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In this work, we compare nanoaggregation driven by pH-induced micellization (PIM) and by the standard solvent displacement (SD) method on a series of pH-, light-, and thermosensitive amphiphilic block copolymers. Specifically, we investigate poly(HIABMA)

The main purpose of the present work is to analyze a series of Ag nanoparticles (NPs) with different size or ligand functionalization by using X-ray photoelectron spectroscopy (XPS) and to identify the differences in the band-shape and energy peak position of photoemission spectra due to the particle dimension. A transmission electron microscopy characterization was performed, to verify the consistency of the results. Three types of samples were prepared starting from AgNO3 water solution and adding different capping agents. In the first two cases, the formation of NPs was promoted by the reduction of silver ions Ag+1 to metallic Ag-0 through the addition of sodium borohydride, whereas in the last case, it was triggered by the exposure to UV light. Depending on the size of the NPs, a different physical behavior can be recognized. NPs with diameter of about 5 nm are characterized by the phenomenon of localized surface plasmon resonance (LSPR). The other type of samples having a diameter of about 1.5 nm presents discrete energy levels instead of electronic bands, and in this case, a typical fluorescence phenomenon can be observed. In the latter case, we can refer to such systems as nanoclusters. The XPS analyses were focused on the Ag 3D spectra looking for the possible shifts of the Ag doublet as a function of the particles size. The ultraviolet photoelectron spectroscopy with He II source was used for the investigation of possible changes in the valence band.

Treatment of pulmonary infections caused by Mycobacterium abscessus are extremely difficult to treat, as this species is naturally resistant to many common antibiotics. Liposomes are vesicular nanocarriers suitable for hydrophilic and lipophilic drug loading, able to deliver drugs to the target site, and successfully used in different pharmaceutical applications. Moreover, liposomes are biocompatible, biodegradable and nontoxic vesicles and nebulized liposomes are efficient in targeting antibacterial agents to macrophages. The present aim was to formulate rifampicin-loaded liposomes (RIF–Lipo) for lung delivery, in order to increase the local concentration of the antibiotic. Unilamellar liposomal vesicles composed of anionic DPPG mixed with HSPC for rifampicin delivery were designed, prepared, and characterized. Samples were prepared by using the thin-film hydration method. RIF–Lipo and unloaded liposomes were characterized in terms of size, ζ-potential, bilayer features, stability and in different biological media. Rifampicin’s entrapment efficiency and release were also evaluated. Finally, biological activity of RIF-loaded liposomes in Mycobacterium abscessus-infected macrophages was investigated. The results show that RIF-lipo induce a significantly better reduction of intracellular Mycobacterium abscessus viability than the treatment with free drug. Liposome formulation of rifampicin may represent a valuable strategy to enhance the biological activity of the drug against intracellular mycobacteria.

In this chapter we describe: (1) the procedure for the synthesis of four single chain bolaamphiphiles, displaying chains of 12, 16, 20 and 30 methylene units and triphenylphosphonium moieties as headgroups (TPP1-TPP4); (2) the methods used to characterize TPP1-TPP4 spontaneous aggregation in aqueous solution. We illustrate the determination of Krafft point and cac by conductivity measurements and the procedures used to investigate dimensions, morphology, and stability by dynamic and dielectrophoretic laser light scattering, dialysis, transmission electron microscopy, and Raman spectroscopy measurements.

There is a growing interest in therapeutically targeting the inflammatory response that underlies age-related chronic diseases including obesity and type 2 diabetes. Through integrative small RNA sequencing, we show the presence of conserved plant miR159a and miR156c in dried nuts having high complementarity with the mammalian TNF receptor superfamily member 1a (Tnfrsf1a) transcript. We detected both miR159a and miR156c in exosome-like nut nanovesicles (NVs) and demonstrated that such NVs reduce Tnfrsf1a protein and dampen TNF-α signaling pathway in adipocytes. Synthetic single-stranded microRNAs (ss-miRs) modified with 2′-O-methyl group function as miR mimics. In plants, this modification naturally occurs on nearly all small RNAs. 2′-O-methylated ss-miR mimics for miR156c and miR159a decreased Tnfrsf1a protein and inflammatory markers in hypertrophic as well as TNF-α-treated adipocytes and macrophages. miR156c and miR159a mimics effectively suppress inflammation in mice, highlighting a potential role of plant miR-based, single-stranded oligonucleotides in treating inflammatory-associated metabolic diseases., Aquilano et al. identify conserved plant miR159a and miR156c in dried nuts and show that these miRNAs target TNF receptor superfamily member 1a to suppress TNF-α-mediated inflammation. This study highlights the potential of plant miR-based oligonucleotides as a therapeutic option to treat metabolic diseases hallmarked by inflammation.

Structural and microstructural investigations of Pd-doped lanthanum strontium ferrite with stoichiometry La0.6Sr0.4Fe0.95Pd0.05O3-? (LSFPd) were carried out under oxidizing and reducing conditions using XRD, Rietveld refinement, XPS, SEM, and TEM analyses. LSFPd exhibited a smart behaviour with a reversible redox structural transformation occurring upon switching from air to hydrogen and then back to air. Exsolution of nanometric metal particles was observed after reduction, and reincorporation of metal cations onto the perovskite structure was confirmed after reoxidation. The electrochemical performances were evaluated on electrolyte supported cells using LSFPd as symmetric electrodes. The self-regenerating redox process largely improved the anodic performance of LSFPd-based SOFCs because it mitigates the coarsening of metallic electrocatalysts at high temperature promoting a redox stable behaviour. Fuel cell tests revealed promising performance in terms of maximum power output and redox stability.

