Applications of Novel Scanning Probe Methods to Electrochemical Studies.

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The Analytical and Surface Chemistry program supports this project by Professor Allen Bard of the University of Texas at Austin in which several new scanning probe/electrochemical microscopy techniques will be developed. First, scanning electrochemical microscopy (SECM) will be applied to the measurement of ion flux through a single channel of a bilayer lipid membrane, and then of living cells. Preliminary experiments have detected iodine transport across a membrane, and other researchers have used Prof. Bard's SECM method to monitor molecular ion transport through living cell membranes. There is the potential to use SECM both as an imaging device and as a quantitative tool to extract kinetic information about ion transport. A potential area of application is in the neuronal microenvironment and the release of neurotransmitters during exocytosis. A second instrument combines the SECM with electrogenerated chemiluminescence. Previous studies demonstrated the potential, but were limited by tip size and tip-substrate spacing. Newly developed probes will overcome these problems and permit detailed studies of electrochemical reactions at and near electrode surfaces. Applications include characterization of molecular electronic devices via a method termed "molecular voltammetry". In molecular scale nanostructures, the discreteness of the electronic charge has been demonstrated to play a prominent role in device performance, and these can be further studied with the proposed analytical methods.Scanning probe microscopy is widely used in the study of surfaces, including chemically reactive electrode surfaces to the surface of a living cell. In this project, new techniques will be developed with a goal toward improving the quantification of the imaged features. For example, ion channels have been imaged on cell membranes. The next question is: What is the rate of ion transport through the imaged ion channel?