Co-immobilization of polymeric luminol, iron(II) tris(5-aminophenanthroline) and glucose oxidase at an electrode surface, and its application as a glucose optrode

The anodic polymerization of 3-aminophthalhydrazide (luminol) and iron(II) tris 5-aminophenanthroline (Fe(phen-NH₂)₃²⁺) has been reported in this paper. A bilayer electrode was developed based on these polymers and the ITO conductive glass (denoted ITO|Fe(phen-NH₂)₃²⁺|luminol electrode). This electrode emitted light (λ_em: 430 nm) as it was brought into contact with H₂O₂. At pH 10, the resulting electrochemiluminescence (ECL) showed a linear relationship with the concentration of H₂O₂ in the range of 10 μM-1 mM. This bilayer electrode also showed an application potential for the detection of glucose after being further modified with glucose oxidase (denoted ITO|Fe(phen-NH₂)₃²⁺|luminol|GOx electrode). Although the resulting ECL decayed more rapidly in concentrated glucose solutions (e.g., 1 M) because of the consumption of luminol during use, the decay became less severe in diluted glucose solutions (e.g., 10 mM). According to the flow injection analysis, a linear relationship existed between the ECL and the concentration of glucose from 10^-5-10^-3 M at pH 9. The detection limit could reach a level of 5 × 10^-5 M at this pH.