Hemoglobin niobate composite based biosensor for efficient determination of hydrogen peroxide in a broad pH range

Inorganic layered niobates (HCa₂Nb₃O₁₀) were used as immobilization matrices of hemoglobin (Hb) because of their tunable interlayer spaces, large surface areas and good biocompatibilities. A pair of well-defined, quasi-reversible cycle voltammertric peaks were obtained at the Hb-HCa₂Nb₃O₁₀ modified pyrolytic graphite electrode, suggesting that the layered niobates facilitate the electron transfer between the proteins and the electrode. Hb-HCa₂Nb₃O₁₀ modified electrode exhibited electrocatalytic response for monitoring H₂O₂ with a large linear detection range from 25 μM to 3.0 mM and a relatively high sensitivity of 172 μA mM^-1 cm^-2. Based on the stabilizing effect of the layered niobates, Hb-HCa₂Nb₃O₁₀ modified electrode can detect H₂O₂ in strongly acidic and basic solutions with pH of 1-12, which greatly expands the application fields of biosensors.