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Macropatterned and micropatterned gold/silicon dioxide/titanium tungsten (Au/SiO2/TiW) substrates were orthogonally functionalized: three different molecules (monovalent silane, thiol, and phosphonic acid) were used to specifically form organolayers on Au, SiO2, or TiW areas of patterned substrates. The orthogonality of the functionalization (i.e., selective grafting of thiol on Au, phosphonic acid on TiW, and silane on SiO2) was assessed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements. These results are especially promising for the selective anchoring of targets (e.g., biomolecules, nanoparticles, nanowires, nanotubes, or other nano-objects) onto patterned zones of multimaterial substrates, such as nanosensors or other nanodevices.

In previous work, textiles for the food processing industry were coated with an original deposition technique based on a combination of plasma-enhanced chemical vapor deposition and physical vapor deposition to obtain ~ 10 nm size silver clusters incorporated into a SiOCH matrix (Ag-SiOCH coating). However, the stability of the coating in end-use conditions (abrasion during washing cycles and/or oxidation) is questionable and this work is specifically devoted to study the effect on antimicrobial activity of Ag-SiOCH coatings after deposition of high porosity and low density protective layers. The Ag-SiOCH coating was thus covered with encapsulation layers (either hydrophobic SiOCH or hydrophilic AlxOy). The surface and bulk characterisation results of the multilayer coatings using X-ray Photoelectron Spectroscopy (XPS), Dynamic Secondary Ion Mass Spectrometry (DSIMS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) were used to study the composition of the coating and quantify the presence of the antimicrobial agent (Ag) at the surface and inside of the coating. Antibacterial tests indicated that antimicrobial activity of coated textiles was maintained. However, the antimicrobial activity was not directly correlated with the Ag content detected at the top surface or with the distance from the top surface to the part of the coating containing a significant amount of silver (as detected by XPS) and diffusion mechanisms during antibacterial tests could play a significant role. In particular, the hydrophilic character of AlxOy deposit likely allowed a better availability of the antimicrobial agent (Ag) but it was also observed for SiOCH hydrophobic deposits.

International audience; Understanding the structural and electronic factors governing the efficiency of dye-sensitized NiO photocathodes is essential to optimizing solar fuel production in photoelectrochemical cells (PECs). For this purpose, three different ruthenium dyes, bearing either two or four methylphosphonate anchoring groups and either a bipyridine or a dipyridophenazine (dppz) ancillary ligand, were synthesized and grafted onto NiO films. These, photoelectrodes were fully characterized by XPS, ToF-SIMS, and UV-vis absorption, time-resolved emission, and femtosecond transient absorption spectroscopies. Increasing the number of anchoring groups from two to four proved beneficial for the grafting efficiency. No significant modification of the electronic properties compared to the parent photosensitizer was observed, in accordance with the nonconjugated nature of the grafted linker. The photoelectrochemical activity of the dye-sensitized NiO electrodes was assessed in fully aqueous medium in the presence of an irreversible electron acceptor, and photocurrents reaching 190 mu A.cm(-2) were recorded. The transient absorption study revealed the presence of two charge recombination pathways for each of the sensitizers and evidenced a stabilized charge separated state in the dppz derivative, supporting its superior photoelectrochemical activity.

International audience; The aim of the this work was to study feasibility of titanium dioxide thin films prepared by atomic layer deposition (ALD) technique on aluminum foam substrates for photocatalysis and compare performance of thin films with commercially available AEROXIDE® TiO2. Formic acid and phenol photocatalytic decomposition was monitored using high-pressure liquid chromatography (HPLC). The morphology and thickness of TiO2 films were characterized by scanning electron microscopy (SEM) and their structure was determined by X-ray diffraction (XRD). Surface of the thin films was characterized with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The amount of TiO2 deposited on aluminum foam was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). It was observed that initial rates of formic acid and phenol degradation were 0.007 and 0.001 mmol L−1 min−1, respectively. The apparent quantum yields for formic acid using immobilized and reference TiO2 powder (AEROXIDE® TiO2 P25, Evonik) were 2.2 and 2.7%, correspondingly. While for phenol apparent quantum yield was equal to 0.4% when TiO2 thin film was used and 0.7% in the case of reference powder. A decrease of the photocatalytic activity of TiO2 films deposited on aluminum foam was observed after the first cycle for both model compounds. It was suggested from this study that suppression of activity occurs due to detachment of TiO2 from the surface of thin film.

International audience; Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a high performance tool for molecular depth profiling of polymer films, in particular when they are structured in microphases. However, a major issue is the degradation of polymer materials under ion irradiation in reactions such as cross-linking, chain breaking, or reorganization processes of polymers which have been demonstrated for materials such as polystyrene (PS) and poly(methyl methacrylate) (PMMA). This work aims at comparing ToF-SIMS molecular depth profiling of structured polymers (polystyrene (PS)-b-polymethyl methacrylate (PMMA) block copolymers (BCP)) using either ultralow energy cesium or the more recently introduced C60(++) (under NO dosing and with sample cooling) and argon cluster ion beams (using Ar-1500(+) ions at 5 keV). The latter improved the quality of the depth profiles, especially the argon cluster ion beam, as it is characterized by a greater homogeneity for the sputter yields of PS and PMMA. No significant artifacts were observed, and this was confirmed by the comparison of depth profiles obtained from films with variable thickness, annealing time, and morphology (cylindrical blocks vs spherical blocks). Comparison to a theoretical model (hexagonal centered pattern) ensured that the ToF-SIMS depth profiles described the real morphology and may thus be a relevant characterization tool to verify the morphology of the films as a function of the deposition parameters

