Functionalization of carbon nanoparticles modulates inflammatory cell recruitment and NLRP3 inflammasome activation.

The inflammatory effects of carbon nanoparticles (NPs) are highly disputed. Here it is demonstrated that endotoxin-free preparations of raw carbon nanotubes (CNTs) are very limited in their capacity to promote inflammatory responses in vitro, as well as in vivo. Upon purification and selective oxidation of raw CNTs, a higher dispersibility is achieved in physiological solutions, but this process also enhances their inflammatory activity. In synergy with toll-like receptor (TLR) ligands, CNTs promote NLRP3 inflammasome activation and it is shown for the first time that this property extends to spherical carbon nano-onions (CNOs) of 6 nm in size. In contrast, the benzoic acid functionalization of purified CNTs and CNOs leads to significantly attenuated inflammatory properties. This is evidenced by a reduced secretion of the inflammatory cytokine IL-1ß, and a pronounced decrease in the recruitment of neutrophils and monocytes following injection into mice. Collectively, these results reveal that the inflammatory properties of carbon NPs are highly dependent on their physicochemical characteristics and crucially, that chemical surface functionalization allows significant moderation of these properties.

Fullerenes, carbon nanotubes, and graphene for molecular electronics.

With the constant growing complexity of electronic devices, the top-down approach used with silicon based technology is facing both technological and physical challenges. Carbon based nanomaterials are good candidates to be used in the construction of electronic circuitry using a bottom-up approach, because they have semiconductor properties and dimensions within the required physical limit to establish electrical connections. The unique electronic properties of fullerenes for example, have allowed the construction of molecular rectifiers and transistors that can operate with more than two logical states. Carbon nanotubes have shown their potential to be used in the construction of molecular wires and FET transistors that can operate in the THz frequency range. On the other hand, graphene is not only the most promising material for replacing ITO in the construction of transparent electrodes but it has also shown quantum Hall effect and conductance properties that depend on the edges or chemical doping. The purpose of this review is to present recent developments on the utilization carbon nanomaterials in molecular electronics.

Electrochemical properties of oxidized carbon nano-onions: DRIFTS-FTIR and raman spectroscopic analyses.

The electrochemical reactions of carboxylic and lactone groups on carbon nano-onions (CNOs) in aqueous solutions result in non-Kolbe products: alcohols, ketones, ethers and epoxides. The anodic/cathodic conversion of ox-CNOs was assessed by Boehm titrations and by Raman and DRIFTS-FTIR (diffuse reflectance infrared Fourier transform spectroscopy). The electrochemical properties of oxidized carbon nano-onions were investigated by cyclic voltammetry in aqueous solutions. The ox-CNOs are electrochemically active as a result of the reduction of the oxygen-containing groups.