Electrokinetic properties of poly-ε-caprolactone-based nanoparticles prepared by nanoprecipitation and emulsification-diffusion methods: a comparative study

The aim of this work is to investigate the influence of the preparation method on the surface charge and electrokinetic properties of poly-ε-caprolactone-based particles using poloxamer 188 as stabilizing agent. To target such objective, two processes (the nanoprecipitation and the emulsification-diffusion) are used to prepare well-defined nanospheres ranging in hydrodynamic diameters from 100 to 200 nm. The effect of the materials used on the particle zeta potential is systematically studied to compare the two preparation methods. The polarity of the organic solvent directly affects the zeta potential of particles prepared via the emulsification-diffusion method. The results obtained suggest that the aqueous phase used for preparing particles affects the possible re-arrangement of polymers during the emulsification step. As the aqueous phase is saturated with the organic solvent, the polar and the non-polar moieties of the polymer chains might be re-conformed following organic solvent diffusion from the particle core to the continuous phase. Regarding the nanoprecipitation process, the electrokinetic properties of the particles were found to be organic solvent independent, but principally affected by the pH and the salinity of the aqueous phase used during the particle preparation.