Silica colloidal crystals as three-dimensional scaffolds for supported lipid films

This report describes the assembly of laterally diffusive lipid layers within the pores of colloidal crystals for potential application in membrane-based sensing. The amount of lipid encapsulated within colloidal crystals depends upon the method used to introduce the lipid to the crystalline substrate. Relative to a planar supported lipid bilayer, lipid loading in a 6.6 microm thick crystal was 15-73 times greater, as observed by fluorescence microscopy. Protein adsorption studies indicate that the crystal pores are open and that the silica surface of the crystal is passivated with respect to adsorption of a model protein when coated with POPC. Furthermore, the mesoporous environment of the colloidal crystal is found to protect lipid films from drying and rehydration processes that destroy planar supported lipid bilayers. The potential of colloidal crystal encapsulated lipid films for chemical sensing is demonstrated by a model protein binding assay.