Conformational and functional effects of MPA‐CdTe quantum dots on SOD: Evaluating the mechanism of oxidative stress induced by quantum dots in the mouse nephrocytes

Abstract

The application of quantum dots (QDs) is restricted by the biosafety issue. QDs contribute to the adverse effects of organisms probably because of the ability to induce oxidative stress via changing the activity of antioxidant enzyme, for example, superoxide dismutase (SOD). But the underlying molecular mechanisms still remain unclear. This study investigated the harmful effects of oxidative stress induced by mercaptopropionic acid capped CdTe QDs (MPA-CdTe QDs) on the mouse primary nephrocytes as well as the structure and function of SOD molecule and explored the underlying molecular mechanism. After 24-hour MPA-CdTe QD exposure, the activation level of extracellular regulated protein kinase (ERK) signaling pathway and cysteinyl-directed aspartate-specific proteases (Caspases) significantly increased, which led to the increasing level of reactive oxygen species (ROS) and cell apoptosis; the group pretreated with ROS scavenger N-acetyl-L-cysteine (NAC) significantly reduced the apoptotic cell percentage, indicating that ROS played a critical role in QD-induced cytotoxicity. Further molecular experiments showed that the interacting processes between the MPA-CdTe QDs and SOD were spontaneous which changed the conformation, secondary structure of SOD. The interaction significantly resulted in the tightening of polypeptide chains and the shrinkage of SOD, leading to the inhibition of molecular SOD activity. This study demonstrates the adverse effects of QDs, revealing their potential risk in biomedical applications.

Molecular toxicity of nanoplastics involving in oxidative stress and desoxyribonucleic acid damage

“…SOD plays a key role for keeping the balance between intrinsic antioxidant defenses and ROS in cell. The change of SOD activity can generally indicate that excessive ROS needs to be eliminated for avoiding oxidative damage . As shown in Figure 1, the activity of SOD increases depending on NPS addition, which suggests that the increase of ROS concentration induced the increase of SOD activity to main the balance of intrinsic antioxidant defenses.…”