Hypothesis Bolaamphiphiles are characterized by wide polymorphism of their aggregates, due to the connection of the headgroups that renders their investigation very intriguing in several technological applications. Some bolaamphiphiles displaying the triphenylphosphonium motif (TPP-bolaamphiphiles) were previously explored for their ability in crossing the mitochondrial membranes but their colloidal features, which are crucial for the potential development of an effective drug delivery system, were never investigated. Experiments Single chain TPP-bolaamphiphiles, featuring chains of 12, 16, 20 and 30 methylene units, were synthesized and their aggregation features (Krafft point, cac, dimensions, morphology, stability) were investigated by conductivity, dialysis, transmission electron microscopy, Raman spectroscopy, dynamic and dielectrophoretic laser light scattering measurements. Findings All the TPP-bolaamphiphiles spontaneously self-assemble into vesicles, independently of the chain length. The bolaamphipile with the longest chain forms monodispersed vesicles whereas for the other bolaamphiphiles two distinct populations of vesicles are observed. All vesicles are not equilibrium systems, in particular vesicles formed by the bolaamphiphiles featuring 20 and 30 methylene units result notably stable to dilution thanks to both the tightening of molecular packing at increasing chain length and the progressive reduction of the monomer percentage in U-shaped conformation. These features make these TPP-bolaamphiphiles very attractive as minor components for the development of novel mitochondriotropic liposomes.

Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.

PNIPAm microgels synthesized via free radical polymerization (FRP) are often considered as neutral colloids in aqueous media, although it is well known, since the pioneering work of Pelton and coworkers [Langmuir 1989, 5, 816-818], that the vanishing electrophoretic mobility characterizing swollen microgels largely increases above the lower critical solution temperature (LCST) of PNIPAm, at which microgels partially collapse. The presence of an electric charge has been attributed to the ionic initiators that are employed when FRP is performed in water and that stay anchored to microgel particles. Combining dynamic light scattering (DLS), electrophoresis, transmission electron microscopy (TEM) and atomic force microscopy (AFM) experiments, we show that collapsed ionic PNIPAm microgels undergo large mobility reversal and reentrant condensation when they are co-suspended with oppositely charged polyelectrolytes (PE) or nanoparticles (NP), while their stability remains unaffected by PE or NP addition at lower temperatures, where microgels are swollen and their charge density is low. Our results highlight a somehow double-faced electrostatic behavior of PNIPAm microgels due to their tunable charge density: they behave as quasi-neutral colloids at temperature below LCST, while they strongly interact with oppositely charged species when they are in their collapsed state. The very similar phenomenology encountered when microgels are surrounded by polylysine chains and silica nanoparticles points to the general character of this twofold behavior of PNIPAm-based colloids in water., 22 pages, 13 figures

The growing demand for innovative means in biomedical, therapeutic and diagnostic sciences has led to the development of nanomedicine. In this context, naturally occurring tubular nanostructures composed of rolled sheets of alumino-silicates, known as halloysite nanotubes, have found wide application. Halloysite nanotubes indeed have surface properties that favor the selective loading of biomolecules. Here, we present the first, to our knowledge, structural study of DNA-decorated halloysite nanotubes, carried out with nanometric spatially-resolved infrared spectroscopy. Single nanotube absorption measurements indicate a partial covering of halloysite by DNA molecules, which show significant structural modifications taking place upon loading. The present study highlights the constraints for the use of nanostructured clays as DNA carriers and demonstrates the power of super-resolved infrared spectroscopy as an effective and versatile tool for the evaluation of immobilization processes in the context of drug delivery and gene transfer.

We have realized a 3D substrate for surface-enhanced Raman scattering (SERS) sensor with DELIL (Double Exposure Laser Interference Lithography) technique and silver nanoparticles (Ag-NPs) functionalized with an appropriate aptamer. The 3D substrates were obtained by means of soft mold technique in thin layer of sol-gel Ti/TMSPM on silicon substrate using intermediate stamp fabricated in a photosensitive material. The stamp was in turn produced with a Lloyd's mirror set up by means of double exposition (Ar+ laser at 364 nm, 23 mW) of a photopolymerizable thin film at two mutually orthogonal orientation.The obtained 3D gratings have regular cross-weave texture with holes and pillars. The Ag-NPs were deposited by drop-casting on the 3D substrates and they arranged themselves inside the holes. This controlled Ag-NPs distribution allows the system to be a potential candidate for a good SERS sensor. The easy replication of the 3D substrates from a single stamp makes this technique attractive for applications in analytic and environmental fields.

In this chapter we describe: (1) the procedure for the synthesis of four single chain bolaamphiphiles, displaying chains of 12, 16, 20 and 30 methylene units and triphenylphosphonium moieties as headgroups (TPP1-TPP4); (2) the methods used to characterize TPP1-TPP4 spontaneous aggregation in aqueous solution. We illustrate the determination of Krafft point and cac by conductivity measurements and the procedures used to investigate dimensions, morphology, and stability by dynamic and dielectrophoretic laser light scattering, dialysis, transmission electron microscopy, and Raman spectroscopy measurements.

