The Shortening of MWNT-SPION Hybrids by Steam Treatment Improves Their Magnetic Resonance Imaging Properties In Vitro and In Vivo

Cabana, Laura et al.Carbon nanotubes (CNTs) have been advocated as promising nanocarriers in the biomedical field. Their high surface area and needle-like shape make these systems especially attractive for diagnostic and therapeutic applications. Biocompatibility, cell internalization, biodistribution, and pharmacokinetic profile have all been reported to be length dependent. In this study, further insights are gotten on the role that the length of CNTs plays when developing novel contrast agents for magnetic resonance imaging (MRI). Two samples of CNTs with different length distribution have been decorated with radio-labeled iron oxide nanoparticles. Despite characterization of the prepared hybrids reveals a similar degree of loading and size of the nanoparticles for both samples, the use of short CNTs is found to enhance the MRI properties of the developed contrast agents both in vitro and in vivo compared to their long counterparts. KeywordsL.C. and M.B. contributed equally to this work. The authors are grateful to Thomas Swan Co. & Ltd for supplying the Elicarb MWNT samples. L.C. acknowledges a CSIC JAE Predoc Fellowship. M.B. is a Marie Curie Fellow. Funding from FP7-ITN Marie-Curie Network programme RADDEL (290023), Biotechnology and Biological Sciences Research Council (BB/J008656/1), Worldwide Cancer Research (12-1054), and Spanish Ministry of Economy and Competitiveness (MAT2014-53500-R and MAT2014-56063-C2-1R) is acknowledged. R.T.M.D. acknowledges funding by The Centre of Excellence in Medical Engineering funded by the Wellcome Trust and EPSRC under Grant No. WT 088641/Z/09/Z. L.C., J.F., and G.T./ ICMAB acknowledge fi nancial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496). K.T.A., G.T, and R.T.M.D. thank the members of the EU COST actions TD1004 (Theranostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging-Guided Drug Delivery) and TD1007 (Bimodal PET-MRI molecular imaging technologies and applications for in vivo monitoring of disease and biological processes) for useful discussions. The XPS data were acquired at the Laboratorio de Microscopías Avanzadas (LMA) – Instituto de Nanociencia de Aragón (INA) (Spain).Peer reviewe

The magnetic non-hydrostatic shallow-water model

Funding: DGD would like to thank the Leverhulme Trust for support received during a Research Fellowship. SMT was supported by funding from the European Research Council (ERC) under the EU's Horizon 2020 research and innovation programme (grant agreement D5S-DLV-786780).We consider the dynamics of a set of reduced equations describing the evolution of a magnetised, rotating stably stratified fluid layer, atop a stagnant dense, perfectly conducting layer. We consider two closely related models. In the first, the layer has, above it, relatively light fluid where the magnetic pressure is much larger than the gas pressure, and the magnetic field is largely force-free. In the second model, the magnetic field is constrained to lie within the dynamical layer by the implementation of a model diffusion operator for the magnetic field. The model derivation proceeds by assuming that the horizontal velocity and the horizontal magnetic field are independent of the vertical coordinate, whilst the vertical components in the layer have a linear dependence on height. The full system comprises evolution equations for the magnetic field, horizontal velocity and height field together with a linear elliptic equation for the vertically integrated non-hydrostatic pressure. In the magneto-hydrostatic limit, these equations simplify to equations of shallow-water type. Numerical solutions for both models are provided for the fiducial case of a Gaussian vortex interacting with a magnetic field. The solutions are shown to differ negligibly. We investigate how the interaction of the vortex changes in response to the magnetic Reynolds number Rm, the Rossby deformation radius LD, and a Coriolis buoyancy frequency ratio f/N measuring the significance of non-hydrostatic effects. The magneto-hydrostatic limit corresponds to f/N→0.Publisher PDFPeer reviewe

Encapsulation of two-dimensional materials inside carbon nanotubes : towards an enhanced synthesis of single-layered metal halides

The unique properties of two-dimensional (2D) nanomaterials make them highly attractive for a wide range of applications. As a consequence, several top-down and bottom up approaches are being explored to isolate or synthesize single-layers of 2D materials in a reliable manner. Here we report on the synthesis of individual layers of several 2D van der Waals solids, namely CeI, CeCl, TbCl and ZnI by template-assisted growth using carbon nanotubes as directing agents, thus proving the versatility of this approach. Once confined, the metal halides can adopt different structures including single-layered metal halide nanotubes, which formation is greatly enhanced by increasing the temperature of synthesis. This opens up a new strategy for the isolation of individual layers of a wide variety of metal halides, a family of 2D materials that has been barely explored

Exploring different doping mechanisms in thermoelectric polymer/ carbon nanotube composites

This work compares various methods to prepare polymer/carbon nanotube (CNT) composites for thermoelectric applications, focusing on the different doping mechanisms. We first look at the general trends observed in the Seebeck coefficient and power factor for a large number of composites as a function of electrical conductivity. Then we discuss two methods of nitrogen doping the carbon nanotubes in these composites, namely either during synthesis, or afterwards by ammonolysis. Finally, we discuss doping of the carbon nanotubes through charge transfer from the polymer counterpart, including photo-induced switching of the majority carrier type. As a general remark, we note that processability is negatively influenced by some doping procedures. Best results were achieved for unfunctionalized single-walled carbon nanotubes with a high content of semiconducting CNT species.The authors would like to thank Prof. Michael L. Chabinyc, Prof. Christian Müller and Prof. Alejandro R. Goñi for useful discussions. We are grateful to John D. Craddock, Prof. Matthew C. Weisen- berger and Prof. John E. Anthony for providing the n-MWCNTs. The authors would also like to acknowledge financial support from the Ministerio de Economía y Competitividad of Spain through projects CSD2010–00044 (Consolider NANOTHERM), MAT2015- 70850-P and MAT2014-53500-R; and the European Research Council (ERC) under grant agreement no. 648901. S. Sandoval acknowledges a contract though PIE 201660E013 and P. Kankla the Development and Promotion of Science and Technology Talents Project (DPST). We are grateful to Thomas Swan Co. Ltd for supplying Elicarb1 SWCNTs.Peer reviewe

Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

Altres ajuts: this work was supported by the Spanish National Research Council under the Contract Nos. 200960I015, 200860I211.Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs

Design of antibody-functionalized carbon nanotubes filled with radioactivable metals towards a targeted anticancer therapy

Spinato, Cinzia et al.In the present work we have devised the synthesis of a novel promising carbon nanotube carrier for the targeted delivery of radioactivity, through a combination of endohedral and exohedral functionalization. Steam-purified single-walled carbon nanotubes (SWCNTs) have been initially filled with radioactive analogues (i.e. metal halides) and sealed by high temperature treatment, affording closed-ended CNTs with the filling material confined in the inner cavity. The external functionalization of these filled CNTs was then achieved by nitrene cycloaddition and followed by the derivatization with a monoclonal antibody (Cetuximab) targeting the epidermal growth factor receptor (EGFR), overexpressed by several cancer cells. The targeting efficiency of the so-obtained conjugate was evaluated by immunostaining with a secondary antibody and by incubation of the CNTs with EGFR positive cells (U87-EGFR+), followed by flow cytometry, confocal microscopy or elemental analyses. We demonstrated that our filled and functionalized CNTs can internalize more efficiently in EGFR positive cancer cells.The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007–2013/ under REA grant agreement no 290023 (RADDEL). This work was partly supported by the Centre National de la Recherche Scientifique (CNRS), by the Agence Nationale de la Recherche (ANR) through the LabEx project Chemistry of Complex Systems (ANR-10-LABX-0026_CSC) and by the International Center for Frontier Research in Chemistry (icFRC). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). KCL acknowledges support from WCR. The authors are grateful to Thomas Swan & Co. Ltd for providing Elicarb® SWCNTs. MM, MK and EP work has been done as a part of PhD program in Materials Sciences at UAB.Peer reviewe

Structure of inorganic nanocrystals confined within carbon nanotubes

There are many examples in which the cavities of carbon nanotubes have been filled with a variety of compounds. Unprecedented structures compared to those of the same material in the bulk are observed, such as low dimensional crystals. Such encapsulated materials can have unusual properties that differ from those of the bulk material. The scope of this review is to give a brief approach to the different nanostructures formed after encapsulation of inorganic compounds within the inner cavities of carbon nanotubes. The confined materials can take the form of one-dimensional anowires, nanoclusters or even inorganic nanotubes

Charge transfer in steam purified arc discharge single walled carbon nanotubes filled with lutetium halides

Altres ajuts: we also acknowledge financial support from the Czech science foundation (20-08633X), MEYS project (LTC18039). The authors also acknowledge the assistance provided by the Research Infrastructures Nano-EnviCz (Project No. LM2015073) supported by the Ministry of Education, Youth and Sports of the Czech Republic and the project Pro-NanoEnviCz (Reg. No. CZ.02.1.01/0.0/0.0/ 16_013/0001821) supported by the Ministry of Education, Youth and Sports of the Czech Republic and the European Union - European Structural and Investments Funds in the frame of Operational Programme Research Development and Education.In the present work, the effect of doping on electronic properties in bulk purified and filled arc-discharge single-walled carbon nanotubes samples is studied for the first time by in situ Raman spectroelectrochemical method. A major challenge to turn the potential of SWCNTs into customer applications is to reduce or eliminate their contaminants by means of purification techniques. Besides, the endohedral functionalization of SWCNTs with organic and inorganic materials (i.e. metal halides) allows the development of tailored functional hybrids. Here, we report the purification and endohedral functionalization of SWCNTs with doping affecting the SWCNTs. Steam-purified SWCNTs have been filled with selected lutetium(iii) halides, LuCl, LuBr, LuI, and sealed using high-temperature treatment, yielding closed-ended SWCNTs with the filling material confined in the inner cavity. The purified SWCNTs were studied using TGA, EDX, STEM and Raman spectroscopy. The lutetium(iii) halide-filled SWCNTs (LuX@SWCNTs) were characterized using STEM, EDX, Raman spectroscopy and in situ Raman spectroelectrochemistry. It was found that there is a charge transfer between the SWCNTs and the encapsulated LuX (X = Cl, Br, I). The obtained data testify to the acceptor doping effect of lutetium(iii) halides incorporated into the SWCNT channels, which is accompanied by the charge transfer from nanotube walls to the introduced substances

Filling Single-Walled Carbon Nanotubes with Lutetium Chloride : A Sustainable Production of Nanocapsules Free of Nonencapsulated Material

Filled carbon nanotubes are of interest for a wide variety of applications ranging from sensors to magnetoelectronic devices and going through the development of smart contrast and therapeutic agents in the biomedical field. In general, regardless of the method employed, bulk filling of carbon nanotubes results in the presence of a large amount of external nonencapsulated material. Therefore, further processing is needed to achieve a sample in which the selected payload is present only in the inner cavities of the nanotubes. Here, we report on a straightforward approach that allows the removal of nonencapsulated compounds in a time efficient and environmentally friendly manner, using water as a "green" solvent, while minimizing the residual waste. The results presented herein pave the way toward the production of large amounts of high-quality closed-ended filled nanotubes, also referred to as carbon nanocapsules, readily utilizable in the foreseen applications