Abstract
The behavior of polyoxazolines based mixed micelles and lipid nanocapsules on skin surface was studied on nonbiological human skin surface model to assess the formulations potential for topical delivery. Two amphiphilic polyoxazolines, saturated (C16POx15) and unsaturated (C18:2POx15), were used to evaluate the polymer architecture impact on formulations interaction with skin surface. To do so, the formulations spontaneous spreading and their residual film left on surface after manual application was investigated using contact angle measurements and free surface energy determination. The Van Oss model was employed to identify the physicochemical interactions in order to understand how the formulations can change the skin surface properties. In brief, both formulations showed a good affinity with the surface but depending on the polyoxazoline used, the spontaneous formulation spreading was modulated. Overall, the residual film left on the model surface modified the skin model physicochemical properties leading to a better interaction with hydrophilic and polar compounds. Regarding in detail each excipient impact on the surface physicochemical properties further explained the resulting formulation behavior on the skin surface model and highlighted the crucial role of the main component.