Intermittency of renewable energy sources can be profitably faced using efficient energy storage systems. Reversible solid oxide cells (RSOCs) able to operate with carbon-containing species are likely among the most appealing choices. Energy can be obtained by natural gas and/or biogas (SOFC mode), with useful recovery of CO2 in the exhausts. Besides, if the electrode is also active towards CO2 electrolysis (SOEC mode), CO2 is reduced to CO and O2. In this work a composite material with in-situ formed Ni-Fe alloy catalyst consisting of La1.2Sr0.8Fe0.6Mn0.4O4 Ruddlesden-Popper perovskite and Ni-Ce0.85Sm0.15O2-δ fluorite was developed as a multi-functional fuel-electrode for RSOCs. The composite electrode was tested in SOFC mode as anode for hydrogen, dry methane and carbon monoxide oxidation and showed power density outputs of 657, 668 and 527 mW/cm2 at 850 °C, respectively, together with redox stability and coking tolerance for over 120 h. In SOEC mode, it was tested as cathode and delivered 2.66 A/cm2 at 2 V in a 95:5 CO2:CO mixture, retaining a current density of 1 A/cm2 for more than 40 h.

Dynamic Light Scattering (DLS), Small Angle X-ray Scattering (SAXS) and Transmission Electron Microscopy (TEM) are physical techniques widely employed to characterize the morphology and the structure of vesicles such as liposomes or human extracellular vesicles (exosomes). Bacterial extracellular vesicles are similar in size to human exosomes, although their function and membrane properties have not been elucidated in such detail as in the case of exosomes. Here, we applied the above cited techniques, in synergy with the thermotropic characterization of the vesicles lipid membrane using a turbidimetric technique to the study of vesicles produced by Gram-negative bacteria (Outer Membrane Vesicles, OMVs) grown at different temperatures. This study demonstrated that our combined approach is useful to discriminate vesicles of different origin or coming from bacteria cultured under different experimental conditions. We envisage that in a near future the techniques employed in our work will be further implemented to discriminate complex mixtures of bacterial vesicles, thus showing great promises for biomedical or diagnostic applications.

Amphipathic peptides are attractive building blocks for the preparation of self-assembling, bio-inspired and stimuli responsive nano-materials with pharmaceutical interest. The bioavailability of these materials can be improved with the insertion of D amino acid residues to avoid fast proteolysis in vivo. With this knowledge, a new lauroyl peptide consisting of a sequence of glycine, glycine, D-serine, and D-lysine was designed. In spite of its simple sequence, this lipopeptide self-assembles into spherical micelles at acid pH, when the peptide moiety adopts disordered conformations. The self-aggregates reshape towards fibers at basic pH following the conformational transition of the peptide region from random coil to β-sheet. Finally, hydrogels are achieved at basic pH and higher concentrations. The transition from random coil to β-sheet conformation of the peptide headgroup obtained by increasing pH was monitored by circular dichroism and vibrational spectroscopy. A structural analysis, performed by combining dynamic light scattering, small angle X-ray scattering, transmission electron microscopy and molecular dynamic simulations, demonstrated that the transition allows the self-assemblies to remodel from spherical micelles to rod-like shapes, to long fibers with rectangular cross section and a head-tail-tail-head structure. The viscoelastic behavior of the hydrogels formed at the highest pH was investigated by rheology measurements.

Noncovalent DNA functionalization is one of the most used routes for the easy dispersion of carbon nanotubes (CNTs) yielding DNA-CNTs complexes with promising applications. Definition of the structure of adsorbed DNA is crucial, but the organization of polymer at the carbon interface is far from being understood. In comparison to single-walled nanotubes, not much effort has been devoted to assessing the structure of the adsorbed DNA on multiwalled carbon nanotubes (MWCNTs), where their metallic nature, large size, and polydispersity represent serious obstacles for both experimental and theoretical studies. As a contribution to fill this lack in these aspects, we investigated DNA-MWCNT complexes by dielectric spectroscopy (DS) which is sensitive to even small changes in the charge distribution at charged interfaces and was largely employed in studying the electric and conformational properties of polyelectrolytes, such as DNA, in aqueous solutions and at interfaces. The dielectric relaxation in the MHz range is the signature of DNA adsorption on CNTs and sheds light on its conformational properties. A detailed analysis of the conductivity of the DNA-MWCNT suspensions unequivocally proves that DNA is adsorbed in a single-stranded conformation while excess DNA reassociates without interfering with the stability of the complexes.

The catalytic conversion of carbon dioxide to synthetic CH4 was studied on five Ni/YSZ samples, with the same nickel loading (10 wt%) but different Ni particle size. The catalysts, prepared by different methods, were characterized combining morphological (BET, TEM), structural (XRD, in-operando XAS), electronic (XPS, in-operando XANES) analysis and H2-TPR experiments. The results showed that catalytic activity and CH4 selectivity depended on size and morphology of Ni particles, and that type and amount of deposited carbon strongly depended on Ni0 morphology. The kinetic measurements revealed that both H2 and CO2 reactants were activated on Ni sites, and that YSZ support was not directly involved in the reaction mechanism. The most efficient catalyst was that prepared by wet impregnation with Ni(EDTA)2− complex due to the high Ni0 dispersion.This catalyst showed low amount of carbon and remarkable stability over time on stream. In-operando XAS showed that it did not undergo deactivation by Ni0 → Ni2+ oxidation using high CO2 concentration, thus it is applicable in dynamic conditions like those typical in the energy storage from renewable sources process.

