PUBLICATIONS
2020|Action number: CA15107
The Nanonauts Comic Book
Author(s): Lottie Keene and Tony Keene
Publisher(s): MultiComp
Full PDF DownloadThe Nanonauts is a comic book aimed at 10-year olds that explores the world of nanomaterials and how they find applications in real life. The Nanonauts are two intrepid scientists, Silvia and Jan, that can shrink down to the nanoscale and investigate how carbon nanomaterials work to help with making self-healing gels and mopping up oil spills. The booklet gives an overview of the COST Action for teachers with links to MultiComp website. Individual researcher outputs are represented as one-page cartoons that can be printed at poster size. At the back of the booklet, there is a cut-out sheet that expands out to give a graphene model.The characters and artwork are the work of the school-age daughter of one of the MultiComp members, helping to create a genuine connection between children and research outputs.
2018|Action number: CA15107
EDITORIAL: Advances in nanocarbon composite materials
Author(s): Sharali Malik, Arkady V. Krasheninnikov, and Silvia Marchesan
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.9.3
Beilstein-JournalsMaterials have always been crucial to human development, to the point of being used as a reference to name specific stages of development. The first was the Stone Age, then the Bronze Age and then the Iron Age and on to their equivalents in modern times viz. the Plastic Age, the Silicon Age and the Nanomaterials Age. About 70% of all technical innovations (as estimated by the German federal government) can be attributed either directly or indirectly to the properties of the materials used – solutions are being explored on how to interface nanomaterials with other components in the macroscopic world. Therefore, we could reasonably state that we are entering the Composite Age. In particular, nanocarbons display unique properties to innovate in practically all technological sectors and branches of industry. This cutting-edge use of nano-augmented composite materials has the potential to reduce environmental pollution, to conserve resources, to save energy, and generally, to improve the quality of our lives.
2020|Action number: CA15107
Surface-Controlled Crystal Alignment of Naphthyl End-Capped Oligothiophene on Graphene: Thin-Film Growth Studied by in Situ X-ray Diffraction
Author(s): Mathias K. Huss-Hansen, Martin Hodas, Nada Mrkyvkova, Jakub Hagara, Bjarke B. E. Jensen, Andreas Osadnik, Arne Lützen, Eva Majková, Peter Siffalovic, Frank Schreiber, Luciana Tavares, Jakob Kjelstrup-Hansen, and Matti Knaapila
Publisher(s): Langmuir
ISBN/ISSN/DOI: doi.org/10.1021/acs.langmuir.9b03467
ACSWe report on the microstructure, morphology, and growth of 5,5′-bis(naphth-2-yl)-2,2′-bithiophene (NaT2) thin films deposited on graphene, characterized by grazing incidence X-ray diffraction (GIXRD) and complemented by atomic force microscopy (AFM) measurements. NaT2 is deposited on two types of graphene surfaces: custom-made samples where chemical vapor deposition (CVD)-grown graphene layers are transferred onto a Si/SiO2 substrate by us and common commercially transferred CVD graphene on Si/SiO2. Pristine Si/SiO2 substrates are used as a reference. The NaT2 crystal structure and orientation depend strongly on the underlying surface, with the molecules predominantly lying down on the graphene surface (face-on orientation) and standing nearly out-of-plane (edge-on orientation) on the Si/SiO2 reference surface. Post growth GIXRD and AFM measurements reveal that the crystalline structure and grain morphology differ depending on whether there is polymer residue left on the graphene surface. In situ GIXRD measurements show that the thickness dependence of the intensity of the (111) reflection from the crystalline edge-on phase does not intersect zero at the beginning of the deposition process, suggesting that an initial wetting layer, corresponding to 1-2 molecular layers, is formed at the surface-film interface. By contrast, the (111) reflection intensity from the crystalline face-on phase grows at a constant rate as a function of film thickness during the entire deposition.
2020|Action number: CA15107
A New FeIII Substituted Arsenotungstate [FeIII2(AsIIIW6O23)2(AsIIIO3H)2]12−: Synthesis, Structure, Characterization and Magnetic Properties
Author(s): Masooma Ibrahim, Yan Peng, and Christopher E. Anson
Publisher(s): Magnetochemistry
ISBN/ISSN/DOI: doi.org/10.3390/magnetochemistry6040054
MPDIThe iron(III)-containing arsenotungstate [FeIII2(AsIIIW6O23)2(AsIIIO3H)2]12− (1) was prepared via a simple, one-pot reaction in aqueous basic medium. The compound was isolated as its sodium salt, and structurally-characterized by Single Crystal X-ray Diffraction (SCXRD), Powder X-ray Diffraction (PXRD), Fourier-Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA) and elemental analysis. Its magnetic properties are reported; the antiferromagnetic coupling between the two FeIII centers is unusually weak as a result of the bridging geometry imposed by the rigid arsenotungstate metalloligands.
2020|Action number: CA15107
Thermal stabilization of poly(acrylonitrile-co-itaconic acid) nanofibers as carbon nanofiber precursor
Author(s): Ezgi Ismar, Matej Micusik, Ilknur Gergin, Maria Omastova, and A. Sezai Sarac
Publisher(s): Polymer Degradation and Stability
ISBN/ISSN/DOI: doi.org/10.1016/j.polymdegradstab.2020.109142
ScienceDirectThe thermal treatment of poly (acrylonitrile-co-itaconic acid), (P (AN-co-IA)) and polyacrylonitrile (PAN) under the oxygen atmosphere has a complex mechanism which strongly affects the properties of final product carbon nanofiber. Not only precursor composition but also oxidation treatment parameters play a key role in the achievement of the desired properties of the end product; carbon nanofiber. PAN and P (AN-co-IA) based nanofibers were fabricated via electrospinning technique and later treated at different temperatures to investigate the oxidation procedure in the presence of itaconic acid as a copolymer form. Description of the oxidation (thermal stabilization) route of nanofibers is challenging thus powerful characterization tools such as electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and FTIR-ATR are used for characterization and evaluated dependently. All obtained results are pointed out that; IA addition has a positive effect on the oxidation process in nanoscale in terms of reduction of applied temperature and time compared to homopolymer PAN. Spectroscopic results were also correlated with the equivalent Circuit Parameters of Electrochemical Impedance Spectroscopic Measurements, where oxidation and carbonization stages can be followed easily due to the formation of heterocyclic and conjugated structures by thermal treatments.
2020|Action number: CA15107
Comparative NMR Relaxivity Study of Polyoxometalate-Based Clusters [Mn4(H2O)2(P2W1SO56)2]16− and [{Dy(H2O)6}2Mn4(H2O)2(P2W15O56)2]10− from 20 MHz to 1.2 GHz
Author(s): Masooma Ibrahim, Thomas Rudszuck, Banan Kerdi, Steffen Krämer, Gisela Guthausen, and Annie K. Powell
Publisher(s): Applied Magnetic Resonance
ISBN/ISSN/DOI: doi.org/10.1007/s00723-020-01267-1
SpringerNuclear Magnetic Resonance relaxivities are a measure for the sensitivity of a contrast agent (CA), i.e. the potential of a paramagnetic moiety to enhance longitudinal and transverse relaxation of molecules in its near neighbourhood. The underlying mechanism is called Paramagnetic Relaxation Enhancement (PRE). The relaxivity, characterizing PRE, depends not only on the external applied magnetic field but also depends on numerous factors, such as number of coordinated water molecules, water exchange rate, rotational diffusion, first and second coordination hydration sphere, electronic and magnetic properties of paramagnetic centers and the molecular shape/size of the CA. Relaxation rates are usually normalized to the concentration of the contrast agent to provide the relaxivities. To investigate the influence of these factors on PRE of newly synthesized potential CA, two paramagnetic metals containing polyoxometalates (POMs) [Mn4(H2O)2(P2W15O56)2]16− (Mn4-P2W15) and [{Dy(H2O)6}2Mn4(H2O)2(P2W15O56)2]10− (Dy2Mn4-P2W15) were selected as models to be studied at 1H Larmor frequencies from 20 MHz to 1.2 GHz. Structurally, the POM Dy2Mn4-P2W15 is similar to the tetra-nuclear manganese(II)-substituted sandwich-type POM Mn4-P2W15, with the two coordinated DyIII cations acting as linkers connecting Mn4-P2W15 units, thus forming a 1D ladder-like chain structure based on sandwich-type rungs strung together by the dysprosium cations. This study shows that POM (Dy2Mn4-P2W15) is a promising CA at high magnetic fields and proves that the use of heterometallic clusters is an effective strategy to increase PRE due to the synergistic effects from different metal ions.
2020|Action number: CA15107
Reversible changes in the electronic structure of carbon nanotube-hybrids upon NO2 exposure under ambient conditions
Author(s): Filippo Fedi, Oleg Domanov, Hidetsugu Shiozawa, Kazuhiro Yanagi, Paolo Lacovig, Silvano Lizzit, Andrea Goldoni, Thomas Pichlera, and Paola Ayala
Publisher(s): Journal of Materials Chemistry A
ISBN/ISSN/DOI: doi.org/10.1039/D0TA02749A
RSCThe properties of single-walled carbon nanotubes provide them with enormous potential as gas sensors but true effectiveness can really be expected if their interaction with sensing targets can be controlled and their recovery is granted. It is shown here how metallicity-sorted tubes filled with nickel(II) acetylacetonate in the molecular form, and also subsequently transformed into metal clusters encapsulated in the hollow core, are able to unfold two major challenges: tuning the gas-tube interaction and achieving the desorption of NO2 at ambient temperature. Aiming at the control of the sensitivity of the nanotubes to NO2 at room temperature, by making use of time resolved photoemission we observed that in semiconducting nanotubes the chemical potential is pinned inside their energy gap shifted to the onset of the conduction band when filled with nanoclusters. This shows that cluster filling is a key to high sensitivity, opening the possibility for a very high desorption at ambient temperature.
2020|Action number: CA15107
Unique cellular network formation guided by heterostructures based on reduced graphene oxide - Ti3C2Tx MXene hydrogels
Author(s): Jacek K. Wychowaniec, Jagoda Litowczenko, Krzysztof Tadyszak, Varun Natu, Claudia Aparicio, Barbara Peplińska, Michel W. Barsoum, Michal Otyepka, and Błażej Scheibe
Publisher(s): Acta Biomaterialia
ISBN/ISSN/DOI: doi.org/10.1016/j.actbio.2020.08.010
ElsevierTwo-dimensional (2D) materials remain highly interesting for assembling three-dimensional (3D) structures, among others, in the form of macroscopic hydrogels. Herein, we present a novel approach for inducing chemical inter-sheet crosslinks via an ethylenediamine mediated reaction between Ti3C2Tx and graphene oxide in order to obtain a reduced graphene oxide-MXene (rGO-MXene) hydrogel. The composite hydrogels are hydrophilic with a stiffness of ∼20 kPa. They also possess a unique inter-connected porous architecture, which led to a hitherto unprecedented ability of human cells across three different types, epithelial adenocarcinoma, neuroblastoma and fibroblasts, to form inter-connected three-dimensional networks. The attachments of the cells to the rGO-MXene hydrogels were superior to those of the sole rGO-control gels. This phenomenon stems from the strong affinity of cellular protrusions (neurites, lamellipodia and filopodia) to grow and connect along architectural network paths within the rGO-MXene hydrogel, which could lead to advanced control over macroscopic formations of cellular networks for technologically relevant bioengineering applications, including tissue engineering and personalized diagnostic networks-on-chip.
