Ultrasensitive Cu2+ sensing by near-infrared-emitting CdSeTe alloyed quantum dots

The near-infrared (NIR)-emitting CdSeTe alloyed quantum dots (AQdots) that capped with l-cysteine were applied for ultrasensitive Cu2+ sensing. The sensing approach was based on the fluorescence of the AQdots selectively quenched in the presence of Cu2+. Experimental results showed a low interference response towards other metal ions. The possible quenching mechanism was discussed on the basis of the binding between l-cysteine and the metal ions. In addition, biomolecules have low effect on the fluorescence due to the minimized interferences in NIR region. The response of the NIR optical sensor was linearly proportional to the concentration of Cu2+ ranging from 2 × 10−8 to 2 × 10−6 mol L−1. Furthermore, it has been successfully applied to the detection of Cu2+ in vegetable samples.