Antonella Celluzzi,1,* Alessandro Paolini,1,* Valentina D’Oria,1 Roberta Risoluti,2 Stefano Materazzi,2 Marco Pezzullo,1 Stefano Casciardi,3 Simona Sennato,4 Federico Bordi,4 Andrea Masotti1 1Bambino Gesù Children’s Hospital, IRCCS, Research Laboratories, 2Department of Chemistry, Sapienza University of Rome, 3Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, National Institution for Insurance Against Accidents at Work (INAIL Research), Monte Porzio Catone, 4CNR-ISC UOS Roma, Department of Physics, Sapienza University of Rome, Roma, Italy *These authors contributed equally to this work Abstract: Recent findings in nanomedicine have revealed that carbon nanotubes (CNTs) can be used as potential drug carriers, therapeutic agents and diagnostics tools. Moreover, due to their ability to cross cellular membranes, their nanosize dimension, high surface area and relatively good biocompatibility, CNTs have also been employed as a novel gene delivery vector system. In our previous work, we functionalized CNTs with two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM). These compounds have low cytotoxicity, ability to conjugate microRNAs (such as miR-503) and, at the same time, transfect efficiently endothelial cells. The parameters contributing to the good efficiency of transfection that we observed were not investigated in detail. In fact, the diameter and length of CNTs are important parameters to be taken into account when evaluating the effects on drug delivery efficiency. In order to investigate the biophysical and biological contributions of polymer-coated CNTs in delivery of miRNAs to human cells, we decided to investigate three different preparations, characterized by different dimensions and aspect ratios. In particular, we took into account very small CNTs, a suspension of CNTs starting from the commercial product and a 2D material based on CNTs (ie, buckypapers [BPs]) to examine the transfection efficiency of a rigid scaffold. In conclusion, we extensively investigated the biophysical and biological contributions of polyamine-coated CNTs and bidimensional BPs in the delivery of miRNAs to human cells, in order to optimize the transfection efficiency of these compounds to be employed as efficient drug delivery vectors in biomedical applications. Keywords: carbon nanotubes, buckypapers, polyamines, cytotoxicity, cell transfection&nbsp

A method is described for the quantification of the sp2, sp3 and intermediate hybridizations in several carbon (C) material samples. Electron energy-loss near-edge spectra were acquired using fast electrons (120 keV) in an electron microscope in nanobeam configuration under the so-called ”magic-angle” condition, and were analysed to extract the sp2 and sp3 fractions, and identify the possible mixed sp2+e hybridizations. The method consists in projecting the unknown spectra on a basis made up of pure sp2 and sp3 spectra, obtained under the same experimental conditions from graphite and diamond crystals, respectively. The residual spectra contain information about the intermediate hybridizations sp2+e occurring in the samples. The method was successfully tested on “ab initio” numerically generated spectra relative to amorphous C materials. Finally, it was applied to actual C amorphous and pyrolytic samples, and results were compared to those obtained by the most commonly used, conventional ”three-Gaussian” method. The combined application of electron diffraction and spectroscopy, in the nanobeam configuration, yielded useful information about the atomic and electronic structure from very small volumes of the unknown C material.

Metal nanoclusters (MNCs) are small aggregates of metal atoms with a mean diameter up to 2 nm, that when excited by electromagnetic radiation of suitable energy present an intense florescence. This optical property can be exploited in many fields such as bioimaging, drug delivery and optical sensing in environmental monitoring. In the present work, we synthesized silver nanoclusters (AgNCs) in water starting from AgNO3 and exploiting poly (methacrylic acid) (PMAA) as capping agent. The reduction of the silver ions Ag(I) to Ag(0) was promoted by the exposition of the solution to UV light radiation for 6 minutes. We studied the UV-Vis absorption and the fluorescence spectra for different pH values. The morphological characterization of the solution was accomplished by Transmission Electron Microscopy (TEM) and the statistical analysis showed that the mean diameter of the AgNCs was around 2 nm for the solution at pH = 4 which presented also the strongest fluorescence. Moreover, we studied the time stability of the absorption and fluorescence spectra. AgNCs stored in the dark at 4 °C were stable for more than 60 days. A possible application of the synthesized AgNCs deals with water monitoring by optical sensing based on the change of the fluorescence property in presence of heavy metal ions. Preliminary investigations show a high sensitivity to Pb(II) ions.Metal nanoclusters (MNCs) are small aggregates of metal atoms with a mean diameter up to 2 nm, that when excited by electromagnetic radiation of suitable energy present an intense florescence. This optical property can be exploited in many fields such as bioimaging, drug delivery and optical sensing in environmental monitoring. In the present work, we synthesized silver nanoclusters (AgNCs) in water starting from AgNO3 and exploiting poly (methacrylic acid) (PMAA) as capping agent. The reduction of the silver ions Ag(I) to Ag(0) was promoted by the exposition of the solution to UV light radiation for 6 minutes. We studied the UV-Vis absorption and the fluorescence spectra for different pH values. The morphological characterization of the solution was accomplished by Transmission Electron Microscopy (TEM) and the statistical analysis showed that the mean diameter of the AgNCs was around 2 nm for the solution at pH = 4 which presented also the strongest fluorescence. Moreover, we studied the time stability ...

