RUI-Collaborative Research-Electrokinetic Transport and Electric Field Control of Ion Motion through the Interior of Single-Walled Carbon Nanotubes

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Dr. Mark Ellison of the Department of Chemistry, Ursinus College and Dr. Michael S. Strano of the Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) are supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to study the motion of ions and molecules through the interior of carbon nanotubes. Flow of material at these dimensions is quite different from our everyday experience, so this research is expected to improve our understanding of how these ions and molecules are transported through tubes that are not much bigger in diameter than the objects themselves. The work is initially focused on the transport of amino acids and neurotransmitters, including acetylcholine and dopamine through the nanotubes. At a later stage, the nanotubes are outfitted with tiny gold electrodes to control the rate of flow through the tubes using an electric signal. If successful, the project is likely to impact the development of biosensing, medical testing, and electronic nanodevices. It is also likely to improve our understanding of the motion of biologically important molecules in biological channels and synthetic nanopores such as in the human brain. During the course of conducting this research, a diverse group of undergraduate students as well as female high school students are afforded a research experience at Ursinus College. In addition, the students benefit from visits to MIT to prepare nanotube devices and conduct experiments with the help of MIT graduate students. The project investigates the fundamental processes of the transport of small ions and molecules through single wall nanotubes (SWNTs). Chemical vapor deposition (CVD) is used to deposit SWNTs on silicon wafers and the devices are equipped with electrodes to conduct the needed ion current measurements. This, combined with SEM and Raman spectroscopy measurements, provides the necessary data to characterize the devices and to provide information on the mechanisms involved in the transport of ionic and molecular species through the nanotubes. The Ursinus undergraduate students travel to MIT to use equipment and instruments such as a chemical vapor deposition oven, scanning electron microscope, and a Raman microscope to construct the SWNT devices. The devices are brought back to Ursinus to conduct the voltage clamp measurements of ion transport. The work is initially focused on the transport of amino acids and neurotransmitters, including acetylcholine and dopamine, through the nanotubes. At a later stage, the nanotubes are outfitted with gold electrodes to gate and control the rate of flow through the tubes by an electric signal. The experiments are designed to provide the data needed to improve our understanding of ion and molecule transport through SWCNT nanopores and to explore the use of SWCNTs as conduits for the delivery of amino acids and neurotransmitters to specific targets. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.