Luminescence Enhancement based Sensing of L-Cysteine by Doped Quantum Dots

The interaction of a presynthesized orange emitting Mn²⁺ -doped ZnS quantum dots (QDs) with L-Cysteine (L-Cys) led to enhance emission intensity (at 596 nm) and quantum yield (QY). Importantly, the Mn²⁺ -doped ZnS QDs exhibited high sensitivity towards L-Cys, with a limit of detection of 0.4±0.02 μM (in the linear range of 3.3-13.3 μM) and high selectivity in presence of interfering amino acids and metal ions. The association constant of L-Cys was determined to be 0.36×10⁵  M^-1 . The amplified passivation of the surface of Mn²⁺ -doped ZnS QDs following the incorporation and binding of L-Cys is accounted for the enhancement in their luminescence features. Moreover, the luminescence enhancement-based detection will bring newer dimension towards sensing application.