Hypothesis: The peculiar swelling behaviour of poly(N-isopropylacrylamide) (PNIPAM)-based responsive microgels provides the possibility to tune both softness and volume fraction with temperature, making these systems of great interest for technological applications and theoretical implications. Their intriguing phase diagram can be even more complex if poly(acrylic acid) (PAAc) is interpenetrated within PNIPAM network to form Interpenetrating Polymer Network (IPN) microgels that exhibit an additional pH-sensitivity. The effect of the PAAc/PNIPAM polymeric ratio on both swelling capability and dynamics is still matter of investigation. Experiments: Here we investigate the role of PAAc in the behaviour of IPN microgels across the volume phase transition through dynamic light scattering (DLS), transmission electron microscopy (TEM) and electrophoretic measurements as a function of microgel concentration and pH. Findings: Our results highlight that aggregation is favored at increasing weight concentration, PAAc content and pH and that a crossover PAAc content C*_{PAAc} exists above which the ionic charges on the microgel become relevant. Moreover we show that the softness of IPN microgels can be tuned ad hoc by changing the PAAc/PNIPAM ratio. These findings provide new insights into the possibility to control experimentally aggregation properties, charge and softness of IPN microgels by varying PAAc content., Comment: preprint version

Preparation and characterization of a pH and thermosensitive linear l,d -octapeptide-poly(dimethylamino ethyl methacrylate) (( l -Val- d -Val)4-PDMAEMA) conjugate is reported. The hydrophobic uncharged linear ( l -Val- d -Val)4 octapeptide was designed to self-assemble in nanotubes by exploiting the tubular self-assembling properties of linear peptides with regularly alternating enantiomeric sequences. pH and thermosensitive PDMAEMA was obtained by atom transfer radical polymerization (ATRP). The conjugate was prepared by click-chemistry on the solid phase synthetized peptide. Because of the strong interactions between the peptide moieties, long single channel nanotubes (0.2–1.5 μm) are formed also at acidic pH with the fully charged polymer. At 25 °C and basic pH the size of the nanotubes did not change significantly. In basic conditions and temperature above the PDMAEMA lower critical solution temperature (LCST) a significant increase of the length of the nanotubes up to several micrometers is observed. The size is retained for several days after cooling back to room temperature. Sonication significantly reduces the nanotube length (0.2–0.5 μm) forming low polydisperse nanotubes. The elongation of the nanotubes is fully reversible by restoring acidic pH. This is the first example, to our knowledge, of thermosensitive peptide-polymer single channel nanotubes with length that can be varied from hundreds of nanometers to several micrometers.

The controversy about the adsorption of DNA onto/into halloysite is mainly due to the lacking of an absorption isotherm. As in other colloidal clays systems, experimental difficulties in separating excess non-adsorbed DNA from DNA–halloysite hybrids hinder the reliable determination of the adsorption. According to literature, sedimentation of nanoparticles in a colloidal system is affected by a complex interplay of local density, viscosity and inter-particle interactions. In this context, an increase in the ionic strength can enhance sedimentation by reducing inter-particle repulsions. In this work, we propose an improved centrifugation procedure by fine tuning of the ionic strength An effective strategy for sedimentation of DNA–halloysite hybrids is defined and discussed. Adsorption isotherms are obtained for chromosomal linear DNA in both native or denatured conditions. Importantly, DNA is adsorbed at the outer surface of halloysite despite electrostatic repulsive interactions. The proposed method will boost investigations on the adsorption of a variety nucleic acids for gene delivery formulation or the mechanistic understanding of biological impact of halloysite nanotubes and other novel nanomaterials.

Production of propellant for the return to Earth from in-situ resources allows not transporting the return fuel in space explorations. CO 2 from Martian atmosphere may react with H2 to produce methane and water by Sabatier reaction. The activity of Ni (10 wt%) supported on Y 2 O 3 -ZrO 2 , by different preparation methods, was compared. Structural characterization by XRD, TPR and TEM, evidenced that catalytic performances for CO 2 methanation mainly depended on the Ni°particle size and morphology. In particular, the catalyst prepared by wet impregnation with Ni(EDTA)−2 complex, having high nickel dispersion and strong Ni-support interaction, showed remarkable activity, selectivity and stability over time on stream using stoichiometric flow (CO 2 :H 2 = 1:4), appearing like a reliable catalyst for Sabatier process.

