Direct Electrochemistry And Electrocatalysis Of Redox Proteins In Multicomposite Materials

Studies on the direct electrochemistry and electrocatalysis of redox proteins canbe used for the understanding of the mechanisms of electron transfer reactions andoxidation/reduction in life process, which can also be proposed as a sensitive methodfor determination. Ionic liquids （ILs） have been utilized in the fields ofelectrochemistry and electroanalysis due to their higher ionic conductivity, widerelectrochemical windows, non-volatile and non-toxic. The special characteristics ofnanomaterials such as high surface area and high activity, also make them the mostpromising candidates used in electrochemical sensor. The main points of the thesis areas follows:1. Co₃O₄nanoflower and Cu₃Mo₂O₉nanosheet were synthesized by hydrothermalmethod and applied to hemoglobin and myoglobin electrochemistry. Ionic liquids （ILs）modified carbon paste electrode （CPE） were constructed based on the substitute ofparaffin with1-butyl-3-methyltetrafluoroborate （BMIMBF4） to mix with graphitepowder. Protein was immobilized on the surface of CILE with chitosan （CTS） andCo₃O₄nanoflower, GR, Nafion,[EMIM]Br and Cu₃Mo₂O₉nanosheet compositematerial. The characteristics of Hb and Mb in these modified films were investigatedby scan electron microscopy, FT-IR spectrum, UV-Vis spectrum and electrochemicalmethods. The results showed that Hb and Mb retained its native structure in thesecomposites. A pair of quasi-reversible, stable and well-defined cyclic voltammetricpeaks appeared, and the synergistic effects between IL and multicomposite can greatlypromote the electron transfer rate. The electrochemical behaviors of Hb and Mb in themodified electrode were carefully investigated with the electrochemical parameterscalculated. The Mb and Hb modified electrode showed excellent electrocatalyticbehaviors to the reduction of trichloroacetic acid （TCA）.2. The composites of graphene （GR） nanosheets decorated by platinum （Pt）nanoclusters were prepared via simultaneously reduction of graphite oxide and H₂PtCl₆which was further modified on the CILE surface with Nafion and myoglobin （Mb） wasimmobilized on the electrode. The electrochemical behaviors of Mb on the modified electrode were carefully investigated with the electrochemical parameters calculated.UV-vis and FTIR results showed that Mb in these films retained its native structure.Electrochemical behavior of the Nafion/Mb-GR-Pt/CILE was investigated with a pairof well-defined redox peak appeared in pH7.0PBS buffer. The modified electrodesshowed excellent electrocatalytic behaviors and low detection limit to the reduction oftrichloroacetic acid （TCA） with the apparent Michaelis-Menten constants （KMapp）calculated.3. Ionic liquids （ILs） modified carbon paste electrode （CPE） were constructedbased on the substitute of paraffin with1-Butylpyridinium hexafluorophosphate（BPPF₆） to mix with graphite powder. Hemoglobin （Hb） was immobilized on thesurface of CILE with Nafion-graphene （GR）-CdTe composite material with themodified electrode denoted as Nafion/CdTe-GR/CILE. The electrochemical behaviorsof Hb were carefully investigated with the electrochemical parameters calculated. Thecharacteristics of these modified electrodes were investigated by UV-Vis spectrum,FT-IR spectrum, transmission electron spectrum （TEM）, scan electron microscopy（SEM）, and electrochemical methods. The fabricated Nafion/Hb-CdTe-GR/CILEshowed good electrocatalytic ability to the reduction of trichloroacetic acid （TCA） witha linear range from1.4to15.0mmol/L, and the detection limit （3σ） as0.53mmol/L.