Polymerizable aggregation-induced emission dye for preparation of cross-linkable fluorescent nanoprobes with ultra-low critical micelle concentrations

In recent years, aggregation-induced emission (AIE) dyes based fluorescent organic nanoparticles (FONs) have achieved significant progress in various biomedical applications. In this work, we developed a covalent strategy to prepare biocompatible AIE-active dyes based cross-linked copolymers (MPC-POSS-PhE) via controllable reversible addition fragmentation chain transfer (RAFT) polymerization using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC), polymerizable AIE dye (named as PhE) and 8-vinyl polyoctahedral silsesquioxanes (POSS) as monomers. Due to the existence of hydrophilic MPC and hydrophobic PhE, the resultant copolymers will self-assemble into core-shell nanoparticles in aqueous solution with ultra-low critical micelle concentration (CMC). This could effectively overcome the drawbacks of non-crosslinked micelles and show more attractive properties and better performance for biomedical applications. Furthermore, the characterization results and biological assays demonstrated that the final MPC-POSS-PhE FONs show stable aqueous stability, uniform size and morphology, high water dispersity, desirable optical properties and low cytotoxicity. These remarkable properties make the resultant AIE-active nanoprobes great potential for biomedical applications.