The casein micelle as an encapsulation system for triclosan: Methods of micelle dissociation, encapsulation, release, and in vitro delivery

This dissertation reports on the use of the casein micelle as an encapsulation and potential delivery system for a low molecular weight hydrophobic compound, triclosan. The ability of the casein micelle to serve in this capacity was tested in a series of experiments investigating: 1) micelle dissociation to expose hydrophobic binding sites of interaction, 2) encapsulation of triclosan, 3) the release of triclosan under various conditions, and 4) the intercellular delivery of triclosan to human liver cells in vitro for the inactivation of a malaria-causing parasite. Casein micelle dissociation and reassociaiton was achieved through high pressure homogenization and solvent-mediated pressure-induced dissociation. Triclosan was found to naturally associate to casein micelles in skim milk (up to 70%) and this association is enhanced by 30% at homogenization pressures reaching 300 MPa. The release of triclosan is governed by the disruption of micelle integrity, i.e., the enhancement casein-solvent interactions, where triclosan likely exists as a triclosan-protein complex as opposed to free triclosan. In the presence of milk, the release of triclosan is prevented in simulated gastric solutions but released in a simulated intestinal solution, demonstrating the ability of to milk protect triclosan from the acidic environment of the stomach and promote its release in the intestine, a measure of bioaccessibility. The intercellular delivery of triclosan was most affected by the type of milk protein. Triclosan transported within β-casein isolates where most sufficient in preventing the growth and development of Plasmodium berghei, the rodent malaria parasite, in human liver cells. Triclosan carried within milk digestates were also efficient in delaying parasite growth, whereas triclosan carried within milk serum by serum proteins where completely ineffective. Triclosan in the presence of milk also provided a protective effect on host cells from the acute toxicity of triclosan in free form. These experiments introduced new functional properties of the casein micelle. The casein micelle has the ability to serve as an encapsulation system and casein proteins, as a potential delivery system. This introduces new functional properties of the casein micelle for use novel usage within the food, pharmaceutical, and/or cosmetic industry.