Microbial Toxicity of a Type of Carbon Dots to Escherichia coli.
Carbon dots (Cdots), as a class of novel photoluminescence nanoprobes, has attracted tremendous interest for its broad application in recent years. Thus, the toxicity and behavior of Cdots in biological systems become important fundamental problems that require significant attention. In this study, Cdots with diameters of 5 nm are produced using mixed-acid treatment. The Cdots exhibit strong yellow fluorescence under UV irradiation and shifted emission peaks as the excitation wavelength is changed. Gram-negative bacteria Escherichia coli (E. coli) are applied as testing model to study the biological effect of Cdots on the cell growth by microcalorimetric, spectroscopic, and microscopic investigation. The introducing of Cdots caused a gradual increase of the maximum heat power (P peak) and the total heat produced (Q total) at low concentrations (0.0-5.00 mg/L). The metabolism rate constant (k) and half inhibitory concentration (IC50) were calculated from the microcalorimetric data. The results indicated that Cdots had a concentration-dependent effect on the growth of E. coli. For confirmation, the growth curves and colony-forming units at different concentration of Cdots were studied. The morphology of E. coli in the absence and presence of Cdots was determined by scanning electron microscopy (SEM). The results of these studies were in agreement well with the analysis explored from microcalorimetry.
School of Civil and Environmental Engineering, and National International Cooperation Based on Environment and Energy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, China.
Wenjuan
W
Liu
School of Civil and Environmental Engineering, and National International Cooperation Based on Environment and Energy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, China. yaojun@ustb.edu.cn.|Key Laboratory of Biogeology and Environmental Geology of Chinese Ministry of Education, and Sino-Hungarian Joint Laboratory of Environmental Science and Health, China University of Geoscience, Wuhan, 430074, China. yaojun@ustb.edu.cn.
Jun
J
Yao
School of Civil and Environmental Engineering, and National International Cooperation Based on Environment and Energy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, China.
Jingnan
J
Jin
School of Civil and Environmental Engineering, and National International Cooperation Based on Environment and Energy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, China.
Jiaheng
J
Ma
Department of Botany, Faculty of Science, University of Ruhuna, Matara, Sri Lanka. masakorala12@yahoo.com.
Kanaji
K
Masakorala
D004926:Escherichia coli / Q000187:drug effects*; D045663:Quantum Dots / Q000633:toxicity*; D018675:Toxicity Tests