N-acetylcysteine-derived Carbon Dots for Free Radical Scavenging in Intervertebral Disc Degeneration.

Intervertebral disc degeneration (IVDD) is associated with oxidative stress induced reactive oxygen species (ROS) dynamic equilibrium disturbance. Nanozymes, as nanomaterials with enzyme-like activity, are able to regulate intro-cellular ROS levels. In this study, a new carbon dots nanozyme, N-acetylcysteine-derived carbon dots (NAC-CDs), was developed and proved to be an ideal antioxidant and anti-senescent agent in IVDD management. The results confirmed the NAC-CDs have satisfactory biocompatibility and strong superoxide dismutase (250 U mg -1 ), catalase, glutathioneperoxidase-like activity and total antioxidant capacity. Then, the powerful free radical scavenging and antioxidant ability of NAC-CDs were demonstrated in vitro as observing the reduced ROS in H 2 O 2 induced senescent nucleus pulposus cells (NPCs), in which the elimination efficiency of toxic ROS was more than 90%. NAC-CDs also maintained mitochondrial homeostasis and suppressed cellular senescence, subsequently inhibited the expression of inflammatory factors in NPCs. In vivo, evaluations of imaging and tissue morphology assessments suggested that disc height index, magnetic resonance imaging grade and histological score were significantly improved from the degenerative models when NAC-CDs was applied. In conclusion, the study developed a novel carbon dots nanozyme, which efficiently rescues IVDD from ROS induced NPCs senescence and provides a potential strategy in management of IVDD in clinic. This article is protected by copyright. All rights reserved.