A green microwave method using glycine and urea as precursors was developed to synthesize carbon dots (CDs). The CDs can be used as an effective fluorescence probe with high selectivity and sensitivity for the detection of morin based on the fluorescence quenching of CDs.

In this work, a novel fluorescence nanosensor for selective and sensitive determination of amaranth was constructed using carbon dots (C-dots). Water soluble C-dots with strong fluorescence were obtained by a simple microwave-assisted method using urea and glycine as raw materials. It was found that amaranth can efficiently and sensitively quench the C-dots fluorescence by the inner filter effect (IFE) and non-radiative energy transfer (NRET) mechanisms. The fluorescence quenching efficiency (F₀/F) was strongly correlated with the concentration of amaranth in the 0.2–30 μM range. The detection limit (LOD) is 0.021 μM. There was no significant change in the fluorescence intensity of C-dots when other potentially interfering substances were present in the system. Our C-dots-based nanosensor was successfully utilized for the analysis of amaranth in drinks and showed rapid, sensitive and accurate responses. It indicates that the novel C-dots-based nanosensor has great potential in amaranth detection for real-life applications.