Fluorescence emission spectra of Cys-CdS QDs (—) upon the addition of 0.05 mM Fe3+ (red line) 0.5 lM (dashed line) and 2 lM (dotted line) PPi in the presence (A) and
absence (B) of Fe3+ in 0.1 mM Tris–HCl buffer pH 7.5. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)