Free cadmium ions released from CdTe-based nanoparticles and their cytotoxicity on Phaeodactylum tricornutum

The risk of nanoparticles (NPs) to organisms and the environment has become more noticeable alongside their rapid applications in many fields. The release of Cd(2+) from CdTe-based NPs (CdTe-NPs), an important class of engineered nanomaterials, is one of the possible factors responsible for the cytotoxicity of these NPs. Based on the same CdTe core, CdTe/CdS, CdTe/ZnS and CdTe/SiO(2) NPs were synthesized and their Cd(2+) release rates were carefully studied based on dialysis using inductively coupled plasma mass spectrometry (ICPMS). Results obtained indicated that the Cd(2+) release rates of the CdTe-NPs decreased in the order CdTe (8.78 ng mL(-1) mg(-1) h(-1)) > CdTe/CdS (2.63) > CdTe/SiO(2) (0.89) > CdTe/ZnS (0.72). Phaeodactylum tricornutum was used as a model diatom for evaluating the cytotoxicity of the CdTe-NPs. Results obtained from the CdTe-NPs exposure experiments together with ICPMS and fluorescence microscopy studies suggested that the cytotoxicity of the CdTe-NPs increased along with the increase in their Cd(2+) release rates. Effective coating materials such as ZnS and SiO(2) for the CdTe core significantly reduced the cytotoxicity of CdTe.