Carbon and Metal Quantum Dots toxicity on the microalgae Chlorella pyrenoidosa

• The toxicity of CQDs compared with metal-based QDs was the first time investigated on C. Pyrenoidosa.
• The toxicity of various QDs was investigated more deeply by several parameters.
• The CQDs toxicity was smaller than MQDs, but the CuInS2/ZnS QDs toxicity was the smallest.
• It provides reference value to understand the effects of QDs on ecosystem and utilize them better and safely.

In this report, we investigated the cytotoxicity of two types of quantum dots(QDs) (carbon quantum dots(CQDs): N, S doped CQDs, N doped CQDs, no doped CQDs; metal QDs(MQDs): CdTe QDs, CdS QDs, CuInS2/ZnS QDs) on Chlorella pyrenoidosa(C. Pyrenoidosa) at different concentrations. We compared the toxicity of different QDs on C. Pyrenoidosa through determination of the algal growth inhibition, acute toxicity tests (EC50), Chlorophyll a(Chla) contents, protein contents, the activity of enzymatic and metabolites contents. When C. Pyrenoidosa was treated by various concentrations of QDs, the Chla contents were consistent to the number of algae cells, showing a good dose-response relationship. At the 96 h, the EC50 of N, S doped CQDs, N doped CQDs, no doped CQDs and CdTe QDs, CdS QDs, CuInS2/ZnS QDs were 38.56, 185.83, 232.47, 0.015, 4.88, 459.5 mg/l, respectively. The toxicity order of them was: CuInS2/ZnS QDs