Chronic Toxicity of Double-Walled Carbon Nanotubes to Three Marine Organisms: Influence of Different Dispersion Methods

Abstract

Aim: Double-walled carbon nanotubes (DWNTs) are found in a variety of consumer products, but there are no ecotoxicity data of DWNTs into marine organisms. Materials & methods: Chronic toxicity of DWNTs was investigated with the diatom Thalassiosira pseudonana, copepod Tigriopus japonicus and medaka Oryzias melastigma. DWNTs were dispersed using sonication (so-DWNTs) and stirring (st-DWNTs) for comparison. Results: The median aggregation size (0.89 µm2) of so-DWNTs was smaller than that of st-DWNTs (21.8 µm2). Exposure to DWNTs led to growth inhibition of T. pseudonana with EC50s of 1.86 and 22.7 mg/l for so- and st-DWNTs, respectively. Population growth of T. japonicus was reduced to 0.1 mg/l for so-DWNTs and 10 mg/l for st-DWNTs. Growth inhibition in O. melastigma was observed at 10 mg/l for so-DWNTs but not for st-DWNTs. Conclusion: Given that so-DWNTs are consistently significantly more toxic than st-DWNTs, dispersion method and size of aggregations should be considered in DWNT toxicity testing.

Carbon Nanotubes in Electronics: Background and Discussion for Waste-Handling Strategies

“…In addition to this modeled concentration, an unknown amount of naturally occurring CNTs and fullerenes are found in glaciers, volcano ash and soil [46]. Even though the estimated amount of CNTs in circulation does not appear to present any ecotoxicological threat to the environment, this is strongly contrasted by findings in aquatic species [34,36].…”

“…CNTs have also been shown to interfere with living organisms, to pose health risks and cause genotoxicity, mortality and cellular damage as aerosol or hydrosol particles [28][29][30][31][32][33][34][35][36][37][38]. At the critical end of the spectrum, recent aquatic studies on CNTs show induced organ pathology disturbance of respiratory function in rainbow trout, as well as causing terminal effects on mono-cellular aquatic organisms [34,36]. Furthermore, severe damage to mice has been shown [5,[31][32][33]35,[37][38][39], where more violent reactions than asbestos and carbon black were observed [38].…”

Chloroquine-enhanced gene delivery mediated by carbon nanotubes

“…For this purpose, DWCNTs were selected because of their versatility, as both their external wall and inner tube can be functionalized for loading with different compounds, and because of their no toxicity at concentrations potentially useful for biomedical applications. Compared to common sources, they present the advantage of being perfectly characterized in terms of morphology and purity, as well as toxicity thanks to earlier studies [3,17,18,19,20]. They also offer a better chemical and mechanical stability as compared to single-walled carbon nanotubes (SWCNTs) and thus represent the optimal choice in terms of drug/container weight ratio.…”

“…As it can be seen, as the chloroquine loading increases the transfection efficiency increases (chloroquine loading are in the order (24) < (20) < (22) corresponding to opened < oxidized < raw DWCNTs). However, as explained in section 3.5, sample (20) showed the lowest cytotoxicity and therefore, it was selected as optimum. In addition, these DWCNT showed no cytotoxicity at the concentration levels needed for optimum gene delivery (see Supplementary Material section S4).…”

“…In addition, these DWCNT showed no cytotoxicity at the concentration levels needed for optimum gene delivery (see Supplementary Material section S4). In conclusion, chloroquine-loaded oxidized DWCNTs coated with PEI (sample (20) were selected as optimum gene delivery system. The overall approach of this methodology is illustrated in Figure 7.…”