Pubblicazioni recenti in evidenza

N. Vicentini, T. Gatti, P. Salice, G. Scapin, C. Marega, F. Filippini, E. Menna

Journal: Carbon (IF: 6.337)

DOI: 10.1016/j.carbon.2015.08.094

A biocompatible porous scaffold obtained via electrospinning a nanocomposite solution of poly(L-lactic acid) and 4-methoxyphenyl functionalized multi-walled carbon nanotubes is presented here for the first time for the enhancement of neurite outgrowth. Optimization of blend preparation and deposition parameters paves the way to the obtainment of defect-free random networks of nanofibers with homogeneous diameters in the hundreds of nanometers length scale. The tailored covalent functionalization of nanotube surfaces allows a homogeneous dispersion of the nanofillers within the polymer matrix, diminishing their natural tendency to aggregate and form bundles. This results in a remarkable effect on the crystallization temperature, as evidenced through differential scanning calorimetry. Furthermore, transmission electron microscopy shows carbon nanotubes anisotropically aligned along the fiber axes, a feature believed to enhance neurite adhesion and growth. Indeed, microscopy images show neurites extension along the direction of nanofibers, highlighting the extreme relevance of scaffold morphology in engineering complex tissue environments. Furthermore, a remarkable effect on increasing the neurite outgrowth results when using the fibrous scaffold containing dispersed carbon nanotubes in comparison with an analogous one made of only polymer, providing further evidence of the key role played by carbon nanostructures in inducing neuronal differentiation.

Elisabetta Schievano, Marco Tonoli, and Federico Rastrelli

Analytical Chemistry (I.F. 6.320)
DOI: 10.1021/acs.analchem.7b03656
Publication Date (Web): November 7, 2017

The knowledge on carbohydrates composition is of great importance to determine the properties of natural matrices such as food-stuff and food ingredients. However, due to the structural similarity and the multiple isomeric forms of carbohydrates in solution, their analysis is often a complex task. Here we propose an NMR analytical procedure based on highly selective chemical shift fil-ters followed by TOCSY, which allows to acquire specific background-free signals for each sugar. The method was tested on raw honey samples dissolved in water with no other pre-treatment. Twenty two sugars typically found in honey were quantified: four monosaccharides (glucose, fructose, mannose, rhamnose), eleven disaccharides (sucrose, trehalose, turanose, maltose, maltulose, palatinose, melibiose and melezitose, isomaltose, gentiobiose nigerose and kojibiose) and seven trisaccharides (raffinose, isomalto-triose, erlose, melezitose, maltotriose, panose and 1-kestose). Satisfactory results in terms of limit of quantification (0.03 – 0.4 g/100g honey), precision (% RSD: 0.99 – 4.03), trueness (bias % 0.4 – 4.2) and recovery (97 – 104 %) were obtained. An accurate control of the instrumental temperature and of the sample pH endows an optimal chemical shift reproducibility, making the proce-dure amenable to automation and suitable to routine analysis. While validated on honey, which is one of the most complex natural matrices in terms of saccharides composition, this innovative approach can be easily transferred to other natural matrices.

Yun Luo, Björn Kirchhoff, Donato Fantauzzi, Laura Calvillo, Luis Alberto Estudillo-Wong, Gaetano Granozzi, Timo Jacob, and Nicolas Alonso-Vante

ChemSusChem 2017, DOI: 10.1002/cssc.201701822 (I.F.= 7.226)

Improving the efficiency of Pt-based oxygen reduction reaction (ORR) catalysts while also reducing costs remains an important challenge in energy research. To this end, we synthesized highly stable and active carbon-supported Mo-doped PtCu (Mo-PtCu/C) nanoparticles (NPs) from readily available precursors in a facile one-pot reaction. Mo-PtCu/C displays two- to four-fold higher ORR half-cell kinetics than reference PtCu/C and Pt/C materials – a trend which was confirmed in proof-of-concept experiments using a H2/O2 micro-laminar fuel cell. This Mo-induced activity increase mirrors observations for Mo-PtNi/C NPs and possibly suggests an emerging trend. Electrochemical accelerated stability tests revealed that dealloying is greatly reduced in Mo-PtCu/C in contrast to the binaries PtCu/C and PtMo/C. Supporting DFT studies suggest that Mo-PtCu’s exceptional stability can be attributed to oxidative resistance of Mo-doped atoms. Furthermore, our calculations revealed that oxygen can induce segregation of Mo to the catalytic surface where it effects beneficial changes to the surface’s oxygen adsorption energetics in context of the Sabatier principle. 

