Affinity biosensors based on solid supported lipid membranes.: Their structure, physical properties and dynamics

The paper describes results of study of physical properties of novel affinity biosensor based on self-assembled metal supported systems of biotinylated bilayer lipid membranes (s-BLM). In this biosensor, avidin modified monoclonal antibody originating from E2/G2 clone (A-MAb) was used as the antibody and 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide as the antigen (Ag) to provide an immunological interaction that could be transduced by the presented s-BLM sensor. An increase of membrane conductance, kappa, an increase of elasticity modulus in the direction perpendicular to the membrane plane, E-perpendicular to and decrease of membrane capacitance, C, were experimentally proved by the addition of Ag to the s-BLM and used as a sensor response. The analysis of experimental results showed that interaction of Ag with the A-MAb resulted in changes of membrane mechanical properties, which might be connected with the induction of conformational changes in the A-MAb complex after binding with Ag, Binding of A-MAb to the free standing BLM as well as interaction of 2,4-D with A-MAb modified BLM resulted in increase of relaxation times of dipole moments reorientation as revealed from capacitance relaxation experiments. The physical properties of the s-BLM depend on the metal support on which the membrane is formed. This has been proved by comparison of the properties of s-BLM formed on the tip of freshly cut polymer coated stainless steel wire and on thin gold layer. (C) 1998 Elsevier Science S.A. All rights reserved.