Gadolinium-doped red carbon dots exert inhibitory effects on catalase activity: An integrated investigation of computational modeling and cellular responses.

Catalase, a vital antioxidant enzyme, plays a pivotal role in maintaining cellular redox homeostasis. Dysregulation of its activity in tumor cells has emerged as a promising target for cancer therapy. Given the ultra-small size and unique physicochemical properties of carbon dots, which enable effective binding to catalase, this study aimed to investigate the inhibitory mechanism of gadolinium-doped red carbon dots (Gd-CDs) on catalase activity and their resultant biological effects. To achieve this, an integrated approach combining multispectral technology, molecular docking, dynamic simulation, and cellular experiments was employed. Computational modeling revealed that Gd-CDs form stable complexes with catalase through van der Waals forces, hydrogen bonds, and hydrophobic interactions, with a binding free energy (ΔG) of -5.25 kcal·mol-1. Enzyme activity assays further demonstrated that the inhibition of Gd-CDs followed a mixed-type competitive mechanism. Cellular experiments showed distinct cytotoxic effects: Gd-CDs exhibited a significantly lower survival rate in HeLa tumor cells (58.95 %) compared to normal GES-1 cells (82.80 %). In vitro analyses revealed that Gd-CDs reduced catalase activity by 53.74 % and induced abnormal cellular morphology, leading to cytotoxicity and cellular damage. Collectively, this study elucidates the binding mechanism between Gd-CDs and catalase, offering novel insights into nanomaterial-mediated enzyme regulation. Moreover, it highlights the potential of modulating catalase levels via Gd-CDs as a promising strategy for tumor treatment, opening new avenues in cancer therapeutics.