2020|Action number: CA15107
Carbon nanostructure morphology templates nanocomposites for phosphoproteomics
Author(s): Susy Piovesana, Daniel Iglesias, Manuel Melle-Franco, Slavo Kralj, Chiara Cavaliere, Michele Melchionna, Aldo Laganà, Anna L. Capriotti & Silvia Marchesan
Publisher(s): Nano Research
ISBN/ISSN/DOI: doi.org/10.1007/s12274-020-2643-x.
SpringerProtein and peptide phosphorylation regulate numerous pathological processes, however, their characterization is challenging due to their low abundance and transient nature. Therefore, nanomaterials are being developed to address this demanding task. In particular, carbon nanostructures are attracting interest as scaffolds for functional nanocomposites, yet only isolated studies exist on the topic, and little is known on the effect of nanocarbon morphology on templating nanocomposites. In this work, we compared oxidized carbon nanotubes, graphene oxide, oxidized carbon nanohorns and oxidized graphitized carbon black, as scaffolds for magnetized nanocomposites. The nanomaterials were extensively characterized with experimental and <i>in silico</i> techniques. Next, they were applied to phosphopeptide enrichment from cancer cell lysates for NanoHPLC-MS/MS, with selectivity as high as nearly 90% and several-thousand identification hits. Overall, new insights emerged for the understanding and the design of nanocomposites for phosphoproteomics.
2020|Action number: CA15107
Synthesis, Characterization, Electrochemistry, Photoluminescence and Magnetic Properties of a Dinuclear Erbium(III)-Containing Monolacunary Dawson-Type Tungstophosphate: [{Er(H2O)(CH3COO)(P2W17O61)}2]16−
Author(s): Masooma Ibrahim, Ananya Baksi, Yan Peng, Firas Khalil Al-Zeidaneen, Israël M. Mbomekallé, Pedro de Oliveira, and Christopher E. Anson
Publisher(s): Applied Magnetic Resonance
ISBN/ISSN/DOI: doi.org/10.3390/molecules25184229
MPDIReaction of the trilacunary Wells−Dawson anion {α-P2W15O56}12− with ErIII ion in a 1 M LiOAc/HOAc buffer (pH 4.8) solution produces a dinuclear erbium(III) substituted sandwich-type structure [{Er(H2O)(CH3COO)(P2W17O61)}2]16− (1). The isolated compound was structurally characterized using single crystal and powder X-ray diffraction, FTIR spectroscopy, mass spectrometry and thermogravimetric analysis. The electrochemical, electrocatalytic, photoluminescence and magnetic properties of 1 were investigated.
2020|Action number: CA15107
Tuning Properties of Partially Reduced Graphene Oxide Fibers upon Calcium Doping
Author(s): Krzysztof Tadyszak, Jacek K. Wychowaniec, Karol Załęski, Emerson Coy, Łukasz Majchrzycki, and Raanan Carmieli
Publisher(s): Nanomaterials
ISBN/ISSN/DOI: doi.org/10.3390/nano10050957
MPDIThe arrangement of two-dimensional graphene oxide sheets has been shown to influence physico-chemical properties of the final bulk structures. In particular, various graphene oxide microfibers remain of high interest in electronic applications due to their wire-like thin shapes and the ease of hydrothermal fabrication. In this research, we induced the internal ordering of graphene oxide flakes during typical hydrothermal fabrication via doping with Calcium ions (~6 wt.%) from the capillaries. The Ca2+ ions allowed for better graphene oxide flake connections formation during the hydrogelation and further modified the magnetic and electric properties of structures compared to previously studied aerogels. Moreover, we observed the unique pseudo-porous fiber structure and flakes connections perpendicular to the long fiber axis. Pulsed electron paramagnetic resonance (EPR) and conductivity measurements confirmed the denser flake ordering compared to previously studied aerogels. These studies ultimately suggest that doping graphene oxide with Ca2+ (or other) ions during hydrothermal methods could be used to better control the internal architecture and thus tune the properties of the formed structures.
2020|Action number: CA15107
Oligoether Ester-Functionalized ProDOT Copolymers on Si/Monolayer Graphene as Capacitive Thin Film Electrodes
Author(s): Tolga Karazehir, Baran Sarac, Hans-Detlev Gilsing, Jürgen Eckert, and A. Sezai Sarac
Publisher(s): Journal of The Electrochemical Society
ISBN/ISSN/DOI: doi.org/10.1149/1945-7111/ab7f85
IOPIn this study, electrochemical polymerization of 3,4-propylenedioxythiophene (ProDOT 1), ProDOT bearing oligoether ester (ProDOT-EO-ester 2) and their copolymerization onto homogeneously CVD coated nano-graphene/Si support is realized to attain graphene/ProDOT based copolymer hybrid nanostructures. By introducing oligoether side chain to ProDOT backbone and using different [ProDOT]/[ProDOT-EO-ester] molar ratios ensures a considerable decrease in oxidation potential of polymer allowing tunable properties to copolymers revealing improvement electrochemical capacitance and electrochemical activity which are clearly reflected by the experimental results. Capacitive behavior of copolymers is determined by electrochemical impedance spectroscopy, cyclic voltammetry. Moreover, The structural, morphological and spectroscopic characterization of the copolymers is investigated by XRD, AFM, SEM, EDX, FTIR, and Raman, respectively. By the increase of ProDOT in the copolymer composition, the higher dopant concentration is attained suggesting an enhanced conductivity agree well with the impedance and CV results, where the copolymerization of ProDOT 1 and ProDOT-EO-ester 2 in equal molarity results in the highest specific capacitance and redox activity. The adopted equivalent circuit model for polymers is in good agreement with the experimental data of impedance. Due to the difference in conjugated structure between ProDOT and ProDOT-EO-ester by the presence of the EO-ester group leads to a decrease in charge transfer resistance with increasing mole fraction of ProDOT-EO-ester. The charge transfer resistance of [ProDOT]0/[ProDOT-EO-ester]0 = 1:1 coated Si/graphene is nearly 51 and 24 times lower value compared to those of PProDOT and P(ProDOT-EO-ester) homopolymers coated Si/graphene, respectively, confirming that the copolymerization improves the electron conduction. By Mott-Schottky measurements, increasing mole fraction of ProDOT-EO-ester 2 in copolymer composition results in the alteration of semiconducting behavior. The developed graphene-polymer hybrid electrodes can be a potential candidate for energy storage devices.
2020|Action number: CA15107
Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots
Author(s): Krzysztof Tadyszak, Andrzej Musiał, Adam Ostrowski, and Jacek K. Wychowaniec
Publisher(s): Nanomaterials
ISBN/ISSN/DOI: doi.org/10.3390/nano10040798
MPDICarbon nanostructures are utilized in a plethora of applications ranging from biomedicine to electronics. Particularly interesting are carbon nanostructured quantum dots that can be simultaneously used for bimodal therapies with both targeting and imaging capabilities. Here, magnetic and optical properties of graphene oxide quantum dots (GOQDs) prepared by the top-down technique from graphene oxide and obtained using the Hummers' method were studied. Graphene oxide was ultra-sonicated, boiled in HNO3, ultra-centrifuged, and finally filtrated, reaching a mean flake size of ~30 nm with quantum dot properties. Flake size distributions were obtained from scanning electron microscopy (SEM) images after consecutive preparation steps. Energy-dispersive X-ray (EDX) confirmed that GOQDs were still oxidized after the fabrication procedure. Magnetic and photoluminescence measurements performed on the obtained GOQDs revealed their paramagnetic behavior and broad range optical photoluminescence around 500 nm, with magnetic moments of 2.41 µB. Finally, electron paramagnetic resonance (EPR) was used to separate the unforeseen contributions and typically not taken into account metal contaminations, and radicals from carbon defects. This study contributes to a better understanding of magnetic properties of carbon nanostructures, which could in the future be used for the design of multimodal imaging agents.
2019|Action number: CA15107
Syntheses, Crystal Structure, Electrocatalytic, and Magnetic Properties of the Monolanthanide-Containing Germanotungstates [Ln(H2O)nGeW11O39]5– (Ln = Dy, Er, n = 4,3)
Author(s): Masooma Ibrahim, Israël M. Mbomekallé, Pedro de Oliveira, Ananya Baksi, Anthony B. Carter, Yan Peng, Thomas Bergfeldt, Sharali Malik, and Christopher E. Anson
Publisher(s): ACS Omega
ISBN/ISSN/DOI: doi.org/10.1021/acsomega.9b02846
ACSTwo monolanthanide-containing polyanions based on monolacunary Keggin germanotungstates [Ln(H2O)nGeW11O39]5- (Ln = Dy, Er, n = 4,3) have been synthesized in simple one-pot synthetic procedure and compositionally characterized in solid state by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. Electronic absorption and emission spectra of the title compounds in solution were also studied. The [DyIII(H2O)4GeW11O39]5- Keggin POM exhibits a slow relaxation of magnetization. The cyclic voltammetry measurements and mass spectrometry were carried out to check the stability of the compounds in solution. Both polyanions prove efficient in the electrocatalytic reduction of nitrite. To our knowledge, this observation establishes the first example of electrocatalysis of nitrite reduction by all inorganic monolanthanide-containing germanotungstates family.
2019|Action number: CA15107
Zinc–dysprosium functionalized amyloid fibrils
Author(s): Stavroula I. Sampani, Youssra K. Al-Hilaly, Sharali Malik, Louise C. Serpell, and George E. Kostakis
Publisher(s): Dalton Transactions
ISBN/ISSN/DOI: doi.org/10.1039/C9DT01134J
RSCThe heterometallic Zn2Dy2 entity bearing partially saturated metal centres covalently decorates a highly ordered amyloid fibril core and the functionalised assembly exhibits catalytic Lewis acid behaviour.
