High Quantum Yield Boron and Nitrogen Codoped Carbon Quantum Dots with Red/Purple Emissions for Ratiometric Fluorescent IO4– Sensing and Cell Imaging

A facile and cost-effective hydrothermal method was developed for the preparation of boron and nitrogen codoped carbon quantum dots (B,N-CQDs) from 3-carboxyphenylboronic acid and o-phenylenediamine. The synthesized B,N-CQDs exhibit excellent properties such as excellent water solubility, strong fluorescence, good dispersion, and desirable stability. The average particle size of B,N-CQDs is 2.82 nm, and the absolute fluorescence quantum yield is 86.58%. The excitation wavelength of B,N-CQDs is 300 nm. Emission bands of B,N-CQDs appeared at 356 and 700 nm. Periodate (IO4–) quenches B,N-CQDs emissions through chelation reaction. The ratio of F356/F700 has a good linear relationship with the concentration of IO4– in the range of 0.01–40 μmol/L with the detection limit of 0.003 μmol/L. This method has the advantages of a low detection limit, high sensitivity, wide linear range, good selectivity, simplicity, and rapidness. It can be used as a ratiometric fluorescent probe for the detection of IO4–, and it was successfully applied in the analysis of IO4– in water. The cytotoxicity and biocompatibility of B,N-CQDs were evaluated and successfully applied in cell imaging.