Multicolor Conjugated Polymer Dots for Biological Fluorescence Imaging

Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
ACS Nano (Impact Factor: 12.88). 12/2008; 2(11):2415-23. DOI: 10.1021/nn800590n
Source: PubMed


Highly fluorescent conjugated polymer dots were developed for demanding applications such as fluorescence imaging in live cells. These nanoparticles exhibit small particle diameters, extraordinary fluorescence brightness, and excellent photostability. Single particle fluorescence imaging and kinetic studies indicate much higher emission rates (approximately 10(8) s(-1)) and little or no blinking of the nanoparticles as compared to typical results for single dye molecules and quantum dots. Analysis of single particle photobleaching trajectories reveals excellent photostabilityas many as 10(9) or more photons emitted per nanoparticle prior to irreversible photobleaching. The superior figures of merit of these new fluorescent probes, together with the demonstration of cellular imaging, indicate their enormous potential for demanding fluorescence-based imaging and sensing applications such as high speed super-resolution single molecule/particle tracking and highly sensitive assays.

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    • "Furthermore, cyanine dyes are susceptible to high levels of photobleaching and molecular quenching that can limit applications and reproducibility. There are now several alternative fluorescent labels available, commonly referred to as second generation labels, for example, quantum dots [3], dye doped polystyrene [4]/silica particles [5] and fluorescent noble metal clusters [6] that overcome many of these limitations. Therefore, if silica NP labels are to be fully utilised, in both laboratory and point of care settings, it is critical that they can be doped with far-red dyes, such as Cy5 and FR670, in an efficient and reproducible manner. "
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    ABSTRACT: Silica nanoparticles (NPs) doped with far-red fluorescent cyanine dyes, Cy5 and FR670, were prepared using the microemulsion method. The effects of nucleation pathway on dye loading and NP morphology were investigated using UV–Vis spectroscopy and transmission electron microscopy for different combinations of three surfactants, Triton® X-100, AOT and NP-5. Successful synthesis of monodispersed NPs with efficient dye loading was achieved using an intramicellar nucleation pathway combined with a negatively charged surfactant. For effective bioconjugation NPs were coated with a silica shell using either the microemulsion or the Stöber method. To maximise fluorescence intensity a series of NPs were doped with different amounts of dye ranging from 0.5 to 6% (w/w). At dye loadings of 0.5 and 0.25% (w/w) for Cy5 and FR670, respectively, NPs were 72 and 87 times more fluorescent than free dye labels. For Cy5 the change in fluorescence intensity with dye loading matched closely with a standard model for homo Förster resonance energy transfer (hFRET). A significant drop in fluorescence lifetime inside the NPs with increased dye loading was also observed and correlated with changes in energy transfer and quantum efficiency. Cy5 dye doped NPs were tested as biolabels in a fluorescence immunoassay to detect C-reactive protein, which is a recommended biomarker for cardiovascular disease. The NP label assay showed approximately an order of magnitude improvement in limit-of-detection when compared to a free dye assay.
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    • "Generally, this can be achieved by encapsulating numerous molecular dyes inside biocompatible polymer nanoparticles [5]. It can also be achieved by using intrinsically fluorescent p-conjugated polymers [6], encapsulated inside nanoparticles [7] or formulated as polymer dots (Pdots) which have a much smaller size (5e25 nm) than nanoparticles [8]. An alternative strategy to get fluorescent polymer probes of small size consists in covalently binding dyes along a biocompatible polymer chain [9] [10]. "
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    • "Compared with inorganic solar cells, the disadvantage of limited light absorption and low charge carrier mobility within the thin film which leads to low PCE makes PSCs stay far away from commercial use. [10] [11] [12] [13] [14] [15] [16] Highly efficient solar cells require the absorption of photons over the broadest possible range of the solar spectrum followed by effective generation and collection of charge carriers. As a consequence, great efforts have been made to raise the PCE of PSCs. "

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