Studies on the Preparation of Nanoparticles from Betulin-Based Polyanhydrides

Nanoparticles were obtained by nanoprecipitation and by emulsion solvent evaporation (ESE) method. In the ESE method, the size of the particles depended on the type and concentration of surfactant (in the water phase) and the polymer concentration (in the organic phase). The best results were obtained with ionic surfactants, however, the use of such compounds may accelerate the degradation process of polymers. In the nanoprecipitation method, the ratio of solvent (methylene chloride) to non-solvent (hexane) has a significant influence on the particle size. The smallest particles were obtained with a solvent to non-solvent ratio of 1:150.