We report the simple one-step hydrothermal green synthesis of carbon dots (CDs) without any chemical reagents using mangosteen pulp (CDs1), peel (CDs2), and leaf (CDs3) extract as a green carbon source. In the aqueous medium, these CDs had a size of 8–15 nm with an energy gap of about 4 eV. The CDs emitted a bright green color under ultraviolet (UV) irritation with an average fluorescence quantum yield of the CDs of 1.6%. Moreover, the CDs contained various functional groups, such as C = C, C–C, C–O–C, C–O, C = O, C–H, and O–H, which were beneficial for enhancing their fluorescence property. Furthermore, the CDs were applied in the stain fluorescent imaging of myosatellite chicken stem cells and Vero cells. The CDs2 and CDs3 induced a strong fluorescence emission intensity of the strain cells, whereas CDs1 acted as the highest potential enhancer in cell proliferation as confirmed by its cellular viability which was the around four times that of the control. Therefore, the CDs were highly biocompatible and acted as enhancers in cell proliferation in myosatellite chicken stem cells and Vero cells. Thus, simple, cost-effective, scalable, and green synthetic approach-based CDs show promise for the development of selective organelle labeling and optical sensing probes.

The potential of carbon dots produced from mangosteen through green synthesis for induced-cell proliferation and fluorescence bioimaging
    Abstract
        Graphical abstract
    1 Introduction
    2 Experimental section
        2.1 Materials and instrumentations
        2.2 Synthesis of CDs
        2.3 Fluorescence quantum yield measurements
        2.4 Cytotoxicity test
        2.5 Fluorescence imaging experiments
    3 Results and discussion
        3.1 Structural characterization of the CDs
        3.2 Energy band gap
        3.3 The surface functional groups
        3.4 Optical properties
        3.5 Cytotoxicity and cell imaging
    4 Conclusions
    Acknowledgements 
    References

• Tanachporn Lukprang(Department of Physics, Faculty of Science and Technology, Thammasat University, Pathumthani 12120, Thailand)
• Pakorn Preechaburana(Department of Physics, Faculty of Science and Technology, Thammasat University, Pathumthani 12120, Thailand, Thammasat University Research Unit in Innovation of Optical Devices and Nanomaterials for Chemical and Biological Sensing, Thammasat University, Pathumthani 12120, Thailand)
• Supaluck Amloy(Department of Physics, Faculty of Science and Technology, Thammasat University, Pathumthani 12120, Thailand, Thammasat University Research Unit in Innovation of Optical Devices and Nanomaterials for Chemical and Biological Sensing, Thammasat University, Pathumthani 12120, Thailand) Corresponding author
• Monthon Lertworapreecha(Microbial Technology for Agriculture, Food and Environment Research Center, Faculty of Science, Thaksin University, Phatthalung 93210, Thailand)