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Since implant surface is the region in contact with living tissue, corrosion resistance is an important property for biomedical implant materials. The deposition of biocompatible materials by magnetron sputtering is a viable surface modification method for improving the biocompatibility, corrosion resistance, and extends the life time of traditional biomedical implants. Titanium, niobium, and zirconium materials have excellent mechanical properties and corrosion resistance which make them potential candidates for coating implants. In this work, thin films of Ti, Nb, and Zr were deposited on Si(111) substrates in an oxygen/argon atmosphere to create models of biocompatible coatings. The chemical composition, morphology, Young’s modulus, and hardness of the three thin films were analyzed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), atomic force microscopy (AFM), and nanoindentation. It was found that all thin films were completely oxidized, had nanostructured grains, bulk uniformity, and good mechanical properties, thus thin TiO2, Nb2O5, and ZrO2 films can be considered as good candidates for bioactive implant coatings.

Nanometer-sized structures, surfaces and sub-surface phenomena have played an enormous role in science and technological applications and represent a driving-force of current interdisciplinary science. Recent developments include the atomic-scale characterization of nanoparticles, molecular reactions at surfaces, magnetism at the atomic scale, photoelectric characterization of nanostructures as well as two-dimensional solids. Research and development of smart nanostructured materials governed by their surface properties is a rapidly growing field. The main challenge is to develop an accurate and robust electronic structure description. The density of surface-related trap states is analyzed by transient UV photoconductivity and temperature-dependent admittance spectroscopy. An advanced application of thin films on shaped substrates is the deposition of catalytic layers on hollow glass microspheres for hydrogen storage controlled exothermal hydrolytic release. Surface properties of thin films including dissolution and corrosion, fouling resistance, and hydrophilicity/hydrophobicity are explored to improve materials response in biological environments and medicine. Trends in surface biofunctionalization routes based on vacuum techniques, together with advances in surface analysis of biomaterials, are discussed. Pioneering advances in the application of X-ray nanodiffraction of thin film cross-sections for characterizing nanostructure and local strain including in-situ experiments during nanoindentation are described. Precise measurements and control of plasma properties are important for fundamental investigations and the development of next generation plasma-based technologies. Critical control parameters are the flux and energy distribution of incident ions at reactive surfaces; it is also crucial to control the dynamics of electrons initiating non-equilibrium chemical reactions. The most promising approach involves the exploitation of complementary advantages in direct measurements combined with specifically designed numerical simulations. Exciting new developments in vacuum science and technology have focused on forward-looking and next generation standards and sensors that take advantage of photonics based measurements. These measurements are inherently fast, frequency based, easily transferrable to sensors based on photonics and hold promise of being disruptive and transformative. Realization of Pascal, the SI unit for pressure, a cold-atom trap based ultra-high and extreme high vacuum (UHV and XHV) standard, dynamic pressure measurements and a photonic based thermometer are three key examples that are presented.

International audience; We study a Au (25 nm)/Cr (10 nm) bilayer system as a model of mirror for the soft X‐ray energy range. The Au and Cr thin films are a few nanometer thick and are deposited on a float glass substrate. The sample is characterized by using 3 complementary techniques: soft X‐ray reflectivity, glow discharge optical emission spectrometry (GDOES), and time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS). Soft X‐ray reflectivity provides information about the thickness and roughness of the different layers, while GDOES is used to obtain the elemental depth profile of the stack and ToF‐SIMS to obtain the elemental and chemical depth profiles. GDOES and ToF‐SIMS have both a nanometer depth resolution. A coherent description of the bilayer stack is obtained through the combination of these techniques. It consists in 5 layers namely a surface contamination layer, a principal gold layer, a Au‐Cr mixed layer, a Cr layer, and another contamination layer at the top of the substrate.

The grafting of organic films on an aluminum surface with its native oxide is demonstrated in protic or aprotic media by various methods: (i) spontaneous reduction of aryldiazonium salts, (ii) simultaneous electrochemical grafting of diazonium salts and alkyl iodides, (iii) spontaneous reaction of perfluoroalkylamine in an organic solvent and (iv) photochemical grafting of acetonitrile. The films are characterized by IRRAS, XPS, electrochemistry, water contact angles and ToF-SIMS; the latter demonstrates that aryl groups derived from diazonium salts are attached by an O–aryl bond. With all methods, the organic layers are strongly attached to the aluminum surface as they resist ultrasonic cleaning. Superhydrophobic films can be obtained when perfluoroalkyl groups are bonded on the surface.

