Poly-(D,L-lactide-co-glycolide) (PLGA) nanoparticles have been widely studied for drug delivery. The aim of this study is to determine how cellular uptake of these nanoparticles is influenced by different surface properties, incubation time, particle concentration and cell types. Spherical coumarin-6 loaded PLGA nanoparticles with a size of about 100 nm were synthesized through solvent emulsion evaporation and nanoprecipitation methods. In vitro cellular uptake efficiency was determined using human bronchial epithelial cells (BEAS-2B) and murine monocyte-derived macrophage (RAW264.7) cells. PLGA nanoparticles were incubated with these cells in a concentration range of 10-300 μg/ml for different time periods. The results show that cellular uptake decreased for nanoparticles surface coated with PVA surfactant and was especially limited for severely aggregated particles. At higher particle concentration, the total amount of particles taken up by cells increased while the uptake efficiency decreased. In addition, cells could take up more particles with longer incubation time, although the uptake rate decreased gradually with time. Finally, RAW264.7 cells show increased uptake compared to BEAS-2B cells. The information drawn from this study would provide important clues on how nanomaterials interact with cells and how these interactions can influence biocompatibility or toxicity.
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