Effect of O/S/W process parameters on 17beta-EV loaded nanoparticles properties.

ABA triblock copolymer, poly(ethylene glycol)-poly(butylene adipate)-poly(ethylene glycol) (PEG-PBA-PEG) could form micelle-like nanoparticles due to their amphiphilic characteristic. The mechanism of nanoparticle formation is based on the modified oil in water (O/W) emulsion by emulsifying acetone solution of copolymer containing different amount of dissolved 17beta-estradiol valerate (17beta-EV) in olive oil into the external water phase i.e. oil(1) and oil(2) in water (O & O/W). The acetone-evaporated nanodroplets involved an inner oil phase, an outer water phase and a solid shell between two phases, so called O/S/W nanocapsules. In order to control the nanocapsules size, the effect of various emulsion parameters such as the concentration of polymer, drug content, polymer/oil weight ratio and concentration of surfactant on morphology were studied. Particle size, their distribution and release profile of nanocapsules were investigated too. This study gave some important information about the structure, mechanism of formation, release profile and the physical properties (i.e. encapsulation efficiency, drug loading, nanoparticles yield) of nanocapsules. To investigate the influence of PEG chain on the stability of produced nanodroplets, nanocapsules were also prepared with and without Tween 80 as surfactant.