2019|Action number: CA15107
A Long‐Lived Azafullerenyl Radical Stabilized by Supramolecular Shielding with a [10]Cycloparaphenylene
Author(s): Dr. Anastasios Stergiou, Dr. Jérémy Rio, Jan H. Griwatz, Prof. Dr. Denis Arčon, Prof. Dr. Hermann A. Wegner, Dr. Christopher P. Ewels, Dr. Nikos Tagmatarchis
Publisher(s): Angewandte Chemie
ISBN/ISSN/DOI: doi.org/10.1002/anie.201909126
WileyA major handicap towards the exploitation of radicals is their inherent instability. In the paramagnetic azafullerenyl radical C59N., the unpaired electron is strongly localized next to the nitrogen atom, which induces dimerization to diamagnetic bis(azafullerene), (C59N)2. Conventional stabilization by introducing steric hindrance around the radical is inapplicable here because of the concave fullerene geometry. Instead, we developed an innovative radical shielding approach based on supramolecular complexation, exploiting the protection offered by a [10]cycloparaphenylene ([10]CPP) nanobelt encircling the C59N. radical. Photoinduced radical generation is increased by a factor of 300. The EPR signal showing characteristic 14N hyperfine splitting of C59N.⊂ [10]CPP was traced even after several weeks, which corresponds to a lifetime increase of >108. The proposed approach can be generalized by tuning the diameter of the employed nanobelts, opening new avenues for the design and exploitation of radical fullerenes.
2019|Action number: CA15107
Comparison of Two Field-Induced ErIII Single Ion Magnets
Author(s): Irina A. Kühne, Liviu Ungur, Kane Esien, Anthony B. Carter, John D. Gordon, Cameron Pauly, Helge Müller-Bunz, Solveig Felton, Dominic Zerulla, and Grace G. Morgan
Publisher(s): Dalton Transactions
ISBN/ISSN/DOI: doi.org/10.1039/C9DT02434D
RSCWe present the synthesis, magnetic and photophysical properties of four mononuclear LnIII complexes in two isostructural lattices containing GdIII and ErIII. A heptadentate Schiff base ligand and acetate versus trifluorocetate were used to synthesise compleses 1 - 4, where both ErIII complexes 2 and 4 exhibit field-induced SIM behaviour with similar Ueff values (31.6 K for 2and 32.7 K for 4). Ab initio calculations show the structure of the low-lying energy states and highlight that there is significant tunnelling already in the ground doublet state, but the application of a weak magnetic field of 0.05 T is sufficient for the ac magnetic measurements to suppress the tunnelling in the ground state.The calculated main magnetic axes (gZ) in the ground Kramers doublets show small differences between the two ErIII compounds 2 and 4, due to their different ligand field.
2019|Action number: CA15107
Gel actuators based on polymeric radicals
Author(s): Ravindra N. Wickramasinhage, Shailesh K. Goswami, C. John McAdam, Sharali Malik, Lyall R. Hanto, and Stephen C. Moratti
Publisher(s): RSC Advances
ISBN/ISSN/DOI: doi.org/10.1039/C9RA06364A
RSCLow-voltage electrochemical actuation of radical polymer gels has been demonstrated in an organic electrolyte. Polymer gels were prepared by post-modification of active-ester precursor gels with an amine-functionalised radical. A combination of few-layer graphene and multiwall carbon nanotubes gave high conductivity and improved actuation in the gels, with 32% linear actuation. The actuator system showed good stability over at least 10 cycles, showing its promise. The cycle time was several hours due to mass-transport limited transport of ions and solvent into the device.
2019|Action number: CA15107
Biodegradable polyurethane/graphene oxide scaffolds for soft tissue engineering: in vivo behavior assessment
Author(s): Azadeh Motealleh, Siamak Eqtesadi, Fidel H. Perera, Angel L. Ortiz, Pedro Miranda, Antonia Pajares, Rune Wendelbo
Publisher(s): Journal of the Mechanical Behavior of Biomedical Materials
ISBN/ISSN/DOI: doi.org/10.1016/j.jmbbm.2019.05.016
Science Direct13-93 bioglass (BG) scaffolds reinforced with graphene oxide (GO) were fabricated by robocasting (direct-ink-writing) technique. Composite scaffolds with 0–4 vol% content of GO platelets were printed, and then consolidated by pressureless spark plasma sintering at 650 °C. It was found that, despite hampering densification of the bioglass, the addition of GO platelets up to a certain content enhanced the mechanical performance of the 13–93 bioglass scaffolds in terms of strength and, especially, toughness. Best performance was obtained for 2 vol.% GO, which increased strain energy density (toughness) of the scaffolds by ∼894%, and their compressive strength by ∼26%. At higher contents, agglomeration of the nanoplatelets and increased porosity significantly reduced the mechanical enhancement obtained. Implications of the results on the fabrication of novel bioglass scaffolds that may find use in load-bearing bone tissue engineering applications are discussed.
2019|Action number: CA15107
Toward a Predominant Substitutional Bonding Environment in B-Doped Single-Walled Carbon Nanotubes
Author(s): Carlos Reinoso, Claudia Berkmann, Lei Shi, Alexis Debut, Kazuhiro Yanagi, Thomas Pichler, and Paola Ayala
Publisher(s): ACS Omega
ISBN/ISSN/DOI: doi.org/10.1021/acsomega.8b03031
ACSB-doped single-walled carbon nanotubes have been synthesized from sodium tetraphenyl borate and record incorporation percentages of B heteroatoms have been found in this material as-synthesized. However, carbonaceous impurities, besides other byproducts, can still contain boron and therefore exhibit various types of competing bonding environments. To circumvent this issue, which has constantly hindered a conclusive insight to the existing bonding environments in materials alike, we have employed a purification method, which leaves ∼7% at. of B atoms of the total sample composition almost exclusively in the sp2 configuration. This record B substitutional doping, together with the identification of the competing bonding environments are revealed here unambiguously from X-ray photoelectron spectroscopy. The doping level in the purified tubes is about an order of magnitude larger than in other B-doped single-walled tubes even without purification, and brings the state-of-the-art closer to the controlled applicability of this material.
2019|Action number: CA15107
Wake potential in graphene-insulator-graphene composite systems
Author(s): Vito Despoja, Ivan Radović, Lazar Karbunar, Ana Kalinić, and Zoran L. Mišković
Publisher(s): Physical Review B
ISBN/ISSN/DOI: doi.org/10.1103/PhysRevB.100.035443
APSWe study the wake potential produced by an external charged particle that moves parallel to various sy1−Al2O3−sy2 sandwich-like composites, where the system syi (with i=1,2) may be vacuum, pristine graphene, or doped graphene. The effective dielectric function of the composites is obtained using three complementary methods for graphene's electronic response, based on the massless Dirac fermions (MDF) method, the extended hydrodynamic (eHD) model, and the ab initio approach. Three velocity regimes are explored with respect to the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity vF. In the low-velocity regime (below vF), only the transverse optical (TO) phonons in the Al2O3 layer contribute to the wake potential in the surface with sy2 (which is nearest to the charged particle), in a manner that is only sensitive to the composition of that system: if sy2 is vacuum, the TO phonons give rise to intense oscillations in the wake potential, which are strongly suppressed if sy2 is pristine or doped graphene. For intermediate velocities (above vF), the hybridized plasmon-TO phonon modes on both surfaces contribute to the wake potential in the surface with sy2, with the most dominant contribution coming from the hybridized Dirac-like plasmonic modes. In the high-velocity regime (well above vF), the highest-lying hybridized Dirac plasmon gives the dominant contribution to the wake potential, which exhibits a typical V-shaped wave-front pattern that lags behind the charged particle. It is found that the MDF method agrees very well with the results of the ab initio method for small and intermediate velocities. However, in the high-velocity regime, the high-energy π plasmon in graphene introduces new features in the wake potential in the form of fast oscillations, just behind the charged particle. Those oscillations in the wake potential are well described by both the eHD and the ab initio method, proving that the π plasmon indeed behaves as a collective mode.
2019|Action number: CA15107
Biodegradable polyurethane/graphene oxide scaffolds for soft tissue engineering: in vivo behavior assessment
Author(s): Aleksandra Ivanoska-Dacikj, Gordana Bogoeva-Gaceva, Andres Krumme, Elvira Tarasova, Chiara Scalera, Velimir Stojkovski, Icko Gjorgoski, and Trpe Ristoski
Publisher(s): International Journal of Polymeric Materials and Polymeric Biomaterials
ISBN/ISSN/DOI: doi.org/10.1080/00914037.2019.1655754
Taylor and FrancisIn this work, 3D porous electrospun scaffolds based on DegraPol® (DP), a polyester urethane, with different concentrations of graphene oxide (GO) (0.0–2.0 wt%) were obtained. In order to produce scaffolds with increased porosity, solutions of DP and GO were co-electrospun with polyethylene oxide (PEO), which was subsequently removed. The electrospinning resulted in the formation of porous and fibrous scaffolds with superior elasticity. The colloidal Ag was successfully used as a novel method of scaffold sterilization. The results of the in vivo analysis showed scaffold degradation, absence of an inflammatory process and penetration of tissue cells in the scaffold.
2019|Action number: CA15107
Gas Sensing with Iridium Oxide Nanoparticle Decorated Carbon Nanotubes
Author(s): Juan Casanova-Cháfer, Eric Navarrete, Xavier Noirfalise, Polona Umek, Carla Bittencourt, and Eduard Llobet
Publisher(s): Sensors
ISBN/ISSN/DOI: doi.org/10.3390/s19010113
MDPIThe properties of multi-wall carbon nanotubes decorated with iridium oxide nanoparticles (IrOx-MWCNTs) are studied to detect harmful gases such as nitrogen dioxide and ammonia. IrOx nanoparticles were synthetized using a two-step method, based on a hydrolysis and acid condensation growth mechanism. The metal oxide nanoparticles obtained were employed for decorating the sidewalls of carbon nanotubes. Iridium-oxide nanoparticle decorated carbon nanotube material showed higher and more stable responses towards NH3 and NO2 than bare carbon nanotubes under different experimental conditions, establishing the optimal operating temperatures and estimating the limits of detection and quantification. Furthermore, the nanomaterials employed were studied using different morphological and compositional characterization techniques and a gas sensing mechanism is proposed.
