Fish-scale-derived carbon dots as efficient fluorescent nanoprobes for detection of ferric ions

Herein, highly fluorescent carbon dots (CDs) with the incorporation of N and O functionalities were prepared through a facile and cost-effective hydrothermal reaction using fish scales of the crucian carp as the precursor. The as-prepared CDs exhibit strong fluorescent emissions at 430 nm with a relative quantum yield of 6.9%, low cytotoxicity, and robust fluorescence stability against photobleaching and good ionic strength. More significantly, the fluorescence of these CDs can be effectively and selectively quenched by Fe³⁺ ions, which enables the application of CDs as fluorescent Fe³⁺ nanoprobes with a linear range of 1-78 μmol L^-1 and a detection limit of 0.54 μmol L^-1. The proposed fluorescent CD nanoprobes can also be used for the assay of spiked Fe³⁺ in real water samples and human serums with high recoveries and low standard deviations. Hence, CDs can be potentially applied as safe and reliable fluorescent nanoprobes for environmental and clinical Fe³⁺ analyses.