PSS functionalized and stabilized carbon nanodots for specific sensing of iron in biological medium.

Carbon Quantum Dots (CQDs) are already emerged as an excellent sensing element for its exceptional behavior in fluorescence, biocompatibility, and water dispersibility. However, its poor stability, selectivity and reproducibility in complex medium still be a big problem for its practical application. To overcome this, in the work, we have developed a new type of carbon quantum dot-PSS fluorescent nanocomposites which has been used for specific Fe detection. The polystyrene sulfonate (PSS) polymer not only stabilize the QDs but also produces specific sites for Fe to make a co-ordinate complex via Fe-SO3. The detection limit is calculated as low as 1 ppm which is adequate for measuring Fe in blood or water samples. The mechanism of the quenching is very specific towards the Fe ion due to the presence of PSS which makes the sensor selective among other metal ions and possible interferences. The rapid process of sensing, simple instrumentation, and excellent performances in presence of 1 % BSA and serum samples indicates the possible application for diagnostic usage in near future.