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Core–shell structured CdTe/CdS@SiO 2 @CdTe@SiO 2 composite fluorescent spheres: Synthesis and application for Cd 2 + detection
Author(s) -
Liu Fang,
Li Shujia,
Hu Ruoxin,
Shao Na
Publication year - 2017
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.3242
Subject(s) - cadmium telluride photovoltaics , fluorescence , quantum dot , materials science , nanoparticle , luminescence , nanotechnology , analytical chemistry (journal) , optoelectronics , chemistry , optics , physics , chromatography
Core–shell structured quantum dot (QD)–silica fluorescent nanoparticles have attracted a great deal of attention due to the excellent optical properties of QDs and the stability of silica. In this study, core–shell structured CdTe/CdS@SiO 2 @CdTe@SiO 2 fluorescent nanospheres were synthesized based on the Stöber method using multistep silica encapsulation. The second silica layer on the CdTe QDs maintained the optical stability of nanospheres and decreased adverse influences on the probe during subsequent processing. Red‐emissive CdTe/CdS QDs (630 nm) were used as a built‐in reference signal and green‐emissive CdTe QDs (550 nm) were used as a responding probe. The fluorescence of CdTe QDs was greatly quenched by added S 2 − , owing to a S 2 − ‐induced change in the CdTe QDs surface state in the shell. Upon addition of Cd 2 + to the S 2 − ‐quenched CdTe/CdS@SiO 2 @CdTe@SiO 2 system, the responding signal at 550 nm was dramatically restored, whereas the emission at 630 nm remained almost unchanged; this response could be used as a ratiometric ‘off–on’ fluorescent probe for the detection of Cd 2 + . The sensing mechanism was suggested to be: the newly formed CdS‐like cluster with a higher band gap facilitated exciton/hole recombination and effectively enhanced the fluorescence of the CdTe QDs. The proposed probe shows a highly sensitive and selective response to Cd 2 + and has potential application in the detection of Cd 2 + in environmental or biological samples.