| المستخلص: |
The Susuki-Miyaura cross coupling polymerisation approach to formation of emissive conjugated polymer nanoparticles was presented and the flexibility of the method for preparation of particles with different emission colours was demonstrated. The as-prepared nanoparticle dispersions were clear (not turbid) and the particle hydrodynamic diameters were small, < 60 nm. Zeta potentials of the particles were strongly negative, consistent with the presence of negative surface charge on the particles, possibly due to defect formation. Spectroscopic data revealed that the particle absorption/emission was characteristic of the parent polymer. Values of photoluminescence quantum yields and lifetimes of particle dispersions were determined. The estimated radiative decay rate constants were similar to those of fluorescence dyes (ca. 108 s-1) used in flow cytometry or fluorescence imaging, and higher than those of quantum dots. Photo stability studies carried out for aqueous nanoparticle dispersions indicated that some particle types exhibited mild photo brightening under continuous illumination with stability generally observed for all particles. These observations demonstrated that the particles were more stable than conventional molecular fluorophores. Single nanoparticle imaging studies confirmed that the particles were bright with good signal-to-background characteristics being observed for all particle types. Measurements of single particle photo bleaching trajectories indicated that the majority of particles exhibited largely continuous photo bleaching behavior consistent with the multichromophoric character expected for particles composed of aggregated conjugated polymer chains with comparatively large total numbers of emissive chromophores. A few particles exhibited fluorescence intermittency or emission blinking behavior during photo bleaching which was ascribed to reversible, time-varying fluctuations in the fraction of chromophores in the emitting ('on") state present within particles composed of relatively small total numbers of emissive chromophores. Single particle death numbers of ca.
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