Pandiaraj Sekar, Laura Calvillo, Cristina Tubaro, Marco Baron, Anuj Pokle, Francesco Carraro, Alex Martucci and Stefano Agnoli

ACS Catalysis 2017, DOI: 10.1021/acscatal.7b02166 (I.F.= 10.614)

Carbon dioxide reduction into useful chemical products is a key technology to address urgent climate and energy challenges. In this study, a nanohybrid made by Co3O4 and graphene is proposed as an efficient electrocatalyst for the selective reduction of CO2 to formate at low overpotential. The comparison between samples with different metal oxide to carbon ratio and with or without doping of the graphene moiety, indicates that the most active catalyst is formed by highly dispersed and crystalline nanocubes exposing {001} oriented surfaces, whereas the nitrogen doping is critical to obtain a controlled morphology and to facilitate a topotactic transformation during electrocatalytic conditions to CoO, which results to be the true active phase. The nanohybrid made up by intermediate loading of Co3O4 supported on Nitrogen doped graphene is the most active catalyst, being able to produce 3.14 mmol of formate in 8 h at -0.95 V vs SCE with a faradic efficiency of 83% 

 

Valerio Matozzo a, Jacopo Fabrello, Luciano Masiero, Federico Ferraccioli, Livio Finos, Paolo Pastore, Iole Maria Di Gangi, Sara Bogialli

IF 5.099

Accepted 25 October 2017

DOI: https://doi.org/10.1016/j.envpol.2017.10.100

Glyphosate (GLY) is one of the most used herbicide worldwide. Considering that information concerning the impact of GLY on bivalves is scarce, in this study we evaluated for the first time the effects of environmentally realistic concentrations of GLY (10, 100 and 1000 mg/L) to the mussel Mytilus galloprovincialis. Mussels were exposed for 7, 14 and 21 days and several biomarkers were measured in haemocytes/haemolymph (total haemocyte counts, haemocyte diameter and volume, haemolymph pH, haemolymph lactate dehydrogenase activity, haemocyte lysate lysozyme and acid phosphatase activities), as well as in gills and digestive gland (antioxidant enzyme and acetylcholinesterase activities). The concentrations of GLY and its main metabolite aminomethylphosphonic acid in the experimental tanks were also measured. The MANOVA analysis demonstrated that the experimental variables considered (exposure concentration, exposure duration, and their interaction) affected significantly biomarker responses. In addition, the two-way ANOVA analysis indicated that GLY was able to affect most of the cellular parameters measured, whereas antioxidant enzyme activities resulted to be influenced moderately. Interestingly, exposure to GLY reduced significantly acetylcholinesterase activity in gills. Although preliminary, the results of this study demonstrated that GLY can affect both cellular and biochemical parameters in mussels, highlighting a potential risk for aquatic invertebrates.

Valerio Matozzo a, Jacopo Fabrello, Luciano Masiero, Federico Ferraccioli, Livio Finos, Paolo Pastore, Iole Maria Di Gangi, Sara Bogialli

IF 5.099

Accepted 25 October 2017

DOI: https://doi.org/10.1016/j.envpol.2017.10.100

Glyphosate (GLY) is one of the most used herbicide worldwide. Considering that information concerning the impact of GLY on bivalves is scarce, in this study we evaluated for the first time the effects of environmentally realistic concentrations of GLY (10, 100 and 1000 mg/L) to the mussel Mytilus galloprovincialis. Mussels were exposed for 7, 14 and 21 days and several biomarkers were measured in haemocytes/haemolymph (total haemocyte counts, haemocyte diameter and volume, haemolymph pH, haemolymph lactate dehydrogenase activity, haemocyte lysate lysozyme and acid phosphatase activities), as well as in gills and digestive gland (antioxidant enzyme and acetylcholinesterase activities). The concentrations of GLY and its main metabolite aminomethylphosphonic acid in the experimental tanks were also measured. The MANOVA analysis demonstrated that the experimental variables considered (exposure concentration, exposure duration, and their interaction) affected significantly biomarker responses. In addition, the two-way ANOVA analysis indicated that GLY was able to affect most of the cellular parameters measured, whereas antioxidant enzyme activities resulted to be influenced moderately. Interestingly, exposure to GLY reduced significantly acetylcholinesterase activity in gills. Although preliminary, the results of this study demonstrated that GLY can affect both cellular and biochemical parameters in mussels, highlighting a potential risk for aquatic invertebrates.

