Journal
TALANTA
Volume 127, Issue -, Pages 68-74Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.talanta.2014.01.046
Keywords
Carbon dots; Nescafe (R) original instant coffee; Photoluminescent; Bioimaging
Categories
Funding
- National Nature Science Foundation of China [91227126]
- National Special Fund for Key Scientific Instrument and Equipment Development [2013YQ17046307]
- Nature Science Foundation of Liaoning Province, China [2013020177]
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The presence of the carbon dots (C-dots) in food is a hotly debated topic and our knowledge about the presence and the use of carbon dots (C-dots) in food is still in its infancy. We report the finding of the presence of photoluminescent (PL) C-dots in commercial Nescafe instant coffee. TEM analysis reveals that the extracted C-dots have an average size of 4.4 nm. They were well-dispersed in water and strongly photoluminescent under the excitation of ultra-violet light with a quantum yield (QY) about 5.5%, which were also found to possess clear upconversion PL properties. X-ray photoelectron spectroscopy characterization demonstrates that the C-dots contain C, O and N three elements with the relative contents ca. 30.1, 62.2 and 7.8%. The X-ray diffraction (XRD) analysis indicates that the C-dots are amorphous. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The C-dots show a pH independent behavior by varying the pH value from 2 to 11. The cytotoxicity study revealed that the C-dots did not cause any toxicity to cells at a concentration as high as 20 mg/mL. The C-dots have been directly applied in cells and fish imaging, which suggested that the C-dots present in commercial coffee may have more potential biological applications. (C) 2014 Published by Elsevier B.V.
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