Chemical modifications of cellulose fibers as pretreatment for cellulose nanofibrils (CNF) production have been investigated to improve the production process and the quality of obtained cellulosic nanomaterial. In this study, phosphorylation of cellulose fibers was done in anticipation of a future nanofibrillation. Different phosphate salts, namely NH4H2PO4, (NH4)(2)HPO4, Na2HPO4, NaH2PO4 and LiH2PO4 with different constants of solubility (Ks) were used to increase the efficiency of the modification. Phosphorylated cellulose pulps were analyzed using elemental analysis, solid-state C-13 and P-31 NMR, or conductimetric titration method. No effect of Ks was observed whereas a counterion effect was pointed out. The study also reported the effect of pH, cellulose consistency, temperature and urea content in phosphorylation efficiency. Finally, chemical functionalization and penetration of phosphorylation reagents in the cellulose fibers were evaluated using XPS, SEM-EDX, ToF-SIMS and solid-state NMR.

Polymer/metal nanocomposites films with different morphologies have been prepared from polyetherimide and palladium acetate with Pd amount ranging from 0 to 15 wt%. In a first step, hybrid precursor films have been obtained from polymer/metal complex solutions and the metal nanoparticles have been then generated within the PEI matrix by annealing the precursor film under different conditions. The membrane nanostructuration process and the final membrane morphology have been discussed as a function of the metal precursor amount and annealing conditions. The gas transport properties of the membranes have been analysed for CO 2 , He and H 2 . Specific interactions between hydrogen and the Pd based nanoparticles have been evidenced and the gas transport mechanisms have been discussed as a function of the gas nature, the nanoparticles structure and the nanoparticles location within the membrane.

TiO2:polymer bulk-heterojunctions (BHJ) have been elaborated from hydrolysis–condensation reactions of a TiO2 precursor in contact to the surrounding air humidity in a polymer thin film. A new precursor: tetrakis(9H-carbazole-9-yl-ethyl-oxy) titanium [Ti(OeCarb)4], has been synthesized as a TiO2 precursor to form a blend with Poly(N-vinylcarbazole) (PVK) which is the archetype of non-conjugated photoconducting polymer with strong electron-donor properties. This new precursor is expected to enhance the materials miscibility because of the chemical structure of the ligand close to the PVK repetitive unit and to inhibit premature hydrolysis by a strong steric hindrance. Commercial titanium isopropoxide [Ti(iOPr)4] was used as a reference to study the influence of the chemical structure of the precursor on BHJ properties. Photoluminescence studies have shown charge transfer enhancement when Ti(OeCarb)4 is used. In order to understand this ligand effect, photoluminescence (PL) responses were correlated with surface chemical composition (XPS) and topography (AFM) of thin films. Results have shown that Ti(OeCarb)4 allows a better miscibility between TiO2 and PVK. The lower reactivity of Ti(OeCarb)4 to hydrolysis and its chemical structure close to the repetitive unit structure of the polymer are believed to play a main role in the BHJ property improvement.

A bioflocculant TJ-F1 with high flocculating activity, produced by strain TJ-1 from a mixed activated sludge, was investigated with regard to its production and characterization. By 16S rDNA sequence and biochemical and physiological characteristics, strain TJ-1 was identified as Proteus mirabilis. The most preferred carbon source, nitrogen source and C/N ratio (w/w) for strain TJ-1 to produce the bioflocculant were found to be glucose, peptone and 10, respectively. TJ-F1 production could be greatly stimulated by cations Ca(2+), Mg(2+) and Fe(3+). The optimal conditions for TJ-F1 production were inoculum size 2 per thousand (v/v), initial pH 7.0, culture temperature 25 degrees C, and shaking speed 130r/min, under which the flocculating activity of the bioflocculant reached 93.13%. About 1.33 g of the purified bioflocculant, whose molecular weight (MW) was 1.2 x 10(5) Da, could be recovered from 1.0 l of fermentation broth. Chemical analysis of bioflocculant TJ-F1 indicated that it contained protein (30.9%, w/w) and acid polysaccharide (63.1%, w/w), including neutral sugar, glucuronic acid and amino sugar as the principal constituents in the relative weight proportions of 8.2:5.3:1. Scanning electron microscopy (SEM) image of the purified solid-state TJ-F1 showed that it had a crystal-linear structure. Spectroscopic analysis of the bioflocculant by Fourier-transform infrared (FTIR) spectrometry indicated the presence of carboxyl, hydroxyl and amino groups preferred for the flocculation process.

We report a new approach based on DNA hybridization for detecting HBV virus using non-faradic electrochemical impedance spectroscopy. DNA probes modified with biotin in 5′ position were immobilized on streptavidin modified magnetic nanoparticles by biotin–streptavidin interaction. A layer of functionalized nanoparticles was directly immobilized on bare gold electrode using a magnet. Before detection atomic force microscopy was used to visualize the layer of magnetic nanoparticles and cyclic voltammetry permitted to characterize DNA probe immobilization. The hybridization reactions with specific complementary DNA target and no complementary target were investigated by non-faradic impedance spectroscopy. Results show the good immobilization of the DNA probes and the hybridization with different concentrations of complementary DNA. Non-faradic impedance spectroscopy allows to detect 50 pmol of HBV DNA and 160 pmol of HIV DNA on sample of 20 μL. Saturations were reached for the same concentration 12.65 nmol/mL for a same quantity of immobilized DNA probes.

