Peroxidase model electrodes: Self-mediation of heme peptide multilayer-modified electrodes and its application to biosensing with adjustable dynamic range

Bioelectrochemistry of Heme Peptide at Seamless Three-Dimensional Carbon Nanotubes/Graphene Hybrid Films for Highly Sensitive Electrochemical Biosensing

“…12,13 As shown in Figure 5A, the steady-state cathodic current densities for H 2 O 2 reduction at the HP/CNTs/G electrode were clearly much larger than those at the bare CNTs/G electrodes. In addition, the cathodic currents at the HP/CNTs/G electrode were larger than those at the HP/G electrode.…”

“…This is because the rate-determining step for the HP-ML/G electrode is the diffusion of H 2 O 2 (≤3.0 × 10 −5 M) or proton and/or e − of the electron self-exchange (≥3.0 × 10 −5 M), as previously reported. 13 In fact, the catalytic current for H 2 O 2 reduction at the HP-ML/G electrode significantly increased when the electrolyte solution was stirred. The HP molecules at only the interface of the HP-ML/G electrode might partially contribute to the H 2 O 2 reduction, because of their dense and tight immobilization on the flat surface of graphene.…”

“…If the CNTs/G film and graphene are excessively immobilized with the same amounts of HP molecules and diffusion of H 2 O 2 and/or H + is not influenced by the microvoid in the CNTs/G film, the cathodic current should show roughly the same values, because of the self-mediation among HP molecules. 13 In order to demonstrate the issue, we used the HP-ML/CNTs/G and HP-ML/G electrodes, the Γ values of which were determined to be ∼5.5 × 10 −10 mol cm −2 from the integration of CV peaks (charge) at the scan rate of 10 mV s −1 (see Figure S2 in the Supporting Information). As shown in Figure 4, the cathodic currents at the HP-ML/CNTs/G and HP-ML/G electrodes were larger than those at the HP/CNTs/G and HP/G electrodes, respectively, because of the increase in the Γ value.…”

Peroxidase-modified cup-stacked carbon nanofiber networks for electrochemical biosensing with adjustable dynamic range

“…When eqn 1 is the ratedetermining step in eqn 1-3, eqn 6 can be rewritten as follows. 36,42 R = 100/(1/K app C i + 1)…”

Electrochemical properties of seamless three-dimensional carbon nanotubes-grown graphene modified with horseradish peroxidase

“…Toward the development of highly sensitive enzyme-based electrochemical biosensors without the above problems, we previously constructed CNTs/G hybrid electrodes modified with GOx [15] or heme peptide (HP) [16], which has a similar structure to the active center of peroxidase and has often been used for H 2 O 2 sensing [17][18][19]. However, the catalytic activity of HP is lower than that of HRP and therefore HRP-based biosensor would be more sensitive compared to one based on HP.…”