Carbon nanodots (CNDs): tuning structures and functions in oxidative radical interactions

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Zuowei Ji (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Jianjun Wei

Abstract: Carbon nanodots (CNDs), reported as polyatomic carbon domains surrounded by amorphous carbon frames, have drawn extensive attention due to their easy-to-synthesis, outstanding optoelectronic properties, and superior biocompatibility. Moreover, CNDs have shown good antioxidant capabilities by scavenging free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH•) and reactive oxygen species (ROS). While some studies suggest that the antioxidation activities associate to the proton donor role of surface-active groups like carboxyl groups (-COOH), it is unclear how the functional groups or composites on CNDs’ surfaces affect the antioxidation of CNDs. Meanwhile, limited assessments on the biological effects of CNDs, particularly the effect on oxidative stress in living cells, have restricted their further development. To address this issue, we propose to tune CNDs’ structures and examine the interactions between the oxidative radicals and the CNDs. In this work, we have 1) modified the surface functional groups of CNDs, specifically the -COOH and -NH2 groups, to investigate the interactions with DPPH• in chemistry, and 2) doped additional elements (e.g. nitrogen and/or sulfur) to change the composites/structures of CNDs and study their interactions with oxidative radicals in vitro. The results demonstrate that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH•. In addition, the nitrogen doped CNDs (N-CNDs) exhibited excellent biocompatibility and antioxidation capability in two cell lines, EA.hy926 (normal cells) and A549 (lung cancer cells). Whereas, relatively high doses treatment of the nitrogen sulfur doped CNDs (N,S-CNDs) cause in vitro cytotoxicity by stimulating more generation of intracellular ROS in the two cell lines. Further intracellular studies indicate that both the N-CNDs and N,S-CNDs mostly are localized at the mitochondria of the cells. These results suggest that the CNDs may regulate the electron transport chain in mitochondria for ROS generation, and the sulfur element and associated functional groups in the CNDs play a key role for the ROS generation. In summary, the findings in this dissertation work presents some advances in knowledge of structure-functions of CNDs for radical scavenging, intracellular process and oxidative stress effect in living cells, which may accelerate the practical development in the field of biomedicine. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]

Additional Information

Language: English
Date: 2020
Antioxidant, Biocompatibility, Bioimaging, Carbon nanodots, Prooxidant, Reactive oxygen species
Nanostructured materials

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