Factors affecting protein release behavior from surfactant–protein complexes under physiological conditions

Protein release behavior from its complex with edible surfactants was investigated under physiological conditions using hen egg lysozyme and Aspergillus niger glucose oxidase as model proteins. It revealed that protein release rates could be controlled by hydrophobicity of surfactants and the molar ratio of proteins to surfactants in the preparation of the complexes. Evaluation of functional integrity of a protein on the basis of specific activity of an enzyme released from the complex suggested that lower hydrophobicity of surfactants led to higher retention of catalytic activity. In addition, it was found that protein release rates from the complexes were correlated with the aqueous droplet size of water-in-oil emulsions in the preparation of the complexes. The results suggest the potential of surfactant–protein complexes in pharmaceutical formulations for mucosal delivery of therapeutic proteins.