Abstract
In this work, ammonium pyrrolidine dithiocarbamate (APDC) was used as a surface etchant to modify CdTe/CdS core-shell quantum dots (QDs). The APDC etchant combines with the cadmium ions (Cd2+) on the surface of the QDs, resulting in the formation of surface holes. The formation of these holes changes the QD surface structure, which leads to fluorescence quenching of the QDs. Newly added Cd2+ can selectively recognize and combine with these holes; thus, the fluorescence intensity of the QDs can be restored. The linear response of this turn-on fluorescent sensor was found to be 0–100 μg/L and 100–600 μg/L under the determined optimal conditions, and its limit of detection (LOD) for Cd2+ was 2.642 μg/L (23.5 nmol/L).
Highlights
Cadmium is a highly toxic heavy metal with a long biological half-life, accumulates in organisms, and is difficult to eliminate [1,2,3]
The need for cadmium detection has increased over the past few years, and the methods commonly used for cadmium detection are atomic absorption spectrometry (AAS) [10,11], atomic emission spectrometry (AES) [12,13], inductively coupled plasma mass spectrometry (ICPMS) [14,15], conductometric analysis (CA) [16,17], anodic stripping voltammetry (ASV) [18,19,20,21], immunoassays, and biosensors
This sensor is formed by using ammonium pyrrolidine dithiocarbamate (APDC) to etch the surface of cadmium telluride (CdTe)/CdS core-shell quantum dots (QDs), which leads to the formation of holes on the QD surface that cause fluorescence quenching
Summary
Cadmium is a highly toxic heavy metal with a long biological half-life, accumulates in organisms, and is difficult to eliminate [1,2,3]. A simple CdTe/CdS core-shell QD sensor that uses the turn-on mode was developed for portable and rapid detection of Cd2+ , and compared with the single-core QD structure, the core-shell structure leads to stronger fluorescence stability, higher fluorescence efficiency, and lower toxicity. This sensor is formed by using ammonium pyrrolidine dithiocarbamate (APDC) to etch the surface of CdTe/CdS core-shell QDs, which leads to the formation of holes on the QD surface that cause fluorescence quenching.
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