Broad Based Tissue Uptake of Polycationic Near-Infrared Polymeric Nanoparticles in Living Mice

Abstract

A near infrared (NIR) fluorescent polymeric nanoparticle, commercialized under the name X-Sight 761 (X761), was tested for compatibility with pre-clinical in vivo imaging applications. In one experiment, an optical clearance profile was obtained by performing whole animal fluorescence imaging over the course of 48 hours on mice injected intravenously with X761. In a second trial, a temporal biodistribution was assessed by conducting necropsy and ex vivo analysis of X761 tissue accumulation at selected time points over a 48 hours period after i.v. injection. Taken together, the data demonstrate a sustained distribution of X761 into all major tissues over the time course, with an extremely low net clearance from the animal. This unique behavior is attributed to cell uptake mediated by the polycationic surface of X761. These properties negate the use of X761 as a reporter within a classical targeted molecular probe construct, in which selective concentration at a target site and rapid clearance from background tissues are needed to develop contrast. Nevertheless, the brightness and stability of X761 is well suited for a range of other applications, ranging from broad based in vivo drug delivery to in vitro fluorescence assays.

In Vivo Fate of Carbon Nanotubes with Different Physicochemical Properties for Gene Delivery Applications

“…Ex vivo fluorescence imaging is able to provide a reliable semiquantitative assessment of the amount of fluorophore present in each organ. 61 Results (Figures 7 and S7A) show that lung accumulation of s-fCNTs was statistically higher than that observed in almost all the other organs (except for the gut). fCNTs show a similar behavior with a statistically higher lung signal than the other organs (except no statistical difference compared with the liver and gut).…”

“…Ex vivo fluorescence imaging is able to provide a reliable semiquantitative assessment of the amount of fluorophore present in each organ . Results (Figures and S7A) show that lung accumulation of s-fCNTs was statistically higher than that observed in almost all the other organs (except for the gut).…”