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.