A ratiometric fluorescent nanoprobe for the specific and portable detection of tetracycline based on Eu/N, S-doped carbon dots.

The development of a sensitive sensing platform for monitoring tetracycline hydrochloride (TCH) is of particular significance for safeguarding human health and food safety. Herein, a ratiometric nanofluorescent probe called Eu/N, S-CDs was designed by the combination with N, S-doped carbon dots (CDs) and europium ions (Eu). TCH could lead to blue fluorescence (FL) emission at 464 nm quenched through static quenching, while could enhance red FL emission at 617 nm via the antenna effect. The proposed sensor had a wider linear detection range of 0.05-45 μM and a lower detection limit (LOD) of 5.92 nM for monitoring TCH. Moreover, the Eu/N, S-CDs-loaded test strips endowed a visual and convenient detection with a smartphone-assisted equipment based on TCH-induced FL color transition from blue to red. Importantly, satisfactory recoveries were achieved for actual sample analysis, indicating the great potential applications for food quality protection and public health safeguarding.