2019|Action number: CA15107
Activated graphene as a material for supercapacitor electrodes: effects of surface area, pore size distribution and hydrophilicity
Author(s): Artem Iakunkov, Vasyl Skrypnychuk, Andreas Nordenström, Elizaveta A. Shilayeva, Mikhail Korobov, Mariana Prodana, Marius Enachescu, Sylvia H. Larssond, and Alexandr V. Talyzin
Publisher(s): Physical Chemistry Chemical Physics
ISBN/ISSN/DOI: doi.org/10.1039/C9CP03327K
RSCActivated reduced graphene oxide (a-rGO) is a material with a rigid 3D porous structure and high specific surface area (SSA). Using variation of activation parameters and post-synthesis mechanical treatment we prepared two sets of materials with a broad range of BET (N2) SSA ∼1000-3000 m2 g−1, and significant differences in pore size distribution and oxygen content. The performance of activated graphene as an electrode in a supercapacitor with KOH electrolyte was correlated with the structural parameters of the materials and water sorption properties. a-rGO is a hydrophobic material as evidenced by the negligibly small BET (H2O) SSA determined using analysis of water vapor sorption isotherms. However, the total pore volume determined using water vapor sorption and sorption of liquid water is almost the same as the one found by analysis of nitrogen sorption isotherms. Ball milling is found to provide an improved bulk density of activated graphene and collapse of all pores except the smallest ones (<2 nm). A decrease in the activation temperature from 850 °C to 550 °C is found to result in materials with a narrow micropore size distribution and increased oxygen content. Elimination of mesopores using ball milling or a lower activation temperature provided materials with better specific capacitance despite a significant decrease (by ∼30%) of the BET (N2) SSA. The best gravimetric and volumetric capacitances in KOH electrolyte were achieved not for samples with the highest value of the BET (N2) SSA but for materials with 80-90% of the total pore volume in micropores and an increased BET (H2O) SSA. Comparing the performance of electrodes prepared using rGO and a-rGO shows that a more hydrophilic surface is favorable for charge storage in supercapacitors with KOH electrolyte.
2019|Action number: CA15107
Structural and optical properties of doped amorphous carbon films deposited by magnetron sputtering
Author(s): Liutaurasn Marcinauskasa, Vilius Dovydaitisa, Aleksandras Iljinasa, and Mindaugas Andrulevičiusb
Publisher(s): Thin Solid Films
ISBN/ISSN/DOI: doi.org/10.1016/j.tsf.2019.04.055
Science DirectAmorphous carbon films containing oxygen and bismuth were deposited by direct current magnetron sputtering. The microstructure and optical properties of the films were measured as a function of magnetron sputtering power by atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, UV-VIS-NIR spectrophotometry, and null-ellipsometry. The oxygen concentration in the films was in the range of 19-21 at.%. It was determined that the deposition rate of amorphous carbon films increased and the surface roughness of the films changed from 1.2 nm to 1.7 nm with the increase of magnetron sputtering power. The microRaman analysis demonstrated that the D band shifted to a lower wavenumbers range and the fraction of the sp2 carbon sites decreased as the power increased. X-ray photoelectron spectroscopy revealed that sp3/sp2 ratio in the films varied between 0.74 and 0.98. The optical transmission of the films in the visible region was in the range of 60-90%. The optical band gap and the refractive index of the films depend on the dopant concentration and the sp2 site fraction.
2019|Action number: CA15107
Swelling of graphene oxide membranes in alcohols: effects of molecule size and air ageing
Author(s): Artem Iakunkov, Jinhua Sun, Anastasia Rebrikova, Mikhail Korobov, Alexey Klechikov, Alexei Vorobiev, Nicolas Boulangera, and Alexandr V. Talyzin
Publisher(s): Journal of Materials Chemistry A
ISBN/ISSN/DOI: doi.org/10.1039/C9TA01902B
RSCSwelling of Hummers graphene oxide (HGO) membranes in a set of progressively longer liquid alcohols (methanol to 1-nonanol) was studied using synchrotron radiation XRD after air ageing over prolonged periods of time. Both precursor graphite oxides and freshly prepared HGO membranes were found to swell in the whole set of nine liquid alcohols with an increase of interlayer spacing from ∼7 Å (solvent free) up to ∼26 Å (in 1-nonanol). A pronounced effect of ageing on swelling in alcohols was found for HGO membranes stored in air. The HGO membranes aged for 0.5-1.5 years show progressively slower swelling kinetics, a non-monotonic decrease of saturated swelling in some alcohols and complete disappearance of swelling for alcohol molecules larger than hexanol. Moreover, the HGO membranes stored under ambient conditions for 5 years showed a nearly complete absence of swelling in all alcohols but preserved swelling in water. In contrast, precursor graphite oxide powder showed unmodified swelling in alcohols even after 4 years of ageing. Since the swelling defines the size of permeation channels, the ageing effect is one of the important parameters which could explain the strong variation in reported filtration/separation properties of GO membranes. The time and conditions of air storage require standardization for better reproducibility of results related to performance of GO membranes in various applications. The ageing of GO membranes can be considered not only as a hindrance/degradation for certain applications, but also as a method to tune the swelling properties of HGO membranes for better selectivity in sorption of solvents and for achieving better selective permeability.
2019|Action number: CA15107
Very high boron-doping on single-walled carbon nanotubes from a solid precursor
Author(s): C. Reinoso, L. Shi, O. Domanov, P. Rohringer, T.Pichler, and P. Ayala
Publisher(s): Carbon
ISBN/ISSN/DOI: doi.org/10.1016/j.carbon.2018.08.031
ScienceDirectDespite the tremendous progress on the use of chemical vapor deposition as widespread method for the synthesis of pristine carbon nanotubes, introducing substitutional heteroatoms like boron on the carbon sites imposes several difficulties. The reported precursors used for boron-doped single-walled carbon nanotubes have exclusively been liquid based. Here we show that the use of solid sodium tetraphenylborate, which contains both carbon and boron in its stoichiometry, do not only effectively circumvent the experimental problems reported so far in the synthesis of these materials, but it enables the incorporation of up to 27.5 at.% of boron atoms in the samples as-grown. This percentage corresponds to a total B content, not to substitutional B configuration exclusively. Spectral deconvolution of the B1s signal suggests a 13 at.% of graphitic bonding environment of B within the samples. We propose an alternative method capable of producing B-doped singled-walled tubes with a small diameter distribution (∼0.89 nm to ∼1.9 nm) within a ∼60 °C temperature window.
2019|Action number: CA15107
Non-Isothermal Crystallization Behavior of PEEK/Graphene Nanoplatelets Composites from Melt and Glass States
Author(s): Ángel Alvaredo, María Isabel Martín, Pere Castell, Roberto Guzmán de Villoria, and Juan P. Fernández-Blázquez
Publisher(s): Polymers
ISBN/ISSN/DOI: doi.org/10.3390/polym11010124
MPDIThe effect of the graphene nanoplateletets (GNP), at concentration of 1, 5 and 10 wt %, in Poly ether ether ketone (PEEK) composite crystallization from melt and during cold crystallization were investigated by differential scanning calorimetry (DSC) and real time X-ray diffraction experiments. DSC results revealed a double effect of GNP: (a) nucleating effect crystallization from melt started at higher temperatures and (b) longer global crystallization time due to the restriction in the polymer chain mobility. This hindered mobility were proved by rheological behavior of nanocomposites, because to the increase of complex viscosity, G′, G″ with the GNP content, as well as the non-Newtonian behavior found in composites with high GNP content. Finally, real time wide and small angle synchrotron X-ray radiation (WAXS/SAXS) X-ray measurements showed that GNP has not affected the orthorhombic phase of PEEK nor the evolution of the crystal phase during the crystallization processes. However, the correlation length of the crystal obtained by WAXS and the long period (L) by SAXS varied depending on the GNP content.
2019|Action number: CA15107
Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries
Author(s): Maria K. Rybarczyk, Yunming Li, Mo Qiao, Yong-Sheng Hu, Maria-Magdalena Titirici, and Marek Lieder
Publisher(s): Journal of Energy Chemistry
ISBN/ISSN/DOI: doi.org/10.1016/j.jechem.2018.01.025
Science DirectHere, we report the synthesis of hard carbon materials (RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries. The studies show that the electrochemical properties of RHs are affected by the treatment temperatures, which determine the materials morphology, in particular, their degree of graphitization and extent of continuous channels (nanovoids). The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced anodes. The RHs obtained at 1600 °C deliver the highest reversible capacity of 276 mAh g−1 mainly due to insertion of sodium ions into the nanovoids. This work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.
2018|Action number: CA15107
Oxidized Nanocarbons-Tripeptide Supramolecular Hydrogels: Shape Matters!
Author(s): Daniel Iglesias, Manuel Melle-Franco, Marina Kurbasic, Michele Melchionna, Michela Abrami, Mario Grassi, Maurizio Prato, and Silvia Marchesan
Publisher(s): ACS Nano
ISBN/ISSN/DOI: doi.org/10.1021/acsnano.8b01182
ACSShort peptide hydrogels are attractive biomaterials but typically suffer from limited mechanical properties. Inclusion of other nanomaterials can serve the dual purpose of hydrogel reinforcement and of conferring additional physicochemical properties (e.g., self-healing, conductivity), as long as they do not hamper peptide self-assembly. In particular, nanocarbons are ideal candidates, and their physicochemical properties have demonstrated great potential in nanocarbon-polymer gel biomaterials for tissue engineering or drug delivery. Recently, increasing interest in supramolecular hydrogels drove research also on their enhancement with nanocarbons. However, little is known on the effect of nanocarbon morphology on the self-assembly of short peptides, which are among the most popular hydrogel building blocks. In this work, three different oxidized nanocarbons (i.e., carbon nanotube or CNT as 1D material, graphene oxide sheet or GO as 2D material, and carbon nanohorn or CNH as 3D material) were evaluated for their effects on the self-assembly of the unprotected tripeptide Leu-DPhe-DPhe at physiological conditions. Supramolecular hydrogels were obtained in all cases, and viscoelastic properties were clearly affected by the nanocarbons, which increased stiffness and resistance to applied stress. Notably, self-healing behavior was observed only in the case of CNTs. Tripeptide-nanotube interaction was noted already in solution prior to self-assembly, with the tripeptide acting as a dispersing agent in phosphate buffer. Experimental and in silico investigation of the interaction between peptide and CNTs suggests that the latter acts as nucleation templates for self-assembly and reassembly. Overall, we provide useful insights for the future design of composite biomaterials with acquired properties.
2018|Action number: CA15107
Polymer nanocomposites: Insights on rheology, percolation and molecular mobility
Author(s): Roey Nadiv, Ricardo M. F. Fernandes, Guy Ochbaum, Jing Dai, Matat Buzaglo, Maxim Varenik, Ronit Biton, István Furó, and Oren Regev
Publisher(s): Polymer
ISBN/ISSN/DOI: doi.org/10.1016/j.polymer.2018.07.079
ScienceDirectThe integration of carbon nanotubes (CNTs) into a polymer matrix strongly affects the rheological behavior that in turn may hamper the overall performance of the resulting composite. Research in this topic has focused on bulk rheological properties, while here we employ NMR diffusion experiments to explore the mobility (diffusivity) of epoxy molecules when loaded with CNTs. Rheology and light microscopy indicate percolation of CNT aggregates. Those aggregates cage a substantial amount of epoxy molecules while small angle X-ray scattering indicates some rearrangement of epoxy molecules in the vicinity of the nanotubes. NMR diffusion experiments distinguish between the slow diffusion of the caged molecules and that of the free ones, and relate the fraction of the former to the macroscopic system viscosity. The demonstrated surface-induced slowing-down of diffusion is attributed to strong intermolecular π-π interactions among the epoxy molecules, and between them and the CNT surface. These findings demonstrate the utility of NMR diffusion experiments as an additional method applied to nanocomposites.
