Ultrasensitive fluorescent probe for copper ion based on cadmium selenide/cadmium sulfide quantum dots capped with dimercaprol

A new ultrasensitive copper ion fluorescent probe based on cadmium selenide/cadmium sulfide quantum dots capped with dimercaprol is described. Dimercaprol was bonded to the quantum dots through a surface ligand exchange to form dimercaprol-capped quantum dots whose fluorescence could be quenched by the coordination of dimercaprol on quantum dots' surface with copper ion. The fluorescent probe based on dimercaprol-capped quantum dots showed a very good linear response range to copper ion from 0.1 to 50 mu gL(-1) with the detection limit of 0.087 mu gL(-1). The proposed method exhibited excellent sensitivity and selectivity due to the specific and strong affinity of dimercaprol with copper ion and the unique photoluminescence properties of quantum dots. The possible quenching mechanism was discussed and the probe was successfully applied to the determination of ultratrace copper in real samples.