Nanostructure Formation in Glycerolipid Films during Enzymatic Hydrolysis: A GISAXS Study.

Responsive nanostructured films from food-grade lipids can be valuable for food, pharmaceutical, and biotechnological science. Lyotropic liquid crystalline structures that respond to enzymes in their environment can, for instance, be innovated as drug delivery platforms or biosensors. However, the structural changes that such films undergo during enzymatic reactions with lipase are not yet understood. This work demonstrates the preparation of mesostructured lipid films from the food-grade lipids glycerol monooleate (GMO) and triolein on silicon wafers and their digestion with pancreatic lipase using time-resolved synchrotron grazing incidence small-angle X-ray scattering (GISAXS). The film structure is compared with the corresponding GMO/triolein bulk phases in excess water. Increasing the GMO/triolein ratio in the film makes it possible to modulate the structure of the films from oil coatings to inverse hexagonal and inverse bicontinuous cubic films. Pancreatic lipase triggered swelling of the internal film nanostructure and eventually structural transformation inside the film. Orientation and reorientation of the internal film structure relative to the silicon wafer surface were observed during the preparation of the films and their digestion. The findings contribute to the understanding of self-assembly in thin films and guide the development of enzyme-responsive coatings for the functional modification of various substrates.