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RESEARCH
Our research interests are in the emerging field of nanoelectrochemistry. We employ nanometer-sized electrochemical probes for molecular level characterization of chemical processes and materials. A wide variety of phenomena are studied including charge-transfer reactions at the solid/liquid and liquid/liquid interfaces, mechanisms of stress corrosion, bioelectrochemistry, and biomedical imaging. The main focus is on obtaining quantitative physico-chemical information by combination of experiments with mathematical modeling and computer simulations.
Scanning electrochemical microscopy (SECM) is used as a tool for these studies. This method combines the capabilities of microelectrode electrochemistry with those of scanning probe microscopies, such as STM. It can provide spatially resolved information about local chemical properties of various surfaces. An SECM probe is a small (nm-sized) electrode, which can penetrate thin films and biological membranes and be used to extract information about potentials, kinetics, and chemical composition. We employ SECM to probe the dynamics of electron and ion transfers at the interface between two immiscible electrolyte solutions and inside immobilized biological cells.
We also maintain an active interest in development of electrochemical techniques for analytical applications. These include ion-selective electrodes and pipette-based amperometric sensors. Examples of ongoing research projects in our group: (i) Study of redox reactivity and charge transfer processes in living cells by SECM. This is a joint project between myself and a biochemistry professor, Susan Rotenberg. We are trying to discriminate between normal and cancerous cells using the differences in their redox reactivities and exploring the possibility of electrochemical diagnostic of cancer. Most recent developments include nanoscale electrochemical imaging of cell surfaces and SECM experiments inside living cells. (ii) Development of and experiments with nm-sized metal electrodes. They are being used to measure kinetics of electron transfer reactions at the metal/solution interface and for high-resolution chemical imaging. A recently produced electrochemical nano-junction allows the studies of electron transfer reactions, adsorption, and electrical double layer at a single molecule level. (iii) Probing charge transfer processes and chemical reactions at nanoscopic liquid/liquid interfaces. Nanometer-sized pipettes and SECM are used to explore the relations between the kinetics of ionic reactions and interfacial structure. Currently, we are working on validation of the new mechanism for an important class of ion-transfer reactions. (iv) Electrochemical attosyringe. A novel device was invented to dispense attoliter (10-18 L) volumes of liquids. Potential applications include injection of DNA and proteins into living cells and preparation of sensor and catalyst microarrays. This device can also be used as a nano-pump. (v) Electrochemistry at the water/ionic liquid
interface. This is our joint project with Prof. Takashi Kakiuchi ( |