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We report a one-step process for decorating poly(trimethylene terephthalate) (PTT) nanofibers with CdSe/ZnS core/shell quantum dots (QDs). Using the QD-decorated PTT nanofibers with diameters of 400-800 nm as active subwavelength waveguides, their high photostability for 630 nm red light and low absorption coefficient down to 2.6 cm [?] 1 were characterized by both evanescent waveguiding excitation and irradiation excitation. Compared with the irradiation excitation, a 200 times enhancement was obtained from the active subwavelength waveguides under the evanescent waveguiding excitation. [ABSTRACT FROM AUTHOR]

There has been increased interest in the use of polymeric nanoparticles as carriers for near-infrared fluorescence (NIRF) dyes for cancer diagnosis. However, efficient delivery of nanoparticles to the tumors after systemic administration is limited by various biobarriers. In this study, we investigated the pharmacokinetics, biodistribution, and tumor uptake of sub-nanometer sized polymeric nanoparticles (<100 nm in diameter) coated with polyethylene glycol in tumor-bearing mice. To facilitate our studies, these particles were labeled with gamma emitter indium-111. We found that two NIRF nanoparticles having the same size ([?]20 nm) and chemical composition but different structures (i.e., hydrogel versus core-shell nanolatex), or the same core-shell nanolatex particles with different sizes (20, 30, and 60 nm), had different blood circulation times, biodistribution, and tumor uptake. Interestingly, the tumor uptake of the nanolatex particles correlated well with their blood residence times (R2 = 0.95), but similar correlations were not found between nanogel and nanolatex particles (R2 = 0.05). These results suggest that both the blood circulation time and the extent of hydration of the nanoparticles play an important role in the tumor uptake of nanoparticles. Prolonged blood circulation of these NIRF nanoparticles allowed clear visualization of tumors with g-scintigraphy and optical imaging after intravenous administration. A better understanding with regard to how the characteristics of nanoparticles influence their in vivo behavior is an important step towards designing NIRF nanoparticles suitable for molecular imaging applications and for efficient tumor delivery. [ABSTRACT FROM AUTHOR]