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Talanta. 2014 Sep;127:68-74. doi: 10.1016/j.talanta.2014.01.046. Epub 2014 Feb 16.

Presence of photoluminescent carbon dots in Nescafe® original instant coffee: applications to bioimaging.

Author information

1
School of Biological & Food Engineering, Dalian Polytechnic University, Dalian 116034, China; Division of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
2
Division of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
3
School of Biological & Food Engineering, Dalian Polytechnic University, Dalian 116034, China. Electronic address: wangjh@dlpu.edu.cn.
4
Division of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. Electronic address: mqtan@dicp.ac.cn.

Abstract

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.

KEYWORDS:

Bioimaging; Carbon dots; Nescafe(®) original instant coffee; Photoluminescent

PMID:
24913858
DOI:
10.1016/j.talanta.2014.01.046
[Indexed for MEDLINE]

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