Hydrogenase–poly(viologen) complex monolayers and electrochemical properties in Langmuir–Blodgett films

Abstract

Abstract Mixed monolayers of a hydrogenase (H 2 ase) purified from Thiocapsa roseopersicina and poly(viologen) or hexadecyltrimethylammonium bromide (HTAB) were formed at the air–subphase interface. A larger H 2 ase-occupied area was measured in the H 2 ase–poly(viologen) or in the H 2 ase–HTAB mixed monolayers than that in the pure H 2 ase monolayer. These monolayers were transferred onto solid supports by the Langmuir–Blodgett (LB) method. Spectroscopic measurement indicated that H 2 ase activity was retained in the LB films. Cyclic voltammograms (CVs) of the H 2 ase–HTAB LB film showed two waves at ∼−560 and ∼−530 mV corresponding to the reduction and oxidation potentials of the [4Fe–4S] 2+/1+ clusters of H 2 ase. For the H 2 ase–poly(viologen) LB films, the CV curves showed two broad waves centered at ∼−510 and ∼−480 mV, which correspond to the reversible one-electron process of poly(viologen) 2+/1+ with a small contribution of the [4Fe–4S] 2+/1+ clusters of H 2 ase. Charge transfer properties of the modified electrodes are discussed by use of chronocoulometry.