Direct Electron Transfer of Hemoglobin Immobilized in Multiwalled Carbon Nanotubes Enhanced Grafted Collagen Matrix for Electrocatalytic Detection of Hydrogen Peroxide

Abstract

AbstractThe direct electron transfer and electrocatalytical behavior of hemoglobin (Hb) immobilized in multiwalled carbon nanotubes enhanced grafted collagen matrix (grafted collagen‐MWNTs) was studied. The immobilized Hb displayed a pair of redox peaks with a formal potential of −(0.360±0.002) V (vs. SCE) and a surface‐controlled electrode process. The electron transfer rate constant and surface coverage of Hb was (6.3±0.2) s−1 and (5.0±0.3)×10−10 mol/cm2, respectively. Based on the direct electrochemistry, a novel biosensor for H2O2 ranging from 0.6 to 30 μM with a linear regression equation of I (μA)=0.026 C+0.029 (R= 0.9999, n= 29) was constructed. Owing to the good biocompatibility and high enzyme loading of the matrix, the biosensor exhibited a low limit of detection of 0.13 μM at 3 σ, a time of less than 5 s to achieve 95% of the maximum steady‐state response, a sensitivity of 103 mA/M cm2 and acceptable reproducibility with a RSD of 2.5%. It could retain 95% of its initial response to H2O2 after a month. Grafted collagen‐MWNTs provided a good matrix for protein immobilization and biosensors preparation.