Synthesis and analytical characterisation of copper-based nanocoatings for bioactive stone artworks treatment

Biological agents play an important role in the deterioration of cultural heritage causing aesthetic, biogeophysical and biogeochemical damages. Conservation is based on the use of preventive and remedial methods. The former aims at inhibiting biological attack, and the latter aims at eradicating the biological agents responsible for biodeterioration. Here, we propose the preparation and the analytical characterisation of copper-based nanocoating, capable of acting both as a remedy and to prevent microbial proliferation. Core–shell CuNPs are mixed with a silicon-based product, commonly used as a water-repellent/consolidant, to obtain a combined bioactive system to be applied on stone substrates. The resulting coatings exert a marked biological activity over a long period of time due to the continuous and controlled release of copper ions acting as biocides. To the best of our knowledge, this is the first time that a multifunctional material is proposed, combining the antimicrobial properties of nanostructured coatings with those of the formulations applied to the restoration of stone artworks. A complete characterisation based on a multi-technique analytical approach is presented.     

Preparation and characterization of hybrid nanoparticles based on chitosan and poly(methacryloylglycylglycine)

CeO₂–MnO _x composites possessing rod-like morphology (fixed mole proportion of Ce/Mn) were synthesized through hydrothermal method and chosen as supporters to load PdO nanoparticles (PdO/Ce _x Mn_1–x ). The size of loaded PdO nanoparticles is about 2 nm. The catalytic behaviors of supported catalysts were examined through the complete catalytic oxidation of benzene. The results illustrated that the activities of supported catalysts were enhanced greatly as compared to unsupported, and the completely conversion temperature of benzene was reduced to ca. 250 °C. The effect of noble metal species (PdO) addition on the catalytic property and crystal structure of composites was researched in detail. The data revealed that the interaction between PdO and supporter, and intrinsic properties of supporter resulted in the enhancement of catalytic abilities.     

A pyrolysis-GC–MS investigation of poly(vinyl phenyl ketone)

The thermal decomposition process and pyrolysis products of poly(vinyl phenyl ketone) (PVPK) were investigated by thermogravimetric analysis (TGA) and on-line pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS). TGA showed a largest weight loss rate around 380 °C. Py-GC–MS was used for the qualitative analysis of the pyrolysis products at 350, 500, 600, 700 and 850 °C. The major volatile thermal decomposition product was found to be 1-phenyl-2-propenone, which dominated all other volatile species especially under the least severe pyrolysis conditions (<600 °C). At higher temperatures a much wider range of pyrolysis products was obtained. The results have been interpreted assuming that primary random chain scission reactions occur followed by typical unzipping mainly producing monomer units; detachment of the side-group occurs only under more severe pyrolysis conditions. Py-GC–MS showed to be effective in PVPK detection in ink and paint formulations.     

Analytical characterization of chitosan nanoparticles for peptide drug delivery applications

Chitosan-cyclodextrin hybrid nanoparticles (NPs) were obtained by the ionic gelation process in the presence of glutathione (GSH), chosen as a model drug. NPs were characterized by means of transmission electron microscopy and zeta-potential measurements. Furthermore, a detailed X-ray photoelectron spectroscopy study was carried out in both conventional and depth-profile modes. The combination of controlled ion-erosion experiments and a scrupulous curve-fitting approach allowed for the first time the quantitative study of the GSH in-depth distribution in the NPs. NPs were proven to efficiently encapsulate GSH in their inner cores, thus showing promising perspectives as drug carriers.     

Concerning the electroactivity of hydrogen in nitrate melts: A critical discussion in the light of recent hypotheses and suggestions

A critical discussion of the electroactivity of hydrogen in nitrate melts is reported. The consistency of recent alternative models, proposed by other authors, to explain our experimental results has been tested by additional experiments, in part suggested by those authors themselves. Our mechanistic model seems, at present, the only consistent way to interpret the whole of the phenomena related to the known hydrogen systems in nitrate melts.     

Synthesis,analytical characterization and bioactivity of Ag and Cu nanoparticles embedded in poly-vinyl-methyl-ketone films

The electrosynthesis of copper and silver core-shell nanoparticles (NPs) by the sacrificial anode technique, employing tetraoctylammonium (TOA) salts as base electrolyte for the first time, is described. These surfactants were selected because they combine high NP stabilizing power with useful disinfecting properties. The resulting colloids were mixed with a solution of an inert dispersing polymer and used to prepare nanostructured composite thin films. The morphologies and chemical compositions of the nanomaterials were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The TEM reveals that the average core diameter of the metal NPs ranges between 1.7 and 6.3 nm, as a function of the nature of the metal and of the electrosynthesis conditions, and does not change significantly upon inclusion in the polymer matrix. An appreciable concentration of the metal is detected on the nanoparticle surface by XPS. High-resolution XP spectra indicate that both copper and silver are present at zero oxidation state in all of the materials (colloids and composite films). This demonstrates the high efficiency of the surfactant at controlling the morphology and the chemical composition of the nanodispersed metal in both the as-synthesized colloid and in the polymeric dispersion. The nanocoatings are shown to exert a marked inhibitory effect on the growth of eukaryote and prokaryote target microrganisms, and experimental evidence of a synergic disinfecting effect due to the surfactant and the nanodispersed metal is provided. On the basis of these stability and bioactivity results, it is clear that Cu-NPs and Ag-NPs are suitable for application in disinfecting or antifouling paint and coating formulations.Electronic Supplementary Material Supplementary material is available for this article at Dedicated to the memory of Wilhelm Fresenius     

Electrosynthesis and analytical characterization of PMMA coatings on titanium substrates as barriers against ion release

The performance of polyacrylic coatings as barrier films against corrosion of titanium-based orthopaedic implants was investigated. In particular, poly(methyl methacrylate) (PMMA) was electrosynthesized on titanium substrates by electro-reductive processes from aqueous monomer solutions. The obtained PMMA coatings were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The effect of an annealing treatment on the morphology of coatings with respect to uniformity and porosity of films was assessed by scanning electron microscopy (SEM). An inductively coupled plasma-mass spectrometry (ICP-MS) technique was used for ion concentration measurements in ion release tests performed on TiAlV sheets modified with PMMA coatings (annealed and unannealed). Results indicated that the annealing process produces coatings with considerable anticorrosion performances.Electronic Supplementary Material Supplementary material is available for this article at