Surfactant hydrogels for the dispersion of carbon-nanotube-based catalysts.

Novel hydrogel phases based on positively charged and zwitterionic surfactants, namely, N-[p-(n-dodecyloxybenzyl)]-N,N,N-trimethylammonium bromide (pDOTABr) and p-dodecyloxybenzyldimethylamine oxide (pDOAO), which combine pristine carbon nanotubes (CNTs), were obtained, thus leading to stable dispersions and enhanced cross-linked networks. The composite hydrogel featuring a well-defined nanostructured morphology and an overall positively charged surface was shown to efficiently immobilise a polyanionic and redox-active tetraruthenium-substituted polyoxometalate (Ru4POM) by complementary charge interactions. The resulting hybrid gel has been characterised by electron microscopy techniques, whereas the electrostatic-directed assembly has been monitored by means of fluorescence spectroscopy and ζ-potential tests. This protocol offers a straightforward supramolecular strategy for the design of novel aqueous-based electrocatalytic soft materials, thereby improving the processability of CNTs while tuning their interfacial decoration with multiple catalytic domains. Electrochemical evidence confirms that the activity of the catalyst is preserved within the gel media.

Electrochemical polymerization of allylamine copolymers.

We describe for the first time the electro-oxidative synthesis and passivating properties of surface films of poly(allylamine) and copolymers of allylamine and diallylamine. Cyclic voltammetry and impedance spectra show that the films exhibit high charge-transfer resistance and that the addition of diallylamine causes improvements in the compactness and stability toward swelling of the films when compared to both allylamine and diallyamine, leading to coatings with high charge-transfer resistance up to 70 MΩ. We also show that removing oxygen before the polymerization further improves the films' passivating properties.

Localization of proteins in paint cross-sections by scanning electrochemical microscopy as an alternative immunochemical detection technique.

The qualitative identification of proteinaceous substances, as well as their location within a complex paint stratigraphy, is one of the most challenging issues in the characterization of painting materials. Nevertheless, information on paint components represent a crucial task for studies concerning both the ancient painting techniques adopted and the state of conservation, being fundamental investigations for the selection of appropriate conservation actions. The present research was aimed at developing a new detection approach for the immunochemical localization of ovalbumin in paint cross-sections based on the use of scanning electrochemical microscopy (SECM). The immunochemical analyses were performed using an anti-ovalbumin primary antibody and a secondary antibody labelled with horseradish peroxidase (HRP). SECM measurements were performed in feedback mode using benzoquinone (BQ)/hydroquinone (H2Q) redox couple. In presence of hydrogen peroxide (H2O2), HRP catalyzes the re-oxidation of H2Q to BQ and the increment of BQ concentration in correspondence of the target protein was detected by SECM through the electrochemical reduction of the regenerated BQ at the microelectrode. Indeed, the localization of ovalbumin was possible thanks to a clear discrimination of SECM currents, achieved by the comparison of the measurements recorded before and after H2O2 administration, based on the HRP on/off approach. The method was evaluated both on samples from standard mocks-up and on a historical sample, collected from a Renaissance wood painting. The obtained results were promising, foreseeing a wider application of SECM on cultural heritage researches.

Monocyclic ß-lactams as antibacterial agents: facing antioxidant activity of N-methylthio-azetidinones.

A series of N-methylthio-ß-lactams with antibacterial activity were thoroughly evaluated as antioxidants. We found that only the presence of a polyphenolic moiety anchored to the ß-lactam ring ensured an adequate antioxidant potency. New compounds, efficiently combining in one structure antioxidant and antibacterial activity, may provide a promising basis for the development of new leads useful in adverse clinical conditions such as in cystic fibrosis patients, in whom colonization by MRSA and epithelial damage by chronic pulmonary oxidative stress take place.