CNDs Synthesis

CNDs were synthesized by a microwave-assisted method using citric acid (0.96 g, 99%, ACROS Organics), 1.0 mL ethylenediamine (99%, Alfa Aesar) and 1.0 mL deionized H₂O. This solution was mixed in a glass vial and heated in a microwave synthesizer (CEM Corp 908005) at 300 W for 18 minutes. The resulting solution was then dialyzed against deionized water (1000 MWCO, Fisher Scientific) for 24 hours. Then, the solution was dried using freeze-dryer (FreeZone 6, Labconco), which gave the final solid product. Following lyophilization CNDs samples were then diluted to a 2 mg/mL in deionized water, and the fluorescence properties were measured in a quartz cuvette.