G. Polzonetti

XPS study of MnO oxidation

Abstract The oxidation of a MnO layer has been studied by XPS at 400°C. Pure Mn oxides have been measured for comparison and the Mn oxidation states have been identified by Mn2p binding energy, Mn2p satellite structure, Mn3s multiplet splitting and valence spectra. A progressive oxidation of MnO to Mn2O3 without intermediate formation of Mn3O4 has been observed. Comparison of core and valence spectra seems to indicate that a thin layer of Mn2O3 is initially formed on top of MnO. At higher O2 exposure the MnO is completely oxidized to Mn2O3.

Covalent surface modification of titanium oxide with different adhesive peptides: surface characterization and osteoblast-like cell adhesion.

A fundamental goal in the field of implantology is the design of innovative devices suitable for promoting implant-to-tissue integration. This result can be achieved by means of surface modifications aimed at optimizing tissue regeneration. In the framework of oral and orthopedic implantology, surface modifications concern both the optimization of titanium/titanium alloy surface roughness and the attachment of biochemical factors able to guide cellular adhesion and/or growth. This article focuses on the covalent attachment of two different adhesive peptides to rough titanium disks. The capability of biomimetic surfaces to increase osteoblast adhesion and the specificity of their biological activity due to the presence of cell adhesion signal-motif have also been investigated. In addition, surface analyses by profilometry, X-ray photoelectron spectroscopy, and time of flight-secondary ion mass spectrometry have been carried out to investigate the effects and modifications induced by grafting procedures.

Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization.

Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

Self-assembled nanoparticles of functional copolymers for photonic applications

A modified emulsion copolymerization of phenylacetylene (PA) with hydrophilic monomers having different functions, i.e., acrylic acid (AA) and N,N-dimethylpropargylamine (DMPA) respectively, yields functionalized polymeric P(PA-co-AA) and P(PA-co-DMPA) nanoparticles. The systematic investigation on the experimental parameters affecting size, surface charge and polydispersity of the copolymers (initiator concentration, reaction time, cosolvent and PA/comonomer ratios) allows to modulate the nanoparticle physico-chemical properties. Spherical shaped particles with diameters in the range 80-500 nm, low polydispersity (PI values in the range 1.11-1.30) and different surface charge densities, between 0.44 and 2.87 microC/cm(2), have been consistently obtained and characterized by means of Dynamic Light Scattering (DLS), laser Doppler electrophoretic and Scanning Electron Microscopy (SEM) studies. XPS measurements have provided information on the nanoparticles chemical surface structure and suggest that AA and DMPA units are preferentially distributed on the surface of the spheres. The nanospheres self-assemble giving large domains (9.5 x 14.5 microm). Photonic analysis of the self-assembled copolymeric nanoparticles has been performed by means of Spectroscopic Ellipsometry (SE) and Bragg reflection spectroscopy, both of them demonstrating a three-dimensional photonic crystal property of these systems.

Study of chemical structure and conjugation length in organometallic Pt(II) oligomers and polymers containing 1,4-diethynylbenzene derivatives as bridging units

Abstract The synthesis of platinum containing organometallic rigid rod oligomers and polymers, of general formula—[PtL 2 (CC p C 6 H 4 (2,5-R) 2 CC)] n , where L=PPh 3 , PBu 3; R=H, OC 4 H 9 or OC 16 H 33 , has been carried out. The multinuclear macromolecules have been prepared by the Stille coupling in the extended one pot version. Oligomers of different chain lengths were obtained and fully characterised by means of spectroscopic techniques. Different organic spacers and precursor metal complexes have been employed in order to study and compare the reaction products. Well-defined oligomers were isolated and X-ray photoelectron spectroscopy technique provided information about the chain length and the nature of the end-groups. Luminescence and absorption studies of the newly synthesised Pt based poly-ynes are also reported. A correlation between the chain length, the nature of ligand phosphines and organic spacers with the optical properties was rationalised. The Pt metal centre played an important role in the conjugation, showing a red shift of absorption maxima upon increasing the number of repeating units. Band gaps of about 2.8–3.0 eV were found, corresponding to blue-light emission with a quantum efficiency up to about 3% for measurements performed in solution.

Self-Assembled Monolayers Based on Pd-Containing Organometallic Thiols: Preparation and Structural Characterization †

Multilayers and self-assembled monolayers of on-purpose-prepared organometallic thiolates, trans-[Pd(PBu(3))(2)(SCOCH(3))(2)], trans-[(C(6)H(5)C[triple bond]C)Pd(PBu(3))(2)(SCOCH(3))], and trans,trans-[(CH(3)COS)Pd(PBu(3))(2)(C[triple bond]C-C(6)H(4)-C(6)H(4)-C[triple bond]C)(PBu(3))(2)Pd(SCOCH(3))] were deposited onto gold surfaces. High-resolution X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure measurements allowed us to assess the anchoring of the organometallic thiols onto gold substrates; the interaction occurring at the interface; and their molecular orientation on the surface with tilt angles of about 30 degrees-40 degrees, depending on the investigated molecule. The molecule packing density/coverage was also assessed.

Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization.

Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brusts two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand.

Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids

In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol,trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl4−/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NOxwith the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction.

XPS of coordination compounds: Data on the electronic structure of a series of Cu(II) N,N′-cyclic substituted dithiocarbamates

Abstract A series of copper(II) dithiocarbomates Cudtc2 with dtc− = S, NH, NCH3, O) has been investigated by XPS. The compounds proved sufficiently stable under X-irradiation; b.e. data confirm substantial identity of the electronic structure of the metal chromophores throughout the series, in which remote ligand effects find evidence in a linear correlation between relative intensity of Cu2p 3 2 satellite peaks and variations of magnetic moments of the Cu(II) species.

Assessment of novel chemical strategies for covalent attachment of adhesive peptides to rough titanium surfaces: XPS analysis and biological evaluation

Bioactive molecules have been proposed to promote beneficial interactions at bone-implant interfaces for enhancing integration. The main objective of this study was to develop novel methods to functionalize oxidized titanium surfaces by the covalent immobilization of bioactive peptides, through selective reaction involving single functional groups. In the first protocol, an aminoalkylsilane was covalently linked to the Ti oxide layer, followed by covalent binding of glutaric anhydride to the free NH(2) groups. The carboxylic group of glutaric anhydride was used to condense the free N-terminal group of the side-chain protected peptide sequence. Finally, the surface was treated with trifluoroacetic acid to deprotect side-chain groups. In the second protocol, the peptide was directly anchored to the Ti oxide surface via UV activation of an arylazide peptide analogue. X-ray photoelectron spectroscopy analyses confirmed that modifications induced onto surface composition were in agreement with the reactions performed. The peptide density of each biomimetic surface was determined on the basis of radiolabeling and XPS derived reaction yields. The in vitro cellular response of the biomimetic surfaces was evaluated using a primary human osteoblast cell model. Cell adhesion, proliferation, differentiation, and mineralization were examined at initial-, short-, and long-time periods. In was shown that the biomimetic surface obtained through photoprobe-marked analogue that combines an easily-performed modification provides a favorable surface for an enhanced cellular response.