2018|Action number: CA15107
Preparation and Electrochemical Performances of Graphene Oxide/PEDOT and Reduced Graphene Oxide/PEDOT Nanofibers and Nanocomposites
Author(s): Deniz Gülercan, İlknur Gergin, and A. Sezai Sarac
Publisher(s): Fibers and Polymers
ISBN/ISSN/DOI: doi.org/10.1007/s12221-018-8393-7
SpringerIn this work, conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was synthesized on the surface of graphene oxide (GO) and reduced graphene oxide (rGO) sheets via in-situ microemulsion polymerization process to achieve graphene oxide-poly(3,4-ethylenedioxythiophene) (GO-PEDOT) and reduced graphene oxide-poly(3,4-ethylenedioxythiophene) (rGO-PEDOT) nanocomposites. Nanofibers of PEDOT, GO-PEDOT, rGO-PEDOT and GO on poly(acrylonitrile-costyrene) (P(AN-co-St)) matrice have also been fabricated due to their high potential in using as electrodes for flexible supercapacitors. As demonstrated by scanning electron microscope, atomic force microscope and spectroscopic techniques, PEDOT has been succesfully synthesized on the surface of the GO and rGO sheets. The SEM results demonstrate that nanofibers have beadless structure with a diameter range less than 300 nm. The electrochemical capacitive properties of the nanofibers were investigated by using electrochemical impedance spectroscopy. The electrochemical measurements reveal that GO enhances capacitive behavior of PEDOT nanofibers more than rGO, but both GO and rGO improve the electrochemical performance of the nanofibers.
2018|Action number: CA15107
Nanotubes from Atlantis: Magnetite in pumice as a catalyst for the growth of carbon nanotubes
Author(s): Sharali Malik
Publisher(s): Polyhedron
ISBN/ISSN/DOI: doi:10.1016/j.poly.2018.06.033
Science DirectNanosized carbon materials such as carbon nanotubes (CNTs) provide the possibility to achieve, in terms of tensile strength and Young’s modulus, incredibly strong materials. Therefore, the fabrication of nanocomposites with CNTs offers the potential for applications in electronics, medicine, defense and aerospace. Furthermore, it has been shown that having branched CNT structures is a promising way forward in terms of providing structures with enhanced mechanical properties. However, in order to realize this, mass production techniques at reasonable costs are needed. One possibility is the chemical vapor deposition (CVD) method which involves the decomposition of a hydrocarbon e.g. benzene, ethylene, methane, etc. over catalytically active metal deposited on or inside a support such as silica, alumina or titania. Here we report a simple and industrially scalable CVD process to manufacture long single-walled carbon nanotubes (SWNTs), branched multi-walled carbon nanotubes (b-MWNTs) and multi-walled carbon nanotubes (MWNTs) using the abundant pumice from the Akrotiri volcanoes on the Greek island of Santorini to catalyze the transformation of the carbon in methane (CH4) into CNT materials.
2018|Action number: CA15107
Extraction of Linear Carbon Chains Unravels the Role of the Carbon Nanotube Host
Author(s): Lei Shi, Kazuhiro Yanagi, Kecheng Cao, Ute Kaiser, Paola Ayala, and Thomas Pichler
Publisher(s): ACS Nano
ISBN/ISSN/DOI: doi:10.1021/acsnano.8b04006
ACSLinear carbon chains (LCCs) have been shown to grow inside double-walled carbon nanotubes (DWCNTs), but isolating them from this hosting material represents one of the most challenging tasks toward applications. Herein we report the extraction and separation of LCCs inside single-walled carbon nanotubes (LCCs@SWCNTs) extracted from a double-walled host LCCs@DWCNTs by applying a combined tip-ultrasonic and density gradient ultracentrifugation (DGU) process. High-resolution transmission electron microscopy, optical absorption, and Raman spectroscopy show that not only short LCCs but clearly long LCCs (LLCCs) can be extracted and separated from the host. Moreover, the LLCCs can even be condensed by DGU. The Raman spectral frequency of LCCs remains almost unchanged regardless of the presence of the outer tube of the DWCNTs. This suggests that the major importance of the outer tubes is making the whole synthesis viable. We have also been able to observe the interaction between the LCCs and the inner tubes of DWCNTs, playing a major role in modifying the optical properties of LCCs. Our extraction method suggests the possibility toward the complete isolation of LCCs from CNTs.
2018|Action number: CA15107
Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems
Author(s): Francesca Cardano, Marco Frasconi, and Silvia Giordani
Publisher(s): Frontiers in Chemistry - Nanoscience
ISBN/ISSN/DOI: doi:10.3389/fchem.2018.00102
Frontiers in ChemistryPhoto-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial's functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field.
2018|Action number: CA15107
Fluorescent single-digit detonation nanodiamond for biomedical applications
Author(s): Nicholas Nunn, Marta d'Amora, Neeraj Prabhakar, Alexander M Panich, Natalya Froumin, Marco D Torelli, Igor Vlasov, Philipp Reineck, Brant Gibson, Jessica M Rosenholm
Publisher(s): Methods and Applications in Fluorescence
ISBN/ISSN/DOI: doi:10.1088/2050-6120/aac0c8
IOP PublishingDetonation nanodiamonds (DNDs) have emerged as promising candidates for a variety of biomedical applications, thanks to different physicochemical and biological properties, such as small size and reactive surfaces. In this study, we propose carbon dot decorated single digit (4-5 nm diameter) primary particles of detonation nanodiamond as promising fluorescent probes. Due to their intrinsic fluorescence originating from tiny (1-2 atomic layer thickness) carbonaceous structures on their surfaces, they exhibit brightness suitable for in vitro imaging. Moreover, this material offers a unique, cost effective alternative to sub-10 nm nanodiamonds containing fluorescent nitrogen-vacancy color centers, which have not yet been produced at large scale. In this paper, carbon dot decorated nanodiamonds are characterized by several analytical techniques. In addition, the efficient cellular uptake and fluorescence of these particles are observed in vitro on MDA-MD-231 breast cancer cells by means of confocal imaging. Finally, the in vivo biocompatibility of carbon dot decorated nanodiamonds is demonstrated in zebrafish during the development. Our results indicate the potential of single-digit detonation nanodiamonds as biocompatible fluorescent probes. This unique material will find application in correlative light and electron microscopy, where small sized NDs can be attached to antibodies to act as a suitable dual marker for intracellular correlative microscopy of biomolecules.
2018|Action number: CA15107
Biodistribution and biocompatibility of passion fruit-like nano-architectures in zebrafish
Author(s): Marta d’Amora, Domenico Cassano, Salvador Pocoví-Martínez, Silvia Giordani, and Valerio Voliani
Publisher(s): Nanotoxicology
ISBN/ISSN/DOI: doi:10.1080/17435390.2018.1498551
Taylor and FrancisPassion fruit-like nano-architectures (NAs) are all-in-one platforms of increasing interest for the translation of metal nanoparticles into clinics. NAs are nature-inspired disassembling inorganic theranostics, which jointly combine most of the appealing behaviors of noble metal nanoparticles with their potential organism excretion. Despite their unique and promising properties, NAs in vivo interactions and potential adverse effects have not yet been investigated. In this study, we employ zebrafish (Danio Rerio) to assess the development toxicity of NAs as well as their uptake and bioaccumulation at different stages of growth. The evaluation of multiple endpoints related to the toxicity clearly indicates that NAs do not induce mortality, developmental defects, or alterations on the hatching rate and behavior of zebrafish. Moreover, the analysis of nanostructures uptake and biodistribution demonstrates that NAs are successfully internalized and present a specific localization. Overall, our results demonstrate that NAs are able to pass through the embryos chorion and accumulate in specific tissues, exhibiting an impressive biocompatibility.
2018|Action number: CA15107
Supercapacitors based on AC/MnO2 deposited onto dip-coated carbon nanofiber cotton fabric electrodes
Author(s): A.J. Paleo, P. Staiti, A. Brigandì, F.N. Ferreira, A.M.Rocha, F. Lufrano
Publisher(s): Energy Storage Materials
ISBN/ISSN/DOI: doi:10.1016/j.ensm.2017.12.013
Science DirectThis work introduces the preparation of flexible carbon composite electrodes based on the top-down approach starting from the dip-coating of carbon nanofibers (CNFs) onto a cotton fabric. On these so-obtained conductive cotton fabrics, further layers of activated carbon and manganese oxide (MnO2) materials were subsequently added to enhance the electrochemical performances of negative and positive electrodes. At the end, two different types of asymmetric supercapacitors (SCs) were assembled with those textile electrodes by using porous paper and Nafion-Na ion-exchange membranes as separators. The different SCs were electrochemically characterized by means of cyclic voltammetry (CV), galvanostatic charge/discharge (G–CD) and electrochemical impedance spectroscopy (EIS). These hybrid carbon-based textile SCs exhibited capacitance performance of 138 and 134 F g–1 with the porous paper and Nafion membrane, respectively, and low self-discharge rates. Furthermore, in this study is considered the combination of two methods (cycling and floating) for studying the long-term durability tests of SCs. In particular, the floating methodology utilizes much more harsh conditions than the common cycling based on G-CD tests at high currents usually discussed in literature. The solid-state (Nafion membrane) hybrid device demonstrated very long durability with 10 K cycles and additional 270 h at a constant voltage of 1.6 V. In summary, the hybrid SCs fabricated with low cost materials and simple methodologies reported in this study showed very promising results for flexible energy storage applications.