Néstor Merino-Díez, Aran Garcia-Lekue, Eduard Carbonell-Sanromà, Jingcheng Li, Martina Corso, Luciano Colazzo, Francesco Sedona, Daniel Sánchez-Portal, Jose Ignacio Pascual, and Dimas G. de Oteyza

ACS Nano (IF: 13.942)
DOI: 10.1021/acsnano.7b06765

We report on the energy level alignment evolution of valence and conduction bands of armchair-oriented graphene nanoribbons (aGNR) as their band gap shrinks with increasing width. We use 4,4’’-dibromo-para-terphenyl as molecular precursor on Au(111) to form extended poly-para-phenylene nanowires, which can be fused sideways to form atomically precise aGNRs of varying widths. We measure the frontier bands by means of scanning tunneling spectroscopy, corroborating that the nanoribbon’s band gap is inversely proportional to their width. Interestingly, valence bands are found to show Fermi level pinning as the band gap decreases below a threshold value around 1.7 eV. Such behavior is of critical importance to understand the properties of potential contacts in graphene nanoribbon-based devices. Our measurements further reveal a relatively unique system for studying Fermi level pinning by modifying an adsorbate´s band gap while maintaining an almost unchanged interface chemistry defined by substrate and adsorbate. 

Sven Urban, Igor Djerdj, Paolo Dolcet, Limei Chen, Maren Möller, Omeir Khalid, Hava Camuka, Rüdiger Ellinghaus, Chenwei Li, Silvia Gross, Peter J. Klar, Bernd Smarsly, Herbert Over

Chem. Mater., Just Accepted Manuscript
DOI: 10.1021/acs.chemmater.7b03091
I. F.: 9.466

The temporary storage of oxygen in a solid catalyst is imperative for many important industrial oxidation reactions in the gas phase, for instance the post-treatment of automotive exhaust gas. A peculiar mixed Ce-Zr (1:1) oxide, the ordered κ-Ce2Zr2O8 phase, is a promising catalytic material exhibiting an extraordinarily high oxygen storage capacity (OSC) and high thermal and chemical stability. In this paper, we elucidate the temperature-dependent transformation between the pyrochlore pyr-Ce2Zr2O7+x and κ-Ce2Zr2O8 phase upon oxygen uptake by in-situ X-ray diffraction, X-ray absorption and in-situ Raman spectroscopy, providing insights into the electronic and structural changes on the atomic level, which are at the heart of the extraordinarily high OSC. We demonstrate that the Ce3+ concentration can be followed in-situ by Raman spectroscopy of the electronic spin flip in the f-shell of trivalent cerium. The catalytic activity of the κ- e2Zr2O8 phase has been investigated without an additional active component such as Pt: While the high OSC of the kappa phase is beneficial for the oxidation of CO, the oxidation of HCl turns out to be not affected by the high OSC. 

Valentina Caputi, Ilaria Marsilio, Viviana Filpa, Silvia Cerantola, Genny Orso, Michela Bistoletti, Nicola Paccagnella, Sara De Martin, Monica Montopoli, Stefano Dall’Acqua, Francesca Crema, Iole-Maria Di Gangi, Francesca Galuppini, Isabella Lante, Sara Bogialli, Massimo Rugge, Patrizia Debetto, Cristina Giaroni and Maria Cecilia Giron

British Journal of Pharmacology

DOI: 10.1111/bph.13965

Impact factor: 5.773

First published: 30 August 2017

Background and Purpose. Gut microbiota is essential for the development of the gastrointestinal system, including the enteric nervous system (ENS). Perturbations of gut microbiota in early life have the potential to alter neurodevelopment leading to functional bowel disorders later in life. We examined the hypothesis that gut dysbiosis impairs the structural and functional integrity of the ENS, leading to gut dysmotility in juvenile mice.

