The Construction Of AIE-Active Fluorescent Polymeric Nanoparticles Base On Post-Modification Polymerization Method

The construction of fluorescent polymeric nanoparticles is an important field in biomedical research.Despite small molecular organic dyes and inorganic fluorescent nanomaterials exhibit superior optical properties,poor photostability and essentially non-degradable properties limit its development in biomedical field.In contrast,fluorescent polymeric nanoparticles have the advantages of designability,biocompatibility and biodegradability,which are beneficial to biomedical imaging and treatment.However,conventional organic dyes suffer from Aggregation-caused quenching(ACQ)effect,it is difficult to construct fluorescent polymeric nanoparticles with intense fluorescence.Fortunately,Benzhong Tang' group discovered the phenomenon of aggregation-induced emission(AIE)in 2001,thus it is possible to construct high-emissive fluorescent polymeric nanoparticles.AIE based fluorescent polymeric nanoparticles are usually prepared by synthesizing AIE dye firstly,and then copolymerizing with hydrophilic monomers or self-assembling with amphiphilic polymers.Compared with this conventional scheme,we proposed a novel post-modification polymerization method to synthesize AIE active fluorescent polymeric nanoparticles.The main contents of each chapter are as follows:In second chapter,a novel proposal based on post-modified amphiphilic polymers with AIE property was presented for constructing non-invasive bioprobe.Firstly,aniline-functionalized copolymers were successfully prepared by reversible additionfragmentation chain transfer(RAFT)polymerization.Subsequently,salicylaldehyde(SA)as the post-modification reactant could be directly reacted with the amino group of the copolymer.Such copolymers were prone to self-assemble into stabilized nanoparticles with size about 100-200 nm in aqueous solution owing to their amphiphilic property.The fluorescence intensity of the assembled particles was significantly enhanced and could be used in cell imaging.In third chapter,we developed AIE-active fluorescent polymeric nanoparticles through a combination of RAFT polymerization and post-polymerization modification strategies.The SA containing zwitterionic copolymers were fabricated via RAFT polymerization and further modified by benzophenone hydrazone via Schiff base reaction.The obtained copolymers tend to form nanoparticles in aqueous solution as a result of their amphiphilic structure.Results demonstrate that the nanoparticles exhibit desirable morphology and size,good dispersibility,high brightness,remarkable photostability and large Stokes shifts.Through cell cytotoxicity test and cell uptake behavior,the nanoparticles were demonstrated their potential for cell imaging applications.In fourth chapter,we developed AIE-active amphiphilic copolymers through a cross-linked strategy that hydrazine hydrate was served as the cross-linking agent for conjugating SA-functionalized amphiphilic copolymers.The obtained amphiphilic copolymers tend to self-assemble into stable nanoparticles with diameters ranging from 100 to 200 nm.A series of analysis methods suggested the nanoparticles possess good water dispersibility,intensive yellow fluorescence,large stokes shift,remarkable photostability,low critical micelle concentration(CMC)value and excellent biocompatibility.More importantly,the cell uptake behavior of the nanoparticles demonstrated that they are capable of promising potential in biological imaging.