![[ Visit Client Website ]](images/banner.png)
Carbon nanotube (CNT) biological applications can be increased by chemical functionalization that allows to change their dispersion but such modification could modify their toxicity. Most of the available studies on functionalized CNT toxicity have been performed on Single Walled Carbon Nanotubes (SWCNTs) and only a few data exist on effects of functionalized MWCNTs. We studied cytotoxicity and genotoxic/oxidative effects of functionalized MWCNT-OH on A549 cells exposed to 1-100 µg/ml.
Methods
Structural characterization of the tested CNTs was performed using energy filtered transmission electron microscopy (EFTEM). Cytotoxicity was evaluated by MTT assay after 24h exposure and LDH assay performed after 4 and 24h exposure. Apoptosis was determined by fluorescence microscopic analysis after 24h exposure. Direct/oxidative DNA damage was evaluated after 2, 4 and 24h by fpg-modified comet assay that allows to detect oxidative DNA damage since the fpg enzyme recognizes and cuts the oxidized DNA purines indirectly allowing the detection of oxidative damage.
Results
Nanotube length varied from 20 nm to 1.7 µm and the outside diameter ranged from 10 nm to 60 nm (mean value 18±1 nm).
After 24h exposure we found viability reduction at the highest concentrations. Significant LDH release was not found neither after 4h nor after 24h exposure. Apoptosis induction was found beginning from 10 µg/ml of MWCNT-OH. A concentration-dependent increase of DNA damage, beginning from 5 µg/ml of MWCNT-OH, was detected at all exposure times. Oxidative DNA damage was not observed.
Discussion
The results demonstrate the capability of MWCNT-OH to reduce cell viability and the induction of apoptotic effect. Moreover, early genotoxic effects of MWCNT-OH also at low concentrations were demonstrated on lung that represents one of the main target organ. This study suggests that further studies on potential health effects of functionalized CNTs are necessary before using them in biological applications.