Fabrication of an electrochemical H 2 O 2 biosensor based on immobilization of hemoglobin nanoparticles onto pencil graphite electrode

Abstract

Abstract Hemoglobin nanoparticles (HbNPs) were prepared, characterized and immobilized covalently onto pencil graphite (PG) electrode to fabricate an improved amperometric H2O2 biosensor (HbNPs/PGE). HbNPs/PGE worked in optimum conditions of pH 6.5, temperature 30 °C, at an applied potential of −0.2 V. The biosensor exhibited wide linear response in a concentration range of H2O2 (0.001–1400 μM) with detection limit 1 nM. The biosensor revealed high sensitivity (4.21 ± 0.01 mA cm−2 μM−1), low response time (2 s) and a good agreement with standard enzymic colorimetric method with correlation coefficient (R2 = 0.99). The evaluation study of biosensor offered a good analytical recovery of 99.15%, when H2O2 concentration was added in the sera sample. In addition, within and between batches study of working electrode showed coefficients of variation as 0.044% and 0.030%, respectively. The application of biosensor was performed in sera of apparently healthy subject and patients affected with diabetes. There was a 10% loss in initial activity of biosensor after its regular use over a time period of 180 days, while being stored at 4 °C.