Ophiolitic rocks cropping on Calabria territory, southern Italy, can hold asbestiform minerals potentially harmful for human health. The aim of this work was to detect the fibrous phases of ophiolites along the Coastal Chain of northern Calabria and southern part of the Sila massif. Above 220 massive samples were collected in the study areas and analyzed using optical and electron microscopy, X-ray diffractometry, and Fourier transform infra-red spectrometry. The main fibrous constituent belonged to tremolite-actinolite series followed by fibrous antigorite that becomes more abundant in the samples collected in Reventino Mount surroundings. Results highlighted that serpentinites samples mainly consisted of antigorite and minor chrysotile. Samples collected along the coastal chain of northern Calabria did not hold fibrous materials. The results will be useful for Italian natural occurrences of asbestos (NOA) mapping in order to avoid an unintentional exposition by human activity or weathering proce...

We investigated the complexation of thermoresponsive anionic poly(N-isopropylacrylamide) (PNiPAM) microgels and cationic $\epsilon$-polylysine ($\epsilon$-PLL) chains. By combining electrophoresis, light scattering, transmission electron microscopy (TEM) and dielectric spectroscopy (DS) we studied the adsorption of $\epsilon$-PLL onto the microgel networks and its effect on the stability of the suspensions. We show that the volume phase transition (VPT) of the microgels triggers a large polyion adsorption. Two interesting phenomena with unique features occur: a temperature-dependent microgel overcharging and a complex reentrant condensation. The latter may occur at fixed polyion concentration, when temperature is raised above the VPT of microgels, or by increasing the number density of polycations at fixed temperature. TEM and DS measurements unambiguously show that short PLL chains adsorb onto microgels and act as electrostatic glue above the VPT. By performing thermal cycles, we further show that polyion-induced clustering is a quasi-reversible process: within the time of our experiments large clusters form above the VPT and partially re-dissolve as the mixtures are cooled down. Finally we give a proof that the observed phenomenology is purely electrostatic in nature: an increase of the ionic strength gives rise to the polyion desorption from the microgel outer shell., Comment: 15 Figures

A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C60buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions. The lattice structure of such unfolded fullerene quantum dots (UFQDs) is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu2+, Pb2+and As(III) was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements and transmission electron microscope (TEM) images we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III) and the formation of precipitate with Pb2+require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.

With the expansion of the production and applications of multiwalled carbon nanotubes (MWCNTs) in several industrial and science branches, the potential adverse effects on human health have attracted attention. Numerous studies have been conducted to evaluate how chemical functionalization may affect MWCNT effects; however, controversial data have been reported, showing either increased or reduced toxicity. In particular, the impact of carboxylation on MWCNT cytotoxicity is far from being completely understood. The aim of this work was the evaluation of the modifications induced by carboxylated-MWCNTs (MWCNTs-COOH) on cell surface and the study of cell-MWCNT-COOH interactions by means of field emission scanning electron microscope (FESEM). Human pulmonary epithelial cells (A549) were incubated with MWCNTs-COOH for different exposure times and concentrations (10 μg/mL for 1, 2, 4 h; 5, 10, 20 μg/mL for 24 h). At short incubation time, MWCNTs-COOH were easily observed associated with plasma membrane and in contact with microvilli. After 24 h exposure, FESEM analysis revealed that MWCNTs-COOH induced evident changes in the cellular surface in comparison to control cells: treated cells showed blebs, holes and a depletion of the microvilli density in association with structure modifications, such as widening and/or lengthening. In particular, an increase of cells showing holes and microvilli structure alterations was observed at 20 μg/mL concentration. FESEM analysis showed nanotube agglomerates, of different sizes, entering into the cell with two different mechanisms: inward bending of the membrane followed by nanotube sinking, and nanotube internalization directly through holes. The observed morphological microvilli modifications, induced by MWCNTs-COOH, could affect epithelial functions, such as the control of surfactant production and secretion, leading to pathological conditions, such as alveolar proteinosis. More detailed studies will be, however, necessary to examine in depth the effects induced by MWCNTs-COOH and, in particular, the timing of the MWCNT-COOH-cell interaction.

The increasing use of cobalt oxide (Co3 O4 ) nanoparticles (NPs) in several applications and the suggested genotoxic potential of Co-oxide highlight the importance of evaluating Co3 O4 NPs toxicity. Cyto-genotoxic and inflammatory effects induced by Co3 O4 NPs were investigated in human alveolar (A549), and bronchial (BEAS-2B) cells exposed to 1-40 µg ml(-1) . The physicochemical properties of tested NPs were analysed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Cytotoxicity was studied to analyze cell viability (WST1 test) and membrane damage (LDH assay), direct/oxidative DNA damage was assessed by the Formamido-pyrimidine glycosylase (Fpg)-modified comet assay and inflammation by interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha (TNF-α) release (ELISA). In A549 cells, no cytotoxicity was found, whereas BEAS-2B cells showed a viability reduction at 40 µg ml(-1) and early membrane damage at 1, 5 and 40 µg ml-1. In A549 cells, direct and oxidative DNA damage at 20 and 40 µg ml(-1) were detected without any effects on cytokine release. In BEAS-2B cells, significant direct DNA damage at 40 µg ml(-1) and significant oxidative DNA damage with a peak at 5 µg ml(-1) , that was associated with increased TNF-α release at 1 µg ml(-1) after 2 h and increased IL-8 release at 20 µg ml(-1) after 24 h, were detected. The findings show in the transformed alveolar cells no cytotoxicity and genotoxic/oxidative effects at 20 and 40 µg ml(-1) . In normal bronchial cells, moderate cytotoxicity, direct DNA damage only at the highest concentration and significant oxidative-inflammatory effects at lower concentrations were detected. The findings confirm the genotoxic-oxidative potential of Co3 O4 NPs and show greater sensitivity of BEAS-2B cells to cytotoxic and oxidative-inflammatory effects suggesting the use of different cell lines and multiple end-points to elucidate Co3 O4 NPs toxicity.

