Preparation of PEGylated and biodegradable fluorescent organic nanoparticles with aggregation-induced emission characteristics through direct ring-opening polymerization

Fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) characteristics have emerged as ideal probes in fluorescent imaging for visualization of complex biological processes by taking advantages of excellent optical properties, designability and biocompatibility. Significant progresses in the syntheses of AIE-active FONs open up new possibilities in biological applications, whereas, only limited attention was focused on the fabrication of biodegradable FONs through the ring-opening polymerization (ROP) of AIE-active N-carboxyanhydrides (NCA) monomers. In this work, L-Cysteine (Cys) is functionalized with an AIE dye in the side chain, and then transformed into polymerizable NCA monomer with AIE feature. In the next step, amino-terminated poly(ethylene glycol) (PEG) was directly used to initiate the ROP of AIE-active NCA. The prepared amphiphilic copolymers contain hydrophilic PEG and hydrophobic AIE dye have a tendency to self-assemble into core-shell nanostructure. Results confirmed mPEG(5000)-CysPhe FONs owned high water dispersibility and excellent optical properties. Besides, biological evaluation results demonstrated that these AIE-active FONs possess good biocompatibility and fluorescent imaging performance. More importantly, the strategy also be extend for the preparation other polypeptides based fluorescent probes with desired structure and functions. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.