Luminescent Behavior Regulation,Surface Modification,and Applications Of AIE Polymeric Nanoparticles

Fluorescent nanoparticles(NPs)have the advantages of easy surface functionalization,small particle size and good emission performance.It is necessary to design the NPs with tunable luminescence behavior to addressing the requirement in luminescent devices,bio-imaging and bio-sensors applications.By introducing aggregation-induced luminescence(AIE)molecules into fluorescent nanoparticles,the fluorescence intensity of fluorescent nanoparticles increased significantly due to restricted intramolecular motion.However,the the regulation of AIE NPs’s luminescence behavior was usually ahieved by the combination of multiple fluorescent molecules.This method remained big challenges such as unstable fluorescence spectrum,poor reproducibility and complicated preparation routes.Therefore,by selcting AIE luminogens with AIE effect and twisted intramolecular charge transfer(TICT)effect,a novel technique of modulating the emission behavior of AIE-PNPs based on the polymer matrix was provided.In this paper,(E)-2-(3-cyano-5,5-dimethyl-4-(4-(1,2,2-triphenylvinyl)styryl)furan-2(5H)-ylidene)malononitrile(TPE-TCF)with AIE effect and TICT effect was synthesized,and TPE-TCF displays polarity-dependent emission behaviors.In chapter 2,a novel technique of regulating the emission behavior of AIE-PNPs was provided.The tunable luminescence behavior’s polymers/TPE-TCF AIE-PNPs were prepared by miniemulsion copolymerization of methyl methacrylate(MMA)and comonomers with various polarities.The increased or reduced polarity of the polymer matrix could lead to red-shifted or blue-shifted emission of polymer/TPE-TCF AIE-PNPs,respectively.The polarity-dependent emission behavior of polymer/TPE-TCF AIE-PNPs was generally validated in the AIE-PNPs with various polymer matrices.More importantly,the white-light-emitting polymer/TPE-TCF AIE-PNPs(WLE AIE-PNPs)could be generally synthesized via miniemulsion copolymerization of MMA with stearyl methacrylate,lauryl methacrylate,n-hexyl methacrylate,and cyclohexyl methacrylate at an appropriate monomer composition.By simply coating a layer of prepared WLE AIE-PNPs onto UV LED chips,the UV light could be successfully converted to white light,clearly demonstrating their great application potential in electronic and photonic devices.In chapter 3,research groups provided a method for simple surface modification of AIE-PNPs,and amino-functionalized AIE-PNPs with orange-red emitting(AIE-NH2-PMANPs)were efficiently synthesized through a miniemulsion copolymerization of MMA and an amino-containing functional comonomer(AEMH).AIE-NH2-PMANPs displayed a well-defined spherical morphology with a sub-100 nm particle size,and narrow particle size distribution.The surface amino density of AIE-NH2-PMANPs could be conveniently tuned by the AEMH content.AIE-NH2-PMANPs has an amino density of 0.48 mmol·g-1.The surface of AIE-NH2-PMANPs were further modified with maleimide groups and HIV-1 Tat peptides through a sequential carbodiimde reaction and a thiol-maleimide click reaction.The peptide-modified AIE-PNPs displayed good photostability and colloidal stability under continuous light irradiation or under various pH values,as well as good storage stability in aqueous media.The cell uptake efficiency of AIE-PNPs was significantly improved by the surface modification of HIV-1 Tat peptides,achieving good cell fluorescence imaging quality under a relatively low AIE-PNP concentration.In the miniemulsion polymerization system,AIE-PNPs with tunable luminescence behaviors were prepared by the miniemulsion copolymerization between methyl methacrylate and comonomers with different polarities,and the most profound application was the successful preparation of WLE AIE-PNPs.Meanwhile,the characteristics of comonomers could change the surface chemical properties of AIE-PNPs,providing convenient conditions for further surface chemical modification.The proposed method in this manuscript has high versatility and the prominent luminescence behavior suitably position AIE-PNPs for the applications in luminescent device field,fluorescent cell imaging field.