An Unconventional Polymerization Route to Hydrophilic Fluorescent Organic Nanoparticles for Multicolor Cellular Bioimaging

We demonstrated an unconventional polymerization route to synthesize hydrophilic fluorescent organic nanoparticles (FONs) for multicolor cellular bioimaging in this contribution. The route benefits from our unexpected discovery of a rapid polymerization reaction between 1,6-hexanediol dipropiolate and 2,4,6-triazide-1,3,5-triazine under the catalysis of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA). Interestingly, the 2,4,6-triazide-1,3,5-triazine and PMDETA system can also induce rapid free radical polymerization at room temperature. The as-prepared FONs exhibited promising water solubility and stability with an average diameter of 20 nm. The excitation wavelength-dependent fluorescent properties endow the FONs with blue, yellow, and red fluorescent emission under UV, blue, and green excitation, respectively. The cytotoxicity of FONs was investigated by using a Cell Counting Kit (CCK-8) assay, which indicated good biocompatiblity. More importantly, the cell uptake experiment verified the FONs were excellent fluorescent nanoprobes for multicolor cellular bioimaging. Therefore, this unconventional route provides a novel fabrication strategy of highly hydrophilic FONs for biomedical applications.