The potential health effects of functionalized MWCNTs, used in biomedical applications as considered more biocompatibile than pristine MWCNTs, are not well defined. Chemical functionalization used to increase solubility and dispersion of CNTs, allows to implement their possible applications, but could modify their toxicity. We investigated and compared cytotoxic, genotoxic/oxidative and inflammatory effects of commercial pristine and -OH and -COOH functionalized MWCNTs on human bronchial BEAS-2B cells. The aim was to identify an in vitro experimental model that uses different and complementary end-points to study potential CNT toxicity and to evaluate the role of functionalization on the induced effects. Cells were exposed to 1-40 μg/mL of each CNT for 24 h. We evaluated: cell viability by WST1; membrane damage by LDH assay; direct/oxidative DNA damage by Fpg-comet assay; IL-6, IL-8 and TNFα release by ELISA. We found a statistically significant reduction of cell viability after exposure to functionalized MWCNTs, particularly MWCNT-COOH at 20 and 40 μg/mL. Membrane damage was induced only by pristine and MWCNT–COOH at 20 and 40 μg/mL. Concentration-dependent increase of direct DNA damage was found for all CNTs, particularly for the functionalized MWCNTs. A moderate induction of oxidative DNA damage was observed for OH-functionalized MWCNTs. Only pristine MWCNTs induced significant IL-8 release at the highest concentrations. The results indicate different toxicity mechanisms for tested MWCNTs on bronchial cells with higher cyto-genotoxicity for functionalized MWCNTs, no membrane damage and induction of oxidative DNA damage for MWCNT-OH, and inflammatory response for pristine MWCNTs. The findings show the suitability of our experimental model to study CNT toxicity and to evaluate the influence of functionalization on induced effects.

We report on synthesis of silver nanoparticles (AgNPs) capped with specific thiol suitable to detect heavy metal ions in water. The sensing mechanism is based on a change of an optical properties of the silver colloids, namely the surface plasmon resonance (SPR) when small amounts of contaminants are present in solution. We detected a specific sensitivity to nickel ions and we investigated the interaction of the AgNPs with Ni2+ in the concentration range of 0.5–2.0 ppm.

A series of Ni (10 wt %) supported on commercial yttrium stabilized zirconia (YSZ) catalysts have been prepared by different methods to evaluate the effect of Ni0 particle size on CO2 methanation activity. The reducibility and metal-support interaction were analyzed by H2-temperature programmed reduction (TPR) and in-situ x-ray absorption spectroscopy (XAS). The particle size and morphology were analyzed by TEM. A correlation of the catalytic activity with Ni0 particle size and metal-support interaction was found. The catalyst stability during time of stream (TOS) and under CO2 stream was performed by in-situ XAS. Apparent activation energy and reaction orders are determined for the most performing catalyst.

The toxicity of titanium dioxide nanoparticles (TiO2-NPs), used in several applications, seems to be influenced by their specific physicochemical characteristics. Cyto-genotoxic and inflammatory effects induced by a mixture of 79% anatase/21% rutile TiO2-NPs were investigated in human alveolar (A549) and bronchial (BEAS-2B) cells exposed to 1–40 µg ml–1 30 min, 2 and 24 h to assess potential pulmonary toxicity. The specific physicochemical properties such as crystallinity, NP size and shape, agglomerate size, surface charge and specific surface area (SSA) were analysed. Cytotoxic effects were studied by evaluating cell viability using the WST1 assay and membrane damage using LDH analysis. Direct/oxidative DNA damage was assessed by the Fpg-comet assay and the inflammatory potential was evaluated as interleukin (IL)-6, IL-8 and tumour necrosis factor (TNF)-α release by enzyme-linked immunosorbant assay (ELISA). In A549 cells no significant viability reduction and moderate membrane damage, only at the highest concentration, were detected, whereas BEAS-2B cells showed a significant viability reduction and early membrane damage starting from 10 µg ml–1. Direct/oxidative DNA damage at 40 µg ml–1 and increased IL-6 release at 5 µg ml–1 were found only in A549 cells after 2 h. The secretion of pro-inflammatory cytokine IL-6, involved in the early acute inflammatory response, and oxidative DNA damage indicate the promotion of early and transient oxidative-inflammatory effects of tested TiO2-NPs on human alveolar cells. The findings show a higher susceptibility of normal bronchial cells to cytotoxic effects and higher responsiveness of transformed alveolar cells to genotoxic, oxidative and early inflammatory effects induced by tested TiO2-NPs. This different cell behaviour after TiO2-NPs exposure suggests the use of both cell lines and multiple end-points to elucidate NP toxicity on the respiratory system. Copyright © 2014 John Wiley & Sons, Ltd.

