Fluorescence Imaging of Nanoparticle Uptake

After 6 h of orally administering 50 mg of either DiR or PKH26 fluorescent dye (Sigma) labelled GDNP, mice were sacrificed and the small intestine, colon, MLN, spleen and liver tissues were collected for imaging. DiR fluorescent signal was detected and measured using the Imaging Station Pearl Impulse (Li-COR Biosciences). The labeled GDNP in the gut of mice were visualized using an Odyssey CLx Imaging System (Li-COR Biosciences). PKH26 signal in frozen tissue sections was observed using a confocal laser scanning microscopy system (Nikon, Melville, NY). The method was previously described 14 (link). For fat uptake, nanoparticles were isolated from the high-fat diet-fed mice using our exosome isolation protocol 20 (link). Nanoparticles were labeled with DIR and orally administered to mice. After 6 h of oral administration, mice were sacrificed, the intestines harvested, flushed twice with PBS and scanned for DIR signals.