Qualitative and quantitative analysis of accumulation and biodistribution of polystyrene nanoplastics in zebrafish (Danio rerio) via artificial freshwater

The artificial freshwater exposure pathway to plastic-nanomaterials is not only one of the essential uptake and bioaccumulation pathways in aquatic organisms, but it is also one technique to analyze the transmission risk of plastic-nanoparticles in the aquatic environment. To address this concern, we developed a new method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and simultaneously used it to investigate qualitatively and quantitatively the accumulation and biodistribution of PSN in zebrafish tissues. Qualitative analysis confirmed the presence of PSN in the tissues of zebrafish that were exposed, via artificial freshwater, to different concentrations of PSN (1-20 mg L-1) for 20 days. Quantitative analysis revealed that the accumulation of PSN in zebrafish increased in a tissue-, time- and concentration dependent manner. Results showed that the intestine, liver and gill accumulated the highest amount of PSN (275.01, 260.32, and 215.16 & mu;g g(-1) wet weight, respectively), while the muscle and brain significantly accumulated the lowest quantity of PSN (85.71, and 58.23 & mu;g g(-1) wet weight, respectively). The uptake kinetic parameters showed that in the exposure medium of low concentration (1-5 mg L-1), the steady state in different tissues needed a longer time than those with high concentration (10-20 mg L-1). Our results are essential for a full perception of PSN fate via the artificial freshwater exposure route, and environmental and ecological risk assessment of plastic nanoparticles.