Preparation and purification of cationic solid lipid nanospheres--effects on particle size, physical stability and cell toxicity.

Cationic solid lipid nanospheres (SLN) were prepared by the microemulsion technique with polysorbate 80 (Tween 80) and butanol as surfactants. The SLN (diameter 100-500 nm, zetapotential around +15 mV) consisted mainly of stearylamine (SA) and different triglycerides. Three different purification methods, ultrafiltration, ultracentrifugation and dialysis, were investigated and compared with the cellular toxicity and physical stability of the dispersions. The cell toxicity was dependent on both the SLN composition and the purification method. Dialysis was found to easily and efficiently remove excessive surfactant determined by dynamic light scattering (DLS), leading to reduced cell toxicity and increased physical stability of the SLN on storage. The cationic SLN might constitute a promising DNA delivery system.