2018|Action number: CA15107
Graphene assisted template based LiMn2O4 flexible cathode electrodes
Author(s): Aslihan Guler, Seyma Ozcan Duman, Deniz Nalci, Mustafa Guzeler, Emrah Bulu,t Mehmet Oguz Guler, Hatem Akbulut
Publisher(s): International Journal of Energy Research
ISBN/ISSN/DOI: doi:10.1002/er.4043
Wiley Online LibraryIn this paper, a systematic method has been developed to produce highly flexible and robust graphene/LiMn2O4 (G/LMO) and graphene/LiCr0.05Mn1.95O4 (G/LCMO) free‐standing composite cathode electrodes with increased specific capacity and improved electrochemical capability. Spinel LMO nanorods are synthesized by calcination method followed by a hydrothermal reaction technique. As‐synthesized nanorods were then embedded in a graphene layer which will in turn serve as a self‐standing binder‐free cathode electrode. Spinel LMO and LCMO nanorods with a length of 600 nm and width of 50 nm were then homogenously entrapped and distributed within the layers of conductive graphene structure. This hybrid structure will help to eliminate the use of heavy metal current collectors and electrically resistant binders or even conductive additives. A discharge capacity of 114.5 mAh g−1 is obtained after first cycle and %72 capacity retention is obtained after 250 cycles from G/LCMO freestanding samples. The enhancement in the electrochemical properties is due to the unique freestanding structure of the cathode electrodes.
2018|Action number: CA15107
Graphene composites with dental and biomedical applicability
Author(s): Sharali Malik, Felicite M. Ruddock, Adam H. Dowling, Kevin Byrne, Wolfgang Schmitt, Ivan Khalakhan, Yoshihiro Nemoto, Hongxuan Guo, Lok Kumar Shrestha, Katsuhiko Ariga, and Jonathan P. Hill
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.9.73
Beilstein-JournalsPure graphene in the form of few-layer graphene (FLG) – 1 to 6 layers – is biocompatible and non-cytotoxic. This makes FLG an ideal material to incorporate into dental polymers to increase their strength and durability. It is well known that graphene has high mechanical strength and has been shown to enhance the mechanical, physical and chemical properties of biomaterials. However, for commercial applicability, methods to produce larger than lab-scale quantities of graphene are required. Here, we present a simple method to make large quantities of FLG starting with commercially available multi-layer graphene (MLG). This FLG material was then used to fabricate graphene dental-polymer composites. The resultant graphene-modified composites show that low concentrations of graphene (ca. 0.2 wt %) lead to enhanced performance improvement in physio-mechanical properties – the mean compressive strength increased by 27% and the mean compressive modulus increased by 22%. Herein we report a new, cheap and simple method to make large quantities of few-layer graphene which was then incorporated into a common dental polymer to fabricate graphene-composites which shows very promising mechanical properties.
2018|Action number: CA15107
Absolute determination of optical constants of three transition metals using reflection electron energy loss spectroscopy
Author(s): H. Xu, L. H. Yang, J. Tóth, K. Tőkési, B. Da, and Z. J. Ding
Publisher(s): Journal of Applied Physics
ISBN/ISSN/DOI: doi:10.1063/1.5012013
AIP ScitationThe optical constants, n and k, of three transition metals (Cr, Co, and Pd) were determined from the measured reflection electron energy-loss spectroscopy (REELS) spectra, covering the spectral energy range from visible to vacuum ultraviolet. To do this, a spectral data analysis technique [Xu et al., Phys. Rev. B 95, 195417 (2017)], which combines a sophisticated Monte Carlo simulation for modelling the experimental REELS spectrum and the simulated annealing algorithm for the determination of the true energy loss function (ELF) was adopted. The validity of the obtained ELFs was discussed by comparing with the previous data derived by optical methods and by applying the oscillator strength and the perfect screening-sum rules. Besides, the consistency of the calculated data was evaluated for three in situ measurements for each sample at three primary energies. The complex dielectric function, the refractive index n and the extinction coefficient k were then derived from the obtained ELF via the analytical Kramers-Kronig relation.
2018|Action number: CA15107
Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors
Author(s): Daniel Iglesias, Evgeny Senokos, Belén Alemán, Laura Cabana, Cristina Navío, Rebeca Marcilla, Maurizio Prato, Juan J. Vilatela, and Silvia Marchesan
Publisher(s): ACS Applied Materials and Interfaces
ISBN/ISSN/DOI: doi:10.1021/acsami.7b15973
ACS PublicationsThe assembly of aligned carbon nanotubes (CNTs) into fibers (CNTFs) is a convenient approach to exploit and apply the unique physico–chemical properties of CNTs in many fields. CNT functionalization has been extensively used for its implementation into composites and devices. However, CNTF functionalization is still in its infancy because of the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF assemblies using ozone which was generated in situ from a UV source. In contrast with liquid-based oxidation methods, this gas-phase approach preserves CNTF morphology, while notably increasing its hydrophilicity. The functionalized material is thoroughly characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Its newly acquired hydrophilicity enables CNTF electrochemical characterization in aqueous media, which was not possible for the pristine material. Through comparison of electrochemical measurements in aqueous electrolytes and ionic liquids, we decouple the effects of functionalization on pseudocapacitive reactions and quantum capacitance. The functionalized CNTF assembly is successfully used as an active material and a current collector in all-solid supercapacitor flexible devices with an ionic liquid-based polymer electrolyte.
2017|Action number: CA15107
Synthesis of Nitrogen Doped Single Walled Carbon Nanotubes With Caffeine
Author(s): Filippo Fedi, Oleg Domanov, Paola Ayala, Thomas Pichler
Publisher(s): Physica Status Solidi B
ISBN/ISSN/DOI: doi:10.1002/pssb.201700364
Wiley Online LibraryNitrogen doped single walled carbon nanotubes have many functional benefits. Doping opens the possibility to control the electronic energy levels, surface energy, surface reactivity, and charge carrier density. The additional electron in the outer shell changes the electronic properties of the nanotubes when introduced into the carbon lattice. Here we present the latest findings in the in situ doping during synthesis of single walled carbon nanotubes using caffeine as a precursor of both carbon and nitrogen. A special furnace with two heating elements allowed us to sublimate and decompose the solid precursor. Caffeine allowed us to reach a high doping percentage with high quality nanotubes directly in a one‐step synthesis procedure.
2017|Action number: CA15107
Electrospun carbon nanofiber web electrode: Supercapacitor behavior in various electrolytes
Author(s): Ezgi Ismar, Tolga Karazehir, Murat Ates, A. Sezai Sarac
Publisher(s): The Journal of Applied Polymer Science
ISBN/ISSN/DOI: doi:10.1002/app.45723
Wiley Online LibraryCarbon nanofibers (CNFs) draw great interest due to their noticeable mechanical, electrochemical, and physical properties. In this study, polyacrylonitrile‐based CNFs are obtained via electrospinning technique. Thermal oxidation and low temperature (950 °C) carbonization are applied to the electrospun web in order to achieve CNF. Through the process, Fourier transform infrared‐attenuated total reflectance spectroscopy and Raman spectroscopic results are investigated. The electrochemical properties of the self‐standing CNF webs are examined with electrochemical impedance spectroscopy and cyclic voltammetry. In addition, various electrolyte solutions are studied to investigate the capacitive behavior of CNF webs. Electrolyte type variation has a significant effect on the capacitance results and high capacitance values are achieved in aqueous solution. According to the differing electrolyte types, specific capacitance values (Csp) are recorded between 204 and 149 F g−1 where maximum specific capacitance is obtained in 0.5 M H2SO4 as 204 F g−1
2017|Action number: CA15107
A Molecular Pillar Approach To Grow Vertical Covalent Organic Framework Nanosheets on Graphene: Hybrid Materials for Energy Storage
Author(s): Jinhua Sun, Alexey Klechikov, Calin Moise, Mariana Prodana, Marius Enachescu, Alexandr V. Talyzin
Publisher(s): Angewandte Chemie
ISBN/ISSN/DOI: doi:10.1002/anie.201710502
Wiley Online LibraryHybrid 2D–2D materials composed of perpendicularly oriented covalent organic frameworks (COFs) and graphene were prepared and tested for energy storage applications. Diboronic acid molecules covalently attached to graphene oxide (GO) were used as nucleation sites for directing vertical growth of COF‐1 nanosheets (v‐COF‐GO). The hybrid material has a forest of COF‐1 nanosheets with a thickness of 3 to 15 nm in edge‐on orientation relative to GO. The reaction performed without molecular pillars resulted in uncontrollable growth of thick COF‐1 platelets parallel to the surface of GO. The v‐COF‐GO was converted into a conductive carbon material preserving the nanostructure of precursor with ultrathin porous carbon nanosheets grafted to graphene in edge‐on orientation. It was demonstrated as a high‐performance electrode material for supercapacitors. The molecular pillar approach can be used for preparation of many other 2D‐2D materials with control of their relative orientation.
2017|Action number: CA15107
Carbon nano-onions in biomedical applications: Promising theranostic agents
Author(s): Adalberto Camisasca, Silvia Giordani
Publisher(s): Inorganica Chimica Acta
ISBN/ISSN/DOI: doi:10.1016/j.ica.2017.06.009
Science DirectCarbon nano-onions (CNOs) are an emerging class of nanoparticles which shows great potential in a number of different applications. Carbon nano-materials have been widely explored in biological cell imaging, due to their lack of toxicity, and biosafety. Recently, the rapid development and availability of chemical surface modification methods have made it possible to explore these cage-in-cage structured nanoparticles as novel systems for biological applications. The functionalization of CNOs with different functional groups improves their solubility and biocompatibility, resulting in an increased ability to penetrate into the cells. Moreover, their small size and high surface area allow for the conjugation of different diagnostic and therapeutic agents, opening new avenues in theranostic applications. In this review article, we discuss the latest advances reported by our group regarding the use of CNOs for biomedical applications and our findings confirm their great potentiality as promising platform for novel therapeutic approaches.
2017|Action number: CA15107
Recent advances in smart biotechnology: Hydrogels and nanocarriers for tailored bioactive molecules depot
Author(s): Gesmi Milcovich, Stefania Lettieri, Filipe E. Antunes, Bruno Medronho, Ana C. Fonseca, Jorge F.J. Coelho, Paolo Marizza, Francesca Perrone, Rossella Farra, Barbara Dapas, Gabriele Grassi, Mario Grassi, Silvia Giordani
Publisher(s): Advances in Colloid and Interface Science
ISBN/ISSN/DOI: doi:10.1016/j.cis.2017.05.009
Science DirectOver the past ten years, the global biopharmaceutical market has remarkably grown, with ten over the top twenty worldwide high performance medical treatment sales being biologics. Thus, biotech R&D (research and development) sector is becoming a key leading branch, with expanding revenues. Biotechnology offers considerable advantages compared to traditional therapeutic approaches, such as reducing side effects, specific treatments, higher patient compliance and therefore more effective treatments leading to lower healthcare costs. Within this sector, smart nanotechnology and colloidal self-assembling systems represent pivotal tools able to modulate the delivery of therapeutics. A comprehensive understanding of the processes involved in the self-assembly of the colloidal structures discussed therein is essential for the development of relevant biomedical applications.In this review we report the most promising and best performing platforms for specific classes of bioactive molecules and related target, spanning from siRNAs, gene/plasmids, proteins/growth factors, small synthetic therapeutics and bioimaging probes.
