Diacetylene Chelator Lipids as Support for Immobilization and Imaging of Proteins by Atomic Force Microscopy

Chelator lipids represent a powerful and flexible tool to immobilize, orient, and crystallize histidinetagged proteins at interfaces. To produce stable two-dimensional polymers that are biofunctional, we synthesized diacetylene lipids carrying a metal-chelating headgroup. These lipids were characterized at the air-water interface with respect to their thermodynamic properties, complex formation, and photopolymerization using film balance techniques combined with epi-fluorescence microscopy. Polymerized monolayers were transferred onto solid supports and reversible binding of histidine-tagged protein/DNA complexes was followed by atomic force microscopy. The versatility of the chelator lipid concept may open the possibility to examine structure and function of proteins or multiprotein assemblies under native conditions and in real time by scanning probe microscopy.