Ammar Azioune

Adsorption of human serum albumin onto polypyrrole powder and polypyrrole-silica nanocomposites

Adsorption of human serum albumin (HSA) onto polypyrrole powder and polypyrrole-silica nanocomposite is investigated at pH 7.4 and RT using UV spectroscopy. the nanocomposite is more effective than the powder in adsorbing HSA (147 and 63 mg/g, respectively). XPS was used to detect characteristic features of the adsorbed HSA and to construct adsorption isotherms. These latter were in fair agreement with those obtained via UV. Polypyrrole-silica is adsorptive towards HSA at pH 7.4 by contrast with the quasi-zero adsorption previously obtained with the DNA adsorbate (Saoudi et al., J. Colloid Interface Sci. 1997).

Robust method for high-throughput surface patterning of deformable substrates.

We describe a simple and robust method for high-throughput surface patterning of deformable substrates such as silicone rubber films covered with a thin layer of protein and cell antifouling hydrogel (PLL-g-PEG). The irradiation with deep UV (<200 nm) of PLL-g-PEG-coated rubber substrates through a synthetic quartz photomask created micropatterns over a large area of the substrate. Incubation with proteins resulted in stable patterns with high feature resolution. RPE1 cells seeded on fibronectin patterns were constrained for days even after stretching. We also propose the crossbow feature as an interesting example allowing the stretching of normalized stress fibers.

Polymer dielectric treatment using ultraviolet-ozone: A photoelectron spectroscopy and ellipsometric porosimetry study

Ultraviolet-ozone (UV-O3) treatment of polyarylene, a semiconductor dielectric polymer, has been characterized using contact angle measurements, x-ray photoelectron spectroscopy, spectroscopic ellipsometry (SE), and ellipsometric porosimetry. Significant modification of the film surface composition is already observed after a short exposure time (30s). Longer treatment time leads to further increase in oxygen concentration and formation of an oxidized surface layer and densification of the film as evidenced by solvent adsorption data. Results obtained from SE indicate few changes in optical parameters, thickness, and refractive index (RI) of the film, up to 5min of UV-O3 treatment. Increasing the exposure time further leads to a substantial change in film thickness and an increase in RI. The same trend was observed for porous polyarylene but to a stronger extent. A dense layer at the porous polymer surface is only formed after 20min of treatment. Under these conditions, the optical properties of the mater...

Characterization of acid‐base properties of polymers and other materials: relevance to adhesion science and technology

This paper reviews the background to the theory of Lewis acid-base (AB) interactions in adhesion, adsorption, wetting and mixing of polymers and other materials (pigments, fillers, fibres, etc.). These specific materials interactions require the revision of old concepts (« polar » interactions) and the development of new analytical techniques and methodologies. Four of the most currently used techniques to characterize AB interactions are described: contact angle measurements, inverse gas chromatography, X-ray photoelectron spectroscopy, and atomic force microscopy.

X-ray photoemission spectroscopy and secondary-ion mass spectroscopy applied to the compositional study of pre-colonial pottery from Pantanal, Brazil

X-ray photoemission spectroscopy (XPS) and time-of-flight (TOF) secondary-ion mass spectroscopy (SIMS) have been applied to investigate potsherd samples from Pantanal, Brazil. One of the potsherds presented burnt bone as an additive, which was characterized by XPS as carbonate hydroxyapatite. For shell-tempered ceramics the phase present in shells after firing was identified by X-ray diffraction. TOF-SIMS was used to study the distribution of quartz as temper in one of the sherds. XPS was also applied to the characterization of the finishing external layer of the ceramic vessels. In this case, based on the Fe 2p spectra of the sherds interior and outermost layers, it was possible to prove that their difference in coloration is due to black heart formation. Hierarchical clustering analysis and principal component analysis of the XPS elemental data enabled the potsherds to be classified with respect to their clay composition.