Preparation And Application Of Novel Fluorescent Conjugated Polymer Nanoparticles

In recent years,conjugated polymers have attracted great interest for wide applications in photoelectric devices,chemical or biological sensing,fluorescentimaging,and photodynamic therapy owing to their excellent photoelectric properties.Among them,fluorescent conjugated polymer nanopartilces have certain unique features such as good photostability,good biocompatibility,and ease of surface functionalization,exhibiting promising prospects in biological imaging and sensing.In order to cope with the rapid development of conjugated polymer nanoparticles in biological fields,this project was based on the features of ease of functionalization for fluorescent conjugated polymer nanopartilces,focusing on the preparation of functionalized fluorescent conjugated polymer nanoparticles and their applications,and the details are listed as follows:1.The sialic acid-imprinted fluorescent conjugated polymer nanoparticels were designed and prepared,which exhibited recognition specifity toward cancer cells with surface sialic acid overexpression.A fluorescent conjugated polymer modified with phenylboronic acid as its side chains was synthesized.The phenylboronic acid group can reversibly bind with cis-diol-containing compounds,which can be utilized to fabricate the sialic acid involved conjugated polymer nanoparticles via reprecipitation method.Then,the covalent bond between phenylboronic acid and sialic acid was destroyed by adjusting pH value,and sialic acid molecules were removed by dialysis process,leaving sialic acid-imprintedNPs.The sialic acid-imprinted NPs exhibited recognition specifity toward SA molecules.The cell imaging assay indicated that the sialic acid-imprinted nanoparticles could selectively bind with sialic acid overexpressed in DU 145 cancer cells and did not enter HeLa cells at all.The sialic acid-imprinted NPs as a fluorescent probe would have good potential for application in the early diagnosis of cancers.2.The super photoswitch molecule with eight dithienylethene units was designed and prepared.The super photoswitch molecule has the ability to control the fluorescence emission of conjugated polymer nanoparticles between "ON" and"OFF" state via alternate irradiations of UV and visible light.A super photoswitch molecule POSS-DTE8 was designed and synthesized.uwhich was composed of a polyhedral oligomeric silsesquioxanes(POSS)core and eight dithienylethene units as the photoswitching quencher.Moreover,a classic photoswitch molecule DTE-Ph2 composed of one dithienylethene unit was also syhthesized as the control sample.The super photoswitch molecule exhibited quick response speed,excellent stability and good fatigue resistance.The super photoswitch molecule together with three conjugated polymers showing different emissive colors were used to prepare composite nanoparticles via reprecipitation method.With the same concentration of dithienylethene units between POSS-DTE8 and DTE-Ph2,POSS-DTE8 had the better capacity to photochemically control the fluorescence emission of conjugated polymer nanoparticles,as well as films.3.The novel fluorescent conjugated polymer intergrating energy donor and acceptor into the backbone was designed and prepared.The fluorescence resonance energy transfer efficiency was regulated by adjusting the aggregation degree of nanoparticles,to achieve the goal of adjusting the fluorescence colors of nanoparticles.A conjugated polymer which integrated blue-,green-and red-emitting components into the backbone with an appropriate molar ratio was synthesized.After being transferred from solution to nanoparticles,its fluorescence color turns from blue to pink.After incorporation of an amphiphilic polymer as matrix,white-emissive polymer nanoparticles were obtained as a result of optimized energy transfer degree among the three components.The prepared white-emissive polymer nanoparticles showed good biocompatibility and well performance on cell imaging which could be observed by three channels.