A hydrogen biosensor made of clay,poly(butylviologen), and hydrogenase sandwiched on a glass carbon electrode

A hydrogen gas (H(2)) biosensor was developed in which hydrogenase (H(2)ase) was immobilized and sandwiched between two layers of a montmorillonite clay and poly(butylviologen) (PBV) mixture on a glass carbon electrode. The immobilized PBV efficiently enhanced the electron transfer among the electrode, H(2)ase, and methyl viologen in solution. Both PBV and methyl viologen acted as the electron carrier in the clay-PBV-H(2)ase modified electrode. The clay-PBV-H(2)ase electrode catalyzed the oxidation of H(2) to protons (H(+)) with the electrons being transferred by viologen groups to the electrode. The activation energy of this process was 38+/-2 kJ/mol at pH 7. The catalytic current of the clay-PBV-H(2)ase electrode increased linearly when exposed to increasing concentrations of H(2) gas. In contrast, this electrode showed no activity when exposed to three combustible compounds, namely, carbon monoxide, methane and methanol. The optimum pH range for the oxidation of H(2) by the clay-PBV-H(2)ase electrode was from 7 to 10. Electron transfer process in the clay-PBV-H(2)ase electrode is discussed.