Nanoencapsulation of Alpha-linolenic Acid with Modified Emulsion Diffusion Method

Nanocapsules of alpha-linolenic acid (alpha-LA) were prepared by a modified emulsion diffusion technique with encapsulation efficiency of 93%. Polylactic acid (PLA) was used as the encapsulating polymer with acetone and ethyl acetate as organic solvents, and Tween 20, gelatin and Pluronic-F68 in water as stabilizers. Two ratios of organic to aqueous phases were used with each solvent and stabilizer. Nanocapsule dispersions with a particle size less than 100 nm and a zeta potential as high as 33 mV were obtained as verified by scanning electron microscopy and the dynamic light scattering technique respectively. Both particle size and zeta potential were influenced by such preparation conditions as the type of stabilizer, type of organic solvent and the organic to aqueous phase ratio. Acetone was superior to ethyl acetate, and Tween 20 was superior to each of Pluronic-F68 and gelatin in obtaining smaller, less aggregated nanocapsules. An organic to aqueous phase ratio of 1:5 was shown to be more suitable for the formation of smaller nanocapsules, particularly when acetone was used as the organic solvent.