Facile synthesis of yellow fluorescent carbon dots for highly sensitive sensing of cobalt ions and biological imaging

Abstract

Long-wavelength light emission has been garnering extensive attention in terms of strong tissue penetration ability and weak light scattering effects. Herein, nitrogen-doped carbon dots (N-CDs) with bright yellow fluorescence emission at 555 nm are facilely synthesized through hydrothermal-assisted heating of o-phenylenediamine and urea. The as-prepared N-CDs exhibit low cytotoxicity, high biocompatibility, photobleaching resistance, and multiple functional groups. Based on the formation of a stable non-fluorescent ground-state complex, the fluorescence intensity of N-CDs is linearly quenched by Co²⁺ in the range of 0.1–30 μM and the detection limit is as low as 52 nM. The method has been successfully applied for precise analysis of actual samples. Furthermore, the N-CDs satisfactorily serve as a staining probe for the in vivo bioimaging of zebrafish.