Objective: 

Carbon nanotubes (CNT) are repetitive structures made of carbon atoms. They can be single-walled (SWCNT) or multi-walled (MWCNT) structures. Various applications have been proposed for CNT. However, their safety for human administration is a controversial subject. In vitro studies have pointed oxidative stress and inflammation as mechanisms involved in their cytotoxic effects, while there are only few in vivo studies, using especially pulmonary models. Based on our previous experience regarding SWCNT, our aim was to evaluate the capacity of functionalized MWCNT to generate oxidative stress after ip administration in rats.

Methods: 

MWCNT were characterized by SEM, TEM and Raman spectroscopy. For in vivo administration, the dispersed MWCNT solutions were obtained after single strand DNA (ss-DNA) functionalization through sonication. The concentration of ss-DNA-MWCNTs solution was estimated by UV-Vis-NIR spectroscopy. The presence of MWCNT in blood and liver was detected by Raman spectroscopy at seriate time points after their administration. The oxidative stress was evaluated in dynamics (1h, 3h, 6h, 24 h, 48 h and 6 days) after the administration, both in blood and liver. We also assessed hepatic enzymes, markers of inflammation and angiogenesis.

Results: 

The most evident alterations were produced in blood of MWCNT treated animals comparatively with controls at 1 hour interval (malondialdehyde 3.01±0.22 vs 1.65± 0.15 nmol/ml; reduced glutathione 16.55 ± 1.15 vs 21.5± 1.2 nmol/ml) and in liver at 3 hours interval.

Conclusions: 

Our results demonstrate that ss-DNA-MWCNT produce oxidative stress both in blood and liver, with a transient pattern, and with a maximum at 1 hour after their ip administration.