Application of Cobalt Oxide Nanoflower for Direct Electrochemistry and Electrocatalysis of Hemoglobin with Ionic Liquid as Enhancer

A composite bionanomaterial was prepared by combining Nafion, flowerlike cobalt oxide (CoO) nanoparticles, hemoglobin (Hb), and ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate. Then it was further applied on the surface of a carbon ionic liquid working electrode fabricated with 1-ethyl-3-methylimidazolium ethylsulfate as the modifier. Ultraviolet visible and Fourier transform infrared spectroscopic results indicated that Hb molecules in the composite film retained the native structure. Cyclic voltammetric results showed that a pair of well-defined redox peaks appeared in 0.1 mol L-1 pH 4.0 phosphate buffer solution, indicating that the direct electron transfer of Hb with the underlying electrode was realized. The results could be attributed to the synergistic effect of CoO nanoflower and IL in the composite film, which provided a specific microenvironment to keep the native structure of Hb and promoted the electron transfer rate of Hb. The electrochemical parameters of Hb on the modified electrode were carefully calculated. The composite material modified electrode showed excellent electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid and H2O2, which exhibited advantages such as high sensitivity, good stability, and wide dynamic range. Therefore, it has potential application in third-generation electrochemical biosensors.