Sensors: Near Infrared Fluorescent Single Walled Carbon Nanotubes as Solution Phase Optical Sensing Materials

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The goal of this project is to develop a new class of sensing materials for solution phase detection of molecules based on the near-infrared fluorescence of single walled carbon nanotubes. Carbon nanotubes are a part of a select class of electronic materials that fluoresce in the infrared region. Scattering and auto-fluorescence in a wide range of biologically relevant media prohibit accurate fluorescent detection in the visible spectrum. Single walled carbon nanotubes are ideal sensing materials, having diameters near 1 nm and lengths spanning several microns. Their geometry is unique among molecular probes. They conduct electrons under near ballistic conditions or over large distances with minimal scattering. This provides the basis for powerful sensing technologies because large areas of the nanotube surface are sensitive to single molecule adsorption events. Adsorbates on the surface of a nanotube can localize valence electrons or conversely donate electron density to the conduction band and either event is registered as a change in the nanotube optical emission properties. This project will address three technological hurdles towards this goal: (i) understanding the molecule-nanotube surface interactions and their effect on optical properties, particularly polarity induced solvatochromic shifts and charge transfer interactions; (ii) designing adsorbed interfaces to introduce specificity at the nanotube surface towards desired molecules; and (iii) engineering working sensor devices for molecular detection in unconventional media such as highly turbid solutions or biological relevant media. The project will also develop new coursework material and will participate in program that improves participation of students from under-represented groups. Activities in the engagement of the public in topics of science and technology are also planned.