Sunday, May 7, 2006 | Denver, Colorado
Plaza Ballroom F, Concourse Level
This lecture will focus on biofunctionalized nanotubes and a new paradigm in electroanalytical chemistry based on these tubes. This work takes its inspiration from Mother Nature – the ultimate nanotechnologists and electrochemist.
Embedded in the cell membrane of every living cell are protein nanotubes called ion channels. These channels control what ions get into and out of the cell, they maintain a potential difference across the cell membrane, and they are involved in signaling between cells and nerve impulse propagation. One class of such channels – ligand-gated ion channels (LGICs) - does exquisitely selective and sensitive bioanalytical chemistry. LGICs are closed in the resting state but open when a specific ligand is detected by highly selective molecular-recognition sites on the channel. When open, an ionic current flows through the channel and across the cell membrane. Hence LGICs combines the two key elements of a biosensor – molecular-recognition followed by transduction of this recognition event into a measurable (ion-current) signal. As an electrochemist, this is a very interesting concept because via this recognition/transduction strategy, the channel detects a non-redox-active species, the ligand, electrochemically.
Our biofunctionalized nanotubes mimic this function. The nanotubes are prepared by the template-synthesis method, and the sensing device typically consists of a single conically shaped gold nanotube embedded in a synthetic polymer membrane. Gold is a propitious choice of nanotube material because it can be easily functionalized using thiol chemistry. We functionalize the inner surfaces of the nanotubes with small molecules, proteins, DNA, and other biomolecules. As in the LGIC these surface-bound biomolecules act as molecular-recognition agents for binding analyte molecules to the tube walls. In further analogy to LGIC, we pass an ion current through the biofunctionalized nanotube, and binding of the analyte to the molecular-recognition agent modulates the value of this ion current. Sensors of this general type that detect protein, DNA, and small-molecule analytes will be discussed.
Charles R. Martin obtained his BS degree from Centre College of Kentucky in 1975 and was elected to Phi Beta Kappa. He did his graduate work at the University of Arizona, obtaining a PhD in electroanalytical chemistry in 1980 under the direction of Prof. Henry Freiser. He then moved to the University of Texas at Austin where he was a Robert Welch Postdoctoral Fellow with Prof. Allen J. Bard. His research interests are in the areas of nanoscience and bioanalytical chemistry. Beginning in the 1980s, his research group pioneered a powerful and versatile approach for preparing nanomaterials called the template method. His research currently focuses on applications of template-prepared nanotubes and nanotube membranes to biosensors and bioseparations – the bio/nano interface. Professor Martin was the 1999 recipient of the Carl Wagner Memorial Award of The Electrochemical Society and is a Fellow of the Society.