The amphiphilic biodegradable polymer surfactant, poly(ethylene oxide monooleate)-block- poly(D,L-lactide) (MOPEO-PLA), was shown to form microemulsions in organic solvent and to dissolve cytochrome c into their microemulsions at high concentration with native form. The microemulsions dissolving cytochrome c provided a new preparation route of polylactide microcapsules enclosing cytochrome c, which exhibited high entrapment of proteins in the microcapsules and sustained long-term release. A MOPEO-PLA microemulsion system would provide a new encapsulation system with a biodegradable polymer matrix for delivery of proteins and peptides.
