Fabrication and Electrochemical Behaviors of Several Hemoglobin Modified Electrodes
|School||Qingdao University of Science and Technology|
|Keywords||room temperature ionic liquids hemoglobin carbon nanotubes electrocatalysis direct elelctrochemistry trichloroacetic acid H2O2|
Hemoglobin （Hb） is one kind of heme protein, which can be used as model molecule for the investigation the direct electron transfer of redox proteins. Due to the difficulty of direct electron transfer of redox proteins with the bare working electrode, different kinds of film modified electrodes were devised to accelerate the electron transfer rate. In recent years, nanomaterials had been widely used in fabricating the protein film modified electrodes for their unusual physical and chemical properties. Room temperature ionic liquids （RTILs） have attracted the interests of electrochemist for their specific properties, such as relatively high ionic conductivity, good chemical and thermal stability, wide electrochemical windows and good biocompatibility. In this thesis, we prepared several Hb modified electrodes based on room temperature ionic liquids （RTILs） and unique properties of nanoparticles to investigate the electrochemistry and electrocatalysis of Hb. The thesis can be summarized as follows:1. The carbon ionic liquid electrode （CILE） was prepared for investigation the direct electrochemistry of Hb. The CILE was constructed by mixing graphite powder and 1-butyl-3-methylimidazolium hexafluorophate （BMIMPF6） thoroughly. Hb was immobilized on the surface of CILE with Nafion and nano-ZnO film or chitosan and multi-walled carbon nanotubes （MWCNT） film by step-by-step method. In these modified films, the characteristics of Hb were investigated by scan electron microscopy （SEM）, UV-Vis spectrum, FT-IR and electrochemical methods. The results showed that Hb retained its native structure in these films. A pair of well-defined quasi-reversible redox peak of heme Fe（III）/Fe（II） couple appeared. The electrochemical parameters of Hb in the composite film were further carefully calculated. The Hb modified electrode showed excellent electrocatalytic behaviors to the reduction of trichloroacetic acid （TCA）.2. The direct electrochemistry of Hb in the 1-Ethyl-3-methylimidazolium tetrafluoroborate （EMIMBF4） or MWCNT modified CPE was carefully studied. By mixing Hb with graphite powder, MWCNT and paraffin or EMIMBF4 together with a Nafion film applied on the electrode surface as the protective and immobilization layer, Nafion/Hb-IL-CPE and Nafion/Hb-MWCNT-CPE were prepared and further studied by electrochemical method and scanning electron microscopy （SEM）. Direct electrochemistry of Hb in the carbon paste bioelectrode was successfully achieved. In pH 7.0 phosphate buffer solution （PBS）, a pair of quasi-reversible redox peaks was appeared and the electrochemical parameters were furthur calculated. The Hb modified electrode also showed good electrocatalytic ability to the reduction of TCA and hydrogen peroxide （H2O2）.