New Insights into the Cellular Toxicity of Carbon Quantum Dots to Escherichia coli

• Published in: Antioxidants Vol. 11; no. 12; p. 2475
• Main Authors: Qiang, Shirong, Zhang, Li, Li, Zhengbin, Liang, Jianjun, Li, Ping, Song, Jiayu, Guo, Kunling, Wang, Zihuan, Fan, Qiaohui
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.12.2022; MDPI
• Subjects: Biocompatibility; biologic toxicity; Carbon; carbon quantum dots; Cell culture; Cell death; Cell surface; Cell walls; Confocal microscopy; Cytotoxicity; DNA damage; E coli; Edema; Graphene; L-Lactate dehydrogenase; Lactic acid; Lipid peroxidation; membrane permeability; Nanoparticles; Osmotic pressure; Oxidative stress; Particle size; Permeability; Quantum dots; Reactive oxygen species; Scanning electron microscopy; Toxicity; Transmission electron microscopy; Zeta potential; osmotic pressure; biologic toxicity; membrane permeability; E. coli; carbon quantum dots
• ISSN: 2076-3921; 2076-3921
• DOI: 10.3390/antiox11122475

In this study, the cytotoxicity and toxic mechanism of carbon quantum dots (CQDs) to were evaluated in vitro. The synthetic CQDs were extremely small in size (~2.08 nm) and displayed strong fluorescence. The results demonstrated that CQDs showed good biocompatibility with within a short culture time. However, when the exposure time exceeded 24 h, the toxicity of CQDs became apparent, and the contents of reactive oxygen species, lactate dehydrogenase, and the crystal violet absorption rate increased significantly. To further explore the cytotoxic mechanism, approaches including confocal laser scanning microscopy, scanning electron microscopy, and biological transmission electron microscopy combined with zeta potential tests, osmotic pressure measurement, and comet assays were performed. On the one hand, the CQDs altered the surface charges of cells and induced lipid peroxidation by adhesion on the surface of , leading to an increase in the permeability of the cell wall. On the other hand, when the concentration of CQDs reached 200 µg/mL, the osmotic pressure of the extracellular environment was significantly reduced. These are the main factors that lead to cell edema and death. Finally, the comet assays confirmed that CQDs could induce DNA damage, which could inhibit the proliferation of .