Behavioural response as a reliable measure of acute nanomaterial toxicity in zebrafish larvae exposed to a carbon-based versus a metal-based nanomaterial

Abstract

Production, use and disposal of products containing nanomaterials can lead to an increased presence of these particles in the environment and exposure to the organisms found there. It is therefore becoming increasingly necessary to develop methods for screening these materials for possible toxic effects. Behavioural analyses have proven to be a dependable and accurate measure of ecotoxicological risk factors. The aim of the current study was to investigate the toxicological effect of two types of nanomaterials (carbon- and metal-based) on zebrafish larvae. Individual larvae, seven days post fertilisation, were transferred to wells on 24-well plates containing OECD ISO fish media. Sections of the plate to be exposed were randomly arranged and incrementally dosed with sublethal stock concentrations of suspended CdTe (functionalised cadmium-tellurium) quantum dots (QDs) and nanodiamonds (NDs). Subsequently, the 24-well plate was loaded into a DanioVision® system and the behaviour of the larvae recorded for 12 h. The recordings were then analysed using Noldus™ EthoVision® software. Exposure to QDs affected various locomotor and behaviour endpoints over time, i.e. distance travelled, swimming speed, mobility and acceleration states. A significant increase in locomotor activity, coupled with erratic and hyperactive swimming bouts, were observed in zebrafish larvae exposed to QDs, a nanomaterial associated with cadmium  dissolution toxicity. However, behaviour remained largely unaffected in zebrafish exposed to NDs. The results support the use of zebrafish in acute toxicological studies, as a result of its sensitivity to environmental toxins. Their relatively small size permits the use of multi-well plates to allow  rapid, high-throughput screening of pollutants.

Keywords: Danio rerio, exposure, functionalised cadmium-tellurium quantum dots, locomotion,  nanodiamonds, Noldus™ EthoVision® software, pollutants