Assembly of poly(methacrylate)/purple membrane lamellar nanocomposite films by intercalation and in situ polymerisation

Abstract

Thin films comprising ordered stacks of purple membrane (PM) sheets containing the light-driven proton pump bacteriorhodopsin (BR) were infiltrated with methacrylic acid (MA) monomers to produce lamellar bionanocomposites. Subsequent in situ polymerization and crosslinking of the guest MA molecules resulted in partially intercalated poly(methacrylate)/PM freestanding films, which showed increased stability in water, structural integrity and enhanced resistance to ethanol degradation compared with PM control films or non-polymerized MA/PM layered nanocomposites. Studies on photocycle kinetics confirmed that the polymerized PM films were functionally active, and showed an increase in the lifetime for the M-state intermediate of the photocycle. The results indicate that nanometre-thin layers of crosslinked poly(methacrylate) can be synthesized in situ between the PM sheets to produce novel functional bionanocomposites with proton transfer and photochromic properties.