Entrapment of membrane proteins in sol-gel derived silica

The last decade has seen a revolution in the area of sol-gel-derived biomaterials since the demonstration that these materials can be used to encapsulate biological species such as enzymes, antibodies and other proteins in a functional state. In particular, recent years have seen tremendous progress on the use of sol-gel entrapment for immobilization of biological bilayer lipid membranes (BLMs) and membrane bound receptors. This is a particularly impressive feat, given the inherently low stability of membrane receptors and the need to stabilize an amphiphilic BLM to maintain receptor function. This review provides a summary of the various methods currently used for immobilization of membrane-bound proteins, a description of the advances in sol-gel technology that led to the ability to entrap viable receptors, and an outline of the current state of the field with respect to membrane proteins entrapped in silica. Advantages of sol-gel entrapment relative to alternative immobilization strategies are highlighted and potential applications of entrapped receptors, including platforms for biosensing, drug screening and energy storage, are described. Finally, suggestions are made regarding future studies that are likely to be important for further developing this technology.