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The microfabrication process of mushroom-like structures on Si[1 0 0] wafers is discussed. The mechanical characterization of the structures was performed using a nanoindenter and the compliance results are compared with a model based on standard bending theory. The proposed model suggests the existence of three different bending behavior zones: one of constant compliance over the silicon support, one that presents the expected cubic behavior with the applied load position far from the support, and one transition zone between the two. The model was used to perform experimental data fitting showing an excellent agreement with the observed behavior. [Copyright &y& Elsevier]

Dispersions of polymer and cerium acetate were deposited by electrospinning as nanofibers onto a metallic target, with the concentration of the precursor varied from 15% down to 3% (in weight). The different samples of deposited material were then transformed into CeO2 nanowires by thermal treatment at temperatures ranging from 350 to 950 °C. Raman Spectroscopy and X-Ray Diffraction data indicate a full conversion into cerium dioxide for all mass ratios without indicating other stoichiometries. Scanning Electron Microscopy shows the formation of nanowires, with diameters varying from (81 ± 5) nm to (200 ± 10) nm for cerium acetate concentrations ranging from 3%, 5%, 10%, and 15%. Transmission Electron Microscopy reveals that the nanowires are polycrystalline, and nanocrystal average sizes are compatible with the crystalline coherence length extracted from X-Ray Diffraction. The Thermal Treatment temperature does not seem to affect the nanowire average diameter; thus, this fabrication method's main control parameter for tailoring the CeO2 nanowire diameter by this fabrication method is the cerium acetate concentration within the deposition solution. [ABSTRACT FROM AUTHOR]

Abstract: Self-assembled nano-arrays have a potential application as solid-phase diagnostics in many biomedical devices. The easiness of its production is directly connected to manufacture cost reduction. In this work, we present self-assembled structures starting from spin coated thin films of carboxylated polystyrene (PSC) and xyloglucan (XG) mixtures on both mica and silicon substrates. AFM images showed PSC nanospheres on top of a homogeneous layer of XG, for both substrates. The average nanosphere diameter fluctuated for a constant speed and it was likely to be independent of the component proportions on the mixture within a range of 30–50% (v/v) PSC. It was also observed that the largest diameters were found at the center of the sample and the smallest at the border. The detected nanospheres were also more numerous at the border. This behavior presents a similarity to spin coated colloidal dispersions. We observed that the average nanosphere diameter on mica substrates was bigger than the nanosphere diameters obtained on top of silicon substrates, under the same conditions. This result seems to be possibly connected to different mixture–surface interactions. [Copyright &y& Elsevier]

Abstract: Thin polystyrene–polysaccharide films were deposited on mica by spin coating evaporating mixtures. Solutions of PS (polystyrene) in chloroform (15, 30 and 60mg/L) and XG (xyloglucan) in water (15mg/L) were prepared and mixed by stirring in different proportions. After evaporation by spin coating, a low order array of nanospheres was observed by AFM on top of a homogeneous layer, contingent on the proportion of the components in the original mixtures. A XG nanosphere array formed on top of a polystyrene layer was obtained from mixtures containing from 5 to 30% (v/v) of a 15mg/L XG solution and 95–70% (v/v) of a 15mg/L PS solution. XPS results showed that equal amounts of XG and PS were adsorbed on the mica substrate for 50% (v/v) XG as well as for 10% (v/v) XG mixtures. PS adsorption was not detected when the XG proportion was 90% (v/v). PS nanospheres were only obtained on top of the XG layer when the PS concentration was increased to four times the original solution. Furthermore, for a constant spin coating speed, the nanosphere diameter was found to be independent of the component proportion within the investigated range. We also found that the nanosphere diameter is correlated to the inverse square-root of the spin coating speed. [ABSTRACT FROM AUTHOR]

Degenerative diseases, such as osteoarthritis, osteoporosis and accidents can cause hip problems and injuries leading to a necessary hip prosthetic replacement. Acetabular and femoral prosthesis parts, consisting of special alloys of steel and titanium, are fixed to the bones using orthopedic cement based on poly(methyl methacrylate) (PMMA). With aim of improving implant material properties in terms of compatibility with the human body, were evaluated the bioactive responses of ISO 5832-9 steel and Ti6Al4V alloy coated with electrospun PMMA nanofibers. The electrospinning technique is widely used due to the possibility of easily producing fibers within nano or micrometric scale using a low cost, simple experimental apparatus that allows large-scale production. In this work the metallic substrates were submitted to surface pretreatments with sanding alone or in combination with acid etching. After deposition by electrospinning, the surfaces were characterized morphologically, chemically, and for roughness. PMMA fibers were obtained, with nanometric diameter, forming a uniform and homogeneous layer over both metal sample surfaces without appreciable differences in adhesion. The sanded surface, being a one-step process, was chosen for the next step. Fibroblasts were grown on the sample surfaces, for seven days, to determine biocompatibility. Electrospinning Induced Surface Activation (EISA) was used to incorporate hydroxyl radicals into the PMMA chain to produce hydroxylated PMMA, that was later redissolved and electrospun into nanofibers. Both samples (PMMA and PMMA-OH nanofibers) resulted in good cell adhesion properties. However, a denser cell monolayer was observed on the hydroxyl-terminated sample, indicating better cell-material interaction. Hydroxyl (OH) functionalized molecules can regulate cell behavior acting as a linker capable of reacting with proteins, thus accelerating cell growth, migration, differentiation, synthesis of extracellular matrix components, and tissue morphogenesis. By a simple two-step methodology it was possible to obtain electrospun hydroxyl functionalized bioactive PMMA nanofibers deposited on metallic implant samples with an increased cell response. • One step metal surface modification is adequate to nanofibers deposition. • Homogenously distributed PMMA nanofibers were produced by direct electrospinning. • PMMA nanofiber presented distribution homogeneity and good adhesion. • Hydroxylated PMMA nanofibers improved cell adhesion and proliferation. [ABSTRACT FROM AUTHOR]