Experimental Approach. To induce gut dysbiosis, broad-spectrum antibiotics were administered by gavage to juvenile (3weeks old) male C57Bl/6 mice for 14 days. Bile acid composition in the intestinal lumen was analysed by liquid chromatography-mass spectrometry. Changes in intestinal motility were evaluated by stool frequency, transit of a fluorescent-labelled marker and isometric muscle responses of ileal full-thickness preparations to receptor and non-receptor-mediated stimuli. Alterations in ENS integrity were assessed by immunohistochemistry and Western blot analysis.

Conclusions and Implications. Gut dysbiosis caused complex morpho-functional neuromuscular rearrangements, characterized by structural defects of the ENS and increased tachykininergic neurotransmission. Altogether, our findings support the beneficial role of enteric microbiota for ENS homeostasis instrumental in ensuring proper gut neuromuscular function during critical stages of development.

Paola Lanzafame, Siglinda Perathoner, Gabriele Centi*, Silvia Gross and Emiel J.M. Hensen

Journal: Catalysis Science & Technology

DOI: 10.1039/C7CY01067B

Impact factor: 5.773

Published on line 19.07.2017

This perspective discusses the general concepts that will guide future catalysis and related grand-challenges, based on "The European Roadmap on Science and Technology of Catalysis" prepared by the European Cluster on Catalysis. To adress the changing scenario in refinery and chemical production, and move to a low-carbon sustrainable future, the distinguishing elements of three grand-challenges for catalysis are discussed here: 1) catalysis to address the evolving energy and chemical scenario, 2) catalysis for a cleaner and sustainable future, and 3) addressing catalysis complexity, the latter being organized in three sub-topics: advanced design of novel catalysts, understanding catalysts from molecular to material scale, and expanding catalysis concepts

 

A. Politano, D. Campi, M. Cattelan, I. Ben Amara, S. Jaziri, A. Mazzotti, A. Barinov, B. Gürbulak, S. Duman, S. Agnoli, L. S. Caputi, G. Granozzi, and A. Cupolillo

Scientific Reports (IF= 5.228)

DOI : 10.1038/s41598-017-03186-x

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.

Vassalini, I., Borgese, L., Mariz, M., Polizzi, S., Aquilanti, G., Ghigna, P., Sartorel, A., Amendola, V. and Alessandri, I.

Chem. Int. Ed., 2017
doi: 10.1002/anie.201703387

Au–Fe nanoparticles synthesized by laser ablation in solution exhibit enhanced activity in the oxygen evolution reaction (see diagram). The results open exciting perspectives for using nanoalloys in catalysis and energy conversion.

C. Suchomski, D. J. Weber, P. Dolcet, A. Hofmann, P. Vöpel, J. Yue, M. Einert, M. Möller, S. Werner, S. Gross, I. Djerdj, T. Brezesinski and B. M. Smarsly

Journal of Material Chemistry A
DOI: 10.1039/c7ta02316b
I. F.: 8.262
First published online 24 April 2017

A cost-effective and tailored synthesis route for the preparation of cubic ZrO2 nanocrystals with high dispersibility was developed. The procedure is straightforward and produces uniform 2–3 nm particles of excellent yield when applying microwave dielectric heating as a “green” method. Furthermore, it can be applied to a wide range of batch sizes (from 0.5 to 20 g ZrO2), which makes it interesting for industrial applications, and also lends itself to the preparation of yttria-stabilized ZrO2 nanocrystals with varying doping levels. The work provides a blueprint for the fabrication of high-quality nanoparticles and structured materials thereof and is likely to trigger further research in the field of solution-processed metal oxides.

 

Sabrina Antonello, Tiziano Dainese, Fangfang Pan, Kari Rissanen, and Flavio Maran

Thiolate-protected metal clusters are materials of ever-growing importance in fundamental and applied research. Knowledge of their single-crystal X-ray structures has been instrumental to enable advanced molecular understanding of their intriguing properties. So far, however, a general, reliable, chemically clean approach to prepare single crystals suitable for accurate crystallographic analysis was missing. Here we show that single crystals of thiolate-protected clusters can be grown in large quantity and very high quality by electrocrystallization.

