Peroxynitrite and nitric oxide fluorescence sensing by ethylenediamine doped carbon dots

The selective fluorescence sensing of nitric oxide (NO) and peroxynitrite anion (ONOO-) in the presence of the principal reactive oxygen and nitrogen species (ROS/RNS) was achieved by fluorescence quenching through the pH variation of microwave synthesized fluorescent carbon dots (CDs) prepared from citric acid (CA) and ethylenediamine (EDA). The highest NO and ONOO- sensitivity, with the lowest sensitivity to the principal ROS/RNS, was demonstrated respectively at pH 4 and 10. The optimum synthesis and sensing conditions of CDs were obtained by multivariate full factorial experimental design methodologies: for NO, at pH 4, 2.5g of CA and 1000 mu L of EDA diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700W; for ONOO-, at pH 7, 10-0.25 g of CA and 500 mu L of EDA diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700W. In these optimized conditions the synthesized CDs have a quantum yield about 40%. The quantification of NO at pH 4 and of ONOO- at pH 7 and 10 were done in standard and in fortified serum solutions. Also the quantification of NO and of ONOO- in standard solutions was performed in the presence respectively of ONOO- and NO. (C) 2015 Elsevier B.V. All rights reserved.