The necessity to adapt sensors based on electrochemical techniques for high throughput analysis control increases the interest to develop new analytical systems able to perform measurements under buffer flow. In this report we explored the possibility of employing a new system to make impedimetric measurements to detect the interaction between proteins and small molecules. The well-known biotin–streptavidin interaction was adopted to evaluate the proposed assembly. This system allows us to perform experiments under flow. Magnetic beads functionalized with streptavidin were used and first characterized using AFM and FTIR. Non-faradic impedance spectroscopy allowed the detection of the biotin–streptavidin interaction. Using our new system and under a flow of PBS buffer, 5 10− 5 M of biotin was detected with a stable signal.

A hexavalent chromium-sensitive EMIS sensor (electrolyte membrane insulator semiconductor sensor) is prepared by deposition of a tributylphosphate (TBP) ionophore-containing siloprene membrane on a Si/SiO2/Si3N4 structure. The developed EMIS sensor was studied by means of impedance spectroscopy, capacitance–voltage, X-ray photoelectron spectrometry and FT-IR spectroscopy. From the flat-band shift of the EMIS structure, the nersntian response to the anionic species Cr2O7− was demonstrated. The linear range of detection is 10− 4 M to 10− 1 M and the detection limit is 10− 5 M. Sulfate and chloride anions are shown not to be interfering whereas carbonate ions present a pKpot equal to 0.19.

Cast-hybrid films composed of polyvinyl alcohol (PVA) and silver nitrate were treated according to three different ways, thermal annealing, UV-irradiation, and chemical reduction by a borohydride solution, to obtain PVA/silver nanocomposite films. The nanostructuration process was studied as a function of the treatment conditions, and discussed as a function of the mobility state of the polymer chains in the nanocomposite matrix during treatment. A homogeneous dispersion of crystalline silver nanoparticles was obtained by thermal annealing above Tg and below Tm and UV-lamp irradiation below Tg. For these two treatments, the major processing parameters were the annealing temperature and time and the UV-exposure time, respectively. For low-conversion rate in Ag(0), the films evolved upon ageing at room temperature. Totally different morphology and Ag(0) conversion were achieved by chemical reduction in a borohydride solution. All the silver ions were reduced into Ag(0), and crystalline silver nanoparticles layers parallel to the film surface were observed after the treatment. This morphology was related to the high-swollen state of the polymer matrix during treatment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2062–2071, 2008

A study on the synthesis of La 1− x Ag x MnO 3+ δ ( x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure ( T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h). Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La 0.8 Ag 0.2 MnO 3+ δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts.

International audience; Single-step orthogonal chemical functionalization procedures have been developed with patterned gold on silica surfaces. Different combinations of a silane and a thiol were simultaneously deposited on a gold/silica heterogeneous substrate. The orthogonality of the functionalization (i.e., selective grafting of the thiol on the gold areas and the silane on the silica) was demonstrated by X-ray photoelectron spectroscopy (XPS) as well as time-of-flight secondary ion mass spectrometry (ToF-SIMS) mapping. The orthogonal functionalization was used to immobilize proteins onto gold nanostructures on a silica substrate, as demonstrated by atomic force microscopy (AFM). These results are especially promising in the development of future biosensors where the selective anchoring of target molecules onto nanostructured transducers (e.g., nanoplasmonic biosensors) is a major challenge

SSCI-VIDE+CARE+DAG:CGU:IBE; International audience; Stability and photocatalytic efficiency of hybrid composite films obtained by efficient dispersion of anatase TiO2 nanoparticles in various hybrid silica matrices are investigated in order to address the structure/reactivity relationship. The photocatalytic activity is systematically monitored as a function of the chemical composition of the matrix at the molecular level, and thus the final structure of the material. The partial elimination of the organic groups brings by the organosilane precursors under UV exposure was followed by HPLC and by surface analysis (XPS, contact angle). The impact of the alkoxysilane structure on the final structure of the matrix is evaluated. In the same way, the impact of thermal and photonic pretreatments on the coating photocatalytic activity is evaluated using formic acid as model pollutant. Finally, the role of the remaining organic groups in the silica network on the structure modification and on the photocatalytic activity is investigated by varying their nature and ratio. Depolluting and self-cleaning activities of optimized coatings are studied by degrading formic acid and methylene blue in different conditions of pollutant concentration and photon flux. We interestingly show that in all cases, the presence of the organic groups in the matrix induces an increase in the photocatalytic efficiency. Finally, efficient photocatalytic flexible films are prepared and show promising photocatalytic degradation mechanism under low UV excitation, comparable to solar UV irradiation.Highlights• Composite coatings made of commercial TiO2 inserted into a hybrid silica matrix.• UV pretreatment is necessary to improve the photocatalytic efficiency.• Thermal treatment is harmful for the photocatalytic efficiency.• The coating stability is followed by HPLC and by surface analysis (XPS, contact angle).• Presence of the silica organic groups is necessary to increase the coating efficiency.

