A ratiometric fluorometric and colorimetric probe for the β-thalassemia drug deferiprone based on the use of gold nanoclusters and carbon dots.

A turn-on fluorometric probe is described for the β-thalassemia drug deferiprone (DFP). The probe is making use of carbon dots (C-dots) and gold nanoclusters (AuNCs) which, under 340-nm excitation, display dual emission with peaks at 445 and 592 nm. The orange fluorescence of AuNCs is quenched after the addition of Fe(III), but recovered on addition of DFP. The blue fluorescence of the C-dots, in contrast, remains unchanged. The Fe(III)-DFP complex undergoes intermolecular electron transfer under UV excitation and displays only weak peaks in the UV region. The ratio of the two fluorescences is measured which makes the probe intrinsically self-calibrated. Colorimetry is best performed at a wavelength of 280 nm. The ratio of fluorescences increases linearly in the 0.1-80 μM DFP concentration range, and the detection limit is 0.1 μM. The respective figures for colorimetry are 2.5-120 μM and 0.3 μM. The probe is highly selective for DFP. Thus, it possesses a large potential for detection of DFP in serum. Graphical abstract The orange fluorescence of gold nanoclusters (AuNCs) is quenched by Fe3+ ions but recovered on addition of deferiprone (DFP), while the change of blue fluorescence in carbon dots (C-dots) is minimal. Moreover, the Fe(III)-DFP complex undergoes intermolecular electron transfer under ultraviolet (UV) irradiation, and absorption spectra can be observed in the presence of Fe(III)-DFP detected by UV scanning. Thus, a ratiometric fluorometric and colorimetric assay is developed for DFP.