Synthesis of l-glutathione-capped-ZnSe quantum dots for the sensitive and selective determination of copper ion in aqueous solutions

l-Glutathione capped (GSH) ZnSe quantum dots (QDs) have been synthesized as a fluorescence ions probes for ultrasensitive Cu (II) detection. These QDs surface decoration with glutathione shells can be directly applied without previous treatment. The fluorescence quenching of the GSH-capped-ZnSe QDs depends on the concentration, pH values and reaction time of the Cu2+ solution. Based on the effective electron transfer from GSH to Cu2+ and the surface ligand stripping occurs onto the surface of ZnSe QDs, it results in the reduction of Cu2+ to Cu+ and increment of surface defection on the surface of the QDs. Under the optimum conditions, the detection limit of Cu2+ is 2 × 10−10 mol L−1. Meanwhile, the effect of foreign ions displays a low interference response in the detecting of Cu2+ ions. Moreover, based on the invariable absorption peak position and curtate luminescence lifetime of ZnSe QDs, the quenching process has also been confirmed to be a dynamic quenching procedure. With regard to the practical feasibility test of the fluorescent probe, a relative lower standard deviation (RSD) (≤3%) and a high recovery rate demonstrate that the proposed simple method is sensitive, accurate and reliable.