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Worldwide, over 20 million patients suffer from bone disorders annually. Bone scaffolds are designed to integrate into host tissue without causing adverse reactions. Recently, chitosan, an easily available natural polymer, has been considered a suitable scaffold for bone tissue growth as it is a biocompatible, biodegradable, and non-toxic material with antimicrobial activity and osteoinductive capacity. In this work, chitosan was covalently and selectively biofunctionalized with two suitably designed bioactive synthetic peptides: a Vitronectin sequence (HVP) and a BMP-2 peptide (GBMP1a). Nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) investigations highlighted the presence of the peptides grafted to chitosan (named Chit-HVP and Chit-GBMP1a). Chit-HVP and Chit-GBMP1a porous scaffolds promoted human osteoblasts adhesion, proliferation, calcium deposition, and gene expression of three crucial osteoblast proteins. In particular, Chit-HVP highly promoted adhesion and proliferation of osteoblasts, while Chit-GBMP1a guided cell differentiation towards osteoblastic phenotype.

In recent years the biomedical research has focused on new metal-based anticancer drugs. Among them Cu-based antitumor agents are arising some attention based on the observation that endogenous metals appear to be less toxic toward normal cells with respect to cancer ones. Conjugating the Cu(II) complexes with hydrophilic gold nanoparticles (Au-NPs) appears a promising way, suitable to improve the complexes solubility and stability in water and to raise their bioavailability. In this context, we investigated the valence state and coordination chemistry of Cu for a selection of Cu-complexes suitable for grafting on Au-NPs. The Cu K-edge XAFS data were analysed in the near edge (XANES) and extended (EXAFS) regions to obtain preliminary characterization aimed at understanding local coordination chemistry and electronic structure of Cu.

Self-assembling peptides (SAPs) were investigated by means of XPS and Angular Dependent NEXAFS spectroscopies, with the aim to probe the influence of pH and Ionic Strength conditions on the chemical structure and molecular organization of SAPs anchored on titania surfaces. XPS at the C1s, N1s, O1s core levels allowed to study surfaces and biomolecule/substrate interfaces. NEXAFS data allowed ascertaining that SAPs molecular structure is preserved upon grafting to the titania surface. Angular Dependent NEXAFS was used to investigate the influence of environmental conditions on the molecular organization behaviour. The objective of our study was to establish a set of methodologies for obtaining arrangements of well-organized biomolecules on scaffolds surfaces as a basic technology to develop and optimize cells adhesion and proliferation for tissue engineering applications.

Self-complementary amphiphilic oligopeptides, consisting of an alternation of hydrophobic and hydrophilic amino acids and of positively and negatively charged groups can generate extended ordered structures by self-assembling (SA) from aqueous solutions, and have been successfully tested as promising candidates for scaffolds in several fields of tissue engineering. In this paper we present a systematic XPS, NEXAFS and FTIR investigation carried out on a series of SA peptides consisting of different selected sequences of 16 residues, with the aim of determining the effect of side chains length on molecular arrangement and orientation. Peptides were immobilized on the surface of titanium, a well known biocompatible material, or deposited as thick films on inert gold surfaces. FTIR analysis yields information on the backbone conformation. XPS spectroscopy was used to investigate the peptide adsorption on the TiO 2 surface. The orientation of the peptide chains was studied by angular-dependent NEXAFS. The performed spectroscopical characterization leads to widely investigate the physical properties of biopolymers–peptide coatings.

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.

Peptides consisting of an alternation of hydrophobic and hydrophilic (positively and negatively charged) amino acids can generate extended ordered structures by self-assembling (SA) from aqueous solutions. In this paper we present XPS, near-edge X-ray absorption fine structure (NEXAFS) and Fourier transform infrared (FTIR) investigations on a series of SA peptides with the aim of determining the effect of side-chain length on molecular arrangement and orientation. Peptides were immobilised on the surface of titanium, a well-known biocompatible material, or deposited as thick films on inert gold surfaces. FTIR analysis yields information on the backbone conformation. XPS spectroscopy was used to investigate the peptide adsorption on the TiO 2 surface. The orientation of the peptide chains was investigated by angular-dependent NEXAFS.

The adsorption on TiO2 surface of two dipeptides AE (L-alanine-L-glutamic acid) and AK (L-alanine-L-lysine), that are "building blocks" of the more complex self-complementary amphiphilic oligopeptides and are therefore a good model in the interpretation of the complex peptide spectra, has been investigated both theoretically and experimentally. The chemical structure and composition of thin films of both dipeptides on TiO2. were investigated by XPS (X-ray photoelectron spectroscopy). Theoretical ab-initio calculations (Delta SCF) were also performed to simulate the spectra allowing a direct comparison between experiment and theory.

A near-edge x-ray absorption fine structure (NEXAFS) spectroscopy investigation on the electronic structure of some novel pi-conjugated organometallic polymers is presented. The investigated materials consist of Pt and Pd(II) complex units linked together through sigma-bonded organic spacers of ethynyl-thiophene type in a polymeric array. The C K-edge NEXAFS spectra were interpreted by comparison with literature data and with the spectra of reference samples. The linking between the thiophene rings and alkyne groups produces a splitting of the C1s --> pi* peak observed in the spectra of the thiophene systems. Angle-dependent measurements, performed at normal and grazing incidence of the linearly polarized photons, evidenced a preferential orientation of the polymer chains with an average tilt angle of 45 degrees for the thiophene moieties

New features of the interface between chromium and Pd-DEBP, [–Pd(PBu 3 ) 2 –CC–C 6 H 4 –C 6 H 4 –CC–] n , a π-conjugated organometallic polymer, were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Analysis of the C1s peak structure at increasing Cr coverage reveals that chromium reacts preferentially with the conjugated DEBP moiety to form carbide-like species; phosphide-like species are also produced, involving mainly the P–C bond. Investigations of the XPS signals intensity variations upon Cr coverage and AFM measurements indicate a cluster growth of chromium on the Pd-DEBP surface; the interdiffusion between the deposited metal and the polymer film and the surface localisation of the phosphide and carbide species were also evidenced.

The polymerization reactions of ethynylfluorenol (EFl) in the presence of Rh(I), Pt(II), Pd(II) and WCl6 catalysts have been investigated. The polymer (PEFl) is air stable and soluble; in solution PEFl slowly releases some of the pendent groups which are converted into 9-fluorenone. Upon doping, enhancement of the conductivity up to about 10 orders of magnitude can be achieved. X.p.s. measurements performed on I2-doped PEFl suggest that I−5 is the major doping species. An interesting reversible response to relative humidity variations is found for FeCl3-doped samples.