One-pot synthesis and biological imaging application of an amphiphilic fluorescent copolymer via a combination of RAFT polymerization and Schiff base reaction

Abstract

In recent years, fluorescent organic nanoparticles (FONs) based on aggregation induced emission (AIE) dyes have received increasing attention for their potential in biology and biochemistry. In this contribution, a novel one-pot method for the fabrication of AIE-based FONs was developed via a combination of reversible addition–fragmentation chain-transfer (RAFT) polymerization and Schiff base reaction for the first time. During this procedure, an aldehyde functionalized hydrophobic tetraphenylethene AIE dye (named TPEA) reacted with the amine group of an amino-ended methacrylamide monomer by the Schiff base reaction, and the vinyl group in the monomer synchronously participated in RAFT polymerization together with a PEGMA monomer to form a new fluorescent copolymer. The as-prepared copolymer tended to self-assemble into FONs with the hydrophobic AIE core covered by a hydrophilic PEG shell, and the molar fractions of TPEA and PEG in the copolymer were about 20% and 80%, respectively, with 29 200 g mol⁻¹ (M_n) and a narrow polydispersity index (PDI) (∼1.30). The prepared amphiphilic copolymer nanoparticles (named TPEA-PEG) exhibited good fluorescence features and excellent dispersibility in aqueous solution. More importantly, these FONs presented a spherical morphology, uniform size (∼100 nm), and excellent biocompatibility, making them promising candidates for bioimaging applications.