Multi-walled carbon nanotubes, natural organic matter, and the benthic diatom Nitzschia palea: "a sticky story".
Different effects of multi-walled carbon nanotubes (MWCNTs) on the freshwater diatom Nitzschia palea were examined. MWCNTs used in this study (MWCNT) were dispersed either by sonication without (MWCNT sonicated) or with a realistic concentration (10 mg L(-1)) of Natural Organic Matter (MWCNT+NOM). A pocket-size device was designed to distinguish shading effect (using MWCNT suspensions as external filters) from total exposure effect of MWCNT sonicated and MWCNT+NOM on benthic algae. This study demonstrates that cell division was strongly inhibited after a 48 h exposure to MWCNT+NOM compared to MWCNT sonicated. This device did not yield a quantifiable contribution of shading to growth inhibition of MWCNT sonicated and below 10 mg L(-1) of MWCNT+NOM. In all cases, neither lethal effects nor drops in photosynthetic quantum yield were observed. After a 6-d exposure, a complete growth recovery was observed for all conditions except at the highest concentration of MWCNT+NOM. Different microscopic approaches using carbohydrates markers revealed the strong affinity between MWCNT and extracellular polymeric substances (EPS) produced by N. palea. These seem to constitute a defensive mechanism against MWCNT.
EcoLab (Laboratoire d'Ecologie Fonctionnelle et Environnement), ENSAT, INP, UPS, Université de Toulouse; UMR CNRS 5245 , Castanet Tolosan , France .
Laurent
L
Verneuil
Jérôme
J
Silvestre
Florence
F
Mouchet
Emmanuel
E
Flahaut
Jean-Charles
JC
Boutonnet
Floriane
F
Bourdiol
Tifania
T
Bortolamiol
David
D
Baqué
Laury
L
Gauthier
Eric
E
Pinelli
D001704:Biopolymers / Q000096:biosynthesis*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D017377:Diatoms / Q000187:drug effects* / Q000502:physiology*; D037742:Nanotubes, Carbon / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology*; D018675:Toxicity Tests / Q000379:methods; D014873:Water Pollutants / Q000633:toxicity*
D001704:Biopolymers; D037742:Nanotubes, Carbon; D014873:Water Pollutants
Algae; extracellular polymeric substances; nano-ecotoxicology; nanoparticles; toxicity