The characterisation of the behaviour and gill toxicity of CdS/CdTe quantum dots in rainbow trout (Oncorhynchus mykiss)

The increasing commercial application of nanomaterials is raising concerns about their potential release to aquatic environments. The purpose of this study was to examine the behaviour in freshwater of capped CdS/CdTe quantum dots and the sublethal effects on gills of rainbow trout. Rainbow trout (Oncorhynchus mykiss) were exposed to increasing concentrations of CdS/CdTe or dissolved cadmium (CdSO4) for 48 h at 15°C. The initial Cd and Te concentration in the aquarium water and size fractionation were determined. After the exposure period, the gills were analysed for labile Cd content, changes in lactate and pyruvate, total and redox status of metallothioneins (MT), lipid peroxidation, protein chaperones of the heat shock protein (Hsp) 72 family and ubiquitin conjugates. QDs were mostly between 6.8 and 25 nm suggesting aggregates. Significant increases in total and metal-binding MT, gill lactate and pyruvate levels and Hsp 72 proteins were observed while ubiquitin protein conjugates were significantly decreased by the QDs only with dissolved Cd, LPO and lactate/pyruvate ratio were not affected by the QDs. A discriminant function analysis of the biomarker responses revealed that colloidal and dissolved Cd differed significantly from each other, suggesting different modes of action.