Synthesis and biological imaging of fluorescent polymeric nanoparticles with AIE feature via the combination of RAFT polymerization and post-polymerization modification

In recent years, florescent polymeric nanoparticles (FPNs) containing aggregation-induced emission (AIE) fluorogens have received great intention for their potential applications in biological imaging and theranostic nanomedicine . Herein, we have developed AIE-active FPNs through a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and post-polymerization modification strategies. The salicylaldehyde (SA) containing zwitterionic copolymers are fabricated via RAFT polymerization and further modified by benzophenone hydrazone (BPH) via Schiff base reaction. The obtained AIE-active amphiphilic copolymers BPH-poly(FHMA- co -MPC) can self-assemble in aqueous solution with the hydrophobic fluorogens aggregating together to form the core and the hydrophilic chains to form the protective shell. BPH-poly(FHMA- co -MPC) and the resulting FPNs are characterized by 1 H nuclear magnetic resonance spectroscopy , Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescence spectroscopy . Results demonstrate that BPH-poly(FHMA- co -MPC) are successfully synthesized and as-prepared BPH-poly(FHMA- co -MPC) FPNs exhibit desirable morphology and size, good dispersibility , high brightness, remarkable photostability and large Stokes shifts . More importantly, through cytotoxicity test and cell uptake behavior, these BPH-poly(FHMA- co -MPC) FPNs show low toxicity and excellent cell dyeing behavior. Taken together, we have developed a facile and effective method for the fabrication of AIE-active FPNs, which display great potential for biomedical applications .