Highly Photoluminescent Nitrogen-Doped Carbon Nanodots and Their Protective Effects against Oxidative Stress on Cells.

Highly photoluminescent (PL) (quantum yield = 54%) nitrogen doped carbon nanodots (C-dots) have been prepared through one-step carbonizing citric acid and tris(hydroxymethyl)aminomethane and using oleic acid as solvent. The synthesized C-dots are monodisperse with narrow size distribution (average 1.7 nm). The PL properties of C-dots are pH dependent, and hence, using C-dots as sophisticated pH sensor to detect pH values between 7 and 9 can be expected. In addition, the PL intensity of C-dots remains stable under high ionic strength. The C-dots can protect cells from oxidative stress, which shows potential to expand the biological application of C-dots, especially in medical treatment. The protective mechanism is associated with intracellular reactive oxygen species elimination and the intracellular superoxide dismutase production.