickness ranging from 200 to 1000 µm is incorporated in a thermoplastic based multilayer system, as such its effectiveness of sealing is investigated through liquid leakage tests. In the test, pressurized air is injected in liquid filled microchannels machined on the hard polymeric component and sealed on one side by a compressed PHEMA layer. The critical pressure values of the fluid corresponding to the leakage at the materials' interface have been registered for different hydrogel strain values and multiple microchannels depth. A COMSOL simulation has also been implemented to simulate the mechanical behaviour of the hydrogel in the custom device settings for different packaging and critical fluid flow pressure values.

Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

Achieving the required control of dopant distribution and selectivity for nanostructured semiconducting building block is a key issue for a large variety of applications. A promising strategy is monolayer doping (MLD), which consists in the creation of a well-ordered monolayer of dopant-containing molecules bonded to the surface of the substrate. In this work, we synthesize a P δ-layer embedded in a SiO2 matrix by MLD. Using a multi-technique approach based on time of flight secondary ion mass spectrometry (ToF-SIMS) and Rutherford backscattering spectrometry (RBS) analyses, we characterize the tuning of P dose as a function of the processing time and temperature. We found the proper conditions for a full grafting of the molecules, reaching a maximal dose of 8.3 × 10(14) atoms/cm(2). Moreover, using 1D rate equation model, we model P diffusion in SiO2 after annealing and we extract a P diffusivity in SiO2 of 1.5 × 10(17) cm(2) s(-1).

Nanostructured cubic zirconia is a strategic material for biomedical applications since it combines superior structural and optical properties with a nanoscale morphology able to control cell adhesion and proliferation. We produced nanostructured cubic zirconia thin films at room temperature by supersonic cluster beam deposition of nanoparticles produced in the gas phase. Precise control of film roughness at the nanoscale is obtained by operating in a ballistic deposition regime. This allows one to study the influence of nanoroughness on cell adhesion, while keeping the surface chemistry constant. We evaluated cell adhesion on nanostructured zirconia with an osteoblast-like cell line using confocal laser scanning microscopy for detailed morphological and cytoskeleton studies. We demonstrated that the organization of cytoskeleton and focal adhesion formation can be controlled by varying the evolution of surface nanoroughness.

We present a compression based packaging technique which can be applied to reversibly seal hydrogel based materials' thin films and micro-fabricated thermoplastic components for hybrid materials stacking microfluidic cells-based chips design. A multilayer microdevice has been realized for liquid leakage tests at the thermoplastic/hydrogel interface nearby the fluidic circuits machined on the plastic layer; biocompatible Poly-hydroxyethylmethacrylate (PHEMA) hydrogel membranes with different thickness (Ranging from 100 to 200 μm) and micro-milled Polymethylmethacrylate components were chosen to realize the chip. By promoting continuous perfusion of the system pumping aqueous coloured dye solutions in the microchannels, the sealing between the two materials resulted guaranteed for tested flow rate values, ranging from 100nL/min to 10mL/min. Furthermore, to take the hydrogel into operation, a representative case study of a micro-bioreactor based on joint hybrid materials and employing PHEMA thin film as a cell culture substrate has been analyzed and modelled by mean of numerical simulation.

Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological features. The quantitative information, provided by this study about the relation between surface nanoscale morphology and bacterial adhesion points towards the rational design of implant surfaces that control or inhibit bacterial adhesion and biofilm formation.

The presence and stability of sp hybridized atoms in free carbon nanoparticles was investigated by NEXAFS spectroscopy. The experiments show that a predominant fraction of carbon atoms is found in linear sp-chains and that conversion into sp(2) structures proceeds already at low temperature and in the gas phase.

Background: Microneedle-mediated drug delivery is a promising method for transdermal delivery of insulin, incretin mimetics, and other protein-based pharmacologic agents for treatment of diabetes mellitus. One factor that has limited clinical application of conventional microneedle technology is the poor fracture behavior of microneedles that are created using conventional materials and methods. In this study polymer microneedles for transdermal delivery were created using a two-photon polymerization (2PP) microfabrication and subsequent polydimethylsiloxane (PDMS) micromolding process. Methods: Solid microneedle arrays, fabricated by means of 2PP, were used to create negative molds from PDMS. Using these molds microneedle arrays were subsequently prepared by molding eShell 200, a photo-reactive acrylate-based polymer that exhibits water and perspiration resistance. Results: The eShell 200 microneedle array demonstrated suitable compressive strength for use in transdermal drug delivery applications. Human epidermal keratinocyte viability on the eShell 200 polymer surfaces was similar to that on polystyrene control surfaces. In vitro studies demonstrated that eShell 200 microneedle arrays fabricated using the 2PP microfabrication and PDMS micromolding process technique successfully penetrated human stratum corneum and epidermis. Conclusions: Our results suggest that a 2PP microfabrication and subsequent PDMS micromolding process may be used to create microneedle structures with appropriate structural, mechanical, and biological properties for transdermal drug delivery of insulin and other protein-based pharmacologic agents for treatment of diabetes mellitus.