J. Am. Chem. Soc., Article ASAP 

Open Access

DOI: 10.1021/jacs.7b00568

Publication Date (Web): March 10, 2017

AlphaGalileo University of Jyväskylä (Finland)

 

Arianna Minelli, Paolo Dolcet, Stefano Diodati, Sandra Gardonio, Claudia Innocenti, Denis Badocco, Stefano Gialanella, Paolo Pastore, Luciano Pandolfo, Andrea Caneschi, Angela Trapananti Silvia Gross

Journal of Material Chemistry C

DOI: 10.1039/c6tc05636a

I. F.: 5.066

First published online 23 Feb 2017

A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment was demonstrated to be very effective in yielding and stabilising, at relatively low temperature (180°C) and in water, the crystallisation of nanostructured manganites. The subcritical hydrothermal approach was in fact shown to play a key role in stabilising phases which are generally achieved at much higher temperatures, and in harsher conditions, thus disclosing an exciting alternative for their synthesis. As a result of this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 as a pure compound. This is particularly notable, as very few records concerning this compound are available in literature. The manganites were characterised from a structural (XRPD and SAED, morphological (TEM and SEM) and compositional (XPS, ICP-MS, XAS and CHN analysis) point of view. Since these materials are particularly interesting for functional properties ascribed to their magnetic behaviour, SQUID was employed to study their magnetic properties, yielding a response that could indicate either ferrimagnetic or antiferromagnetic behaviour in CuMnO2 and ZnMnO3.

Ivan Guryanov,    Federico Polo,    Evgeniy Ubyvovk,    Evgenia Vlakh, Tatiana Tennikova,  Armin Tahmasbi Rad, Mu-Ping Nieh and FLAVIO MARAN

Chem. Sci., 2017, Accepted Manuscript

DOI: 10.1039/C6SC05187A  

First published online 02 Feb 2017

Poly(amino acid)-coated gold nanoparticles hold promises in biomedical applications, particularly because they combine unique physicochemical properties of the gold core, excellent biocompatibility, and easy functionalization of the poly(amino acid)-capping shell. Here we report a novel method of the preparation of robust hybrid core-shell nanosystems consisting of a Au144 cluster and a densely grafted polylysine layer. Linear polylysine chains were grown by direct N-carboxyanhydride (NCA) polymerization onto ligands capping the gold nanocluster. The density of the polylysine chains and the thickness of the polymer layer strongly depend on the amount and concentration of the NCA monomer and the initiator. The optical spectra of the so-obtained core-shell nanosystems show a strong surface plasmon resonance (SPR) like band at 531 nm. In fact, despite the gold-cluster size is maintained and the absence of interparticle aggregation, the polylysine-capped clusters behave as if they had a diameter nearly 4 times larger. To the best of our knowledge, this is the first observation of the growth of a fully developed, very stable SPR-like band for a gold nanocluster of such dimension. The robust polylysine protective shell makes the nanoparticles very stable under conditions of chemical etching, in the presence of glutathione, and at different pH values, without gold core deshielding or alteration of the SPR-like band. This polymerization method can be conceivably extended to prepare core-shell nanosystems based on other mono- or co-poly(amino acids). 

Simona Neri, Sergio Garcia Martin, Cristian Pezzato and Leonard J. Prins

DOI: 10.1021/jacs.6b12932

Published: January 2017

The activity of a gold nanoparticle-based catalyst can be reversibly up- and down-regulated by light. Light is used to switch a small molecule between cis- and trans-isomers, which inhibits the catalytic activity of the nanoparticles to different extent. The system is functional in aqueous buffer, which paves the way for integrating the system in biological networks.


