Theranostics 2020; 10(17):7841-7856. doi:10.7150/thno.42291

Research Paper

Multifunctional N-P-doped carbon dots for regulation of apoptosis and autophagy in B16F10 melanoma cancer cells and in vitro imaging applications

Vivek K. Bajpai1, Imran Khan2,3, Shruti Shukla4, Sung-Min Kang5, Faisal Aziz3, Kumud Malika Tripathi6, Deepika Saini7, Hye-Jin Cho8, Nam Su Heo9, Sumit K. Sonkar7✉, Lei Chen10✉, Yun Suk Huh2✉, Young-Kyu Han1✉

1. Department of Energy and Materials Engineering, Dongguk University-Seoul, 30 Pildong-ro 1-gil, Seoul 04620, Republic of Korea.
2. Department of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, 100 Inha-ro, Nam-gu, Incheon 22212, Republic of Korea.
3. The Hormel Institute, University of Minnesota, Austin, MN, 55912, USA.
4. Department of Food Science and Technology, National Institute of Food Technology Entrepreneurship and Management (NIFTEM), Sonipat, Haryana 131028, India.
5. Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia, 30332, USA.
6. Department of Chemistry, Indian Institute of Petroleum and Energy, Visakhapatnam 531035, Andhra Pradesh, India.
7. Department of Chemistry, Malaviya National Institute of Technology, Jaipur, Jaipur 302017, India.
8. Reliability Assessment Center for Chemical Materials, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305-600, Republic of Korea.
9. Research Center for Materials Analysis, Korea Basic Science Institute (KBSI), Daejeon 34133, Republic of Korea.
10. College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.

This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.
Bajpai VK, Khan I, Shukla S, Kang SM, Aziz F, Tripathi KM, Saini D, Cho HJ, Su Heo N, Sonkar SK, Chen L, Suk Huh Y, Han YK. Multifunctional N-P-doped carbon dots for regulation of apoptosis and autophagy in B16F10 melanoma cancer cells and in vitro imaging applications. Theranostics 2020; 10(17):7841-7856. doi:10.7150/thno.42291. Available from

File import instruction


Rationale: The present study reports the multifunctional anticancer activity against B16F10 melanoma cancer cells and the bioimaging ability of fluorescent nitrogen-phosphorous-doped carbon dots (NPCDs).

Methods: The NPCDs were synthesized using a single-step, thermal treatment and were characterized by TEM, XPS, fluorescence and UV-Vis spectroscopy, and FTIR analysis. The anticancer efficacy of NPCDs was confirmed by using cell viability assay, morphological evaluation, fluorescent live-dead cell assay, mitochondrial potential assay, ROS production, RT-PCR, western-blot analysis, siRNA transfection, and cellular bioimaging ability.

Results: The NPCDs inhibited the proliferation of B16F10 melanoma cancer cells after 24 h of treatment and induced apoptosis, as confirmed by the presence of fragmented nuclei, reduced mitochondrial membrane potential, and elevated levels of reactive oxygen species. The NPCDs treatment further elevated the levels of pro-apoptotic factors and down-regulated the level of Bcl2 (B-cell lymphoma 2) that weakened the mitochondrial membrane, and activated proteases such as caspases. Treatment with NPCDs also resulted in dose-dependent cell cycle arrest, as indicated by reduced cyclin-dependent kinase (CDK)-2, -4, and -6 protein levels and an enhanced level of p21. More importantly, the NPCDs induced the activation of autophagy by upregulating the protein expression levels of LC3-II and ATG-5 (autophagy-related-5) and by downregulating p62 level, validated by knockdown of ATG-5. Additionally, owing to their excellent luminescence property, these NPCDs were also applicable in cellular bioimaging, as evidenced by the microscopic fluorescence imaging of B16F10 melanoma cells.

Conclusion: Based on these findings, we conclude that our newly synthesized NPCDs induced cell cycle arrest, autophagy, and apoptosis in B16F10 melanoma cells and presented good cellular bioimaging capability.

Keywords: N-P-doping, apoptosis, autophagy, bioimaging, cell cycle arrest, B16F10 melanoma cells