Design,Synthesis And Application Of Fluorescent Composites Based On Polymers

Fluorescent technology,which possesses advantages such as intuitional detection,facile operation,high sensitivity,and low cost,has been applied in biological sensing and chemical analysis.Nowadays,plenty of fluorescent dyes have been applied in biological sensing and imaging,as well as medical diagnose and treatment.However,traditional organic dyes generally show poor function,dispersity,brightness,biocompatibility and photostability,and these problems greatly impede the application of fluorescent technique.Therefore,in this paper,composites with different structures and functions were synthesized based on unique properties of noble metal nanoparticles,polymer,and organic dyes.The researclh details ae as follows.1.A fluorescent drug composite with core-shell structure was prepared by surface modification and crosslinking,and applied in intracellular drug release and fluorescent imaging.The disulfide bonds in the polymer shell could be broken by high glutathione(GSH)concentration in tumor cells cytosol,resulting in DOX release.The release processes extracellularly and intracellularly were demonstrated by change of fluorescent signal and morphology of composite,as well as observation by fluorescent microscope.Therefore,the composite could be applied in drug release and fluorescent imaging intracellularly.2.A fluorescent composite that could efficiently bind tumor cells with folate receptor overexpression was prepared by modifying Ag@PLL nanoparticle surface with folic acid and fluorescent dye FAM-SE.Taking advantage of metal-enhanced fluorescence(MEF)effect of Ag core,emission intensity of the dye was improved.Moreover,the intensity was adjusted by changing thickness of'PLL shell,and the composite could bind certain tumor cells through the interaction between folic acid and folate receptor.Fluorescent microscope observation after incubation of composite and tumor cells with different folate receptor expression demonstrated that the composite could be applied in selectively fluorescent imaging.So this study broadens the application of MEF effect in cellular imaging.3.A fluorescent composite that show integrin-binding ability was prepared by self-assembly,crosslinking and surface modification.Au nanoparticle was applied as core reduced by amino acid as reductant,and then PLL shell was fabricated through self-assembly and crosslinker.After that,fluorescent dye Cy3 and RGD,which is peptide with Gly-Arg-Asp sequence that could efficiently bind tumor cells with high integrin expression,were conjugated onto PLL shell surface.Since the SPR absorption of Au nanoparticle possessed obvious overlap with that of Cy3,emission intensity of Cy3 was enhanced because of excitation efficiency increase.The composite exhibited efficient binding to tumor cells with integrin overexpression due to RGD.Moreover,the composite show good biocompatibility because its synthesis was without using reductant and surfactant with high cytotoxicity.Therefore,the prepared composite could be applied as selectively fluorescent imaging material for tumor cells with integrin overexpression.4.A photosensitizer-loading composite with reactive oxygen species(ROS)improvement and controlled antibacterial effect was prepared by self-assembly,in situ reducing and surface modification.Positively charged polymer chitosan and negatively charged pol,mer poly(acrylic acid)were used to fabricate nanoparticles through self-assembly.Next,Au nanoparticles were reduced on the polymer nanoparticle surface,and photosensitizer Rose Bengal was linked to the surface.The composite show improved generation rate of ROS because of SPR effect of Au nanoparticles.Moreover,the composite could aggregate onto bacterial surface through the interaction between lectin ConA and chitosan,which greatly improved the antibacterial efficiency of ROS.So this study provides a new idea to design and develop controllable antibacterial materials.