Tuning The Amphiphilicity And Further Enhancing The Emission Of AIEgens Via Post-Polymerization Modification:Toward Application In Cell-Imaging

Aggregation Induced Emission(AIE)phenomenon is known for the lighting-up effect upon aggregation of the organic fluorescent molecules.The emergence of fluorescent materials with AIE effects has greatly promoted the development of luminescent materials.AIE molecules are widely used in cell imaging due to their excellent fluorescence properties and low noise background.Reversible Addition-Fragmentation Chain Transfer(RAFT)polymerization is a type of(actively)controlled radical polymerization.They can react at mild conditions and work on a wide range of monomers.Besides,by controlling the ratio of monomer and the chain transfer agent,we can prepare polymers with high molecular weight and narrow distribution.Recently,post-polymerization(PPM)method is used as vehicle for preparing functional polymers.PPM is a synthesis method that quantitatively converts inert groups in a polymer into other functional groups.In order to obtain good fluorescence properties,good hydrophilicity as well as low biological toxicity,amphiphilic fluorescent polymers were prepared by combination of RAFT polymerization and PPM method.Therefore,the aggregates formed by the assembly of PAF in aqueous solution have good fluorescence properties and can be successfully applied to cell imaging.Poly(acryloyl chloride pentafluorophenol)(denoted by PPFPA)with active reaction sites on the side chains was synthesized by RAFT polymerization.The fluorescent moleculeTPE-NH2 with AIE effect and the hydrophilic PEG-NH2 molecule were grafted to the side chain of PPFPA to prepare polymer amphiphilic fluorogen(denoted by PAF).By investigating its fluorescence properties,the results demonstrated that PAF not only have inherited the typical AIE effect,but also has priorities in terms of fluorescence emission than TPE-NH2 with the identical molar concentration of TPE unit.PAF molecules can assemble into fluorescent nanoparticles with sizes ranging from 100 to 300 nm in aqueous solution.The nanoparticles have good biocompatibility and can be successfully applied to labeling Hela cell.This work provides a practical strategy for preparing functional polymers.