Improvement of fluorescence properties by surface modification of CdS-ZnS quantum dots by thiol compounds and its application as a sensitive fluorescence probe for copper ion detection.

The capped CdS-ZnS quantum dots (QDs) were synthesized with various thiol capping agents of glycolic acid (TGA), mercaptosuccinic acid (MSA), and L-cysteine (LCY) and used as fluorescence probe for determination of Cu (II) ions. The method of two-level three-factor full-factorial experiment design was used to achieve the best optical fluorescence emission. Results revealed that Cu (II) ions can effectively quench the emission of QDs, and the fluorescence intensity is linearly decreased with increasing Cu (II) ion concentration.