The high brilliance of the new generation of synchrotron radiation sources improves the grazing incidence x‐ray diffraction techniques and leads to great advances in the determination of crystal surface structures. The evaluation of the diffraction pattern intensity can be obtained in the distorted‐wave approximation introduced by Vineyard. In conditions of total reflection, typical penetration depths are about 50 A and only the atoms in the near‐surface layers interact with the electric field and produce the diffraction pattern. This model is the ground for a simulation code developed in order to calculate the diffracted peaks intensity of reconstructed and/or relaxed surfaces. An example of application, the Au (110) (1×2) reconstructed surface, is given. The intensity and the position of the diffraction peaks are determined for different values of the azimuthal angle and for different diffraction orders. The program takes into account the parameters of the beamline Advanced Line for Overlayer Interface and Surface Analysis (ALOISA) which will be available at the storage ring ELETTRA in Trieste.

Nowadays, there is a great interest in developing microdevices able to perform in-vitro cell assays for high throughput drug screening. In this work, we propose two modules that could be integrated in a single platform: a gold microelectrode array (MEA) for single-site cell transfection and two interdigitated electrodes (IDEs) arrays for the controlled localization of cells and the delivery of bio-chemical species. The modules have been already realized, separately tested and both have demonstrated their feasibility. The final aim is to perform single-site drug delivery in a microfluidic structure where different bio chemical species could be addressed to different cell groups in specific areas of the chip. In perspective, an high level of integration can be obtained by combining the two miniaturized approaches through microfabrication techniques, resulting in a portable and high throughput system for fast and efficient in-vitro drug screening.

International audience; We report the direct observation of solidlike ordering at room temperature of thin films of [Bmim][NTf2]ionic liquid on mica, amorphous silica, and oxidized Si(110). A statistical quantitative analysis of atomicforce microscopy topographies shows that on these surfaces [Bmim][NTf2] forms layered structures,characterized by a perpendicular structural periodicity of ∼0.6 nm. Remarkably, even the highest structures,up to 50 nm high, behave solidlike against the AFM probe. Conversely, on highly oriented pyrolitic graphitethe ionic liquid forms nanometer-sized, liquidlike domains. The results of this study are directly relevant forthose applications where ILs are employed in form of thin films supported on solid surfaces, such as inmicroelectromechanical or microelectronic devices. More generally, they suggest that at the liquid/solid interfacethe structural properties of ILs can be far more complex than those depicted so far, and prompt new fundamentalinvestigations of the forces that drive supported ILs through a liquidlike-to-solidlike transition.

The electrical properties of cluster-assembled nanostructured palladium oxide $({\text{ns-PdO}}_{x})$ thin films grown by supersonic cluster beam deposition have been characterized by means of a customized ac current-sensing atomic force microscope. Scanning impedance microscopy is shown to provide a deep picture of the electrical properties of thin nanostructured interfaces even in the case of very soft and poorly adherent films. In particular, the dielectric constant of ${\text{ns-PdO}}_{x}$ can be quantitatively determined as well as its $I\text{\ensuremath{-}}V$ characteristics. Moreover, the measurement of the tip-sample parasitic capacitance can be exploited to probe the overall mesoscale conductive character of thin films and to give a complementary and more precise view of the oxidation of ${\text{ns-PdO}}_{x}$ obtained by x-ray photoemission spectroscopy.

