Microwave-assisted synthesis of water-soluble Eu3+ hybrid carbon dots with enhanced fluorescence for the sensing of Hg2+ ions and imaging of fungal cells

In this work, a fluorescent nanosensor based on Eu3+ hybrid carbon dots (Eu3+-CDs) was fabricated by single-step microwave heating using ethylenediaminetetraacetic acid (EDTA), L-cysteine and europium(III) nitrate as reagents. The as-synthesized Eu3+ hybrid CDs exhibited a characteristic fluorescence emission peak at 427 nm upon excitation at a wavelength of 343 nm. Upon the addition of Hg2+ ions, the emission peak of the Eu3+ hybrid CDs was quenched and a linear relationship was observed between the fluorescence quenching intensity and the concentration of Hg2+ ions in the range of 5.0-250 mu M with a detection limit of 2.2 mu M. The developed nanosensor not only enables selective and sensitive detection of Hg2+ ions but also offers excellent applications in the confocal imaging of fungal cells (Fomitopsis sp.), which holds great promise in biomedical applications.