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Nanoscale disassembly of mussel-inspired polydopamine (PDA) in ionic liquids (ILs) was recently shown to induce an electron paramagnetic resonance (EPR)-detectable reorganization of free radical centers in the resulting nanoparticles (NPs) in an IL-controlled manner. Herein, we report electrical impedance spectroscopy (EIS) data showing that PDA NPs produced by suspending samples obtained in Tris and bicarbonate buffer (PDA-T and PDA-C) in different ILs display different redox activity as a result of structural control combined with IL-surface interactions. In particular, susceptibility to oxidation was found to correlate closely with the spin density in an ion pair-tunable fashion in ILs. Structural control over free radical properties and redox behavior of PDA NPs in ILs opens novel perspectives for the rational design of functional nanovectors of possible interest for drug delivery and theranostic applications.

Developing effective strategies to increase the chemical stability and to fine-tune the physico-chemical properties of melanin biopolymers by rational control of π-electron conjugation is an important goal in materials science for biomedical and technological applications. Herein we report that poly-1,8-dihydroxynaphthalene (pDHN), a non-nitrogenous, catechol-free fungal melanin mimic, displays a high degree of structural integrity (from MALDI-MS and CP/MAS 13 C NMR analysis), a strong radical scavenging capacity (DPPH and FRAP assays), and an unusually intense EPR signal (g=2.0030). Morphological and spectral characterization of pDHN, along with deassembly experiments in ionic liquids, indicated amorphous aggregates of small globular structures with an estimated stacking distance of 3.9 A and broadband absorption throughout the visible range. These results indicate that DHN-based melanins exhibit a high structural integrity and enhanced antioxidant and free-radical properties of potentially greater biomedical and technological relevance than for typical indole-based eumelanins.

Asymmetric nanostructures can mimic a chiral response when circular polarized light interacts with the structures under particular angle of incidence [1]. This phenomenon is called ‘extrinsic chirality’ and usually is present under linear optical investigation with low visibility. Due to the fact that optical second harmonic generation is possible only in samples with some degree of asymmetry, this can be used in order to investigate the extrinsic chirality with a background free technique, thus inducing a high visibility of the artificial circular dichroism [2,3]. Here we present the second harmonic generation (SHG) measurements obtained on samples composed by GaAs nanowires grown on silicon. The wires present resonant leaky modes around 800nm and at 400nm due to the high refractive index contrast ratio between wires and air, even if these wavelengths lie on the absorption band of GaAs [4]. The measurements performed on this sample present good SHG signal due to the second order nonlinear term of GaAs, but did not present any circular dichroism (SHG-CD). By coating the sample with a 20nm thin layer of gold deposited asymmetrically, by evaporating the metal only from one side of the nanowires, the symmetry of the structure is broken, thus induced high SHG-CD. The SHG-CD is measured by shining the sample with circular polarized pump light at the fundamental wavelength of 800nm and by revealing the second harmonic signal at 400nm in s or p polarization, as a function of sample rotation. Four samples were measured with GaAs wires of about 5 micron in length with different diameters ranging from 140nm to 200nm. In this case it is possible to explore different resonance conditions and different SHG-CD is revealed. For each sample, the measured were carried out before and after the asymmetric gold layer deposition, thus allowing direct comparison of the results. References [1] A. Belardini, M. C. Larciprete, M. Centini, E. Fazio, C. Sibilia, D. Chiappe, C. Martella, A. Toma, M. Giordano, and F. Buatier de Mongeot, Phys. Rev. Lett. 107, 257401 (2011). [2] A. Belardini, M. Centini, G. Leahu, D. C. Hooper, R. Li Voti, E. Fazio, J. W. Haus, A. Sarangan, V. K. Valev, C. Sibilia, Sci. Rep. 2016, 6, 31796. [3] G. Leahu, E. Petronijevic, A. Belardini et al., Adv. Optical Mater. 2017, 1601063 (2017). [4] G. Leahu, E. Petronijevic, A. Belardini, M. Centini, R. Li Voti, T. Hakkarainen, E. Koivusalo, M. Guina, C. Sibilia. Sci. Rep. 7, 2833 (2017).

