Study On The Electrochemical Behaviors Of Cytochrome C At Electrode Modified With SAM And Ionic Liquids

Most chemical reactions during the metabolism are catalyzed by active protein-enzymes,and the basal movement in human body is charge movement during which Cytochrome c (Cyt.c) palys an very important role. Redox of Cyt.c in human body is reversible but irreversible on the metal electrodes such as Hg,Pt,Au,Ag and its direct electron transfer can only be completed with the help of promoter or mediator.A gold electrode modified with 2-aminoethanethiol(2AT)self-assembled monolayer (SAM) has been fabricated. The characteristics of 2AT SAM have been investigated by cyclic votammetry(CV),quartz crystal microbalance(QCM),Raman spectroscopy,electrochemical impedance spectra(EIS). Results showed that 2AT SAM was an effective promoter for Cyt.c electron transfer.The 2AT assembles process and its possible promotion mechanism were discussed with the electrochemical quartz crystal microbalance (EQCM) and EIS measurements.Cyt.c was assembled onto the Au electrode by using layer upon layer technic to form Cyt.c/2AT/Au modified electrode,the Cyt.c/2AT/Au electrode also showed a pair of redox peaks apparently in PBS solution but was not so good when compared to 2AT/Au electrode in Cyt.c solution.At the scan rate of 20mV/s reversible singals of Cyt.c on the 2AT/Au electrode was observed.It's redox peak potential was 48mV and -7mV respectively. So the formal potential is 20.5mV. When in PBS solution, a pair of redox peaks was also found on the Cyt.c/2AT/Au electrode, but its's not as well as 2AT/Au electrode in Cyt.c solution.Room-temperature ionic liquids are compounds that only consist of ions and are liquids at or above room temperature.They have many advantages such as low melting point,lack of vapor pressure,broad electrochemical window,favorable solvent miscibility,thermal stability and high viscidity tolerance and density.It becomes a green solvent and is used widely in electrochemistry,organic synthesize,separate analyzing fields.Biologic molecules remain their activities in ionic liquids and it is a good medium for biologic molecules during their electrochemical behaviors.We synthesized five ionic liquids according to references and the productions were proved by 1H-NMR.Ionic liquids was dropped onto the GC electrode to form modified electrode.And the electrochemical behaviors of cytochrome c at the modified GC electrode were studied by CV,also EIS was used synchronously to detect the chemical reaction. According to the equivalent circuit experimental results was simulated by which we studied the electron transfer mechanism. The results showed that both of the imidazole ionic liquid were good promoters for the direct electron transfer(DET) of Cyt.c which means that it affects little to the DET of Cyt.c when changing the anion of the ionic liquids;but no obvious electrochemical singals was found on the quaternary ammonium ionic liquid modified electrode which gave the information that quaternary ammonium cation was not a good promoter for DET of Cyt.c.A pair of good electrochemical redox peaks were also found on the pyridine hexafluorophosphate ionic liquid modified GC electrode which told that pyridine cation was also a good DET promoter for Cyt.c.