Studies On The Hemoglobin Biomimic Membranes And Their Applications In Electrochemical Sensing

Hemoglobin (Hb) is a respiratory protein in red blood cells of vertebrates, composed by the globin and heme, and it is the carrier of oxygen in the blood. Based on the study of electrochemistry of hemoglobin, we can not only explore the mechanism of electron transfer and the relationship between the structure and function in biological macromolecules, but also understand the material metabolism and energy exchange process in life system. Thus, biosensor with high catalytic performance can be fabricated.In this paper, in order to achieve the direct electron transfer of hemoglobin, server kinds of material with good biocompatibility, such as carbon nano materials, polymer materials were used to immobilize hemoglobin with appropriate methods. Base on the special interaction between hemoglobin and these biomimic materials, the direct electron transfer of hemoglobin was achieved. These materials not only provide a suitable miro-environment for hemoglobin, but also significantly increase the electron transfer rate between hemoglobin and electrode. The chemically modified electrode could catalyze the reduction of hydrogen peroxide (H₂O₂), nitric oxide (NO) and other small molecules. The main work was summarized as follows:(1) A film composed by acetylene black and ionic liquid 1-butyl-3-methylimida- zolium hexafluoro-phosphate (BMIMPF₆) was firstly used for immobilizing hemoglobin and a new electrochemical biosensing platform was developed. The resulting biosening film was demonstrated by ultraviolet–visible (UV–vis) spectra and electrochemical impedance spectroscopy (EIS). The results showed that hemoglobin in acetylene black and ionic liquid composite film still maintain its biological activity,while promoting the electron transfer between the hemoglobin and the electrode. The modified electrode can catalytic the reduction of H₂O₂, NO.(2) The direct electrochemistry of hemoglobin was achieved by using a new type of synthetic polymer material - quaternized celluloses. Stable layer-by-layer biomimic films were grown on the electrode surface by alternate adsorption of layers of polyanionic quaternized cellulosed and positively charged hemoglobin from their aqueous solutions. The results show that the immobilized hemoglobin not only remained its native structure but also can catalyze the reduction of H₂O₂. Based on this, a new type of non-mediator hydrogen peroxide sensor was constructed. (3) Hemoglobin was successfully immobilized on the electrode surface with combined the excellent performance of methylene blue and nano carbon microspheres. Hemoglobin in the composite film showed good direct electrochemistry. The results of UV-Vis spectra, atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) demonstrated that electrostatic interaction existed between hemoglobin and the composite, which changes the orientation of hemoglobin and is conducive to the electron transfer. The results showed that the immobilized hemoglobin maintain its good biological activity and can catalyze the reduction of H₂O₂.(4) A modified electrode was constructed byβ-cyclodextrin and ioniclic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄). The hemoglobin was successfully immogbilized in the film with its excellent biocompatibility. UV-Vis spectra showed that the immobilized hemoglobin in the composite film was still able to maintain its native conformation and biological activity. Based on this modified electrode, the reduction of H₂O₂ can be catalyzed with rapid response and excellent stability.