2017|Action number: CA15107
Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications
Author(s): Bertha T. Pérez-Martínez, Lorena Farías-Cepeda, Víctor M. Ovando-Medina, José M. Asua, Lucero Rosales-Marines, and Radmila Tomovska
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.134
Beilstein-JournalsFilm forming, stable hybrid latexes made of methyl metacrylate (MMA), butyl acrylate (BA) and 2-hydroxyethyl methacrylate (HEMA) copolymer reinforced with modified multiwalled carbon nanotubes (MWCNTs) were synthesized by in situ miniemulsion polymerization. The MWCNTs were pretreated by an air sonication process and stabilized by polyvinylpyrrolidone. The presence of the MWCNTs had no significant effect on the polymerization kinetics, but strongly affected the polymer characteristics (Tg and insoluble polymer fraction). The performance of the in situ composites was compared with that of the neat polymer dispersion as well as with those of the polymer/MWCNT physical blends. The in situ composites showed the presence of an additional phase likely due to the strong interaction between the polymer and MWNCTs (including grafting) that reduced the mobility of the polymer chains. As a result, a substantial increase of both the storage and the loss moduli was achieved. At 60 °C, which is above the main transition region of the polymer, the in situ composites maintained the reinforcement, whereas the blends behaved as a liquid-like material. This suggests the formation of a 3D network, in good agreement with the high content of insoluble polymer in the in situ composites.
2017|Action number: CA15107
Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system
Author(s): Vito Despoja, Tijana Djordjević, Lazar Karbunar, Ivan Radović, and Zoran L. Mišković
Publisher(s): Physical Review B
ISBN/ISSN/DOI: doi:10.1103/PhysRevB.96.075433
APS JournalsThe propagator of a dynamically screened Coulomb interaction W in a sandwichlike structure consisting of two graphene layers separated by a slab of Al2O3 (or vacuum) is derived from single-layer graphene response functions and by using a local dielectric function for the bulk Al2O3. The response function of graphene is obtained using two approaches within the random phase approximation (RPA): an ab initio method that includes all electronic bands in graphene and a computationally less demanding method based on the massless Dirac fermion (MDF) approximation for the low-energy excitations of electrons in the π bands. The propagator W is used to derive an expression for the effective dielectric function of our sandwich structure, which is relevant for the reflection electron energy loss spectroscopy of its surface. Focusing on the range of frequencies from THz to mid-infrared, special attention is paid to finding an accurate optical limit in the ab initio method, where the response function is expressed in terms of a frequency-dependent conductivity of graphene. It was shown that the optical limit suffices for describing hybridization between the Dirac plasmons in graphene layers and the Fuchs-Kliewer phonons in both surfaces of the Al2O3 slab, and that the spectra obtained from both the ab initio method and the MDF approximation in the optical limit agree perfectly well for wave numbers up to about 0.1 nm−1. Going beyond the optical limit, the agreement between the full ab initio method and the MDF approximation was found to extend to wave numbers up to about 0.3 nm−1 for doped graphene layers with the Fermi energy of 0.2 eV.
2017|Action number: CA15107
Porous graphite oxide pillared with tetrapod-shaped molecules
Author(s): Jinhua Sun, Francisco Morales-Lara, Alexey Klechikov, Alexandr V. Talyzin, Igor A. Baburin, Gotthard Seifert, Francesca Cardano, Michele Baldrighi, Marco Frasconi, Silvia Giordani
Publisher(s): Carbon
ISBN/ISSN/DOI: doi:10.1016/j.carbon.2017.05.007
Science DirectPorous pillared graphene oxide (GO) materials were prepared using solvothermal reaction of Hummers GO with solution of Tetrakis(4-aminophenyl)methane (TKAm) in methanol. The intercalation of TKAm molecules between individual GO sheets, performed under swelling condition, results in expansion of inter-layer distance of GO from ∼7.5 Å to 13-14 Å. Pillaring GO with bulky, rigid 3D shaped TKAm molecules could be an advantage for the preparation of stable pillared structures compared to e.g. aliphatic or aromatic diamines. Insertion of TKAm molecules into inter-layer space of GO results in formation of interconnected network of sub-nanometer slit pores. The expanded GO structure prepared with optimized GO/TKAm composition shows Specific Surface Area (SSA) up to 660 m2/g which is among the highest reported for GO materials pillared using organic spacers. Modelling of GO structures pillared with TKAm molecules shows that maximal SSA of about 2300 m2/g is theoretically possible for realistic concentration of pillaring molecules in GO interlayers. Hydrogen sorption by pillared GO/TKAm is found to follow standard correlation with SSA both at ambient and liquid nitrogen temperatures with highest uptakes of 1.66 wt% achieved at 77 K and 0.25 wt% at 295 K. Our theoretical simulations show that pillared GO structures do not provide improvement of hydrogen storage beyond well-established physisorption trends even for idealized materials with subnanometer pores and SSA of 2300-3700 m2/g.
2017|Action number: CA15107
Toxicity Assessment of Carbon Nanomaterials in Zebrafish during Development
Author(s): Marta d’Amora, Adalberto Camisasca, Stefania Lettieri and Silvia Giordani
Publisher(s): Nanomaterials
ISBN/ISSN/DOI: doi:10.3390/nano7120414
MPDICarbon nanomaterials (CNMs) are increasingly employed in nanomedicine as carriers for intracellular transport of drugs, imaging probes, and therapeutics agents, thanks to their unique optical and physicochemical properties. However, a better understanding about the effects of CNMs on a vertebrate model at the whole animal level is required. In this study, we compare the toxicity of oxidized carbon nano-onions (oxi-CNOs), oxidized carbon nano-horns (oxi-CNHs) and graphene oxide (GO) in zebrafish (Danio rerio). We evaluate the possible effects of these nanomaterials on zebrafish development by assessing different end-points and exposure periods
2017|Action number: CA15107
Optimal nanomaterial concentration: harnessing percolation theory to enhance polymer nanocomposite performance
Author(s): Roey Nadiv, Michael Shtein, Gal Shachar, Maxim Varenik, and Oren Regev
Publisher(s): Nanotechnology
ISBN/ISSN/DOI: doi:10.1088/1361-6528/aa793e
IOPscienceA major challenge in nanocomposite research is to predict the optimal nanomaterial concentration (ONC) yielding a maximal reinforcement in a given property. We present a simple approach to identify the ONC based on our finding that it is typically located in close proximity to an abrupt increase in polymer matrix viscosity, termed the rheological percolation threshold, and thus may be used as an indicator of the ONC. This premise was validated by rheological and fractography studies of composites loaded by nanomaterials including graphene nanoribbons or carbon or tungsten disulfide nanotubes. The correlation between in situ viscosity, the rheological percolation threshold concentration and the nanocomposite fractography demonstrates the utility of the method.
2017|Action number: CA15107
Palladium Nanoparticles Decorated Graphene Oxide: Active and Reusable Nanocatalyst for the Catalytic Reduction of Hexavalent Chromium(VI)
Author(s): Dr. Metin Celebi, Kadir Karakas, Ilknur Efecan Ertas, Dr. Murat Kaya, Dr. Mehmet Zahmakiran
Publisher(s): Chemistry Select
ISBN/ISSN/DOI: doi:10.1002/slct.201700967
Wiley Online LibraryToday, the catalytic reduction of Cr(VI) to Cr(III) stands one of the most important challenges in the environmental chemistry and catalysis due to highly stable, contaminant and toxic nature of Cr(VI). In this study, we show that a new nanocatalyst system comprised of 3‐aminopropyltriethoxysilane (APTS) stabilized palladium(0) nanoparticles grafted onto the surface of graphene oxide (Pd/GO) efficiently works in the catalytic reduction of Cr(VI) to Cr(III) under mild reaction conditions. Pd/GO nanocatalyst was reproducibly prepared through two‐steps procedure: (i) H2 reduction of Pd(dba)2 (dba=dibenzylideneacetone) in the presence of APTS in THF to synthesize colloidal APTS stabilized palladium(0) nanoparticles and then (ii) the deposition of 3‐aminopropyltriethoxysilane stabilized palladium(0) nanoparticles onto the surface of graphene oxide (GO) by impregnation. The characterization of Pd/GO was carried out by advanced analytical techniques. The summation of the results acquired from these analyses reveals that the formation of well‐dispersed and highly crystalline palladium(0) nanoparticles on the surface of GO. The catalytic performance of the resulting Pd/GO in terms of activity and stability was assessed in the catalytic reduction of Cr(VI) to Cr(III) in aqueous solution in the presence of formic acid (HCOOH) as a reducing agent. We found that Pd/GO nanocatalyst exhibits high activity (TOF=3.6 mol Cr2O72−/mol Pd×min) and reusability (> 90% at 5th reuse) in this catalytic transformation at room temperature.
2017|Action number: CA15107
Far-red fluorescent carbon nano-onions as a biocompatible platform for cellular imaging
Author(s): Stefania Lettieri, Adalberto Camisasca, Marta d'Amora, Alberto Diaspro, Takashi Uchida, Yoshikata Nakajima, Keiichi Yanagisawa, Toru Maekawa and Silvia Giordani
Publisher(s): RSC Advances
ISBN/ISSN/DOI: doi: 10.1039/C7RA09442F
RSC PublishingA new generation of fluorescent carbon nano-onions with enhanced solubility in biological media and bright photoluminescence is reported. The nano-onions functionalized with a water soluble boron dipyrromethene dye emit in the far red spectrum with a high quantum yield (ΦF) and are suitable for high resolution imaging. The nanoparticles are characterized by a variety of different analytical techniques such as thermogravimetric analysis, dynamic light scattering, zeta potential, electron microscopy, Raman, X-ray photoelectron and fluorescence spectroscopies. They are easily internalized by human breast cancer cells (MCF-7) without any significant toxic effects. Moreover, confocal imaging studies show they exhibit a high fluorescence intensity and are localized in the lysosomes at a very low concentration. Our findings confirm the excellent potentialities of these functionalized carbon nanomaterials as biocompatible platform for high resolution biological imaging.
