Oriented purple membrane multilayers of halobacteria fabricated by langmuir–blodgett and electrophoretic sedimentation techniques†

Organised films containing oriented patches of purple membranes and consisting of 15–75 layers and approximately 1000 layers were fabricated by the Langmuir–Blodgett and electrophoretic sedimentation techniques respectively. ‘Surface pressure vs. molecular area’ isotherms for monolayers of purple membranes suspended in hexane and deposited on the air/water interface were studied. Circular dichroism and absorption spectroscopy were used to investigate the effect of an organic solvent on the chromophore binding site in the purple membranes. Kinetic methods based on flash excitation were employed to determine the influence of the film deposition conditions on the photoelectric response of bacteriorhodopsin and on the M412 intermediate relaxation. Structural characteristics for multilayers prepared from water and hexane purple membrane suspensions were determined by low-angle X-ray scattering. The influence of the layer deposition conditions on the electrical, physical and photoelectrical properties of ordered structures containing bacteriorhodopsin is discussed.