Green Luminescent CdTe Quantum Dot Based Fluorescence Nano-Sensor for Sensitive Detection of Arsenic (III)

Arsenic (As³⁺) is a hazardous and ubiquitous element; hence the quantitative detection of arsenic in various kinds of environmental sample is an important issue. Herein, we reported L-cysteine capped CdTe Quantum dot based optical sensor for the fluorometric detection of arsenic (III) in real water sample. The method is based on the fluorescence quenching of QDs with the addition of arsenic solution that caused the reduction in fluorescence intensity due to strong interaction between As³⁺ and L-cysteine to form As(Cys)₃. The calibration curve was linear over 2.0 nM-0.5 μM arsenic with limit of detection (LOD) of 2.0 nM, correlation coefficient (r²) of 0.9698, and relative standard deviation (RSD %) of 5.2%. The Stern-Volmer constant for the quenching of CdTe QDs with As³⁺ at optimized condition was evaluated to be 1.17 × 10⁸ L mol^-1 s^-1. The feasibility of the sensor has been analyzed by checking the inference of common metal ions available in the water such as K⁺, Na⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Al³⁺, Co²⁺, Cr²⁺, Fe³⁺ and its higher oxidation state As⁵⁺. Graphical Abstract Schematic representation of As³⁺ detection by L-Cysteine capped CdTe QDs.