Fabio Rizzo, Federico Polo, Gregorio Bottaro, Simona Fantacci, Sabrina Antonello, Lidia Armelao, Silvio Quici, and Flavio Maran

DOI: 10.1021/jacs.6b12247

Published: January 15, 2017

We describe the synthesis, computational analysis, photophysics, electrochemistry and electrochemiluminescence (ECL) of a series of compounds formed of two triphenylamines linked by a fluorene or spirobifluorene bridge. The
phenylamine moieties were modified at the para-position of the two external rings by electron-withdrawing or electron-donating substituents. These modifications allowed for fine-tuning of the photoluminescence (PL) and ECL emission from blue to green,
with an overall wavelength span of 73 (PL) and 67 (ECL) nm, respectively. For all compounds, we observed a very high PL quantum yield (79−89%) and formation of stable radical ions. The ECL properties were investigated by direct annihilation of the
electrogenerated radical anion and radical cation. The radical-ion annihilation process is very efficient and causes an intense greenish-blue ECL emission, easily observable even by naked eye, with quantum yield higher than the standard 9,10-
diphenylanthracene. The ECL spectra show one single band that almost matches the PL band. Because the energy of the annihilation reaction is higher than that required to form the singlet excited state, the S-route is considered the favored pathway followed by the ECL process in these
molecules. All these features point to this type of molecular system as promising for ECL applications. 

 Alice Antonello, Gerhard Jakob, Paolo Dolcet, Rebecca Momper, Maria Kokkinopoulou, Katharina Landfester, Rafael Muñoz-Espí, Silvia Gross*

Journal: Chemistry of Materials

IF: 9.407

DOI: 10.1021/acs.chemmater.6b03467

Accepted December 30 2016

Crystalline first row transition metal (Mn, Fe, Co, Ni, Cu and Zn) ferrites were prepared by an unprecedented synergetic combination of miniemulsion synthesis and solvothermal route, pursuing unconventional conditions in terms of space confinement, temperature and pressure. This synergy allowed for obtaining different crystalline ferrites at much lower temperature (i.e., 80 °C) than usually required and without any post-synthesis thermal treatment. X-ray diffraction (XRD) revealed that analogous ferrites synthesized by miniemulsion at ambient pressure or in bulk either at ambient pressure or under solvothermal conditions did not result in comparatively highly crystalline products. To follow the structural evolution at local level as a function of reaction time and depending on the synthesis conditions, X-ray absorption spectroscopy (XAS) was used to determine the cation distribution in these structures. Well-defined nanostructures were observed by transmission electron microscopy (TEM). Concerning their functional behavior, the synthesized ferrites presented superparamagnetism and were found to be active oxidation catalysts, as demonstrated for the oxidation of styrene, taken as a model reaction. Thanks to the magnetic properties, the ferrites can be easily recovered from the reaction medium, after the catalysis, by magnetic separation and reused for several cycles without losing activity.

 Marilena Di Valentin*, Marco Albertini, Maria Giulia Dal Farra, Enrico Zurlo, Laura Orian, Antonino Polimeno, Marina Gobbo and Donatella Carbonera

Journal: Chemistry-A European Journal IF: 5.771

DOI: 10.1002/chem.201603666

First published:9 November 2016

We report a pulsed electron paramagnetic resonance spectroscopic ruler for high-sensitive and accurate measurement of distances and distance distributions based on a novel spin labelling strategy. The ruler consists of a series of α-helical peptides, labeled at the N-terminal end with a porphyrin moiety, which can be excited to the triplet state, and with a nitroxide at various sequence positions, spanning distances in the range 1.8-8 nm. The new methodology has a high potential for measuring nanometer distances in proteins due to the distinctive properties of the porphyrin triplet state. Appropriate spin-labeling protocols can finally extend this novel strategy to any macromolecular system with a general impact in structural (bio)chemistry.

Cesare Benedetti, Alessandro Cazzolaro, Mauro Carraro, Robert Graf, Katharina Landfester, Silvia Gross*, and Rafael Muñoz-Espí*

Journal: ACS Applied Materials & Interfaces IF: 7.145

DOI: 10.1021/acsami.6b07023

Accepted 9 September 2016

Organic–inorganic hybrid nanoparticles are prepared by free-radical copolymerization of methyl methacrylate (MMA) with the structurally well-defined methacrylate-functionalized zirconium oxocluster Zr4O2(methacrylate)12. The polymerization process occurs in the confined space of miniemulsion droplets. The formation of covalent chemical bonds between the organic and the inorganic counterparts improves the distribution of the guest species (oxoclusters) in the polymer particles, overcoming problems related to migration, leaching and stability. Because of the presence of a high number of double bonds (12 per oxocluster), the oxoclusters act as efficient cross-linking units for the resulting polymer matrix, thus ruling its swelling behavior in organic solvents. The synthesized hybrid nanostructures are applied as heterogeneous systems in the catalytic oxidation of an organic sulfide to the corresponding sulfoxide and sulfone by hydrogen peroxide, displaying quantitative sulfide conversion in 4-24 h with more than 2000 catalytic cycles.

