Electrocatalytic Properties of Heme Proteins in Layer‐by‐Layer Films Assembled with SiO₂ Nanoparticles

Abstract

Abstract Electrochemical and electrocatalytic properties of heme proteins, including myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP), in layer‐by‐layer films assembled with SiO 2 nanoparticles were investigated at pyrolytic graphite (PG) electrodes. The stable layer‐by‐layer {SiO 2 /protein} n films showed a pair of well‐defined, nearly reversible cyclic voltammetric peaks at about −0.25 V (vs. SCE) at pH 5.5, characteristic of the protein heme Fe III /Fe II redox couples. The proteins in the films displayed good electrocatalytic activities toward various substrates such as oxygen, hydrogen peroxide, trichloroacetic acid, and nitrite, and showed a potential applicability in fabricating the new kind of biosensors without using mediators. Electrochemical parameters of the protein films such as apparent heterogeneous electron transfer rate constant ( k s ) and formal potential ( E °′) were estimated by square‐wave voltammetry and nonlinear regression analysis. The influencing factors like the number of bilayer and the pH of external solution were also investigated.