Magnetic Fe3O4 carbon aerogel and ionic liquid composite films as an electrochemical interface for accelerated electrochemistry of glucose oxidase and myoglobin

Synthesized magnetic ferroferric oxide carbon aerogel (Fe3O4-CA) was characterized by scanning electron microscope (SEM), atomic force microscopy (AFM) and N2 adsorption–desorption isotherm measurements. Subsequently, the Fe3O4-CA was mixed with ionic liquid (IL) to form a stable composite film, which was characterized by atomic force microscopy (AFM) and used as an electrochemical interface for accelerating electrochemistry of glucose oxidase (GOx) and myoglobin (Mb). The results demonstrated that direct electron transfer of GOx and Mb, respectively, was realized on the surface of Fe3O4-CA/IL with a pair of well-defined quasi-reversible redox peaks. The heterogeneous electron transfer rate constant (ks) and the surface coverage (Γ*) were calculated as 1.30 s−1 and 4.10 × 10−10 M cm−2 for Fe3O4-CA/IL/GOx-CPE, 0.92 s−1 and 2.02 × 10−9 M cm−2 for Fe3O4-CA/IL/Mb-CPE, respectively. Moreover, the immobilized Mb exhibited excellent bioelectrocatalytic activity toward the reduction of hydrogen peroxide (H2O2). The biosensor displayed broad linear response to H2O2 in the range from 10 μM to 1450 μM with a detection limit of 3.2 μM. The results demonstrated that Fe3O4-CA/IL composite films could be a potential biocompatible interface owing to their excellent electron transfer activities, abundant mesoporous structures and large specific surface area, and wide potential applications may be developed in biosensors and biocatalysis.