In this study, a preventive method for fighting bio-deterioration of stone substrates is proposed. This is based on the use of bioactive zinc oxide nanoparticles (ZnO-NPs), which are able to exert a marked biological activity over a long period of time due to their peculiar structure. ZnO-NPs are synthesised by a simple and reproducible electrochemical procedure. The nanomaterials are embedded in consolidant/ water-repellent matrices to obtain nanostructured coatings. Commonly used products based on tetraethoxysilane and/or polysiloxanes were tested. The resulting nanomaterials were fully characterised by X-ray photoelectron spectroscopy (XPS) to investigate the amount and composition of the NPs and the behaviour of the nanocomposites. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the study of the release of metal from the composites when put in contact with artificial rainwater. The nanocomposites were applied to specimens composed of three different types of stone and chromatic changes upon curing were measured by spectrophotocolorimetry. Finally, morphological characterization by scanning electron microscopy (SEM) was performed. The bioactivity of ZnO-NPs nanocomposites was also assessed in preliminary tests against Aspergillus niger fungus

A new class of nano-antimicrobials was developed by Ion Beam co-Sputtering of ZnO and polytetrafluoro_ ethylene targets. The resulting nanostructured coatings combine the antimicrobial properties of ZnO nanoparticles with the water repellence and anti-stain characters of the dispersing fluoropolymer (CFx). ZnO-CFx nanocomposites were prepared varying ZnO volume fraction (φ) in the CFx matrix by tuning the sputter- ing deposition parameters. Morphological analysis confirmed the presence of homogenously distributed ZnO nanoclusters in the polymer. ZnO loadings ranging in the 0.05-0.15 interval were explored and the nano-composites were characterized by X-ray Photoelectron Spectroscopy (XPS) to investigate their surface chemical composition. XPS spectra evidenced a high degree of polymer defluorina-tion along with the formation of ZnF2 at increasing φ valu-es. Zn speciation was performed on Zn L3M45M45 Auger signal. Coatings bioactivity was assessed against Escheri-chia coli, Staphylococcus aureus, and Kluyveromyces marxianus. At φ ≥ 0.10, ZnO-CFx composites exhibited appreciable antibacterial activity, irrespective of the target organism.

Escherichia coli (E. coli) is one of the most important foodborne pathogens to the food industry responsible for diseases as bloody diarrhea, hemorrhagic colitis and life-threatening hemolytic–uremic syndrome. For controlling and eliminating E. coli, metal nano- antimicrobials (NAMs) are frequently used as bioactive systems for applications in food treatments. Most NAMs provide controlled release of metal ions, eventually slowing down or completely inhibiting the growth of undesired microorganisms. Nonetheless, their antimicrobial action is not totally unraveled and is strongly dependent on metal properties and environmental conditions. In this work, we propose the use of matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry as a powerful tool for direct, time efficient, plausible identification of the cell membrane damage in bacterial strains exposed to copper-based antimicrobial agents, such as soluble salts (chosen as simplified AM material) and copper nanoparticles. E. coli ATCC 25922 strain was selected as ‘training bacterium’ to set up some critical experimental parameters (i.e. cell concentration, selection of the MALDI matrix, optimal solvent composition, sample preparation method) for the MS analyses. The resulting procedure was then used to attain both protein and lipid fingerprints from E. coli after exposure to different loadings of Cu salts and NPs. Inter- estingly, bacteria exposed to copper showed over-expression of copper binding proteins and degradation of lipids when treated with soluble salt. These findings were completed with other investigations, such as microbiological experiments.

The determination of the oxidation state and structural role of transition metals in minerals is a crucial challenge. XPS has proven to have a great potential in probing the site distribution and chemical states of Fe and Ti transition elements, provided that the right method to process the spectra is used. XPS spectra of these elements have the 2p core level region usually rich of features but the choice of the method for background removing can seriously affect the results of the quantitative analysis. Single crystals of brookite (TiO2) and natural micas (phlogopites) are investigated to examine the ef- fect of background subtraction on Ti2p and Fe2p signals. The backgrounds used are: (1) the “Linear” background; (2) the traditional “Shirley” background; (3) three different Tougaard-like backgrounds; and (4) the more recent “shape parameter, κ” method. In the case of the studied natural micas, the Fe chemical state proportion (Fe2+/Fetot) obtained with the corrected spectra varies by 10%. It is shown that TiO2 oxides are not suitable as standard for octahedral Ti4+ signal in the studied micas. The “shape parameter, κ” method proves to provide supplementary information useful for a full interpretation of XPS signals.

Si tratta di un sensore a transistore, cos’ come del suo array, capace di rivelare, in modo affidabile, selettivo e label-free fino ad una singola molecola di DNA così come di anticorpi e peptidi. noltre il semiconduttore usato è un composito nanostrutturato a base di un polimero semiconduttore, facile da preparare, scalabile ed economico, è anche particolarmente stabile quando impiegato in diretto contatto con l’acqua.