Occurrence, behavior, and ecotoxicity of quantum dots in aquatic environments

Abstract

Quantum dots (QDs), as a new type of nanomaterial, are widely used in the biomedical, electronic, and energy fields. Due to their special physicochemical properties and compositions, the harmful effects of QDs on living organisms have attracted global attention, but only a few studies have addressed their long-term ecological consequences. Studies on the ecotoxicology of QDs still lack a systematic overview of their individual toxicity to aquatic organisms and an in-depth understanding of the ecological consequences. In this study, we reviewed the relevant studies in recent decades to 1) assess the distribution of QDs in aquatic environments; 2) summarize the possible environmental behaviors of QDs in aquatic environments; and 3) systematically discuss the ecotoxicity of QDs to aquatic organisms from molecular to individual levels and the possible long-term ecological consequences caused by QDs. Toxicological studies showed that QDs could reach many parts of the body after entering the organism, and some of them could be excreted through their excretory system. However, QDs that remain in the organism could cause reduced enzyme activity, dysregulated gene expression, DNA strand breakage, apoptosis, and metabolic disorders and even affect reproduction and survival. Subsequently, the effects of QDs on individual organisms may threaten the development of populations, communities, and whole ecosystems, as evidenced by the transfer of QDs between different trophic levels, reduced productivity of aquatic ecosystems, and effects on biogeochemical cycles. Finally, the shortcomings of the current study are discussed, and suggestions for future research are provided.