Amorphous carbon films with $sp\text{\ensuremath{-}}s{p}^{2}$ hybridization, produced by supersonic cluster beam deposition, shows the presence of both polyynic and cumulenic species [L. Ravagnan et al., Phys. Rev. Lett. 98, 216103 (2007)]. Here, we present an in situ Raman characterization of the low-frequency vibrational region $(400\char21{}800\text{ }{\text{cm}}^{\ensuremath{-}1})$ of $sp\text{\ensuremath{-}}s{p}^{2}$ films at different temperatures. We report the presence of two peaks at 450 and $720\text{ }{\text{cm}}^{\ensuremath{-}1}$. The lower frequency peak shows an evolution with the variation of the $sp$ content and it can be attributed, with the support of density functional theory simulations, to bending modes of $sp$ linear structures. The peak at $720\text{ }{\text{cm}}^{\ensuremath{-}1}$ does not vary with the $sp$ content and it can be attributed to a feature in the vibrational density of states activated by the disorder of the $s{p}^{2}$ phase.

Poly(amidoamine)s are biocompatible biodegradable polymers, which can be easily functionalized with a number of bioactive and biomimetic compounds. Co-polymerization of these polymers with 4-aminobutyl guanidine (agmatine) leads to an RGD mimicking structure. Hydrogels based on this structure showed an enhanced cell adhesion and could be chemically linked to a glass substrate to create a bioadhesive support for cell growth. Preliminary optimization and cell adhesion tests on Madin-Darby Canine Kidney cells were performed, both on functionalized and non-functionalized structures, with promising results.

Heating of grazing incidence mirror surfaces by absorbed soft X-rays from a synchrotron beamline has been studied numerically to evaluate resultant displacements of the thermally loaded surface. Subsequent ray-tracing analysis has provided the corresponding change in optical performances. This procedure has been applied in particular to a thermally loaded prefocussing ellipsoidal mirror to be used in a high-spectral-resolution soft-X-ray beamline in the U2 undulator beamline of ELETTRA, and ultrahigh brightness synchrotron radiation facility under construction in Trieste. Various cooling geometries have been investigated. A detailed analysis of the results indicates deterioration of imaging properties beyond the present fabrication tolerances only at extreme irradiation levels.

We report the production and characterization of a form of amorphous carbon with s p-s p(2) hybridization (atomic fraction of sp hybridized species > or =20%) where the predominant sp bonding appears to be (=C=C=)(n) cumulene. Vibrational and electronic properties have been studied by in situ Raman spectroscopy and electrical conductivity measurements. Cumulenic chains are substantially stable in high vacuum conditions for temperatures lower than 250 K and they influence the electrical transport properties of the s p-s p(2) carbon through a self-doping mechanism by pinning the Fermi level closer to one of the mobility gap edges. Upon heating above 250 K the cumulenic species decay to form graphitic nanodomains embedded in the s p(2) amorphous matrix thus reducing the activation energy of the material. This is the first example of a pure carbon system where the s p hybridization influences bulk properties.

Fullerene-like MoS2 and WS2 nanoparticles can be used as building blocks for the fabrication of fluid and solid lubricants. Metal dichalcogenide films have a very low friction coefficient in vacuum, therefore they have mostly been used as solid lubricants in space and vacuum applications. Unfortunately, their use is significantly hampered by the fact that in the presence of humidity, oxygen and moisture, the low-friction properties of these materials rapidly degrade due to oxidation. The use of closed-cage MoS2 and WS2 nanoparticles may eliminate this problem, although the fabrication of lubricant thin films starting from dichalcogenide nanoparticles is, to date, a difficult task. Here we demonstrate the use of supersonic cluster beam deposition for the coating of complex mechanical elements (angular contact ball bearings) with nanostructured MoS2 and WS2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications.

We present a multilayer microfluidic system having a KrF excimer laser micro-patterned thermo-responsive poly-(N-isopropyl)-acrylamide (PNIPAAm) based hydrogel layer integrated as a freestanding component that operates as a temperature-triggered cell isolation actuator for single cell assays applications. When the system is assembled, the size of the laser machined micro-through-hole (entrance diameter is 150 μm, while exit hole diameter varies from 10 to 80 μm) can be reversibly modulated as a consequence of the polymer volumetric phase transition induced by heating the device above the critical temperature of 32 °C; as a result of the polymer water loss, the shrinkage of the layer caused the hole to homogeneously shrink, thus reducing its original size to about 40% in the polymer collapsed state. This actuation mechanism was exploited to trap a cellular sample in the shrunken exit hole on the top of the hydrogel layer by applying a negative pressure across the film when the system is brought to 37 °C. Subsequently, the funneling of the trapped cell took place through the orifice when the polymer's natural relaxation at room temperature toward its initial state occurred; the functionality of the device was proved using optical microscopy to monitor MG63 cells as a model cell line during the funneling through the size-modulating structure.