Cytotoxicity of magnetite-loaded polylactide, polylactide/glycolide particles and solid lipid nanoparticles

Particles from polylactide (PLA), polylactide/glycolide (PLA/GA) and solid lipid nanoparticles (SLN) were produced and loaded with different amounts of magnetite, The in vitro cytotoxicity was determined to assess their toxicological acceptance as intravenous formulation for magnetic resonance imaging and as potential carrier for drug targeting. Viability determinations were performed in suspensions of human granulocytes using the dimethylthiazolyl-diphenyltetrazolium (MTT) test. Particle internalization by the granulocytes was followed using luminol enhanced chemiluminescence (CL). The effective concentrations to reduce the viability to 50% (ED 50%) were 0.38% and 0.30% for high and low molecular weight PLA, 0.15% for PLA/GA. The mechanism of toxicity is the intracellular uptake, with the highest toxicity being observed for the faster degrading polymers, low molecular weight PLA and PLA/GA. The solid lipid nanoparticles proved to be the least cytotoxic preparation with an effective concentration (ED 50%) above 10%.