Study of the electrode process of hemoglobin at a polymerized azure A film electrode

The electrochemically polymerized azure A film electrode is reported. The resulting film on a platinum electrode surface was analyzed with electron spectroscopy for chemical analysis (ESCA). The heterogeneous electron transfer processes of hemoglobin at the polymerized azure A film electrode have been investigated using in situ UV‐visible spectroelectrochemistry. The formal potential (E°′) and electron transfer number (n) of hemoglobin were calculated as E = 0.088 V versus NHE (standard deviation ±0.5, N = 4) and n = 1.8 (standard deviation ±0.5, N = 4). Exhaustive reduction and oxidation electrolysis are achieved in 80 and 380 seconds, respectively, during a potential step between −0.3 and +0.3 V. A formal heterogeneous electron‐transfer rate constant (ksh) of 3.54(±0.12) × 10−6 cm/s and a transfer coefficient (α) of 0.28(±0.01) were obtained by cyclic voltabsorptometry, which indicated that the poly‐azure A film electrode is able to catalyze the direct reduction and oxidation of hemoglobin.