The effects of functionalization of carbon nanotubes on toxicological parameters in mice

Carbon nanotubes (CNTs) have emerged as a new class of multifunctional nanoparticles in biomedicine, but their multiple in vivo effects remain unclear. Also, the impact of various functionalization types and duration of exposures are still unidentified. Herein, we report a complete toxicological study to evaluate the effects of single- and multiwalled carbon nanotubes (SWCNTs and MWCNTs) with either amine or carboxylic acid (COOH) surface functional groups. The results showed that significant oxidative stress and the subsequent cell apoptosis could be resulted in both acute and, mainly, in chronic intravenous administrations. Also, male reproductive parameters were altered during these exposures. The amino-functionalized CNTs had more toxic properties compared with the COOH functionalized group, and also, in some groups, the multiwalled nanotubes were more active in eliciting cytotoxicity than the single-walled nanotubes. Interestingly, the SWCNTs-COOH had the least alterations in most of the parameters. Evidently, it is concluded that the toxicity of CNTs in specific organs can be minimized through particular surface functionalizations.

PAMPS-graft-Ni3Si2O5(OH)4 multiwalled nanotubes as a novel nano-sorbent for the effective removal of Pb(ii) ions

PAMPS-g-Ni3Si2O5(OH)4 NTs for the effective removal of Pb(ii).

Carbon Nanotube and Cellulose Nanocrystal Hybrid Films

The use of cellulose nanocrystals (CNC) in high performance coatings is attractive for micro-scale structures or device fabrication due to the anisotropic geometry, however CNC are insulating materials. Carbon nanotubes (CNT) are also rod-shaped nanomaterials that display high mechanical strength and electrical conductivity. The hydrophobic regions of surface-modified CNC can interact with hydrophobic CNT and aid in association between the two anisotropic nanomaterials. The long-range electrostatic repulsion of CNC plays a role in forming a stable CNT and CNC mixture dispersion in water, which is integral to forming a uniform hybrid film. At concentrations favorable for film formation, the multiwalled nanotubes + CNC mixture dispersion shows cellular network formation, indicating local phase separation, while the single-walled nanotube + CNC mixture dispersion shows schlieren texture, indicating liquid crystal mixture formation. Conductive CNT + CNC hybrid films (5–20 μm thick) were cast on glass microscope slides with and without shear by blade coating. The CNT + CNC hybrid films electrical conductivity increased with increasing CNT loadings and some anisotropy was observed with the sheared hybrid films, although to a lesser extent than what was anticipated. Percolation models were applied to model the hybrid film conductivity and correlate with the hybrid film microstructure.

Improved dielectric properties of polymer-based composites with carboxylic functionalized multiwalled carbon nanotubes

The biggest issues in the preparation of carbon nanotube (CNT)-reinforced composites reside in efficient dispersion of CNT into polymer matrix. In our work, a simple acid treatment method was adopted to obtain carboxylic functionalized multiwalled nanotubes (MWNTs), thus improving the dispersion of CNT and interaction between particles and polymer matrix. X-ray photoelectron spectroscopy and Fourier transform infrared showed that the carboxylic groups were introduced onto the surface of MWNTs. The Raman spectroscopy showed that the amorphous carbon materials and impurities decreased after acid treatment. The electrical and dielectric properties of the Polyamide-11 (PA11)-based composites filled with pristine multiwalled nanotubes (p-MWNTs) and carboxylic functionalized multiwalled nanotubes (c-MWNTs) were investigated. The biggest dielectric constant of PA11/c-MWNTs composites, which was about twice as high as that of PA11/p-MWNTs composites at room temperature and 103 Hz (345–610), was obtained, accompanied by a lower dielectric loss. The formation of abundant microcapacitors and improved interfacial polarization effect by improving the dispersion of MWNTs in the composites via carboxylic functionalization was the main reason for the excellent dielectric properties of PA11/c-MWNTs composites.