Vitamin C derived carbon dots: inhibiting amyloid aggregation and scavenging reactive oxygen species†

Abstract

The pathogenesis of Alzheimer's disease is very complex, so its multifunctional treatment is of great significance, in which the synergistic therapy of the amyloid cascade hypothesis and oxidative stress hypothesis shows good results. In this study, bifunctional carbon dots (CACDs) that can inhibit amyloid aggregation and relieve oxidative stress were synthesized. Studies have shown that CACDs have a good antioxidant effect. When the concentration of CACDs is 100 μg mL⁻¹, the elimination efficiency of DPPH (2,2-diphenyl-1-picrylhydrazyl) reaches 65.57%, and the scavenging efficiency of ˙O₂⁻ and ˙OH reaches 79.6% and 73.9%, respectively. Moreover, CACDs possess outstanding scavenging abilities against the ROS in cells, thus resulting in the mitigation of cellular oxidative damage. Meanwhile, CACDs can also bind to lysozyme proteins through hydrophobic interactions to further interfere with the amyloid self-assembly process. According to thioflavin T (ThT) analysis, the inhibition efficiency of CACDs on amyloid proteins gradually increases with increasing concentration. Circular dichroism spectroscopy (CD) further indicates that the CACDs can inhibit the transition of the protein structure to the β-sheet structure. CACDs and Aβ₄₂ also have strong binding ability. CACDs have excellent biocompatibility and can alleviate the cytotoxicity caused by Aβ oligomers. The results demonstrate that CACDs have promising applications in multifunctional materials and important applications in multi-target therapy of Alzheimer's disease.