The authors also would like to thank Prof. T. Filleter from the NanoMechanics and Materials Laboratory, University of Toronto, for his review of the paper and his comments during the redaction process.; International audience; MoS2 is a well-known lubricant for vacuum application. However, the role of contamination in achieving low friction and long wear life in industrial applications remains unclear as the literature presents some contradictions. A former study performed in ultrahigh vacuum showed that in a sliding macro contact, the origin of low friction was primarily due to the formation of a 3rd body layer, its trapping and its ability to flow plastically inside the contact. The study showed a homogenisation of the chemical elemental composition of the material and the internal coating contaminants throughout the contact and the 3rd body. To study that homogenisation and to verify if a chemical rearrangement occurred at a molecular level under friction, Time-of-Flight Secondary Ion Mass Spectroscopy analyses are performed. Firstly, they show that the MoS2 coating made by Physical Vapour Deposition is not a "MoS2" but is a complex MoxSyOz structure. Secondly, they show that a chemical rearrangement of the material with the internal contaminants effectively occurs in ultrahigh vacuum and leads to the formation of a unique MoSxOy phase. Such a phase shows the beneficial role of reasonable contamination on the tribological behaviour.

The tin-free electroless metallization process developed in our laboratory consists in attaching the Pd(+ 2)-based catalyst on surfaces which were previously grafted with nitrogen-bearing groups. The so-functionalized surfaces lead to the formation of true covalent bonds between palladium and nitrogen-based species. In this work, the different steps of the process are studied, namely: (i) the grafting of nitrogen-bearing groups on an insulating surface by various processes already used in our laboratory, (ii) the seeding of the surface with Pd(+ 2) species, (iii) the reduction of Pd(+ 2) to Pd(0) by different routes (this step is needed due to the use of industrial plating baths which contain strong stabilizers that prevent or delay plating), (iv) the Ni metallization using low- and high-phosphorus plating baths. Phosphorus which originates from the plating bath reducer is partly incorporated in the Ni films and creates some stresses. Adhesion of the resulting films is evaluated by the Scotch® tape test. The main parameters responsible for adhesion and governing the characteristics of the Ni film/substrate interface are: the nature of the substrate, the Pd(+ 2) reduction route and the phosphorus content of the Ni plating bath. All these parameters influence the amount of stresses generated both at the metal/substrate interface and within the film.

Electroless plating of nickel (or copper) was carried out on glass (or silicon) substrates that were previously surface modified by using plasma-polymerization and grafting processes, and then activated by immersion in a simple acidic PdCl2 solution. Three pretreatments based on the deposition of plasma-polymerized thin films (PACVD process) on O2 plasma-cleaned substrates were investigated. They include film deposition of (1) amorphous hydrogenated carbon (a-C:H) grown from CH4, whose surface is subsequently plasma-functionalized in NH3 or N2; (2) amorphous hydrogenated carbon nitride (a-CNx:H) grown from CH4/NH3 or CH4/N2 mixtures; and (3) amorphous hydrogenated carbon nitride grown from volatile organic precursors (allylamine, acetonitrile). In the three cases, X-ray photoelectron spectroscopy (XPS) results show that chemisorption of the catalyst occurs on the nitrogen-containing functionalities created by plasma polymerization and grafting and thus that the electroless deposition is possible. Differen...

International audience; COOH-terminated self-assembled monolayers (SAMs) are widely used in biosensor technology to bind different amine-containing biomolecules. A covalent amide bond, however, can be achieved only if the carboxylic acids are activated. This activation process usually consists of forming an N-hydroxysuccinimidyl ester (NHS-ester) by consecutively reacting carboxylic acids with a carbodiimide and NHS. Though many papers report using this method,(1-8) the experimental conditions vary greatly between them and chemical characterization at this stage is often omitted. Evidence of an efficient activation is therefore rarely shown. Furthermore, recent publications(9-11) have highlighted the complexity of this process, with the possible formation of different byproducts. In this paper, we have conducted a study on NHS activation under different conditions with chemical characterization by polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Our results indicate that the nature of the solvent and carbodiimide and the reactant concentrations play crucial roles in activation kinetics and efficiency.

The potential of surface glycoengineering for biomaterials and biosensors originates from the importance of carbohydrate–protein interactions in biological systems. The strategy employed here utilises carbene generated by illumination of diazirine to achieve covalent bonding of carbohydrates. Here, we describe the synthesis of an aryl diazirine containing a disaccharide (lactose). Surface analysis techniques [X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrate its successful surface immobilisation on polystyrene (PS). Results are compared to those previously obtained with an aryl diazirine containing a monosaccharide (galactose). The biological activity of galactose- or lactose-modified PS samples is studied using rat hepatocytes, Allo A lectin and solid-phase semi-synthesis with α-2,6-sialyltransferase. Allo A shows some binding to galactose-modified PS but none to lactose-modified surfaces. Similar results are obtained with rat hepatocytes. In contrast, sialylation of lactose-modified PS is achieved but not with galactose-modified surfaces. The different responses indicate that the biological activity depends not only on the carbohydrate per se but also on the structure and length of the spacer.

Time-of-flight Secondary Ion Mass Spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS) are used to characterize a newly synthesized glycosylated photoactivatable reagent designed for surface glycoengineering. The immobilization on diamond surfaces of the glycoaryldiazirine reagent lactose aryl diazirine (5-carboxamidopentyl-N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl-β-D-galactopyranosyl]-(1->4)-1-thio-β-D-glucopyranoside) is compared to a previously studied monoglycosylated photoactivatable reagent (MAD-Gal). The XPS atomic constituents and chemical shifts, as well as ToF-SIMS specific characteristic fragments and molecular peaks of the new photoimmobilized molecule are recorded. Spectral differences are identified in XPS C 1s spectra and in the high mass range of positive ion ToF-SIMS spectra for the surface immobilized disaccharide. The ToF-SIMS characteristic high-mass ions involve both cationization with Na+ and loss of the diazirine function. The results can be related to differences observed in biological assays with each of the surface immobilized saccharides. Copyright © 2001 John Wiley & Sons, Ltd.

