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

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

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

Description of the Protocols for Randomized Controlled Trials on Cancer Drugs Conducted in Spain (1999-2003)

To describe the characteristics of randomized controlled clinical trials (RCT) on cancer drugs conducted in Spain between 1999 and 2003 based on their protocols. We conducted an observational retrospective cohort study to identify the protocols of RCTs on cancer drugs authorized by the Agencia Española del Medicamento y Productos Sanitarios (AEMPS) (Spanish Agency for Medicines and Medical Devices) during 1999-2003. A descriptive analysis was completed and the association between variables based on the study setting and sponsorship were assessed. We identified a total of 303 protocols, which included 176,835 potentially eligible patients. Three-quarter of the studies were internationally-based, 61.7% were phase III, and 76.2% were sponsored by pharmaceutical companies. The most frequently assessed outcomes were response rate (24.7%), overall survival (20.7%), and progression-free survival (14.5%). Of all protocols, 10.6% intended to include more than 1000 patients (mean: 2442, SD: 2724). Compared with their national counterparts, internationally-based studies were significantly larger (p<0.001) and were more likely to implement centralized randomization (p<0.001), blinding of the intervention (p<0.001), and survival as primary outcome (p<0.001). Additionally, most internationally-based studies were sponsored by pharmaceutical companies (p<0.01). In a high percentage of protocols, the available information was not explicit enough to assess the validity of each trial. Compared to other European countries, the proportion of Spanish cancer drugs protocols registered at (7%) was lower. RCTs on cancer drugs conducted in Spain between 1999 and 2003 were more likely to be promoted by pharmaceutical companies rather than by non-profit national groups. The former were more often part of international studies, which generally had better methodological quality than national ones. There are some worldwide on-going initiatives that aim to increase the transparency and quality of future research

Nanosecond Laser-Assisted Nitrogen Doping of Graphene Oxide Dispersions

N-doped reduced graphene oxide (RGO) has been prepared in bulk form by laser irradiation of graphene oxide (GO) dispersed in an aqueous solution of ammonia. A pulsed Nd:YAG laser with emission wavelengths in the infrared (IR) 1064 nm, visible (Vis) 532 nm, and ultraviolet (UV) 266 nm spectral regions was employed for the preparation of the N-doped RGO samples. Regardless of the laser energy employed, the resulting material presents a higher fraction of pyrrolic nitrogen compared to nitrogen atoms in pyridinic and graphitic coordination. Noticeably, whereas increasing the laser fluence of UV and Vis wavelengths results in an increase in the total amount of nitrogen, up to 4.9 at. % (UV wavelength at 60 mJ cm fluence), the opposite trend is observed when the GO is irradiated in ammonia solution through IR processing. The proposed laser-based methodology allows the bulk synthesis of N-doped reduced graphene oxide in a simple, fast, and cost efficient manner

Synthesis of dry SmCl₃ from Sm₂O₃ revisited. Implications for the encapsulation of samarium compounds into carbon nanotubes

Samarium is a rare-earth metal with several applications in materials science. It is used in organic chemistry as a reducing agent and it is the active payload in samarium-153 lexidronam, a drug being used for palliative treatment of bone metastases. Recently, the encapsulation of samarium compounds into the cavities of carbon nanotubes has attracted interest for the development of the next generation of radiopharmaceuticals. In the present study, we explore different routes to afford the encapsulation of samarium based materials into single-walled carbon nanotubes. Anhydrous samarium(III) chloride, despite being highly hygroscopic, raises as an excellent candidate to achieve a high filling efficiency. We provide a protocol that allows the synthesis of anhydrous samarium(III) chloride starting from samarium(III) oxide in a fast and simple manner. Synchrotron X-ray powder diffraction confirmed the crystallinity and purity of the synthesized SmCl₃

Synthesis of PbI₂ single-layered inorganic nanotubes encapsulated within carbon nanotubes

The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures

Lateral-flow assays for bovine paratuberculosis diagnosis

Mycobacterium avium subsp. paratuberculosis (MAP) causes bovine paratuberculosis (PTB). PTB is responsible for significant economic losses in dairy herds around the word. PTB control programs that rely on testing and culling of test-positive cows have been developed. Current diagnostics, such as ELISA for detecting MAP antibodies in serum samples and PCR detecting MAP DNA in feces, have inadequate sensitivity for detecting subclinical animals. Innovative “omics” technologies such as next-generation sequencing (NGS) technology-based RNA-sequencing (RNA-Seq), proteomics and metabolomics can be used to find host biomarkers. The discovered biomarkers (RNA, microRNAs, proteins, metabolites) can then be used to develop new and more sensitive approaches for PTB diagnosis. Traditional approaches for measuring host antibodies and biomarkers, such as ELISAs, northern blotting, quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR), cDNA microarrays, and mass spectrometry are time-consuming, expensive, and sometimes exhibit poor sensitivity. With the rapid development of nanotechnology, low-cost monitoring devices for measuring antibodies against MAP proteins in point-of-care (POC) settings have been developed. Lateral flow assays (LFAs), in particular, are thought to be appropriate for the on-site detection of antibodies to MAP antigens and/or host biomarkers. This review aims to summarize LFAs that have recently been developed to accurately detect antibodies against MAP antigens, as well as the benefits that host biomarkers linked with MAP infection give to PTB diagnosis. The identification of these novel biomarkers could be the basis for the development of new LFAs. The dairy industry and producers are likely to benefit from reliable and rapid technologies capable of detecting MAP infection in situ to establish a quick and sensitive PTB diagnosis