Thioglycolic acid capped CdSe/ZnS quantum dot as fluorescent sensor for the detection of water-soluble hazardous heavy metal ions

In the present work, we have developed a rapid, cost-effective aqueous phase route to synthesize water-soluble Thioglycolic acid (TGA) capped CdSe/ZnS (CdSe/ZnS + TGA) QD sensor. Synthesized QD sensor has been successfully validated its candidature for the efficient detection of hazardous heavy metal ions ( X n + ) specifically chromium (Cr 3+ ) and copper (Cu 2+ ) in aqueous medium. In the presence of X n + metal ions, ‘‘Turn-Off’’ fluorescence response is observed due to the complex formation ( X n + : CdSe/ZnS + TGA). A strong 1:1 complexation ( X n + : CdSe/ZnS + TGA) between QD sensor and X n + metal ion is confirmed by the output of Benesi–Hildebrand relation and Job’s plot. As per our knowledge our proposed CdSe/ZnS + TGA QD sensor has established its efficient sensing capability for metal ions with lower detection of limit (LOD) up to concentration ~ 10 –7 M for the first time which is lower than permissible limit as per WHO data. The practical application of this system for determining metal ions in real samples has also been successfully demonstrated. Graphical Abstract