Thin titanium hydride (TiHy) films, covered by ultrathin gold layers, have been compared with the corresponding titanium films after analysis using a combination of time-of-flight SIMS (ToF-SIMS), XPS and AES. The TiHy layers were prepared under UHV conditions by precisely controlled hydrogen sorption at 298 K on Ti film evaporated onto a glass substrate. Both Ti and TiHy films were then covered in situ by a nanoscale Au layer. Analyses were performed in separate systems after long-term exposure of the films to air. The thin gold layers covering the Ti and TiHy surfaces prevent any extensive air interaction with both films, allowing characterization of the bulk Ti and TiHy layers ex situ, even after a long-term application in air. The chemical nature of the TiHy layers has been analysed after sputtering of the Au top layer. The high-mass-resolution positive-ion ToF-SIMS spectra disclosed only one peak at mass 49 (49Ti+) for the Ti and two peaks at mass 49 (49Ti+ and 48TiH+) for the TiHy film, reflecting a difference in hydrogen concentration. Analysis of the features of the Ti Auger spectra during the sputter profile measurements allows the TiHy to be distinguished and characterized in the bulk region of the Au/TiHy layer. Besides TiHy, TiO and TiOH were detected by XPS to be the main chemical compounds in the interface region of the Au/TiHy film.

The surface chemical characterization of melamine–formaldehyde (MF) resins by x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) is examined in this study. Melamine–formaldehyde resins with different molar ratios of formaldehyde to melamine are synthesized and thermally cured. From XPS measurements, quantitative information is obtained and atomic chemical concentrations show the effect of the molar ratio for the freeze-dried resins. However, the thermally cured resins display a rather similar surface elemental composition. Moreover, because the binding energy values of the main N–C–N and N–C–O groups are too close, XPS does not help to identify changes in chemical structure after curing. The main ToF-SIMS negative and positive mass fragments of the MF resins are identified. Principal component analysis (PCA) is shown to be useful to determine and explain the main differences between all of the ToF-SIMS spectra. It allows us to distinguish the effect of the bulk chemical composition on the respective surface compositions of not only the uncured but also the cured MF resins. Moreover, extended interpretation leads to the identification of peaks characteristic of methylol groups and methylene ether bridges, but their absolute quantification is not straightforward. However, this result indicates that surface analysis helps to characterize the poorly defined chemical structure of MF resins. This is important for understanding the influence of surface chemistry on macroscopic surface properties such as chemical durability under exterior exposure. Copyright © 2000 John Wiley & Sons, Ltd.

We report a new approach for immunoassays based on magnetite nanoparticles for Escherichia coli (E. coli) detection using conductometric measurements. Biotinylated antibodies, anti-E. coli, were immobilized on streptavidin modified magnetite nanoparticles by biotin–streptavidin interaction. A layer of functionalized nanoparticles were directly immobilized on the conductometric electrode using glutaraldehyde cross-linking.The specific test with E. coli cells and the non specific test using Staphylococcus epidermidis (S. epidermidis) were investigated by conductometric measurements. Results show a good response as a function of antigen additions. The detection of 1 CFU/ml of E. coli induces a conductivity variation of 35 μS. The negative test shows good selectivity using the conductometric immunosensor. Conductometric measurements allow to detect 500 CFU/l. Keywords: E. coli, Antigen–antibody interaction, Conductometric immunobiosensor, Magnetite nanoparticles, Atomic force microscopy

Teflon AF, an amorphous copolymer of polytetrafluoroethylene (PTFE) with 2,2-bis(triflouromethyl)-4,5-difluoro-1, 3-dioxole, has been receiving widespread attention in the opto-electronics industries and elsewhere for its superior optical and dielectric properties. The objective of the present study was to investigate surface parameters that may be required for the application of thin films of Teflon AF in the fields of biomaterials and bioelectronics. Using standard microelectronics procedures, micro-patterned thin films of Teflon-AF were fabricated, and their surface properties monitored and optimized with the aid of highly surface sensitive spectrometric techniques. Finally, their capability to inhibit or bio-pattern cell adhesion was tested with various neural cell lines.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS) are used to characterize the grafting of the reagent N-(m-(3-(trifluoromethyl)diazirine-3-yl)phenyl)-4-maleimido-butyramide (MAD) to various substrates: silicon, silicon nitride and diamond. MAD carries a maleimide function for thermochemical modification of thiolated molecules and a diazirine function that is lost during light activation (350 nm light). Photoactivation leads to carbene-mediated grafting to solid supports. X-ray photoelectron spectroscopy atomic constituents and chemical shifts, as well as ToF-SIMS molecular peaks and characteristic fragments of the photoimmobilized molecule, are identified. Extended interpretation of surface analysis data suggests that diamond is the substrate with the highest MAD grafting efficiency and that the formation of C-O bonds upon diazirine photoactivation is involved. The difference in grafting extent for the three substrates leads to the conclusion that other reaction sites could be involved but they are not identified. © 1998 John Wiley & Sons, Ltd.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS) are used to characterize a newly synthesized glycosylated photoactivatable reagent designed for surface glycoengineering. The glycoaryldiazirine reagent MAD-Gal (N-[m-(3-(trifluoromethyl)diazirine-3-yl)phenyl]-4-(-3-thio(-1-D- galactopyrannosyl)-maleimidyl)butyramide) is immobilized with 350 nm light on diamond surfaces. The XPS atomic constituents and chemical shifts, as well as ToF-SIMS-specific characteristic fragments of the photoimmobilized molecule, are identified. The grafting on oxygen-containing sites previously observed for N-(m-(3-(trifluoromethyl)diazirine-3-yl)phenyl)-4-maleimido-butyramide (MAD) is confirmed. The difference in grafting efficiency for fresh and aged substrates indicates that other still unidentified reaction sites could be involved. The ToF-SIMS imaging is used to exhibit the ability to pattern the surface with the glycosylated aryldiazirine. © 1998 John Wiley & Sons, Ltd.

