Cationic biodegradable particles: Comparison of one or two step processes

Emulsification-diffusion was used to obtain cationic poly(d,l-lactic acid) (PLA) particles. Two formulations were compared: one in which all ingredients were added all together and the second based on a two step precedure involving: (i) PLA particle elaboration by emulsification-diffusion, (ii) post functionalization with a polycation. Chitosan was selected as a polycation. First the impact on the elaboration process of the presence of the polysaccharide was assessed which showed that the external phase had to be acidified to yield particles and reduced in volume by a factor two in comparison to the original recipe in the absence of polycation. The incorporation of chitosan during the one step procedure and its core/surface distribution were investigated. It appeared that chitosan was maily buried within the core of the particle along with the non-ionic surfactant PF68, a polyethylenoxide-polypropylene oxide-polyethylene oxide triblock copolymer. The presence of chitosan increased also the incorporation of PF68 as compared to particles obtained in the absence of polycation.Despite their low zeta potentials, the particles obtained via the one step process could interact with plasmid DNA, even though this binding was less efficient than with particles obtained via the two step approach.