The Importance of the Purification Step and the Characterization of the Products in the Synthesis of Carbon Nanodots

In the synthesis of carbon nanodots (CNDs), the critical step of the purification from the starting materials and unwanted side products is faced. In the exciting race toward new and interesting CNDs, this problem is often underestimated, leading to false properties and erroneous reports. In fact, on many occasions, the properties described for novel CNDs derive from impurities not completely eliminated during the purification process. Dialysis, for instance, is not always helpful, especially if the side products are not soluble in water. In this Perspective, the importance of the purification and characterization steps, in order to obtain solid reports and reliable procedures, is emphasized

Microwave-assisted one-step synthesis of water-soluble manganese-carbon nanodot clusters

Using metal coordination to assemble carbon nanodots (CND) into clusters can enhance their photophysical properties for applications in sensing and biomedicine. Water-soluble clusters of CNDs are prepared by one-step microwave synthesis starting from ethylenediaminetetraacetic acid, ethylenediamine and MnCl2 & BULL;4H2O as precursors. Transmission electron microscopy and powder X-Ray diffraction techniques indicate that the resulting clusters form spherical particles of 150 nm constituted by amorphous CNDs joined together with Mn ions in a laminar crystalline structure. The nanomaterial assemblies show remarkable fluorescence quantum yields (0.17-0.20) and magnetic resonance imaging capability (r1 = 2.3-3.8 mM-1.s-1). In addition, they can be stabilized in aqueous solutions by phosphate ligands, providing a promising dual imaging platform for use in biological systems

Wire Up on Carbon Nanostructures! How To Play a Winning Game

Carbon nanotubes and graphene possess a unique extended \u3c0-system that makes them stand out among carbon nanostructures. The resulting electronic properties enable electron or charge flow along one or two directions, respectively, thus offering the opportunity to connect electronically different entities that come into contact, be they living cells or catalytic systems. Using these carbon nanostructures thus holds great promise in providing innovative solutions to address key challenges in the fields of medicine and energy. Here, we discuss how chemical functionalization of these carbon nanostructures is a crucial tool to master their properties and deliver innovation

Recent advances of graphene-based hybrids with magnetic nanoparticles for biomedical applications

The utilization of graphene-based nanomaterials combined with magnetic nanoparticles offers key benefits in the modern biomedicine. In this minireview, we focus on the most recent advances in hybrids of magnetic graphene derivatives for biomedical applications. We initially analyze the several methodologies employed for the preparation of graphene-based composites with magnetic nanoparticles, more specifically the kind of linkage between the two components. In the last section, we focus on the biomedical applications where these magnetic-graphene hybrids are essential and pay special attention on how the addition of graphene improves the resulting devices in magnetic resonance imaging, controlled drug delivery, magnetic photothermal therapy and cellular separation and isolation. Finally, we highlight the use of these magnetic hybrids as multifunctional material that will lead to a next generation of theranostics

Chiral Carbon Nanodots Can Act as Molecular Catalysts in Chemical and Photochemical Reactions

In this work, a microwave synthesis followed by a simple purification process produces a new type of chiral Carbon Nanodots (CNDs). These CNDs are soluble in organic solvents, exhibit amino groups on their surface and display interesting absorption and emission properties along with mirror image profiles in the electronic circular dichroism spectrum. All these features set the stage for CNDs to act as multifunctional catalytic platforms, able to promote diverse chemical transformations. In particular, the outer shell composition of CNDs was instrumental to carry out organocatalytic reactions in an enantioselective fashion. In addition, the redox and light-absorbing properties of the material are suitable to drive photochemical processes. Finally, the photoredox and organocatalytic activations of CNDs were exploited at the same time to promote a cross-dehydrogenative coupling. This work demonstrates that CNDs can be used as catalysts to promote multiple reactivities, previously considered exclusive domain of molecular catalysts

Into the carbon: A matter of core and shell in advanced electrocatalysis

Electrocatalysis, particularly related to fuel cell applications or other processes related to sustainability, has been steadily advanced by the design of new hierarchical materials involving two or more phases. One particularly appealing type of structure features metal species confined within carbon layers. These materials combine the benefits of the two components, which often work in synergy. However, given the intrinsic catalytic activity of carbon and the fact that the metal may be chemically inaccessible, in many cases, which of the two phases is the truly active site is not fully clear. Particularly for pure core–shell systems, where the metal is completely covered by carbon, the identification of the specific task of each component is not trivial. Many reported works on this type of bi-component catalyst are speculative in this regard. It is important for catalyst development that future studies on these systems will include a thorough cross-check of the reactivity aspects by means of combination of suitable techniques or experiments to unravel probable mechanisms and that assumptions are avoided.Electrocatalysis, particularly related to fuel cell applications or other processes related to sustainability, has been steadily advanced by the design of new hierarchical materials involving two or more phases. One particularly appealing type of structure features metal species confined within carbon layers. These materials combine the benefits of the two components, which often work in synergy. However, given the intrinsic catalytic activity of carbon and the fact that the metal may be chemically inaccessible, in many cases, which of the two phases is the truly active site is not fully clear. Particularly for pure core–shell systems, where the metal is completely covered by carbon, the identification of the specific task of each component is not trivial. Many reported works on this type of bi-component catalyst are speculative in this regard. It is important for catalyst development that future studies on these systems will include a thorough cross-check of the reactivity aspects by means of combination..

Primary microglia maintain capacity to function despite internalisation and intracellular loading with carbon nanotubes

Biomedical applications of functionalised carbon nanotubes (f-CNTs) for imaging as well as drug or gene delivery in the brain have recently gained interest. Several studies have demonstrated the potential of f-CNTs to offer treatment options for neurological conditions with success. However, there is also evidence that f-CNTs accumulate preferentially within microglial cells when introduced in the brain. Considering the key immunological role of these cells in the brain and the limited knowledge regarding the interaction of CNTs with microglial cells, it is imperative to understand whether accumulation of CNTs in microglial cells can alter their physiological functions or trigger pro-inflammatory signalling. The aim of the present study was to investigate the basic physiological functions of isolated primary microglial cells over time, following their exposure to multi-walled carbon nanotubes functionalized via different surface chemistries. We rationalized that some chemical strategies may be more deleterious for microglial cell functions than others. We used rat primary microglial cells that can be maintained in cell culture for a long period of time without undergoing cell division. Cell viability, phagocytosis, migration, and pro-inflammatory factor release were studied over one month, following a single exposure to a non-cytotoxic concentration of three different f-CNTs (carboxylated, aminated and both carboxylated and aminated). We show that f-CNTs do not induce inflammation and do not affect the basic functions of microglial cells under these conditions. Importantly, this was the case from day 1 to day 28 post-exposure, even though microglial cells had internalized f-CNTs in subcellular compartments and retained the nanotube load in their cytoplasm over time.This work was supported by the European Commission, under the FP-7 Marie Curie actions (Career Development Intra-European Fellowship, PIEF-GA-2010-276051, project NANONEUROHOP). AB wishes to thank the CNRS financial support from PICS (Project for International Scientific Cooperation). MP, as the recipient of the AXA Chair, is grateful to the AXA Research Fund for financial support. MP was also supported by the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), by the University of Trieste and by Diputación Foral de Gipuzkoa program Red (101/16)