Slow and remanent electric polarization of adsorbed BSA layer evidenced by neutron reflection

Using neutron reflectivity together with an appropriate electrochemical cell, we have studied the effects of transverse electric field on the Bovine Serum Albumin (BSA) monolayer initially adsorbed at the interface of the aqueous solution and a conductive doped-silicon wafer. Depending on the sign of the initial potential, a second layer is adsorbed on top of the first whereas a subsequent reversal of potential has no effect. We show that this behavior reveals the slow and remanent electric polarization of the first BSA layer and suggest an analogy with spin glasses based on the dipolar structure of this protein.