Versatile carbon dots with superoxide dismutase-like nanozyme activity and red fluorescence for inflammatory bowel disease therapeutics

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a chronic and recurrent disease that seriously affects the life quality of patients. Oxidative stress induced by abnormally high levels of reactive oxygen species (ROS) in the colon is the characteristic and pathogenic factor of IBD. Therefore, eliminating ROS in the inflamed colon is a promising approach for the treatment of IBD. This study employed a carbon dots (C-dots) nanozyme derived from glutathione and biotin via a solvothermal method to relieve IBD. We found that the resulting C-dots nanozyme owned both favorable superoxide dismutase (SOD) enzymatic activity and fluorescence capability. In vitro experiments showed that the C-dots could eliminate the excessive ROS to protect cells against oxidative stress and reduce the expression of pro-inflammatory cytokines, such as TNF-α, IL-6, and IL-1β. In IBD mice models (for both colitis and Crohn's), we found that administration of the C-dots with great biocompatibility could effectively alleviate the inflammation of the colon, including the reduction of the colon length, the damaged epithelium, the infiltration of inflammatory cells, and the overexpression of the pro-inflammatory cytokines. Moreover, the preferable fluorescence property of the C-dots could be used for in vivo imaging. Overall, this C-dots nanozyme, without appreciable systemic toxicity, represents a novel therapeutic approach for IBD and is expected to achieve long-term inflammatory remission.