Owing to economic reasons, the textile dyeing industry generally employs traditional and absolutely no-eco-friendly processes: very large quantities of water are indeed required together with a large number of added chemicals which represent dramatic environmental issues. In order to improve the sustainability of the process, we have investigated the dyeing of wool, polyester, and cotton with disperse Red 13 using ionic liquids as the sole additive. The results obtained in isothermal dyeing at 95 C show an outstanding effect of the ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium chloride. This ionic liquid assures efficient dyeing of polyester and wool in open vessels, in the absence of whichever auxiliary agent with total dyebath exhaustion, thus allowing in principle the recycling of the dye bath! The environmental benefits arising from the substitution of a number of usually employed auxiliary agents with only an ionic liquid are highlighted together with the economic ones. This article reports for the first time, to the best of our knowledge, dyeing processes for several kinds of fibers (cotton, wool, and polyester) employing exclusively three components: pure disperse dye, water, and an appropriate ionic liquid. (Figure Presented).

Despite the growing scientific and technological relevance of polydopamine (PDA), a eumelanin-like adhesive material widely used for surface functionalization and coating, knowledge of its structural and physicochemical properties, including in particular the origin of paramagnetic behavior, is still far from being complete. Herein, we disclose the unique ability of ionic liquids (ILs) to disassemble PDA, either as a suspension or as a thin film, up to the nanoscale, and to establish specific interactions with the free radical centers exposed by deaggregation of potential investigative value. Immersion of PDA-coated glasses into four different ILs ([C1C1im][(CH3O)HPO2], [C1C1im]- [(CH3O)CH3PO2], [C1C1im][(CH3O)2PO2], [N1888][C18:1]) at room temperature caused the fast and virtually complete removal of the coating as determined by UV−visible spectroscopy and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) analysis of the colored supernatants from PDA suspensions in ILs revealed the presence of nanostructures not exceeding 50 nm in diameter. Electron paramagnetic resonance (EPR) analysis indicated profound IL-dependent modifications in signal intensity, line-width, and g-factor values of PDA. These differences were interpreted in terms of a partial conversion of C-centered radicals into O-centered semiquinone-type components following destacking and interaction with the anion component in ILs. The discovery of ILs as a powerful tool to disassemble PDA under mild conditions provides a new entry both to detailed investigations of this biopolymer on the nanoscale and to mild removal of coatings from functionalized surfaces, greatly expanding the scope of PDA-based surface functionalization strategies.

N -Alkyl- N -methylmorpholinium and N -alkyl substituted 1,4-diazabicyclo[2.2.2]octane (DABCO) based ionic liquids (ILs), N -alkyl-DABCO, bearing short alkyl chains are characterised by a low toxicity to Vibrio fischeri , although toxicity significantly increases on increasing the alkyl chain length. Alkyl chain length affects also biodegradability in the 28 days tests; the higher level of biodegradation was found in both the series in the case of the ethyl (C2) derivatives. In the case of N -ethyl DABCO based IL, although biodegradability is still around 40%, and consequently this IL cannot be classified as “readily biodegradable”, this value is similar to the more biodegradable functionalized imidazolium based ILs.

