Development of dual function polyamine-functionalized carbon dots derived from one step green synthesis for quantitation of Cu and S ions in complicated matrices with high selectivity.

The study of biologically important Cu and S ions has drawn great attention in the recent years since an abnormal level of these ions is an indication for health impairment. Therefore, a reliable strategy for effective fluorescence determination of Cu and S ions was developed. Simply, the method based on economical plant-dependent thermolysis procedure for efficient green synthesis of water dispersible luminescent polyamine-based carbon dots (PA@C-dots) utilizes Vitis vinifera juice as precursor with a high quantum yield (32.1%) and good photo-stability. The fluorescent PA@C-dots were characterized by different spectroscopical, physical, and structural techniques. Furthermore, the synthesized PA@C-dots can be used as an efficient dual functional fluorescent probe for the sensitive and selective estimation of Cu and S ions. The incorporation of Cu ions and their adsorption on the surface of PA@C-dot skeleton leads to the respectable fluorescence quenching of C-dots (turn-off mode). The Cu-PA@C-dot was found to be sensitive to S ions. The addition of S recovers the fluorescence (turn-on mode) of Cu-PA@C-dots, thanks to its capacity for withdrawing Cu from the shell of PA@C-dots. Fluorescence quenching in the range of 0.07-60 μM Cu was obtained with LOD and LOQ of 0.02 and 0.066 μM, respectively. Sulfide detection provides linearity in the range of 0.8 to 95 μM with LOD and LOQ of 0.24 and 0.79 μM, respectively. The optimal excitation and emission wavelengths for all experiments are 435 nm and 498 nm, respectively. Experiment results elucidate that the proposed method is suitable for Cuand S ion detection in environmental water samples. Graphical abstract Green synthesis of polyamine-functionalized nanoprobe by thermolysis method from plant source as bifunctional sensing platform for determination of Cu and S in environmental water samples.