Abstract
The techniques available to prepare biodegradable nanoparticles (nanospheres and nanocapsules) from preformed polymers are reviewed. Although there is abundant literature on this topic, only a few focus on the thorough analysis of preparative procedures. In particular, four techniques are discussed in terms of their technological advantages and drawbacks: emulsijication evaporation, solvent displacement, salting-out, and emulsijication difision. The proposed mechanism of nanoparticle formation for each technique is described from a physicochemical perspective. The eflects of preparative variables on nanoparticle size and drug-entrapment efficiency are also discussed.