Direct Electrochemistry And Electrocatalysis Of Hemoglobin Using Ionic Liquid BMIMPF₆ As Modified Material

Hemoglobin (Hb) is one kind of heme protein, which can be used as the storage and carrier of oxygen. Studies on the direct electrochemical behaviors of Hb can be used for the understanding of the mechanisms of electron transfer reactions. Recently, room temperature ionic liquids (RTILs) have been used in electrochemistry of protein and enzyme because many biomolecules have excellent properties in RTILs. RTILs can be used either as supporting electrolyte or modifier for electrode in the field of electroanalysis. Since electroanalysis has inherent advantages such as lower detection limit and wider dynamic range, it can be used to investigate the electrochemical behaviors of biomolecules. In this thesis the direct electrochemical investigation of Hb was connected with electroanalytical method and the thesis can be summarized as follows:1. The direct electrochemistry of Hb was carefully studied on the carbon ionic liquid electrode (CILE). Room temperature ionic liquids (RTILs) modified carbon paste electrode (CPE) was constructed based on the substitute of paraffin with 1-butyl-3-methylimidazolium hexafluorophate (BMIMPF₆) to mix with graphite powder. Hb was immobilized on the surface of CILE with sodium alginate film, sodium alginate and nano-SiO₂ film or Nafion and nano-CdS film by step-by-step method. The characteristics of Hb in these modified films were investigated by scan electron microscopy, UV-Vis, FT-IR and electrochemical methods. The results showed that Hb in these films retained its native structure. A pair of well-defined and quasi-reversible cyclic voltammetric peaks was appeared. The electrochemical behaviours of Hb in the modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode showed excellent electrocatalytic behaviors to the reduction of hydrogen peroxide (H₂O₂), trichloroacetic acid (TCA), sodium nitrite (NaNO₂) and oxygen (O₂).2. The direct electrochemistry of Hb in the mixture with BMIMPF₆ was carefully studied on the carbon paste electrode (CPE). Hb was immobilized on the surface of CPE with BMIMPF₆-nano-CuS film and SA-nano-SiO₂-BMIMPF₆ film by grounding the mixture in an agate mortar. The direct electrochemistry and electrocatalytic of Hb in these modified films were investigated. The results showed that Hb in these films retained its native structure and bioactivity. A pair of well-defined and quasi-reversible cyclic voltammetric peaks was appeared and the electrochemical parameters were furthur calculated. The Hb modified electrode also showed excellent electrocatalytic behaviors to the reduction of hydrogen peroxide (H₂O₂), trichloroacetic acid (TCA), sodium nitrite (NaNO₂) and oxygen (O₂). The apparent Michaelis-Menten constants (K_M^app) of the sensors were calculated.