Distribution and elimination of coated polymethyl [2-14C]methacrylate nanoparticles after intravenous injection in rats.

Surfactant-coated polymethyl [2-14C]methacrylate nanoparticles had significantly different time-course distribution patterns in rats than noncoated and albumin-coated particles. Blood concentrations of poloxamer 188-coated particles were 70-fold higher after 30 min, and the particles persisted at higher levels in the circulation for up to 2 h. The initial and final liver levels were significantly lower (38% after 30 min, 51% after 7 d) and spleen levels were significantly higher (21% after 30 min, 23% after 7 d) than non-coated particles (74% in the liver and 5% in the spleen after 7 d) and the albumin-coated particles (84% in the liver and 5% in the spleen after 7 d). Specific activity was somewhat higher for the surfactant-coated particles in other organs such as the lungs, kidneys, testicles, ovaries, and lymph nodes. The bovine serum albumin sorption behavior of polymethyl methacrylate nanoparticles was followed under various conditions, and adsorption was found to increase with increasing protein concentration and increasing temperature, reaching a maximum at the isoelectric point of pH 4.9 after approximately 12 h of incubation. The zeta potential of the particles decreased with increasing pH, and the change was more pronounced with the albumin-coated particles.