A dual-emission polymer carbon nanoparticles for ratiometric and visual detection of pH value and bilirubin.

[Display omitted] • The dual emission polymer carbon nanoparticles PDA-OPD were synthesized. • The PDA-OPD exhibited dual emission peaks at 460 nm and 540 nm upon single excitation wavelength. • The PDA-OPD can be used for detection of pH value in the range from 3.0 to 7.4. • The PDA-OPD can be used for detection of bilibrubin in the alkaline environment. Herein, we prepared a novel fluorescent polymer carbon nanoparticles by polymerizing dopamine (DA) and o-phenylenediamine (OPD) through oxidation of hydrogen peroxide. In a neutral environment, the synthesized fluorescent polymer carbon nanoparticles (PDA-OPD) exhibited two emission peaks at 460 nm and 540 nm with 400 nm excitation wavelength. In an acidic environment, the fluorescence emission peaks of PDA-OPD at 540 nm showed an obvious fluorescence quenching, and there existed a good linear relationship between the fluorescence ratio F 540 /F 460 and environment pH value. In an alkaline environment, the fluorescence emission peak at 460 nm showed obvious fluorescence quenching after the addition of bilirubin, while a novel fluorescence emission peak at 560 nm emerged gradually. The PDA-OPD could be also used to detect bilirubin in the range of 0–400 μmol·L−1. [ABSTRACT FROM AUTHOR]