International audience; The use of polymer materials in industry for product packaging is increasing. The presence of additives in the polymer matrix enables the modification or improvement of the properties and performance of the polymer, but these industries are concerned regarding the extractability of these additives. The quantification of these additives is particularly challenging because of the presence of these substances as contaminants in all the analytical equipment and the diversity of their physicochemical properties. In this context, a multi-residue analytical method was developed for the trace analysis of the twenty main additives (and their degradation products) authorized in plastic products such as pharmaceutical packaging (e.g., antioxidants, release agents, and light absorbers). This analytical method consisted of a solid phase extraction (SPE) followed by an analysis using ultra-high performance liquid chromatography coupled to a tandem mass spectrometer (UHPLC-MS/MS). A comparison of two ionization interfaces and the optimization of the extraction procedure were discussed. The influence of the quality of the solvent type (distilled versus not distilled) and the nature of the SPE cartridges (Polypropylene versus Teflon®) were demonstrated. The optimized method exhibited a quantification limit lower than 20 ng mL−1 and recoveries between 70 % and 120 % for all compounds. Finally, the method was validated according to the ICH directive and was subsequently applied to the extraction of polymers under different pH conditions and storage temperatures. To the best of our knowledge, this study presents the first methodology allowing the simultaneous quantification of 24 additives at low ng mL−1.

SSCI-VIDE+CARE+DAG:IBE:CGU; International audience; Photocatalytic porous coatings (micro-, meso- and macroporous) are obtained by the dispersion of TiO2 nanoparticles in sol–gel hybrid matrices. The sol–gel silica matrix is used as a binder stabilizing the nanoparticle dispersion and as a protective layer for the organic substrates. Organic groups are introduced into the matrix to induce the film flexibility and a part of them is used to create the final microstructure allowing remarkable improvement of the photocatalytic properties. The film structure and UV stability are fully characterized. The photocatalytic activity is evaluated through a test with formic acid. Flexible efficient photoactive composites are obtained showing important capabilities for depollution (water and air) and self-cleaning applications.

Instituto de Fsica de S¼o Carlos, Universidade de S¼o Paulo, Av. Trabalhador S¼o-carlense 400, S¼o Carlos, SP, postcode 369,13560-970, Brazil*e-mail: gdebora@ifsc.usp.brReceived: October 17, 2012Accepted: December 4, 2012Published online: February 22, 2013AbstractThe process for obtaining polypyrrole-2-carboxylic acid (PPY-2-COOH) films in acetonitrile was investigated usingcyclic voltammetry, electrochemical quartz crystal microgravimetry (EQCM), and infrared spectroscopy (FTIR).Different potential ranges were applied during cyclic voltammetry experiments with the aim of obtaining films with-out and with the presence of controlled amounts of water added in acetonitrile. The FTIR spectra of the films haveevidenced that cations and anions from the electrolyte solution were incorporated into the PPY-2-COOH structure,with a preferential adsorption of cations. After chemically immobilizing polyphenoloxidase (tyrosinase, PPO), PPY-2-COOH/PPO films were build for amperometric detection of catechol, establishing a linear limit of concentrationsranging from 5.010

International audience; Oligonucleotide solid-phase synthesis is now possible on nano-sized particles, thanks to the use of controlled pore glass-nanoparticle assemblies. We succeeded in anchoring silica nanoparticles (NPs) inside the pores of micrometric glass via a reversible covalent binding. The pore diameter must be at least six times the diameter of the nanoparticle in order to maintain efficient synthesis of oligonucleotides in the synthesizer. We demonstrated that the pores protect NP anchoring during DNA synthesis without decreasing the coupling rate of the phosphoramidite synthons. This bottom-up strategy for NP functionalization with DNA results in unprecedented DNA loading efficiency. We also confirmed that the DNA synthesized on the nanoparticle surface was accessible for hybridization with its complementary DNA strand.

This work presents a new sensor for ammonium determination based on interdigitated conductometric thin-film planar electrodes. It was fabricated by including nonactin in a plasticised poly(vinyl chloride) membrane deposited on the sensitive area of the transducer. The effects of pH, buffer concentration, the interferences of Na+, K+ and Ca2+ ions, the effect of ionic strength and of temperature were investigated. The linear working range and sensitivity of the biosensor were also determined. The sensitivity of the ammonium detection was around 6.2 S M-1 [image omitted] and the detection limit was 2 10-5 M. The biosensor exhibits the advantages of a simple fabrication procedure, good sensor-to-sensor reproducibility, wide dynamic range and good storage stability (12 weeks).

