Probing the sensitive and selective luminescent detection of peroxynitrite using thiol-capped CdTe and CdTe@ZnS quantum dots

CdTe and CdTe@ZnS quantum dots (QDs) capped with 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA), or glutathione (GSH) have been employed for the first time as luminescent probes for the sensitive and selective detection of peroxynitrite (ONOO-) in aqueous solution. The sensitivity of the proposed probe followed the order: MPA-(TGA)-CdTe@ZnS > GSH-(TGA)-CdTe@ZnS > MPA-CdTe QDs. The varying degree of quenching is elucidated based on the QD-thiolate bond of CdTe@ZnS being more sensitive to oxidation from ONOO- than CdTe. The selectivity of the probe in the presence of coexisting species followed the order: GSH-(TGA)-CdTe@ZnS > MPA-(TGA)-CdTe@ZnS > MPA-CdTe QDs. QDs capped with MPA showed less selectivity for ONOO- than GSH. The best limit of detection (LOD) of 12.6 nM was obtained for MPA-(TGA)-CdTe@ZnS QDs. Time-resolved fluorescence measurements indicated that the interaction between ONOO- and the QDs is static in nature. (c) 2012 Elsevier B.V. All rights reserved.