Construction And Application Of Stimuli-responsive Fluorescent Polymer Materials Based On RAFT Polymerization

Stimuli-responsive fluorescent materials are a class of materials that can change their autofluorescence properties according to external environmental stimuli.Traditional organic small molecule stimuli-responsive fluorescent materials usually have problems such as poor water solubility,low stability,and poor biocompatibility.In order to overcome the shortcomings of small molecule stimuli-responsive fluorescent materials,in recent years,stimuli-responsive fluorescent polymer materials constructed by living polymerization methods such as reversible addition-fragmentation chain transfer polymerization（RAFT）have received extensive attention from the scientific community owing to their advantages of flexible structural design and functional modification,etc.Based on this,two types of stimuli-responsive fluorescent polymer materials were designed and synthesized in this paper to realize the response to hydrazine hydrate（N₂H₄）,hydrogen sulfide（H₂S）/biothiol,and further applied to latent fingerprints（LFP）fluorescence imaging,autofluorescence reporter release of sulfur dioxide（SO₂）.The main contents and results are as follows:1.The amphiphilic random copolymer(P(PEG₃₀-co-FHA₆))was obtained by RAFT polymerization in which 4-formyl-3-hydroxyphenyl acrylate（FHA）was used as the hydrophobic group and poly（ethylene glycol）methacrylate（PEGMA）as the hydrophilic group.Fluorescent polymer micelles（PMs）with N₂H₄ crosslinking-induced fluorescence emission were constructed by method of self-assembly.N₂H₄ acted both as a specific fluorescence activator to obtain yellow-green fluorescence and as a cross-linking agent to improve micelle stability.Notably,PMs with N₂H₄ crosslinking-induced fluorescence emission possess aggregation-induced fluorescence（AIE）and excited-state intramolecular proton transfer（ESIPT）properties,effectively overcoming the aggregation-induced fluorescence quenching（ACQ）defects of traditional organic dyes.PMs have the advantages of good water dispersibility（100%aqueous solution）,high selectivity,large Stokes shift（about 150 nm）,low detection limit（23 n M）,good photostability and long-term stability.In addition,PMs were successfully applied to high-contrast fluorescence imaging of 1-3 level latent fingerprint details on different material surfaces.2.The amphiphilic random copolymer Gal-P(PEG₁₅-co-（FITC-2DC）₃)was designed and synthesized by combining RAFT polymerization and click chemistry with2,4-dinitrobenzenesulfonate-fluorescence（FITC-2DC）as the hydrophobic group and polyethylene glycol（PEG）and galactose（Gal）molecules as hydrophilic groups.The H₂S/biothiol-activatable self-fluorescence reporter releasing SO₂ polymer nanomicelles was then obtained by co-precipitation using above copolymer.In the presence of H₂S/biothiol,the2,4-dinitrobenzenesulfonate bond in the polymer nanomicelles was cleaved,resulting in obvious green fluorescence and release of SO₂ to realize the feature of self-fluorescence reporter releasing SO₂.In addition,the polymer nanomicelles have the advantages of good water dispersibility and good biocompatibility,and are expected to be able to specifically target liver cancer cells and release SO₂ by self-fluorescence reporter,providing strong support for the research on SO₂ gas therapy of tumor cells.