Controllable synthesis of green and blue fluorescent carbon nanodots for pH and Cu2+ sensing in living cells

We report a controllable strategy for fabrication of green and blue fluorescent carbon nanodots (CDs), and demonstrate their applications for pH and Cu2+ sensing in living cells. Green and blue fluorescent CDs have been synthesized by hydrothermal method and pyrolysis of leeks, respectively, providing an easy way for the production of CDs without the request of tedious synthetic methodology or the use of toxic/expensive solvents and starting materials. Green fluorescent CDs (G-CDs) exhibit high tolerance to pH values and external cations. Blue fluorescent CDs (B-CDs) can be applied to pH and Cu2+ sensing. The linear range of Cu2+ detection is 0.01-10.00 mu M and the detection limit is 0.05 mu M. For pH detection, there is a good linearity in the pH range of 3.5-10.0. The linear and rapid response of B-CDs to Cu2+ and pH is valuable for Cu2+ and pH sensing in living cells. Confocal fluorescent imaging of human cervical carcinoma cells indicates that B-CDs could visualize Cu2+ and pH fluctuations in living cells with negligible autofluorescence. (C) 2015 Elsevier B.V. All rights reserved.