Entrapment of Highly Active Membrane-Bound Receptors in Macroporous Sol−Gel Derived Silica

The immobilization of membrane-associated proteins remains a challenging task. Herein, we report on the entrapment of two classes of membrane-bound receptors into sol-gel derived silica. Both nicotinic acetylcholine receptor (nAChR), a ligand-gated ion channel, and dopamine D(2Short) receptor (D2R), a G-protein coupled receptor, were entrapped into a series of sol-gel derived nanocomposite materials. In cases where the silica had a bimodal pore size distribution wherein both mesopores and macropores were present, the two receptors showed 40-80% of solution activity over periods of at least 1 month. Furthermore, the dissociation constants of entrapped nAChR and D2R for binding to known agonists and antagonists were very close to the values obtained for free receptors in solution. These results indicate that membrane-bound receptors entrapped into bimodal meso/macroporous silica should provide a useful platform for the development of bioanalytical devices such as bioaffinity columns or microarrays, which could aid in diagnosis and high-throughput drug screening.