A. Politano, M. Cattelan, D.W. Boukhvalov, D. Campi, A. Cupolillo, S. Agnoli, N.G. Apostol, P. Lacovig, S. Lizzit, D. Farías, G. Chiarello, G. Granozzi, and R. Larciprete 

ACS Nano (IF: 12.881)

DOI: 10.1021/acsnano.6b00554

By means of a combination of surface-science spectroscopies and theory, we have investigated the mechanisms ruling the catalytic role of epitaxial graphene (Gr) grown on transition-metal substrates for the production of hydrogen from water. Water decomposition at the Gr/metal interface at room temperature provides a hydrogenated Gr sheet, which is buckled and decoupled from the metal substrate. We evaluated the performance of Gr/metal interface as a hydrogen storage medium, with a storage density in the Gr sheet comparable with state-of-the-art materials (1.42 wt.%). Moreover, thermal programmed reaction experiments showed that molecular hydrogen can be released upon heating the water-exposed Gr/metal interface above 400 K. The Gr hydro/dehydrogenation process might be exploited for an effective and eco-friendly device to produce (and store) hydrogen from water, i.e. starting from an almost unlimited source.

Sven Urban, Paolo Dolcet, Maren Möller, Limei Chen, Peter J. Klar, Igor Djerdj, Silvia Gross, Bernd Smarsly, Herbert Over

Applied Catalysis B: Environmental

I. F.: 7.435

It is known that the k-Ce2Zr2O8 phase is an active oxidation catalyst with an extraordinarily high oxygen storage capacity. The k-Ce2Zr2O8 phase is synthesized starting from t-Ce0.5Zr0.5O2 solid solution which is reduced by hydrogen at high temperatures to form the pyrochlore Ce2Zr2O7 phase (pyr-Ce2Zr2O7) with high degree of ordering of the cationic sublattice. The final step in the synthesis of the k-Ce2Zr2O8 phase includes a mild re-oxidation of pyr-Ce2Zr2O7 at around 600 °C under atmospheric conditions. Yet, the optimum synthesis of the k-Ce2Zr2O8 phase is still not settled since most of the previous studies used reduction temperatures of 1300 °C and below. We show in contribution that 1300 °C is not sufficient to warrant the preparation of phase-pure pyr-Ce2Zr2O7 and k-Ce2Zr2O8, but rather that temperatures as high as 1500 °C are required to assure phase purity. This conclusion is drawn from extended X-ray diffraction and X-ray absorption spectroscopy analysis together with Raman spectroscopy, providing in-depth details of the structure on the level of both, the evolution of the special periodic structure and the coordination of the metal atoms. 

 

Annalisa Dalzini, Christian Bergamini, Barbara BiondiMarta De ZottiGiacomo Panighel, Romana Fato, Cristina PeggionMarco Bortolus & Anna Lisa Maniero

Scintific Reports

doi:10.1038/srep24000

IF: 5.578

Peptaibols are peculiar peptides produced by fungi as weapons against other microorganisms. Previous studies showed that peptaibols are promising peptide-based drugs because they act against cell membranes rather than a specific target, thus lowering the possibility of the onset of multi-drug resistance, and they possess non-coded α-amino acid residues that confer proteolytic resistance. Trichogin GA IV (TG) is a short peptaibol displaying antimicrobial and cytotoxic activity. In the present work, we studied thirteen TG analogues, adopting a multidisciplinary approach. We showed that the cytotoxicity is tuneable by single amino-acids substitutions. Many analogues maintain the same level of non-selective cytotoxicity of TG and three analogues are completely non-toxic. Two promising lead compounds, characterized by the introduction of a positively charged unnatural amino-acid in the hydrophobic face of the helix, selectively kill T67 cancer cells without affecting healthy cells. To explain the determinants of the cytotoxicity, we investigated the structural parameters of the peptides, their cell-binding properties, cell localization, and dynamics in the membrane, as well as the cell membrane composition. We show that, while cytotoxicity is governed by the fine balance between the amphipathicity and hydrophobicity, the selectivity depends also on the expression of negatively charged phospholipids on the cell surface.