2017|Action number: CA15107
Luminescent supramolecular hydrogels from a tripeptide and nitrogen-doped carbon nanodots
Author(s): Maria C. Cringoli, Slavko Kralj, Marina Kurbasic, Massimo Urban, and Silvia Marchesan
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.157
Beilstein-JournalsThe combination of different components such as carbon nanostructures and organic gelators into composite nanostructured hydrogels is attracting wide interest for a variety of applications, including sensing and biomaterials. In particular, both supramolecular hydrogels that are formed from unprotected D,L-tripeptides bearing the Phe-Phe motif and nitrogen-doped carbon nanodots (NCNDs) are promising materials for biological use. In this work, they were combined to obtain luminescent, supramolecular hydrogels at physiological conditions. The self-assembly of a tripeptide upon application of a pH trigger was studied in the presence of NCNDs to evaluate effects at the supramolecular level. Luminescent hydrogels were obtained whereby NCND addition allowed the rheological properties to be fine-tuned and led to an overall more homogeneous system composed of thinner fibrils with narrower diameter distribution.
2017|Action number: CA15107
Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study
Author(s): İlknur Gergin, Ezgi Ismar, and A. Sezai Sarac
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.161
Beilstein-JournalsIn this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.
2017|Action number: CA15107
Carbon nano-onions as fluorescent on/off modulated nanoprobes for diagnostics
Author(s): Stefania Lettieri, Marta d’Amora, Adalberto Camisasca, Alberto Diaspro, and Silvia Giordani
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.188
Beilstein-JournalsMultishell fullerenes, known as carbon nano-onions (CNOs), have emerged as a platform for bioimaging because of their cell-penetration properties and minimal systemic toxicity. Here, we describe the covalent functionalization of CNOs with a π-extended distyryl-substituted boron dipyrromethene (BODIPY) dye with on/off modulated fluorescence emission activated by an acidic environment. The switching properties are linked to the photoinduced electron transfer (PET) characteristics of the dimethylamino functionalities attached to the BODIPY core. The on/off emission of the fluorescent CNOs is fast and reversible both in solution and in vitro, making this nanomaterial suitable as pH-dependent probes for diagnostic applications.
2017|Action number: CA15107
Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene
Author(s): Naum Naveh, Olga Shepelev and Samuel Kenig
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191
Beilstein-JournalsImpregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.
2017|Action number: CA15107
Freestanding graphene/MnO2 cathodes for Li-ion batteries
Author(s): Şeyma Özcan, Aslıhan Güler, Tugrul Cetinkaya, Mehmet O. Guler and Hatem Akbulut
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191
Beilstein-JournalsDifferent polymorphs of MnO2 (α-, β-, and γ-) were produced by microwave hydrothermal synthesis, and graphene oxide (GO) nanosheets were prepared by oxidation of graphite using a modified Hummers’ method. Freestanding graphene/MnO2 cathodes were manufactured through a vacuum filtration process. The structure of the graphene/MnO2 nanocomposites was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The surface and cross-sectional morphologies of freestanding cathodes were investigated by scanning electron microcopy (SEM). The charge–discharge profile of the cathodes was tested between 1.5 V and 4.5 V at a constant current of 0.1 mA cm−2 using CR2016 coin cells. The initial specific capacity of graphene/α-, β-, and γ-MnO2 freestanding cathodes was found to be 321 mAhg−1, 198 mAhg−1, and 251 mAhg−1, respectively. Finally, the graphene/α-MnO2 cathode displayed the best cycling performance due to the low charge transfer resistance and higher electrochemical reaction behavior. Graphene/α-MnO2 freestanding cathodes exhibited a specific capacity of 229 mAhg−1 after 200 cycles with 72% capacity retention.
2017|Action number: CA15107
Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure
Author(s): Michal Bodik, Anna Zahoranova, Matej Micusik, Nikola Bugarova, Zdenko Spitalsky, Maria Omastova, Eva Majkova, Matej Jergel and Peter Siffalovic
Publisher(s): Nanotechnology
ISBN/ISSN/DOI: doi:10.1088/1361-6528/aa60ef
IOPscienceWe report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm−3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.
2017|Action number: CA15107
Advances and challenges in the field of plasma polymer nanoparticles
Author(s): Andrei Choukourov, Pavel Pleskunov, Daniil Nikitin, Valerii Titov, Artem Shelemin, Mykhailo Vaidulych, Anna Kuzminova, Pavel Solař, Jan Hanuš, Jaroslav Kousal, Ondřej Kylián, Danka Slavínská1, and Hynek Biederman
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.200
Beilstein-JournalsThis contribution reviews plasma polymer nanoparticles produced by gas aggregation cluster sources either via plasma polymerization of volatile monomers or via radio frequency (RF) magnetron sputtering of conventional polymers. The formation of hydrocarbon, fluorocarbon, silicon- and nitrogen-containing plasma polymer nanoparticles as well as core@shell nanoparticles based on plasma polymers is discussed with a focus on the development of novel nanostructured surfaces.
2017|Action number: CA15107
Nanocrystalline diamond protects Zr cladding surface against oxygen and hydrogen uptake: Nuclear fuel durability enhancement
Author(s): Jan Škarohlíd, Petr Ashcheulov, Radek Škoda, Andrew Taylor, Radim Čtvrtlík, Jan Tomáštík, František Fendrych, Jaromír Kopeček, Vladimír Cháb, Stanislav Cichoň, Petr Sajdl, Jan Macák, Peng Xu, Jonna M. Partezana, Jan Lorinčík, Jana Prehradná, Martin Stein
Publisher(s): Scientific Reports
ISBN/ISSN/DOI: doi:10.1038/s41598-017-06923-4
Nature ArticlesIn this work, we demonstrate and describe an effective method of protecting zirconium fuel cladding against oxygen and hydrogen uptake at both accident and working temperatures in water-cooled nuclear reactor environments. Zr alloy samples were coated with nanocrystalline diamond (NCD) layers of different thicknesses, grown in a microwave plasma chemical vapor deposition apparatus. In addition to showing that such an NCD layer prevents the Zr alloy from directly interacting with water, we show that carbon released from the NCD film enters the underlying Zr material and changes its properties, such that uptake of oxygen and hydrogen is significantly decreased. After 100–170 days of exposure to hot water at 360 °C, the oxidation of the NCD-coated Zr plates was typically decreased by 40%. Protective NCD layers may prolong the lifetime of nuclear cladding and consequently enhance nuclear fuel burnup. NCD may also serve as a passive element for nuclear safety. NCD-coated ZIRLO claddings have been selected as a candidate for Accident Tolerant Fuel in commercially operated reactors in 2020.
2017|Action number: CA15107
Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites
Author(s): Claudio Larosa, Niranjan Patra, Marco Salerno, Lara Mikac, Remo Merijs Meri, and Mile Ivanda
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.8.203
Beilstein-JournalsA polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p-xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV–vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV–vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.
2016|Action number: CA15107
Polyyne electronic and vibrational properties under environmental interactions
Author(s): Marius Wanko, Seymur Cahangirov, Lei Shi, Philip Rohringer, Zachary J. Lapin, Lukas Novotny, Paola Ayala, Thomas Pichler, and Angel Rubio
Publisher(s): Physical Review B
ISBN/ISSN/DOI: doi:10.1103/PhysRevB.94.195422
APSRecently the novel system of linear carbon chains inside double-walled carbon nanotubes has extended the length of sp1 hybridized carbon chains from 44 to thousands of atoms [Shi et al., Nat. Mater. 15, 634 (2016)]. The optoelectronic properties of these ultralong chains are poorly described by current theoretical models, which are based on short chain experimental data and assume a constant environment. As such, a physical understanding of the system in terms of charge transfer and van der Waals interactions is widely missing. We provide a reference for the intrinsic Raman frequency of polyynes in vacuo and explicitly describe the interactions between polyynes and carbon nanotubes. We find that van der Waals interactions strongly shift this frequency, which has been neither expected nor described for other intramolecular C-C stretching vibrations. As a consequence of charge transfer from the tube to the chain, the Raman response of long chains is qualitatively different from the known phonon dispersion of polymers close to the Γ point. Based on these findings we show how to correctly interpret the Raman data, considering the nanotube's properties. This is essential for its use as an analytical tool to optimize the growth process for future applications.
2016|Action number: CA15107
Fabrication and characterization of branched carbon nanostructures
Author(s): Sharali Malik, Yoshihiro Nemoto, Hingxuan Guo, Katsuhiko Ariga and Jonathan P. Hill
Publisher(s): Beilstein Journal of Nanotechnology
ISBN/ISSN/DOI: doi:10.3762/bjnano.7.116
Beilstein-JournalsCarbon nanotubes (CNTs) have atomically smooth surfaces and tend not to form covalent bonds with composite matrix materials. Thus, it is the magnitude of the CNT/fiber interfacial strength that limits the amount of nanomechanical interlocking when using conventional CNTs to improve the structural behavior of composite materials through reinforcement. This arises from two wellknown, long standing problems in this research field: (a) inhomogeneous dispersion of the filler, which can lead to aggregation and (b) insufficient reinforcement arising from bonding interactions between the filler and the matrix. These dispersion and reinforcement issues could be addressed by using branched multiwalled carbon nanotubes (b-MWCNTs) as it is known that branched fibers can greatly enhance interfacial bonding and dispersability. Therefore, the use of b-MWCNTs would lead to improved mechanical performance and, in the case of conductive composites, improved electrical performance if the CNT filler was better dispersed and connected. This will provide major benefits to the existing commercial application of CNT-reinforced composites in electrostatic discharge materials (ESD): There would be also potential usage for energy conversion, e.g., in supercapacitors, solar cells and Li-ion batteries. However, the limited availability of b-MWCNTs has, to date, restricted their use in such technological applications. Herein, we report an inexpensive and simple method to fabricate large amounts of branched-MWCNTs, which opens the door to a multitude of possible applications.
2016|Action number: CA15107
Confined linear carbon chains as a route to bulk carbyne
Author(s): Lei Shi, Philip Rohringer, Kazu Suenaga, Yoshiko Niimi, Jani Kotakoski, Jannik C. Meyer, Herwig Peterlik, Marius Wanko, Seymur Cahangirov, Angel Rubio, Zachary J. Lapin, Lukas Novotny, Paola Ayala, and Thomas Pichler
Publisher(s): Nature Materials
ISBN/ISSN/DOI: doi:10.1038/nmat4617
NatureStrong chemical activity and extreme instability in ambient conditions characterize carbyne, an infinite sp1 hybridized carbon chain. As a result, much less has been explored about carbyne as compared to other carbon allotropes such as fullerenes, nanotubes and graphene. Although end-capping groups can be used to stabilize carbon chains, length limitations are still a barrier for production, and even more so for application. We report a method for the bulk production of long acetylenic linear carbon chains protected by thin double-walled carbon nanotubes. The synthesis of very long arrangements is confirmed by a combination of transmission electron microscopy, X-ray diffraction and (near-field) resonance Raman spectroscopy. Our results establish a route for the bulk production of exceptionally long and stable chains composed of more than 6,000 carbon atoms, representing an elegant forerunner towards the final goal of carbyne's bulk production.