In situ evading of phagocytic uptake of stealth solid lipid nanoparticles by mouse peritoneal macrophages

Stealth solid lipid nanoparticles ( SSLN) were prepared and evaluated for the effect of evading phagocytic uptake by mouse peritoneal macrophages in situ. Fluorescent SSLNs were prepared by emulsion/ evaporation with rhodamine B as the fluorescent marker and polyoxyethylene stearate as stealth agent in a stearic acid matrix. Macrophages were induced chemically through intraperitoneally injecting 1% sodium thioglycolate. After 4 days of cultivation, SSLNs suspension was injected intraperitoneally and phagocytosis taken out in situ. At definite time intervals, peritoneal fluid was drawn out and analyzed by flow cytometer. Maximium uptake by macrophages was observed at 2 hr after injection of nanoparticles. At all time intervals, phagocytic uptake of Solid lipid nanoparticles ( SLNs) was better than SSLNs. Longer and dense polyethylene glycol chains led to reduced uptake by macrophages. Both SSLNs and SLN had uptake by macrophages to some extent, and the in situ model was suitable for evaluating interactions between cells and nanoparticles.