Yun Luo, Luis Alberto Estudillo-Wong, Laura Calvillo, Gaetano Granozzi, Nicolas Alonso-Vante 

Journal of Catalysis 2016

DOI:10.1016/j.jcat.2016.03.001

IF: 6.921

Carbon supported PdCu alloy (PdCu/C-1) with surface atomic Pd/Cu ratio of 0.8/1 was successfully synthesized via an easy and cheap chemical route, using a Cu-MOF precursor (HKUST-1). This material shows nanorod-like morphology. The addition of Cu results in a lattice contraction (afcc = 0.3869 nm), and an increase of micro-strain (ε = 0.71 %) and stacking fault (α = 5.20 %) with respect to Pd/C NPs (afcc = 0.3889 nm, ε = 0.37 %, α = 1.98 %) prepared via the same chemical route. When using the CuCl2 precursor (PdCu/C-2), the micro-strain (ε = 0.47 %) and stacking-fault (α = 4.10 %) values also increases with respect to Pd/C NPs. The XPS characterization demonstrates the predominant metallic character of Cu and the formation of a PdCu alloy with a stoichiometry close to 1:1 in the near surface region. The use of a sacrificial HKUST-1 precursor is crucial for the formation of PdCu alloy. The electrochemical behavior of the MOF-derived PdCu/C sample is rather different from the other reference catalysts. Based on the results of CO-stripping, the CO-oxidation potential could be related to both micro-strain and stacking-fault. This fact reveals that the electrochemistry of this sample is associated with surface defects induced by Cu atoms in the PdCu alloy. Moreover, the ORR activity is improved on the MOF-derived PdCu/C sample with respect to other Pd-based catalysts, demonstrating a positive effect of the surface defects induced by alloyed PdCu NPs prepared from HKUST-1. Compared with commercial Pt/C (JM) catalyst, the ORR mass activity of PdCu/C-1 was lower in acid medium, whereas it was around 3-fold higher in alkaline solution. Therefore, the synthesis of PdCu nanoalloyed NPs, using HKUST-1 precursors, not only extends the application of MOF in the field of electrocatalysis, but also brings a new methodology in advanced non-Pt active centers for the ORR.

Yun Luo, Laura Calvillo, Carole Daiguebonne, Maria K. Daletou, Gaetano Granozzi, Nicolas Alonso-Vante

Applied Catalysis B: Environmental 2016 (IF=7.435)

DOI: 10.1016/j.apcatb.2016.02.028

Advanced Pt/CeOx/C nanocomposite, where C = porous carbon and multi-walled carbon nanotube (MWCNT), was synthesized using a precursor based on Ce-containing metal organic framework (MOF), via carbonyl chemical route, followed by heat-treatment at 900 °C under argon atmosphere. The use of MOF lead to the formation of CeOx intimately contacted to Pt surface that protects Pt NPs against agglomeration. CeOx, derived from MOF(Ce), interacts with Pt NPs, stabilizing Pt0 and Ce3+ state in the nanocomposite. The surface electrochemistry of Pt/CeOx/C nanocomposite showed the promotion of H and CO adsorption, thus higher Pt active surface area with respect to the samples prepared at lower temperatures and commercial Pt/C (JM) catalyst. The ORR activity and stability was highly enhanced, outperforming DOE 2015/2017 target in half-cell. Finally, such an innovative composite was validated as cathode catalyst in a H2/O2 μLFFC system. Compared with other homemade and Pt/C (JM) cathodic catalysts, the cell power density was enhanced by a factor of ca. 1.2 – 1.7. All these facts assess the significant role of CeOx, based on MOF(Ce) precursor, in the formation of Pt/CeOx/C nanocomposite, leading to a modified Pt surface and resulting enhanced ORR kinetic and stability. This work has also demonstrated that the novel Pt/CeOx/C nanocomposite can be in-situ prepared at high temperature (900 °C under inert gas) where both MWCNTs and porous carbon are key ingredients. Our study, indeed, extends the application of MOF materials in preparation of Pt-based nanomaterials for energy conversion.