In order to address the complexity of chemical analysis of biological systems, time-of-flight secondary ion mass spectrometry (ToF-SIMS), x-ray photoelectron spectroscopy (XPS), and x-ray photoemission electron microscopy (XPEEM) were used for combined surface imaging of a biological tissue formed around a surface neural device after implantation on a nonhuman primate brain. Results show patterns on biological tissue based on extracellular matrix (ECM) and phospholipid membrane (PM) molecular fragments, which were contrasted through principal component analysis of ToF-SIMS negative spectrum. This chemical differentiation may indicate severe inflammation on tissue with an early case of necrosis. Quantification of the elemental composition and the chemical bonding states on both ECM-rich and PM-rich features was possible through XPS analysis from survey and high-resolution spectra, respectively. Variable amounts of carbon (68%-80.5%), nitrogen (10%-2.4%), and oxygen (20.8%-16.5%) were detected on the surface of the biological tissue. Chlorine, phosphorous sodium, and sulfur were also identified in lower extends. Besides that, analysis of the C 1s high-resolution spectra for the same two regions (ECM and PM ones) showed that a compromise between C-C (41.8 at. %) and C-N/C-O (35.6 at. %) amounts may indicate a strong presence of amino acids and proteoglycans on the ECM fragment-rich region, while the great amount of C-C (70.1 at. %) on the PM fragment-rich region is attributed to the large chains of fatty acids connected to phospholipid molecules. The micrometer-scale imaging of these chemical states on tissue was accomplished through XPEEM analysis. The C-C presence was found uniformly distributed across the entire analyzed area, while C-N/C-O and C=O were in two distinct regions. The combination of ToF-SIMS, XPS, and XPEEM is shown here as a powerful, noninvasive approach to map out elemental and chemical properties of biological tissues, i.e., identification of chemically distinct regions, followed by quantification of the surface chemical composition in each distinct region.

Controlling adsorption of proteins onto medical devices is a key issue for implant-related infections. As self-assembled monolayers (SAMs) on titanium oxide represent a good model to study the surface-protein interactions, TiO 2 surface properties were modified by grafting bisphosphonate molecules terminated with hydrophilic poly(ethylene glycol) groups and hydrophobic perfluoropolyether ones, respectively. Characterisation of the surface chemistry and surface topography of the modified surfaces was performed using XPS and atomic force microscopy (AFM). Quartz-crystal microbalance with dissipation (QCM-D) was used to determine the mass of adsorbed proteins as well as its kinetics. Poly(ethylene glycol)-terminated SAMs were the most effective surfaces to limit the adsorption of both BSA and fibrinogen in comparison to perfluorinated-terminated SAMs and non-modified TiO 2 surfaces, as expected. The adsorption was not reversible in the case of BSA, while a partial reversibility was observed with Fg, most probably due to multilayers of proteins. The grafted surfaces adsorbed about the same quantity of proteins in terms of molecules per surface area, most probably in monolayer or island-like groups of adsorbed proteins. The adsorption on pristine TiO 2 reveals a more important, non-specific adsorption of proteins.

International audience; Dynamic guidance of living cells is achieved by fine-tuning and spatiotemporal modulation on artificial polymer layers enabling reversible peptide display. Adjustment of surface composition and interactions is obtained by coadsorption of mixed poly(lysine) derivatives, grafted with either repellent PEG, RGD adhesion peptides, or T-responsive poly(N-isopropylacrylamide) strands. Deposition of mixed adlayers provides a straightforward mean to optimize complex substrates, which is here implemented to achieve (1) thermal control of ligand accessibility and (2) adjustment of relative adhesiveness between adjacent micropatterns, while preserving cell attachment during thermal cycles. The reversible polarization of HeLa cells along orthogonal stripes mimics guidance along natural matrices.

