Fluorescence “turn on” probe for bromide ion using nanoconjugates of glutathione-capped CdTe@ZnS quantum dots with nickel tetraamino-phthalocyanine: Characterization and size-dependent properties

• Glutathione capped CdTe@ZnS quantum dots have been conjugated to nickel tetraamino-phthalocyanine.
• The fluorescence of quantum dots was “turned off” on conjugation.
• The fluorescence was turned on by bromide ions.
• The conjugate was used as a sensor for bromide ion detection.

In this paper, three differently sized glutathione (GSH)-capped CdTe@ZnS quantum dots (QDs) have been successfully conjugated to nickel tetraamino-phthalocyanine (NiTAPc) to form different QDs-NiTAPc nanocomplexes. Several techniques such as TEM, FT-IR, time-resolved fluorescence measurement and electronic spectroscopy were employed to characterize the nanocomplex. Bromide ion was chosen as a model anion to test the efficacy of the nanoprobe. The fluorescence of the nanoconjugate was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion. Experimental results showed that the quantum size effect of nanocrystal QD determined the overall sensitivity and selectivity of the nanoprobe and followed the order QD563-NiTAPc > QD605-NiTAPc > QD621-NiTAPc. The mechanism of reaction is proposed.

Differently sized glutathione capped CdTe@ZnS quantum dots have been successfully conjugated to nickel tetraamino-phthalocyanine to form nanoconjugates whose fluorescence was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion.Figure optionsDownload as PowerPoint slide