Direct electrochemistry and electrocatalysis of myoglobin-based nanocomposite membrane electrode

The direct electron transfer of myoglobin (Mb) was achieved based on the immobilization of Mb/Silver nanoparticles (AgNPs) on glassy carbon electrode by multi-wall carbon nanotubes (MWNTs)-chitosan(Chit) film. The immobilized Mb displayed a pair of well-defined and reversible redox peaks with a formal potential (Eθ′) of − 24 mV (vs. Ag/AgCl) in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants (ks) of Mb confined to Chit-MWNTs film was evaluated as 5.47 s− 1 according to Laviron's equation. The surface concentration (Γ⁎) of the electroactive Mb in the Chit-MWNTs film was estimated to be (4.16 ± 0.35) × 10− 9 mol cm− 2. Meanwhile, the catalytic ability of Mb toward the reduction of H2O2 was studied. Its apparent Michaelis–Menten constant for H2O2 was 0.024 mM, showing a good affinity. The linear range for H2O2 determination was from 2.5 × 10− 5 M to 2.0 × 10− 4 M with a detection limit of 1.02 × 10− 6 M (S/N = 3). Moreover, the biosensor displays rapid response to H2O2 and good stability and reproducibility.

Research highlights
► Chit-MWNTs/Mb/AgNPs nanocomposite membrane electrode was prepared.
► Well direct electron transfer of myoglobin on the membrane electrode was achieved.
► The film electrode has good electocatalytic effect toward the reduction of H2O2.
► Amperomatric response of H2O2 has good linear relationship with its concentration.
► The rapid response, reproducibility and long time stability are advantages of the biosensor.