International audience; The chemical reactivity of the ligand initially coordinated on the TiO2 precursor plays a decisive role in the morphology of TiO2:poly(N-vinylcarbazole) (PVK) thin film elaborated by in situ generation of the inorganic phase in the polymer matrix. The final aim of this study is to prepare a new nanocomposite TiO2:poly(N-vinylcarbazole) (PVK) thin film from hydrolysis-condensation of titanium alkoxide in polymer thin film. In this context, we synthesized a new TiO2 precursor, the tetrakis (9H-carbazole-9-yl-ethyl-oxy) [Ti(OeCarb)4], bearing ligands close to the repetitive unit structure of the PVK to improve the interaction between both materials. In this study, the synthesis and reactivity to hydrolysis of Ti(OeCarb)4 is presented. Ti(OeCarb)4 was elaborated from alcoholysis reaction between titanium isopropoxide [Ti(iOPr)4] and 9H-carbazole-9-ethanol (ECOH) and identified by 1H and 13C NMR spectroscopy. The reactivity to hydrolysis-oxolation of Ti(OeCarb)4 was evaluated first in aqueous media by in situ 1H NMR spectroscopy analysis. Moreover, reactivity of Ti(OeCarb)4 to surrounding humidity was evaluated in thin film by X-ray photoelectron spectroscopy (XPS). Results show that steric hindrance of 9H-carbazole-9-yl-ethyl-oxide ligands do not influence the hydrolysis-condensation process in aqueous media in our experimental conditions when compared to [Ti(iOPr)4] but decrease the reactivity when the precursor is simply exposed to air humidity.

Polyethylene Terephthalate 12-mu-m thick films (Mylar(R)) have been subjected to an industrial gaseous fluorination treatment. The chemical surface modifications of the treated films have been studied with the aid of various surface sensitive techniques (ISS, SSIMS and XPS); thanks to the complementarity of these techniques, the chemical reaction scheme at the surface is emphasized. The ISS technique provides the elemental chemical composition of the first topmost monolayer. In the case of polymers, it is thought that the low carbon sensitivity of ISS is due to the shielding of the carbon atoms by the hydrogen atoms. ISS spectra obtained on fluorinated PET samples show that the fluorination treatment results in the incorporation of fluorine with a slight change of the O/C ratio: this has been interpreted by the substitution of hydrogen atoms from the PET by fluorine which has already been observed on other polymers subjected to the same treatment. Both XPS and SSIMS analyses confirm these results. First, the SSIMS spectra obtained on the fluorinated samples are totally different from those obtained on the untreated PET samples: these spectra exhibit new peaks characteristic of fluorine containing molecular ions similar to those observed from fluorinated polymers such as PVDF or PTFE. Since the secondary ions formation involves ruptures of the polymer chains and some recombination reactions, it is difficult to decide from SSIMS on the exact sites on the PET chains where the hydrogen substitution by fluorine takes place. This was made possible with the help of XPS: the shape of the C1s peak after fluorination of the PET shows that the formation of new CF(x) species (x less-than-or-equal-to 2) occurs on the electron rich benzenic rings of PET rather than on the aliphatic parts of the PET chains. Finally, RBS has been used in order to estimate the depth at which the fluorination treatment has proceeded: this has been estimated to a few tenths of micrometer.

A conductometric biosensor for nitrite detection was developed using cytochrome c nitrite reductase (ccNiR) extracted from Desulfovibrio desulfuricans ATCC 27774 cells immobilized on a planar interdigitated electrode by cross-linking with saturated glutaraldehyde (GA) vapour in the presence of bovine serum albumin, methyl viologen (MV), Nafion, and glycerol. The configuration parameters for this biosensor, including the enzyme concentration, ccNiR/BSA ratio, MV concentration, and Nafion concentration, were optimized. Various experimental parameters, such as sodium dithionite added, working buffer solution, and temperature, were investigated with regard to their effect on the conductance response of the biosensor to nitrite. Under the optimum conditions at room temperature (about 25 degrees C), the conductometric biosensor showed a fast response to nitrite (about 10s) with a linear range of 0.2-120 microM, a sensitivity of 0.194 microS/microM [NO(2)(-)], and a detection limit of 0.05 microM. The biosensor also showed satisfactory reproducibility (relative standard deviation of 6%, n=5). The apparent Michaelis-Menten constant (K(M,app)) was 338 microM. When stored in potassium phosphate buffer (100mM, pH 7.6) at 4 degrees C, the biosensor showed good stability over 1 month. No obvious interference from other ionic species familiar in natural waters was detected. The application experiments show that the biosensor is suitable for use in real water samples.

International audience; An original approach based on X-ray photoelectron spectroscopy (XPS) is proposed to study the influence of the surrounding humidity on the hydrolysis-condensation reactions of five titanium alkoxides in thin films. More precisely, the influence of the nature of the ligands (propoxide, butoxide, isopropoxide, phenoxide, and 9H-carbazole-9-yl-ethyl-oxy) on the reaction rate was evidenced. The reaction advancement was evaluated by comparing XPS chemical compositions to theoretical compositions calculated for all the possible rates. XPS chemical environment information allowed validating the reliability of this approach through the evaluation of the condensation state. In both approaches, the influence of the steric hindrance on the reactivity of titanium alkoxides was highlighted to be similar to what has been previously observed in solution. Theses results corroborate the validity of our XPS approach to determine titanium alkoxide hydrolysis-condensation reactions in the specific application of thin films.

