Highly selective circular dichroism sensor based on D-penicillamine/cysteamine-cadmium sulfide quantum dots for copper (II) ion detection

A highly selective circular dichroism sensor based on cysteamine-capped cadmium sulfide quantum dots (Cys-CdS QDs) was successfully developed for the determination of Cu2+, Basically, the Cys-CdS QDs are not active in circular dichroism spectroscopy. However, the circular dichroism probe (DPA@Cys-CdS QDs) can be simply generated in situ by mixing achiral Cys-CdS QPs with D-penicillamine. The detection principle was based on measuring the circular dichroism signal change upon the addition of Cu2+. The strong CD signal of the DPA@Cys-CdS QPs dramatically decreased in the presence of Cu2+, while other cations did not result in any spectral changes. In addition, the degree of the CD signal decrease was linearly proportional to the concentration of Cu2+ in the range of 0.50-2.25 mu M (r(2) = 0.9919) with a detection limit of 0.34 mu M. Furthermore, the proposed sensor was applied to detect Cu2+ in drinking water samples with %recovery values of 102-114% and %RSD less than 6%. (C) 2018 Elsevier B.V. All rights reserved.