Lipid nanoparticles were prepared by probe sonication of the constituent lipids and a sterile solution of Pluronic F-127 (2 wt%) in the appropriate culturing media (De Man, Rogosa and Sharpe media (MRS) or Luria-Bertani broth (LB)). The pH of lipid dispersions varied according to the lipid composition and the type of culturing media used as this was necessary for the normal growth of bacterial strains; as such the pH was monitored rather than buffered and taken into account during analysis (Table ). The structured lipid particles were 100 -300 nm in diameter with a moderate size distribution (Table ).