Green fluorescent organic nanoparticles based on carbon dots and self-polymerized dopamine for cell imaging

Fluorescent organic nanoparticles (FONs) based on polydopamine (PDA) have recently emerged as a novel fluorescent probe due to its facile synthesis procedure, good water solubility, and excellent biocompatibility. However, previously reported PDA-FONs show low monodispersity and efficiency, which largely limit their application. In this study, we report a new type of FONs that has been prepared using carbon dots (CDs) as seeds and assembled via the self-polymerization of dopamine molecules. The prepared FONs showed high efficiency and monodispersity; moreover, via controlling the time of the polymerization reaction, different FONs could be obtained, which demonstrated similar structures but with tunable emission properties, and the emission gradually evolved from blue to green with the increasing reaction time. The mechanism of the prepared FONs was confirmed to be via the Forster resonance energy transfer (FRET) effect occuring between CDs and polymerized dopamine, leading to high efficiency and tunable emission. The FONs were also explored for cell imaging and cytotoxicity experiments, and they showed excellent biocompatibility and good prospects in biotechnological applications.