Histidine-Tagged Amphiphiles for the Reversible Formation of Lipid Bilayer Aggregates on Chelator-Functionalized Gold Surfaces

A new strategy for the reversible formation of supported lipid bilayers is introduced. It uses an extension of immobilized metal ion affinity chromatography technology, which depends on the reversible formation of complexes between metal ion binding chelator groups and oligohistidines. Lipid layers containing hexahistidine-derivatized amphiphiles (His-lipids) are anchored to a self-assembled monolayer (SAM) containing synthetic chelator thioalkanes (CTA). The control over the density of anchor sites on the substrate and over the surface wetting properties leads to a high degree of flexibility in the design of extra free space between the substrate and the lipid layer for the reconstitution of proteins. His-lipids can be used to anchor planar lipid layers or layers of intact lipid vesicles to CTA SAMs. The form of the lipid layers (planar bilayer or vesicles) is determined by the charge on the lipids and the ionic strength of the buffer solution used. Surface plasmon resonance is used to monitor the formation of lipid layers. The synthesis of the His-lipid and the characterization of its monolayer layer forming and binding properties on a Langmuir trough are also described.