Tb doped carbon dots as a platform for fluorescence ratiometric and colorimetric sensor for deferasirox.

Tb doped carbon dots (Tb-CDs) were synthesized by a simple hydrothermal method and the existence of Tb in the obtained CDs was confirmed by the several characterization methods. Tb-CDs were exploited to design a ratiometric fluorescence sensor for deferasirox (DFX) assay. CDs and Tb acted as reference and sensing probs in the sensor. In the presence of DFX, the fluorescence intensity of CDs remained unchanged, while Tb emission increased. The fluorescence ratio of Tb to CDs was proportional to the DFX concentration at the range of 0.1 to 2.5 µM. Additionally, the fluorescence color altered from blue (CDs emission) to green (Tb emission) with increasing DFX concentration. We employed this color variation to establish a smartphone based sensor for the DFX detection. The linear range of established sensor was 0.5-15 µM. The detection limit (3S) for the ratiometric and smartphone based sensor was calculated to be 0.08 and 0.4 µM, respectively. Both sensors were applied to measure DFX in human serum samples with satisfactory results.