Novel Antimicrobial Phenolipids: Functionality, Mechanisms of Action and Delivery Systems Design

Surfactant systems are commonly used in the petroleum industry, cosmetics, foods, and textile industry. Micellization, one important characteristic of this system, can be used to aid in the solubilization and delivery of poorly water-soluble compounds in the continuous phase. The solubilization of an insoluble molecule is governed by thermodynamic properties determined by the molecular structure of the involved compounds. In this Ph.D. project, we are interesting in developing and optimizing micellar based delivery systems for the Food Industry by forming functional polymer-micelle complexes.

           Surfactants readily self-assemble and form micelles at a critical micellar concentration (CMC) in order to decrease the free energy of the system. The important feature of micelles as a delivery system is their capability of solubilizing lipophilic material. A critical parameter in the solubilization is the maximum amount of material that can be incorporated or the ‘maximum additive concentration’ (MAC), a parameter that will be determined for a variety of polymer-micelle complexes.

           In the presence of polymers, surfactants have shown to undergo changes in their association behavior (e.g. aggregation numbers, shape of micelles). The formation of these complexes are governed by the molecular properties of the polymer and the surfactant. Numerous studies have shown that addition of appropriate polymers may lower the CMC, reducing the size of spherical micelles, allowing for formation of complexes with mixed surfactant, and transforming large rodlike micelles and vesicles into smaller globular micellar aggregates. The interaction between polymers and micelles is particularly strong, if both carry charges. While some of the structural interactions are well know, very little is known with respect to changes in the ability of micelles to solubilize lipophilic compounds once they have formed a polymer-micelle complex.

The purpose of this study is therefore to provide a better understanding of the solubilizing characteristics of polymer-micelle complexes composed of a variety of polymer surfactant combinations e.g. nonionic polymers – nonionic surfactants, ionic polymers – nonionic surfactants, nonionic polymers – ionic surfactants and finally ionic polymers and ionic surfactants. From an application point of view we intend to elucidate in addition on the influence of environmental parameters (temperature, pH, and ionic strength) on the ability these complexes to carry lipophilic functional ingredients for the Food Industry.