Fig. 2.

Tail-vein and RO injections of polymeric nanoparticles yield identical measurements of half-life. (A) Schematic of polymeric nanoparticles composed of a PLA-PEG copolymer encapsulating fluorescent dye and routes of IV administration. (B) Representative fluorescence images of dye-loaded nanoparticles at different concentrations in blood. (C) Circulation half-life measurements after IV administration of fluorescent polymeric nanoparticles using quantitative microscopy (n = 3 mice per group per time point). Error bars represent SEM. Representative end-point (D) flow cytometry histograms from homogenized livers, (E) mean fluorescence intensity (MFI) values for homogenized organs (n = 3 to 4 mice per group per time point; error bars represent SEM), and (F) IVIS analyses of NP uptake in various tissues. (Scale bars, 100 μm.)