Phagocytic uptake and cytotoxicity of solid lipid nanoparticles (SLN) sterically stabilized with poloxamine 908 and poloxamer 407

Solid lipid nanoparticles (SLN) as alternative intravenous colloidal drug carriers were produced by high pressure homogenisation of melted Lipids (glyceroblehenate, cetylpalmitate). Their surface was modified by using hydrophilic poloxamine 908 and poloxamer 407 block-copolymers in order to reduce the phagocytic uptake by the reticuloendothelial system (RES) after i. v. injection. The phagocytosis reducing effect of the polymers was investigated in vitro in cultures of human granulocytes, uptake was quantified by chemiluminescence. Modification of the SLN with poloxamine 908 and poloxamer 407 reduced the phagocytic uptake to appr. 8-15% compared to the phagocytosis of hydrophobic polystyrene particles. The modified SLN proved more efficient in avoiding phagocytic uptake than polystyrene particles surface-modified with these blockcopolymers (48% and 38%, respectively). Viability determinations revealed the SLN to be 10 fold less cytotoxic than polylactide nanoparticles and 100 fold less than butylcyanoacrylate particles.