A ratiometric fluorescent nanoprobe based on quenched carbon dots-rhodamine B for selective detection of l-cysteine

The level of l-Cysteine (Cys) is an indicator for many diseases of human, thus the selective and sensitive detection of abnormal level of Cys is critically important for human health. In this paper, quenched-carbon dots- Rhodamine B (QCR) system has been developed for the selective and sensitive detection of Cys, where Hg2+-quenched carbon dots (CDs) serve as the reporting unit and the Rhodamine B as the reference unit. The detection limit for the Cys is 52.10 nM, which are much lower than the normal concentration in human urine. Moreover, the sensor shows excellent selectivity for Cys over other amino acids and common cellular ions and environmentally relevant anions.