Fig. 4
a PLs intensity and peak position of NCDs in different pH values. b PL intensity ratios (F/F0) of NCDs, F0 is the PL intensity of the original NCDs, while F is that of NCDs treated with different metal ions (50 μM). c PL spectra of NCDs treated with the increasing titrations of Ag+ from 0 to 300 μM, λex = 400 nm. d Plot of fluorescent intensity of NCDs against Ag+ concentration in the range of 0 to 300 μM