A near-infrared-emitting CdTe/CdS core/shell quantum dots-based OFF-ON fluorescence sensor for highly selective and sensitive detection of Cd2+.

A near-infrared-emitting CdTe/CdS core/shell quantum dots (QDs)-based photoluminescence (PL) sensor was designed and applied for highly selective and sensitive detection of Cd(2+). This sensor was based on a PL "OFF-ON" mode. First, the addition of ammonium pyrrolidine dithiocarbamate (APDC) led to remarked PL quenching of QDs. Second, PL of APDC surface modified QDs (QDs-APDC) was gradually restored with the each increment of Cd(2+) concentration. Experimental results showed that PL of QDs-APDC was near proportional upon the addition of Cd(2+) in the range from 0.1 to 2 μM with a good correlation coefficient of 0.9989. The limit of detection of this proposed method was 6 nM. Interferential experiments confirmed that this sensor of Cd(2+) was highly selective over other metal ions. To further investigate perfect analysis performance, this sensor was favorably utilized to determine Cd(2+) in tap water, river water and liposome solutions.