The Research On Electron Transfer Process Of Biological Molecule Of Porphyrin At The Liquid/Liquid Interface

A liquid/liquid (L/L) interface has been suggested as a simple model for biological membranes and the charge(electron and ion) transfer across it has been studied as an essential physicalchemical process. Many important chemical and biological systems(such as chemical sensors, drug release of pharmacology, phase transfer catalysis) and simulation of biomembrane could be investigated at the L/L interface, which was significant for advancing the dynamic theories to interface process and understanding many important physiological processes, e.g. energy metabolizing, free-radicel presenting and disappearing.Thin-Layer Cyclic Voltammetry (TLCV) was developed by Anson et. al in 1998, which has been used to study charge transfer at L/L interface, and the advantages of TLCV include its simplicity and convenience. As a new technology of scanning probe microscope, scanning electrochemical microscopy (SECM) was developed by Bard and co-workers in 1989. SECM can be used in a variety of ways, e.g., as an electrochemical tool to study heterogeneous and homogeneous reactions, as an imaging device(microscope) to acquire graphics of the substrates and distinguish the differences of the surface, and it can be used for fabricate some microstructures and study many biosystems.There are three parts in this paper, main contents are as follows:1. A short review was given on electrochemistry of L/L interface. The historical background and the basic principles outlined of TLCV and SECM was briefly summarized. Especially, the applications of the two technologies in interfacial electrochemistry were discussed in detail. These applications included: (1) SECM was used to provide a means of characterizing thin films, modified electrodes and conductive polymers in terms of structure and mechanism; (2) The catalytic activity of immobilised redox enzymes were studied by SECM; (3) Employed TLCV and SECM to study charge transfer (iron transfer (IT) and electron transfer(ET)); (4)Single molecular electrochemical reactions could be detected with the SECM and nanometre-scale tips; (5) SECM were provided as a tool to investigate cellular activities at the single cell level.2. Combined with SECM, the processes of ET in following two systems at NB/W interface were investigated by TLCV: (1) ascorbic acid (H₂A, in water)-ferrocene(Fc, in NB) system; (2)dopamine(DA, in water)-ferrocene (Fc, in NB) system. The results from the two different approaches showed a reasonable agreement, which not only demonstrated the simplicity and the convenience but also expanded the research region of TLCV.3. The processes of ET between zincoporphyrins with different radicels (tetraphenylporphyrin zinc (ZnPor), menohydroxyl porphyrin zinc(ZnPor(OH), methyloxy porphyrin zinc ZnPor(OCH₃) in NB phase) which were synthesized in our lab and ferrous ferricyanide(in aqueous phase) were investigated by SECM with feedback model and the formal rate constants of heterogeneous ET were calculated. Taking ClO4- as common ion, the process of it's cortrolling the potential drop at the L/L interface and the effects of various radicels of metoporphyrins on ET have been discussed.With the development of chemistry, it has been intercrossed with physics, information technology, life sciences and medicine etc, which make the study of interface electrochemistry more significant. Therefore, appearing of some new methods and technologies on studying interface electrochemistry will be more available to understand the complex systems in nature.