Interaction between foodborne carbon dots and cadmium mediates synergistic escalation of toxicity: Bioaccumulation-driven oxidative stress aggravates colonic injury

Food-borne carbon dots (FCDs) are ubiquitous nanoparticles in food thermal processing, which might co-occur with persistent environmental pollutants and pose potential health risks. Cadmium (Cd) is a common harmful heavy metal pollutant in the environment. However, the interaction between FCDs and Cd and the biotoxic effects of the resultant complexes (FCDs-Cd) on organisms remain almost entirely unexplored. Herein, TEM, FTIR, XPS, and ITC were utilized to analyze the interaction between FCDs and Cd. Based on this, zebrafish and mice were employed as model animals to explore the exposure of FCDs-Cd. The results illustrated that FCDs spontaneously interacted with Cd to form FCDs-Cd. Furthermore, exposure to FCDs-Cd caused 2.73-fold higher mortality in zebrafish and exacerbated developmental abnormalities. Moreover, accumulation of FCDs-Cd was found in the liver, kidney, and intestine of mice, which led to redox homeostasis imbalance and reactive oxygen species overproduction. Furthermore, FCDs-Cd caused 4-fold higher Cd accumulation in the colon than the Cd group, resulting in more pronounced damage. Transcriptome analysis further revealed that the FCDs-Cd may induce colonic injury in mice via activating the Syk/Btk/NF-κB pathway. This study provides novel perspectives for assessing the health risks of endogenous nanoparticles and heavy metals.