Fluorescent sensing system for the determination of L-Cys based on SQDs/MnO2 NS with a wide linear range

A fluorescent sensing method is presented for the determination of L -Cysteine ( L -Cys) based on sulfur quantum dots (SQDs)/MnO 2 nanosheets (MnO 2 NS) nano system. SQDs was prepared from hydrothermal reaction from sublimed sulfur with β-Cyclodextrin as the surface ligand. SQDs have intense fluorescence which will be quenched in the presence of MnO 2 NS. After the addition of L -Cys, the redox reaction of MnO 2 NS and L -Cys results in the recovery of SQDs fluorescence. Under optimal conditions, the sensing system could achieve a sensitive detection of L -Cys with a wide linearity in the range of 8.0 μM-1.0 mM and a detection of limit as 2.44 μM (3σ/k). This sensing method also shows an excellent specificity and anti-inference, which has a great potential application for the real sample detection. The SQDs-MnO 2 NS served as a promising sensing system for the identification of L -Cys.