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

Abstract

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 QDs 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 QDs 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 μM (r² = 0.9919) with a detection limit of 0.34 μM. Furthermore, the proposed sensor was applied to detect Cu²⁺ in drinking water samples with %recovery values of 102-114% and %RSD less than 6%.

Keywords: Chemical sensors; Chiral nanoparticles; Circular dichroism spectroscopy; Nanoparticles; Optical nanomaterials.