RESUMO
Poly(lactic-co-glycolic acid) particles encapsulating albumin were produced by the double emulsion technique (Water in Oil in Water). The diffusion coefficient and therefore the release rate were quantified as a function of the operating conditions. The second Fick's law of diffusion was used by applying the entire particle size distribution to estimate the diffusion coefficient. The stirring speed, polyvinyl alcohol concentration in the external water phase and the water to oil ratio in the internal emulsion were varied. It was found that the release rate increased while decreasing the particle size. Therefore, all the process parameters that are assumed to affect the particles size--such as the stirring speed or marginally the polyvinyl alcohol concentration--are supposed to affect the release rate. Finally, decreasing the water to oil ratio in the internal emulsion was found to increase the particle porosity and therefore to increase the diffusion coefficient.
