Microspheres as delivery systems for the controlled release of peptides and proteins

Microencapsulation of peptides and proteins has recently become a relevant alternative to develop novel drugdelivery systems. Among techniques designed to microencapsulate substances of different nature, the interfacial polymerization, spray-drying and solvent evaporation techniques are those most widely studied for encapsulation of biomolecules. The solvent double emulsion-evaporation procedure is most commonly applied for this kind of product that is available in the market. On the other hand, this method of protein encapsulation is a rather complex process, involving several factors that determine the properties of the final product and the stability of the encapsulated molecule. In this paper, we offer an updated overview on the use of microspheres as systems for the controlled release of proteins and peptides, the main techniques used for microencapsulation of such biomolecules, and the parameters considered for characterizing the microspheres and the encapsulated protein. Experimental conditions influencing their stability during the solvent double emulsion/evaporation microencapsulation procedures, and strategies used to preserve and stabilize the physicochemical and biological properties of the encapsulated proteins are also discussed.