Carbon nanodots (CNDs) are 0D quasi-spherical nanoparticles that are less than 10 nm in size. CNDs that possess surface functional groups such as hydroxyl, amino, and carboxyl groups have been demonstrated to scavenge free radicals efficiently and effectively, resulting in them being beneficial for cosmetic and cosmeceutical applications. In this study, we successfully prepared novel CNDs, namely black VC, using vitamin C (VC) as a promising precursor. Black VC was prepared by a facile one-step method based on short-time microwave irradiation. The properties of black VC were characterized by transmission electron microscopy (TEM) analysis, X-ray diffraction (XRD), high-resolution X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and UV–vis spectrophotometry. Radical scavenging, cell viability, and anti-pollution activity assays were also conducted to demonstrate the functionalities of black VC. The developed black VC exhibited lower cytotoxicity and better antioxidant, metal chelating ability, and anti-pollution activities than its precursor. These results provide a new approach for developing advanced antioxidants for innovative cosmetic formulations using a simple microwave treatment method. However, black VC retained some problems of its precursor in the form of low stability, which is likely to be a challenge for its cosmeceutical application.

    Abstract
        Graphical abstract
    1 Introduction
    2 Materials and methods
        2.1 Materials
        2.2 Preparation of black VC
        2.3 Instrumentation and characterization of black VC
        2.4 DPPH radical scavenging assay
        2.5 OH radical scavenging assay
        2.6 Long-term stability analysis
        2.7 Cell culture
        2.8 Cell viability
        2.9 Anti-pollution activity assays
    3 Results and discussion
        3.1 Preparation and characterization of black VC
        3.2 Antioxidant activity of black VC
        3.3 Cytotoxicity of black VC
        3.4 Anti-pollution activity
        3.5 Long-term stability of black VC
    4 Conclusion
    Acknowledgements 
    References

• Vinh Van Tran(Laser and Thermal Engineering Laboratory, Department of Mechanical Engineering, Gachon University)
• Ju‐Young Moon(Department of Beauty Design Management, Hansung University)
• Young‑Chul Lee(Department of BioNano Technology, Gachon University)