Direct Electrochemistry And Electrocatalysis Of Protein In Nanoparticle-Ionic Liquid Composite Film Modified Electrode

Nanomaterials have many specific physical, electronic and chemical characteristics such as high surface area, good biocompatibility and strong adsorption ablity, which have been widely used in the field of electrochemistry. Ionic liquids (ILs) have many unique physicochemical characteristics such as good chemical and thermal stability, relatively high ionic conductivity, negligible vapor pressure, wide electrochemical windows and good biocompatibility, which had been used in the area of electrochemistry and electroanalysis.In this paper novel nanobiocomposite materials were fabricated by mixing nanomaterial with ionic liquid and Nafion together, which was used to immobilize the protein on the surface of carbon electrode. The electrochemical behavior of the protein and its electrocatalytic properties were studied.The main contents of this paper are as follows:(1) A novel nanobiocomposite was prepared by mixing ZrO₂ nannoparticle with ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ( [EMIM]BF₄ ) and Nafion together, which was further used to immobilize myoglobin ( Mb ) on the surface of carbon ionic liquid electrode ( CILE ). Spectroscopic results indicated that Mb remained its native structure in the nanobiocomposite material. Cyclic voltammetric results showed a pair of well-defined redox peaks appeared in pH 7.0 phosphate buffer solution ( PBS ), indicating the direct electron transfer of Mb was realized on the modified elecctrode. Mb exhibited a surface-controlled electrochemical process and the electrochemical parameters such as electron transfer coefficient (α) and electron transfer rate constant ( k_s ) were calculated as 0.499 and 0.813 s^-1, respectively.This electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid ( TCA ). (2) A nanobiocompatible was prepared by mixing ZnO nannoparticle ( nano-ZnO ) with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ( BMIMPF6 ) and Nafion together, which was further used to immobilize hemoglobin ( Hb ) on the surface of carbon ionic liquid electrode ( CILE ). A pair of quasi-reversible redox peaks appeared in pH 7.0 phosphate buffer solution, which was attributed to the electrode reaction of Hb Fe (Ⅲ) / Fe (Ⅱ) redox couple. The presences of nano-ZnO and BMIMPF6 in the film can retain the bioactivity of Hb and greatly enhance the direct electron transfer of Hb. The immobilized Hb showed high stability and good electrocatalytic ability to the reduction of hydrogen peroxide and O₂.(3) A novel nanobiocomposite was prepared by mixing Mg₂-Al-LDH with ionic liquid 1-acetoxy-3-methylimidazolium tetrafluoroborate ( CMMIMBF₄ ) and Nafion together, which was further used to immobilize myoglobin ( Mb ) on the surface of carbon ionic liquid electrode ( CILE ). The electrochemistry and electrocatalysis of Mb in the composite film were carefully studied.