A conductometric biosensor for phosphate detection was developed using maltose phosphorylase (MP) from recombinant Escherichia coli immobilized on a planar interdigitated electrode by cross-linking with saturated glutaraldehyde (GA) vapour in the presence of bovine serum albumin (BSA). The process parameters for the fabrication of the mono-enzymatic sensor and various experimental variables such as the enzyme loading, time of immobilization in saturated GA vapour, working buffer solution and temperature were investigated with regard to their influence on sensitivity, detection limit, dynamic range, operational and storage stability. The biosensor can work well at the temperature between 20 degrees C and 50 degrees C, and reach 90% of steady-state conductance in about 10s. The sensor has two linear ranges, one is from 1.0 microM to 20 microM phosphate with a detection limit of 1.0 microM, and the other is between 20 microM and 400 microM phosphate. When stored in citrate buffer (0.1M, pH 6.0) at 4 degrees C, the biosensor showed good stability over two months. No obvious interference from other anionic species like SO(4)(2-), Cl(-), NO(3)(-), NO(2)(-) and HCO(3)(-) was detected. The biosensor is suitable for use in real water samples.

Oleic acid-coated magnetite has been encapsulated in biocompatible magnetic nanoparticles (MNP) by a simple emulsion evaporation method. The different parameters influencing the particles size were studied. Between these parameters, the stirring speed and the polymer concentration were found to influence positively or negatively, respectively, the MNP size which varied between 320 and 1500nm. The magnetite encapsulation efficacy was about than 90% yielding a high magnetite loading of up to 30% (w/w). X-ray diffraction showed that magnetite crystalline pattern was not modified after emulsification and solvent evaporation. The X-ray photoelectron spectroscopy (XPS) results indicated the presence of less than 0.1% of iron atoms at the nanoparticles surface. Vibration simple magnetometer (VSM) showed a superparamagnetic behaviour of the MNP and a saturation magnetization increasing with the increased magnetite amount used in formulation. Moreover, T(1) and T(2) relaxivities of MNP (4.7T, 20 degrees C) were 1.7+/-0.1 and 228.3+/-13.1s(-1)mM(-1), respectively, rendering them in the same category of known negative contrast agents which shorten the T(2) relaxation time. Therefore, by using an appropriate anticancer drug in their formulation, these magnetic nanoparticles can present a promising mean for simultaneous tumor imaging, drug delivery and real time monitoring of therapeutic effect.

Lanthanum-manganese based perovskites were prepared, both at atmospheric pressure (MW) and at higher pressure (MWHyd), under microwaves irradiation. Structural and physico-chemical properties of the catalysts were investigated using X ray diffraction, X-ray photoelectron spectroscopy (XPS), BET-sorption, and temperature programmed reduction-, or desorption coupled with mass spectrometry, (TPR-MS or TPD-MS). While MW and MWHyd catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation procedure. The influence of the nature of oxygen species, their amount and their mobility, evidenced by temperature programmed experiments, on the catalytic properties in catalytic combustion of methane in the presence and in the absence H 2 S has been studied.

The application of synthetic polymers in the growing field of materials for medical applications is illustrated by examples from recent work at the Materials Institute of the Swiss Federal Institute of Technology in Lausanne. The review highlights the need for functionalization and chemical control of material surfaces at a molecular/functional level. After a brief introduction into the surface chemical analysis tools, i.e., X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) combined with contact angle measurements, phosphorylcholine biomimicking polymers as well as immobilization of carbohydrates on polystyrene are presented.

Biological systems make considerable use of specific molecular interactions. Many biomolecules involved in biorecognition are glycosylated, the carbohydrate moiety playing an essential role. Controlled surface glycoengineering is thus of crucial importance in biosensing, cell guidance, and biomedical applications. This study describes the synthesis of an aryldiazirine-derivatized galactose and the functionalization of surfaces by carbohydrates using photochemical immobilization techniques. A photoactivatable glycosylated reagent was synthesized by addition of thiogalactopyranose to the maleimide group of N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-maleimidobutyr amide (MAD) to give N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-[3-thio (1-D-galactopyranosyl)succinimidyl]butyramide (MAD-Gal). The structure of the newly synthesized molecule was confirmed by UV spectroscopy, photoactivation, 1H NMR, and 13C NMR. MAD-Gal was immobilized on thin diamond films by photoactivation of the diazirine function (350 nm). Surface modification was investigated by XPS (X-ray photoelectron spectroscopy) and ToF-SIMS (time-of-flight secondary ion mass spectrometry). Imaging ToF-SIMS was applied to detect glycopatterns generated by mask-assisted lithography.

Static SIMS (SSIMS) has been used as an analytical tool for the study of the physicochemical changes following the surface treatments of polyolefin samples. First, the influence of the treatment duration has been investigated for nitrogen plasma and flame treated polypropylene (PP). Then, in order to confirm the interpretation of these SSIMS results, the influence of the plasma atmosphere and of the treatment duration on the surface modifications has been studied for hexatriacontane (C36H74), a model compound of linear saturated hydrocarbons. SSIMS results are discussed in light of the other complementary physicochemical characterizations presented previously, namely, surface energy measurements and XPS analyses.