The design of biocompatible polyelectrolyte complexes is a promising strategy for in vivo delivery of biologically active macromolecules. Particularly, the condensation of DNA by polycations received considerable attention for its potential in gene delivery applications, where the development of safe and effective non-viral vectors remains a central challenge. Among polymeric polycations, Chitosan has recently emerged as a very interesting material for these applications. In this study, we compare the observed aggregation behavior of Chitosan-DNA complexes with the predictions of existing models for the complexation of oppositely charged polyelectrolytes. By using different and complementary microscopy approaches (AFM, FESEM and TEM), light scattering and electrophoretic mobility techniques, we characterized the structures of the complexes formed at different charge ratios and Chitosan molecular weight. In good agreement with theoretical predictions, a reentrant condensation, accompanied by charge inversion, is clearly observed as the polycation/DNA charge ratio is increased. In fact, the aggregates reach their maximum size in correspondence of a value of the charge ratio where their measured net charge inverts its sign. This value does not correspond to the stoichiometric 1:1 charge ratio, but is inversely correlated with the polycation length. Distinctive "tadpole-like" aggregates are observed in excess polycation, while only globular aggregates are found in excess DNA. Close to the isoelectric point, elongated fiber-like structures appear. Within the framework of the models discussed, different apparently uncorrelated observations reported in the literature find a systematic interpretation. These results suggest that these models are useful tools to guide the design of new and more efficient polycation-based vectors for a more effective delivery of genetic material. © 2013 Elsevier B.V.

Functionalized MWCNTs are used in many commercial and biomedical applications, but their potential health effects are not well defined. We investigated and compared cytotoxic, genotoxic/oxidative, and inflammatory effects of pristine and carboxyl MWCNTs exposing human respiratory (A549 and BEAS-2B) cells to 1–40 μg/mL of CNTs for 24 h. Both MWCNTs induced low viability reduction (by WST1 assay) in A549 cells and only MWCNTs-COOH caused high viability reduction in BEAS-2B cells reaching 28.5% viability at 40 μg/mL. Both CNTs induced membrane damage (by LDH assay) with higher effects in BEAS-2B cells at the highest concentrations reaching 20% cytotoxicity at 40 μg/mL. DNA damage (by Fpg-comet assay) was induced by pristine MWCNTs in A549 cells and by both MWCNTs in BEAS-2B cells reaching for MWCNTs-COOH a tail moment of 22.2 at 40 μg/mL versus 10.2 of unexposed cells. Increases of IL-6 and IL-8 release (by ELISA) were detected in A549 cells exposed to MWCNTs-COOH from 10 μg/mL while IL-8 increased in BEAS-2B cells exposed to pristine MWCNTs at 20 and 40 μg/mL. The results show higher cytogenotoxicity of MWCNTs-COOH in bronchial and of pristine MWCNTs in alveolar cells. Different inflammatory response was also found. The findings suggest the use ofin vitromodels with different end points and cells to study CNT toxicity.

In the present study, the catalytic activity of palladium oxide (PdOx) supported on ceria nanorods (CeO2-NR) for aerobic selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) was evaluated. The CeO2-NR was synthesized hydrothermally and the Pd(NO3)2 was deposited by a wet impregnation method, followed by calcination to acquire PdOx/CeO2-NR. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), Brunauer&ndash, Emmet&ndash, Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). In addition, the TPR-reduced PdOx/CeO2-NR (PdOx/CeO2-NR-Red) was studied by XRD, BET, and XPS. Characterizations showed the formation of CeO2-NR with (111) exposed plane and relatively high BET surface area. PdOx (x &gt, 1) was detected to be the major oxide species on the PdOx/CeO2-NR. The activities of the catalysts in BnOH oxidation were evaluated using air, as an environmentally friendly oxidant, and various solvents. Effects of temperature and palladium oxidation state were investigated. The PdOx/CeO2-NR showed remarkable activity when protic solvents were utilized. The best result was achieved using PdOx/CeO2-NR and boiling ethanol as solvent, leading to 93% BnOH conversion and 96% selectivity toward PhCHO. A mechanistic hypothesis for BnOH oxidation with PdOx/CeO2-NR in ethanol is presented.

A method is described for the quantification of the sp

The aim of this multidisciplinary work is to assess the potentiality of remote sensing multispectral infrared visible imaging spectrometer (MIVIS) data classified for mapping asbestos–cement roofing. In order to validate the methodology, measurement were carried out on the ground in order to later verify the results between the processed data and reality. All roofs classified as asbestos–cement were then sampled and analysed by phase contrast optical microscopy and/or scanning electron microscopy. The average classification accuracy obtained corresponds to 89.1%, and the classification accuracy of the test pixels of asbestos–cement is equal to 94.3%. Only 5.7% of pixels were misclassified. Information about the presence of asbestos–cement in the studied area has been also collected. The asbestos–cement surfaces of buildings vary from 100 to 5,000 m2, totalling to 30,800 m2, which is approximately 400,400 kg of asbestos surfaces in an area of 5.2 km2. The integration of these techniques, resulting from both MIVIS data classification and the results provided by laboratory analyses of the roofs samples, in particular from those not detected by processing MIVIS data, allowed the validation and improvement of this method, and the possibility to develop researches specifically aimed at highlighting the state of alteration of asbestos-cement surfaces. Regardless of these encouraging results, further testing in different areas is still needed in order to improve the methodology developed.