Ring-opening crosslinking PEGylation of an AIE epoxy monomer towards biocompatible fluorescent nanoparticles

Here we report the ring-opening crosslinking PEGylation of an AIE epoxy monomer and a 4-arm PEG-amine to prepare a new cross-linked fluorescent polymer (PEG-EP3). When PEG-EP3 was dispersed in aqueous solution, the AIE components formed the hydrophobic cores and the PEG parts covered the surfaces, resulting in fluorescent polymeric nanoparticles (FPNs) with good dispersibility. PEG-EP3 and the resulting FPNs were characterized by gel permeation chromatography, ¹H NMR spectroscopy, FT-IR spectroscopy, X-ray photoelectron spectroscopy, dynamic light scattering, transmission electron microscopy, UV-Visible absorption and fluorescence spectra. The results confirmed the successful synthesis of PEG-EP3, which showed high water dispersibility with a size distribution of 249 ± 1 nm, intense yellow-green fluorescence in aqueous solution with a fluorescence quantum yield of 35%, and a low critical micelle concentration (CMC) of 0.039 mg mL^-1. The cell uptake behaviour and cell imaging of the PEG-EP3 FPNs proved their high biocompatibility for biomedical applications. Owing to their excellent biocompatibility by the introduction of PEG as the main component, good colloidal stability with low CMC, and high fluorescence stability, the strategy in this work would provide a new approach to prepare novel biocompatible and robust cross-linked FPNs for biomedical applications.