The acute pulmonary toxicity in mice induced by multiwall carbon nanotubes, benzene, and their combination.

Carbon nanotubes (CNTs) have been synthesized and produced on large scale for their wide application. They have high absorption ability to organic contaminants (such as benzene) and can form CNTs-benzene combination with benzene. In this article, the acute pulmonary toxicity, induced by multiwall carbon nanotubes (MWCNTs), benzene, and their combination, was studied by administrating the three test materials into mice lungs via intratracheal instillation. The biochemical parameters in bronchoalveolar lavage fluid (BALF) and pathological lesions in lungs were used as endpoints to evaluate the pulmonary toxicity of the three test materials at 3-day and 7-day postexposure, respectively. After the mice were intratracheally instilled with MWCNTs, benzene and MWCNTs-benzene combination at doses of 6.67 mg/kg, 2.67 mg/kg, and 9.34 mg/kg (containing 6.67 mg/kg MWCNTs and 2.67 mg/kg benzene), the total protein, alkaline phosphatase (ALP), acid phosphatase (ACP), and lactate dehydrogenase (LDH) in BALF and pathological lesions in lungs were examined. At 3-day postexposure, MWCNTs induced obvious pulmonary toxicity and benzene only induced slight pulmonary toxicity, whereas their combination induced very severe pulmonary toxicity. At 7-day postexposure, MWCNTs and benzene did not induce pulmonary toxicity individually, whereas their combination still induced severe pulmonary toxicity. These data indicated that, at the instilled doses in this experiment, the MWCNTs can alone induce acute pulmonary toxicity in mice and the benzene does not induce pulmonary toxicity, but the pulmonary toxicity of MWCNTs is enhanced after they form MWCNTs-benzene combination with low dose of benzene. The enhanced pulmonary toxicity may be due to the change of MWCNTs aggregation ability after benzene is adsorbed on them.

Pulmonary responses to polyhydroxylated fullerenols, C(60)(OH)(x).

Although many scientists have been attracted by polyhydroxylated fullerenols for their radical-scavenging and antioxidant ability in vivo and in vitro and their potential use as a drug or for drug delivery, there is little information on their pulmonary toxicological properties. The aim of this study was to investigate the effect of polyhydroxylated derivatives of fullerene on Sprague-Dawley rats after intratracheal instillation. Polyhydroxylated fullerenols [C(60)(OH)(x), x = 22, 24] were administered intratracheally (1, 5 or 10 mg per rat). Following 3-day exposures, the lungs of the rats were assessed using bronchoalveolar lavage fluid biomarkers and a pathological evaluation of lung tissue. Exposures to 1 mg per rat did not induce adverse pulmonary toxicity, while the two other doses induced cell injury effect, oxidative/nitrosative stress and inflammation, showing that C(60)(OH)(x) produced responses in a dose-dependent manner. The dosage of C(60)(OH)(x) retained in lung and the ensuing aggregation might be the main factor in the process. Our results might shed light on the possible use of C(60)(OH)(x) as an inhaled drug.

[Fluorescence properties of C60-glucocorticoids].

C60 and its derivatives have become a research hotspot because of their unique structures, physical and chemical properties. The fluorescence properties of C60 and its derivatives are an important research embranchment of the fullerene science field. In the present paper the fluorescence properties of C60-glucocorticoids were firstly investigated. When excited with the wavelength of 350 nm at room temperature, C60-glucocorticoids displayed the fluorescence emission in chloroform at 447 nm. The sixty carbon atoms of C60 molecule are equivalent, belonging to the Ih group, and presenting high symmetry. It is difficult to observe the fluorescence of C60 under the same condition because of the high symmetry of C60 molecule. The fluorescence emission of C60-glucocorticoids is probably due to the decrease in the high symmetry of C60 molecule. Moreover, the fluorescence emission at 447 nm of a series of concentrations (10-13 micromol x L(-1)) of C60-glucocorticoids chloroform solutions excited at 350 nm was determined, and the result indicated that the C60-glucocorticoids in chloroform could quench itself's fluorescence intensity. Within the concentration range of 10-64 micromol x L(-1), the fluorescence intensity increased along with the accretion of the concentration. When the concentration of C60-glucocorticoids was greater than 64 micromol x L(-1) the fluorescence intensity decreased gradually.

Comparative study of pathological lesions induced by multiwalled carbon nanotubes in lungs of mice by intratracheal instillation and inhalation.

The pathological lesions induced by multiwalled carbon nanotubes (MWCNTs) in bronchi and alveoli of mice were studied by intratracheal instillation and inhalation. In instillation groups, the dose was 0.05 mg MWCNTs/mouse. Similar size clumps of MWCNTs were distributed in bronchi and alveoli. The clumps led to inflammation to the lining wall of bronchi and severe destruction to alveolar netted structure around them. In the inhalation groups, the mice were exposed to aerosolized MWCNTs with mean concentration of 32.61 mg/m(3), the intralung deposition dose were roughly 0.07, 0.14, and 0.21 mg in the 8-day group, 16-day group, and 24-day group, respectively. Most of aggregations of MWCNTs in the alveoli were smaller than that in bronchi. The aggregations induced proliferation and thickening of alveolar walls. With the exception of these moderate pathological lesions, the general alveolar structure was still remained. The preliminary study demonstrated a difference in lung pathological lesions induced by instilled MWCNTs and inhaled ones, which may be due to the different size and distribution of aggregations of MWCNTs in lung.

[Selective adsorption of multi-walled carbon nanotubes with liquiritin and isoliquiritin].

Selective adsorption of active ingredients liquiritin and isoliquiritin from Glycyrrhiza uralensis Fisch with multi-walled carbon nanotubes (MWNTs) has been studied. Distribution coefficients of liquiritin between ethanol solvent and r-MWNTs or o-MWNTs in 293K is 37.5 and 43.3, while the distribution coefficients of isoliquiritin between ethanol solvent and r-MWNTs or o-MWNTs is 717 and 1080, respectively. It was indicated that the distribution coefficient of isoliquiritin adsorbed by MWNTs was much larger than that of liquiritin, and oxidation treatment of MWNTs could obviously enhance their adsorption ability. The possible reasons that MWNTs can selectively adsorb isoliquiritin other than liquiritin were discussed on the bases of molecular structure of the active ingredients and their interaction with nanotubes.

Reactions of fullerenes with reactive methylene organophosphorus reagents: efficient synthesis of organophosphorus group substituted C60 and C70 derivatives.

Treatment of C70 with cycloalkylaminomethylenebisphosphonates in the presence of NaH gave corresponding C70 dimers 1 in good yield, while the methanofullerenes, C70>CH(PO3Et2) (3) and C70>C(PO3Et2)2 (4) or C60>CH(PO3Et2) (5) and C60>C(PO3Et2)2 (6), were obtained, respectively, by the reaction of C70 or C60 with tetraethyl methylenediphosphonate in the presence of NaH. Diethyl cyanomethylphosphonate reacted with C60 or C70 under similar conditions to afford C60>C(PO3Et2)CN (7) and C70>C(PO3Et2)CN (8). Furthermore, the presence of weak electronic interactions between two fullerene cages of fullerene dimers was demonstrated by cyclic voltammetry. A radical mechanism was proposed for the formation of the fullerene derivatives on the basis of the ESR studies.