The generalized Snell's law of refraction was introduce by F. Capasso in 2011. One consequence of the law is that resonant metallic nanostructures at the interface between two dielectrics can bent the light in a controlled way. Alternatively, by measuring the bent of a beam of light induced by a nanopatterned metallic surface it is possible to retrieve information on the surface morphology. Here we show that deviation measurements of the light passing through curved metallic nanowires deposited on a glass slide gives information on the morphology only when the resonance is excited. Full Text: PDF References N. Yu, P. Genevet, M.A. Kats, F. Aieta, J.-P. Tetienne, F. Capasso, Z. Gaburro, "Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction", Science 334, 333 (2011). CrossRef X. Ni, N.K. Emani, A.V. Kildishev, A. Boltasseva, V.M. Shalaev, "Broadband Light Bending with Plasmonic Nanoantennas", Science 335, 427 (2012). CrossRef N. Engheta, "Antenna-Guided Light", Science 334, 317 (2011). CrossRef F. Aieta, P. Genevet, M.A. Kats, N. Yu, R. Blanchard, Z. Gaburro, F. Capasso, "Aberration-Free Ultrathin Flat Lenses and Axicons at Telecom Wavelengths Based on Plasmonic Metasurfaces", Nano Lett. 12, 4932 (2012). CrossRef A. Belardini, F. Pannone, G. Leahu, M.C. Larciprete, M. Centini, C. Sibilia, C. Martella, M. Giordano, D. Chiappe, F. Buatier de Mongeot, "Evidence of anomalous refraction of self-assembled curved gold nanowires", Appl. Phys. Lett. 100, 251109 (2012). CrossRef A. Belardini, F. Pannone, G. Leahu, M.C. Larciprete, M. Centini, C. Sibilia, C. Martella, M. Giordano, D. Chiappe, F. Buatier de Mongeot, "Asymmetric transmission and anomalous refraction in metal nanowires metasurface", J. Europ. Opt. Soc. Rap. Public. 7, 12051 (2012). CrossRef A. Belardini, C. Sibilia, Optoelectron. Adv. Mater. ? Rapid Commun. 7, 184 (2013). DirectLink A. Sinibaldi, N. Danz, E. Descrovi, P. Munzert, U. Schulz, F. Sonntagd, L. Dominici, F. Michelotti, "Direct comparison of the performance of Bloch surface wave and surface plasmon polariton sensors", Sensors and Actuators B 174, 292?298 (2012). CrossRef A. Belardini, A. Bosco, G. Leahu, M. Centini, E. Fazio, C. Sibilia, M. Bertolotti, S. Zhukovsky, S.V. Gaponenko, "Femtosecond pulses chirping compensation by using one-dimensional compact multiple-defect photonic crystals", Appl. Phys. Lett. 89, 031111 (2006). CrossRef A. Belardini, M.C. Larciprete, M. Centini, E. Fazio, C. Sibilia, D. Chiappe, C. Martella, A. Toma, M. Giordano, F. Buatier de Mongeot, "Circular Dichroism in the Optical Second-Harmonic Emission of Curved Gold Metal Nanowires", Phys. Rev. Lett. 107, 257401 (2011). CrossRef A. Belardini, M.C. Larciprete, M. Centini, E. Fazio, C. Sibilia, M. Bertolotti, A. Toma, D. Chiappe, F. Buatier de Mongeot, "Tailored second harmonic generation from self-organized metal nano-wires arrays", Opt. Expr. 17, 3603 (2009). CrossRef

IO N Exploring new physical-chemical properties of atomically thin graphitic materials is retaining a booming interest and it is expected to have a tremendous impact on the development of future nanoelectronic devices. So far, the enormous consideration for graphene [ 1 , 2 ] has overshadowed other two dimensional (2D) counterparts which may overcome the intrinsic limitations of graphene as active material. Indeed, despite the recent advances either in graphene bandgap opening [ 3–5 ] or integration in ad hoc device structures, [ 6 , 7 ] the zero-gap character of free standing graphene poses a severe drawback for an electric fi eld modulation suitable to graphene based logic devices. A strong effort is currently made to provide theoretical and experimental evidence of stable graphene-like nanolattices of the other group-IV semiconductors, the so called silicene and germanene, [ 8–11 ] which might take benefi t from being naturally compatible with the Si technology and from an intrinsically higher spin orbit coupling. Unlike graphene, the spontaneous formation of silicene is not expected to be energetically favorable because the sp 3 hybridization of Si atoms is more stable than the sp 2 one. However, a graphene-like form of silicene has been theoretically predicted [ 8 , 9 , 12 ] and, in just a few years, experimental investigations have moved up this fascinating hypothesis to concrete evidence. Recent experiments [ 13 , 14 ] report on the epitaxial growth of silicene on Ag(111) substrates with a non-trivial surface arrangement and relevant electronic features such as a linear electronic dispersion at the K points and an estimated Fermi velocity v F = 1.3 × 10 6 ms − 1 . [ 13 ]

Quantitative structure–toxicity relationships were developed for the prediction of toxicity to Vibrio fischeri using the CODESSA treatment. A four-parameter correlation was found for a class of ionic liquids based on halide. All the descriptors utilized are calculated only from the structures of the molecules, which makes it possible to predict unavailable or unknown ILs, in gas phase and in water (PCM treatment). Satisfactory correlations with the same descriptors were found for both cases but the employment of descriptors calculated in solvent assure a better correlation and a bigger reliability on the foresight.

A study of the reaction of thioanisole with singlet oxygen in different ionic liquid-acetonitrile binary mixtures has shown that ILs are able to accelerate the thioanisole sulfoxidation when used as additives. With imidazolium ILs, the maximum efficiency is reached at x(IL) ∼ 0.1-0.2, whereas for the pyrrolidinium IL a plateau is reached. These results are discussed in terms of the ILs' tendency to form ionic aggregates and of differences in sulfoxidation reaction mechanism.