International audience; We report the elaboration of novel bio-sourced ecocatalysts for Heck and Suzuki cross-coupling reactions.Ecocatalysis is based on the recycling of metals issued from phytoremediation or rehabilitation, and aninnovative chemical valorization of the subsequent biomass in the field of catalysis. Here, we describe theefficient palladium accumulation by plants (Brassica juncea, Lolium multiflorum) via rhizofiltration. Takingadvantage of the remarkable ability of the selected plants to accumulate Pd(II) species into their roots,these latter can be directly used for the preparation of ecocatalysts, called Eco-Pd®. The formed Eco-Pd®catalysts are thoroughly characterized via ICP-MS, XRD, XPS, TEM, SEM in order to elucidate the chemicalcomposition and morphology of the formed materials. Significant differences to conventional Pd-basedcatalysts such as palladium(II) chloride can principally be related to a particular Lewis acid behavior ofthe Eco-Pd®catalysts. Finally, the obtained Eco-Pd®appear as highly active catalysts in Heck and Suzukicross-coupling reactions necessitating considerably lower Pd quantity compared to precedently reportedbio-sourced palladium containing catalysts.

This contribution reports on grafting of bioactive polymers such as poly(sodium styrene sulfonate) (polyNaSS) onto titanium (Ti) surfaces. This grafting process uses a modified dopamine as an anchor molecule to link polyNaSS to the Ti surface. The grafting process combines reversible addition-fragmentation chain transfer polymerization, postpolymerization modification, and thiol-ene chemistry. The first step in the process is to synthetize architecture controlled polyNaSS with a thiol end group. The second step is the adhesion of the dopamine acrylamide (DA) anchor onto the Ti surfaces. The last step is grafting polyNaSS to the DA-modified Ti surfaces. The modified dopamine anchor group with its bioadhesive properties is essential to link bioactive polymers to the Ti surface. The polymers are characterized by conventional methods (nuclear magnetic resonance, size exclusion chromatography, and attenuated total reflection-Fourier-transformed infrared), and the grafting is characterized by x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and quartz crystal microbalance with dissipation monitoring. To illustrate the biocompatibility of the grafted Ti-DA-polyNaSS surfaces, their interactions with proteins (albumin and fibronectin) and cells are investigated. Both albumin and fibronectin are readily adsorbed onto Ti-DA-polyNaSS surfaces. The biocompatibility of modified Ti-DA-polyNaSS and control ungrafted Ti surfaces is tested using human bone cells (Saos-2) in cell culture for cell adhesion, proliferation, differentiation, and mineralization. This study presents a new, simple way to graft bioactive polymers onto Ti surfaces using a catechol intermediary with the aim of demonstrating the biocompatibility of these size controlled polyNaSS grafted surfaces.

Tailoring the surface chemistry of gold nanorods is a key factor for successful applications in biology, catalysis, and sensing. Here, we report on the use of the diazonium salt chemistry for the functionalization of gold nanorods enabling the formation of strongly attached organic layers around the gold cores. The precise nature of the interface between the gold surface and the diazonium-derived aryl layers was probed by XPS, ToF-SIMS, SERS, and DFT. It was shown that the CTAB surfactant was partially exchanged by the diazonium salt which dediazonizes spontaneously to form Au–C covalent bonds with the surface. Interestingly, the silver used during the synthesis of gold nanorods and still present at their surface appears to be also involved in the grafting mechanism with Ag–C covalent bonds detected by ToF-SIMS. From this result, it is clear that the interfacial properties and reactivity of gold nanorods synthesized by the silver(I)-assisted seed mediated growth approach are strongly influenced by the pre...

A challenge in molecular spintronics is to control the magnetic coupling between magnetic molecules and magnetic electrodes to build efficient devices. Here we show that the nature of the magnetic ion of anchored metal complexes highly impacts the exchange coupling of the molecules with magnetic substrates. Surface anchoring alters the magnetic anisotropy of the cobalt(II)-containing complex (Co(Pyipa)2), and results in blocking of its magnetization due to the presence of a magnetic hysteresis loop. In contrast, no hysteresis loop is observed in the isostructural nickel(II)-containing complex (Ni(Pyipa)2). Through XMCD experiments and theoretical calculations we find that Co(Pyipa)2 is strongly ferromagnetically coupled to the surface, while Ni(Pyipa)2 is either not coupled or weakly antiferromagnetically coupled to the substrate. These results highlight the importance of the synergistic effect that the electronic structure of a metal ion and the organic ligands has on the exchange interaction and anisotropy occurring at the molecule–electrode interface., Controlling the magnetic response of a molecular device is important for spintronic applications. Here the authors report the self-assembly, magnetic coupling, and anisotropy of two transition metal complexes bound to a ferrimagnetic surface, and probe the role of the nature of the transition metal ion.