Synthesis And Application Of Novel Fluorescent Polymer Nanoparticles Via Miniemulsion Polymerization Method

This work is mainly focused on preparation and application of novel fluorescentpolymeric nanoparticles, which is based on fluorescence resonance energy transfer(FRET) principle. The results show that these polymeric nanoparticles have someexcellent fluorescent properties, can be used in biological imaging or chemical sensor.The main contents and the results of this work are as following:1. At first, a red hydrophobic fluorescent dye,10-(diethylamino)-5-oxo-5H-benz-o-[a]phenoxazin-2-yl-methacrylate (NRME) was covalently incorporated intopolymeric nanoparticle via a facile one-step miniemulsion polymerization. Spectralcharacteristics demonstrated that the red fluorescent dye has been successfullyembedded into the nanoparticle. By optimizing the addition of surfactant, the smallersize of polymer nanoparticle can be obtained. Moreover, fluorescent polymericnanoparticle with different fluorescence intensity can be obtained by control thecontent of the NRME dye. This work provides important reference data for using thered fluorescent dye NRME in synthesis and properties of the FRET-based multi-colorfluorescent polymer nanoparticle.2. Secondly, we synthesized fluorescent polymeric nanoparticles incorporatedwith three polymerizable organic dyes via a one-pot miniemulsion. By altering thedoping ratio of three tandem dyes, the nanoparticles display abundant multiplefluorescence such as blue, cyan, green, orange, pink, red etc., together withdistinguishable emission signatures under a single wavelength excitation, which werearising from the effective fluorescence resonance energy transfer (FRET) between thethree energy-matched dyes. Meanwhile, a large Stokes shift (up to250nm) can begenerated by taking place multiple FRET cascade mechanism between donor andacceptor fluorophores in nanoparticles, which also suggests broad applications inbiological labeling and imaging. Moreover, these nanoparticles are uniform in size,highly bright, excellently photostable, and shown prominent long-term stability.Overall, the novel multicolor fluorescent polymeric nanoparticles augur well for theirpotential applications in multiplexed bioanalysis and emitting displays. 3. Finally, we have developed a FRET-based chemosensing system withpolymeric nanoparticle as the scaffold for Cu2+detection in water. The core-shellnanoparticle sensor was prepared by a facile one-pot miniemulsion polymerization, inwhich the fluorescent dye (4-methamino-9-allyl-1,8-naphthalimide, MANI) wascovalently incorporated into particle core and the Cu2+ligand (Vinylbenzylcyclam,VBC), chemically linked onto the surface. The cyclam-functionalized fluorescentpolymeric nanoparticles exhibit a high affinity for Cu2+ions in aqueous media. Uponthe addition of Cu2+, the fluorescent emission of MANI dye in nanoparticles can bequenched on the basis of intraparticle fluorescence resonance energy transfer (FRET)from the dye in the hydrophobic PMMA core to the Cu2+/cyclam complexes on thenanoparticle surface, and the nanoparticle sensor can selectively detect the Cu2+inwater with the detection limit of500nM. This strategy could provide a new approachfor detecting of Cu2+in environmental and biological applications and could beapplied to construct other FRET-based sensors for other metal ion detection.