The Toxicity Assessment Of Fluorescent CdTe Quantum Dots And Silicon Nanoparticles On Caenorhabditis Elegans

The past decades have witnessed giant advancement of nanomaterials. Semiconductor quantum dots(QDs) and fluorescent silicon nanoparticles(SiNPs), recognized as typical fluorescent nanomaterials, have wide-ranging biological applications owning to their attractive optical properties. The widespread applications of fluorescent nanomaterials have triggered increasing concerns about their biosafety. Caenorhabditis elegans(C. elegans) has been widely employed as a model organism to study the biosafety of nanomaterials due to its excellent merits. For example, C. elegans allows studies of biological processes with subcellular resolution in the context of the whole-organism physiological environment, and the evolutionally conserved genetic background of C. elegans also guarantees that results obtained from C. elegans studies are highly valuable for human-related studies. Consequently, in this work, we employ C. elegans as the model organism to systematically investigate the biosafety of CdTe QDs and fluorescent SiNPs.Firstly, here we systematically investigate the behavior and toxicity of Cd Te QDs of three different sizes in C. elegans at both the systemic and the subcellular level. Specifically, we observe clear size-dependent distribution and toxicity of the CdTe QDs in the digestive tract. Short-term exposure of QDs only inhibits development and leads to acute toxicity on C. elegans, yet incurring no lasting, irreversible damage. In contrast, chronic exposure of QDs severely inhibits development and shortens life span. Consequently, unlike in vitro cultured cells, C. elegans can withstand the disturbance over a short period. If QDs are retained within certain somatic cells for too long, the toxicity exerted upon the organisms would be irreversible. Subcellular analysis reveals that endocytosis and nutrition storage are disrupted by CdTe QDs, which likely account for the severe deterioration in growth and longevity. Our work reveals that CdTe QDs invasion disrupts key subcellular processes in live organisms, and may cause permanent damage to the tissues and organs over long-term retention. Our findings provide invaluable information for safety evaluations of QDs-based applications.Secondly, we employ the model organism C. elegans and mammalian cells to investigate the effect of SiNPs on autophagy induction. Specifically, there is no formation of autophagosomes when the cells or worms are exposed to SiNPs. In addition, we show that the transcription of autophagy-related genes maintain unchanged, and the expression of autophagy-related genes are not upregulated after the treatment of SiNPs. Moreover, SiNPs have no significant effect on the formation of autophagosomes in cells after exposure to different time points. Real-time tracking the formation of autophagosomes in C. elegans further indicates that the formation of autophagosomes are not induced by SiNPs. In summary, we put forward a preliminary conclusion that SiNPs may not induce autophagy on cells and C. elegans at the concentration of ensuring the imaging. Our studies offer invaluable information regarding the relationship between autophagy and SiNPs.