title: Crossover between Anti- and Pro-oxidant Activities of Graphene Quantum Dots in the Absence or Presence of Light.
abstract: Graphene quantum dots (GQDs), zero-dimensional carbon materials displaying excellent luminescence properties, show great promise for medical applications such as imaging, drug delivery, biosensors, and novel therapeutics. A deeper understanding of how the properties of GQDs interact with biological systems is essential for these applications. Our work demonstrates that GQDs can efficiently scavenge a number of free radicals and thereby protect cells against oxidative damage. However, upon exposure to blue light, GQDs exhibit significant phototoxicity through increasing intracellular reactive oxygen species (ROS) levels and reducing cell viability, attributable to the generation of free radicals under light excitation. We confirm that light-induced formation of ROS originates from the electron-hole pair and, more importantly, reveal that singlet oxygen is generated by photoexcited GQDs via both energy-transfer and electron-transfer pathways. Moreover, upon light excitation, GQDs accelerate the oxidation of non-enzymic anti-oxidants and promote lipid peroxidation, contributing to the phototoxicity of GQDs. Our results reveal that GQDs can display both anti- and pro-oxidant activities, depending upon light exposure, which will be useful in guiding the safe application and development of potential anticancer/antibacterial applications for GQDs.
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.|Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
authors: Yu
authors: Y
authors: Chong
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.|Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
authors: Cuicui
authors: C
authors: Ge
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.
authors: Ge
authors: G
authors: Fang
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.
authors: Xin
authors: X
authors: Tian
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.
authors: Xiaochuan
authors: X
authors: Ma
authors: Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
authors: Tao
authors: T
authors: Wen
authors: Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
authors: Wayne G
authors: WG
authors: Wamer
authors: Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China and Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100190, China.
authors: Chunying
authors: C
authors: Chen
authors: School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.|Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China and Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100190, China.
authors: Zhifang
authors: Z
authors: Chai
authors: Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
authors: Jun-Jie
authors: JJ
authors: Yin
keywords: anti-oxidants; free radicals; graphene quantum dots; lipid peroxidation; phototoxicity