Histidine-tagged amphiphiles for the reversible formation of lipid bilayeraggregates 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 chromato graphy technology, which depends on the reversible formation of complexes b etween 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 thioalkan es (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 plana r 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 o n the lipids and the ionic strength of the buffer solution used. Surface pl asmon resonance is used to monitor the formation of lipid layers. The synth esis of the His-lipid and the characterization of its monolayer layer formi ng and binding properties on a Langmuir trough are also described.